JP2007196924A - Vehicle braking unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate difference of braking forces between front wheels and rear wheels in liquid pressure braking units of the front wheels and rear wheels at the beginning of braking in a hybrid vehicle. <P>SOLUTION: The liquid pressure braking unit 20 supplies operational liquid into wheel cylinders through the first passage in the vicinity of a source of liquid pressure and the second passage communicating to the first passage via a valve, and adds the liquid pressure braking force to the wheels 9. A hybrid ECU 7 determines a distribution ratio of the liquid pressure braking force and regenerative braking force, and requests the braking force to the liquid pressure braking unit 20 and a regenerative braking unit. When there is difference of responses of raising pressures of the operational liquid pressures between the first passage and second passage, a cooperative controller commands the regenerative braking unit to add the driving force or regenerative braking force coming from the motors for front wheels 6 and rear wheels 16 to the wheels 9 so as to supplement the shortage of the liquid pressure braking force at the beginning of braking due to delay of the response. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a braking technique in a hybrid vehicle including both a hydraulic brake unit and a regenerative brake unit.

2. Description of the Related Art Conventionally, an electronically controlled vehicle braking device is known that can control a braking force by adjusting a hydraulic pressure applied to each wheel cylinder by a pressurization source and a hydraulic pressure control unit. In such a vehicle braking device, the cost can be reduced by reducing the number of control valves for pressure increase or pressure reduction. Patent document 1 has a set of pressure-increasing linear control valves and pressure-decreasing linear control valves, and is separated into two passages that communicate with the wheel cylinders of the disc brakes installed on different wheels by the communication valves. A vehicle braking device having a hydraulic fluid passage is disclosed.
JP-A-11-180294 JP 2002-95108 A JP 2001-169405 A JP 2004312962 A JP-A-10-94107

  However, as in Patent Document 1, when the two passages are communicated with each other in the hydraulic fluid passage with the communication valve interposed therebetween, the communication valve acts as an orifice. In particular, in the initial stage of braking, the pressure increase response when pressure is increased on both sides of the communication valve. There may be differences in sex. This difference in pressurization response appears as a difference in hydraulic braking force between the wheels corresponding to the passages on both sides of the communication valve.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle including a hydraulic brake unit in which hydraulic fluid is supplied from one hydraulic pressure generation source to a plurality of passages communicating with separate wheels. The present invention provides a technique for compensating for a braking force difference between wheels caused by a hydraulic response difference between passages.

  One embodiment of the present invention is a vehicle braking device that brakes a vehicle. This device supplies hydraulic fluid to the wheel cylinders provided in the respective wheels of the vehicle via a first passage near the fluid pressure generating source and a second passage communicating with the first passage through a valve. A hydraulic brake unit that applies a hydraulic braking force to the wheel, a regenerative brake unit that applies a driving force or a regenerative braking force to the wheel by a rotating electric machine, and a hydraulic braking force and a regenerative braking force according to a braking request from a driver. A cooperative control unit that determines a distribution ratio of the hydraulic brake unit and requests a braking force to the regenerative brake unit and the hydraulic brake unit. The cooperative control unit is configured to compensate for a lack of hydraulic braking force at the initial stage of braking due to a response delay when a difference occurs in the hydraulic pressure increase response in the first passage and the second passage. The regenerative brake unit is commanded to apply a driving force or a regenerative braking force by the rotating electrical machine to the wheels.

  According to this aspect, when a difference occurs in the hydraulic braking force generated in the wheel corresponding to each passage due to the pressure increase response characteristics of the hydraulic pressure in the first passage and the second passage, the difference in the hydraulic braking force is compensated. In addition, the distribution of the driving force or regenerative braking force by the rotating electric machine to each wheel is determined. As a result, the variation in braking force between the wheels corresponding to each passage is alleviated, and the running stability of the vehicle is further improved.

  The regenerative brake unit is driven by a first rotating electrical machine provided on a wheel corresponding to the first passage, a second rotating electrical machine provided on a wheel corresponding to the second passage, and the first and second rotating electrical machines. You may have a battery which supplies electric power and stores regenerative electric power, and a rotary electric machine control part which controls operation of the 1st and 2nd rotary electric machines. The cooperative control unit includes a response difference estimation unit that estimates a difference in pressurization response of the hydraulic fluid pressure in the first passage and the second passage, and the first and second rotations according to the difference in pressurization response. And a regenerative braking force setting unit that calculates a regenerative braking force applied to the wheels by the electric machine.

  As an example, the “first rotating electrical machine” corresponds to the rear wheel motor of the embodiment, the “second rotating electrical machine” corresponds to the front wheel motor of the embodiment, and the “rotating electrical machine control unit” corresponds to the motor ECU.

  The cooperative control unit further includes a battery monitoring unit that detects the state of the battery, and instructs the rotating electrical machine control unit not to generate a regenerative braking force when the battery is fully charged. The pressure brake unit may be commanded to temporarily limit the flow of hydraulic fluid into the wheel cylinder communicating with the first passage. In this way, the hydraulic fluid whose flow into the first passage is restricted flows into the wheel cylinder that communicates with the second passage, so that the pressure increase response delay in the second passage can be improved. Therefore, the variation in braking force between the wheels corresponding to the respective passages due to the difference in boosting response is alleviated.

  The cooperative control unit applies a regenerative braking force to the wheel by the second rotating electrical machine to the rotating electrical machine control unit when the battery is fully charged, and a battery monitoring unit that detects the state of the battery. And a braking / driving force balance unit that commands to consume power generated by regenerative braking of the second rotating electrical machine and apply driving force to the wheels by the first rotating electrical machine. That is, a regenerative braking force is generated in the second rotating electrical machine corresponding to the second passage having a slow boost response, and a driving force is generated in the first rotating electrical machine corresponding to the first passage having a fast boosting response. If it carries out like this, since the regenerative electric power of a 2nd rotary electric machine is used as a drive force of a 1st rotary electric machine, it becomes unnecessary for a battery to receive electric power. Therefore, even when the battery is fully charged, it is possible to perform control for adjusting the regenerative braking force of the front and rear wheels so as to compensate for the hydraulic braking force difference between the front and rear wheels.

  When a regenerative braking force that compensates for a lack of hydraulic braking force cannot be applied to the wheel, a regenerative braking force is applied to the wheel by the second rotating electrical machine to the rotating electrical machine control unit, and the regenerative braking of the second rotating electrical machine is performed. A braking / driving force balance unit may be further provided that instructs the first rotating electrical machine to apply a driving force to the wheels while consuming the electric power generated by the first rotating electric machine.

  The regenerative brake unit includes a rotating electrical machine provided on a wheel corresponding to the second passage, a battery that supplies driving power to the rotating electrical machine and stores regenerative power, and a rotating electrical machine control that controls the operation of the rotating electrical machine. And may have a part. The cooperative control unit is provided to the wheel by the rotating electrical machine according to the difference in pressure increase response, and a response difference estimation unit that estimates a difference in pressure increase response of the hydraulic fluid pressure in the first passage and the second passage. And a regenerative braking force setting unit that calculates a regenerative braking force to be performed. According to this aspect, in the front-wheel drive hybrid vehicle, the difference in the total braking force between the front and rear wheels in the initial stage of braking is alleviated because the regenerative braking force of the front wheels compensates for the difference in hydraulic braking force between the front and rear wheels in the initial stage of braking. The running stability of the vehicle during braking can be improved.

  The regenerative brake unit may have a configuration in which an output shaft of the first rotating electrical machine, the second rotating electrical machine, and the engine is connected to an axle of a wheel corresponding to the second passage via a transmission. The cooperative control unit applies regenerative braking force to the wheels by the first rotating electrical machine, consumes electric power generated by the regenerative braking of the first rotating electrical machine, and rotates the output shaft of the engine by the second rotating electrical machine. You may control to make it. In this case, the first rotating electrical machine is generated by the rotational energy of the wheels. The second rotating electric machine is driven with this electric power, and the engine is idled. As a result, a regenerative braking force is applied by the first rotating electrical machine, and the electric power generated by the first rotating electrical machine is consumed by the second rotating electrical machine. Therefore, even when the battery is fully charged, it is possible to perform control for adjusting the regenerative braking force of the front wheels so as to compensate for the hydraulic braking force difference between the front and rear wheels.

  The response difference estimation unit includes a time change rate calculation unit that calculates a time change rate of a brake pedal stroke operated by a driver, and hydraulic fluid in the first passage and the second passage according to the calculated time change rate. And an estimated value storage unit in which an estimated value of a difference in pressure responsiveness of pressure is stored in advance. Since the difference in pressurization responsiveness between the first passage and the second passage changes depending on braking speed, by preparing an estimated value of the difference in pressurization responsiveness for each time change rate of the stroke, the hydraulic braking force difference Can be compensated more accurately.

  Another aspect of the present invention is also a vehicle braking device. This device is a vehicle braking device that includes a cooperative control unit that determines a distribution ratio between a hydraulic braking force and a regenerative braking force in response to a braking request from a driver and requests the braking force to the hydraulic brake unit and the regenerative braking unit. is there. The hydraulic brake unit includes a hydraulic pressure generating source capable of supplying hydraulic fluid having a pressure corresponding to the braking request, a wheel cylinder provided corresponding to each of the plurality of wheels, and exerting a braking force by increasing pressure. A pressure increase control valve for supplying hydraulic fluid from the hydraulic pressure generation source to the wheel cylinders according to operation of a brake pedal, a pressure reduction control valve for discharging hydraulic fluid from the wheel cylinders, Of these, a first passage comprising a flow passage communicating with the one close to the pressure increase control valve, a second passage comprising a passage communicating with the remaining wheel cylinder, and a communication passage between the first passage and the second passage. And a communication valve for separating the passages as necessary, and a hydraulic fluid to each wheel cylinder provided in a flow passage communicating from the first passage or the second passage to the wheel cylinders. Having a holding valve for controlling the supply, and a valve controller for controlling opening and closing of the valve, the. The regenerative brake unit is driven by a first rotating electrical machine provided on a wheel corresponding to the first passage, a second rotating electrical machine provided on a wheel corresponding to the second passage, and the first and second rotating electrical machines. A battery that supplies electric power and stores regenerative power; and a rotating electrical machine control unit that controls operations of the first and second rotating electrical machines. The cooperative control unit rotates the rotation so as to compensate for a lack of hydraulic braking force at the initial stage of braking due to a response delay when a difference occurs in the hydraulic fluid pressure increase response in the first passage and the second passage. A driving force or regenerative braking force by an electric machine is applied to the wheels.

  According to the present invention, in a vehicle including a hydraulic brake unit in which hydraulic fluid is supplied from a single hydraulic pressure generation source to a plurality of passages communicating with different wheels, the hydraulic pressure response difference between the passages is generated. The braking force difference between the wheels can be reduced.

Embodiment 1. FIG.
One embodiment of the present invention includes a hydraulic brake unit that supplies hydraulic fluid to a wheel cylinder provided on each wheel of a vehicle from a hydraulic pressure generation source and applies a braking force to the wheel, and a rotating electrical machine (hereinafter simply referred to as “motor”). It is related with the vehicle braking device applied to a hybrid vehicle provided with the regenerative brake unit which provides a driving force or a regenerative braking force to a wheel. Due to the characteristics of the hydraulic fluid passage of the hydraulic brake unit, the vehicle braking device can adjust the braking force by adjusting the front and rear wheel distribution of the braking force by regenerative braking when the braking force becomes transiently uneven at the front and rear wheels. Operates to make up for the shortage. As a result, the difference in braking force between the front and rear wheels during vehicle braking can be reduced, and the running stability of the vehicle is improved.

  Below, the structure of the hybrid vehicle which concerns on this embodiment is described first, and the structure of the hydraulic brake unit mounted in a hybrid vehicle is described next. Subsequently, a method for compensating for the hydraulic braking force difference between the front and rear wheels, which is a feature of the present embodiment, will be described in detail.

  FIG. 1 is a schematic configuration diagram illustrating a vehicle 100 to which the vehicle braking device according to the first embodiment is applied. The vehicle 100 is configured as a so-called hybrid vehicle, and can generate power connected to the engine 2, a three-shaft power split mechanism 3 connected to a crankshaft that is an output shaft of the engine 2, and the power split mechanism 3. A generator 4, a front wheel motor 6 connected to the power split mechanism 3 via the transmission 5, and a hybrid electronic control unit (hereinafter referred to as “hybrid ECU”) that controls the entire drive system of the vehicle 100, electronic control All the units are referred to as “ECU”) 7. A right front wheel 9FR and a left front wheel 9FL of the vehicle 100 are connected to the transmission 5 via a drive shaft 8.

  The engine 2 is an internal combustion engine that is operated using a hydrocarbon-based fuel such as gasoline or light oil, and is controlled by the engine ECU 10. The engine ECU 10 can communicate with the hybrid ECU 7, and performs fuel injection control, ignition control, intake control, etc. of the engine 2 based on control signals from the hybrid ECU 7 and signals from various sensors that detect the operating state of the engine 2. Execute. Further, the engine ECU 10 gives information about the operating state of the engine 2 to the hybrid ECU 7 as necessary.

  The vehicle 100 also includes a rear wheel motor 16. A right rear wheel 9RR and a left rear wheel 9RL of the vehicle 100 are connected to the transmission 15 via a drive shaft 18. The output of the rear wheel motor 16 is transmitted to the left and right rear wheels 9RR and 9RL via the transmission 15.

  The power split mechanism 3 transmits the output of the front wheel motor 6 to the left and right front wheels 9FR and 9FL via the transmission 5, distributes the output of the engine 2 to the generator 4 and the transmission 5, and the front wheel It plays the role of reducing or increasing the rotational speed of the motor 6 and the engine 2. The generator 4, the front wheel motor 6 and the rear wheel motor 16 are each connected to a battery 12 via a power converter 11 including an inverter, and a motor ECU 14 is connected to the power converter 11. The motor ECU 14 can also communicate with the hybrid ECU 7, and controls the generator 4, the front wheel motor 6, and the rear wheel motor 16 via the power conversion device 11 based on a control signal from the hybrid ECU 7. The hybrid ECU 7, engine ECU 10, and motor ECU 14 described above are all configured as a microprocessor including a CPU. In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, and an input / output port. And a communication port.

  Under the control of the hybrid ECU 7 and the motor ECU 14, power is supplied from the battery 12 to the front wheel motor 6 and the rear wheel motor 16 via the power converter 11, so that the left and right front wheels 9FR are output by the output of the front wheel motor 6. , 9FL can be driven, and the left and right rear wheels 9RR, 9RL can be driven by the output of the rear wheel motor 16. Further, the vehicle 100 is driven by the engine 2 in a driving region where the engine efficiency is good. At this time, by transmitting a part of the output of the engine 2 to the generator 4 via the power split mechanism 3, the front wheel motor 6 is driven using the electric power generated by the generator 4 or via the power converter 11. Thus, the battery 12 can be charged.

  When the vehicle 100 is braked, the front wheel motor 6 is rotated by the power transmitted from the front wheels 9FR and 9FL under the control of the hybrid ECU 7 and the motor ECU 14, and the front wheel motor 6 is operated as a generator. . Further, the rear wheel motor 16 is rotated by the power transmitted from the rear wheels 9RR and 9RL, and the rear wheel motor 16 is operated as a generator. That is, the front wheel motor 6, the rear wheel motor 16, the power converter 11, the hybrid ECU 7, the motor ECU 14, and the like function as a regenerative brake unit that brakes the vehicle 100 by regenerating the kinetic energy of the vehicle 100 into electrical energy. .

  The vehicle braking device of the present embodiment includes a hydraulic brake unit 20 in addition to such a regenerative brake unit, and can brake the vehicle 100 by executing brake regenerative cooperative control for coordinating both. is there. The cooperative control unit included in the hybrid ECU 7 determines a distribution ratio between the hydraulic braking force and the regenerative braking force in response to a braking request from the driver, and requests the braking force to the hydraulic brake unit 20 and the regenerative braking unit, respectively. .

  FIG. 2 shows the configuration of the hydraulic brake unit 20. The hydraulic brake unit 20 is used as a hydraulic fluid for the disc brake units 21FR, 21FL, 21RR and 21RL provided for the left and right front wheels 9FR, 9FL and the left and right rear wheels 9RR, 9RL, and the disc brake units 21FR to 21RL. The hydraulic pressure generating device 30 serving as a brake oil supply source and the hydraulic pressure of the brake oil from the hydraulic pressure generating device 30 are appropriately adjusted and supplied to the respective disc brake units 21FR to 21RL, whereby each wheel of the vehicle 100 is supplied. And a hydraulic actuator 40 capable of setting a braking force with respect to.

  Each of the disc brake units 21FR to 21RL includes a brake disc 22 and a brake caliper 23, and each brake caliper 23 incorporates a wheel cylinder (not shown). The wheel cylinder of each brake caliper 23 is connected to the hydraulic actuator 40 via an independent fluid passage. When brake oil is supplied from the hydraulic actuator 40 to the wheel cylinder of the brake caliper 23, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel, and hydraulic braking torque is applied to each wheel.

  As shown in FIG. 2, the hydraulic pressure generation device 30 includes a booster 31, a master cylinder 32, a regulator 33, a reservoir 34, an accumulator 35, and a pump 36. The booster 31 is connected to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, and transmits it to the master cylinder 32. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort. A brake stroke sensor 25 that detects an operation amount of the brake pedal 24 is provided for the brake pedal 24.

  A reservoir 34 for storing brake oil is disposed above the master cylinder 32 and the regulator 33. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 communicates with both the reservoir 34 and the accumulator 35, and the reservoir 34 is used as a low pressure source, and the accumulator 35 is used as a high pressure source. ").

  The accumulator 35 converts the pressure energy of the brake oil from the reservoir 34 boosted by the pump 36 into pressure energy (for example, about 14 to 22 MPa) of an enclosed gas such as nitrogen and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. For the accumulator 35, a relief valve 35a is provided. When the pressure of the brake oil in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake oil is returned to the reservoir 34.

  As described above, the hydraulic pressure generating device 30 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a brake oil supply source (hydraulic pressure source) for the disc brake units 21FR to 21RL. A fluid passage 37 is connected to the master cylinder 32, a fluid passage 38 is connected to the regulator 33, and a fluid passage 39 is connected to the accumulator 35. These fluid passages 37, 38 and 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of fluid passages are formed and a plurality of electromagnetic control valves. The fluid passage formed in the actuator block includes individual passages 41, 42, 43 and 44 and a main passage 45. The individual passages 41 to 44 are respectively branched from the main passage 45 and connected to the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Accordingly, each of the disc brake units 21FR to 21RL can communicate with the main passage 45. Further, in the middle of the individual passages 41, 42, 43 and 44, pressure increase holding valves 51, 52, 53 and 54 are provided. Each pressure-increasing holding valve 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and is a normally open electromagnetic control valve that is opened when the solenoid is in a non-energized state.

  Further, each of the disc brake units 21FR to 21RL is connected to the decompression passage 55 via decompression passages 46, 47, 48 and 49 connected to the individual passages 41 to 44, respectively. In the middle of the decompression passages 46, 47, 48 and 49, decompression control valves 56, 57, 58 and 59 are provided. Each pressure reduction control valve 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state.

  The main passage 45 has a communication valve 60 in the middle, and a first passage 45a connected to the individual passages 43 and 44 by the communication valve 60 and a second passage 45b connected to the individual passages 41 and 42. It is divided into. That is, the first passage 45a is connected to the rear wheel side disc brake units 21RR and 21RL via the individual passages 43 and 44, and the second passage 45b is connected to the front wheel side disc brake unit via the individual passages 41 and 42. Connected to 21FR and 21FL. The communication valve 60 is a normally closed electromagnetic control valve that has a solenoid and a spring that are ON / OFF controlled and is closed when the solenoid is in a non-energized state.

  The main passage 45 includes a master passage 61 connected to a fluid passage 37 communicating with the master cylinder 32, a regulator passage 62 connected to a fluid passage 38 communicating with the regulator 33, and a fluid passage 39 communicating with the accumulator 35. The accumulator passage 63 connected to the is connected. More specifically, the master passage 61 is connected to the second passage 45 b of the main passage 45, and the regulator passage 62 and the accumulator passage 63 are connected to the first passage 45 a of the main passage 45. Further, the decompression passage 55 is connected to the reservoir 34 of the hydraulic pressure generator 30.

  The master passage 61 has a master pressure cut valve 64 in the middle. The master pressure cut valve 64 has a solenoid and a spring that are ON / OFF controlled, and is a normally open electromagnetic control valve that is opened when the solenoid is in a non-energized state. The regulator passage 62 has a regulator pressure cut valve 65 in the middle. The regulator pressure cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and is a normally open electromagnetic control valve that is opened when the solenoid is in a non-energized state. The accumulator passage 63 has a pressure-increasing linear control valve 66 in the middle, and the accumulator passage 63 and the first passage 45 a of the main passage 45 are connected to the pressure reduction passage 55 via the pressure reduction linear control valve 67.

  The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the brake oil pressure in the accumulator 35 and the brake oil pressure in the main passage 45, and between the inlet and outlet of the pressure-reducing linear control valve 67. The differential pressure corresponds to the differential pressure between the brake oil pressure in the main passage 45 and the brake oil pressure in the decompression passage 55. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  Since the pressure-increasing linear control valve 66 is a normally closed electromagnetic control valve as described above, when the pressure-increasing linear control valve 66 is in a non-energized state, the main passage 45 has an accumulator as a high-pressure hydraulic pressure source. It will be cut off from 35. Since the pressure-reducing linear control valve 67 is also a normally closed electromagnetic control valve as described above, the main passage 45 is blocked from the reservoir 34 when the pressure-reducing linear control valve 67 is in a non-energized state. In this respect, it can be said that the main passage 45 is also connected to the reservoir 34 as a low pressure hydraulic pressure source.

  On the other hand, a stroke simulator 69 is connected to the master passage 61 via a stroke simulator cut valve 68 on the upstream side of the master pressure cut valve 64. The stroke simulator cut valve 68 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. The stroke simulator 69 includes a plurality of pistons and springs, and creates a reaction force corresponding to the depression force of the brake pedal 24 by the driver when the stroke simulator cut valve 68 is opened. As the stroke simulator 69, one having multi-stage spring characteristics is preferably employed in order to improve the feeling of brake operation by the driver, and the stroke simulator 69 of this embodiment has four stages of spring characteristics.

  The hydraulic pressure generator 30 and the hydraulic actuator 40 configured as described above are controlled by a brake ECU 70 as control means. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM for storing various programs, a RAM for temporarily storing data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 is communicable with the hybrid ECU 7, and an electromagnetic control valve constituting the pump 36 of the hydraulic pressure generating device 30 and the hydraulic actuator 40 based on control signals from the hybrid ECU 7 and signals from various sensors. 51 to 54, 56 to 59, 60, and 64 to 68 are controlled.

  Sensors connected to the brake ECU 70 include a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73. The regulator pressure sensor 71 detects the pressure of the brake oil (regulator pressure) in the regulator passage 62 on the upstream side of the regulator pressure cut valve 65, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure (accumulator pressure) of the brake oil in the accumulator passage 63 on the downstream side of the pressure-increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake oil in the second passage 45b of the main passage 45, and gives a signal indicating the detected value to the brake ECU 70. The detection values of the sensors 71 to 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area (buffer) of the brake ECU 70 by a predetermined amount.

  When the communication valve 60 is opened and the first passage 45a and the second passage 45b of the main passage 45 communicate with each other, the output value of the control pressure sensor 73 is the hydraulic pressure on the low pressure side of the pressure-increasing linear control valve 66. And the hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 is indicated, so that this output value can be used for controlling the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. Further, the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 are closed, and the communication valve 60 is in a non-energized state, so that the first passage 45a and the second passage 45b of the main passage 45 are separated from each other. If so, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the communication valve 60 is opened so that the first passage 45a and the second passage 45b of the main passage 45 communicate with each other, and the pressure increase holding valves 51 to 54 are opened, while the pressure reduction control valves 56 to 54 are opened. When 59 is closed, the output value of 73 of the control pressure sensor indicates the brake pressure (wheel cylinder pressure) of each of the disc brake units 21FR to 21RL.

  Further, the sensor connected to the brake ECU 70 includes the brake stroke sensor 25 described above. The brake stroke sensor 25 detects the operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The detection value of the brake stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held by a predetermined amount in a predetermined storage area (buffer) of the brake ECU 70. In addition to the brake stroke sensor 25, a pedal depression force sensor that detects an operation state of the brake pedal 24 and a brake switch that detects that the brake pedal 24 is depressed may be connected to the brake ECU 70.

  In the hydraulic brake unit 20 as described above, when the brake pedal 24 is operated by the driver and a braking request is made, the following operation is performed at normal times. First, both the master pressure cut valve 64 and the regulator pressure cut valve 65 are closed, and the stroke simulator cut valve 68 and the communication valve 60 are opened. Further, while the pressure increase holding valves 51 to 54 are opened, the pressure reduction control valves 56 to 59 are closed, and the supply current I to the linear solenoids of the pressure increase linear control valve 66 and the pressure reduction linear control valve 67 is controlled.

  Each of the disc brake units 21FR to 21RL is disconnected from both the master cylinder 32 and the regulator 33, and communicated with the accumulator 35 through the pressure-increasing linear control valve 66 and the like. The brake pressure (wheel cylinder pressure) in each of the disc brake units 21FR to 21RL controls the supply current I to the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 based on the output value of the control pressure sensor 73. It is adjusted by. In this case, the master cylinder 32 and the stroke simulator 69 are connected via the stroke simulator cut valve 68, and the reaction force for the driver who operates the brake pedal 24 is created by the stroke simulator 69. As described above, it is possible to stably supply brake oil having a desired pressure to each of the disc brake units 21FR to 21RL.

  By the way, in the hydraulic brake unit 20 described above, the brake pressure of the four-wheel disc brake units 21FR to 21RL is controlled by using one pressure-increasing linear control valve 66 and one pressure-decreasing linear control valve 67. Further, there is communication between the first passage 45a communicating with the wheel cylinders of the disc brake units 21RL and 21RR on the rear wheel side and the second passage 45b communicating with the wheel cylinders of the disc brake units 21FL and 21FR on the front wheel side. A valve 60 is provided. With such a configuration, the number of linear control valves required for realizing the pressure increase / decrease control can be reduced, so that the cost of the hydraulic brake unit 20 can be suppressed.

  However, in the above configuration, the brake oil from the accumulator 35 serving as a hydraulic pressure source once flows into the first passage 45a and then flows into the second passage 45b through the communication valve 60. Then, the communication valve 60 acts as an orifice, and the pressure increase of the second passage 45b on the front wheel side located farther from the pressure increasing linear control valve 66 with respect to the first passage 45a on the rear wheel side is delayed. Arise. This problem is particularly noticeable when the brake pedal is stepped on rapidly and the pressure increase gradient is high.

  FIG. 3 is a graph showing the relationship between the rear-wheel braking force and the front-wheel braking force generated by the hydraulic brake unit 20 when the brake pedal is operated. Generally, as indicated by a dotted line A in FIG. 3, it is desirable that the braking force of the front wheels and the braking force of the rear wheels increase with a constant ratio. However, when the brake pedal is suddenly depressed, the pressure increase in the second passage 45b on the front wheel side is delayed with respect to the pressure increase in the first passage 45a on the rear wheel side, as described above, so In a small region, as shown by a solid line B in FIG. 3, the rise of the braking force of the front wheels is slower than the increase of the braking force of the rear wheels, and the rear wheel is put in a state of greater braking. In other words, until the response delay is resolved between the rear wheels corresponding to the disc brake units 21RL and 21RR communicating with the first passage 45a and the front wheels corresponding to the disc brake units 21FL and 21FR communicating with the second passage 45b. During this time, the braking force generated on the wheels will be different. The deviation of the braking force between the front wheels and the rear wheels becomes larger as the braking becomes steep.

  Therefore, in the present embodiment, the regenerative braking force generated by the regenerative brake unit in order to compensate for the difference in the hydraulic braking force between the front and rear wheels caused by the pressure increase response delay of the second passage 45b on the front wheel side is shown in FIG. By distributing the front and rear wheels as indicated by the chain line C, the characteristics of the braking force of the vehicle as a whole are brought closer to the dotted line A. This further improves the running stability of the vehicle during braking.

  FIG. 4 is a functional block diagram illustrating a configuration of a cooperative control unit involved in cooperative control of the hydraulic brake unit and the regenerative brake unit according to the present embodiment in the hybrid ECU 7. Each block shown here can be realized in terms of hardware by elements and electric circuits including a computer CPU and memory, and in terms of software by a computer program or the like. It is drawn as a functional block to be realized. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  When there is a difference in the hydraulic fluid pressurization response in the first passage 45a and the second passage 45b of the hydraulic brake unit 20, the cooperative control unit 102 determines that the hydraulic braking force is insufficient at the initial stage of braking due to the response delay. Implement supplementary control.

The braking request determination unit 104 receives the stroke _Sps detected by the brake stroke sensor 25 via the brake ECU 70. The braking request determination unit 104 determines that a braking request has been made by the driver when the stroke _Sps is equal to or greater than a predetermined threshold value.

The response difference estimation unit 110 estimates a difference in the hydraulic fluid pressure increase response in the first passage 45a and the second passage 45b of the hydraulic brake unit 20.
The time change rate calculation unit 112 calculates the time change rate of the stroke _Sps of the brake pedal 24. If the time change rate is relatively large, it can be determined that the braking is sudden, and if the time change rate is relatively small, it can be determined that the braking is gentle. In the estimated value storage 116, when a hydraulic braking force determined according to the absolute value of the stroke is applied between the front and rear wheels, the estimated value storage unit 116 has a difference in the hydraulic fluid pressure increase response in the first passage 45a and the second passage 45b. The estimated value of the difference in the hydraulic braking force generated between the front and rear wheels is stored in advance in a map format. This map is preferably prepared for each time change rate of the stroke. The estimated value can be obtained for each vehicle type through simulations and experiments. The hydraulic braking force difference estimation unit 114 receives the time change rate of the stroke from the time change rate calculation unit 112 and searches the map in the estimated value storage unit 116 to obtain the difference in hydraulic braking force between the corresponding front and rear wheels. .

The braking force calculation unit 120 calculates a required regenerative braking force commanded to the motor ECU 14 and a requested hydraulic pressure braking force commanded to the brake ECU 70.
The regenerative braking force setting unit 122 applies the front wheels 9FR and 9FL or the rear wheels 9RR and 9RL by the regenerative brake unit so as to compensate for the difference in hydraulic braking force between the front and rear wheels obtained by the hydraulic braking force difference estimation unit 114. Set the required regenerative braking force to be applied.
The hydraulic braking force setting unit 124 gives the front wheels 9FR, 9FL, rear wheels 9RR, 9RL by the hydraulic brake unit 20 by subtracting the required regenerative braking force from the total braking force requested by the driver by operating the brake pedal. Set the required hydraulic braking force.

  The battery monitoring unit 130 detects the state of charge of the battery 12 and supplies the power storage side upper limit value, which is an upper limit value determined based on the charge capacity of the battery 12, to the braking force calculation unit 120. Further, the motor ECU 14 supplies the braking force calculation unit 120 with a power generation side upper limit value that is an upper limit value of the regenerative braking force determined based on the rotational speeds of the front wheel motor 6 and the rear wheel motor 16.

  The regenerative braking force setting unit 122 may have a function of determining whether or not the front wheel motor 6 or the rear wheel motor 16 can generate the required regenerative braking force based on these values. When the regenerative braking force cannot be generated, the battery 12 is in a fully charged state and the regenerative power generated by the front wheel motor 6 or the rear wheel motor 16 cannot be accepted, or the required regenerative braking force is for the front wheel. In some cases, the motor 6 or the rear wheel motor 16 has a size that cannot be generated due to the rating.

  When the required regenerative braking force can be generated, the required hydraulic braking force obtained by the hydraulic braking force setting unit 124 is transmitted to the brake ECU 70, and the required regenerative braking force obtained by the regenerative braking force setting unit 122 is transmitted to the motor ECU 14. Is done.

  When the required regenerative braking force cannot be generated, the hydraulic braking force recalculation unit 134 recalculates the required hydraulic braking force so as to achieve the total braking force required only by the hydraulic brake unit 20. The calculated required hydraulic braking force is transmitted to the brake ECU 70.

  The motor braking / driving force balance unit 136 applies regenerative braking force to the front wheels 9FR and 9FL by the front wheel motor 6 and consumes electric power generated by the regenerative braking of the front wheel motor 6, and the rear wheel motor 16 The motor ECU 14 is commanded to apply driving force to the wheels 9RR and 9RL.

  The brake ECU 70 calculates the target hydraulic pressure of each of the disc brake units 21FR to 21RL based on the required hydraulic braking force output from the cooperative control unit 102, and supplies current to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67. Determine the value of I.

  The motor ECU 14 sends control signals for the front wheel motor 6 and the rear wheel motor 16 to the power converter 11 based on the required driving force or the required regenerative braking force output from the cooperative control unit 102.

  FIGS. 5A and 5B are diagrams for explaining how the regenerative braking force of the front and rear wheels is adjusted in order to compensate for the lack of hydraulic braking force at the initial stage of braking. FIG. 5A shows the hydraulic braking force 150 of the rear wheel and the hydraulic braking force 152 of the front wheel at the initial braking stage when the brake is suddenly depressed. The dotted line in the figure indicates the required braking force. As shown in the figure, at the initial stage of braking, the hydraulic braking force of the front wheels becomes transiently smaller than the hydraulic braking force of the rear wheels due to the difference in the pressure increase response of the hydraulic fluid passage. Therefore, the regenerative braking force setting unit 122 determines the regenerative braking force 154 for the rear wheels and the regenerative braking force 156 for the front wheels so as to compensate for the braking force difference D between the front and rear wheels.

  FIG. 6 is a flowchart of control executed by the cooperative control unit 102 of FIG. 4 to compensate for the difference in hydraulic braking force between the front and rear wheels. This routine is repeatedly executed by the hybrid ECU 7 every predetermined time.

First, when receiving the output value Sps of the brake stroke sensor 25 via the brake ECU 70 (S10), the braking request determination unit 104 determines whether the stroke Sps exceeds a predetermined threshold _{S t} (S12) . If it is less than or equal to the threshold value (N in S12), this routine is terminated. If the threshold is exceeded (Y in S12), it is determined that a braking request has been made by the driver. The time change rate calculation unit 112 calculates the time change rate dS _PS / dt of the stroke (S14). That is, the time change rate calculation unit 112 divides the value obtained by subtracting the previous value from the current value (latest value) of the output value of the brake stroke sensor 25 by the sampling period to thereby change the time change rate dS _PS / dt of the pedal stroke Sps. Is calculated. The hydraulic braking force difference estimation unit 114 refers to the map stored in the estimated value storage unit 116 according to the calculated time change rate dS _PS / dt of the stroke and the absolute value of the stroke, and the front and rear wheels at the initial stage of braking. The difference in the hydraulic braking force due to the difference in the pressurization response at is estimated (S16).

  Since the difference in the boost response in the first passage on the rear wheel side and the second passage on the front wheel side changes depending on the braking speed, the map in the estimated value storage unit 116 is prepared according to the time change rate of the stroke. Preferably it is. Note that the hydraulic braking force difference estimation unit 114 uses a predetermined approximate calculation formula using the time change rate of the stroke and the absolute value of the stroke as variables instead of using the map, and determines the difference in the boosting response between the front and rear wheels. You may estimate the difference of the hydraulic braking force resulting from this.

The braking force calculation unit 120 calculates a required total braking force based on a signal from the brake stroke sensor 25, and the regenerative braking force setting unit 122 compensates for the estimated difference in hydraulic braking force between the front wheels and the rear wheels. The required regenerative braking force to be applied to is obtained (S18). Further, the hydraulic braking force setting unit 124 calculates a required hydraulic braking force to be generated by the hydraulic brake unit 20 by subtracting the required regenerative braking force from the required total braking force.
Note that the difference in hydraulic braking force between the front and rear wheels occurs only during a period when the increase in brake hydraulic pressure at the initial stage of braking is steep, so the regenerative braking force on the front wheel side is quickly reduced after this period. It is desirable to change the required regenerative braking force so that

  The required regenerative braking force obtained in S18 is transmitted to the motor ECU 14, and the required hydraulic braking force is transmitted to the brake ECU 70 (S20). The motor ECU 14 regenerates the braking force applied to the left and right front wheels 9FR and 9FL by the front wheel motor 6 and the braking force applied to the left and right rear wheels 9RR and 9RL by the rear wheel motor 16. A control signal for matching the braking force is sent to the power converter 11. The brake ECU 70 calculates the target hydraulic pressure of each of the disc brake units 21FR to 21RL based on the calculated required hydraulic braking force, and determines the value of the supply current I for the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67.

  In this way, by adjusting the required regenerative braking force for the front and rear wheels, the difference in the hydraulic braking force between the front and rear wheels at the initial stage of braking is compensated, so the disparity in the total braking force between the front and rear wheels at the initial stage of braking is alleviated. The running stability of the vehicle at the time can be improved. This is the end of the description of the flowchart of FIG.

  The hydraulic braking force recalculation unit 134 instructs the brake ECU 70 not to generate a regenerative braking force when the battery is fully charged, and also instructs the brake ECU 70 to the first passage 45a of the hydraulic brake unit 20. It may be instructed to temporarily limit the flow of hydraulic fluid into the communicating wheel cylinder. This will be described with reference to FIG.

FIG. 7 is a flowchart of a modification in which the hydraulic braking force difference between the front and rear wheels in the initial stage of braking is alleviated by the control in the hydraulic brake unit 20 when the battery is fully charged.
S30 to S38 are the same as S10 to S18 in FIG. In S40, the regenerative braking force setting unit 122 refers to the power generation side upper limit value and the power storage side upper limit value to confirm whether or not the front wheel motor 6 and the rear wheel motor 16 can generate the required regenerative braking force. If regeneration is possible (Y in S40), the required regenerative braking force is commanded to the motor ECU 14 and the required hydraulic braking force is commanded to the brake ECU 70 (S42). If regenerative is impossible (N in S40), the hydraulic braking force recalculation unit 134 recalculates the required hydraulic braking force so that the total braking force can be provided only by the hydraulic braking force without performing regenerative braking ( S44). Then, the brake ECU 70 is instructed to intentionally delay the pressure increase response of the first passage 45a corresponding to the rear wheel for a certain period according to the hydraulic braking force difference estimated in S36 (S46).

  Specifically, in response to a command from the hydraulic braking force recalculating unit 134, the brake ECU 70 commands the pressure increase holding valves 53 and 54 communicating with the first passage 45a to be closed for a certain period. As a result, the flow of brake oil into the wheel cylinders of the disc brake units 21RL and 21RR communicating with the first passage 45a is temporarily restricted. Accordingly, the corresponding amount of brake oil flows into the second passage 45b, and the delay in boosting response of the second passage 45b, which is difficult to boost because it is located far from the accumulator as the hydraulic pressure source, is improved. Therefore, the variation in braking force between the wheels corresponding to each passage is reduced.

  According to this modification, even when the regenerative braking force that compensates for the hydraulic braking force difference cannot be generated because the battery 12 is fully charged, the boosting responsiveness is controlled by the control in the hydraulic brake unit 20. The difference can be mitigated.

FIG. 8 is a flowchart of another modified example for relaxing the hydraulic braking force difference between the front and rear wheels at the initial stage of braking when the battery is fully charged.
S50 to S58 are the same as S10 to S18 in FIG. In S62, the regenerative braking force setting unit 122 refers to the power generation side upper limit value and the power storage side upper limit value to confirm whether or not the front wheel motor 6 and the rear wheel motor 16 can generate the required regenerative braking force. If regeneration is possible (Y in S62), the required regenerative braking force is commanded to the motor ECU 14 and the required hydraulic braking force is commanded to the brake ECU 70 (S70). If regenerative is impossible (N in S62), the hydraulic braking force recalculation unit 134 recalculates the required hydraulic braking force so that the total braking force can be provided only by the hydraulic braking force without performing regenerative braking ( S64). The hydraulic braking force recalculation unit 134 further estimates the hydraulic braking force difference between the front and rear wheels (S66). This estimation may be based on a map obtained by an experiment in advance, or a predetermined approximate expression may be used.

  The motor braking / driving force balance unit 136 sets a value obtained by halving the estimated hydraulic braking force difference as the required regenerative braking force of the front wheels. Further, a value obtained by halving the hydraulic braking force difference is set as a required driving force for the rear wheels (S68). Then, the brake ECU 70 is instructed with the required hydraulic braking force calculated in S64, and the motor ECU 14 is instructed with the required regenerative braking force and the required driving force calculated in S68 (S70).

  At this time, the motor ECU 14 sends a control signal to the power converter 11 so that the electric power generated by the regenerative braking of the front wheel motor 6 is consumed as the driving power of the rear wheel motor 16. Thereby, since the regenerative electric power of the front wheel motor 6 is used as the driving force of the rear wheel motor 16, the battery 12 does not need to accept electric power. Therefore, even when the battery 12 is fully charged, it is possible to perform control for adjusting the regenerative braking force of the front and rear wheels so as to compensate for the hydraulic braking force difference between the front and rear wheels.

  The example with reference to FIG. 8 has been described as being performed when the battery 12 is fully charged. However, the hydraulic braking force difference between the front and rear wheels estimated by the hydraulic braking force difference estimation unit 114 is generated by the regenerative braking force. Similar control can be performed even when the upper limit is exceeded.

  This modification will be described with reference to FIG. FIGS. 9A and 9B are diagrams for explaining how the regenerative braking force of the front and rear wheels is adjusted in order to compensate for the lack of the hydraulic braking force at the initial stage of braking. When the difference E between the hydraulic braking force 160 of the rear wheels and the hydraulic braking force 162 of the front wheels exceeds the upper limit value 164 that can be generated by the front wheel motor 6 in the initial braking period when the brake is suddenly depressed (see FIG. 9A). )think of. At this time, the hydraulic braking force recalculation unit 134 is configured so that the excess value of the rear wheel hydraulic braking force exceeding the required braking force and the insufficient value of the front wheel hydraulic braking force less than the required braking force substantially coincide. The front and rear wheel hydraulic braking forces 160 ′ and 162 ′ are set. Then, the motor braking / driving force balance unit 136 requests the rear wheel motor 16 for the driving force 166 so as to cancel out the excess hydraulic braking force for the rear wheel, and for the front wheel, the insufficient liquid pressure. A regenerative braking force 168 is requested to the front wheel motor 6 so as to supplement the pressure braking force. By so doing, even when the estimated hydraulic braking force difference between the front and rear wheels exceeds the upper limit value of the regenerative braking force, it is possible to realize control that compensates for the hydraulic braking force difference between the front and rear wheels.

  As described above, according to the first embodiment, in the early stage of braking when the brake is suddenly depressed, the pressure increase response of the second passage on the front wheel side is delayed with respect to the first passage on the rear wheel side in the hydraulic brake unit, When the hydraulic braking force of the front wheel is insufficient with respect to the rear wheel, the regenerative braking force of the front and rear wheels is adjusted so as to fill in the hydraulic braking force difference. As a result, the stability of the vehicle during sudden braking can be improved.

Embodiment 2. FIG.
FIG. 10 is a schematic configuration diagram showing a vehicle 200 to which a vehicle braking device according to another embodiment of the present invention is applied. The vehicle 200 is the same as the vehicle 100 shown in FIG. 1 except that it does not have the rear wheel motor 16 and the transmission 15. That is, the vehicle 200 is a front-wheel drive hybrid vehicle. The configuration of the cooperative control unit (not shown) in the hybrid ECU 7 is the same as that of the cooperative control unit 102 shown in FIG. 4, but in the second embodiment, the regenerative braking force is calculated only for the front wheel motor 6. The point is different.

  FIG. 11 is a flowchart of control for compensating for the difference in hydraulic braking force between the front and rear wheels, which is executed by the cooperative control unit. This routine is repeatedly executed by the hybrid ECU 7 every predetermined time.

First, when receiving the output value Sps of the brake stroke sensor 25 via the brake ECU 70 (S80), the braking request determination unit 104 determines whether the stroke Sps exceeds a predetermined threshold _{S t} (S82) . If it is equal to or less than the threshold value (N in S82), this routine is terminated. If the threshold value is exceeded (Y in S82), it is determined that a braking request has been made by the driver. The time change rate calculation unit 112 calculates the time change rate dS _PS / dt of the stroke (S84). The hydraulic braking force difference estimation unit 114 refers to the map stored in the estimated value storage unit 116 according to the calculated time change rate dS _PS / dt of the stroke and the absolute value of the stroke, and determines the vehicle in the initial stage of braking. A difference in hydraulic braking force due to a difference in pressure increase response between the front and rear wheels is estimated (S86). Up to this point, the process is the same as S10 to S16 in FIG.

  The braking force calculation unit 120 calculates a required total braking force based on a signal from the brake stroke sensor 25, and the regenerative braking force setting unit 122 applies the difference to the estimated hydraulic braking force to the front wheels. A required regenerative braking force is obtained (S88). Further, the hydraulic braking force setting unit 124 calculates a required hydraulic braking force to be generated by the hydraulic brake unit 20 by subtracting the required regenerative braking force from the required total braking force. Also in this case, the difference in hydraulic braking force between the front and rear wheels occurs only during a period when the increase in the brake hydraulic pressure at the initial stage of braking is steep, so that the regenerative braking force on the front wheel side is quickly increased after this period. It is desirable to change the required regenerative braking force so as to decrease it.

  The required regenerative braking force obtained in S88 is transmitted to the motor ECU 14, and the required hydraulic braking force is transmitted to the brake ECU 70 (S90). The motor ECU 14 sends a control signal for making the braking force applied to the left and right front wheels 9FR, 9FL by the front wheel motor 6 coincide with the required regenerative braking force to the power converter 11. The brake ECU 70 calculates the target hydraulic pressure of each of the disc brake units 21FR to 21RL based on the calculated required hydraulic braking force, and determines the value of the supply current I for the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67.

  As described above, also in the second embodiment, the difference between the hydraulic braking forces of the front and rear wheels at the initial stage of braking is compensated by the regenerative braking force of the front wheels. The running stability of the vehicle at the time can be improved.

FIG. 12 is a flowchart of a modified example in which the hydraulic braking force difference between the front and rear wheels at the initial stage of braking is reduced when the battery is fully charged.
S100 to S108 are the same as S80 to S88 in FIG. In S112, the regenerative braking force setting unit 122 refers to the power generation side upper limit value and the power storage side upper limit value to check whether or not the front wheel motor 6 can generate the required regenerative braking force. If regeneration is possible (Y in S112), the required regenerative braking force is commanded to the motor ECU 14 and the required hydraulic braking force is commanded to the brake ECU 70 (S116).

If regeneration is not possible (N in S112), the motor braking / driving force balance unit 136 performs the following control. That is, a regenerative braking force is generated by causing the rotational force of the front wheels 9FR and 9FL to be applied to the generator 4 by the power split mechanism. The regenerative power of the generator 4 is sent to the front wheel motor 6 via the power converter 11, and this power is consumed to drive the front wheel motor 6 (S114). Then, control is performed so that the engine is idled via the power split mechanism 3 by the driving force of the motor. Thereby, the work of the generator can be generated as a regenerative braking force.
As a result, even when the battery 12 is fully charged, it is possible to perform control to compensate for the hydraulic braking force difference between the front and rear wheels.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art. Moreover, what changed the order of the process of this invention is also effective as an aspect of this invention.

  In the embodiment, a hybrid vehicle having a motor and a generator separately on the front wheel side of the vehicle has been described. However, the present invention is also applied to a hybrid vehicle in which one rotating electric machine is shared as a generator and a motor. Is possible.

It is a schematic block diagram which shows the hybrid vehicle to which the vehicle braking device which concerns on Embodiment 1 was applied. It is a figure which shows the structure of the hydraulic brake unit of FIG. It is a graph which shows the relationship between the rear-wheel side braking force and the front-wheel side braking force when a brake pedal is operated. It is a functional block diagram which shows the structure of the cooperative control part in connection with the cooperative control of the hydraulic brake unit and regenerative brake unit which concern on this embodiment among hybrid ECUs. (A), (b) is a figure explaining a mode that the regenerative braking force of a front-and-rear wheel is adjusted in order to compensate for the lack of the hydraulic braking force at the initial stage of braking. 4 is a flowchart of control for reducing a difference in hydraulic braking force between front and rear wheels, which is executed by the cooperative control unit of the first embodiment. It is a flowchart of the modification which relieve | moderates the hydraulic-braking force difference of the front-and-rear wheels of the initial stage of braking when the battery is fully charged. FIG. 10 is a flowchart of another modified example in which the hydraulic braking force difference between the front and rear wheels in the initial stage of braking is reduced when the battery is fully charged. (A), (b) is a figure explaining a mode that the regenerative braking force of a front-and-rear wheel is adjusted in order to compensate for the lack of the hydraulic braking force at the initial stage of braking. It is a schematic block diagram which shows the hybrid vehicle to which the vehicle braking device which concerns on Embodiment 2 was applied. 10 is a flowchart of control for reducing a difference in hydraulic braking force between front and rear wheels, which is executed by the cooperative control unit of the second embodiment. It is a flowchart of the modification which relieve | moderates the hydraulic-braking force difference of the front-and-rear wheels of the initial stage of braking when the battery is fully charged.

Explanation of symbols

  2 engine, 3 power split mechanism, 4 generator, 5 transmission, 6 front wheel motor, 7 hybrid ECU, 12 battery, 14 motor ECU, 15 transmission, 16 rear wheel motor, 20 hydraulic brake unit, 21 disc brake Unit, 24 brake pedal, 25 brake stroke sensor, 30 hydraulic pressure generator, 40 hydraulic actuator, 45a first passage (rear wheel side), 45b second passage (front wheel side), 60 communication valve, 70 brake ECU, 100 , 200, vehicle, 102 cooperative control unit, 104 braking request determination unit, 110 response difference estimation unit, 112 time change rate calculation unit, 114 hydraulic braking force difference estimation unit, 116 estimated value storage unit, 120 braking force calculation unit, 122 Regenerative braking force setting unit, 124 A hydraulic braking force setting unit; 130 a battery monitoring unit; 134 a hydraulic braking force recalculation unit; and 136 a motor braking / driving force balance unit.

Claims (9)

A vehicle braking device for braking a vehicle,
The hydraulic fluid is supplied to a wheel cylinder provided in each wheel of the vehicle via a first passage near the fluid pressure generation source and a second passage communicating with the first passage through a valve. A hydraulic brake unit that applies pressure braking force;
A regenerative brake unit that applies driving force or regenerative braking force to the wheels by a rotating electric machine;
A coordination control unit that determines a distribution ratio between a hydraulic braking force and a regenerative braking force in response to a braking request from a driver and requests the braking force from the hydraulic brake unit and the regenerative brake unit;
The cooperative control unit rotates the rotation so as to compensate for a lack of hydraulic braking force at the initial stage of braking due to a response delay when a difference occurs in the hydraulic fluid pressure increase response in the first passage and the second passage. A vehicle braking device characterized by instructing the regenerative brake unit to apply a driving force or a regenerative braking force by an electric machine to the wheels. The regenerative brake unit is
A first rotating electrical machine provided on a wheel corresponding to the first passage;
A second rotating electrical machine provided on a wheel corresponding to the second passage;
A battery for supplying driving power to the first and second rotating electrical machines and storing regenerative power;
A rotating electrical machine control unit that controls operations of the first and second rotating electrical machines,
The cooperative control unit
A response difference estimator for estimating a difference in pressure-responsiveness of hydraulic fluid pressure in the first passage and the second passage;
A regenerative braking force setting unit that calculates a regenerative braking force applied to the wheels by the first and second rotating electrical machines according to a difference in boosting response;
The vehicle braking device according to claim 1, comprising:   The cooperative control unit further includes a battery monitoring unit that detects the state of the battery, and instructs the rotating electrical machine control unit not to generate a regenerative braking force when the battery is fully charged. 3. The vehicle braking apparatus according to claim 2, wherein the pressure brake unit is instructed to temporarily restrict the inflow of hydraulic fluid into a wheel cylinder communicating with the first passage. The cooperative control unit
A battery monitoring unit for detecting the state of the battery;
When the battery is fully charged, the regenerative braking force is applied to the wheel by the second rotating electrical machine to the rotating electrical machine control unit, and the electric power generated by the regenerative braking of the second rotating electrical machine is consumed. A braking / driving force balance unit instructing to apply driving force to the wheels by the first rotating electrical machine;
The vehicle braking device according to claim 2, further comprising:   When the regenerative braking force that compensates for the lack of hydraulic braking force cannot be applied to the wheel, the cooperative control unit applies the regenerative braking force to the wheel by the second rotating electrical machine to the rotating electrical machine control unit. 3. The braking / driving force balance unit that commands to consume power generated by regenerative braking of the two-rotating electric machine and apply driving force to the wheels by the first rotating electric machine. 4. Vehicle braking device. The regenerative brake unit is
A rotating electrical machine provided on a wheel corresponding to the second passage;
A battery for supplying driving power to the rotating electrical machine and storing regenerative power;
A rotating electrical machine control unit that controls the operation of the rotating electrical machine,
The cooperative control unit
A response difference estimator for estimating a difference in pressure-responsiveness of hydraulic fluid pressure in the first passage and the second passage;
A regenerative braking force setting unit for calculating a regenerative braking force applied to the wheel by the rotating electric machine according to a difference in boosting response;
The vehicle braking device according to claim 1, comprising: The regenerative brake unit has a configuration in which an output shaft of the first rotating electrical machine, the second rotating electrical machine, and the engine is connected to an axle of a wheel corresponding to the second passage through a power split mechanism,
The cooperative control unit applies regenerative braking force to the wheels by the first rotating electrical machine, consumes electric power generated by the regenerative braking of the first rotating electrical machine, and rotates the output shaft of the engine by the second rotating electrical machine. The vehicle braking device according to claim 1, wherein: The response difference estimator is
A time change rate calculating unit for calculating a time change rate of a stroke of a brake pedal operated by a driver;
An estimated value storage unit in which an estimated value of a difference in pressure-responsiveness of hydraulic fluid pressure in the first passage and the second passage according to the calculated time change rate is stored in advance;
The vehicle braking device according to any one of claims 2 to 7, further comprising: A vehicle braking device including a cooperative control unit that determines a distribution ratio between a hydraulic braking force and a regenerative braking force according to a braking request from a driver and requests a braking force to the hydraulic brake unit and the regenerative braking unit,
The hydraulic brake unit is
A hydraulic pressure generating source capable of supplying hydraulic fluid having a pressure corresponding to the braking request;
A wheel cylinder provided corresponding to each of the plurality of wheels and exhibiting a braking force by increasing pressure;
A pressure increase control valve for supplying hydraulic fluid from the hydraulic pressure generation source to the wheel cylinders according to operation of a brake pedal;
A pressure reducing control valve for discharging the hydraulic fluid from the wheel cylinder;
A first passage comprising a flow path communicating with the wheel cylinder in proximity to the pressure increase control valve;
A second passage comprising a flow path communicating with the remaining wheel cylinders;
A communication valve disposed in the communication passage between the first passage and the second passage, and separating the passages as necessary;
A holding valve that is disposed in a flow path that communicates with each wheel cylinder from the first passage or the second passage and controls the supply of hydraulic fluid to each wheel cylinder;
A valve control unit that controls opening and closing of the valve,
The regenerative brake unit is
A first rotating electrical machine provided on a wheel corresponding to the first passage;
A second rotating electrical machine provided on a wheel corresponding to the second passage;
A battery for supplying driving power to the first and second rotating electrical machines and storing regenerative power;
A rotating electrical machine control unit that controls operations of the first and second rotating electrical machines,
The cooperative control unit rotates the rotation so as to compensate for a lack of hydraulic braking force at the initial stage of braking due to a response delay when a difference occurs in the hydraulic fluid pressure increase response in the first passage and the second passage. A vehicle braking device that applies a driving force or a regenerative braking force by an electric machine to the wheels.

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