JP2003125501A - Degenerative brake device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform regenerative braking by effectively using regenerative power, even in a fully charged condition of a battery or in a condition close to it. SOLUTION: When a vehicle is decided to be in braking and further when a battery is decided incapable of being charged, an engine is stopped and an on-vehicle auxiliary apparatus is driven by driving a second motor by the regenerative power from a first motor. In this way, even if the battery is in a fully charged condition or in a condition close to full charge, a regenerative braking can be performed by effectively using the regenerative power, and the fuel consumption of a hybrid vehicle can be reduced comprehensively, in addition to stopping of the engine during braking.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a regenerative braking system for a hybrid vehicle.

[0002]

2. Description of the Related Art A regenerative braking device for an electric vehicle that performs regenerative braking by flowing a regenerative current to a discharge resistor instead of flowing a regenerative current to the battery when the battery is in a fully charged state or a state close to a fully charged state is known. (See, for example, Japanese Patent Laid-Open No. 08-051701).

[0003]

However, in the above-described conventional regenerative braking system for electric vehicles, the regenerative current is made to flow to the discharge resistor when the battery is in a fully charged state or a state close to a fully charged state. However, there is a problem that regenerative power becomes heat and is lost, so that it cannot be used effectively.

It is an object of the present invention to provide a regenerative braking system for a hybrid vehicle that performs regenerative braking while effectively utilizing regenerative power even when the battery is in a fully charged state or a state close to a fully charged state.

[0005]

According to a first aspect of the present invention, there is provided an engine for driving a vehicle to drive a vehicle-mounted accessory, a first motor for driving and braking a vehicle, and the engine. A second motor that drives an in-vehicle auxiliary device when stopped and a battery that supplies electric power to the first motor and the second motor to drive the vehicle, and the battery regenerated by the electric power regenerated from the first motor during braking. Motor driving means for charging, a braking determination means for determining whether the vehicle is braking, a charging availability determination means for determining whether the battery is chargeable or not, and the vehicle is determined to be braking, and When it is determined that the battery cannot be charged,
The control means for stopping the engine and driving the second motor with the regenerative electric power from the first motor to drive the vehicle-mounted auxiliary equipment is provided, thereby achieving the above object. (2) In the regenerative braking system for a hybrid vehicle according to claim 2, the braking determination means includes an accelerator operation detecting means for detecting a released state of the accelerator pedal and a brake operation detecting means for detecting a depressed state of the brake pedal. In addition, when the release state of the accelerator pedal is detected and the depression state of the brake pedal is detected, it is determined that the braking is being performed. (3) In the regenerative braking device for a hybrid vehicle according to claim 3, the chargeability determination means has an SOC detection means for detecting a state of charge (SOC) of the battery, and the charging is performed based on the detected SOC. The decision is made as to whether or not it is possible.

[0006]

According to the present invention, when it is determined that the vehicle is braking and the battery cannot be charged, the engine is stopped and the second motor is driven by the regenerative electric power from the first motor. Since we have done so to drive the in-vehicle auxiliary equipment, even when the battery is fully charged or near full charge, regenerative braking can be performed while making effective use of regenerative power, and along with stopping the engine during braking. The fuel consumption of the hybrid vehicle can be reduced overall.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a hybrid vehicle in which either or both of an engine and a motor are used as a travel drive source will be described. It should be noted that as long as it is a hybrid vehicle in which one or both of the engine and the motor are used as the traveling drive source, the hybrid vehicle can be applied to any hybrid vehicle having any configuration.

FIG. 1 shows the mechanical structure of one embodiment, and FIG. 2 shows the electrical structure of one embodiment. In FIG. 1, the engine ENG and the motor M1 are directly connected, and their braking / driving force is transmitted to the rear wheel R via the automatic transmission AT.
W is transmitted. Here, of course, the motor M1 can be used as a braking / driving source of the vehicle, but here it is mainly used for starting the engine ENG and for power generation. On the other hand, the braking / driving force of the motor M2 is transmitted to the front wheels FW.

That is, the vehicle according to the embodiment has the front wheels FW.
Is a four-wheel drive vehicle driven by a motor M2, and the rear wheels RW are mainly driven by an engine ENG, and travels using one or both of the engine ENG and the motor M2 as a braking / driving source. The engine ENG may drive the front wheels FW and the motor M2 may drive the rear wheels RW.

The engine ENG is connected to an accessory drive motor M3 via a pulley, a belt mechanism 1 and an electromagnetic clutch CL. In addition, the auxiliary drive motor M3
Is a power steering oil pump PSP, an air conditioner compressor C through a pulley and a belt mechanism 2.
It is connected to auxiliary equipment such as MP and automatic transmission oil pump ATP, and drives these auxiliary equipment. The onboard accessories are not limited to the accessories of the above-described embodiment.

Power steering oil pump PSP
Supplies oil to the power steering body (not shown), and the automatic transmission oil pump ATP supplies oil to the automatic transmission AT. The air conditioner / compressor CMP compresses the refrigerant of the air conditioner (air conditioner, not shown). The electromagnetic clutch CL connects and disconnects the engine ENG with the motor M3 and the auxiliary machines PSP, CMP, and ATP. In addition,
Instead of the electromagnetic clutch CL, a one-way clutch capable of transmitting power only from the engine ENG to the accessory drive motor M3 may be used.

The brake pedal 3 is connected to a booster (power booster) BST, and the booster BST generates a brake fluid pressure in which the depression force of the brake pedal 3 is increased. This brake fluid pressure is applied to the brake fluid pipe 4a,
4b is transmitted to the front brake FB of the front wheels FW and the rear brake RB of the rear wheels RW via the brake actuator ACT to brake the vehicle.

In FIG. 2, an accelerator sensor 5 detects a depression amount of an accelerator pedal (not shown) (hereinafter referred to as an accelerator opening), and a brake sensor 6 detects a depression amount of a brake pedal 3 (see FIG. 1). . The vehicle speed sensor 7 detects the traveling speed of the vehicle, and the shift sensor 8 is a shift lever (not shown) of the automatic transmission AT (see FIG. 1).
The setting position of is detected.

The vehicle controller 10 comprises a microcomputer and its peripheral parts, controls the battery controller 11, the motor controllers 12-14, the engine controller 15 and the brake controller 16 based on signals from various sensors 5-8, and also controls the electromagnetic waves. The clutch CL (see FIG. 1) is driven to control starting and stopping of the engine ENG, braking / driving force of the engine ENG and the motor M2, driving of an auxiliary machine by the motor M3, power generation by the motor M1, and the like.

The battery controller 11 detects the charge state SOC (State Of Charge) of the battery BAT and controls the charge / discharge thereof. The motor controller 12 controls the inverter INV1 to control the motor M1.
Adjust the rotation speed and output torque of the. The motor controller 13 controls the inverter INV2 to adjust the rotation speed and output torque of the motor M2. The motor controller 14 controls the inverter INV3 to adjust the rotation speed and output torque of the motor M3.

The motors M1 to M3 are three-phase AC motors such as induction machines and synchronous machines. Inverter INV1-I
The NV3 and the battery BAT are connected by the common DC link 17, and the electric power of the battery BAT is supplied to the motors M1 to M3 via the inverters INV1 to INV3 to generate the driving force from the motors M1 to M3, and the motor M1 and Generated power of M2 by inverter I
It is regenerated to the battery BAT via NV1 and INV2,
The battery BAT is charged while generating the braking force.
Of course, it is also possible to directly supply the electric power regenerated from the motor being regeneratively braked via the inverter to the motor being driven via the inverter without passing through the battery BAT.

The engine controller 15 performs throttle valve opening / closing control, fuel injection control, ignition timing control, etc. of the engine ENG (see FIG. 1) to start and stop the engine ENG and adjust the rotation speed and output torque. The brake controller 16 controls the brake actuator ACT (see FIG. 1) to control the ABS (Anti
-lock Brake System).

Here, the regenerative braking control when the battery BAT is in a fully charged state or a state close to a fully charged state will be described. The braking of the vehicle is basically realized by a mechanical braking method. That is, the brake fluid pressure generated by depressing the brake pedal 3 is applied to the booster BST.
To increase the pressure and drive the front brake FB and the rear brake RB. However, with such a mechanical braking method,
Since the energy possessed by the moving vehicle cannot be recovered, the mechanical braking method is assisted by an electric braking method called regenerative braking by the motor M2 to reduce the load of the mechanical braking method and the running energy of the vehicle. We will collect and effectively utilize the fuel to reduce overall fuel consumption.

However, when the battery BAT is in a fully charged state or a state close to a fully charged state, it is impossible to regenerate the running energy of the vehicle by the motor M2 to charge the battery BAT, and therefore, electric regenerative braking is applied. I can't. Therefore, when the battery BAT is in a fully charged state or a state close to a fully charged state, the engine E
While stopping NG, the electric power regenerated by the motor M2 is supplied to the motor M3, and the auxiliary equipment PSP, CMP, ATP is driven by the motor M3 instead of the engine ENG to consume the regenerative electric power and regenerative braking by the motor M2. To enable.

FIG. 3 is a flowchart showing an engine operation and stop control program according to one embodiment. The vehicle controller 10 is a main switch (not shown) of the vehicle.
When is set to the ON position, this control program is repeatedly executed.

In step 1, based on the state of charge SOC of the battery BAT detected by the battery controller 11, it is determined whether or not the battery BAT needs to be charged. SOC of battery BAT is 20-80
When the SOC of the battery BAT is less than 20% or more than 80%, it is determined that the battery does not need to be charged, and the process proceeds to step 6.

When the battery BAT needs to be charged,
In step 2, the engine controller 15 performs fuel injection control, ignition control, etc. to operate the engine ENG. Here, the engine operating state means the engine ENG
The fuel is supplied to the engine to ignite it, and the engine ENG is in a state of complete explosion. In step 3 after the engine is operated, the clutch CL is engaged, the motor M3 is rotated together with the rotation of the engine ENG, and the auxiliary machinery PSP, CMP, ATP are driven by the driving force of the engine ENG. Next, in step 4, the motor controller 12 is controlled to control the inverter INV1 and the motor M.
1 to generate power, and the generated power causes the battery BAT
To charge.

In step 5, the motor controller 14 controls the inverter INV3 to control the rotation speed of the motor M3. Specifically, the motor M
When the rotation speed of 3 is, for example, 3000 [rpm] or less, the inverter INV3 is stopped, and the motor M3 turns the engine ENG.
Just go around. On the other hand, when the rotation speed of the motor M3 exceeds 3000 [rpm], for example, the motor M3
The induced voltage becomes high, and a torque that cannot be ignored is generated. Therefore, when the rotation speed of the motor M3 exceeds 3000 [rpm], for example, the inverter INV3 is operated to keep the generated torque of the motor M3 at 0, while rotating the motor M3 in synchronization with the rotation of the engine ENG. To do. As a result, the motor M3 rotates at the same rotation speed as the rotation speed of the engine ENG, but no torque is generated. At this time, auxiliary machinery PSP, CMP, A
The TP is driven by the engine ENG.

When the rotation speed of the motor M3 (= rotation speed of the engine ENG) rises, the rotation speed of the motor M3 which shifts from the simple rotation state to the rotation speed control is:
It is not limited to the above-mentioned 3000 [rpm]. Further, the rotation speed control of the motor M3 described above may be performed over the entire speed range from low speed to high speed, instead of simply bringing the motor M3 into the accompanying state at low speed.

On the other hand, in step 1, the battery BA
When it is determined that the charging of T is unnecessary, it is determined in step 6 whether the motor drive mode is set. Here, when the current vehicle speed detected by the vehicle speed sensor 7 is equal to or lower than a predetermined vehicle speed (for example, 25 [km / h]), it is assumed that the driving mode is the driving force of the motor M2. Further, also when the shift sensor 8 detects the setting of the shift lever to the reverse R position, it is assumed that the traveling mode is the drive mode of the motor M2. It should be noted that when the battery BAT is in a charging required state or the current vehicle speed is a predetermined vehicle speed (for example, 25 [km /
h]) is exceeded, it is assumed that the drive mode is the drive mode of the engine ENG.

When it is determined that the battery BAT does not need to be charged and the motor drive mode is set, the process proceeds to step 7 and the engine controller 15 stops the engine ENG. Here, the engine stopped state is a state in which fuel supply to the engine ENG and ignition are stopped. In step 8, the clutch CL is disengaged to be in the disengaged state, and in the following step 9, the motor controller 14 controls the inverter INV3 to operate the motor M3 to drive the auxiliary machines RSP, CMP, ATP.

On the other hand, when it is determined that the battery BAT does not need to be charged and the motor drive mode is not set, the process proceeds to step 10 and the engine controller 1
5 supplies fuel to the engine ENG to ignite it, and operates the engine ENG. In step 11, the clutch CL is connected, and in step 12, the motor controller 1 is connected.
4 and the inverter INV3 perform the above-described rotation speed control of the motor M3. That is, the motor M3 is rotated at the same rotation speed as the engine rotation speed without generating torque. At this time, the auxiliary machines PSP, CMP, ATP are driven by the engine ENG.

FIG. 4 is a flowchart showing a regenerative braking control program for the motor according to the embodiment. The vehicle controller 10 repeatedly executes this control program when the main switch (not shown) of the vehicle is set to the ON position.

In step 21, it is determined whether the vehicle is braking. Here, when the accelerator sensor 5 detects the amount of depression of the accelerator pedal to be substantially zero, that is, the released state of the accelerator pedal is detected, and the brake sensor 6 detects the depressed state of the brake pedal 3, the vehicle is braking. And It should be noted that the method of determining whether or not the vehicle is braking is not limited to this embodiment, and it may be determined that the vehicle is braking only when, for example, the brake sensor 6 detects that the brake pedal 3 is stepped on. Alternatively, it may be determined that the vehicle is braking only when the accelerator sensor 5 detects the released state of the accelerator pedal.

When it is determined that the vehicle is braking, the routine proceeds to step 22, where it is determined whether or not charging is possible based on the state of charge SOC of the battery BAT detected by the battery controller 11. Here, the battery BAT
If the SOC of the battery exceeds 80%, the battery cannot be charged, but the reference SOC for determining whether the battery BAT can be charged is not limited to this embodiment. When the SOC of the battery BAT is less than 80% and can be charged, the routine proceeds to step 23, where the motor controller 13 and the inverter INV2 perform regenerative braking of the motor M2, and the battery BAT is charged with the regenerated electric power.

On the other hand, the SOC of the battery BAT is 80%
When it is determined that charging is not possible, the routine proceeds to step 24, where it is confirmed whether or not the engine ENG is in operation. As described above, the operating state of the engine refers to a state in which fuel is supplied to the engine ENG to ignite it and the engine ENG is completely exploded. When the engine ENG is in operation, in step 25, the engine controller 15 is controlled to stop fuel supply and ignition to the engine ENG, and stop the engine ENG.

Next, at step 26, the clutch CL is disengaged to bring the clutch into a disengaged state, and the process proceeds to step 27. Step 27
Then, the motor controller 13 and the inverter IN
The regenerative braking of the motor M2 is performed by V2, and regenerative electric power is supplied to the motor M3 through the inverter INV3, and the motor controller 14 and the inverter I
Operate the motor M3 by NV3 to drive auxiliary equipment PSP, C
Drives MP and ATP.

That is, since the battery BAT is in a fully charged state or a state close to a fully charged state, the regenerative electric power of the motor M2 is supplied to the motor M3, and the auxiliary machine is driven by the motor M3 instead of the engine ENG to regenerate the motor M2. It consumes power. At this time, when the regenerative power of the motor M2 is small and the auxiliary device cannot be driven by the motor M3 with only the regenerative power of the motor M2, the shortage of the regenerative power is automatically supplemented by the power of the battery BAT.

When it is determined that the vehicle is braking and the battery BAT cannot be charged, the engine ENG is stopped and the regenerative power from the motor M2 drives the motor M3 to drive the auxiliary equipment. Class PSP, CM
Since it is designed to drive P and ATP, the battery BA
Even when T is fully charged or close to fully charged, regenerative braking can be performed while making effective use of regenerative electric power, and the fuel consumption of a hybrid vehicle can be comprehensively reduced by stopping the engine during braking. You can

Correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is,
Engine ENG is the engine, motor M2 is the first motor, motor M3 is the second motor, battery B
AT is a battery, vehicle controller 10 is a braking determination means, chargeability determination means and control means, accelerator sensor 5 is an accelerator operation detection means, brake sensor 6 is a brake operation detection means, and battery controller 11 is an SOC detection means. Respectively.

In the above-described one embodiment, an example in which an AC motor is used for the motors M1 to M3 has been shown. For example, a DC motor is used for the motors M1 to M3, and DC-DC converters are used instead of the inverters INV1 to INV3. May be used.

[Brief description of drawings]

FIG. 1 is a diagram showing a mechanical configuration of an embodiment.

FIG. 2 is a diagram showing an electrical configuration of an embodiment.

FIG. 3 is a flowchart showing an engine operation / stop control program according to an embodiment.

FIG. 4 is a flowchart showing a regenerative braking control program for a motor according to an embodiment.

[Explanation of symbols]

ENG engine M1, M2, M3 motors AT automatic transmission FW front wheel RW rear wheel CL electromagnetic clutch PSP power steering oil pump CMP air conditioner / compressor ATP automatic transmission oil pump BST Booster (Booster) ACT brake actuator FB front brake RB rear brake BAT battery INV1, INV2, INV3 inverter 1, 2 pulley and belt mechanism 3 brake pedal 4a, 4b Brake fluid piping 5 Accelerator sensor 6 Brake sensor 7 vehicle speed sensor 8 shift sensor 10 Vehicle controller 11 Battery controller 12-14 Motor controller 15 engine controller 16 Brake controller 17 Common DC link

Continued front page    F term (reference) 3G093 AA07 BA19 BA22 CB07 DA06                       DB05 DB11 DB15 EB09 EC02                       FA12 FB05                 5H115 PA11 PG04 PI16 PI22 PI29                       PI30 PO01 PO06 PU01 PU28                       PV09 QA01 QE10 QI04 QN02                       QN04 RE02 SE01 SE06 SF01                       SJ11 TB01 TE02 TI01 TO21                       TR19 TU16

Claims (3)

[Claims] 1. An engine for driving a vehicle to drive an on-vehicle accessory, a first motor for driving and braking a vehicle, and a second motor for driving an on-vehicle accessory when the engine is stopped. A motor driving means for supplying electric power of a battery to the first motor and the second motor to drive the motor and charging the battery with electric power regenerated from the first motor during braking, and whether the vehicle is being braked. When the vehicle is being braked, and when it is determined that the battery is not chargeable, the engine is turned on. Along with stopping
A regenerative braking device for a hybrid vehicle, comprising: a control unit that drives the second motor with regenerative electric power from the first motor to drive an in-vehicle accessory. 2. The regenerative braking system for a hybrid vehicle according to claim 1, wherein the braking determination means is an accelerator operation detecting means for detecting a released state of an accelerator pedal, and a brake operation is for detecting a depressed state of a brake pedal. A regenerative braking device for a hybrid vehicle, comprising: a detection means, wherein when the release state of the accelerator pedal is detected and the depression state of the brake pedal is detected, it is determined that braking is being performed. 3. The regenerative braking system for a hybrid vehicle according to claim 1, wherein the charging possibility determining means is a charging state S of the battery.
A regenerative braking device for a hybrid vehicle, comprising SOC detection means for detecting OC (State Of Charge), and determining whether or not charging is possible based on the detected SOC.