JP2008133940A - Automatic transmission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock-up clutch control device for reducing dragging by setting lock-up clutch releasing pressure to be higher for a predetermined time when detecting a change of an engine revolution speed in a state that an oil temperature reaches a predetermined value or lower at stopping a vehicle. <P>SOLUTION: The vehicle lock-up clutch control device is used in a fluid transmission device for an automatic transmission. The device comprises (a) an oil temperature determining means for determining that an operating oil temperature reaches a predetermined value or lower, (b) a revolution change determining means for determining a change of engine revolution, and (c) a setting means for setting lock-up clutch releasing pressure to be higher than static pressure when the oil temperature reaches the predetermined value or lower and the change of engine revolution is detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a lockup clutch for a vehicle provided in a fluid transmission device, and more particularly to a technique for preventing dragging by controlling a release pressure of the lockup clutch.

  A vehicle having a fluid transmission device with a lock-up clutch between, for example, an engine and an automatic transmission, and transmitting the output torque of the engine to the input shaft of the automatic transmission through the fluid transmission device with the lock-up clutch. Are known. In this fluid transmission device, power is transmitted through fluid such as hydraulic oil between a pump impeller connected to an engine and a turbine impeller connected to an input shaft of an automatic transmission. It is known as a coupling or torque converter. In vehicles equipped with such a fluid transmission device with a lock-up clutch, various lock-up clutch control devices have been proposed in order to stably perform slip control of the lock-up clutch.

  With respect to such a lockup clutch, it is necessary to cut off the power transmission between the engine and the automatic transmission when the vehicle is stopped. Therefore, the release side hydraulic pressure in the lockup clutch is made higher than the engagement side hydraulic pressure. The lockup clutch is released by setting the differential pressure between the combined hydraulic pressure and the releasing hydraulic pressure to be negative.

  On the other hand, when the lockup clutch is released, there is a rotational speed difference between the rotational speed of the front cover to which the lockup clutch is engaged and the rotational speed of the lockup piston. A phenomenon in which torque is generated due to friction of the working oil that is the working fluid, that is, dragging may occur. Such drag is desired to be minimized because it leads to loss of fuel consumption.

In order to suppress such drag, a technique for increasing the line pressure has been proposed. That is, since the lockup release pressure of the lockup clutch is a so-called secondary pressure that depends on the line pressure, the lockup release pressure is increased by increasing the line pressure. As a result, the pressure difference between the oil pressure in the engagement side oil chamber and the oil pressure in the release side oil chamber of the lockup clutch is kept high, and the lockup clutch is fully released, that is, the lockup piston and the This is because the front cover can be sufficiently separated and dragging is prevented. In particular, Patent Document 1 proposes a technique for setting the release pressure of the lockup clutch to a high level for a predetermined time after the vehicle stops in order to prevent dragging of the lockup clutch when the vehicle is stopped.
JP-A-2005-121121

  By the way, when the temperature is low, the viscosity of the working oil, which is the working fluid of the lockup clutch, is high, so that the outflow of the working oil from the engagement side oil chamber of the lockup clutch is reduced. As a result, the oil pressure in the engagement side oil chamber of the lockup clutch becomes high, so the difference in pressure between the oil pressure in the engagement side oil chamber and the oil pressure in the release side oil chamber becomes small, and the lockup clutch is fully released. Otherwise, dragging by the lock-up clutch may occur.

  However, since the technique described in Patent Document 1 sets the release pressure of the lockup clutch to a high pressure for a predetermined time after the vehicle stops, the technique disclosed in Patent Document 1 against the occurrence of dragging at such a low temperature. Depending on the technology described, it is not possible to cope with it suitably.

  Also, if the line pressure is constantly increased at a low temperature to suppress the drag, the amount of oil sucked from the strainer increases and the oil level in the oil pan decreases, making it easier to suck air and make noise. There was a possibility that it would occur or the line pressure would drop.

  The present invention has been made against the background of the above circumstances, and its purpose is to lock up when a change in engine speed is detected when the oil temperature is below a predetermined value when the vehicle is stopped. An object of the present invention is to provide a lockup clutch control device that sets the clutch release pressure to a high pressure for a predetermined time.

  In order to achieve this object, the invention according to claim 1 is a control device for a lockup clutch for a vehicle provided in a fluid transmission device for transmitting the output of an engine to an automatic transmission. Oil temperature determining means for determining that the oil temperature is not more than a predetermined value; (b) rotation fluctuation determining means for determining rotation fluctuation of the engine; and (c) a low oil temperature at which the oil temperature is not more than the predetermined value And setting means for setting a lock-up clutch release pressure for releasing the lock-up clutch higher than a steady pressure when an engine rotation fluctuation is detected.

  In this case, when the oil temperature determining means determines that the hydraulic oil temperature is equal to or lower than a predetermined value, and the engine speed fluctuation determination is determined by the engine speed fluctuation determining means, the lockup is performed by the setting means. The lock-up clutch release pressure for releasing the clutch is set higher than the value of the release pressure of the lock-up clutch that is set when the steady pressure, that is, the hydraulic oil temperature is higher than the predetermined value. The release pressure of the lock-up clutch is controlled to suitably prevent the lock-up clutch from being dragged when a change in engine speed that is less than a predetermined value and fluctuates with the drag of the lock-up clutch is detected. Can do.

  Preferably, the setting means returns the release pressure of the lockup clutch to a steady pressure when a predetermined end condition is satisfied. In this way, when the end condition is satisfied, the release pressure of the lockup clutch is returned to the steady pressure. Therefore, compared to the case where the release pressure is constantly set high at a low oil temperature, the pressure from the strainer is reduced. Air suction due to an increase in the amount of sucked oil can be suppressed.

  Preferably, the termination condition is (d) an engine provided in the vehicle is not in an idle state, (e) a rotational speed of a turbine of the fluid transmission device is a predetermined value or more, (f) The engine rotational speed is greater than or equal to a predetermined value, (g) a predetermined time has elapsed since the start of operation of the setting means, or (h) the automatic transmission is in the N range. It is that. In this way, when any of the end conditions is satisfied, the release pressure of the lockup clutch is returned to the steady pressure by the setting means, so that the release pressure is constantly set high at a low oil temperature. Compared with the case, it is possible to suppress air suction due to an increase in the amount of oil sucked from the strainer.

  In this specification, “supplying hydraulic pressure” means “applying hydraulic pressure” or “supplying hydraulic oil controlled to the hydraulic pressure”.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a skeleton diagram illustrating the configuration of a vehicular automatic transmission (hereinafter referred to as an automatic transmission) 10 to which the present invention is applied. FIG. 2 is an operation chart (engagement operation table) for explaining combinations of operations of engagement devices (engagement elements) when a plurality of gear stages (shift stages) of the automatic transmission 10 are established. This automatic transmission 10 includes a first transmission unit 14 mainly composed of a double pinion type first planetary gear unit 12 and a single pinion type in a transmission case 32 as a non-rotating member attached to a vehicle body. The second planetary gear unit 16 and the second transmission unit 20 mainly composed of the double pinion type third planetary gear unit 18 are provided on a common axis C, and the rotation of the input shaft 22 is shifted and output. Output from the shaft 24. The input shaft 22 corresponds to an input rotation member. In this embodiment, the input shaft 22 is a fluid transmission device provided in the automatic transmission 10 between the engine 26 that is a driving power source and the first transmission unit 14. This is the turbine shaft of the torque converter 28. The output shaft 24 corresponds to an output rotating member, and rotationally drives the left and right drive wheels sequentially through, for example, a differential gear device (final reduction gear) (not shown) and a pair of axles. The torque converter 28 is rotationally driven by the engine 26 to transmit the power of the engine 26 to the input shaft 22 via the fluid, and to directly transmit the power of the engine 26 to the input shaft 22 without passing the fluid. As a lock-up clutch 30. The automatic transmission 10 is configured substantially symmetrically with respect to the center line (axial center) C, and the lower half of the axial center C is omitted in the skeleton diagram of FIG.

  The first planetary gear unit 12 includes a sun gear S1, a plurality of pairs of pinion gears P1 that mesh with each other, a carrier CA1 that supports the pinion gears P1 so as to rotate and revolve, and a ring gear R1 that meshes with the sun gears S1 via the pinion gears P1, sun gears S1, Three rotating elements are constituted by the carrier CA1 and the ring gear R1. The carrier CA1 is connected to the input shaft 22 and is driven to rotate. The sun gear S1 is fixed to the transmission case 32 so as not to rotate. The ring gear R <b> 1 functions as an intermediate output member, is rotated at a reduced speed with respect to the input shaft 22, and transmits the rotation to the second transmission unit 20. In the present embodiment, the path for transmitting the rotation of the input shaft 22 to the second transmission unit 20 at the same speed is the first intermediate output path for transmitting the rotation at a predetermined constant gear ratio (= 1.0). The first intermediate output path PA1 includes a first path PA1a that transmits rotation from the input shaft 22 to the second transmission unit 20 without passing through the first planetary gear unit 12, and a first planet from the input shaft 22. There is a second path PA1b that transmits the rotation to the second transmission unit 20 via the carrier CA1 of the gear device 12. Further, the transmission ratio from the input shaft 22 to the second transmission unit 20 via the carrier CA1, the pinion gear P1 disposed on the carrier CA1, and the ring gear R1 is larger than the first intermediate output path PA1 (> 1). .0) is a second intermediate output path PA2 that transmits the rotation of the input shaft 22 with a reduced speed (deceleration).

  The second planetary gear device 16 includes a sun gear S2, a pinion gear P2, a carrier CA2 that supports the pinion gear P2 so as to rotate and revolve, and a ring gear R2 that meshes with the sun gear S2 via the pinion gear P2. The third planetary gear unit 18 meshes with the sun gear S3 via the sun gear S3, a plurality of pairs of pinion gears P2 and P3 that mesh with each other, a carrier CA3 that supports the pinion gears P2 and P3 so that they can rotate and revolve, and pinion gears P2 and P3. A ring gear R3 is provided.

  In the second planetary gear device 16 and the third planetary gear device 18, four rotating elements RM <b> 1 to RM <b> 4 are configured by being partially connected to each other. Specifically, the first rotating element RM1 is configured by the sun gear S2 of the second planetary gear unit 16, and the carrier CA2 of the second planetary gear unit 16 and the carrier CA3 of the third planetary gear unit 16 are integrally connected to each other. The second rotating element RM2 is configured, and the ring gear R2 of the second planetary gear unit 16 and the ring gear R3 of the third planetary gear unit 18 are integrally connected to each other to configure the third rotating element RM3, and the third planetary gear unit. The 18th sun gear S3 constitutes a fourth rotating element RM4. In the second planetary gear device 16 and the third planetary gear device 18, the carriers CA2 and CA3 are configured by a common member, the ring gears R2 and R3 are configured by a common member, and the second planetary gear device 18 The pinion gear P <b> 2 of the planetary gear device 16 is a Ravigneaux type planetary gear train that also serves as the second pinion gear of the third planetary gear device 18.

  The first rotating element RM1 (sun gear S2) is selectively connected to the transmission case 32 via the first brake B1 and stopped rotating, and the first planetary gear unit 12 which is an intermediate output member via the third clutch C3. Ring gear R1 (that is, second intermediate output path PA2) is selectively connected to the carrier CA1 of the first planetary gear device 12 via the fourth clutch C4 (that is, second path PA1b of the first intermediate output path PA1). Is selectively linked to The second rotation element RM2 (carriers CA2 and CA3) is selectively connected to the transmission case 32 via the second brake B2 and stopped, and the input shaft 22 (that is, the first shaft 22) (ie, the first clutch C2). It is selectively connected to the first path PA1a) of the intermediate output path PA1. The third rotation element RM3 (ring gears R2 and R3) is integrally connected to the output shaft 24 to output rotation. The fourth rotation element RM4 (sun gear S3) is connected to the ring gear R1 via the first clutch C1. Between the second rotating element RM2 and the transmission case 32, there is a second one-way clutch F1 that prevents the reverse rotation while allowing the second rotating element RM2 to rotate forward (the same rotational direction as the input shaft 22). It is provided in parallel with the brake B2.

  The engagement operation table of FIG. 2 is a table for explaining the operation states of the clutches C1 to C4 and the brakes B1 and B2 when each gear stage of the automatic transmission 10 is established, and “◯” indicates the engagement state, “(◯)” represents the engaged state only during engine braking, and the blank represents the released state. As described above, the automatic transmission 10 includes three sets of planetary gear devices 12, 16, and 18, and a plurality of gears having different gear ratios by selectively engaging the clutches C1 to C4 and the brakes B1 and B2. A multi-stage shift of eight stages, for example, eight forward stages, is achieved. In particular, since the one-way clutch F1 is provided in parallel with the second brake B2, when the first gear (1st) is established, the second brake B2 is engaged during engine braking, while during driving. Be released.

  The gear ratios that differ for each gear stage are appropriately determined by the gear ratios ρ1, ρ2, and ρ3 of the first planetary gear device 12, the second planetary gear device 16, and the third planetary gear device 18. The clutches C1 to C4 and the brakes B1 and B2 (hereinafter simply referred to as the clutch C and the brake B unless otherwise distinguished) are hydraulic friction members that are controlled by a hydraulic actuator such as a multi-plate clutch or a brake. A joint device (hereinafter referred to as an engagement device).

  FIG. 3 is a circuit diagram relating to the linear solenoid valves SL1 to SL5 and SLU for controlling the operation of the hydraulic actuators of the clutch C and the brake B and the lockup clutch 30, and a hydraulic control circuit constituting a part of the hydraulic control device. FIG.

  In FIG. 3, D range pressures (forward range pressure, forward hydraulic pressure) PD output from the hydraulic pressure supply device 46 are respectively applied to the hydraulic actuators (hydraulic cylinders) 34, 36, 42 of the clutches C1, C2 and the brake B1. The pressure is regulated and directly supplied by the linear solenoid valves SL1, SL2, and SL5, and the line hydraulic pressure PL1 output from the hydraulic pressure supply device 46 is supplied to the hydraulic actuators 38 and 40 of the clutches C3 and C4, respectively. The pressure is adjusted by SL4 and supplied directly.

  Further, the D range pressure PD or the reverse pressure (reverse hydraulic pressure) PR output from the hydraulic pressure supply device 46 is supplied to the hydraulic actuator 44 of the second brake B2 via the second brake control circuit 90. Yes. The second brake control circuit 90 is supplied with the control pressure PSLU, which is the output hydraulic pressure of the linear solenoid valve SLU, using the modulator hydraulic pressure PM output from the hydraulic pressure supply device 46 as a source pressure, via the switching circuit 100. It has become. Further, when the control pressure PSLU supplied to the second brake control circuit 90 via the switching circuit 100 becomes equal to or higher than a predetermined pressure for generating the engagement torque of the second brake B2, a predetermined signal, for example, an ON signal SWON Is provided on the input side of the second brake control circuit 90. The hydraulic switch 48 is provided to the electronic control device 160 (see FIG. 5).

  The hydraulic pressure supply device 46 adjusts the line hydraulic pressure PL1 (first line hydraulic pressure PL1) using the hydraulic pressure generated from a mechanical oil pump 52 (see FIG. 1) rotated and driven by the engine 26 as a primary pressure. Secondary regulator for regulating the line oil pressure PL2 (second line oil pressure PL2, secondary pressure PL2) using the oil pressure discharged from the regulator valve 82 as a source pressure for regulating the line oil pressure PL1 by the regulator valve 82). A linear solenoid valve SLT that supplies a signal pressure PSLT to the first pressure regulating valve 82 and the second pressure regulating valve 84 in order to regulate the pressure to a valve (second pressure regulating valve) 84, line oil pressure PL1, PL2 corresponding to the engine load, etc. Modulation of modulator oil pressure PM to a constant value using line oil pressure PL1 as the original pressure The shift lever 72 receives the line hydraulic pressure PL1 that has been mechanically actuated in accordance with the operation of the regulator valve 86 and the shift lever 72 that is mechanically connected via a cable, a link, or the like, and the oil passage is switched. A manual valve 88 that outputs as a D range pressure PD when operated to the “D” position or “S” position or as a reverse pressure PR when operated to the “R” position is provided. The modulator hydraulic pressure PM, the D range pressure PD, and the reverse pressure PR are supplied.

  The linear solenoid valves SL1 to SL5 and SLU have basically the same configuration, and are excited and de-energized independently by the electronic control unit 160, and the hydraulic pressures of the hydraulic actuators 34 to 44 are independently regulated and controlled. The engagement pressures of C1 to C4 and brakes B1 and B2 are controlled. In the automatic transmission 10, for example, as shown in the engagement operation table of FIG. 2, each gear stage is established by engaging a predetermined engagement device. In the shift control of the automatic transmission 10, for example, a so-called clutch-to-clutch shift is performed in which release and engagement of the clutch C and the brake B involved in the shift are controlled simultaneously. For example, as shown in the engagement operation table of FIG. 2, in the downshift from the fifth speed to the fourth speed, the clutch C2 is disengaged and the clutch C4 is engaged, so that the release transient hydraulic pressure of the clutch C2 is suppressed so as to suppress the shift shock. And the engagement transient hydraulic pressure of the clutch C4 are appropriately controlled. Thus, since the engagement devices (clutch C, brake B) of the automatic transmission 10 are respectively controlled by the linear solenoid valves SL1 to SL5, SLU, the responsiveness of the operation of the engagement device is improved. Alternatively, the hydraulic circuit for the engagement / release operation of the engagement device is simplified.

  Further, the linear solenoid valve SLU is configured so that the engagement pressure of the second brake B2 serving as a predetermined hydraulic friction engagement device of the clutch C and the brake B and the torque of the lockup clutch 30 are switched by the oil path switching by the switching circuit 100. This is a single (shared) solenoid valve that selectively controls the capacity. The second brake B2 is a hydraulic friction engagement device that is engaged only at the time of engine braking. For example, the lockup clutch 30 is set so that engine stall does not occur during engine braking (particularly during engine braking during low-speed traveling). Since the lockup is not turned on, it is not necessary to control the engagement pressure of the second brake B2 and the engagement state and the release state of the lockup clutch 30 at the same time. A valve can be used.

  FIG. 4 includes a schematic diagram of the switching circuit 100 and is a diagram for explaining the switching between the engaged state and the released state of the lockup clutch 30 by the linear solenoid valve SLU switched by the switching circuit 100.

  In FIG. 4, the lock-up clutch 30 is supplied via the oil pressure PON in the engagement side oil chamber 104 supplied via the engagement oil passage 102 and the release oil passage 106 as is well known. This is a hydraulic friction clutch that is frictionally engaged with the front cover 110 by a differential pressure ΔP (= PON−POFF) with respect to the hydraulic pressure POFF in the release side oil chamber 108. The operating condition of the torque converter 28 is, for example, a so-called lockup-off in which the differential pressure ΔP is negative and the lockup clutch 30 is released, and the differential pressure ΔP is zero or more and the lockup clutch 30 is half-engaged. The so-called slip state, and the so-called lock-up on, in which the lock-up clutch 30 is completely engaged by setting the differential pressure ΔP to the maximum value, are roughly classified. Further, in the slip state of the lock-up clutch 30, since the differential pressure ΔP is set to zero, the torque sharing of the lock-up clutch 30 is eliminated, and the torque converter 28 is set to the operating condition equivalent to the lock-up off.

  The switching circuit 100 includes a lockup relay valve 112 for switching the lockup clutch 30 between a disengaged state, that is, a lockup off state, and a slip state including a disengaged state, that is, a disengaged state or a lockup on state. A lock-up control valve that adjusts the differential pressure ΔP when the lock-up clutch 30 is in the engaged state by 112 and switches the operating state of the lock-up clutch 30 from the slip state including the released state to the lock-up on range. 114.

  The lock-up relay valve 112 includes a spool valve element 116, a spring 118 that is provided on one shaft end side of the spool valve element 116 and applies a thrust toward the release (OFF) side position of the spool valve element 116, a spool valve Position for engaging (ON) the spool valve element 116 provided on the other shaft end side of the spool valve element 116 and the oil chamber 120 that receives the reverse pressure PR to urge the element 116 to the OFF position. And an oil chamber 122 that receives a control pressure PSL that is an output hydraulic pressure of the ON-OFF solenoid valve SL that uses the modulator hydraulic pressure PM as a source pressure. This ON-OFF solenoid valve SL is excited and de-energized by the electronic control device 160, and functions as a control pressure generating valve that switches the engagement and release states of the lockup clutch 30.

  The lock-up control valve 114 includes a spool valve element 124, a spring 126 that applies a thrust F126 that moves the spool valve element 124 toward a slip (SLIP) side position, and urges the spool valve element 124 toward a SLIP side position. For this purpose, the oil chamber 128 that receives the hydraulic pressure PON in the engagement side oil chamber 104 of the torque converter 28 and the torque converter 28 for biasing the spool valve element 124 toward the fully engaged (ON) side position. An oil chamber 130 that receives the hydraulic pressure POFF in the release-side oil chamber 108 and an oil chamber 132 that receives the control pressure PSLU to urge the spool valve element 124 toward the ON side position are provided.

  The switching circuit 100 configured in this manner switches the operating oil pressure supply state to the engagement side oil chamber 104 and the release side oil chamber 108 and switches the operation state of the lockup clutch 30.

  First, the case where the lockup clutch 30 is set to lockup off will be described. In the lockup relay valve 112, when the control pressure PSL is not supplied to the oil chamber 122 and the spool valve element 116 is urged to the release (OFF) side position by the thrust of the spring 118, the line pressure supplied to the input port 134 is supplied. PL2 is supplied from the release side port 136 through the release oil passage 106 to the release side oil chamber 108. Then, the hydraulic oil discharged to the engagement side port 138 through the engagement oil passage 102 through the engagement side oil chamber 104 is discharged from the discharge port 140 to an oil cooler (COOLER) or a cooler bypass (COOLER BY-PASS). The As a result, the lockup clutch 30 is turned off. At this time, since the hydraulic pressure in the release side oil chamber 108 becomes higher than the hydraulic pressure in the engagement side oil chamber 104, the differential pressure ΔP becomes negative.

  Next, the case where the lockup clutch 30 is set to the slip state including the released state or the lockup on will be described. In the lockup relay valve 112, when the control pressure PSL is supplied to the oil chamber 122 and the spool valve element 116 is biased to the engagement (ON) side position, the line pressure PL2 supplied to the input port 134 is engaged. The oil is supplied from the side port 138 through the engagement oil passage 102 to the engagement side oil chamber 104. The line pressure PL2 supplied to the engagement side oil chamber 104 becomes the hydraulic pressure PON. At the same time, the release side oil chamber 108 is communicated with the control port 148 of the lockup control valve 114 from the release side port 136 through the bypass port 146 through the release oil passage 106. Then, the hydraulic pressure POFF in the release side oil chamber 108 is adjusted by the lockup control valve 114, that is, the differential pressure ΔP is adjusted by the lockup control valve 114, and the operating state of the lockup clutch 30 is changed from the slip state to the lockup. It can be switched in the ON range.

  Specifically, when the spool valve element 116 of the lockup relay valve 112 is biased to the engagement side position, that is, when the lockup clutch 30 is switched to the engagement side state, the lockup control valve In 114, the control pressure PSLU for urging the spool valve element 124 to the fully engaged (ON) side position is not supplied to the oil chamber 132, and the spool valve element 124 slips (SLIP) by the thrust F 126 of the spring 126. In the side position, the line pressure PL2 supplied to the input port 150 is supplied from the control port 148 via the bypass port 146 to the release side oil chamber 108 from the release side port 136 through the release oil passage 106. In this state, the differential pressure ΔP is controlled by the control pressure PSLU, and the slip state (including the released state) of the lockup clutch 30 is controlled.

  Further, when the spool valve element 116 of the lockup relay valve 112 is urged to the engagement side position, the spool valve element 124 is urged to the complete engagement (ON) side position in the lockup control valve 114. When the control pressure PSLU is supplied to the oil chamber 132, the line pressure PL2 is not supplied from the input port 150 to the release side oil chamber 108, and the discharge of hydraulic oil from the release side oil chamber 108 is controlled to the control port 148. It is shut off at. As a result, since the hydraulic pressure POFF is set to zero, the differential pressure ΔP is maximized, and the lockup clutch 30 is completely engaged.

  Thus, the lockup relay valve 112 is a first oil passage (hereinafter referred to as a first oil passage) for releasing the lockup clutch 30 in accordance with the control pressure PSLU that is the output hydraulic pressure of the linear solenoid valve SLU. ) That is, a second oil passage (hereinafter referred to as a second oil passage) for controlling the torque capacity by bringing the lock-up clutch 30 into an engaged state or a semi-engaged state according to the release side position and the control pressure PSLU. That is, it is a relay valve that switches the engagement side position.

  FIG. 5 is a block diagram illustrating a main part of a control system provided in the vehicle for controlling the automatic transmission 10 of FIG. The electronic control unit 160 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the process, output control of the engine 26, shift control of the automatic transmission 10, torque capacity control of the lockup clutch 30, and the like are executed, and for engine control and automatic transmission 10 as required. And for hydraulic control of the lock-up clutch 30.

  In FIG. 5, an accelerator operation amount sensor 56 for detecting the operation amount Acc of the accelerator pedal 54, an engine rotation speed sensor 58 for detecting the rotation speed NE of the engine 26, and an intake air amount Q of the engine 26 are detected. Intake air amount sensor 60, intake air temperature sensor 62 for detecting intake air temperature TA, throttle valve opening sensor 64 for detecting electronic throttle valve opening θTH, vehicle speed V (rotation of output shaft 24) A vehicle speed sensor 66 for detecting the speed NOUT), a cooling water temperature sensor 68 for detecting the cooling water temperature TW of the engine 26, a brake switch 70 for detecting whether or not a foot brake as a service brake is operated, and a shift. Lever position for detecting at which lever position (operation position) PSH the lever 72 is located Sensor 74, turbine rotational speed sensor 76 for detecting turbine rotational speed NT (= rotational speed NIN of input shaft 22), and AT oil temperature TOIL which is the temperature of the hydraulic oil in hydraulic control circuit 50 An AT oil temperature sensor 78, an acceleration sensor 80 for detecting the acceleration (deceleration) G of the vehicle, and the like are provided. The accelerator operation amount Acc, the engine speed NE, the intake air amount are provided from these sensors and switches. Q, intake air temperature TA, throttle valve opening θTH, vehicle speed V, output shaft rotational speed NOUT, engine coolant temperature TW, presence / absence of brake operation, lever position PSH of shift lever 72, turbine rotational speed NT (= input shaft rotational speed) NIN), AT oil temperature TOIL, vehicle acceleration (deceleration) G, ON signal SWON from hydraulic switch 48, etc. A signal is supplied to the electronic control unit 160.

  Although not shown in the figure, an idle speed control (ISC) valve 190 is provided in parallel with the electronic throttle valve in the intake pipe that performs intake to the engine 26. The ISC valve 190 adjusts the intake air amount by the ISC valve 190 so that the rotational speed NE of the engine 26 becomes the idle engine rotational speed set in the electronic control device 160 when the electronic throttle valve 56 is in the fully closed state. . Further, the ISC valve 190 is provided with an ISC valve opening sensor 192 for detecting the opening θISC of the ISC valve 190. The opening θISC of the ISC valve 190 is changed from the ISC valve opening sensor 192 to the electronic control device 160. To be supplied.

  Also, the linear solenoid valves SL1 to SL5 and the SLU excitation / de-energization, current control signal, lock-up for controlling the switching of the engagement / release state of the clutch C and the brake B and the transient hydraulic pressure at the engagement / release. The ON / OFF solenoid valve SL excitation / de-energization signal for switching the oil path of the relay valve 112, the torque capacity of the lockup clutch 30 such as the current control signal of the linear solenoid valve SLU for controlling the differential pressure ΔP, etc. Supplied from the control device 160.

  The shift lever 72 is disposed in the vicinity of the driver's seat, for example, and is manually operated to five lever positions “P”, “R”, “N”, “D”, or “S” as shown in FIG. It is like that.

  The “P” position (range) releases the power transmission path in the automatic transmission 10, that is, a neutral state (neutral state) in which the power transmission in the automatic transmission 10 is interrupted, and is mechanically output by the mechanical parking mechanism. This is a parking position (position) for preventing (locking) the rotation of 24, and the “R” position is a reverse travel position (position) for making the rotation direction of the output shaft 24 of the automatic transmission 10 reverse. , “N” position is a neutral position (position) for neutralizing power transmission in the automatic transmission 10, and “D” position is the first to eighth speeds of the automatic transmission 10. The automatic shift mode is established in the shift range (D range) that allows the shift, and all the forward gears from the first gear stage “1st” to the eighth gear stage “8th” are used. The forward travel position (position) for executing the shift control, and the “S” position is the forward travel capable of manual shift by switching a plurality of shift ranges having different gear speeds on the high-speed side or a plurality of different gear stages. Position.

  In this “S” position, the shift range or gear stage is shifted to the up side every time the shift lever 72 is operated, and the shift range or gear stage is shifted to the down side every time the shift lever 72 is operated. A “-” position is provided for this purpose. For example, in the “S” position, any of the “D” range, “7” range,..., “2” range, “L” range is the “+” position or “−” position of the shift lever 72. Changed according to the operation. The “L” range in the “S” position is also an engine brake range for obtaining a further engine brake effect by engaging the second brake B2 at the first gear stage “1st”.

  In each of the shift positions indicated by the “P” to “S” positions, the “P” position and the “N” position are power transmission cut-off positions that disable driving of the vehicle in which the power transmission path in the automatic transmission 10 is cut off. (Position), which is a non-traveling position (position) that is selected when the vehicle is not traveling. The “R” position, the “D” position, and the “S” position are power transmission possible positions (positions) that enable driving of the vehicle to which the power transmission path in the automatic transmission 10 is connected. This is the travel position selected when traveling.

  Thus, the shift lever 72 is an operating device that can be switched between a traveling position for switching the automatic transmission 10 to a power transmission enabled state and a non-traveling position for switching the automatic transmission 10 to a power transmission interrupted state. .

  FIG. 7 is a functional block diagram for explaining a main part of the control function by the electronic control unit 160. In FIG. 7, the shift control means 162 changes the actual vehicle speed V and the accelerator operation amount Acc from the relationship (map, shift diagram) stored in advance with the vehicle speed V and the accelerator operation amount Acc as parameters, for example, as shown in FIG. Based on the shift determination, it is determined whether or not the shift of the automatic transmission 10 should be executed. For example, the shift stage of the automatic transmission 10 to be shifted is determined, and the automatic shift is performed so that the determined shift stage is obtained. The automatic shift control of the machine 10 is executed. At this time, the shift control means 162 engages and / or releases the hydraulic friction engagement device involved in the shift of the automatic transmission 10 so that the shift stage is achieved according to, for example, the engagement table shown in FIG. A command (shift output command, hydraulic command) is output to the hydraulic control circuit 50.

  The hydraulic control circuit 50 operates the linear solenoid valves SL1 to SL5 and SLU in the hydraulic control circuit 50 so that the shift of the automatic transmission 10 is executed in accordance with the command, and the hydraulic friction mechanism involved in the shift. Actuate the hydraulic actuator of the combined device.

  In the shift diagram of FIG. 8, a solid line is a shift line for determining an upshift (upshift line), and a broken line is a shift line for determining a downshift (downshift line). Further, the shift line in the shift diagram of FIG. 8 indicates whether or not the actual vehicle speed V crosses the line on the horizontal line indicating the actual accelerator operation amount Acc (%), that is, the value on which the shift on the shift line is to be executed ( This is for determining whether or not the shift point vehicle speed) VS has been exceeded, and is also stored in advance as a series of this value VS, that is, the shift point vehicle speed. Note that the shift line diagram of FIG. 8 illustrates the shift lines in the first gear stage to the sixth gear stage among the first gear stage to the eighth gear stage in which a shift is executed by the automatic transmission 10.

  For example, if the shift control means 162 determines that the actual vehicle speed V has crossed the 7th speed → 8th speed upshift line at which the 7th speed → 8th speed upshift should be executed, that is, the speed change point vehicle speed V7-8 is exceeded. If it is determined that the clutch C3 has been released, a command to release the clutch C3 and to engage the brake B1 is output to the hydraulic control circuit 50, that is, a command to drain (drain) the engagement hydraulic pressure of the clutch C3 by de-excitation. While outputting to valve SL3, the command which supplies the engagement hydraulic pressure of brake B1 by excitation is output to linear solenoid valve SL5.

  In this way, the shift control means 162 controls the excitation and de-excitation of the linear solenoid valves SL1 to SL5 and SLU, respectively, thereby causing the clutches C1 to C4 and the brake B1 corresponding to the linear solenoid valves SL1 to SL5 and SLU, respectively. , B2 is functionally provided with an engagement capacity control means 164 for switching the engagement / release state of B2 to establish one of the first gear stage “1st” to the eighth gear stage “8th”.

  Further, when the engagement capacity control means 164 controls the engagement pressure of the second brake B2 by the linear solenoid valve SLU in order to obtain the engine brake action in the “L” range, the lockup relay valve 112 is the first. It needs to be switched to the oil passage. Therefore, the shift control means 162 does not output the control pressure PSL by the ON-OFF solenoid valve SL so that the control pressure PSLU is supplied to the second brake B2 when the engine brake is required, and the lockup relay valve 112 is operated. A relay valve control means 166 for switching to the first oil passage side is functionally provided.

  Further, when the electronic control device 160 controls the differential pressure ΔP by the control pressure PSLU so that the torque capacity of the lockup clutch 30 can be controlled, the lockup relay valve 112 needs to be switched to the second oil passage. . Therefore, the relay valve control means 166 switches the lockup relay valve 112 to the second oil passage side by outputting the control pressure PSL by the ON-OFF solenoid valve SL so that the differential pressure ΔP is controlled by the linear solenoid valve SLU. .

  For example, the electronic control device 160 has a release (lock-up off) region, a slip control region, and an engagement (lock-up on) region in two-dimensional coordinates having the throttle valve opening θTH and the vehicle speed V as parameters as shown in FIG. Lock-up clutch control for controlling switching of the operating state of the lock-up clutch 30 based on the actual vehicle running state, for example, the throttle valve opening θTH and the vehicle speed V, based on the previously stored relationship (map, lock-up region diagram) Means are provided functionally.

  For example, the electronic control device 160 outputs a control command for the ON-OFF solenoid valve SL to the hydraulic control circuit 50 for switching the lockup clutch 30 to lockup off or switching to slip or lockup on, A control command for the linear solenoid valve SLU is output to the hydraulic control circuit 50 for controlling the differential pressure ΔP.

  As described above, the linear solenoid valve SLU of the present embodiment controls the engagement pressure of the second brake B2 when the engine brake is necessary by switching the oil passage by the lockup relay valve 112, and the lockup clutch 30 This is a single solenoid valve that controls the torque capacity (differential pressure ΔP) of the lockup clutch 30 when the operating state is switched in the slip state or lockup on range.

  By the way, when the oil temperature TOIL of the hydraulic oil of the lockup clutch 30 is a low temperature such as −20 ° C., when the lockup clutch 30 is to be released when the vehicle is stopped, the lockup clutch 30 is sufficiently released. In other words, the locked-up clutch piston and the front cover 110 may not be sufficiently separated from each other. This is due to the following reason. When the lockup clutch 30 is brought into the lockup off state, the spool valve 116 of the lockup relief valve 112 is set to the release side position as described above. As a result, the lockup clutch release pressure POFF is equal to the second line pressure PL2. Conducted. On the other hand, since the second line pressure PL2 and the first line pressure PL1 are regulated so as to be proportional to the engine load, the throttle opening degree, etc., the idling state, that is, the engine load when the vehicle is stopped is determined. When the throttle opening is small or the throttle opening is very small, the value of the second line pressure PL2 is also lower than when the engine load is high, such as during driving. As a result, the lockup clutch release pressure POFF is also low. The value will be lower than when traveling. In such a case, when the oil temperature TOIL of the hydraulic oil is low, the viscosity increases. Therefore, depending on the lockup clutch release pressure POFF determined assuming that the hydraulic oil is at normal temperature, The hydraulic fluid in the engagement side oil chamber 104 is not sufficiently discharged from the combination side oil chamber 104 to the engagement oil passage 102, and the hydraulic pressure in the engagement side oil chamber 104 is increased. This is due to the decline. In this specification, when the release of the lockup clutch is considered, the differential pressure ΔP is a negative value, but the absolute value of the differential pressure ΔP is referred to as the magnitude of the differential pressure ΔP. If the lock-up clutch 30 is not sufficiently released, dragging by the lock-up clutch 30 occurs.

  Therefore, the setting means 164 sets the line pressure PL to be higher than normal so that the magnitude of the differential pressure ΔP is higher than the differential pressure determined assuming a normal oil temperature. . In the present embodiment, the lockup clutch release pressure POFF is electrically connected to the second line pressure PL2 at the time of lockup off as described above, so that at least the second line pressure PL2 may be increased. That is, the secondary regulator valve 84 that regulates the second line pressure PL2 may be operated. On the other hand, since the second line pressure PL2 is based on the hydraulic pressure discharged from the regulator valve 82 for regulating the first line pressure PL1, the second line pressure PL2 can also be increased by increasing the first line pressure PL1. The pressure PL2 can be increased, and the first line pressure PL1 is increased at the same time in addition to or in place of regulating the second line pressure PL2 by the secondary regulator valve 84. Also good. The setting unit 164 includes a control start determination unit 166, a control execution unit 168, and a control end determination unit 170. Among these, the control start determination means 166 determines whether or not a predetermined control start condition is satisfied. Specifically, the control start conditions are: (1) engine speed fluctuation detected by engine speed fluctuation detecting means 174 described later, and (2) shift position PSH of shift lever 72 is “D”. (3) a predetermined time such as 1 [second] has elapsed since the turbine rotational speed NT of the torque converter 28 became zero, and (4) torque by the oil temperature determination means 176 described later. It is determined that the hydraulic oil temperature TOIL of the converter 28 is equal to or lower than the predetermined value TOILs, (5) the coolant water temperature TW of the engine 26 is equal to or lower than the predetermined value TWs, (6) by an idle determination means 172 described later. This means that all of the determination that the vehicle is in an idle state is satisfied. Among these conditions, the condition (1) is to detect that the drag by the lockup clutch 30 has occurred, and the conditions (2) and (3) are those in which the automatic transmission 10 is in the travel range and the power This means that the vehicle in which the lock-up clutch 30 is released in a state where the lockup clutch 30 is released is stopped, and a situation in which dragging can occur is meant. The predetermined time means that even if the turbine rotational speed NT becomes 0, immediately after that, the flow of hydraulic oil in the torque converter 28 caused by the load of the torque converter 28 is stabilized. This is the time it takes to stabilize. The condition (4) means a situation where the viscosity of the hydraulic oil increases as described above, the discharge amount from the engagement side oil chamber 102 decreases, and the magnitude of the differential pressure ΔP decreases. Further, the predetermined value TWs under the condition (5) is a temperature at which the magnitude of the differential pressure ΔP can be reduced by the temperature drop of the hydraulic oil, and is a value calculated in advance by experiment or simulation. ° C]. The coolant temperature TW is detected by the coolant temperature sensor 68, the shift position PSH is detected by the shift position sensor 74, and the turbine rotational speed NT is detected by the turbine rotational speed sensor 76. As described above, the condition (6) means that the line pressure PL2 determined by the engine load or the like is reduced, and as a result, the lockup release pressure POFF is reduced.

  The idle determination means 172 determines whether or not the vehicle is in an idle state based on the opening degree Acc of the accelerator 54. Specifically, for example, when the accelerator opening Acc detected by the accelerator opening sensor 56 is zero, it is determined that the vehicle is in an idle state, and otherwise, it is determined that the vehicle is not in an idle state.

  The engine speed fluctuation detecting means 174 detects whether or not the engine speed has fluctuated based on whether or not a predetermined engine speed fluctuation detection condition is satisfied. This is because the fluctuation of the engine rotation speed is caused by dragging of the lockup clutch 30. Specifically, the predetermined engine rotation speed fluctuation detection condition is (1) a change width ΔθISC of the opening degree θISC of the ISC valve 190 from the execution start time of the engine rotation speed fluctuation detection means 174 to the present time, that is, a maximum value. And the minimum value is within a predetermined value ΔθISCc, (2) the rotational speed NE of the engine 26 is in a predetermined rotational speed region, and (3) from the start of execution of the engine rotational speed fluctuation detecting means 174 to the present time. , The change width of the engine rotational speed NE for each time section divided by the first predetermined time tc1, that is, the difference ΔNE1 between the maximum value and the minimum value of the engine rotational speed NE in each predetermined time section exceeds the predetermined value ΔNE1c. (4) from the time before the second predetermined time tc2 to the present from the present It variation ΔNE2 of the engine rotational speed NE is larger than a predetermined value ΔNE2c between, is that all are met. Of these, the condition (1) is limited to fluctuations in the engine rotation speed due to the drag of the lock-up clutch 30 among the fluctuations in the engine rotation speed, and the operating condition of the engine is substantially constant. As a condition. The condition (2) is for limiting the engine rotational speed fluctuation due to the influence of the dragging of the lockup clutch 30 among the fluctuations of the engine rotational speed. For example, the dragging of the lockup clutch 30 is experimentally performed. However, when the engine speed NE is frequently generated near 800 [rpm], but hardly occurs when the engine speed NE is 600 [rpm] or lower or 1000 [rpm] or higher, the engine rotational speed NE is 700 ≦ NE [rpm] ≦ 900. It is determined to satisfy. Further, the conditions (3) and (4) are preferably used to detect a change in the engine speed preferably by simultaneously detecting whether a relatively wide time width and an instantaneous change in the engine speed occur. To do. The predetermined value ΔθISCc, the predetermined engine rotation speed region, and the predetermined times tc1, tc2, ΔNE1c, ΔNE2c are obtained in advance experimentally or by simulation, and are, for example, tc1 = 32 [ms], tc2 = 160 [ms]. ].

  The oil temperature determining means 176 determines whether or not the hydraulic oil temperature TOIL of the torque converter 28 is equal to or less than a predetermined value TOILs. Here, the hydraulic oil temperature TOIL of the torque converter 28 is detected by the AT oil temperature sensor 78, and the predetermined value TOILs is a temperature at which the magnitude of the differential pressure ΔP can be reduced by the temperature drop of the hydraulic oil. A value calculated in advance by experiment or simulation, for example, −20 [° C.].

  When the control start determination unit 166 determines that the control start condition is satisfied, the control execution unit 168 sets the line pressures PL1 and PL2 to a higher value than normal. As a result, the hydraulic pressure of the release side oil chamber 108 of the lockup clutch 30 is increased, and as a result, the magnitude of the differential pressure ΔP between the hydraulic pressure of the release side oil chamber 108 of the lockup clutch 30 and the hydraulic pressure of the engagement side oil chamber 104. Becomes larger. At this time, the line pressure is increased stepwise, and after a value increased for a predetermined time tu such as 2 [sec] is held, it is swept down over a predetermined time td such as 2 [sec]. , The original value. Even before the predetermined time tu has elapsed, if the control end determination unit 170 described later determines that the control end condition is satisfied, the increase in the line pressure is stopped. Here, as a specific degree to which the line pressures PL1 and PL2 are increased, it is sufficient that the line pressures PL1 and PL2 are increased so that the magnitude of the differential pressure ΔP can be secured to such an extent that the lockup clutch 30 is not dragged. The specific value is calculated in advance by experiment or simulation.

  The control end determination unit 170 determines whether or not a predetermined control end condition is satisfied. The control termination conditions are (1) that the vehicle is determined not to be in an idle state by idle determination means 172 described later, and (2) that the value of the turbine rotational speed NT of the torque converter 28 is equal to or greater than a predetermined value NTf. (3) The shift position PSH of the shift lever 72 is in the “N” range, (4) the rotational speed NE of the engine 26 is equal to or higher than a predetermined value NEf, (5) from the start of control by the control execution means 168. It means that any of the predetermined time tf [sec] or more has passed. Here, the predetermined values NTf and NEf are values calculated in advance by experiment or simulation. The predetermined time tf is, for example, 5 [sec] slightly longer than the total of tu, which is the time during which the line pressure is raised by the control execution means 168, and td, which is the time during which sweeping is performed. . Among these conditions, the conditions (1) and (2) are based on the engine load and the throttle opening when the vehicle is not in an idle state or the turbine rotation speed of the torque converter is equal to or higher than a predetermined value NTf. This is because, as a result of the line pressure PL2 being raised, the lockup clutch release pressure POFF also rises, so that a sufficient release state is achieved and dragging is eliminated. The condition (3) is because if the automatic transmission is in the “N” range, power is not transmitted by the automatic transmission 10, and dragging is effectively eliminated. The condition (4) is that the engine speed NE when the lock-up clutch 30 is dragged has been experimentally grasped, and dragging does not occur when the engine speed NE does not fall under this condition. The control is terminated. The condition (5) is that the increase in line pressure by the control execution means 168 is performed for a predetermined time tu and then swept down for a predetermined time td, but is not terminated due to some trouble. This is to forcibly terminate this when it has occurred.

  FIG. 10 is a flowchart for explaining a main part of the control operation of the electronic control unit 160, that is, a control operation for increasing the line pressure for preventing dragging by the lock-up clutch 30, for example, about several msec to several tens msec. It is executed repeatedly with a short cycle time.

  First, in the setting means 164, in steps (hereinafter, steps are omitted) S1 to S6 corresponding to the control start determination means 166, it is sequentially determined whether the control start condition is satisfied. That is, in S1, it is determined whether or not the shift position PSH of the shift lever 72 is in the “D” range. In S2, it is determined whether or not a change in engine rotational speed NE has been detected. In S3, it is determined whether or not a predetermined time has elapsed since the turbine rotational speed NT became zero. In S4, it is determined whether the hydraulic oil temperature TOIL of the automatic transmission 10 is equal to or lower than a predetermined value TOILs. In S5, it is determined whether or not the engine coolant temperature TW is equal to or lower than a predetermined value TWs. In S6, it is determined whether the vehicle is in an idle state.

  Among these, in particular, S2 corresponds to the engine rotational speed fluctuation detecting means 174, and the change width ΔθISC of the opening degree θISC of the ISC valve 190 from the start of execution of the engine rotational speed fluctuation detecting means 174 to the present time. That is, the difference between the maximum value and the minimum value is within a predetermined value ΔθISCc, the rotational speed NE of the engine 26 is in a predetermined rotational speed region, and the time from the start of execution of the engine rotational speed fluctuation detecting means 174 to the present time. The change width of the engine rotation speed NE for each time section divided by one predetermined time tc1, that is, the number of times that the difference ΔNE1 between the maximum value and the minimum value of the engine rotation speed NE in each predetermined time section exceeds the predetermined value ΔNE1c. The current number of times before the second predetermined time tc2 from the present Variation ΔNE2 of the engine rotational speed NE is between greater than a predetermined value DerutaNE2c, all is determined whether established in.

  S4 corresponds to the oil temperature determining means 176, and it is determined whether or not the AT oil temperature TOIL detected by the AT oil temperature sensor 78 is equal to or less than a predetermined value TOILs. S6 corresponds to the idle determination means 172, and it is determined whether or not the vehicle is in an idle state based on the accelerator opening Acc detected by the accelerator opening sensor 56.

  In S1 through S6, if the determination in any step is negative, this flowchart is temporarily terminated. On the other hand, if the determination of all steps is affirmed, S7 is subsequently executed.

  Subsequent S7 and S8 correspond to the control execution means 168. First, in S7, the line pressures PL1 and PL2 are set to values higher than the normal pressure, that is, the line pressure in the idle state in the normal “D” range.

  Further, in S8, it is determined whether a predetermined time tu has elapsed since the line pressures PL1 and PL2 were increased in S7. If the determination at this step is affirmative, S10 is executed assuming that the increase in line pressure is terminated. On the other hand, if the determination in this step is negative, this step is repeated on the assumption that the line pressure continues to rise until the predetermined time tu has elapsed.

  In S9 corresponding to the control end determination means 170, it is determined whether or not the control end condition is satisfied. That is, it is determined by an idle determination means 172 described later that the vehicle is not in an idle state, the value of the turbine rotational speed NT of the torque converter 28 is equal to or greater than a predetermined value NTf, and the shift position PSH of the shift lever 72 is “N”. Either the range, the rotational speed NE of the engine 26 is equal to or greater than a predetermined value NEf, or a predetermined time tf [sec] has elapsed since the start of control by the control execution means 168. If so, the determination in this step is affirmed, assuming that the control end condition is satisfied. If the determination in this step is affirmed, the increase in the line pressure is stopped even if it is determined in S8 that the predetermined time tu has not elapsed and the increase in the line pressure is continued. Therefore, S10 is executed. On the other hand, if the determination in this step is negative, the process returns to S8 so that the increase in line pressure continues until the predetermined time tu has elapsed.

  In S10 corresponding to the control execution means 168, the line pressures PL1 and PL2 raised in S7 are lowered to the pressure before the rise. At this time, the descent is swept down during a predetermined time td, that is, continuously decreased.

  FIG. 11 is a time chart showing the state of the control operation by the electronic control unit 160, in which the engine rotational speed NE, the line pressure PL1, and the hydraulic pressure of the engagement side oil chamber 104 of the lockup clutch 30 (lockup engagement pressure). ) The time changes of the PON and the hydraulic pressure (lockup release pressure) POFF of the release side oil chamber 108 of the lockup clutch 30 are shown on a common time axis. In this figure, the line pressure PL2 is omitted, but in the present embodiment, the line pressure PL2 is a secondary pressure of PL1 (see FIG. 3), and accompanying the increase or decrease of PL1. PL2 also changes.

  First, at time t1 in FIG. 11, it is determined by the control start determination unit 166 that the control start condition including the variation of the engine rotation speed detected by the engine rotation speed variation detection unit 174 is satisfied (S1 to S6). ). As a result, the control execution means 168 instructs the line pressures PL1 and PL2 to increase at time t2, and the line pressures PL1 and PL2 are increased at time t2 (S7). At time t3, the lockup release pressure POFF applied to the release side oil chamber 102 of the lockup clutch 30 increases. As a result, the differential pressure ΔP between the lockup release pressure POFF and the lockup engagement pressure PON can be increased, and the drag of the lockup clutch 30 can be reduced. Then, at time t4 after the elapse of a predetermined time tu from time t2 at which the control execution means 168 has been instructed to increase line pressure, the increase in line pressure ends (the determination of S8 is affirmed), and from time t4. The line pressure that has been raised over a predetermined time td until time t5 is swept down to the previous pressure.

  Note that, with respect to the engine rotational speed NE of FIG. 11, the state of the engine rotational speed NE over time when this control is not executed is represented by a broken line. As shown by the broken line, when the main control is not executed, it can be seen that the engine speed NE is repeatedly fluctuated by dragging the lockup clutch 30, while the main control shown by the solid line is Such variation does not occur in the time change of the engine speed NE when it is executed, and this change is eliminated by this control.

  As described above, according to the present embodiment, when the oil temperature determining means determines that the hydraulic oil temperature TOIL is equal to or lower than the predetermined value, and the engine rotation speed fluctuation detecting means 174 determines the rotation fluctuation of the engine 26. Since the lockup clutch disengagement pressure is set higher than the steady pressure by setting the line pressures PL1 and PL2 higher than normal by the setting means 164, the hydraulic oil temperature TOIL is lower than the predetermined value and locked up. When a change in the engine rotational speed NE that varies with the dragging of the clutch 30 is detected, the release pressure of the lockup clutch 30 is controlled, and the dragging of the lockup clutch can be suitably prevented.

  Further, according to this embodiment, when the control end condition is satisfied, the release pressure of the lock-up clutch 30 is returned to the steady pressure, so compared with the case where the release pressure is constantly set high at a low oil temperature, Air suction due to an increase in the amount of oil sucked from the strainer can be suppressed.

  Further, according to the present embodiment, the end condition is that the engine 26 provided in the vehicle is not in an idle state, and the rotational speed NT of the turbine of the torque converter 28 as the fluid transmission device is a predetermined value or more. One of the following holds: the rotational speed NE of the engine 26 is equal to or higher than a predetermined value, that a predetermined time has elapsed since the start of the operation of the setting means 164, or that the automatic transmission 10 is in the N range. If any of these conditions is satisfied, the release pressure of the lockup clutch is returned to the steady pressure by the setting means. Therefore, when the release pressure is constantly set high at a low oil temperature, In comparison, air suction due to an increase in the amount of oil sucked from the strainer can be suppressed.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  In the present embodiment, the second line pressure PL2 is provided as the secondary pressure of the first line pressure PL1, but the present invention is not limited to this, and the first line pressure and the second line pressure are provided as independent hydraulic systems. Also good. Alternatively, only the first line pressure may be provided without providing the second line pressure. In these embodiments, the control execution unit 168 may increase the line pressure so as to increase the release pressure POFF of the lockup clutch 30.

  In the present embodiment, the line pressures PL1 and PL2 are increased only by a predetermined value by the control execution means 168. However, the present invention is not limited to this. For example, the differential pressure ΔP is sufficient. Alternatively, the line pressures PL1 and PL2 may be increased by feedback control so as to eliminate fluctuations in the engine rotation speed.

  In this embodiment, the control start condition is that the engine speed fluctuation is detected by the engine speed fluctuation detecting means 174, the shift position PSH of the shift lever 72 is in the “D” range, the torque converter For example, when a predetermined time such as 1 [second] has elapsed since the turbine rotation speed NT of 28 is zero, the hydraulic oil temperature TOIL of the torque converter 28 is less than or equal to a predetermined value TOILs by the oil temperature determination means 176. It has been determined that all of the determination, that the coolant temperature TW of the cooling water of the engine 26 is equal to or lower than the predetermined value TWs, and that the vehicle is determined to be in an idle state by the idle determination unit 172 are satisfied. At least of these, the AT oil temperature TOIL is not more than the predetermined value TOILs, and the engine rotational speed fluctuation detection 174 by but also produce a certain effect, subject to two points that the variation of the engine rotational speed is detected.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

1 is a skeleton diagram illustrating a configuration of an automatic transmission for a vehicle to which the present invention is applied. FIG. 2 is an operation chart for explaining a combination of operations of the hydraulic friction engagement device when establishing a plurality of gear stages of the vehicle automatic transmission of FIG. 1. It is a circuit diagram regarding the linear solenoid valve which controls the action | operation of each hydraulic actuator of a clutch and a brake, and a lockup clutch, Comprising: It is a figure which shows the hydraulic control circuit as a hydraulic control apparatus. It is a figure for explaining the engagement pressure control of the second brake and the torque capacity control of the lockup clutch by the linear solenoid valve that is switched by the switching circuit, including schematic diagrams of the second brake control circuit and the switching circuit. FIG. 2 is a block diagram illustrating a main part of a control system provided in the vehicle for controlling the automatic transmission of FIG. 1 and the like. It is a figure explaining the operation position of the shift lever of FIG. It is a functional block diagram explaining the principal part of the control function by the electronic controller of FIG. It is a figure which shows an example of the shift map used in the shift control of an automatic transmission. It is a figure explaining an example of the lockup area | region diagram used for control of the lockup clutch in a torque converter. 6 is a flowchart for explaining a main part of the control operation of the electronic control device of FIG. 5, that is, a control operation for setting a release pressure of the lockup clutch. It is a time chart showing a mode that the control by the electronic controller of FIG. 5 is performed.

Explanation of symbols

10: Automatic transmission 26 for vehicle: Engine 28: Torque converter (fluid transmission)
30: Lock-up clutch 72: Shift lever (operating device)
160: Electronic control device (hydraulic control device)
164: Setting means 174: Engine rotational speed fluctuation detecting means (rotational fluctuation determining means)
176: Oil temperature determining means POFF: Lock-up clutch release pressure

Claims (3)

A control device for a lockup clutch for a vehicle provided in a fluid transmission device for transmitting engine output to an automatic transmission,
Oil temperature determining means for determining that the hydraulic oil temperature is equal to or lower than a predetermined value;
Rotation fluctuation determining means for determining rotation fluctuation of the engine;
And a setting means for setting a lock-up clutch release pressure for releasing the lock-up clutch higher than a steady pressure when the oil temperature is a low oil temperature equal to or lower than the predetermined value and an engine rotation fluctuation is detected. Control device for a vehicle lock-up clutch.   The control device for a lockup clutch for a vehicle according to claim 1, wherein the setting means returns the release pressure of the lockup clutch to a steady pressure when a predetermined end condition is satisfied.   The end condition is that the engine is not in an idle state, the rotational speed of the turbine of the fluid transmission device is a predetermined value or more, the rotational speed of the engine is a predetermined value or more, and the operation of the setting means is started. 3. The vehicle lockup clutch control device according to claim 1, wherein either a predetermined time has elapsed since the vehicle has elapsed, or the automatic transmission is in the N range.

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