JP5533556B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device in which a lockup clutch is disposed on a transmission path of a driving force. In particular, the present invention relates to improved control for improving the fuel consumption rate.

  Conventionally, in a vehicle equipped with an engine, the transmission ratio between the engine and the drive wheel is automatically set as a transmission that appropriately transmits the torque and rotation speed generated by the engine to the drive wheel according to the traveling state of the vehicle. An automatic transmission that is optimally set for the motor is known.

  As an automatic transmission mounted on a vehicle, for example, a planetary gear type transmission that sets a gear ratio (gear stage) using a clutch and brake and a planetary gear device, or a belt type that adjusts the gear ratio steplessly There is a continuously variable transmission (CVT).

  Further, in a vehicle equipped with this type of automatic transmission, a fluid power transmission device such as a fluid coupling or a torque converter is disposed on a driving force transmission path between the engine and the automatic transmission. . Further, a fluid power transmission device having a lock-up clutch is known (see, for example, Patent Document 1 below). This lock-up clutch enables frictional engagement with hydraulic pressure of hydraulic oil (hereinafter sometimes referred to as oil), thereby enabling direct connection between the input side and the output side of the fluid power transmission device.

  In a vehicle equipped with such a fluid power transmission device with a lock-up clutch, for example, the lock-up clutch is operated using the hydraulic pressure (line pressure) of a hydraulic control system including the hydraulic control of the automatic transmission as a source pressure. By controlling the hydraulic pressure applied to the lockup clutch, the engagement state (fully engaged state), half-engaged state (also called the flex lockup state or slip state), and the release state of the lockup clutch are controlled.

  Specifically, in the case of a torque converter with a lock-up clutch, a solenoid valve for lock-up differential pressure control, a lock-up control valve, etc. are used to connect the torque converter between the engagement-side oil chamber and the release-side oil chamber. Control of engagement / half-engagement / release of the lock-up clutch is performed by controlling the differential pressure (lock-up differential pressure) based on the lock-up differential pressure instruction value (for example, duty control of the solenoid valve). .

  Further, as described in Patent Document 2, in order to improve the fuel consumption rate by extending the duration of fuel cut when the vehicle is decelerating (during coasting when the accelerator is OFF: also called coasting). In addition, it is known to execute a lockup control during deceleration for maintaining the lockup clutch in an engaged state.

  In this deceleration lock-up control, the engine is driven to rotate with power on the driving wheel side, and the vehicle speed is higher by a predetermined speed than the predetermined vehicle speed (the engine stall speed (for example, 500 rpm)). The engagement state of the lockup clutch and the fuel cut state are continued until the vehicle speed decreases to a vehicle speed corresponding to (for example, 20 km / h): hereinafter referred to as “lockup release vehicle speed”. When the vehicle speed drops to the lockup release vehicle speed, the lockup clutch is released and the engine fuel injection is started to restart the engine to prevent engine stall.

JP 2009-275858 A JP 2002-234340 A

Incidentally, in a vehicle fluid type power transmission device is mounted with a lock-up clutch as described above, as a method for achieving a further improvement of the fuel consumption rate, Lock steady when click-up clutch is in the engaged state It is conceivable to set the engine speed low during traveling. In other words, during steady running, i.e., in a situation which is an operation amount of the accelerator pedal is constant, since there is no driver's acceleration demand, to reduce the gear ratio of the transmission while maintaining the current vehicle speed, whereby the engine speed It is possible to reduce the fuel consumption (fuel injection amount from the injector).

However, in the set lower engine speed in the steady running in a single, if sudden braking request of the vehicle has occurred (when the brake pedal is depressed significantly by the driver), the lock-up clutch is engaged As a result, the engine speed also decreases rapidly as the rotational speed of the drive wheels rapidly decreases due to sudden braking of the vehicle. In such a situation, the timing by remote destination that the lock-up clutch is released state when the engine speed is've reached the stall rotational speed, there is a possibility that led to engine stall.

  As a control for avoiding such an engine stall, the lockup differential pressure is set low, and when the vehicle is suddenly braked, the lockup clutch can be released before the engine speed decreases to the stall speed. It has been broken. For example, when the lock-up clutch is in the engaged state, the lock-up differential pressure is set so that the engagement pressure becomes the minimum necessary value, or the lock-up clutch is slid (slipped). For example, a lockup differential pressure is set.

  However, when the lockup clutch is slipped, the reliability of the control may not be sufficiently obtained depending on the engine operating state. For example, depending on the engine speed, the temperature of hydraulic oil for engaging the lock-up clutch (CVT oil temperature), and the engine coolant temperature, the actual lock-up differential pressure may deviate from the lock-up differential pressure command value. May occur, and the target slip amount may not be obtained. That is, when the actual slip amount is small with respect to the target slip amount (for example, the slip amount in which the difference between the engine speed and the turbine speed is 100 rpm) (actual lockup with respect to the lockup differential pressure instruction value). When the differential pressure is shifted to the higher side), the time required to release the lockup clutch becomes longer, and the engine speed reaches the stall speed before the lockup clutch is released. It may lead to a stall. For this reason, the control for slipping the lock-up clutch cannot always be performed, and the control is limited to a specific engine operating state (only when the temperature of the hydraulic oil or the coolant temperature is within a predetermined range). Will be).

  Similarly, when the lock-up clutch is engaged, if the actual lock-up differential pressure is shifted to the higher side with respect to the minimum required lock-up differential pressure, the lock-up clutch is released. It takes longer time. For this reason, there is a possibility that the engine speed reaches the stall speed before the lock-up clutch is released and the engine stalls.

Therefore, in practice, it may be set to a higher engine speed during steady running, if the engine stall even deviation of the actual lock-up differential pressure with respect to the lock-up differential pressure instruction value has occurred The current situation is to prevent this from occurring. In this, the steady running Ri is Na difficult to sufficiently reduce the amount of fuel injection during, to achieve further improvement of fuel consumption rate is limited.

  The present invention has been made in view of such points, and an object of the present invention is to further improve the fuel consumption rate for a vehicle equipped with a fluid power transmission device having a lock-up clutch. An object of the present invention is to provide a control device for a vehicle.

-Principle of solving the problem-
Resolution principle of the present invention which were taken in order to achieve the above object, the presence or absence of completion of the hydraulic learning of the lockup clutch (another or learning completion or incompletion), and, depending on the control state of the lock-up clutch Te, and to change the engine speed during steady running. That is, the hydraulic pressure learning of the lock-up clutch so that by setting the rotational speed of the steady running during that put when complete than when it is not completed less, improvement of fuel consumption rate can be reduced.

Specifically, the present invention relates to a vehicle control device in which a lock-up clutch capable of switching between a fully engaged state, a slip state, and a released state is provided in a driving force transmission path from a driving source to driving wheels. Assuming Even if the lockup differential pressure instruction value is changed so that the slip rotation speed of the lockup clutch is set to a predetermined slip rotation speed, the lockup differential pressure instruction value becomes a predetermined value. When the slip rotation speed of the lockup clutch does not reach the predetermined slip rotation speed, a learning operation for learning and correcting the lockup differential pressure instruction value by a predetermined learning value is performed, and the slip rotation speed of the lockup clutch is set to a predetermined value. When the slip rotation speed of the lockup clutch does not reach the predetermined slip rotation speed even when the feedback value for setting the slip rotation speed reaches a predetermined value, the differential pressure learning of the lockup clutch is not completed, When the feedback value is below the predetermined value, the slip rotation speed of the lockup clutch is equal to the predetermined slip rotation speed. It is determined that the differential pressure learning of the lock-up clutch has been completed when. In addition, when the lockup clutch is in a fully engaged state or slipped state, when the differential pressure learning of the lockup clutch is not completed during steady running in which the accelerator pedal is depressed and the operation amount is constant. When the sudden braking request of the vehicle occurs during the steady running, assuming that the amount of deviation of the actual engagement pressure with respect to the engagement pressure command value of the lockup clutch is larger than when the differential pressure learning is completed In order to ensure a long time from the start of the sudden braking request until the rotational speed of the drive source reaches the stall rotational speed, the actual engagement pressure is higher than the engagement pressure instruction value of the lockup clutch. Even if there is a deviation, the rotation speed of the drive source is set so that the lockup clutch can be switched to the released state before the rotation speed of the drive source reaches the stall rotation speed. On the other hand, when the lockup clutch is in the fully engaged state or slipped state, when the differential pressure learning of the lockup clutch is completed during steady running where the accelerator pedal is depressed and the operation amount is constant. The difference in actual engagement pressure with respect to the engagement pressure command value of the lock-up clutch is small compared to the case where the differential pressure learning is not completed. The rotation speed of the drive source can be switched to the released state before reaching the stall rotation speed, and is lower than the rotation speed of the drive source when the differential pressure learning is not completed. Set to the rotational speed of the drive source. Then, during the steady running when the lockup clutch is in the fully engaged state or the slip state, the value of the rotational speed of the drive source is set to be low as the differential pressure learning of the lockup clutch is completed. In this case, the transmission gear ratio for maintaining the current vehicle speed is obtained as a value smaller than the transmission gear ratio when differential pressure learning is not completed, and the transmission is controlled so that the obtained transmission gear ratio is obtained. It is configured to.

  Due to this specific matter, when the lockup clutch is in the fully engaged state or slip state, if the differential pressure learning of the lockup clutch is not completed, the value of the rotational speed of the drive source during steady running is compared. Set high. As a result, for example, when a sudden braking request for the vehicle occurs during steady running, a long time is required from the start of the sudden braking request until the engine speed reaches the stall rotational speed. Even if the actual engagement pressure is deviated from the indicated value, the lockup clutch can be switched to the released state before the rotational speed of the drive source reaches the stall rotational speed.

  In addition, when the lockup clutch is in a fully engaged state or slip state, if the differential pressure learning of the lockup clutch is completed, the value of the rotational speed of the drive source during steady running is relatively low. Set. In other words, since the differential pressure learning has been completed and the actual engagement pressure deviation amount with respect to the engagement pressure command value for the lockup clutch is small, the lock is applied from the time when the rotational speed of the drive source is reduced to the set value. If the release operation of the up clutch is started, the lockup clutch can be switched to the released state before the rotational speed of the drive source reaches the stall rotational speed. That is, it is possible to set the engine speed at a normal time low without causing the drive source to stall, and the fuel consumption rate can be greatly improved.

  As a specific setting operation when changing the value of the rotational speed of the drive source during the steady running, the drive source during the steady running set when the lockup clutch is in the fully engaged state is used. The value of the rotational speed of the drive source during steady running, which is set when the lockup clutch is in the slip state, is set lower than the rotational speed value.

If lock-up clutch is in a slipping state, the release command signal is transmitted with respect to the lock-up clutch, the lock-up clutch is switched from the slip state to the released state, be a relatively short time release state Can do. That is, even if the rotational speed of the drive source during steady running is set to a relatively low value, the lockup clutch can be released before the rotational speed of the drive source reaches the stall rotational speed. For this reason, when the lockup clutch is in the slip state, the rotational speed of the drive source during steady running is set to a relatively low value so that the fuel consumption rate can be improved.

  On the other hand, when the lockup clutch is in the fully engaged state, when the release command signal is transmitted to the lockup clutch, the lockup clutch is switched from the fully engaged state to the released state. The time until the release state is reached is longer than that in the slip state. In other words, if the rotational speed of the drive source during steady running is set to the same value as in the slip state in this fully engaged state, the timing before the lockup clutch is released is set. In addition, the rotational speed of the drive source may reach the stall rotational speed, leading to a stall. Therefore, the rotational speed of the drive source during steady running when the lockup clutch is in the fully engaged state is set higher than the rotational speed of the drive source during steady running when the lockup clutch is in the slip state. A long time is required until the rotational speed of the source reaches the stall rotational speed, and the lockup clutch can be switched to the released state before reaching the stall rotational speed.

In the present invention, the presence or absence of completion of the hydraulic learning of the lock-up clutch, and, depending on the control state of the lock-up clutch, and to change the engine speed during steady running. Therefore, the hydraulic pressure learning of the lock-up clutch becomes possible to set the engine speed put that steady traveling in when complete than when it is not completed less, achieve further improvement of fuel consumption rate be able to.

It is a figure showing a schematic structure of a powertrain of a vehicle concerning an embodiment. It is a figure which shows the hydraulic circuit which concerns on engagement / release control of a lockup clutch. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows an example of the shift map used for the shift control of a belt-type continuously variable transmission. It is a figure which shows the lockup clutch action | operation map referred when it exists in the engine operating state in which slip control at the time of deceleration is permitted. It is a figure which shows the lockup clutch action | operation map referred when it exists in the engine operating state in which slip control at the time of deceleration is prohibited. It is a flowchart figure which shows the procedure of the control operation | movement for setting a lockup release vehicle speed and the engine speed at the time of a steady state. It is a figure which shows an example of the lockup release vehicle speed set according to a lockup clutch engagement state and a lockup differential pressure learning state, and the engine speed at the time of a steady state. It is a flowchart figure which shows the procedure of lockup differential pressure learning completion determination operation | movement.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where the vehicle control apparatus which concerns on this invention is applied to the vehicle carrying a belt-type continuously variable transmission (CVT) as a transmission.

  FIG. 1 is a diagram showing a schematic configuration of a vehicle power train in the present embodiment.

  The vehicle according to the present embodiment is an FF (front engine / front drive) type vehicle, which is an engine (internal combustion engine: drive source) 1 that is a driving power source, a torque converter 2 as a fluid power transmission device, front and rear An advance switching device 3, a belt-type continuously variable transmission 4, a reduction gear device 5, a differential gear device 6, an ECU (Electronic Control Unit) 8 (see FIG. 3), and the like are mounted. A control device for the lockup clutch 24 is configured by the lockup control circuit 200 (a part of the hydraulic control circuit 20) and the like.

  A crankshaft 11, which is an output shaft of the engine 1, is connected to the torque converter 2, and the output of the engine 1 is transmitted from the torque converter 2 through the forward / reverse switching device 3, the belt type continuously variable transmission 4, and the reduction gear device 5. Are transmitted to the differential gear device 6 and distributed to the left and right drive wheels 7L, 7R.

  The parts of the engine 1, the torque converter 2, the forward / reverse switching device 3, the belt-type continuously variable transmission 4, and the ECU 8 will be described below.

-Engine-
The engine 1 is a multi-cylinder gasoline engine, for example. The intake air amount sucked into the engine 1 is adjusted by an electronically controlled throttle valve 12. The throttle valve 12 can electronically control the throttle opening independently of the driver's accelerator pedal operation, and the opening (throttle opening) is detected by the throttle opening sensor 102. . Further, the coolant temperature of the engine 1 is detected by a water temperature sensor 103.

  The throttle opening of the throttle valve 12 is driven and controlled by the ECU 8 (see FIG. 3). Specifically, the optimum intake air amount (in accordance with the operating state of the engine 1 such as the engine speed Ne detected by the engine speed sensor 101 and the accelerator pedal depression amount (accelerator operation amount Acc) of the driver). The throttle opening of the throttle valve 12 is controlled so as to obtain a target intake air amount. More specifically, the actual throttle opening of the throttle valve 12 is detected using the throttle opening sensor 102, and the actual throttle opening becomes the throttle opening (target throttle opening) at which the target intake air amount is obtained. The throttle motor 13 of the throttle valve 12 is feedback controlled so as to match.

-Torque converter-
The torque converter 2 includes an input-side pump impeller 21, an output-side turbine runner 22, a stator 23 that develops a torque amplification function, and the like, and fluid is supplied between the pump impeller 21 and the turbine runner 22. Transmit power. The pump impeller 21 is connected to the crankshaft 11 of the engine 1. The turbine runner 22 is connected to the forward / reverse switching device 3 via the turbine shaft 28.

  The torque converter 2 is provided with a lockup clutch (lockup clutch mechanism) 24 that directly connects the input side and the output side of the torque converter 2. The lock-up clutch 24 is configured such that a differential pressure between the hydraulic pressure in the engagement-side oil chamber 25 and the hydraulic pressure in the release-side oil chamber 26 (lock-up differential pressure = hydraulic pressure Pon in the engagement-side oil chamber 25−release-side oil chamber). By controlling the hydraulic pressure Poff) in 26, full engagement, half engagement (engagement in the slip state) or release is achieved.

  By completely engaging the lockup clutch 24, the pump impeller 21 and the turbine runner 22 rotate integrally. Further, by engaging the lockup clutch 24 in a predetermined slip state (half-engaged state), the turbine runner 22 rotates following the pump impeller 21 with a predetermined slip amount when the engine driving force is transmitted. On the other hand, the lockup clutch 24 is released by setting the lockup differential pressure to be negative or the same. The torque converter 2 is provided with a mechanical oil pump (hydraulic pressure generating source) 27 that is connected to and driven by the pump impeller 21.

-Forward / reverse switching device-
The forward / reverse switching device 3 includes a double pinion type planetary gear mechanism 30, a forward clutch (input clutch) C1, and a reverse brake B1.

  The sun gear 31 of the planetary gear mechanism 30 is integrally connected to the turbine shaft 28 of the torque converter 2, and the carrier 33 is integrally connected to the input shaft 40 of the belt type continuously variable transmission 4. The carrier 33 and the sun gear 31 are selectively connected via the forward clutch C1, and the ring gear 32 is selectively fixed to the housing via the reverse brake B1.

  The forward clutch C1 and the reverse brake B1 are hydraulic friction engagement elements that are engaged and released by the hydraulic control circuit 20, and the forward clutch C1 is engaged and the reverse brake B1 is released. As a result, the forward / reverse switching device 3 is integrally rotated to establish (achieve) the forward power transmission path. In this state, the forward driving force is transmitted to the belt type continuously variable transmission 4 side.

  On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the forward / reverse switching device 3 establishes (achieves) a reverse power transmission path. In this state, the input shaft 40 rotates in the reverse direction with respect to the turbine shaft 28, and the driving force in the reverse direction is transmitted to the belt type continuously variable transmission 4 side. Further, when both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 3 becomes neutral (interrupted state) for interrupting power transmission.

-Belt type continuously variable transmission-
The belt-type continuously variable transmission 4 includes an input-side primary pulley 41, an output-side secondary pulley 42, a metal belt 43 wound around the primary pulley 41 and the secondary pulley 42, and the like.

  The primary pulley 41 is a variable pulley having a variable effective diameter, and a fixed sheave 411 fixed to the input shaft 40 and a movable sheave 412 disposed on the input shaft 40 in a state in which sliding is possible only in the axial direction. And is composed of. Similarly, the secondary pulley 42 is a variable pulley whose effective diameter is variable, and is a fixed sheave 421 fixed to the output shaft 44 and a movable sheave arranged on the output shaft 44 so as to be slidable only in the axial direction. 422.

  A hydraulic actuator 413 for changing the V groove width between the fixed sheave 411 and the movable sheave 412 is disposed on the movable sheave 412 side of the primary pulley 41. Similarly, a hydraulic actuator 423 for changing the V groove width between the fixed sheave 421 and the movable sheave 422 is also arranged on the movable sheave 422 side of the secondary pulley 42.

  In the belt type continuously variable transmission 4 having the above-described structure, by controlling the hydraulic pressure of the hydraulic actuator 413 of the primary pulley 41, the V groove widths of the primary pulley 41 and the secondary pulley 42 change, and the engagement diameter of the belt 43 ( The effective diameter is changed, and the speed ratio γ (speed ratio γ = input shaft speed Nin / output shaft speed Nout) continuously changes. The hydraulic pressure of the hydraulic actuator 423 of the secondary pulley 42 is controlled such that the belt 43 is clamped with a predetermined clamping pressure that does not cause belt slip. These controls are executed by the ECU 8 and the hydraulic control circuit 20 (see FIG. 3).

  The hydraulic control circuit 20 is provided with a linear solenoid valve, an on / off solenoid valve, and the like. By controlling the excitation / non-excitation of these solenoid valves and switching the hydraulic circuit, the shift control of the belt type continuously variable transmission 4 is performed. And engage / release control of the lock-up clutch 24. Excitation / non-excitation of the linear solenoid valve and the on / off solenoid valve of the hydraulic control circuit 20 is controlled by a solenoid control signal (instructed hydraulic signal) from the ECU 8. A specific configuration and operation of the lockup control circuit 200 for performing engagement / release control of the lockup clutch 24 will be described below.

-Lock-up control circuit-
FIG. 2 is a circuit diagram showing the lockup control circuit 200 that performs engagement / release control of the lockup clutch 24 in the hydraulic control circuit 20.

  The lockup control circuit 200 includes a lockup control valve 201, a pressure regulating valve 220, a linear solenoid valve (SLU solenoid valve) 230 for lockup differential pressure control, and the like.

  The lockup control valve 201 is provided with a pair of first line pressure port 202 and second line pressure port 203, and further provided with a release side port 205 and a signal pressure port 206. The original pressure (lock-up pressure) from the pressure regulating valve 220 is supplied to the first line pressure port 202 and the second line pressure port 203. The pressure regulating valve 220 regulates the control pressure (line pressure) in the hydraulic control circuit 20 (see FIG. 3) and supplies it to the lockup control valve 201 and the engagement side oil chamber 25 of the torque converter 2. Further, the release side port 205 of the lockup control valve 201 is connected to the release side oil chamber 26 of the torque converter 2.

  The SLU solenoid valve 230 is a linear solenoid valve, and outputs the control signal pressure PSLU when in an excited state, and stops outputting the control signal pressure PSLU when in a non-excited state. In this SLU solenoid valve 230, the excitation current is duty-controlled in accordance with the lockup differential pressure instruction value PD output from the ECU 8, and the control signal pressure PSLU continuously changes. The control signal pressure PSLU output from the SLU solenoid valve 230 is supplied to the signal pressure port 206 of the lockup control valve 201.

  In the lockup control circuit 200 described above, the SLU solenoid valve 230 is excited in accordance with the lockup differential pressure instruction value PD output from the ECU 8, and the control signal pressure PSLU is supplied to the signal pressure port 206 of the lockup control valve 201. Then, in this lockup control valve 201, as shown in the right half of the center line in FIG. 2, the spool 207 is moved upward against the urging force of the compression coil spring 208 (ON state). In this state, the release side port 205 communicates with the drain port 209 while the lockup pressure is supplied to the engagement side oil chamber 25 of the torque converter 2, so that the hydraulic oil in the release side oil chamber 26 is discharged. The drain is engaged and the lockup clutch 24 is engaged (ON).

  At this time, the lockup differential pressure PLU, that is, the hydraulic pressure Pon in the engagement-side oil chamber 25 of the lockup clutch 24 and the release-side oil chamber 26 according to the duty ratio of the lockup differential pressure instruction value PD output from the ECU 8. The differential pressure with respect to the internal hydraulic pressure Poff can be continuously controlled, and the engagement force of the lockup clutch 24 can be continuously changed according to the lockup differential pressure PLU. That is, the engagement force when the lockup clutch 24 is in the engaged state can be controlled, and the slip amount when the lockup clutch 24 is in the slip state can be controlled.

  On the other hand, when the SLU solenoid valve 230 is de-energized and the output of the control signal pressure PSLU from the SLU solenoid valve 230 is stopped, the lockup control valve 201 is compressed as shown in the left half of the center line in FIG. The spool 207 is moved downward by the urging force of the coil spring 208 and is moved to the original position (OFF state).

  In this OFF state, the second line pressure port 203 and the release side port 205 communicate with each other, and the lockup pressure is supplied to the release side oil chamber 26 of the lockup clutch 24 through these ports 203 and 205. The oil pressure in the release side oil chamber 26 and the oil pressure in the engagement side oil chamber 25 are equalized, and the lockup clutch 24 is released (OFF).

-ECU-
As shown in FIG. 3, the ECU 8 includes a CPU 81, a ROM 82, a RAM 83, a backup RAM 84, and the like.

  The ROM 82 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 81 executes arithmetic processing based on various control programs and maps stored in the ROM 82. The RAM 83 is a memory for temporarily storing calculation results in the CPU 81 and data input from each sensor. The backup RAM 84 is a non-volatile memory for storing data to be saved when the engine 1 is stopped. is there.

  The CPU 81, ROM 82, RAM 83, and backup RAM 84 are connected to each other via a bus 87 and are connected to an input interface 85 and an output interface 86.

  The input interface 85 of the ECU 8 includes an engine speed sensor 101, a throttle opening sensor 102, a water temperature sensor 103, a turbine speed sensor 104, an input shaft speed sensor 105, a vehicle speed sensor 106, an accelerator opening sensor 107, and a CVT oil temperature. A sensor 108, a brake pedal sensor 109, and a lever position sensor 110 that detects a lever position (operation position) of the shift lever 9 are connected. The input interface 85 allows the output signal of each sensor, that is, the rotation speed of the engine 1 (engine rotation speed) Ne, the opening degree θth of the throttle valve 12, the cooling water temperature Tw of the engine 1, the rotation speed of the turbine shaft 28 ( Turbine speed Nt, input shaft 40 speed (input shaft speed) Nin, vehicle speed V, accelerator pedal operation amount (accelerator opening) Acc, oil pressure of hydraulic control circuit 20 (CVT oil) The ECU 8 is supplied with signals indicating the temperature Thc), the presence / absence of operation of the foot brake as a service brake (brake ON / OFF), the lever position (operation position) of the shift lever 9, and the like.

  The output interface 86 is connected to the throttle motor 13, the fuel injection device 14, the ignition device 15, the hydraulic control circuit 20 (lockup control circuit 200), and the like.

  Here, of the signals supplied to the ECU 8, the turbine rotational speed Nt coincides with the input shaft rotational speed Nin during forward travel where the forward clutch C1 of the forward / reverse switching device 3 is engaged, and the vehicle speed V is the belt type This corresponds to the rotational speed (output shaft rotational speed) Nout of the output shaft 44 of the step transmission 4. The accelerator operation amount Acc represents the driver's requested output amount.

  The shift lever 9 includes a parking position “P” for parking, a reverse position “R” for reverse traveling, a neutral position “N” for interrupting power transmission, a drive position “D” for forward traveling, During forward running, the gear ratio γ of the belt type continuously variable transmission 4 is selectively operated to each position such as a manual position “M” where the manual operation can increase or decrease the speed ratio γ.

  The manual position “M” includes a plurality of ranges in which a downshift position and an upshift position for increasing / decreasing the speed ratio γ, or a plurality of speed ranges in which the upper limit of the speed range (the side where the speed ratio γ is smaller) are different can be selected. Position etc. are provided.

  The lever position sensor 110 is, for example, a parking position “P”, a reverse position “R”, a neutral position “N”, a drive position “D”, a manual position “M”, an upshift position, a downshift position, or a range position. A plurality of ON / OFF switches for detecting that the shift lever 9 is operated are provided. In order to change the gear ratio γ manually, a downshift switch, an upshift switch (so-called paddle switch), a lever, or the like can be provided on the steering wheel or the like separately from the shift lever 9.

  The ECU 8 controls the output of the engine 1, the shift control of the belt-type continuously variable transmission 4, the belt clamping pressure control, and the engagement / disengagement of the lock-up clutch 24 based on the output signals of the various sensors described above. Perform release control. Further, the ECU 8 performs lock-up control during deceleration, lock-up smooth engagement control (hydraulic control to avoid a shock when the lock-up clutch 24 is engaged), lock-up smooth OFF control (when releasing the lock-up clutch 24). (Hydraulic control to avoid shock). Since the above lock-up smooth engagement control and lock-up smooth OFF control are already known, description thereof is omitted here. The details of the deceleration lockup control will be described later.

  Output control of the engine 1 is performed by the throttle motor 13, the fuel injection device 14, the ignition device 15, the ECU 8, etc., and the shift control of the belt type continuously variable transmission 4, the belt clamping pressure control, and the engagement of the lockup clutch 24. The release control is performed by the hydraulic control circuit 20 (lock-up control circuit 200). The throttle motor 13, the fuel injection device 14, the ignition device 15, and the hydraulic control circuit 20 are controlled by the ECU 8.

  For example, as shown in FIG. 4, the shift control of the belt-type continuously variable transmission 4 is performed based on a target shift on the input side from a shift map set in advance with the accelerator operation amount Acc representing the driver's required output amount and the vehicle speed V as parameters. The number (target rotational speed) Nint is calculated, and the shift control of the belt-type continuously variable transmission 4 according to the deviation, that is, the primary pulley 41 so that the actual input shaft rotational speed Nin matches the target rotational speed Nint. The hydraulic pressure Pin is controlled by supplying and discharging the hydraulic oil to and from the hydraulic actuator 413, and the gear ratio γ continuously changes.

  The map in FIG. 4 corresponds to the shift conditions, and the target rotational speed Nint is set such that the greater the vehicle speed V is and the accelerator operation amount Acc is, the greater the gear ratio γ is. Further, since the vehicle speed V corresponds to the output shaft rotational speed Nout, the target rotational speed Nint, which is the target value of the input shaft rotational speed Nin, corresponds to the target speed ratio, and the minimum speed ratio γmin of the belt type continuously variable transmission 4 is It is set within the range of the maximum gear ratio γmax.

-Lock-up clutch operation map-
The above-described switching operation of the fully engaged state, the half-engaged state, and the released state of the lockup clutch 24 is performed in accordance with, for example, the lockup clutch operation map shown in FIGS. This lock-up clutch operation map uses the vehicle speed V and the accelerator opening Acc as parameters, and the lock-up clutch 24 is fully engaged (completely locked-up), half-engaged according to the vehicle speed V and the accelerator opening Acc. A map for switching between a combined state (referred to as a flex lockup state or a slip state) and a released state (torque control state), and is stored in the ROM 82.

  Further, in this lockup clutch operation map, an accelerator ON operation region and an accelerator OFF operation region are set. The accelerator ON operation area is locked according to the vehicle speed V detected by the vehicle speed sensor 106 and the accelerator opening Acc detected by the accelerator opening sensor 107 when the driver depresses the accelerator pedal. This is an operation region in which the engagement state (control state) of the up clutch 24 is switched. On the other hand, in the accelerator OFF operation region, the engagement state of the lockup clutch 24 is switched according to the vehicle speed V when the accelerator pedal is not depressed by the driving state (the accelerator opening is “0”). It is an operation area.

  In other words, in the accelerator ON operation region where the driver depresses the accelerator pedal, the complete engagement region (complete lockup operation region), slip region (flex lockup) based on the vehicle speed V and the accelerator opening Acc. Operation region) or release region (torque operation region), and the lockup control valve 201 is controlled so that the operation of the determined region is performed to fully engage the lockup clutch 24. In this case, the control for setting the state of either half-engagement or release is executed. It should be noted that the lock-up clutch 24 is based on a lock-up clutch operation map (a map for controlling the lock-up clutch 24 according to the vehicle speed V and the throttle opening θth) instead of the accelerator opening Acc. The state may be switched.

  In the flex lockup operation region, the power transmission loss of the torque converter 2 is suppressed as much as possible while absorbing the rotational fluctuation of the engine 1 for the purpose of improving the fuel efficiency as much as possible without impairing drivability. In addition, slip control of the lockup clutch 24 is executed. For slip control of the lock-up clutch 24, the rotational speed difference (slip amount) NSLP (= Ne−Nt) between the turbine rotational speed (turbine rotational speed) Nt and the engine rotational speed (engine rotational speed) Ne is set to the target rotational speed difference. In order to control the target slip amount (for example, 50 rpm), a drive signal is output to the lockup control valve 201 that controls the lockup clutch 24.

  On the other hand, in the accelerator-off operation region where the driver does not depress the accelerator pedal, the lock-up clutch 24 is fully engaged in order to improve the fuel consumption rate by extending the duration of fuel cut. Deceleration lockup control to maintain and deceleration slip control to maintain the lockup clutch 24 in the half-engaged state are performed according to the vehicle speed V.

  In other words, in these deceleration lockup control and deceleration slip control, the engine 1 is put into a driven state in which it is rotationally driven by the power on the drive wheels 7L, 7R side until the vehicle speed drops to a predetermined vehicle speed (lockup release vehicle speed). The fuel cut state is continued and the lockup clutch is engaged or slipped. As described above, when the lock-up clutch 24 is completely engaged or slipped during deceleration, the engine rotation speed Ne is increased to the vicinity of the turbine rotation speed Nt, so that the control state (fuel cut state) for suppressing the fuel supply amount to the engine 1 is increased. ) Is maintained for a long period of time, thereby improving the fuel consumption rate. When the vehicle speed drops to the lockup release vehicle speed, the lockup clutch 24 is released and the fuel injection of the engine 1 is started to restart the drive of the engine 1 to prevent engine stall. Yes.

  Next, the vehicle speed V and the engagement state (completely engaged state, slip state, released state) of the vehicle speed V and the lockup clutch 24 in the accelerator OFF operation region (during deceleration traveling: hereinafter sometimes referred to as coast traveling) will be described. To do.

  The deceleration slip control that causes the lock-up clutch 24 to slip in the coasting state can be performed (permitted to be performed) depending on the operating state of the engine 1 and cannot be performed (prohibited). There is a situation. For example, the cooling water temperature Tw of the engine 1 detected by the water temperature sensor 103 and the CVT oil temperature Thc detected by the CVT oil temperature sensor 108 are within a predetermined range (for example, within a range of 50 ° C. to 80 ° C.), When the actual amount of deviation of the lockup differential pressure with respect to the lockup differential pressure command value PD is within a predetermined range, the slip amount of the slip amount is small, so that the slip control during deceleration is permitted. On the other hand, when the cooling water temperature Tw or the CVT oil temperature Thc is outside the predetermined range, the actual shift amount of the lockup differential pressure increases with respect to the lockup differential pressure command value PD, and the slip amount shift amount. Therefore, execution of slip control during deceleration is prohibited.

  FIG. 5 shows a lockup clutch operation map that is referred to when the engine is in an operating state in which the execution of the slip control during deceleration is permitted. On the other hand, FIG. 6 shows a lock-up clutch operation map that is referred to when the engine is in an engine operating state in which the execution of deceleration slip control is prohibited.

  In the lockup clutch operation map shown in FIG. 5, during coasting, the lockup clutch 24 is switched in the order of the fully engaged state, the slip state, and the released state as the vehicle speed V decreases. That is, when coasting is started in a state where the vehicle speed V is higher than V1 (for example, 50 km / h) indicated by a broken line in FIG. 5, the fully engaged state is reached when the vehicle speed V decreases to V1 in FIG. Switch to the slip state. That is, the lockup differential pressure command value PD for the lockup clutch 24 is changed from the command value for completely engaging to the command value for slipping. In this slip state, when the vehicle speed V decreases to V2 (lock-up release vehicle speed) indicated by a broken line in FIG. 5, the slip state is switched to the release state. That is, the lockup differential pressure command value PD for the lockup clutch 24 is changed from the command value for setting the slip state to the command value for setting the release state. Then, the fuel cut state is released as the lockup clutch 24 is switched to the released state. That is, the fuel injection from the fuel injection device 14 is started to restart the driving of the engine 1 to prevent engine stall.

  On the other hand, in the lockup clutch operation map shown in FIG. 6, since the execution of the slip control during deceleration is prohibited as described above, coasting is started in a state where the vehicle speed V is higher than V3 indicated by the broken line in FIG. When the vehicle speed V decreases to V3 (lockup release vehicle speed) in FIG. That is, the lockup differential pressure command value PD for the lockup clutch 24 is changed from the command value for completely engaging to the command value for releasing. Then, the fuel cut state is released as the lockup clutch 24 is switched to the released state. That is, the fuel injection from the fuel injection device 14 is started to restart the driving of the engine 1 to prevent engine stall.

  The lockup release vehicle speed in the engine operation state where the slip control during deceleration is permitted (vehicle speed V2 in FIG. 5) and the lockup release vehicle speed in the engine operation state where slip control during deceleration is prohibited (in FIG. 6). It is a value different from the vehicle speed V3). The reason will be described below.

  When the deceleration slip control is permitted, when the release command signal is transmitted to the lockup clutch 24 (when the vehicle speed reaches the lockup release vehicle speed and the release command signal is transmitted), the lockup clutch 24 Is switched from the slip state to the release state, so that the release state can be achieved in a relatively short time. That is, even if the lockup release vehicle speed is set to a relatively low value, the lockup clutch 24 can be released before the engine speed reaches the stall speed. For this reason, in an engine operating state in which slip control during deceleration is permitted, the lockup release vehicle speed (vehicle speed V2 in FIG. 5) is set to a relatively low value (lockup release vehicle speed set by a lockup release vehicle speed changing operation described later). It is set to a value higher than V2 ′) so that the fuel consumption rate can be improved.

  On the other hand, when the deceleration slip control is prohibited, when a release command signal is transmitted to the lockup clutch 24 (when the vehicle speed reaches the lockup release vehicle speed and a release command signal is transmitted), Since the lock-up clutch 24 is switched from the fully engaged state to the released state, the time to reach the released state is when the above-described slip control during deceleration is permitted (when switching from the slip state to the released state). Longer than. In other words, when the slip control during deceleration is prohibited, the lockup release vehicle speed is set to the same value as that when the slip control during deceleration is permitted. There is a possibility that the engine rotational speed reaches the stall rotational speed before the engine stalls. Therefore, the lockup release vehicle speed in the engine operation state where the slip control during deceleration is prohibited (vehicle speed V3 in FIG. 6) is the lockup release vehicle speed in the engine operation state where the slip control during deceleration is permitted (in FIG. 5). It is set higher than the vehicle speed V2), and a long time is required until the engine speed reaches the stall speed so that the lockup clutch 24 can be switched to the released state before the stall speed is reached.

  As a specific example of the lockup release vehicle speeds V2 and V3, the lockup release vehicle speed (vehicle speed V3 in FIG. 6) in the engine operating state in which the deceleration slip control is prohibited is set to 20 km / h. On the other hand, the lockup release vehicle speed (vehicle speed V2 in FIG. 5) in the engine operating state in which the slip control during deceleration is permitted is set to 12 km / h. These values are not limited to this, and are appropriately set by experiment, simulation, or the like.

  By the way, in the vehicle equipped with the torque converter 2 having the lock-up clutch 24 as described above, in order to further improve the fuel consumption rate, the lock-up release vehicle speed is set lower or the lock-up clutch 24 is set. It is necessary to set the engine speed to be low during steady running when the vehicle is in a fully engaged state or slip state (during running with the accelerator pedal operation amount being constant).

  However, simply setting the lock-up release vehicle speed to a low value or setting the engine speed to a low value during steady driving will result in a sudden braking request for the vehicle (when the brake pedal is depressed greatly by the driver). Due to the fact that the lock-up clutch 24 is in the engaged state or the slip state, the engine speed rapidly decreases as the rotational speed of the drive wheels 7L and 7R rapidly decreases due to sudden braking of the vehicle. . In such a situation, the timing at which the lockup clutch 24 is released (timing at which the vehicle speed reaches the lockup release vehicle speed and the lockup clutch 24 is released and then the lockup clutch 24 is released). There is a possibility that the engine speed reaches the stall speed earlier than that, leading to an engine stall.

  Therefore, in the present embodiment, whether or not the hydraulic pressure learning of the lockup clutch 24 described later is completed (learning completion or not completed), and the control state of the lockup clutch 24 (whether the engagement state is completely engaged or slipped). According to the other, the lockup release vehicle speed and the engine speed during steady running are set appropriately. Hereinafter, the setting operation of the lockup release vehicle speed and the engine speed at the steady state will be described.

-Setting operation of lockup release vehicle speed and engine speed during steady driving-
In the operation of setting the lockup release vehicle speed in the present embodiment, when the lockup clutch 24 is switched from the fully engaged state to the released state (in the engine operation state where the slip control during deceleration is prohibited, the vehicle speed is released from the lockup release). When the vehicle speed is reached and the lock-up clutch 24 is switched from the fully engaged state to the released state), and when the lock-up clutch 24 is switched from the slip state to the released state (engine operating state where slip control during deceleration is permitted) In any case, when the vehicle speed reaches the lockup release vehicle speed and the lockup clutch 24 is switched from the slip state to the release state), the hydraulic pressure learning of the lockup clutch 24 is not completed. Lock-up clutch 24 with respect to the vehicle speed Hydraulic learning so that setting a low lock-up release vehicle speed which is set in the context have completed.

  Further, in the setting operation of the engine speed at the time of steady running in the present embodiment, the lockup is performed both when the lockup clutch 24 is in the fully engaged state and when the lockup clutch 24 is in the slip state. The engine speed during steady running set when the hydraulic pressure learning of the lockup clutch 24 is completed, compared to the engine speed during steady running set when the hydraulic pressure learning for the clutch 24 is not completed. Is set low. This will be specifically described below.

  FIG. 7 is a flowchart showing the procedure of the control operation for setting the lockup release vehicle speed and the engine speed during steady running in the present embodiment. This flowchart is executed every several msec or every predetermined rotation angle of the crankshaft after the engine 1 is started.

  First, in step ST1, the engagement state of the lockup clutch 24 is determined. That is, it is determined whether the current state of the lockup clutch 24 is in the fully engaged state, the slip state, or the released state.

  Specifically, as the determination operation, first, based on the cooling water temperature Tw of the engine 1 detected by the water temperature sensor 103, the CVT oil temperature Thc detected by the CVT oil temperature sensor 108, etc., the deceleration of the lockup clutch 24 is performed. It is determined whether the engine is in an engine operating state where execution of the hour slip control is permitted or prohibited. That is, whether the control of the engagement state of the lockup clutch 24 is performed according to the lockup clutch operation map shown in FIG. 5 or whether the control is performed according to the lockup clutch operation map shown in FIG. to decide. In addition, when the current operation state is in the accelerator ON operation region, the current lockup clutch 24 is based on the vehicle speed V detected by the vehicle speed sensor 106 and the accelerator opening Acc detected by the accelerator opening sensor 107. It is determined whether the state is in a fully engaged state, a slip state, or a released state. Further, when the current driving state is in the accelerator-off driving region, the current lock-up clutch 24 is in the fully engaged state, the slip state, or the released state based on the vehicle speed V detected by the vehicle speed sensor 106. It is determined whether it is in.

  The operation for determining the engagement state of the lockup clutch 24 is not limited to this. For example, the engagement state of the lockup clutch 24 is determined based on the deviation between the turbine speed Nt detected by the turbine speed sensor 104 and the engine speed Ne detected by the engine speed sensor 101. Also good.

  Next, the process proceeds to step ST2, and it is determined whether or not the determined state of the lockup clutch 24 is a complete engagement state. If the lock-up clutch 24 is in the fully engaged state and the determination in step ST2 is YES, the process proceeds to step ST3 to determine whether or not lock-up clutch hydraulic pressure learning (lock-up differential pressure learning) has been completed. . A specific operation for determining whether or not the oil pressure learning of the lockup clutch has been completed will be described later.

  If the lockup clutch hydraulic pressure learning has not yet been completed (and has not been completed) and the determination in step ST3 is NO, the process proceeds to step ST4, where the lockup release vehicle speed is set to V3 and Set the engine speed to Ne3. As a specific example, the lockup release vehicle speed V3 is set to 20 km / h as described above, and the engine speed Ne3 in a steady state is set to 1200 rpm.

  When each value is set in this way, for example, when the engine is in an engine operating state in which the slip control during deceleration is prohibited (an operating state in which the lockup clutch 24 is controlled according to the lockup clutch operation map shown in FIG. 6). For example, when the vehicle speed V drops to V3 (20 km / h), for example, when the vehicle is suddenly braked, a release command signal for the lockup clutch 24 is transmitted, and the lockup clutch 24 switches from the fully engaged state to the released state. Will be. Since this lock-up release vehicle speed V3 is a relatively high value, a long time is required until the engine speed reaches the stall speed (for example, 500 rpm), and the hydraulic pressure learning is not completed and the lock is temporarily set. Even if the amount of deviation of the actual lockup differential pressure is larger than the up differential pressure command value PD (even if the actual lockup differential pressure is larger than the lockup differential pressure command value PD: It is possible to switch the lockup clutch 24 to the released state before the engine speed reaches the stall speed (even if the engagement force in the fully engaged state is high).

  Further, even when a sudden braking request for the vehicle is generated during steady running, the engine speed Ne3 is a relatively high value, and therefore, from the start of the sudden braking request until the engine speed reaches the stall rotational speed. Even if the above-described hydraulic pressure learning is not completed and the amount of deviation of the actual lockup differential pressure is larger than the lockup differential pressure command value PD (lockup differential pressure command value) Even if the actual lockup differential pressure with respect to PD is large (even if the engagement force in the fully engaged state is high), the lockup clutch 24 is released before the engine speed reaches the stall speed. It is possible to switch to a state.

  In step ST3, when the hydraulic pressure learning of the lockup clutch is completed and it is determined YES, the process proceeds to step ST5, and the lockup release vehicle speed is set to the lockup release vehicle speed set when the hydraulic pressure learning is not completed. The engine speed is set to V3 ′ lower than V3 (see the lockup release vehicle speed indicated by the solid line in FIG. 6), and the engine speed at the steady state is set when the hydraulic pressure learning is not completed. Ne3 ′ is set lower than the number Ne3. As a specific example, the lockup release vehicle speed V3 'is set to 15 km / h, and the engine speed Ne3' at the normal time is set to 1100 rpm. In this way, when the engine speed Ne is set low, the gear ratio γ of the belt-type continuously variable transmission 4 is reduced in order to maintain the current vehicle speed V. For example, a map defining the relationship between the vehicle speed V, the engine speed Ne, and the gear ratio γ is stored in the ROM 82, and the engine speed Ne is set low while maintaining the current vehicle speed V (lower to Ne3 ′). The belt-type continuously variable transmission 4 is controlled so that the gear ratio γ is obtained.

  When each value is set in this way, for example, when the engine is in an engine operating state in which the slip control during deceleration is prohibited (an operating state in which the lockup clutch 24 is controlled according to the lockup clutch operation map shown in FIG. 6). For example, when the vehicle speed V decreases to V3 ′ (15 km / h), for example, when the vehicle is suddenly braked, a release command signal for the lockup clutch 24 is transmitted, and the lockup clutch 24 changes from the fully engaged state to the released state. It will be switched. The lockup release vehicle speed V3 ′ is a value set relatively low, but since the hydraulic pressure learning has already been completed and the deviation amount of the actual lockup differential pressure with respect to the lockup differential pressure command value PD is small, the vehicle speed Even if V decreases to the lockup release vehicle speed V3 ′, if the release operation of the lockup clutch 24 is started from this point, the lockup clutch 24 is switched to the released state before the engine speed reaches the stall speed. Is possible. That is, the lockup release vehicle speed can be set low without causing engine stall, and the fuel consumption rate can be greatly improved. As described above, the lockup release vehicle speed V3 ′ is set so that the engine speed becomes the stall speed if the release operation of the lockup clutch 24 is started when the vehicle speed V reaches the lockup release vehicle speed V3 ′. This value is obtained by experiment, simulation, or the like as a value that enables the lockup clutch 24 to be switched to the released state before reaching. Further, the lock-up release vehicle speed V3 ′ does not necessarily have to be a constant value, and is a value that satisfies the above condition (the release of the lock-up clutch 24 from the time when the vehicle speed V reaches the lock-up release vehicle speed V3 ′. If the operation is started, it may be a value that allows the lock-up clutch 24 to be switched to the released state before the engine speed reaches the stall speed), and is set based on the map or calculation from the engine operating state. You may do it.

  Further, even when a sudden braking request for the vehicle occurs during steady running, the hydraulic pressure learning has already been completed, and the amount of deviation of the actual lockup differential pressure with respect to the lockup differential pressure command value PD is small. If the release operation of the lock-up clutch 24 is started from the time when Ne decreases to Ne3 ′, the lock-up clutch 24 can be switched to the released state before the engine speed reaches the stall speed. That is, it is possible to set the engine speed at a normal time low without causing an engine stall, and the fuel consumption rate can be greatly improved. Note that, as described above, if the engine speed Ne3 ′ starts the releasing operation of the lock-up clutch 24 from the time when the engine speed Ne reaches the engine speed Ne3 ′, the engine speed becomes the stall speed. This value is obtained by experiment, simulation, or the like as a value that enables the lockup clutch 24 to be switched to the released state before reaching. Further, the engine speed Ne3 ′ does not necessarily have to be a constant value. The value satisfying the above condition (the engine speed Ne reaches the engine speed Ne3 ′ and the lockup clutch 24 is released). If the operation is started, it may be a value that allows the lock-up clutch 24 to be switched to the released state before the engine speed reaches the stall speed), and is set based on the map or calculation from the engine operating state. You may do it.

  If it is determined in step ST2 that the lockup clutch 24 is not completely engaged and NO is determined, the process proceeds to step ST6, and it is determined whether or not the determined state of the lockup clutch 24 is a slip state. . If the lock-up clutch 24 is in the slip state and a YES determination is made in step ST6, the process proceeds to step ST7 to determine whether or not the lock-up clutch hydraulic pressure learning has been completed.

  If the lockup clutch hydraulic pressure learning has not yet been completed (and has not been completed) and the determination in step ST7 is NO, the process proceeds to step ST8, where the lockup release vehicle speed is set to V2 and the steady state The engine speed is set to Ne2. As a specific example, the lockup release vehicle speed V2 is set to 12 km / h, and the engine speed Ne2 in a steady state is set to 1000 rpm.

  When each value is set in this way, for example, when the engine is in an engine operating state in which the deceleration slip control is permitted (an operating state in which the lockup clutch 24 is controlled according to the lockup clutch operation map shown in FIG. 5). For example, when the vehicle speed V drops to V2 (12 km / h), for example, when the vehicle is suddenly braked, a release command signal for the lockup clutch 24 is transmitted and the lockup clutch 24 is switched from the slip state to the release state. become. Since this lockup release vehicle speed V2 is a relatively high value, a long time is required until the engine speed reaches the stall speed (for example, 500 rpm), and the above-described hydraulic pressure learning is not completed and is temporarily locked. Even if the amount of deviation of the actual lockup differential pressure is larger than the up differential pressure command value PD (even if the actual lockup differential pressure is larger than the lockup differential pressure command value PD: It is possible to switch the lockup clutch 24 to the released state before the engine speed reaches the stall speed (even if the slip amount in the slip state is small).

  Further, even when a sudden braking request for the vehicle is generated during steady running, the engine speed Ne2 is a relatively high value, so that the engine speed reaches the stall rotational speed from the start of the sudden braking request. Even if the above-described hydraulic pressure learning is not completed and the amount of deviation of the actual lockup differential pressure is larger than the lockup differential pressure command value PD (lockup differential pressure command value) Even if the actual lockup differential pressure with respect to PD is large (even if the slip amount in the slip state is small), the lockup clutch 24 is released before the engine speed reaches the stall speed. It is possible to switch to

  In step ST7, when the hydraulic pressure learning of the lockup clutch is completed and YES is determined, the process proceeds to step ST9, where the lockup release vehicle speed is set to the lockup release vehicle speed set when the hydraulic pressure learning is not completed. Set to V2 ′ lower than V2 (see the lockup release vehicle speed indicated by the solid line in FIG. 5), and the steady-state engine speed is set when the hydraulic pressure learning is not completed. Ne2 ′ is set lower than the number Ne2. As a specific example, the lockup release vehicle speed V2 'is set to 10 km / h, and the engine speed Ne2' at the normal time is set to 900 rpm. Thus, even when the engine speed Ne is set low, the gear ratio γ of the belt-type continuously variable transmission 4 is reduced in order to maintain the current vehicle speed V. For example, as described above, a map defining the relationship between the vehicle speed V, the engine speed Ne, and the gear ratio γ is stored in the ROM 82, and the engine speed Ne is set low while maintaining the current vehicle speed V (see above). The belt-type continuously variable transmission 4 is controlled so as to obtain the speed ratio γ.

  When each value is set in this way, for example, when the engine is in an engine operating state in which the deceleration slip control is permitted (an operating state in which the lockup clutch 24 is controlled according to the lockup clutch operation map shown in FIG. 5). For example, when the vehicle speed V decreases to V2 ′ (10 km / h), for example, during sudden braking of the vehicle, a release command signal for the lockup clutch 24 is transmitted, and the lockup clutch 24 is switched from the slip state to the release state. It will be. The lockup release vehicle speed V2 ′ is a value set relatively low, but since the hydraulic pressure learning has already been completed and the deviation amount of the actual lockup differential pressure with respect to the lockup differential pressure command value PD is small, the vehicle speed Even if V decreases to the lockup release vehicle speed V2 ′, if the release operation of the lockup clutch 24 is started from this point, the lockup clutch 24 is switched to the released state before the engine speed reaches the stall speed. Is possible. That is, the lockup release vehicle speed can be set low without causing engine stall, and the fuel consumption rate can be greatly improved. As described above, the lockup release vehicle speed V2 ′ is set so that the engine speed becomes the stall speed if the release operation of the lockup clutch 24 is started when the vehicle speed V reaches the lockup release vehicle speed V2 ′. This value is obtained by experiment, simulation, or the like as a value that enables the lockup clutch 24 to be switched to the released state before reaching. Further, the lock-up release vehicle speed V2 ′ does not necessarily have to be a constant value, and is a value that satisfies the above condition (the release of the lock-up clutch 24 from the time when the vehicle speed V reaches the lock-up release vehicle speed V2 ′. If the operation is started, it may be a value that allows the lock-up clutch 24 to be switched to the released state before the engine speed reaches the stall speed), and is set based on the map or calculation from the engine operating state. You may do it.

  Further, even when a sudden braking request for the vehicle occurs during steady running, the hydraulic pressure learning has already been completed, and the amount of deviation of the actual lockup differential pressure with respect to the lockup differential pressure command value PD is small. If the release operation of the lock-up clutch 24 is started from the time when Ne decreases to Ne2 ′, the lock-up clutch 24 can be switched to the released state before the engine speed reaches the stall speed. That is, it is possible to set the engine speed at a normal time low without causing an engine stall, and the fuel consumption rate can be greatly improved. Note that, as described above, if the engine speed Ne2 ′ starts the releasing operation of the lockup clutch 24 when the engine speed Ne reaches the engine speed Ne2 ′, the engine speed becomes the stall speed. This value is obtained by experiment, simulation, or the like as a value that enables the lockup clutch 24 to be switched to the released state before reaching. Further, the engine speed Ne2 ′ does not necessarily have to be a constant value. The value satisfying the above condition (the engine speed Ne has reached the engine speed Ne2 ′ and the lockup clutch 24 is released). If the operation is started, it may be a value that allows the lock-up clutch 24 to be switched to the released state before the engine speed reaches the stall speed), and is set based on the map or calculation from the engine operating state. You may do it.

  FIG. 8 shows an example of the lockup release vehicle speed and the engine speed at the steady state set according to the lockup clutch engagement state and the lockup differential pressure learning state by the above procedure.

  As described above, the lockup clutch hydraulic pressure learning is completed for the lockup release vehicle speed and the steady state engine speed set when the lockup clutch 24 hydraulic pressure learning is not completed. The lockup release vehicle speed and the engine speed at the normal time are set low.

-Lockup differential pressure learning completion judgment operation-
Next, an operation procedure for determining the completion of lockup differential pressure learning will be described. First, an outline of lockup differential pressure learning (lockup clutch hydraulic pressure learning) will be described.

The lock-up differential pressure learning, during steady running (in a situation there is no large variation in the engine load) is performed. Note that the execution conditions of this lockup differential pressure learning are well known, and thus the description thereof is omitted here. The outline of this lockup differential pressure learning will be described below.

  In the conventional general lockup differential pressure learning, when a release command signal is transmitted from the fully engaged state of the lockup clutch 24 at the time of deceleration of the vehicle, the lockup clutch 24 is released from the signal transmission time point. The lockup differential pressure is learned so that the time (release time) required until the time (until the rotational difference between the turbine speed Nt and the engine speed Ne reaches a predetermined value) approximately matches the target time (release target time). Was. That is, when the release time is within the predetermined range (when the deviation is within the predetermined range with respect to the release target time), it is determined that the lockup differential pressure learning is completed.

  However, when the above-described lockup differential pressure learning is performed while the lockup clutch 24 is in the slip state, in this learning operation, the deviation between the lockup differential pressure command value PD and the actual lockup differential pressure is reduced. Therefore, there is no difference between the release time and the target release time (the learning operation is performed in a state where the actual lockup differential pressure substantially matches the nominal product by feedback control). Therefore, there is no difference between the release time and the release target time), and it is impossible to determine whether or not the lockup differential pressure learning is completed based on this time difference.

  For this reason, in this embodiment, the lockup differential pressure learning completion determination as described below is performed. Hereinafter, a case where the actual lockup differential pressure is shifted to a higher side than the lockup differential pressure instruction value PD (a case where the feedback value is obtained as a value on the pressure reduction side) will be described as a representative.

  First, the lockup differential pressure instruction value PD is lowered from a fully engaged state of the lockup clutch 24 toward a hydraulic pressure value that is lower by a predetermined pressure reduction correction amount (for example, 10 kPa in the pressure reduction direction). Even if the lockup differential pressure command value PD is set low to the predetermined pressure reduction correction amount, the rotational speed difference (slip amount) between the turbine rotational speed (turbine rotational speed) Nt and the engine rotational speed (engine rotational speed) Ne. When NSLP (= Ne−Nt) does not reach a predetermined value (for example, 10 rpm), it is determined that the actual lockup differential pressure is deviated to a higher side with respect to the lockup differential pressure instruction value PD. The learning value (for example, 5 kPa) is used to correct the lockup differential pressure command value PD to the pressure-reducing side (correction so as to lower the lockup differential pressure command value PD), and the current learning operation is terminated.

  In the next learning operation, after reflecting the learning value, the lock-up clutch 24 is locked up from the fully engaged state to the hydraulic pressure value lower by the predetermined depressurization correction amount (10 kPa) as described above. The differential pressure instruction value PD is lowered. If the slip amount NSLP still does not reach the predetermined value (10 rpm) even if the lockup differential pressure instruction value PD is set low to the predetermined pressure reduction correction amount, it is further locked up by a predetermined learning value (5 kPa). The differential pressure instruction value PD is learned and corrected to the reduced pressure side, and the current learning operation is terminated.

  As described above, in the lockup differential pressure learning, the lockup differential pressure instruction value PD is changed so that the slip amount (slip rotation speed) of the lockup clutch 24 is set to a predetermined slip amount (10 rpm in the above case). Then, when the slip amount of the lockup clutch 24 does not reach the predetermined slip amount (10 rpm), the lockup differential pressure instruction value PD is learned (learned value 5 kPa).

  The above operation is repeated until a predetermined value (10 rpm) is obtained as the slip amount NSLP until the hydraulic pressure value lower by the predetermined pressure reduction correction amount (10 kPa) is reached. In such an operation, the correction amount to the decompression side executed until the slip amount NSLP reaches a predetermined value (10 rpm) (the decompression correction amount (10 kPa when the slip amount NSLP cannot be obtained)) is set. The feedback value. That is, this feedback value becomes “10 kPa” when the slip amount NSLP does not reach the predetermined value (10 rpm) even if the lockup differential pressure instruction value PD is set low until the predetermined pressure reduction correction amount. When the slip amount NSLP reaches a predetermined value (10 rpm) before reaching “10 kPa”, the value becomes 10 kPa or less. Further, the slip amount in this learning operation becomes the actual slip rotation speed. That is, the actual slip rotation speed becomes less than 10 rpm when the slip amount NSLP does not reach the predetermined value (10 rpm) even if the lockup differential pressure instruction value PD is set low until the predetermined pressure reduction correction amount. When the slip amount NSLP reaches a predetermined value (10 rpm) before the value reaches “10 kPa”, it becomes 10 rpm.

  FIG. 9 is a flowchart showing an operation procedure of lockup differential pressure learning completion determination. First, in step ST11, the feedback value PFB and the actual slip rotation speed NSL by the lockup differential pressure learning described above are acquired.

  Thereafter, the process proceeds to step ST12, and it is determined whether or not the feedback value PFB is equal to or less than a predetermined value PFB1 (in the above case, 10 kPa or less). If the feedback value is equal to or less than the predetermined value PFB1 and YES is determined in step ST12, the process proceeds to step ST13, and the actual slip rotation speed NSL becomes the predetermined value NSL1 (10 rpm in the above case). It is determined whether or not. If the actual slip rotation speed NSL is a predetermined value NSL1 and YES is determined in step ST13, it is determined that the lockup differential pressure learning is completed by moving to step ST14. That is, the feedback value PFB is equal to or less than the predetermined value PFB1 (10 kPa) because the slip amount NSLP has reached a predetermined value (10 rpm) before the pressure reduction correction amount reaches “10 kPa”, and the actual slip rotation. It is determined that the lockup differential pressure learning is completed on condition that the number NSL is a predetermined value NSL1 (10 rpm). That is, the slip amount of the lockup clutch 24 is in the state where the feedback value for setting the slip amount (slip rotation speed) of the lockup clutch 24 to the predetermined slip amount (10 rpm) is equal to or less than the predetermined value PFB1 (10 kPa). When the predetermined slip amount (10 rpm) is reached, it is determined that the differential pressure learning of the lockup clutch 24 has been completed.

  Based on this determination, YES is determined in steps ST3 and ST7 in the flowchart shown in FIG. On the other hand, if NO is determined in step ST12 or step ST13, it is determined that the lockup differential pressure learning is not completed (not completed). Based on this determination, NO is determined in steps ST3 and ST7 in the flowchart shown in FIG.

  As described above, in the present embodiment, when the differential pressure learning of the lockup clutch 24 is completed when the lockup clutch 24 is in the fully engaged state or the slip state, the lockup release vehicle speed is reduced. The value is set low, and the value of the rotational speed of the engine 1 during steady running is set low. For this reason, it is possible to set the lockup release vehicle speed low without causing the engine 1 to stall, and it is possible to set the value of the rotational speed of the engine 1 during steady running to a low value. The consumption rate can be greatly improved.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to a vehicle equipped with a belt type continuously variable transmission (CVT) 4 as a transmission has been described. The present invention is not limited to this, and can also be applied to a vehicle equipped with a planetary gear type transmission.

  In the above embodiment, the case where the present invention is applied to an FF (front engine / front drive) vehicle has been described. However, the present invention is also applied to an FR (front engine / rear drive) vehicle or a four-wheel drive vehicle. Is applicable.

  In the above-described embodiment, the case where the present invention is applied to an automobile equipped with the gasoline engine 1 has been described. The present invention is not limited to this, and can also be applied to an automobile equipped with a diesel engine. Further, the number of cylinders and the engine type (V type, horizontally opposed type, etc.) are not particularly limited.

The present invention is, with respect to a vehicle equipped with a torque converter with a lock-up clutch, it is applicable to control for improving the fuel consumption rate due to the set lower engine speed during steady running.

1 Engine (drive source)
24 Lock-up clutches V2, V2 ', V3, V3' Lock-up release vehicle speeds Ne2, Ne2 ', Ne3, Ne3' Engine speed during steady running

Claims (2)

In a vehicle control device in which a lock-up clutch capable of switching between a fully engaged state, a slip state, and a released state is disposed on a driving force transmission path from a driving source to a driving wheel.
The lockup differential pressure instruction value is changed so that the slip rotation speed of the lockup clutch is a predetermined slip rotation speed. Even if the lockup differential pressure instruction value becomes a predetermined value, the slip rotation speed of the lockup clutch is When the predetermined slip rotation speed is not reached, a learning operation for learning and correcting the lockup differential pressure instruction value by a predetermined learning value is performed, and feedback for setting the slip rotation speed of the lockup clutch to the predetermined slip rotation speed If the slip rotation speed of the lockup clutch does not reach the predetermined slip rotation speed even if the value reaches the predetermined value, the differential pressure learning of the lockup clutch is incomplete, and the feedback value is below the predetermined value When the slip rotation speed of the lockup clutch reaches the predetermined slip rotation speed in this state, the lockup clutch While it is determined that the differential pressure learning of the pitch has been completed,
When the lock-up clutch is in a fully engaged state or slip state, and when the differential pressure learning of the lock-up clutch is not completed during steady running where the accelerator pedal is depressed and the operation amount is constant, Compared to the case where the pressure learning is completed, the amount of deviation of the actual engagement pressure relative to the engagement pressure command value of the lockup clutch is large. In order to ensure a long time from the start of the sudden braking request until the rotational speed of the drive source reaches the stall rotational speed, the actual engagement pressure is shifted to the higher side with respect to the engagement pressure instruction value of the lockup clutch. Even if the rotational speed of the drive source reaches the stall rotational speed, set the rotational speed of the drive source so that the lockup clutch can be switched to the released state,
When the lock-up clutch is in a fully engaged state or slip state, and when the differential pressure learning of the lock-up clutch is completed during steady running where the accelerator pedal is depressed and the operation amount is constant, Even if a sudden braking request for the vehicle occurs during the steady running, the driving source is assumed that the amount of deviation of the actual engagement pressure from the engagement pressure command value of the lockup clutch is small compared with the case where the differential pressure learning is not completed. A drive source that is capable of switching the lock-up clutch to the disengaged state before reaching the stall rpm, and lower than the drive source rpm when the differential pressure learning is not completed. Set to the number of revolutions
When the value of the rotational speed of the drive source is set to a low value in accordance with the completion of the differential pressure learning of the lockup clutch during the steady running when the lockup clutch is in the fully engaged state or the slip state, A configuration in which a transmission gear ratio for maintaining the current vehicle speed is obtained as a value smaller than a transmission gear ratio when differential pressure learning is not completed, and the transmission is controlled so that the obtained transmission gear ratio is obtained. A control apparatus for a vehicle, characterized in that The vehicle control device according to claim 1,
During the steady running set when the lockup clutch is in a slip state with respect to the value of the rotational speed of the drive source during the steady running set when the lockup clutch is in a fully engaged state The vehicle control device is characterized in that the value of the rotational speed of the drive source at is set low.

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