JP2019032003A - Vehicle controller - Google Patents

Abstract

To provide a vehicle controller capable of improving learning accuracy upon learning a reference value of lock-up pressure Plu.SOLUTION: During fastening of a lock-up clutch 20 included in a torque converter 2 arranged between an engine 1 and a drive wheel 9, when a vehicle is in a state where a foot is not on an accelerator pedal, a forward clutch 31 arranged between the torque converter 2 and the drive wheel 9 is let out, thereby reducing a fastening capacity of the lock-up clutch 20. Here, lock-up pressure Plu (reference value) is learned, wherein the lock-up pressure is supply oil pressure to the lock-up clutch 20 at the time when the rotational difference between an engine speed of an engine output shaft 11 and an engine speed of a torque converter output shaft 21 becomes a predetermined value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle control apparatus that performs oil pressure learning of a lockup clutch included in a torque converter.

  Conventionally, when the vehicle starts coasting while the lockup clutch of the torque converter is engaged, the engagement capacity of the lockup clutch (hereinafter referred to as “lockup capacity”) is gradually decreased, and the slip in the lockup clutch is reduced. 2. Description of the Related Art A vehicle control device that learns a hydraulic pressure supplied to a lockup clutch (hereinafter referred to as “lockup pressure”) based on rotation is known (see, for example, Patent Document 1).

JP 2008-008321 A

  However, there is room for improvement in learning of the lock-up pressure in the conventional vehicle control device. In other words, the lockup clutch has a driving power source such as an engine connected to the driving force input side and driving wheels connected to the driving force output side. For this reason, when learning the lockup pressure, torque input from the drive force input side and torque input from the drive force output side are generated in the lockup clutch. As a result, it is difficult to detect a lockup pressure (hereinafter referred to as “reference value”) when the lockup capacity is generated and when the lockup capacity is not generated.

  Further, in the vehicle control device described in Patent Document 1, since the lockup pressure is learned during coasting, the torque input from the input side and the output side of the lockup clutch is low. However, since the torque input is not zero, the reference value varies according to the input torque. Therefore, when the input torque is different, the actual reference value is different from the learned reference value.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle control device that can improve the learning accuracy when learning the reference value of the lockup pressure.

In order to achieve the above object, a vehicle control device of the present invention includes a travel drive source, a torque converter disposed between the travel drive source and the drive wheels, a lockup clutch included in the torque converter, a torque converter and a drive. The lock-up pressure, which is the hydraulic pressure supplied to the lock-up clutch when the rotational difference between the frictional engagement element arranged between the wheels and the input rotational speed of the torque converter and the output rotational speed of the torque converter reaches a predetermined value, A learning control unit for learning.
The learning control unit learns the lockup pressure by releasing the frictional engagement element and lowering the engagement capacity of the lockup clutch when traveling with the accelerator released while the lockup clutch is engaged. .

  Therefore, in the present invention, it is possible to improve the learning accuracy when learning the reference value of the lockup pressure.

1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which a vehicle control device of Example 1 is applied. It is a flowchart which shows the flow of the lockup pressure learning process performed with the CVT control unit of Example 1. FIG. It is explanatory drawing explaining the input torque to a torque converter when learning lockup pressure in the vehicle control apparatus of a comparative example. In the vehicle control apparatus according to the first embodiment, the accelerator opening, idle switch, vehicle speed, engine torque, forward clutch pressure, turbine torque, lockup pressure, engine speed, and turbine speed when learning the lockup pressure It is a time chart which shows. It is explanatory drawing explaining the input torque to a torque converter when learning lockup pressure in the vehicle control apparatus of Example 1. FIG. It is a whole system figure which shows the engine vehicle to which the vehicle control apparatus of Example 2 was applied. It is a flowchart which shows the flow of the lockup pressure learning process performed with the CVT control unit of Example 2. FIG.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the vehicle control apparatus of this invention is demonstrated based on Example 1 and Example 2 which are shown in drawing.

Example 1
First, the configuration will be described.
The vehicle control device according to the first embodiment is applied to an engine vehicle A equipped with a torque converter 2 having a lock-up clutch 20 that directly connects the engine output shaft 11 and the torque converter output shaft 21 when fastened. Hereinafter, the configuration of the first embodiment will be described by dividing it into “engine vehicle drive system configuration”, “engine vehicle control system configuration”, and “lockup pressure learning control processing configuration”.

[Drive system configuration of engine car]
FIG. 1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which the vehicle control device of the first embodiment is applied. Hereinafter, the drive system configuration of the engine vehicle A according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 1, the drive system of the engine vehicle A to which the vehicle control device of the first embodiment is applied includes an engine 1 that is a travel drive source, a torque converter 2, a forward / reverse switching mechanism 3, and a variator 4. The final reduction mechanism 5 and the drive wheels 9 and 9 are provided.

The engine 1 can perform coast torque control and fuel cut control in addition to output torque control by accelerator operation by a driver. The coast torque control is a control for controlling the output torque of the engine 1 to the coast torque during coast running, which is running with the accelerator released. Here, the “coast torque” is a torque that maintains the engine 1 at the idling speed.
The fuel cut control is a control for stopping the fuel supply to the engine 1 when a learning end signal of the lockup pressure Pl is input. The engine 1 includes a fuel control actuator 10 that controls fuel supply to the engine 1.

The torque converter 2 includes a pump impeller 23, a turbine runner 24 disposed to face the pump impeller 23, and a stator 26 disposed between the pump impeller 23 and the turbine runner 24. The torque converter 2 is a fluid coupling that transmits torque by circulating hydraulic oil filled therein through the blades of the pump impeller 23, the turbine runner 24, and the stator 26. Here, the pump impeller 23 is connected to the engine output shaft 11 (= torque converter input shaft) via the converter housing 22. The turbine runner 24 is connected to the torque converter output shaft 21. The stator 26 is provided in a stationary member (transmission case or the like) case via a one-way clutch 25.
Further, the torque converter 2 has a lock-up clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21.

  The lockup clutch 20 is built in the torque converter 2 and connects the engine 1 and the variator 4 via the torque converter 2 and the forward / reverse switching mechanism 3 by releasing the clutch. Further, when the torque increasing function of the torque converter 2 is not required, the lockup clutch 20 is engaged, and the engine output shaft 11 and the torque converter output shaft 21 are directly connected. When a lock-up command hydraulic pressure (hereinafter referred to as LU command hydraulic pressure) is output from the CVT control unit 7 described later, the lock-up clutch 20 adjusts the lock-up pressure Pl adjusted based on the line pressure PL that is the original pressure. Thus, the fastening / slip fastening / release is controlled. That is, this lockup pressure Pl becomes the hydraulic pressure supplied to the lockup clutch 20.

  The forward / reverse switching mechanism 3 is a mechanism that switches an input rotation direction to the variator 4 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. The forward / reverse switching mechanism 3 includes a double pinion planetary gear 30, a forward clutch 31 (friction engagement element), and a reverse brake 32 (friction engagement element). When the shift lever is in the D range position, the forward clutch 31 is fastened by pressing a plurality of clutch plates with the forward clutch pressure Pfc. The reverse brake 32 is fastened by pressing a plurality of clutch plates with the reverse brake pressure Prb when the shift lever is in the R range position. Note that both the forward clutch 31 and the reverse brake 32 are released when the shift lever is in the N range position.

  The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44. The variator 4 has a continuously variable transmission function that continuously changes a transmission gear ratio (ratio of variator input rotation speed to variator output rotation speed) by changing a belt contact diameter. The primary pulley 42 includes a first fixed pulley 42 a and a first slide pulley 42 b that are arranged coaxially with the variator input shaft 40. The first slide pulley 42b is slid by the primary pressure Ppri guided to the primary pressure chamber 45. The secondary pulley 43 includes a second fixed pulley 43a and a second slide pulley 43b that are arranged coaxially with the variator output shaft 41. The second slide pulley 43 b is slid by the secondary pressure Psec guided to the secondary pressure chamber 46. The pulley belt 44 is stretched between a sheave surface that forms a V shape of the primary pulley 42 and a sheave surface that forms a V shape of the secondary pulley 43. The pulley belt 44 is composed of two sets of stacked rings in which a large number of annular rings are stacked from the inside to the outside, and a large number of elements that are sandwiched along the two sets of stacked rings and stacked in a ring shape. Yes. The pulley belt 44 may be a chain-type belt in which a large number of chain elements arranged in the pulley traveling direction are coupled by pins penetrating in the pulley axial direction.

  The final deceleration mechanism 5 is a mechanism that decelerates the variator output rotation speed from the variator output shaft 41 and transmits it to the left and right drive wheels 9 and 9 by providing a differential function. The final reduction mechanism 5 is provided as a reduction gear mechanism at the outer peripheral position of the first gear 52 provided on the variator output shaft 41, the second gear 53 and the third gear 54 provided on the idler shaft 50, and the differential case. And a fourth gear 55. The differential gear mechanism includes a differential gear 56 interposed between the left and right drive shafts 51, 51.

[Engine vehicle control system configuration]
Hereinafter, the control system configuration of the engine vehicle A according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 1, the control system of the engine vehicle A includes a hydraulic control unit 6 that is a hydraulic control system, a CVT control unit 7 (learning control unit, CVTCU) that is an electronic control system, and an engine control unit 8 (ECU). ) And.

  The hydraulic control unit 6 includes a hydraulic source control valve 60 and a transmission control valve 61.

  The hydraulic pressure source control valve 60 selects one of the oil discharged from the mechanical oil pump 67 driven to rotate by the engine 1 and the oil discharged from the electric oil pump 69 driven to rotate by the electric motor 68 as the hydraulic pressure source. Here, during engine operation in which the engine 1 is driven to rotate, the oil discharged from the mechanical oil pump 67 is selected as a hydraulic pressure source. Further, when the engine 1 is stopped and the discharge oil from the mechanical oil pump 67 is insufficient, the discharge oil from the electric oil pump 69 is selected.

  Here, the mechanical oil pump 67 is provided on the engine output shaft 11 via a chain belt, a sprocket, or the like. The electric oil pump 69 is integrally fixed to the hydraulic source control valve 60 together with the electric motor 68. The hydraulic source control valve 60 is fixed with respect to the transmission control valve 61.

  The transmission control valve 61 adjusts various transmission control pressures based on the discharge pressure from the hydraulic source control valve 60. The pressure regulating valve includes a line pressure solenoid valve 62, a primary pressure solenoid valve 63, a secondary pressure solenoid valve 64, a clutch / brake pressure solenoid valve 65, and a lockup pressure solenoid valve 66.

  The line pressure solenoid valve 62 adjusts the discharge pressure from the hydraulic source control valve 60 to the commanded line pressure PL in accordance with the line pressure command value output from the CVT control unit 7. The line pressure PL is an original pressure when adjusting various transmission control pressures, and is a hydraulic pressure that suppresses belt slip and clutch slip with respect to transmission torque of the drive system.

  The primary pressure solenoid valve 63 regulates the primary pressure Ppri supplied to the primary pressure chamber 45. The secondary pressure solenoid valve 64 regulates the secondary pressure Psec supplied to the secondary pressure chamber 46. The clutch / brake pressure solenoid valve 65 regulates the forward clutch pressure Pfc supplied to the forward clutch 31 and the reverse brake pressure Prb supplied to the reverse brake 32. The lockup pressure solenoid valve 66 regulates the lockup pressure Pl supplied to the lockup clutch 20. Each solenoid valve 62, 63, 64, 65, 66 is regulated by a command value output from the CVT control unit 7.

  That is, in the first embodiment, the transmission control valve 61 and the solenoid valves 62, 63, 64, 65, 66 constitute a main control valve unit. The hydraulic source control valve 60, the electric motor 68, and the electric oil pump 69 constitute a sub control valve unit that is fixed to the main control valve unit.

The CVT control unit 7 performs line pressure control, shift control of the variator 4, forward / reverse switching control of the forward / reverse switching mechanism 3, lockup control of the lockup clutch 20, and lockup pressure learning control.
In the line pressure control, a line pressure command value for obtaining a target line pressure determined according to the throttle valve opening degree is output to the line pressure solenoid valve 62. In the shift control, first, a target gear ratio (target primary rotational speed Npri ^* ) is determined. Then, a hydraulic pressure command value for obtaining the determined target gear ratio is output to the primary pressure solenoid valve 63 and the secondary pressure solenoid valve 64. In the forward / reverse switching control, when the shift lever is in the D range position, a command value for engaging the forward clutch 31 is output to the clutch / brake pressure solenoid valve 65. When the shift lever is in the R range position, a command value for engaging the reverse brake 32 is output to the clutch / brake pressure solenoid valve 65. In the lock-up control, when a predetermined condition is satisfied, a command value for engaging / slipping / releasing the lock-up clutch 20 is output to the lock-up pressure solenoid valve 66.

Further, in the lockup pressure learning control, first, when coasting is started while the lockup clutch 20 is engaged, the forward clutch 31 or the reverse brake 32 of the forward / reverse switching mechanism 3 is released. Next, the lockup capacity that is the engagement capacity of the lockup clutch 20 is gradually reduced. Then, the lockup is performed when the difference between the rotational speed of the engine output shaft 11 that is the input rotational speed of the torque converter 2 and the rotational speed of the torque converter output shaft 21 that is the output rotational speed of the torque converter 2 becomes a predetermined value. The pressure Pl is learned as a “reference value” and set to a reference value for controlling the lock-up clutch 20.
The “reference value” means that when the lockup clutch 20 being engaged is released, the engagement capacity (lockup capacity) is generated in the lockup clutch 20 and the engagement capacity (lockup capacity) is generated. This is the lockup pressure Pl when the state is not switched.

  The CVT control unit 7 includes a turbine speed sensor 70, a vehicle speed sensor 71, a secondary pressure sensor 72, a clutch pressure sensor 73, an inhibitor switch 74, a brake switch 75, a front / rear G sensor 76, an idle switch 77, a primary pressure sensor 78, an accelerator. Sensor information and switch information from the opening sensor 79 and the like are input. Further, sensor information from the engine speed sensor 80 input to the engine control unit 8 is input to the CVT control unit 7 via a CAN communication line (not shown).

  The clutch pressure sensor 73 is a sensor that detects a clutch pressure (forward clutch pressure Pfc or reverse brake pressure Prb) supplied to the forward clutch 31 or the reverse brake 32. The inhibitor switch 74 detects the range position (D range position, N range position, R range position, etc.) selected by the shift lever, and outputs a range position signal corresponding to the selected range position. The idle switch 77 is a switch that detects the depression state of the accelerator pedal. The idle switch 77 is turned off when the accelerator pedal is depressed, and is turned on when the accelerator pedal is not depressed (when the accelerator is released). The accelerator opening sensor 79 is a sensor that detects the amount of depression of the accelerator pedal (accelerator opening). Here, the accelerator opening becomes higher as the accelerator pedal is depressed.

  The engine control unit 8 is a controller that controls the engine 1. Information from the engine speed sensor 80 is input to the engine control unit 8. Further, the engine control unit 8 stops the fuel supply to the engine 1 when the learning end signal of the lockup pressure Pl is inputted.

[Lockup pressure learning control processing configuration]
FIG. 2 is a flowchart showing the flow of the lockup pressure learning control process executed by the CVT control unit of the first embodiment. Hereinafter, based on FIG. 2, the lockup pressure learning control processing configuration of the first embodiment will be described. Note that this lockup pressure learning control process is continuously executed during traveling (while the vehicle speed is generated).

In step S1, it is determined whether or not the lockup clutch 20 is in an engaged state. If YES (lockup engagement), the process proceeds to step S2. If NO (lockup release), proceed to return.
Here, whether or not the lock-up clutch 20 is in the engaged state is detected by the rotational speed of the engine output shaft 11 (torque converter input rotational speed) detected by the engine rotational speed sensor 80 and the turbine rotational speed sensor 70. This is determined based on whether or not the differential rotation (hereinafter referred to as “torque converter differential rotation”) with respect to the rotational speed of the torque converter output shaft 21 (torque converter output rotational speed) is zero.
The lockup clutch 20 is determined to be engaged (completely engaged) when the torque converter differential rotation is within a range where it can be determined to be “zero”.

In step S2, following the determination of lock-up engagement in step S1, it is determined whether or not the operation state of the accelerator pedal is an accelerator release state. If YES (accelerator release), the process proceeds to step S3. In the case of NO (accelerator depression), the process proceeds to return.
Here, whether or not the accelerator is in the released state is determined based on the accelerator opening information detected by the accelerator opening sensor 79 and the switch information from the idle switch 77. The operation state of the accelerator pedal is determined to be the accelerator release state when the accelerator opening is zero and the idle switch 77 is in the ON state.

In step S3, following the determination that the accelerator is released in step S2, it is determined whether the vehicle speed is equal to or lower than a predetermined vehicle speed set in advance. If YES (vehicle speed ≦ predetermined vehicle speed), the process proceeds to step S4. If NO (vehicle speed> predetermined vehicle speed), the process proceeds to return.
Here, the “predetermined vehicle speed” is a vehicle speed at which the rotational inertia force on the input side and the output side in the lock-up clutch 20 becomes weak, and input / output differential rotation can be generated when the clutch is released. That is, even if the lockup clutch 20 is released in a state where the vehicle speed is high and the rotational inertia force is strong, the output-side rotation does not decrease due to the inertial force at the clutch release timing, and input / output differential rotation does not occur. . Therefore, the “predetermined vehicle speed” is set to a vehicle speed at which it can be determined that the rotational inertia force acting on the lockup clutch 20 does not affect the occurrence of the differential rotation. Here, for example, during coasting, which is traveling in the state where the accelerator is released, the minimum vehicle speed (about 50 km / h) when the target gear ratio of the variator 4 becomes the highest gear ratio is set.

In step S4, following the determination of vehicle speed ≦ predetermined vehicle speed in step S3, it is determined whether or not the engine torque is stable. If YES (engine torque = stable), the process proceeds to step S5. If NO (engine torque = unstable), proceed to return.
Here, the engine torque is estimated by the engine control unit 8 based on the vehicle speed. The CVT control unit 7 outputs an engine torque request to the engine control unit 8 as necessary, and acquires engine torque information from the engine control unit 8.
In addition, “engine torque is stable” means that the fluctuation of the engine torque is within a predetermined fluctuation range. Here, it is determined that the engine torque has started to decrease with the occurrence of the accelerator release. Then, it is assumed that a decrease time during which the engine torque decreases within a predetermined fluctuation range has continued for a predetermined time. That is, it is determined that the engine torque is stable when the engine torque continuously decreases for a predetermined time with a predetermined decrease gradient.

In step S5, following the determination that engine torque = stable in step S4, the friction engagement element being engaged in the forward / reverse switching mechanism 3 is released, and the process proceeds to step S6.
Here, the “friction engagement element” is the forward clutch 31 when the shift lever is in the D range position, and decreases the forward clutch pressure Pfc. The “friction engagement element” is the reverse brake 32 when the shift lever is in the R range position, and decreases the reverse brake pressure Prb.
At this time, the decreasing gradient of the forward clutch pressure Pfc (or the reverse brake pressure Prb) to be decreased is set in advance by experiments or the like so as to satisfy the release shock and the target release time. That is, the release speed of the frictional engagement element is set to a level that does not cause a release shock.

In step S6, following the release of the frictional engagement element in step S5, it is determined whether or not the elapsed time from the start of release of the frictional engagement element is equal to or greater than a preset first threshold time. If YES (elapsed time ≧ first threshold time), the process proceeds to step S7. If NO (elapsed time <first threshold time), the process returns to step S5.
Here, the “first threshold time” is a time during which it can be determined that the release of the frictional engagement element that has been released in step S5 has been completed, and is set based on an experiment or the like. Note that “completion of release of the frictional engagement element” means that the torque transmission capacity in the frictional engagement element becomes zero.

In step S7, following the determination that elapsed time ≧ first threshold time in step S6, assuming that the release of the frictional engagement element is completed and the turbine torque has stabilized, the lockup capacity, which is the engagement capacity of the lockup clutch 20, is set. Decrease and proceed to step S8.
Here, “turbine torque” is disturbance torque input from the drive wheel 9 side to the torque converter output shaft 21 of the torque converter 2. In order to decrease the lockup capacity, a command value for decreasing the lockup pressure Pl supplied to the lockup clutch 20 is output to the lockup pressure solenoid valve 66.

In step S8, following the decrease in the lockup capacity in step S7, it is determined whether or not the torque converter differential rotation caused by the decrease in the lockup capacity is equal to or greater than a preset first threshold differential rotation. If YES (first threshold differential rotation ≦ torque converter differential rotation), the process proceeds to step S9. If NO (torque converter differential rotation <first threshold differential rotation), the process returns to step S7.
Here, the first threshold difference rotation is a torque converter differential rotation when the state where the lockup capacity is generated and the state where the lockup capacity is not generated are switched.
That is, if the torque converter differential rotation is less than the first threshold differential rotation, the lockup clutch 20 is engaged (slip engagement), and if the torque converter differential rotation is greater than or equal to the first threshold differential rotation, the lockup clutch 20 is engaged. It can be determined that 20 has been released.

In step S9, following the determination of first threshold differential rotation ≦ torque converter differential rotation in step S8, the lockup capacity is adjusted up or down, and the process proceeds to step S10.
Here, “adjustment adjustment of the lockup capacity” is to control the lockup pressure Pl so that the torque converter differential rotation is kept within a certain range (between the first threshold rotation speed and the second threshold rotation speed). It is.

In step S10, following the adjustment of the lockup capacity in step S9, it is determined whether or not the torque converter differential rotation is equal to or greater than the first threshold differential rotation and equal to or smaller than the preset second threshold differential rotation. To do. If YES (first threshold differential rotation ≦ torque converter differential rotation ≦ second threshold differential rotation), the process proceeds to step S11. If NO (first threshold differential rotation> torque converter differential rotation or torque converter differential rotation> second threshold differential rotation), the process returns to step S9.
Here, the “second threshold differential rotation” is a torque converter when the lockup pressure Pl becomes lower than a value when the lockup capacity is generated and the lockup capacity is not switched. Differential rotation.

In step S11, following the determination of first threshold differential rotation ≦ torque converter differential rotation ≦ second threshold differential rotation in step S10, an elapsed time from when the differential rotation condition in step S10 is satisfied is set in advance. It is determined whether or not two threshold times or more. If YES (elapsed time ≧ second threshold time), the process proceeds to step S11. If NO (elapsed time <second threshold time), the process returns to step S9.
Here, the second threshold time is a time during which it can be determined that the lock-up pressure Pl that establishes the differential rotation condition is stable, and is set based on an experiment or the like.

In step S12, following the determination that elapsed time ≧ second threshold time in step S11, the lockup pressure Plu (reference) when the state where the lockup capacity is generated and the state where the lockup capacity is not generated is switched. Value) is set, the lock-up pressure Pl at the timing when the elapsed time after the differential rotation condition is satisfied reaches the second threshold time is set to a new “reference value”, and this “reference value” is updated. Then, the process proceeds to step S13.
The “reference value” is written in a memory (not shown) included in the CVT control unit 7.

In step S13, following the update of the “reference value” in step S12, assuming that learning of the lockup pressure Pl has been completed, a learning end signal is output, and the process proceeds to step S14.
This learning end signal is input to the engine control unit 8.

In step S14, following the output of the learning end signal in step S13, fuel cut control for stopping fuel supply to the engine 1 is executed, and the process proceeds to step S15.
Here, the fuel cut control is executed by outputting a stop signal from the engine control unit 8 to the fuel control actuator 10.

In step S15, following execution of the fuel cut control in step S14, the frictional engagement element (forward clutch 31 or reverse brake 32) released in step S5 is engaged, and the process proceeds to step S16.
Here, when the forward clutch 31 is engaged, the forward clutch pressure Pfc is increased. Further, when the reverse brake 32 is engaged, the reverse brake pressure Prb is increased. At this time, the rising gradient of the forward clutch pressure Pfc (or the reverse brake pressure Prb) is set so as to satisfy the target engagement time, but is more sudden than the decreasing gradient when the forward clutch 31 or the reverse brake 32 is released. Is set to the value That is, the fastening speed at the time of re-engagement of the frictional engagement element is set to a speed faster than the release speed, and is fastened in a shorter time than the time required for release.

In step S16, following the engagement of the frictional engagement element in step S15, it is determined whether or not the elapsed time from the start of engagement of the frictional engagement element is equal to or greater than a preset third threshold time. If YES (elapsed time ≧ third threshold time), the process proceeds to step S17. If NO (elapsed time <third threshold time), the process returns to step S15.
Here, the “third threshold time” is a time during which it can be determined that the engagement of the frictional engagement element that has been engaged in step S15 has been completed, and is set based on an experiment or the like.

In step S17, following the determination that elapsed time ≧ third threshold time in step S16, the lockup clutch 20 is engaged and the process proceeds to return.
Here, in order to engage the lockup clutch 20, the lockup capacity is increased. That is, a command value for increasing the lockup pressure Pl supplied to the lockup clutch 20 is output to the lockup pressure solenoid valve 66.

Next, the operation will be described.
First, the learning control of the lockup pressure in the vehicle control device of the comparative example and its problem will be described. Subsequently, the operation in the vehicle control device of the first embodiment is referred to as “lockup pressure learning operation”, “occupant discomfort during learning” The description will be divided into “preventive action” and “other characteristic actions”.

[Learning Control of Lock-up Pressure in Vehicle Control Device of Comparative Example and its Problem]
FIG. 3 is an explanatory diagram for explaining the input torque to the torque converter when learning the lockup pressure in the vehicle control device of the comparative example. Hereinafter, the learning control of the lock-up pressure in the vehicle control device of the comparative example of the comparative example and the problem will be described.

  Similar to the first embodiment, the vehicle B on which the vehicle control device of the comparative example is mounted has an engine 1, which is a travel drive source, a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, a drive wheel 9, 9. A final deceleration mechanism is also provided, but is omitted here.

  In the vehicle B, when the engine 1 is driven, the engine output shaft 11 rotates. A pump impeller 23 of the torque converter 2 is connected to the engine output shaft 11 via a converter housing 22. Therefore, the pump impeller 23 rotates with the rotation of the engine output shaft 11. Then, the rotation of the pump impeller 23 is transmitted to the turbine runner 24 via the hydraulic oil filled in the torque converter 2, and the turbine runner 24 rotates. A torque converter output shaft 21 is connected to the turbine runner 24. Therefore, rotation is transmitted to the forward / reverse switching mechanism 3 via the torque converter output shaft 21. In FIG. 3, 26 is a stator and 27 is a stationary member.

  On the other hand, when a predetermined lockup condition is established, the lockup clutch 20 built in the torque converter 2 is engaged. When the lockup clutch 20 is engaged, the engine output shaft 11 and the torque converter output shaft 21 are directly connected.

Similarly to the first embodiment, the forward / reverse switching mechanism 3 is engaged when the shift lever is in the D range position and the forward clutch 31 (friction engagement element) is engaged when the shift lever is in the R range position. Reverse brake 32 (friction engagement element).
When either the forward clutch 31 or the reverse brake 32 is engaged (in FIG. 3, the forward clutch 31 is engaged), the rotation transmitted to the forward / reverse switching mechanism 3 is the variator 4. Enter. Then, the rotation input to the variator 4 is transmitted to the drive wheels 9 through a speed change in the variator 4.

  In such a vehicle control device mounted on the vehicle B, the lockup pressure (reference value) when the lockup capacity is generated and when the lockup capacity is not generated is detected and learned. Explain the case.

  That is, when the vehicle B starts coasting while the lockup clutch 20 is engaged, the lockup pressure Pl is reduced and the lockup capacity is reduced. Then, the lockup is performed when the rotational difference between the input rotational speed of the torque converter 2 (the rotational speed of the engine output shaft 11) and the output rotational speed of the torque converter 2 (the rotational speed of the torque converter output shaft 21) becomes a predetermined value. The pressure Pl is set as a “reference value”.

  At this time, the engine torque from the engine 1 is input to the lock-up clutch 20 of the torque converter 2 via the engine output shaft 11 and the converter housing 22. The disturbance torque from the drive wheel 9 is input to the lockup clutch 20 through the drive wheel 9 → the variator 4 → the engaging element (forward clutch 31) of the forward / reverse switching mechanism 3 → the torque converter output shaft 21 in this order. The

  Therefore, when learning the lockup pressure Plu, the engine torque and the disturbance torque are low because of the coasting state, but the lockup clutch 20 has an input torque (engine torque) from the upstream and a downstream. The input torque (disturbance torque) from is input.

  Therefore, in a scene where the torque input to the lockup clutch 20 is different, there is a problem that the actual reference value is different from the learned reference value.

[Lock-up pressure learning action]
FIG. 4 shows the characteristics of the accelerator opening, the idle switch, the vehicle speed, the engine torque, the forward clutch pressure, the turbine torque, the engine speed, and the turbine speed when learning the lockup pressure in the vehicle control apparatus of the first embodiment. FIG. 5 is an explanatory diagram for explaining the input torque to the torque converter when learning the lockup pressure in the vehicle control apparatus of the first embodiment. Hereinafter, based on FIG.4 and FIG.5, the lockup pressure learning effect | action of Example 1 is demonstrated.

  In the engine vehicle A according to the first embodiment, the reference value (the rotational speed of the engine output shaft 11 that is the input rotational speed of the torque converter 2 and the torque converter output shaft 21 that is the output rotational speed of the torque converter 2 of the lockup clutch 20. The case of learning the “lock-up pressure Plu when the rotation difference between and a predetermined value” is learned will be described.

First, it is determined whether or not the lockup clutch 20 built in the torque converter 2 is engaged. In the case shown in FIG. 4, the engine speed and the turbine speed are the same before time t1.
Here, the “engine speed” is the speed of the engine output shaft 11 (torque converter input speed). The “turbine rotational speed” is the rotational speed of the torque converter output shaft 21 (torque converter output rotational speed). Therefore, at the time t1 shown in FIG. 4, the torque converter differential rotation is zero, and it is determined that the lockup clutch 20 is engaged. Accordingly, the process proceeds from step S1 to step S2 in the flowchart shown in FIG.

  Then, when the accelerator opening starts decreasing from time t1, and the idle switch is turned on at time t2, it is determined that the accelerator is in a released state. Furthermore, at time t3, when the vehicle speed reaches a predetermined vehicle speed or less, the process proceeds from step S2 to step S3 to step S4, and a decrease gradient of the engine torque is detected. Thereby, the stable state of the engine torque is determined.

  If it is determined at time t4 that the engine torque decreases within a predetermined fluctuation range for a predetermined time, the process proceeds from step S4 to step S5, and the forward clutch 31 being engaged is released. That is, the forward clutch pressure Pfc starts to decrease.

Here, the engine torque continues to decrease and reaches the coast torque at time t5. As a result, the engine speed and the turbine speed are maintained at the idle speed.
Here, the “coast torque” is a torque that maintains the engine speed at the idle speed in order to prevent the engine 1 from stalling, and is extremely small (for example, about 1 to 2 Nm).

  When the first threshold time elapses from time t4 when the decrease of the forward clutch pressure Pfc starts at time t6, it is determined that the release of the forward clutch pressure Pfc is completed, the process proceeds from step S6 to step S7, and the lockup capacity Begins to decline. That is, the reduction of the lockup pressure Pl starts. Thereby, learning of the “reference value” of the lock-up pressure Pl is started.

  As the lockup capacity decreases, a difference occurs between the engine speed and the turbine speed from time t7, and the torque converter differential rotation Δx begins to increase.

  Thereafter, when the torque converter differential rotation reaches or exceeds the first threshold differential rotation at time t8, the process proceeds from step S8 to step S9, and the decrease in the lockup pressure Pl is stopped. Then, the lockup pressure Pl is controlled so that the torque converter differential rotation Δx falls within a certain range (between the first threshold rotation speed and the second threshold rotation speed), and the lockup capacity is adjusted.

At time t9, when the torque converter differential rotation Δx falls within a certain range (between the first threshold rotational speed and the second threshold rotational speed) and the second threshold time elapses after the differential rotational condition is satisfied, the differential rotational speed is reached. Assuming that the lock-up pressure Pl that establishes the condition is stable, the process proceeds from step S10 to step S11 to step S12. Then, the lockup pressure Pl at time t9 is set to a new “reference value”, and this “reference value” is updated. As a result, the “reference value” stored in the memory (not shown) of the CVT control unit 7 is updated.
Thereby, learning of the “reference value” of the lockup pressure Pl ends.

  And it progresses to step S13-> step S14, fuel cut control is performed, and the fuel supply to the engine 1 is stopped. As a result, the engine torque decreases from time t9. In the case shown in FIG. 4, the engine torque becomes a negative value at time t11. Thereby, the engine brake acts on the engine car A.

  Further, the process proceeds to step S15, and the forward clutch 31 being released is engaged. That is, the forward clutch pressure Pfc starts to increase. Here, the rising gradient of the forward clutch pressure Pfc is set to a value larger than the decreasing gradient of the forward clutch pressure Pfc when the forward clutch 31 is released. Therefore, the forward clutch 31 is engaged in a time shorter than the release time.

  At time t10, when the third threshold time elapses from time t9 when the increase of the forward clutch pressure Pfc starts, it is determined that the engagement of the forward clutch pressure Pfc is completed, and the process proceeds from step S16 to step S17, and the lock is performed. The up clutch 20 is engaged again. That is, the lockup capacity is increased by increasing the lockup pressure Pl.

  As a result, the torque converter differential rotation Δx decreases, and in the case shown in FIG. 4, the torque converter differential rotation Δx becomes zero at time t12. Thereafter, at time t13, the lockup pressure Pl reaches the engagement pressure, and the lockup clutch 20 is completely engaged.

  As described above, in the first embodiment, learning of the “reference value” of the lockup pressure Pl is performed between the time t6 and the time t9. At this time, the vehicle is on the coast while the accelerator is released. Therefore, the torque (engine torque) input from the input side of the driving force of the lockup clutch 20 is a coast torque, which is a very small torque that only maintains the engine speed at the idle speed. On the other hand, during learning of the lockup pressure Pl, the forward clutch 31 that is a frictional engagement element disposed between the torque converter 2 and the drive wheel 9 is released. Therefore, the torque (turbine torque) input from the output side of the driving force of the lockup clutch 20 becomes zero (see FIG. 5).

  Furthermore, the inertia torque acting on the engine 1 can be reduced by releasing the forward clutch 31. Therefore, the engine torque can be made extremely small. Moreover, since the engine 1 is not affected by the inertia fluctuation, the engine torque hardly fluctuates.

  Thereby, when learning the “reference value” of the lockup pressure Pl, the lockup clutch 20 has almost no torque input from the input side and the output side of the torque, and is affected by the input torque when learning the reference value. Can be prevented. As a result, it is possible to learn the lock-up pressure Pl with high accuracy without being affected by the torque input to the lock-up clutch 20. Therefore, the learning accuracy when learning the reference value of the lockup pressure Pl can be improved.

  Further, in the first embodiment, the fuel supply to the engine 1 is continued between the time t6 and the time t9 when the lockup pressure Pl is learned. At time t9, after learning of the “reference value” of the lockup pressure Pl ends, fuel cut control is executed, and fuel supply to the engine 1 is stopped.

As a result, the engine torque can be prevented from decreasing excessively during learning of the lockup pressure Pl, and the engine torque can be stably maintained. As a result, it is possible to learn the lock-up pressure Pl with high accuracy without being affected by the torque input to the lock-up clutch 20.
Further, as soon as the learning of the lockup pressure Pl ends, the fuel supply to the engine 1 is stopped, so that the fuel consumption can be improved.

[Prevention of passenger discomfort during learning]
In the lock-up pressure learning control according to the first embodiment, after it is determined that the accelerator is released at the time t2, the engine speed decrease gradient is detected after the vehicle speed reaches a predetermined vehicle speed or less at the time t3. . That is, the stable state of the engine torque is determined.

  Then, at the time t4 when it is determined that the engine torque input from the engine 1 to the lockup clutch 20 is stable, the forward clutch pressure Pfc starts to decrease.

  Thereby, the forward clutch 31 is released after the engine torque is stabilized. Therefore, as the forward clutch 31 is released, the power transmission path leading from the engine 1 to the drive wheels 9 is interrupted, but the engine torque is stable, making it difficult for the occupant to feel torque loss. Can do.

  In particular, in the first embodiment, the engine torque is detected at time t4 when a decrease time in which the engine torque decreases within a predetermined fluctuation range continues for a predetermined time after it is determined that the accelerator is released at time t2. Is judged to be stable. Therefore, the forward clutch 31 can be released by predicting and determining that the engine torque is stabilized before the engine torque is reduced to the coast torque.

  Here, for example, when the accelerator pedal is depressed during learning of the lock-up pressure Pl, learning is stopped. Therefore, when the accelerator is released, learning of the lock-up pressure Pl is started at the earliest possible timing. Is desirable. On the other hand, if the forward clutch 31 that is the frictional engagement element is released, learning of the lockup pressure Pl can be started. Therefore, there is a request to release the forward clutch 31 at the earliest possible timing.

  On the other hand, as in the first embodiment, by predicting that the engine torque is stable and releasing the forward clutch 31, it is possible to quickly learn the lockup pressure Plu while suppressing the occupant's uncomfortable feeling associated with the release of the clutch. You can start with timing. As a result, it becomes possible to start learning of the lockup pressure Pl at the earliest possible timing after the accelerator is released, and the appropriate learning opportunities can be increased.

[Other characteristic effects]
In the first embodiment, when learning the lockup pressure Plu, the frictional engagement element being engaged (the forward clutch 31 in FIG. 4) is released, and the frictional engagement element is re-engaged as learning ends.

  Here, the release speed when releasing the frictional engagement element is set to such an extent that no release shock is generated, and the engagement speed when re-engaging the frictional engagement element is set to a speed higher than the release speed.

  As a result, the frictional engagement element can be released while preventing the passenger from being shocked, and the power transmission path leading from the engine 1 to the drive wheels 9 can be quickly connected.

Next, the effect will be described.
In the vehicle control device of the first embodiment, the effects listed below can be obtained.

(1) A travel drive source (engine 1);
A torque converter 2 disposed between the travel drive source (engine 1) and drive wheels 9,
A lockup clutch 20 of the torque converter 2;
A friction engagement element (forward clutch 31) disposed between the torque converter 2 and the drive wheel 9;
When the rotational difference between the input rotational speed of the torque converter 2 (the rotational speed of the engine output shaft 11) and the output rotational speed of the torque converter 2 (the rotational speed with the torque converter output shaft 21) becomes a predetermined value. A learning control unit (CVT control unit 7) that learns a lock-up pressure Pl (reference value) that is a hydraulic pressure supplied to the lock-up clutch 20.
The learning control unit (CVT control unit 7) releases the frictional engagement element (forward clutch 31) and releases the lock-up clutch 20 when the lock-up clutch 20 travels in a state where the accelerator is released while the lock-up clutch 20 is engaged. The fastening capacity (lock-up capacity) is reduced to learn the lock-up pressure Pl.
Thereby, the learning accuracy at the time of learning the reference value of the lockup pressure Pl can be improved.

(2) The travel drive source is an engine 1 capable of stopping fuel supply,
The learning control unit (CVT control unit 7) continues to supply fuel to the engine 1 during execution of learning of the lockup pressure Pl, and after learning of the lockup pressure Pl ends, The fuel supply is stopped.
Thereby, in addition to the effect (1), the engine torque can be stably maintained during learning of the lockup pressure Pl, and the lockup pressure Pl can be learned with high accuracy.

(3) When the fluctuation of the drive source torque (engine torque) input from the travel drive source (engine 1) to the lockup clutch 20 is stabilized, the learning control unit (CVT control unit 7) The configuration is such that the (forward clutch 31) is released.
Thereby, in addition to the effect of (1) or (2), it is possible to make it difficult for the occupant to feel torque loss due to the release of the forward clutch 31.

(4) After the learning control unit (CVT control unit 7) determines that the accelerator release has occurred, a decrease time in which the drive source torque (engine torque) decreases within a predetermined fluctuation range has passed a predetermined time. At this time, the driving source torque (engine torque) is determined to be stable.
Thereby, in addition to the effect of (3), it is possible to release the forward clutch 31 by predicting that the engine torque is stabilized, and it becomes possible to start learning the lockup pressure Pl at the earliest possible timing. Appropriate learning opportunities can be increased.

(Example 2)
The vehicle control apparatus according to the second embodiment is an example applied to a vehicle including a continuously variable transmission between a torque converter and a friction engagement element.

First, the configuration will be described.
FIG. 6 is an overall system diagram schematically showing a drive system and a control system of an engine vehicle to which the vehicle control device of the second embodiment is applied. Hereinafter, based on FIG. 6, the structure of the engine vehicle C of Example 2 is demonstrated. In addition, about the structure similar to Example 1, the code | symbol same as Example 1 is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 6, the engine vehicle C to which the vehicle control device in the second embodiment is applied includes an engine 1 that is a travel drive source, a torque converter 2, a continuously variable transmission 100, a final reduction mechanism 5, Drive wheels 9. Further, the engine vehicle C includes a hydraulic control unit 6 that controls the line pressure PL, lockup pressure Pl, and the like, a CVT control unit 7 that outputs a control command to the continuously variable transmission 100, and an engine 1. And an engine control unit 8 for outputting a control command.

  As shown in FIG. 6, the continuously variable transmission 100 mounted on the engine vehicle C is interposed between the continuously variable transmission mechanism 110 and the continuously variable transmission mechanism 110 and the drive wheels 9, so that the And a sub-transmission mechanism 120 provided in series with the step transmission mechanism 110. “Provided in series” means that the continuously variable transmission mechanism 110 and the auxiliary transmission mechanism 120 are provided in series in the same power transmission path. The auxiliary transmission mechanism 120 may be directly connected to the transmission mechanism output shaft 111 of the continuously variable transmission mechanism 110 as in this example, or may be connected via another transmission or power transmission mechanism (for example, a gear train). It may be.

  The continuously variable transmission mechanism 110 is a belt type continuously variable transmission mechanism having a primary pulley 112, a secondary pulley 113, and a pulley belt 114. The primary pulley 112 includes a first fixed pulley 112a and a first slide pulley 112b arranged on the same axis as the torque converter output shaft 21 that is a variator input shaft. The first slide pulley 112b slides by the primary pressure Ppri guided to the primary pressure chamber 115. The secondary pulley 113 includes a second fixed pulley 113a and a second slide pulley 113b that are arranged coaxially with the transmission mechanism output shaft 111. The second slide pulley 113b is slid by the secondary pressure Psec guided to the secondary pressure chamber 116. The pulley belt 114 is stretched between a sheave surface that forms a V shape of the primary pulley 112 and a sheave surface that forms a V shape of the secondary pulley 113.

  The subtransmission mechanism 120 is a transmission mechanism having two forward speeds and one reverse speed. The auxiliary transmission mechanism 120 is connected to a Ravigneaux type planetary gear mechanism 121 in which two planetary gear carriers are connected, and a plurality of friction elements that are connected to a plurality of rotating elements constituting the Ravigneaux type planetary gear mechanism 121 and change their linkage state. Fastening elements (low brake 122, high clutch 123, reverse brake 124) are provided. By adjusting the supply hydraulic pressure (low brake pressure Plow, high clutch pressure PHi, reverse brake pressure Prb) to each friction engagement element 122-124, and changing the engagement / release state of each friction engagement element 32-34, The gear position of the transmission mechanism 120 is changed. That is, if the low brake 122 is engaged and the high clutch 123 and the reverse brake 124 are released, the speed of the subtransmission mechanism 120 becomes the first speed. Further, if the high clutch 123 is engaged and the low brake 122 and the reverse brake 124 are released, the gear position of the subtransmission mechanism 120 becomes the second speed having a gear ratio smaller than the first speed. Further, the reverse brake 124 is engaged when the shift lever is in the R range position.

In the second embodiment, the transmission control valve 61 has a sub-transmission pressure solenoid valve 65A instead of the clutch / brake pressure solenoid valve 65 of the first embodiment.
The auxiliary transmission pressure solenoid valve 65A regulates the low brake pressure Plow supplied to the low brake 122, the high clutch pressure Phi supplied to the high clutch 123, and the reverse brake pressure Prb supplied to the reverse brake 124. .

  As described above, in the second embodiment, the continuously variable transmission 100 includes the continuously variable transmission mechanism 110 and the auxiliary transmission mechanism 120. As a result, the continuously variable transmission mechanism 110 is disposed between the torque converter 2 and the frictional engagement elements (low brake 122, high clutch 123, reverse brake 124) of the auxiliary transmission mechanism 120.

  Next, the lock-up pressure learning control process executed by the CVT control unit of the second embodiment will be described based on the flowchart shown in FIG. In addition, about the step similar to Example 1, the same step number is attached | subjected and detailed description is abbreviate | omitted.

In the lockup pressure learning control process of the second embodiment, as shown in FIG. 7, if it is determined in step S2 that the accelerator is released, the process proceeds to step S3A, where the vehicle speed is equal to or less than a predetermined vehicle speed set in advance. Judge whether or not. If YES (vehicle speed ≦ predetermined vehicle speed), the process proceeds to step S5A. If NO (vehicle speed> predetermined vehicle speed), the process proceeds to return.
Here, the “predetermined vehicle speed” refers to a vehicle speed at which the rotational inertia force on the input side and the output side of the lockup clutch 20 becomes weak and the input / output differential rotation can occur at the timing when the clutch is released, as in the first embodiment. It is.

  In step S5A, following the determination that vehicle speed ≦ predetermined vehicle speed in step S3A, the frictional engagement elements (low brake 122, high clutch 123, reverse brake 124) being engaged in the auxiliary transmission mechanism 120 are released, and the process proceeds to step S6. . Since step S6 and subsequent steps are the same as those in the first embodiment, description thereof is omitted.

Next, the operation will be described.
In the engine vehicle C of the second embodiment, the reference value (the rotational speed of the engine output shaft 11 that is the input rotational speed of the torque converter 2 and the torque converter output shaft 21 that is the output rotational speed of the torque converter 2) of the lockup clutch 20. When learning the lock-up pressure Pl when the rotation difference between and the torque value becomes a predetermined value, first, it is determined whether or not the lock-up clutch 20 built in the torque converter 2 is engaged (step S1).

  Subsequently, it is determined whether or not the accelerator is released when the lockup clutch 20 is engaged (step S2). If it is determined that the accelerator is released, the vehicle speed is detected. When it is determined that the vehicle speed is equal to or lower than the predetermined vehicle speed (step S3A), the frictional engagement element of the subtransmission mechanism 120 being engaged is released (step S5A).

  Thereafter, when a predetermined time has elapsed from the start of releasing the frictional engagement element, the lockup capacity is reduced, and learning of the “reference value” of the lockup pressure Pl is started. Subsequently, when the state where the torque converter differential rotation is at a predetermined value is maintained for a predetermined time, the lock-up pressure Pl at that time is set to a new “reference value”, and this “reference value” is updated.

  Then, when learning of the lockup pressure Pl ends, fuel cut control and reengagement of the released frictional engagement element are performed. Then, after a period of time when it can be determined that the frictional engagement element has been engaged, the lockup capacity is increased and the lockup clutch 20 is reengaged.

Here, in the engine vehicle C of the second embodiment, as described above, the continuously variable transmission mechanism 110 is disposed between the torque converter 2 and the frictional engagement elements (low brake 122, high clutch 123, reverse brake 124). Has been. Therefore, when the frictional engagement element is released in order to learn the lockup pressure Pl, the power transmission between the continuously variable transmission mechanism 110 and the drive wheels 9 is interrupted. As a result, there is no input of torque for rotating the continuously variable transmission mechanism 110, and proper rotation cannot be maintained.
If the rotation is not maintained in the continuously variable transmission mechanism 110, a gear ratio according to the vehicle speed cannot be realized even if the vehicle speed changes while the accelerator is released.

  On the other hand, in the second embodiment, unlike the first embodiment, after the occurrence of the accelerator foot separation is determined, the frictional engagement element of the auxiliary transmission mechanism 120 is released when the vehicle speed drops below a predetermined vehicle speed. Thereby, the release of the frictional engagement element can be started without waiting for the engine torque to stabilize. And learning of lockup pressure Pl can be started at an earlier timing compared with Example 1 by advancing the release start timing of a frictional engagement element. In addition, since the learning start timing is advanced, the learning end timing can also be advanced as compared with the case of the first embodiment, and the timing of re-engagement of the frictional engagement elements to be executed upon completion of the learning is also the case of the first embodiment. Faster than before.

  Therefore, in the second embodiment, the time required from the timing when the accelerator foot separation state occurs to the completion of re-engagement of the frictional engagement element can be shortened as compared with the first embodiment. Therefore, the time during which power transmission between the continuously variable transmission mechanism 110 and the drive wheels 9 is interrupted is shortened, and the time during which the gear ratio according to the vehicle speed cannot be achieved in the continuously variable transmission mechanism 110 is shortened. be able to.

Next, the effect will be described.
In the vehicle control device of the second embodiment, the following effects can be obtained.

(5) a continuously variable transmission (continuously variable transmission mechanism 110) disposed between the torque converter 2 and the frictional engagement element (low brake 122);
The learning control unit (CVT control unit 7) is configured to release the frictional engagement element (low brake 122) when the vehicle speed falls below a predetermined vehicle speed after determining the occurrence of accelerator release.
As a result, in addition to the effect of (1) or (2), the timing from the time when the accelerator release state occurs to the completion of re-engagement of the frictional engagement element (low brake 122) can be shortened. The time during which the ratio cannot be realized can be shortened.

  As mentioned above, although the vehicle control apparatus of this invention has been demonstrated based on Example 1 and Example 2, it is not restricted to these Examples about a concrete structure, Each claim of a claim is a claim. Design changes and additions are allowed without departing from the gist of the invention.

  In the first embodiment, the forward clutch 31 and the reverse brake 32 included in the forward / reverse switching mechanism 3 disposed between the torque converter 2 and the variator 4 are shown as the friction engagement elements. Further, in the second embodiment, the example in which the low brake 122, the high clutch 123, and the reverse brake 124 of the auxiliary transmission mechanism 120 provided in the continuously variable transmission 100 are used as the friction engagement elements. However, the present invention is not limited to this, and any frictional engagement element that cuts off the torque transmission path between the torque converter 2 and the drive wheel 9 is incorporated in, for example, a stepped automatic transmission and is engaged at a predetermined shift stage. Even a frictional engagement element or the like can be applied as the frictional engagement element of the present invention.

  Further, in the first embodiment, the vehicle speed decreases after it is determined that the accelerator is released at time t2, and the vehicle speed reaches a predetermined vehicle speed or less at time t3. However, even if the accelerator is released, the vehicle speed is not always decelerated. For example, if the vehicle is traveling on a downhill, the vehicle speed increases even when the vehicle is traveling with the accelerator released. Even in this case, if the vehicle speed is equal to or lower than the predetermined vehicle speed, the lockup pressure Pl can be learned.

  In the second embodiment, the time required from the timing when the accelerator release state occurs to the completion of re-engagement of the frictional engagement element is shortened as compared with the first embodiment. An example is shown in which the frictional engagement element is released when (vehicle speed ≦ predetermined vehicle speed) is established. However, it is not limited to this in order to shorten the time from the release of the accelerator foot to the completion of re-engagement of the friction engagement element. For example, the timing for starting the release of the frictional engagement element is set to the same timing as in the first embodiment (that is, waiting for the engine torque to stabilize), while the release speed of the frictional engagement element may be made faster than that in the first embodiment. .

  Furthermore, in the first embodiment and the second embodiment, an example in which the present invention is applied to an engine vehicle in which the traveling drive source is the engine 1 is shown, but the present invention is not limited to this. The present invention can also be applied to a hybrid vehicle having an engine and an electric motor as a travel drive source, or an electric vehicle using only an electric motor as a travel drive source.

1 Engine (traveling drive source)
11 Engine output shaft 2 Torque converter 20 Lock-up clutch 21 Torque converter output shaft 3 Forward / reverse switching mechanism 31 Forward clutch (friction engagement element)
32 Reverse brake (friction engagement element)
4 Variator 9 Drive Wheel 7 CVT Control Unit (Learning Control Unit)

Claims (5)

A traveling drive source;
A torque converter disposed between the travel drive source and the drive wheel;
A lockup clutch of the torque converter;
A frictional engagement element disposed between the torque converter and the drive wheel;
A learning control unit that learns a lock-up pressure that is a hydraulic pressure supplied to the lock-up clutch when a rotational difference between an input rotational speed of the torque converter and an output rotational speed of the torque converter becomes a predetermined value; ,
The learning control unit learns the lockup pressure by releasing the frictional engagement element and reducing the engagement capacity of the lockup clutch when traveling in a state where the accelerator is released while the lockup clutch is engaged. The vehicle control device characterized by performing. In the vehicle control device according to claim 1,
The travel drive source is an engine capable of stopping fuel supply,
The learning control unit continues the fuel supply to the engine during the learning of the lockup pressure, and stops the fuel supply to the engine after the learning of the lockup pressure is completed. Vehicle control device. In the vehicle control device according to claim 1 or 2,
The learning control unit releases the frictional engagement element when the fluctuation of the driving source torque input from the traveling driving source to the lockup clutch is stabilized. In the vehicle control device according to claim 3,
The learning control unit determines that the drive source torque is stable when a decrease time in which the drive source torque decreases within a predetermined fluctuation range after a predetermined time has elapsed after determining the occurrence of accelerator release. A vehicle control device. In the vehicle control device according to claim 1 or 2,
A continuously variable transmission disposed between the torque converter and the frictional engagement element;
The learning control unit releases the frictional engagement element when the vehicle speed decreases to a predetermined vehicle speed or less with the release of the accelerator foot.