JP7537245B2 - Automatic transmission control device - Google Patents

Description

The present invention relates to a control device for an automatic transmission.

Patent document 1 discloses an automatic clutch device equipped with a clutch that is automatically controlled to be connected and disconnected when the transmission is automatically shifted, which detects a minimum value of the engine rotation speed before the clutch rotation speed and the engine rotation speed are synchronized when the clutch is connected, and when the engine rotation speed increases after the detection of the minimum value, changes the clutch connection speed to a value greater than the connection start speed.

As described above, when the clutch connection speed is changed to a speed greater than the connection start speed, the automatic clutch device described in Patent Document 1 learns and corrects the clutch connection start speed to the increasing speed side from the next gear shift control.

Japanese Patent Application Publication No. 10-274260

However, in an automatic transmission that has a torque converter with a lock-up clutch, the clutch that is automatically controlled to be engaged and disengaged during gear changes may be displaced in the axial direction depending on the state of the lock-up clutch.

As a result, the learning value may fluctuate significantly depending on the state of the lock-up clutch, and there is a risk that the learning value may not be stable. If the learning value is not stable, the control may become unstable and the accuracy of clutch control may deteriorate.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide an automatic transmission control device that can prevent deterioration of clutch control accuracy even when the clutch is displaced axially due to the state of the lock-up clutch.

In order to achieve the above-mentioned object, the present invention provides a control device for an automatic transmission including a torque converter with a lock-up clutch connected to an internal combustion engine, a speed change mechanism that changes the rotation of the internal combustion engine and outputs it, a clutch provided between the torque converter and the speed change mechanism, and a clutch actuator that automatically operates the clutch, and is provided with a learning control unit that executes learning control to update a learning value of the engagement position of the clutch, and the learning control unit is configured to permit the learning when the lock-up clutch is engaged or released, to prohibit the learning at least during the engagement and release operations of the lock-up clutch, and if the learning is permitted when the lock-up clutch is released, to correct the learning value in accordance with the operating oil pressure of the lock-up clutch when the lock-up clutch is engaged, during the engagement operation, and during the release operation .

The present invention provides an automatic transmission control device that can prevent deterioration of clutch control accuracy even when the clutch is displaced axially due to the state of the lock-up clutch.

FIG. 1 is a schematic diagram of a vehicle equipped with an automatic transmission control device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the structure of a torque converter and a clutch mounted on a vehicle equipped with an automatic transmission control device according to one embodiment of the present invention. FIG. 3 is a flowchart showing the flow of the learning control process executed by the control device for an automatic transmission according to one embodiment of the present invention. FIG. 4 is a graph showing an area in which learning is permitted in the learning control executed by the automatic transmission control device according to one embodiment of the present invention. FIG. 5 is a flowchart showing a first modified example of the learning control executed by the control device for an automatic transmission according to one embodiment of the present invention. FIG. 6 is a graph showing an area in which learning is permitted in the learning control of the first modified example shown in FIG. FIG. 7 is a flowchart showing a second modified example of the learning control executed by the control device for an automatic transmission according to one embodiment of the present invention.

The control device for an automatic transmission according to one embodiment of the present invention is an automatic transmission control device that includes a torque converter with a lock-up clutch connected to an internal combustion engine, a speed change mechanism that changes the speed of the internal combustion engine and outputs it, a clutch provided between the torque converter and the speed change mechanism, and a clutch actuator that automatically operates the clutch. The control device is characterized in that it includes a learning control unit that executes learning control that updates a learning value of the engagement position of the clutch, and that the learning control unit permits learning when the lock-up clutch is engaged or released, and prohibits learning at least during the engagement and release operations of the lock-up clutch. As a result, the control device for an automatic transmission according to one embodiment of the present invention can prevent deterioration of the accuracy of the clutch control even when the clutch is displaced in the axial direction due to the state of the lock-up clutch.

Below, a vehicle equipped with an automatic transmission control device according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the vehicle 1 includes an internal combustion engine 2, an automatic transmission 3, drive wheels 4, and a control device 10.

The engine 2 has multiple cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The engine 2 is the power source for the vehicle 1.

The automatic transmission 3 is provided in the power transmission path between the engine 2 and the drive wheels 4. The automatic transmission 3 has a torque converter 30, a speed change mechanism 31, a clutch 32, and a clutch actuator 33.

The torque converter 30 is a so-called torque converter with a lock-up clutch, which has a lock-up clutch 35. The torque converter 30 is provided in the power transmission path between the engine 2 and the clutch 32, and transmits power via a fluid.

The torque converter 30 is connected to the clutch 32 via the turbine shaft 36. The torque converter 30 amplifies the torque generated by the engine 2 and outputs it to the transmission mechanism 31 via the clutch 32.

The lock-up clutch 35 is provided in the torque converter 30, and is capable of switching between an engaged state in which the crankshaft 21 of the engine 2 and the turbine shaft 36 are directly connected (hereinafter referred to as "direct connection"), and a released state in which the direct connection between the crankshaft 21 and the turbine shaft 36 is released. The detailed structures of the torque converter 30 and the lock-up clutch 35 will be described later.

The speed change mechanism 31 is provided in the power transmission path between the clutch 32 and the drive wheels 4, and has an input shaft 37 connected to the clutch 32, and an output shaft 38 connected to the drive wheels 4 via a differential (not shown).

The transmission mechanism 31 changes the speed of the rotation of the engine 2 that is output from the engine 2 and transmitted to the input shaft 37, and outputs it to the output shaft 38. The rotation output to the output shaft 38 is transmitted to the drive wheels 4 via a differential (not shown).

The transmission mechanism 31 is configured to be able to form multiple gear stages with different gear ratios by combining multiple gears with different numbers of teeth. Gear stages in the transmission mechanism 31 are automatically switched by a shift actuator (not shown).

The clutch 32 is provided in the power transmission path between the torque converter 30 and the transmission mechanism 31. The clutch 32 has a clutch wheel disc 32a connected to the turbine shaft 36 so as to be able to rotate together with it, and a clutch disc 32b connected to the input shaft 37 so as to be able to rotate together with it.

The clutch 32 can be switched between an engaged state in which the clutch disc 32b is pressed against the clutch wheel disc 32a to transmit power between the turbine shaft 36 and the input shaft 37, and a disconnected state in which the clutch disc 32b is separated from the clutch wheel disc 32a to disconnect the power transmission between the turbine shaft 36 and the input shaft 37.

The clutch 32 is designed so that the operation of switching between the engaged state and the disengaged state (hereinafter referred to as "clutch operation") is automatically performed by the clutch actuator 33. The detailed structure of the clutch 32 will be described later.

The clutch actuator 33 is electrically connected to the control device 10 and automatically performs clutch operation of the clutch 32 based on commands from the control device 10.

The control device 10 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

The ROM of the computer unit stores various constants, maps, and the like, as well as a program for causing the computer unit to function as the control device 10. In other words, the CPU executes the program stored in the ROM using the RAM as a working area, causing the computer unit to function as the control device 10 in this embodiment.

The control device 10 is connected to various devices such as the shift actuator, clutch actuator 33, and hydraulic control device 40 (not shown), as well as various sensors such as a crank angle sensor 50, a turbine speed sensor 51, a clutch speed sensor 52, a clutch position detection sensor 53, and a lock-up hydraulic sensor 54.

The hydraulic control device 40 controls the hydraulic oil pressure supplied to the lock-up clutch 35 and the clutch actuator 33 of the torque converter 30. The hydraulic control device 40 switches the lock-up clutch 35 between an engaged state and a released state by adjusting the magnitude of the hydraulic oil pressure supplied to the lock-up clutch 35 based on a command from the control device 10. The hydraulic control device 40 switches the clutch 32 between an engaged state and a released state by adjusting the magnitude of the hydraulic oil pressure supplied to the clutch actuator 33 based on a command from the control device 10.

The crank angle sensor 50 detects the rotation angle of the crankshaft 21 (hereinafter referred to as the "crank angle"). The control device 10 calculates the engine speed, which is the rotation speed of the engine 2, based on the information indicating the crank angle input from the crank angle sensor 50.

The turbine speed sensor 51 detects the rotation speed of the turbine shaft 36 (hereinafter referred to as "turbine speed"). The clutch speed sensor 52 detects the rotation speed of the input shaft 37 (hereinafter referred to as "clutch speed").

The clutch position detection sensor 53 detects the clutch position of the clutch 32. For example, the clutch position detection sensor 53 detects the position of the release bearing 73 of the clutch 32, which will be described later.

The lockup hydraulic pressure sensor 54 detects the hydraulic pressure supplied to the lockup clutch 35.

The control device 10 has the function of controlling the hydraulic control device 40 to switch the lockup clutch 35 to an engaged or released state based on predetermined lockup conditions.

The control device 10 functions as a clutch control unit 101 that controls the clutch 32 by referring to a map (not shown) that defines the relationship between the clutch position and the clutch transmission torque based on the clutch position detected by the clutch position detection sensor 53.

The control device 10 functions as a learning control unit 102 that executes learning control to update the learning value of the engagement position of the clutch 32 (hereinafter referred to as the "clutch engagement position"). The control device 10 performs learning in the learning control on the condition that a predetermined learning condition is met.

In this embodiment, the predetermined learning condition is that all of the following conditions (1) to (3) are continuously satisfied for a predetermined period of time or longer.
(1) The clutch actuator 33 is in a non-operating state, i.e., no hydraulic pressure is being generated. (2) The clutch rotation speed is less than a predetermined rotation speed. (3) The estimated temperature of the clutch disc 32b is less than a predetermined temperature.

The control device 10 can determine the estimated temperature of the clutch disc 32b, for example, from the difference in rotation speed between the turbine rotation speed and the clutch rotation speed, the clutch transmission torque, etc.

When no hydraulic pressure is generated in the clutch actuator 33, the control device 10 learns the position where the release bearing 73 (described later) abuts against the diaphragm spring 72 as the learned value of the clutch engagement position. The control device 10 updates the learned value of the clutch engagement position each time it performs learning.

In this embodiment, the control device 10 allows learning of the clutch engagement position when the lock-up clutch 35 is released, and prohibits such learning when the lock-up clutch 35 is engaged, during the engagement operation, and during the release operation.

Therefore, in this embodiment, even if the above-mentioned predetermined learning conditions are met, the control device 10 does not learn the clutch engagement position when the lock-up clutch 35 is in an engaged state, in the process of engaging, or in the process of releasing.

The reason why learning of the clutch engagement position is prohibited except when the lock-up clutch 35 is released is that the lock-up clutch 35 may displace in the axial direction during the engagement and disengagement operations of the lock-up clutch 35, and if the lock-up clutch 35 is displaced, the clutch position will change, and if learning is performed in such a situation, the learning value may fluctuate significantly. The reason why the clutch position changes with the axial displacement of the lock-up clutch 35 will be explained later.

In contrast, when the lock-up clutch 35 is released or engaged, the lock-up clutch 35 is less likely to displace in the axial direction, making it easier for the learning value to be stable. For this reason, in this embodiment, the configuration allows learning of the clutch engagement position when the lock-up clutch 35 is released.

When the lock-up clutch 35 is disengaged, this means that the lock-up clutch 35 is in a disengaged state, and more specifically, this means that the operating oil pressure of the lock-up clutch 35 is equal to or higher than a predetermined oil pressure P1. The predetermined oil pressure P1 is the lower limit of the operating oil pressure at which the lock-up clutch 35 can be considered to be in a disengaged state, and is experimentally determined in advance and stored in the ROM of the control device 10.

It is sufficient to be able to learn the clutch engagement position in a situation where the learning value is likely to be stable, so a configuration may be used in which learning of the clutch engagement position is permitted when the lock-up clutch 35 is engaged. This configuration will be explained in the first modified example described below.

When the lock-up clutch 35 is engaged, during the engagement operation, and during the release operation, the control device 10 corrects the learning value of the clutch engagement position according to the hydraulic pressure of the lock-up clutch 35.

The ROM of the control device 10 stores a correction map that is obtained by experiment beforehand to determine the relationship between the hydraulic pressure of the lock-up clutch 35 and the clutch engagement position. The control device 10 corrects the learned value of the clutch engagement position by referring to the correction map based on the hydraulic pressure of the lock-up clutch 35.

Next, referring to FIG. 2, the detailed structures of the torque converter 30, the lock-up clutch 35, and the clutch 32 will be described, along with the change in clutch position associated with the axial displacement of the lock-up clutch 35.

(Torque converter and lock-up clutch)
The torque converter 30 has a front cover 61 and a pump shell 62 connected to the front cover 61. The front cover 61 is connected to the crankshaft 21 of the engine 2 via a drive plate 63. As a result, the front cover 61 and the pump shell 62 rotate integrally with the crankshaft 21.

The torque converter 30 includes a pump impeller 64 fixed to the pump shell 62 and a turbine runner 65 facing the pump impeller 64. The turbine runner 65 is connected to the turbine shaft 36.

As shown in FIG. 2, the inside of the torque converter 30 is divided into an apply chamber 30A and a release chamber 30B, with the lock-up clutch 35 as the boundary. The apply chamber 30A or the release chamber 30B is supplied with hydraulic pressure depending on the operating state of the lock-up clutch 35.

When the lock-up clutch 35 is engaged, hydraulic oil pressure is supplied to the apply chamber 30A (hereinafter, this hydraulic oil pressure is referred to as the "apply pressure") and hydraulic oil is discharged from the release chamber 30B. When the apply pressure rises and the hydraulic oil pressure in the release chamber 30B (hereinafter, this hydraulic oil pressure is referred to as the "release pressure") falls, a pressure difference acts on the lock-up clutch 35 in the front-to-rear direction, causing the lock-up clutch 35 to move closer to the front cover 61.

When the lock-up clutch 35 is pressed against the front cover 61, the lock-up clutch 35 is switched to an engaged state. This directly connects the turbine shaft 36 to the crankshaft 21, and the power of the engine 2 is transmitted to the turbine shaft 36 without passing through a fluid.

When the lock-up clutch 35 is released, release pressure is supplied to the release chamber 30B and hydraulic oil is discharged from the apply chamber 30A. When the apply pressure decreases and the release pressure increases, a pressure difference acts on the lock-up clutch 35 in the front-to-rear direction, causing the lock-up clutch 35 to move in a direction away from the front cover 61. This causes the lock-up clutch 35 to be pulled away from the front cover 61, and the lock-up clutch 35 is switched to a released state.

(clutch)
The clutch 32 has a clutch wheel disc 32 a fastened to the turbine shaft 36 by a bolt 70 , and a clutch disc 32 b disposed so as to be movable in the axial direction of the input shaft 37 .

The clutch 32 includes a clutch cover 71 and a diaphragm spring 72. The clutch cover 71 is fastened to the clutch wheel disc 32a by bolts (not shown) and rotates together with the clutch wheel disc 32a and the turbine shaft 36.

The diaphragm spring 72 is attached to the clutch cover 71, and has an annular pressure plate 72a attached to its outer periphery. The diaphragm spring 72 biases the pressure plate 72a toward the clutch disc 32b, pressing the clutch disc 32b against the clutch wheel disc 32a.

A release bearing 73 is installed on the outside of the input shaft 37. When the release bearing 73 is moved forward (towards the clutch 32) in the axial direction of the input shaft 37 by the release fork 74, it presses the center of the diaphragm spring 72 forward.

When the release bearing 73 presses the center of the diaphragm spring 72, the diaphragm spring 72 releases the pressure plate 72a from biasing the pressure plate 72a against the clutch disc 32b. This removes the pressure of the clutch disc 32b against the clutch wheel disc 32a, and the clutch disc 32b is separated from the clutch wheel disc 32a. As a result, the rotation of the crankshaft 21 is no longer transmitted to the input shaft 37 via the turbine shaft 36.

When the release bearing 73 is moved rearward in the axial direction of the input shaft 37 by the release fork 74, it moves away from the center of the diaphragm spring 72. In this state, the pressure plate 72a is biased by the diaphragm spring 72, and the clutch disc 32b is pressed against the clutch wheel disc 32a. This transmits the rotation of the crankshaft 21 to the input shaft 37 via the turbine shaft 36.

The release fork 74 is connected to a hydraulic clutch actuator 33 and is operated by the clutch actuator 33. The above-mentioned clutch position detection sensor 53 is provided, for example, in this clutch actuator 33, and detects the position from the amount of pressure of the clutch actuator 33 that presses the release fork 74.

(Changes in clutch position due to axial displacement of the lock-up clutch)
Next, the reason why the clutch position changes in accordance with the axial displacement of the lock-up clutch 35 in the automatic transmission 3 configured as above will be described.

(When the lock-up clutch is released)
When the lock-up clutch 35 is released, the release pressure is supplied to the release chamber 30B. At this time, the release pressure supplied to the release chamber 30B acts on the turbine shaft 36 as a pressing force that presses the turbine shaft 36 toward the clutch 32.

The turbine shaft 36 is restricted from moving in the axial direction because the circlip 80 fitted in the groove abuts against the bearing 81, which in turn abuts against the enlarged diameter portion 36a of the turbine shaft 36, but there is some play in the axial direction between the groove and the circlip 80. In addition, a recess 36b is formed at the end of the turbine shaft 36 on the input shaft side, and the outer peripheral surface of the outer ring 82a of the bearing 82 is loosely fitted into the inner peripheral surface of this recess 36b.

When the release pressure acts as a pressing force on the turbine shaft 36, the turbine shaft 36 moves toward the input shaft 37 by the amount of backlash between the groove and the circlip 80. As a result, the clutch wheel disc 32a fastened to the turbine shaft 36 and the diaphragm spring 72 attached to the clutch cover 71 move toward the transmission mechanism 31 (see Figure 1).

As a result, the release bearing 73 moves toward the transmission mechanism 31, and the clutch position detected by the clutch position detection sensor 53 changes to the engaged side. As a result, as shown in FIG. 4, when the lock-up clutch 35 is released, the clutch engaged position changes to the engaged side compared to when the lock-up clutch 35 is engaged.

The release pressure indicated by P1 in FIG. 4 is the predetermined hydraulic pressure P1 at which the lock-up clutch 35 can be considered to be in a released state. Therefore, the region where the release pressure is equal to or greater than the predetermined hydraulic pressure P1 is the region where learning of the clutch engagement position is permitted (referred to as the "learning permitted region" in FIG. 4).

In contrast, in FIG. 4, the region where the release pressure is less than the predetermined hydraulic pressure P1 is a region where learning of the clutch engagement position is prohibited (referred to as the "learning prohibited region" in FIG. 4) and where the learning value of the clutch engagement position is corrected (referred to as the "learning value correction region" in FIG. 4).

As shown in FIG. 4, when the lock-up clutch 35 is released, the clutch engagement position changes to the engagement side compared to when the lock-up clutch 35 is engaged, but the change in the clutch engagement position relative to the change in release pressure is small or there is no change. Therefore, the clutch engagement position when the lock-up clutch 35 is released is more stable than when the lock-up clutch 35 is released and engaged.

(When the lock-up clutch is engaged)
When the lock-up clutch 35 is engaged, the release pressure is discharged from the release chamber 30B and the apply pressure is supplied to the apply chamber 30A. In this way, when the lock-up clutch 35 is engaged, the release pressure is discharged from the release chamber 30B, so that the pressing force pressing the turbine shaft 36 towards the clutch 32 disappears.

At this time, the pressing load (hereinafter referred to as the "preload load") of the clutch actuator 33 acting on the release fork 74 causes the release bearing 73 to move toward the torque converter 30. This causes the diaphragm spring 72 to be pressed toward the torque converter 30, and the clutch cover 71 and clutch wheel disc 32a, which are integrated with the diaphragm spring 72, move toward the torque converter 30.

As a result, the turbine shaft 36 fastened to the clutch wheel disc 32a moves toward the engine 2 (see FIG. 1) by the amount of play between the groove and the circlip 80, and the clutch position detected by the clutch position detection sensor 53 changes to the disengaged side. As a result, as shown in FIG. 4, when the lock-up clutch 35 is engaged, the clutch engagement position changes to the disengaged side compared to when the lock-up clutch 35 is released.

The force that moves the clutch 32 and turbine shaft 36 toward the torque converter 30 due to the preload load is smaller than the force that the clutch actuator 33 applies pressure to the diaphragm spring 72 to switch the clutch 32 to the disengaged state.

As shown in FIG. 4, when the lock-up clutch 35 is engaged, the clutch engagement position changes to the disengaged side compared to when the lock-up clutch 35 is released. However, just as when the lock-up clutch 35 is released, the change in the clutch engagement position relative to the displacement of the release pressure is small or there is no change. Therefore, the clutch engagement position when the lock-up clutch 35 is engaged is also stable compared to when the lock-up clutch 35 is released and engaged.

(Lock-up clutch disengaged and engaged)
As shown in FIG. 4, when the lockup clutch is being released or engaged, the change in the clutch engagement position relative to the change in release pressure is greater than when the lockup clutch is being released or engaged.

For this reason, the conditions during the disengagement and engagement of the lockup clutch are not favorable for learning the clutch engagement position. Therefore, in this embodiment, as described above, learning of the clutch engagement position is prohibited during the engagement and disengagement of the lockup clutch 35.

(Learning Control)
Next, a process flow of the learning control executed by the control device 10 of this embodiment will be described with reference to Fig. 3. The learning control shown in Fig. 3 is repeatedly executed at predetermined time intervals.

As shown in FIG. 3, the control device 10 determines whether or not a predetermined learning condition is satisfied (step S1). The predetermined learning condition is as described above. If the control device 10 determines in step S1 that the predetermined learning condition is not satisfied, it terminates this learning control.

When the control device 10 determines in step S1 that the predetermined learning condition is satisfied, it determines whether the lock-up clutch 35 is in a released state (step S2). For example, the control device 10 can determine that the lock-up clutch 35 is in a released state when the release pressure for releasing the lock-up clutch 35, i.e., a release pressure equal to or greater than a predetermined hydraulic pressure P1, is detected by the lock-up hydraulic pressure sensor 54.

If the control device 10 determines in step S2 that the lock-up clutch 35 is not in a released state, it ends this learning control. If the control device 10 determines in step S2 that the lock-up clutch 35 is in a released state, it allows learning of the clutch engagement position (step S3).

Next, the control device 10 learns the clutch engagement position (step S4) and ends this learning control.

As described above, the control device for the automatic transmission according to this embodiment is configured to permit learning of the clutch engagement position when the lock-up clutch 35 is released, and to prohibit such learning when the lock-up clutch 35 is engaged, during the engagement operation, and during the release operation.

With this configuration, the control device for the automatic transmission according to this embodiment can learn the clutch engagement position in a situation where the learning value is likely to be stable, and can avoid learning the clutch engagement position in a situation where the learning value fluctuates greatly. This makes it possible to prevent the accuracy of clutch control from deteriorating, even if the clutch 32 is displaced in the axial direction due to the state of the lock-up clutch 35.

The control device for the automatic transmission according to this embodiment is also configured to correct the learning value of the clutch engagement position in accordance with the hydraulic pressure of the lock-up clutch 35 when the lock-up clutch 35 is engaged, during the engagement operation, and during the release operation.

With this configuration, the automatic transmission control device according to this embodiment can use a clutch engagement position that takes into account the deviation in clutch control, even if the actual clutch engagement position deviates from the learned clutch engagement position when the lock-up clutch 35 is released. This makes it possible to prevent the accuracy of clutch control from deteriorating, even if the actual clutch engagement position deviates from the learned value of the clutch engagement position.

In this embodiment, the learning control allows learning of the clutch engagement position when the lock-up clutch 35 is released, but the learning control shown in the first or second modified example described below may also be used.

(First Modification)
In the learning control according to the first modification, learning of the clutch engagement position is permitted when the lock-up clutch 35 is engaged, and is prohibited when the lock-up clutch 35 is released, during the engagement operation, and during the release operation.

When the lockup clutch 35 is engaged means that the lockup clutch 35 is in an engaged state, and more specifically, means that the release pressure of the lockup clutch 35 is equal to or lower than a predetermined hydraulic pressure P2 as shown in FIG. 6. The predetermined hydraulic pressure P2 is the lower limit of the release pressure at which the lockup clutch 35 can be considered to be in an engaged state, and is experimentally determined in advance and stored in the ROM of the control device 10.

In FIG. 6, the region where the release pressure is equal to or less than a predetermined hydraulic pressure P2 is the region where learning of the clutch engagement position is permitted (referred to as the "learning permitted region" in FIG. 6).

In contrast, in FIG. 6, the region where the release pressure exceeds the predetermined hydraulic pressure P2 is a region where learning of the clutch engagement position is prohibited (referred to as the "learning prohibited region" in FIG. 6) and where the learning value of the clutch engagement position is corrected (referred to as the "learning value correction region" in FIG. 6).

Next, the process flow of the learning control according to the first modified example will be described with reference to FIG. 5. The learning control shown in FIG. 5 is repeatedly executed at a predetermined time interval.

As shown in FIG. 5, the control device 10 determines whether or not a predetermined learning condition is satisfied (step S11). The predetermined learning condition is as described above. If the control device 10 determines in step S11 that the predetermined learning condition is not satisfied, it terminates this learning control.

When the control device 10 determines in step S11 that the predetermined learning condition is satisfied, it determines whether the lock-up clutch 35 is engaged (step S12). For example, the control device 10 can determine that the lock-up clutch 35 is engaged when the release pressure for engaging the lock-up clutch 35, i.e., a release pressure equal to or lower than the predetermined hydraulic pressure P2, is detected by the lock-up hydraulic pressure sensor 54. The lock-up clutch 35 may also be determined to be engaged based on the applied pressure.

If the control device 10 determines in step S12 that the lock-up clutch 35 is not engaged, it ends this learning control. If the control device 10 determines in step S12 that the lock-up clutch 35 is engaged, it allows learning of the clutch engagement position (step S13).

Next, the control device 10 learns the clutch engagement position (step S14) and ends this learning control.

In the first modified example, the control device 10 corrects the learning value of the clutch engagement position according to the hydraulic pressure of the lock-up clutch 35 when the lock-up clutch 35 is released, during the engagement operation, and during the release operation.

In this way, even when performing learning control according to the first modified example, as in this embodiment, the clutch engagement position can be learned in a situation where the learning value is likely to be stable, and learning of the clutch engagement position can be avoided in a situation where the learning value fluctuates greatly. This makes it possible to prevent the accuracy of clutch control from deteriorating even when the clutch 32 is displaced in the axial direction due to the state of the lock-up clutch 35.

In addition, even if the actual clutch engagement position deviates from the clutch engagement position learned when the lock-up clutch 35 is engaged, a clutch engagement position that takes this deviation into account can be used for clutch control. This makes it possible to prevent the accuracy of clutch control from deteriorating even if the actual clutch engagement position deviates from the learned value of the clutch engagement position.

(Second Modification)
In the learning control according to the second modification, it is set in advance whether learning of the clutch engagement position is permitted when the lock-up clutch 35 is engaged or when the lock-up clutch 35 is released, and the learning of the clutch engagement position is permitted based on this setting. This setting can be changed as appropriate by the user, etc.

The process flow of the learning control according to the second modified example will be described with reference to FIG. 7. The learning control shown in FIG. 7 is repeatedly executed at a predetermined time interval.

As shown in FIG. 7, the control device 10 determines whether or not the predetermined learning condition is satisfied (step S21). The predetermined learning condition is as described above. If the control device 10 determines in step S21 that the predetermined learning condition is not satisfied, it terminates this learning control.

If the control device 10 determines in step S21 that the predetermined learning conditions are met, it determines whether the setting allows learning of the clutch engagement position when the lock-up clutch 35 is released (step S22).

If the control device 10 determines in step S22 that the setting allows learning of the clutch engagement position when the lock-up clutch 35 is released, it determines whether the lock-up clutch 35 is in a released state (step S23).

If the control device 10 determines in step S23 that the lock-up clutch 35 is not in a released state, the control device 10 ends this learning control. If the control device 10 determines in step S23 that the lock-up clutch 35 is in a released state, the control device 10 permits learning of the clutch engagement position (step S24).

Next, the control device 10 learns the clutch engagement position (step S25) and ends this learning control.

If the control device 10 determines in step S22 that the setting does not permit learning of the clutch engagement position when the lock-up clutch 35 is released, it determines whether the lock-up clutch 35 is engaged (step S26).

If the control device 10 determines in step S26 that the lock-up clutch 35 is not engaged, it ends this learning control. If the control device 10 determines in step S26 that the lock-up clutch 35 is engaged, it allows learning of the clutch engagement position (step S27).

Next, the control device 10 learns the clutch engagement position (step S28) and ends this learning control.

In the second variant, if the control device 10 allows learning of the clutch engagement position when the lock-up clutch 35 is engaged, it corrects the learning value of the clutch engagement position according to the hydraulic pressure of the lock-up clutch 35 when the lock-up clutch 35 is released, during the engagement operation, and during the release operation.

In addition, in the second modified example, if the control device 10 allows learning of the clutch engagement position when the lock-up clutch 35 is released, the control device 10 corrects the learning value of the clutch engagement position according to the hydraulic pressure of the lock-up clutch 35 when the lock-up clutch 35 is engaged, during the engagement operation, and during the release operation.

In this way, even when performing learning control related to the second modified example, as in the present embodiment, the clutch engagement position can be learned in a situation where the learning value is likely to be stable, and learning of the clutch engagement position can be avoided in a situation where the learning value fluctuates greatly. This makes it possible to prevent the accuracy of clutch control from deteriorating even when the clutch 32 is displaced in the axial direction due to the state of the lock-up clutch 35.

In addition, even if the actual clutch engagement position deviates from the learned clutch engagement position when the lock-up clutch 35 is engaged or released, a clutch engagement position that takes this deviation into account can be used for clutch control. This makes it possible to prevent the accuracy of clutch control from deteriorating even if the actual clutch engagement position deviates from the learned value of the clutch engagement position.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

1. Vehicle 2. Engine (internal combustion engine)
3 Automatic transmission 4 Drive wheel 10 Control device 21 Crankshaft 30 Torque converter 30A Apply chamber 30B Release chamber 31 Transmission mechanism 32 Clutch 32a Clutch wheel disc 32b Clutch disc 33 Clutch actuator 35 Lock-up clutch 36 Turbine shaft 37 Input shaft 38 Output shaft 40 Hydraulic control device 50 Crank angle sensor 51 Turbine rotation speed sensor 52 Clutch rotation speed sensor 53 Clutch position detection sensor 54 Lock-up hydraulic pressure sensor 72 Diaphragm spring 73 Release bearing 74 Release fork 101 Clutch control unit 102 Learning control unit

Claims (2)

A control device for an automatic transmission comprising: a torque converter with a lock-up clutch connected to an internal combustion engine; a speed change mechanism that changes the speed of rotation of the internal combustion engine and outputs the rotation; a clutch provided between the torque converter and the speed change mechanism; and a clutch actuator that automatically operates the clutch,
a learning control unit that executes learning control for updating a learning value of the engagement position of the clutch,
The learning control unit is
The learning is permitted when the lock-up clutch is engaged or disengaged,
The learning is prohibited at least during an engagement operation and a release operation of the lock-up clutch ,
a control device for an automatic transmission, characterized in that, when the learning is permitted when the lock-up clutch is released, the learning value is corrected in accordance with the hydraulic oil pressure of the lock-up clutch when the lock-up clutch is engaged, during the engagement operation, and during the release operation . A control device for an automatic transmission comprising: a torque converter with a lock-up clutch connected to an internal combustion engine; a speed change mechanism that changes the speed of rotation of the internal combustion engine and outputs the rotation; a clutch provided between the torque converter and the speed change mechanism; and a clutch actuator that automatically operates the clutch,
a learning control unit that executes learning control for updating a learning value of the engagement position of the clutch,
The learning control unit is
The learning is permitted when the lock-up clutch is engaged or disengaged,
The learning is prohibited at least during an engagement operation and a release operation of the lock-up clutch ,
a control device for an automatic transmission, wherein when the learning is permitted when the lockup clutch is engaged, the learning value is corrected in accordance with the hydraulic oil pressure of the lockup clutch when the lockup clutch is released, during the engagement operation, and during the release operation .

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