JP7537244B2 - 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 a clutch, there is a risk that the clutch wheel disc may bend due to centrifugal force as the clutch rotation speed increases, and if such bending of the clutch wheel disc occurs, there is a risk that the clutch engagement position may be displaced.

As a result, the learning value may fluctuate significantly with fluctuations in clutch rotation speed, and the learning value may not be stable. If the learning value is not stable, 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 the accuracy of clutch control even when the clutch engagement position is displaced due to fluctuations in clutch rotation speed.

In order to achieve the above-mentioned object, the present invention provides a control device for an automatic transmission comprising a shift mechanism which changes the rotation of an internal combustion engine, which is a power source, and outputs the rotation, a clutch provided between the internal combustion engine and the shift mechanism, and a clutch actuator which automatically operates the clutch, and further comprises a learning control unit which 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 a clutch rotation speed, which is the rotation speed of the clutch, is equal to or lower than a predetermined value, and to correct the learning value in accordance with the clutch rotation speed when the clutch rotation speed exceeds the predetermined value .

The present invention provides an automatic transmission control device that can prevent deterioration of clutch control accuracy even when the clutch engagement position is displaced due to fluctuations in clutch rotation speed.

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 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.

The automatic transmission control device according to one embodiment of the present invention is a control device for an automatic transmission that includes a speed change mechanism that changes the rotation of an internal combustion engine, which is a power source, and outputs the rotation, a clutch provided between the internal combustion engine and the speed change mechanism, and a clutch actuator that automatically operates the clutch. The control device includes a learning control unit that executes learning control that updates a learning value of the clutch engagement position, and is characterized in that the learning control unit allows learning when the clutch rotation speed, which is the rotation speed of the clutch, is equal to or lower than a predetermined value. As a result, the automatic transmission control device according to one embodiment of the present invention can prevent the accuracy of the clutch control from deteriorating even when the clutch engagement position is displaced due to fluctuations in the clutch rotation speed.

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 its operating state can be switched 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 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 engine 2 and the transmission mechanism 31, more specifically, 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 rotatable together with the turbine shaft 36, and a clutch disc 32b connected to the input shaft 37 so as to be rotatable together with the turbine shaft 36.

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 described above, and various sensors such as a crank angle sensor 50, a turbine speed sensor 51, a clutch speed sensor 52, and a clutch position detection sensor 53.

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, which is the rotation speed of the clutch 32 (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 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 both of the following conditions (1) and (2) 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 estimated temperature of the clutch disc 32b is lower 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 clutch rotation speed is equal to or less than a predetermined value Ncth, and prohibits learning of the clutch engagement position when the clutch rotation speed exceeds the predetermined value Ncth.

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 if the clutch rotation speed exceeds the predetermined value Ncth.

The reason why learning of the clutch engagement position is prohibited when the clutch rotation speed exceeds the predetermined value Ncth is that when the clutch rotation speed exceeds the predetermined value Ncth, the clutch wheel disc 32a may bend due to centrifugal force, and if the clutch wheel disc 32a is bent, the clutch engagement position will change, and if learning is performed in such a situation, the learning value may fluctuate significantly.

In other words, as shown in FIG. 4, when the clutch rotation speed exceeds the predetermined value Ncth, the displacement of the clutch engagement position relative to the change in the clutch rotation speed is large, that is, the displacement of the clutch engagement position per unit clutch rotation speed is large, so the learning value also varies greatly according to the clutch rotation speed. The reason why the clutch engagement position is displaced due to the curvature of the clutch wheel disc 32a will be described later.

In contrast, when the clutch rotation speed is equal to or less than the predetermined value Ncth, the clutch wheel disc 32a is less likely to bend, and the learning value is more likely to be stable. That is, as shown in FIG. 4, when the clutch rotation speed is equal to or less than the predetermined value Ncth, the displacement of the clutch engagement position per unit clutch rotation speed is small or there is no displacement, so the learning value does not fluctuate greatly depending on the clutch rotation speed, and the learning value is stable. For this reason, in this embodiment, the learning of the clutch engagement position is permitted when the clutch rotation speed is equal to or less than the predetermined value Ncth.

The predetermined value Ncth is the upper limit of the clutch rotation speed at which the displacement of the clutch engagement position per unit clutch rotation speed falls within a predetermined range and the clutch engagement position can be considered to be approximately constant; it is determined in advance through experimentation and stored in the ROM of the control device 10.

When the clutch rotation speed exceeds a predetermined value Ncth, the control device 10 corrects the learning value of the clutch engagement position according to the clutch rotation speed.

The ROM of the control device 10 stores a correction map that experimentally determines the relationship between the clutch rotation speed 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 clutch rotation speed.

Next, referring to Figure 2, we will explain the detailed structure of the clutch 32 and the displacement of the clutch engagement position.

(clutch)
As shown in FIG. 2, the clutch 32 has a clutch wheel disc 32 a fastened to a turbine shaft 36 by bolts (not shown), and a clutch disc 32 b disposed so as to be movable in the axial direction of an 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 diaphragm spring 72 near the center, the outer periphery of the diaphragm spring 72 is displaced rearward in the axial direction of the input shaft 37, with the attachment point of the diaphragm spring 72 to the clutch cover 71 as the fulcrum, and the urging of the pressure plate 72a to the clutch disc 32b by the diaphragm spring 72 is released. This eliminates the pressing force 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.

(Displacement of clutch engagement position)
Next, a description will be given of the reason why, in the automatic transmission 3 configured as above, when the clutch rotational speed exceeds the predetermined value Ncth, the clutch engagement position is displaced in accordance with fluctuations in the clutch rotational speed.

When the clutch rotation speed exceeds a predetermined value Ncth, centrifugal force causes the clutch wheel disc 32a to bend radially outward as indicated by arrow A, and as a result, the clutch cover 71 fastened to the clutch wheel disc 32a bends in the direction indicated by arrow B.

When the clutch cover 71 is bent in this manner, the attachment portion of the diaphragm spring 72 relative to the clutch cover 71 (the "fulcrum" described above) is displaced rearward in the axial direction of the input shaft 37. Furthermore, the bending of the clutch cover 71 described above displaces the outer periphery of the diaphragm spring 72 radially outward.

As a result, the displacement of the fulcrum and outer circumference of the diaphragm spring 72 described above causes the center of the diaphragm spring 72 to move toward the turbine shaft 36. Then, 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 turbine shaft 36 so as to follow the diaphragm spring 72.

As a result, compared to when the clutch rotation speed is equal to or lower than the predetermined value Ncth, the release bearing 73 moves toward the clutch 32 (in the direction indicated by the arrow C in FIG. 2), 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, in the rotation range where the clutch rotation speed exceeds the predetermined value Ncth, the clutch engagement position is displaced to the disengaged side compared to when the clutch rotation speed is equal to or lower than the predetermined value Ncth.

Furthermore, in the rotational range where the clutch rotation speed exceeds a predetermined value Ncth, the displacement of the clutch engagement position per unit clutch rotation speed becomes larger than when the clutch rotation speed is equal to or lower than the predetermined value Ncth.

For this reason, the rotational range where the clutch rotational speed exceeds the predetermined value Ncth is an unfavorable situation for learning the clutch engagement position. Therefore, in this embodiment, as described above, learning of the clutch engagement position is prohibited when the clutch rotational speed exceeds the predetermined value Ncth.

Depending on the shape of the clutch wheel disc 32a, the direction in which the clutch cover 71 curves may be opposite to that in this embodiment (opposite to the direction indicated by arrow B). In this case, the release bearing 73 moves toward the transmission mechanism 31 (see FIG. 1) and the clutch engagement position is displaced toward the engagement side, compared to when the clutch rotation speed is equal to or lower than the predetermined value Ncth. Even when the clutch engagement position is displaced toward the engagement side, the amount of displacement of the clutch engagement position per unit clutch rotation speed is large, so learning of the clutch engagement position is prohibited in the rotation range where the clutch rotation speed exceeds the predetermined value Ncth, as in this embodiment.

(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.

If the control device 10 determines in step S1 that the predetermined learning conditions are met, it determines whether the clutch rotation speed is equal to or less than a predetermined value Ncth (step S2).

If the control device 10 determines in step S2 that the clutch rotation speed is not equal to or less than the predetermined value Ncth, it ends this learning control. If the control device 10 determines in step S2 that the clutch rotation speed is equal to or less than the predetermined value Ncth, 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 in this embodiment is configured to allow learning of the clutch engagement position when the clutch rotation speed is equal to or less than a predetermined value Ncth.

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 engagement position is displaced due to fluctuations in the clutch rotation speed.

The control device for the automatic transmission according to this embodiment is also configured to correct the learning value of the clutch engagement position according to the clutch rotation speed when the clutch rotation speed exceeds a predetermined value Ncth.

With this configuration, the control device for the automatic transmission according to this embodiment can use a clutch engagement position that takes into account the deviation when the actual clutch engagement position deviates from the learned clutch engagement position when the clutch rotation speed is equal to or less than a predetermined value Ncth. This makes it possible to prevent the accuracy of clutch control from deteriorating even when the actual clutch engagement position deviates from the learned value of the clutch engagement position.

In this embodiment, the learning of the clutch engagement position is permitted when the clutch rotation speed is equal to or less than the predetermined value Ncth. However, for example, even if the clutch rotation speed is equal to or less than the predetermined value Ncth, learning of the clutch engagement position may be prohibited when the clutch rotation speed is less than a predetermined lower limit value Nclow. Furthermore, when the clutch rotation speed is less than the lower limit value Nclow, the learning value of the clutch engagement position may be corrected.

As shown in FIG. 4, in the rotational region where the clutch rotational speed is below the lower limit Nclow, the displacement of the clutch engagement position per unit clutch rotational speed is smaller than in the rotational region where the clutch rotational speed exceeds the predetermined value Ncth, but the displacement of the clutch engagement position per unit clutch rotational speed is larger than in the rotational region where the clutch rotational speed is above the lower limit Nclow and below the predetermined value Ncth.

Therefore, by prohibiting learning of the clutch engagement position when the clutch rotation speed is less than the lower limit value Nclow, it is possible to learn the clutch engagement position with less or no change in the clutch engagement position.

The lower limit Nclow is the lower limit of the clutch rotation speed at which the displacement of the clutch engagement position per unit clutch rotation speed falls within a predetermined range and the clutch engagement position can be considered to be approximately constant, and is determined in advance through experimentation and stored in the ROM of the control device 10.

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 31 speed change 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 71 clutch cover 72 diaphragm spring 72a pressure plate 73 release bearing 74 release fork 101 clutch control unit 102 learning control unit

Claims (1)

A control device for an automatic transmission including a speed change mechanism that changes the speed of rotation of an internal combustion engine, which is a power source, and outputs the rotation, a clutch provided between the internal combustion engine 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 a clutch rotation speed, which is a rotation speed of the clutch, is equal to or lower than a predetermined value,
a control device for an automatic transmission, the control device comprising: a clutch rotation speed control unit that corrects the learning value in accordance with the clutch rotation speed when the clutch rotation speed exceeds the predetermined value;

Images