JP2023005224A - Operation actuator of friction fastening element - Google Patents

Abstract

An actuator for operating a frictional engagement element is intended to achieve both improved responsiveness when the frictional engagement element is engaged and precise controllability of the engagement force. A actuating actuator (2) of a friction engagement element (1) includes an electric motor (21), a screw mechanism (22) that converts rotational force of the electric motor (21) into linear motion, a piston (23) that presses a friction plate (13), and a screw mechanism (22). and an oil-tight oil filling chamber 26 filled with hydraulic oil for transmitting linear motion to the piston 23, and the electric motor 21 moves the piston 23 from the predetermined release position a1 to the zero clearance position a2. Stroke control is executed to control the stroke amount of the piston 23 by controlling the rotation speed of the electric motor 21, and the output torque of the electric motor 21 is increased when moving the piston 23 from the zero clearance position a2 to the predetermined engagement position a3. Torque control is executed to control the transmission torque of the frictional engagement element 1 by controlling. [Selection drawing] Fig. 5

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuation actuator for a friction engagement element mounted on a vehicle such as an automobile.

A friction engagement element mounted on a vehicle is mounted, for example, on an automatic transmission that is connected to a drive source such as an engine and that includes a plurality of planetary gear sets. An automatic transmission is configured to selectively engage a plurality of frictional engagement elements to switch a power transmission path via each planetary gear set to achieve a plurality of forward gears and typically one reverse gear. It is

As the friction engagement element, a plurality of friction plates and a piston that presses the plurality of friction plates to engage the friction engagement element when hydraulic pressure is supplied to the hydraulic chamber are provided, and the friction engagement is performed using the hydraulically operated piston. Frictional fastening elements for fastening and releasing elements are known.

In this type of friction engagement element, the clearance between the plurality of friction plates becomes zero when engaged, and the position of the piston is adjusted so that the tip of the friction plate is in contact with or nearly in contact with the friction plate without the piston pressing the friction plate. By setting the zero clearance position, which is a state of zero clearance (hereinafter also referred to as “zero clearance state”), the stroke from the disengaged position to the engaged position can be shortened in advance, which may improve the responsiveness during engagement. be.

When the friction engagement element is engaged, it is desired to increase the stroke speed of the piston in the release side stroke region from the release position to the zero clearance position of the piston from the demand for responsiveness. It is conceivable to supply pressure. The hydraulic pressure supplied to the hydraulic chamber is generally generated by an oil pump driven by the engine and controlled by a hydraulic control device with a plurality of solenoid valves. Even after reaching the zero clearance position, high hydraulic pressure acts on the piston, and there is a risk of shock due to rapid engagement of the friction engagement element.

Patent Document 1 discloses an electric motor, a conversion mechanism for converting rotary motion of the electric motor into linear motion, and the conversion The friction engagement element is engaged and released by a hydraulic pressure generating piston different from the piston, which is connected to the mechanism and fitted in an oil-tight oil filling chamber filled with hydraulic oil for transmitting the linear motion to the piston. An actuation actuator is disclosed for performing In order to suppress the shock caused by abrupt engagement of the friction engagement element, the release side stroke set in advance is controlled by rotation speed control for controlling the rotation speed (hereinafter also referred to as "rotation speed") of the electric motor of the operating actuator. It is conceivable to increase only the stroke speed of the piston in the region.

Japanese Patent Publication No. 2015-514198

In order to control the engagement of the frictional engagement elements well, it is necessary to carefully control the transmission torque of the frictional engagement elements while the piston moves through the engagement side stroke region from the zero clearance position to the fully engaged position where the frictional engagement elements are completely engaged. must be controlled to

However, in the engagement-side stroke region, the rate of change in the torque of the friction engagement element with respect to the stroke amount is greater than in the release-side stroke region, resulting in poor controllability. Therefore, as described above, when the stroke amount of the piston is controlled by controlling the rotation speed of the electric motor and the engagement control of the frictional engagement element is executed, precise engagement control is not executed in the engagement side stroke area, and unexpected A shock may occur due to a change in the transmission torque.

SUMMARY OF THE INVENTION The present invention provides an actuator for operating a frictional engagement element that can achieve both improved responsiveness when the frictional engagement element is engaged and precise controllability of the engagement force.

The present invention is an actuator for a friction engagement element that presses and engages a plurality of friction plates that are provided between a drum and a hub and are alternately engaged with the drum and the hub, comprising:
An oil-tight state filled with an electric motor, a screw mechanism that converts the rotational force of the electric motor into linear motion, a piston that presses the friction plate, and hydraulic oil that transmits the linear motion of the screw mechanism to the piston. and an oil filling chamber of
The screw mechanism has a screw shaft and a nut that axially moves on the screw shaft and transmits a pressing force to the piston via the oil filling chamber,
The electric motor is
The stroke of the piston is controlled by controlling the rotation speed of the electric motor when moving the piston from a predetermined release position to a zero clearance position where the clearance between the friction plates is narrowed and the friction plates are in a zero clearance state. Stroke control is performed to control the amount of torque, and torque control is performed to control the transmission torque of the friction engagement element by controlling the output torque of the electric motor when moving the piston from the zero clearance position to a predetermined engagement position. provides an actuation actuator for a frictional engagement element in which is performed.

According to the present invention, the frictional engagement element is engaged by controlling the stroke of the electric motor in the disengagement-side stroke area, in which the ratio of the stroke change amount to the amount of change in the torque transmitted by the frictional engagement element is greater than that in the engagement-side stroke area. responsiveness can be improved.

In addition, in the engagement-side stroke region, where the ratio of change in the torque transmitted by the friction engagement element to the stroke change is greater than in the release-side stroke region, the torque of the electric motor is controlled to reduce the transmission torque when the friction engagement element is engaged. It is possible to perform precise control of The transmission torque of the friction engagement element is proportional to the hydraulic pressure, the hydraulic pressure is proportional to the nut pushing force, and the nut pushing force is proportional to the motor torque. Based on this, by controlling the torque of the electric motor, it is possible to directly control the transmission torque of the friction engagement element compared to the case of stroke control.

Furthermore, since the actuating actuator is composed of a ball screw mechanism, an oil-tight oil filling chamber, and a piston, the hydraulic pump is driven to maintain the oil pressure in the non-engaged state, preventing oil leakage from solenoid valves and the like. Energy loss for maintaining pressure in the non-engaged state can be suppressed, as in the case of suppressing a drop in hydraulic pressure due to

The screw mechanism is composed of a ball screw mechanism,
The screw shaft has a first pitch region in which a first pitch is formed on one side in the axial direction, and a second pitch region in which a second pitch is formed on the other side in the axial direction continuously from the first pitch region. and formed so that the second pitch is smaller than the first pitch,
The first pitch and the second pitch may be set to switch at the zero clearance position.

According to this configuration, by using a so-called variable pitch ball screw mechanism having a first pitch and a second pitch that are different in the screw mechanism, the stroke speed of the piston in the release side stroke region can be adjusted without increasing the size of the motor. can be increased, and the stroke speed can be reduced while securing the pressing force necessary for engaging the frictional engagement element in the engagement-side stroke region.

If the output of the electric motor is constant and the pitch of the screw shaft is set so as to obtain the maximum required rotation speed, the maximum required torque cannot be obtained. However, an increase in the output of the electric motor leads to an increase in the size of the electric motor. On the other hand, for example, by setting the first pitch to the maximum stroke speed at the time of engagement and setting the second pitch to the maximum required torque at the time of engagement, the maximum rotation speed and the maximum required torque A small motor can be used compared to a case where a large motor capable of outputting is mounted. As a result, it is possible to use a compact motor with good mountability while improving the stroke speed of the piston in the release side stroke region and securing the necessary fastening torque in the engagement side stroke region.

The contact area can be reduced compared to the case of using a slide screw mechanism for the screw mechanism, and the screw efficiency is improved. As a result, the motor torque is reduced and the size of the electric motor can be reduced.

Further comprising zero clearance position detection means for detecting the zero clearance position,
The zero-clearance position detection means may be configured to detect the zero-clearance position of the piston when the hydraulic pressure in the oil filling chamber rises.

According to this configuration, the zero clearance position detection means detects the position of the piston when the hydraulic pressure in the oil filling chamber rises as the actual zero clearance position. , the actual zero clearance position can be accurately detected even when there is a deviation between the actual release side stroke area and the designed release side stroke area.

The zero clearance position detecting means may be composed of a hydraulic switch.

According to this configuration, it is possible to detect the zero clearance position of the piston with a less expensive configuration than when using a hydraulic sensor or the like.

The zero clearance position detection means may be composed of a hydraulic sensor.

According to this configuration, more precise controllability can be obtained than in the case of using a hydraulic switch.

Further comprising zero clearance position detection means for detecting the zero clearance position,
Preferably, the zero-clearance position detection means detects the zero-clearance position of the piston when a ratio of the amount of change in torque transmitted by the friction engagement element to the amount of change in stroke of the piston reaches or exceeds a predetermined value.

According to this configuration, the ratio of the amount of change in the transmission torque of the friction engagement element to the amount of change in the stroke of the piston becomes equal to or greater than the predetermined value by the zero clearance position detection means, and the torque is higher than in the case of controlling the stroke of the electric motor. The position of the piston can be detected as the actual zero clearance position when the accuracy of the control is increased. As a result, the actual zero clearance position can be accurately determined even if there is a discrepancy between the actual release side stroke area and the designed release side stroke area due to, for example, the temperature characteristics of the friction plate, manufacturing errors, wear, etc. can be detected.

Provided is an actuation actuator for a frictional engagement element capable of achieving both improved responsiveness when the frictional engagement element is engaged and precise controllability of the engagement force.

FIG. 4 is a schematic diagram of a disengaged state of the operating actuator of the friction engagement element according to the embodiment of the present invention; FIG. 4 is a schematic diagram of a zero-clearance state of the actuating actuator of the friction engagement element; FIG. 4 is a schematic diagram of a engaged state of an actuator for operating a frictional engagement element; 1 is a block diagram showing the configuration of a control device for an automatic transmission provided with frictional engagement elements; FIG. FIG. 4 is a diagram showing the transmission torque of a friction engagement element with respect to the stroke amount of a piston; 4 is a flowchart for explaining an example of engagement control of a frictional engagement element; FIG. 6 is a diagram showing the transmission torque of the frictional engagement element with respect to the stroke amount of the piston, which is an enlarged part of the engagement-side stroke region in FIG. 5 ; 9 is a flowchart for explaining an example of engagement control of frictional engagement elements in the second embodiment; FIG. 4 is a schematic diagram showing the pitch of the screw shaft corresponding to the stroke of the piston;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the operating actuator 2 of the frictional engagement element 1 according to the first embodiment of the present invention, showing the released state of the operating actuator 2 of the frictional engagement element 1. As shown in FIG. The frictional engagement element 1 constitutes, for example, a plurality of clutches and brakes provided in an automatic transmission (not shown), and the operating actuator 2 is provided for each frictional engagement element.

The clutch as the frictional engagement element 1 includes a cylindrical drum 11, a cylindrical hub 12 having a smaller diameter than the drum 11, and the drum 11 and the hub 12 arranged axially between the drum 11 and the hub 12. A plurality of friction plates 13 alternately spline-engaged with each other, and an operating actuator 2 that presses the plurality of friction plates 13 to fasten them together. The plurality of friction plates 13 are pressed by a piston 23 provided in the operating actuator 2 to engage the clutch 1 .

Of the plurality of friction plates 13, the plurality of friction plates 13a disposed inside the drum 11 are spline-engaged with the drum 11 to be axially movable and rotatable integrally with the drum 11. It is A plurality of friction plates 13b arranged outside the hub 12 are spline-engaged with the hub 12 so as to be axially movable and integrally rotatable with the hub 12 . The friction plates 13a and 13b are alternately arranged and opposed to each other via facings 13c provided on both sides of the friction plates 13b. On the other axial side of the plurality of friction plates 13, a retaining plate 15 is spline-engaged with the drum 11 in the same manner as the friction plates 13a and is retained from the one axial side by a snap ring 14. ing.

The piston 23 is arranged on one side in the axial direction of the plurality of friction plates 13 and is axially movably fitted in a second cylinder 26b forming part of an oil filling chamber 26, which will be described later. On one axial side of the piston 23, a hydraulic chamber 27b is formed in an oil-tight state by the second cylinder 26b and the piston 23 to constitute a second oil filling chamber, and on the other axial side of the piston 23, a hydraulic chamber 27b is formed. A return spring 16 is provided to bias the piston 23 to one side (release side) in the axial direction.

The operating actuator 2 includes an electric motor 21, a screw mechanism 22 that converts the rotational force of the electric motor 21 into linear motion, a piston 23 that presses the friction plate 13, and an operation that transmits the linear motion of the screw mechanism 22 to the piston 23. It has an oil-tight oil filling chamber 26 filled with oil and a hydraulic pressure generating piston 24 fitted in the oil filling chamber 26 and different from the piston 23 .

The electric motor 21 is, for example, a brushless DC motor having a rotor (not shown) made up of permanent magnets and a stator (not shown) made up of coils. A motor rotation speed sensor (for example, a magnetic sensor such as a Hall element) 35 is arranged on the stator side facing the magnetic poles of the rotor. The motor rotation speed is calculated by synthesizing a waveform with a constant period based on the position detection signal from the Hall element, and calculating the rotation speed from that period. A position signal detected by the motor rotation speed sensor 35 is input to the control device 30 (see FIG. 4). The electric motor 21 can be switched between rotation speed control for controlling the rotation speed of the electric motor 21 and torque control for controlling the torque of the electric motor 21. Control of the electric motor 21 will be described later.

The screw mechanism 22 is, for example, a ball screw mechanism having a top-type ball circulation mechanism. The screw mechanism 22 includes a screw shaft 22a, a nut 22b that moves in the axial direction as the screw shaft 22a rotates, and a plurality of rolling elements (not shown) interposed between the screw shaft 22a and the nut 22b. Prepare. The screw shaft 22a in this embodiment is configured by the rotating shaft of the electric motor 21, but may be configured so that power is transmitted via the rotating shaft of the electric motor 21 and a gear or the like.

A substantially semicircular ball rolling groove 22c is spirally formed on the outer peripheral surface of the screw shaft 22a. The ball rolling grooves 22c are formed so that the pitch changes at different positions in the axial direction of the screw shaft 22a. The screw mechanism 22 in this embodiment is configured by a pitch variable ball screw mechanism.

A substantially semicircular nut rolling groove (not shown) facing the ball rolling groove 22c of the screw shaft 22a is formed on the inner peripheral surface of the nut 22b. The balls are arranged between the ball rolling groove 22c and the nut rolling groove (not shown). As a result, the ball rolling groove 22c and the nut rolling groove are screwed together via the balls, and when the screw shaft 22a is rotated by the electric motor 21, the balls circulate while rolling in the circulation path to rotate the nut 22b. Move axially.

The oil filling chamber 26 includes a first oil filling chamber 27a formed in an oil-tight state by a first cylinder 26a filled with hydraulic oil and a hydraulic pressure generating piston 24 fitted to the first cylinder 26a, and a second oil filling chamber 27a. A hydraulic chamber 27b as a second oil filling chamber formed in an oil-tight state by the cylinder 26b and the piston 23 fitted to the second cylinder 26b, a first oil filling chamber 27a and a second oil filling chamber 27b. It has a connecting hydraulic line 26c.

A reservoir tank 26e is connected to the first oil filling chamber 27a through a connecting portion 26d provided on the first cylinder 26a. The reservoir tank 26e is filled with hydraulic oil, and the connecting portion 26d is released only when the hydraulic pressure in the first oil filling chamber 27a becomes less than the hydraulic pressure in the reservoir tank 26e, so that the first oil is A check valve 26f is provided for supplying hydraulic oil to the filling chamber 27a.

The hydraulic pressure generating piston 24 is connected to the nut 22b via a connecting member 25, and is configured to move axially in conjunction with the axial movement of the nut 22b. . As a result, axial movement of the nut 22b accompanying rotation of the electric motor 21 of the screw mechanism 22 is transmitted to the hydraulic pressure generating piston 24 via the connecting member 25, and when the hydraulic pressure generating piston 24 moves in the axial direction, the first Hydraulic oil in the oil filling chamber 27a flows into the second oil filling chamber 27b via the hydraulic line 26c, and the piston 23 strokes toward the engagement (the other axial direction) side.

In FIG. 1, the frictional engagement element 1 is shown in a released state in which the hydraulic pressure is discharged from the hydraulic chamber 27b and the piston 23 is moved to the anti-friction plate 13 side by the biasing force of the return spring 16. As shown in FIG.

When the clutch 1 is engaged, when the electric motor 21 of the operating actuator 2 is rotated in the disengaged state shown in FIG. 1 and the nut 22b is stroked toward the engagement side, as shown in FIG. 26a to the other side in the axial direction. Axial movement of the hydraulic pressure generating piston 24 causes hydraulic fluid in the first cylinder 26a (first oil filling chamber 27a) to flow into the second cylinder 26b (second oil filling chamber 27b) via the hydraulic line 26c. , the piston 23 moves toward the friction plate 13 against the biasing force of the return spring 16 .

At this time, the nut 22b is stroked from the nut release position b1 on the screw shaft 22a corresponding to the predetermined release position a1 of the piston 23 to the nut zero clearance position b2 on the screw shaft 22a corresponding to the zero clearance position a2 of the piston 23. do. Due to the stroke of the nut 22b at this time, the hydraulic pressure in the oil filling chamber 26 (hydraulic chamber 27b) is lower than the engagement hydraulic pressure P1 corresponding to the pressing force required to engage the frictional engagement element 1 and resists the biasing force of the return spring 16. Then, a holding oil pressure P2 is supplied to hold the piston 23 at the zero clearance position a2 (see FIG. 5).

Further, when the nut 22b is stroked toward the fastening side in the zero clearance state shown in FIG. 2, the hydraulic pressure generating piston 24 further moves in the first cylinder 26a to the other side in the axial direction as shown in FIG. Axial movement of the hydraulic pressure generating piston 24 causes hydraulic fluid in the first cylinder 26a to flow into the second cylinder 26b (hydraulic chamber 27b) via the hydraulic conduit 26c, increasing the hydraulic pressure in the hydraulic chamber 27b. , the piston 23 presses the friction plate 13, and the friction plate 13 is sandwiched between the retaining plate 15 fixed to the drum 11 and the piston 23, so that the friction engagement element 1 is engaged. It will be in a fastened state.

At this time, the nut 22b moves from the nut zero clearance position b2 to the nut fastening position b3 on the screw shaft 22a corresponding to the fastening position a3 where the piston 23 presses the friction plate 13 and the friction fastening element 1 is in the fastening state. do. Due to the stroke of the nut 22b at this time, the oil filling chamber 26 (hydraulic chamber 27b) is supplied with the engagement hydraulic pressure P1 corresponding to the pressing force required to engage the frictional engagement element 1 (see FIG. 5).

On the other hand, when the frictional engagement element 1 is disengaged, if the nut 22b is stroked to the disengagement side in the engaged state shown in FIG. is in contact or almost in contact with the friction plate 13, the pressing force of the piston 23 is released, and the friction engagement element 1 is brought into the zero clearance state.

Further, when the nut 22b is stroked to the release side (from the nut zero clearance position b2 to the nut release position b1) in the zero clearance state shown in FIG. , the friction engagement element 1 is released.

An automatic transmission (not shown) having a plurality of frictional engagement elements 1 includes a control device 30 that controls each operating actuator 2 in each frictional engagement element 1 to form a gear stage according to the driving state. . As shown in FIG. 4, the controller 30 receives a signal from a range sensor 31 that detects the range selected by the driver's operation, and a vehicle speed sensor 32 that detects the speed of the vehicle equipped with the automatic transmission. A signal from, a signal from an accelerator opening sensor 33 that detects the operation amount (accelerator opening) of the accelerator pedal by the driver, a signal from the engine speed sensor 34 that detects the speed of the engine mounted on the vehicle , a motor rotation speed sensor 35 for detecting the rotation speed of the electric motor 21 of the operating actuator 2, and a signal from an oil pressure sensor 36 provided above the oil filling chamber 26, and the like. The control device 30 is mainly composed of a microcomputer.

The control device 30 outputs a control signal to each operating actuator 2 based on various input signals to control the automatic transmission. In the shift control of the automatic transmission, for example, the target shift stage is determined based on the vehicle speed detected by the vehicle speed sensor 32, the accelerator opening detected by the accelerator opening sensor 33, and a predetermined shift map.

When shifting to the target shift speed, the actuating actuators 2 corresponding to the disengagement side frictional engagement element and the engagement side frictional engagement element to be replaced are controlled.

When the frictional engagement element 1 is engaged, in the release side stroke region from the release position a1 of the piston 23 to the zero clearance position a2, it is desired to increase the stroke speed of the piston 23 from the demand for responsiveness. It is necessary to increase only the stroke speed of the piston in the preset release-side stroke region by the rotation speed control that controls the speed (hereinafter also referred to as "rotation speed").

On the other hand, in order to perform engagement control of the frictional engagement element satisfactorily, the frictional engagement element 1 is moved through the engagement side stroke region from the zero clearance position a2 to the complete engagement position a3 where the frictional engagement element 1 is completely engaged. It is necessary to precisely control the transmission torque of

As shown in FIG. 5, the ratio of the amount of change in the transmission torque of the frictional engagement element 1 to the amount of change in stroke in the engagement-side stroke region is large, resulting in poor controllability. Therefore, when the engagement control of the friction engagement element 1 is executed by controlling the stroke amount of the piston by controlling the rotation speed of the electric motor, precise engagement control is not executed in the engagement-side stroke region, resulting in unexpected A change in transmission torque may cause a shock.

The control device 30 is provided with a motor control unit 131 that controls the electric motor 21. The motor control unit 131 is designed to improve responsiveness when the frictional engagement elements are engaged and achieve both precise controllability of the engagement force. It is provided with a configuration that enables

The motor control unit 131 controls the stroke amount of the piston 23 by controlling the rotation speed of the electric motor 21 so that the rotation speed of the electric motor 21 becomes the target rotation speed when the shift control is performed by the control device 30. A target torque, which is a control target value of the output torque of the electric motor 21, is determined based on the torque requested by the driver (for example, calculated from the accelerator opening), and the electric motor 21 is controlled so as to achieve the target torque. and the torque control state to be selectively executed.

The electric motor 21 performs stroke control when moving the piston 23 from the predetermined release position a1 to the zero clearance position a2 (when the piston 23 is positioned in the release side stroke area relative to the zero clearance position a2), and the piston 23 is moved from the zero clearance position a2 to the complete engagement position a3 of the frictional engagement element 1 (when the piston 23 is positioned in the engagement side stroke region from the zero clearance position a2), torque control is executed. .

The motor control unit 131 controls a drive circuit (not shown) such as an inverter circuit for driving the electric motor 21 so that the electric motor 21 rotates at the maximum rotational speed in the stroke control state. The drive circuit is controlled so that the electric motor 21 outputs the required output torque necessary for the piston 23 to generate the required piston pushing force calculated from the required torque of the vehicle.

The motor control unit 131 calculates the stroke amount and stroke position of the piston 23 for switching between stroke control and torque control of the electric motor 21 . The motor control section 131 calculates the stroke amount of the piston 23 based on the signal from the motor speed sensor 35 . For example, the rotation angle of the screw shaft 22a is calculated based on the change in the pulse according to the rotation of the electric motor 21 output by the Hall element, which is the motor rotation speed sensor 35, and the calculated rotation angle of the screw shaft 22a is calculated. , the stroke amount of the piston 23 is calculated based on the stroke amount of the nut 22b determined by the pitch of the screw shaft 22a, the pressure receiving area of the hydraulic pressure generating piston 24, the pressure receiving area of the piston 23, and the like. Note that the relationship between the rotation angle of the screw shaft 22a and the stroke amount of the piston 23 may be stored in advance as a map in the storage unit of the motor control unit 131, and the map may be calculated based on the calculated rotation angle of the screw shaft 22a. The stroke amount of the piston 23 may be read from .

The motor control unit 131 calculates the stroke position of the piston 23 based on the stroke amount of the piston 23 . The stroke position of the piston 23 is obtained by adding the calculated stroke amount of the piston 23 to the predetermined released position a1 of the piston 23 with the predetermined released position a1 of the piston 23 as a reference position (zero). calculated as

The motor control unit 131 determines whether the calculated stroke position of the piston 23 is smaller than the zero clearance position a2 predetermined at the time of design (whether the piston 23 is positioned on the release side of the zero clearance position a2), When the stroke position of the piston 23 is located on the disengagement side of the designed zero clearance position a2, stroke control is executed so that the calculated stroke position of the piston 23 is greater than or equal to the designed zero clearance position a2 (located on the engagement side). ), execute torque control.

In this manner, the motor control unit 131 switches between the stroke control state and the torque control state of the electric motor 21 based on whether the piston 23 is positioned in the release stroke region or the engagement stroke region.
The stroke control state and torque control state of the electric motor 21 may be switched based on the stroke amount of the piston 23 . Specifically, when the stroke amount of the piston 23 from the release position a1 is smaller than the stroke amount from the release position a1 to the zero clearance position a2 predetermined at the time of design, stroke control is executed to If the stroke amount from the release position a1 is equal to or greater than the stroke amount from the release position a1 to the zero clearance position a2 predetermined at the time of design, torque control is executed.

The motor control unit 131 calculates a necessary output torque required of the electric motor 21 for performing torque control of the electric motor 21 . The motor control unit 131 uses the required transmission torque obtained from the accelerator opening, the vehicle speed, and the shift map stored in advance, the pressure receiving area of the piston 23, the effective radius of the friction plate, and the friction coefficient of the friction plate. A required piston pushing force of the piston 23 is calculated. The motor control unit 131 calculates the required output torque of the electric motor 21 based on the calculated required piston pushing force, the pitch of the screw shaft 22a, the efficiency of the ball screw, and the like.

FIG. 6 is a flowchart for explaining the control of the electric motor 21 when the frictional engagement element 1 is engaged. As shown in FIG. 6, the control device 30 controls the frictional engagement element 1 in which the control state of the electric motor 21 is switched according to the position of the piston 23 (the stage when the frictional engagement element is engaged).

In the control operation shown in FIG. 6, the target gear is determined based on the vehicle speed detected by the vehicle speed sensor 32, the accelerator opening detected by the accelerator opening sensor 33, and a predetermined shift map. It is started in a state where the piston 23 of the frictional engagement element 1, which is switched from disengagement to engagement at a stage, is positioned at a predetermined disengagement position a1. Engagement control of the frictional engagement element 1 when the frictional engagement element 1 moves from the disengaged state to the engaged state will be described.

First, the control device 30 calculates the current stroke position of the piston 23 . Specifically, the current stroke position is calculated from the predetermined release position a1 of the piston 23 and the stroke amount of the piston 23 in the previous control cycle (step S1). As for the stroke of the piston 23, since engagement control is started from the predetermined disengagement position a1, the stroke amount of the piston 23 in the previous control cycle is zero.

In step S2, it is determined whether or not the current stroke position of the piston 23 calculated in step S1 is smaller than the zero clearance position a2. Specifically, whether the current stroke position of the piston 23 with respect to the release position a1 is smaller than the zero clearance position a2 of the piston 23 with respect to the predetermined release position a1 when the release position a1 is set as a reference position (zero point). is determined.

The determination in step S2 may be determined by the stroke amount of the piston 23. In this case, the stroke amount of the piston 23 is smaller than the stroke amount from the predetermined release position a1 set at the time of design to the zero clearance position a2 at the time of design. It is determined whether

If the determination in step S2 is YES, i.e., if the stroke position of the piston 23 is located in the release side stroke area from the zero clearance position a2, the stroke control of the electric motor 21 is executed. In stroke control, the rotation speed of the electric motor 21 is set to the maximum rotation speed, the piston 23 is stroked, and the flow is returned.

In step S1 of the returned control cycle, the current stroke position is similarly calculated. If the determination in step S2 is NO, that is, if the stroke position of the piston 23 is positioned in the engagement side stroke area from the zero clearance position a2, torque control of the electric motor 21 is executed.

In the torque control, the required piston pushing force of the piston 23 is calculated from the required torque of the vehicle in step S4. Specifically, from the required torque of the vehicle obtained from the accelerator opening, the vehicle speed, and a pre-stored shift map, the pressure receiving area of the piston 23, the effective radius of the friction plate, and the friction coefficient of the friction plate A required piston pushing force of the piston 23 is calculated.

In subsequent step S5, the required output torque of the electric motor 21 is calculated. Specifically, based on the required piston pushing force calculated in step S4, the pitch of the screw shaft 22a, the efficiency of the ball screw, and the like, the torque required for the electric motor 21 for performing torque control of the electric motor 21 is determined. Calculate the required output torque. In step S6, the output torque of the electric motor 21 is set to the required output torque calculated in step S5, the piston 23 is stroked to the fully engaged position a3, and the flow is returned. From the zero clearance position a2 to the fully engaged position a3, for example, control may be performed with the required output torque of the motor according to changes in the transmission torque required for slip control or the like.

In this manner, in the disengagement side stroke region where the ratio of the stroke change amount to the change amount of the transmission torque of the frictional engagement element is large compared to the engagement side stroke region, the stroke of the electric motor 21 is controlled so that the frictional engagement element 1 is Responsiveness at the time of fastening can be improved.

In addition, in the engagement-side stroke region where the ratio of the amount of change in the transmission torque of the frictional engagement element 1 to the amount of stroke change is large compared to the release-side stroke region, by controlling the torque of the electric motor 21, the frictional engagement element 1 is engaged. It is possible to perform precise control of the transmission torque in The transmission torque of the friction engagement element 1 is proportional to the hydraulic pressure, the hydraulic pressure is proportional to the nut pushing force, and the nut pushing force is proportional to the motor torque. By torque-controlling the electric motor based on the force, the transmission torque of the friction engagement element 1 can be controlled more directly than in the case of stroke control.

Furthermore, since the actuation actuator 2 is composed of the ball screw mechanism 22, the oil-tight oil filling chamber 26, and the piston 23, the hydraulic pump is driven to maintain the hydraulic pressure in the non-engaged state, thereby operating the solenoid valve and the like. As in the case of suppressing a drop in hydraulic pressure due to oil leakage from a duct, energy loss for maintaining pressure in a non-engaged state can be suppressed.

In the first embodiment, the configuration for switching the electric motor 21 from stroke control to torque control at the design zero clearance position a2 was described. The rate of change in torque may deviate from the designed zero clearance position a2. In the second embodiment, the control switching position of the electric motor 21 is set to the stroke position of the piston 23 when the ratio (dσ/dx) of the amount of change in the transmission torque to the amount of stroke change is equal to or greater than a predetermined value. Set as position a4. A second embodiment will be described with reference to FIGS. 7 and 9. FIG. In the second embodiment, the method of switching the control state of the electric motor 21 is different from that in the first embodiment. Configurations common to those of the first embodiment are denoted by the same reference numerals and descriptions thereof are omitted.

FIG. 7 shows the transmission torque of the frictional engagement element 1 with respect to the stroke amount of the piston 23 in which a portion of the engagement-side stroke region in FIG. 5 is enlarged. As shown in FIG. 7, when the piston 23 is stroked toward the engagement side from the designed zero clearance position a2, the ratio of the amount of change in the transmission torque to the amount of stroke change (dσ1/dx1) is small for a while, and furthermore the stroke , the ratio of the amount of change in the transmission torque to the amount of stroke change (dσ2/dx2) may increase. There are areas with good properties. In the second embodiment, the actual zero clearance position a4 is set to the position of the piston 23 where the ratio of the amount of change in the transmission torque to the amount of stroke change is equal to or greater than a predetermined value and the controllability of the torque control is higher than that of the stroke control. do.

Here, the resolution of the electric motor 2 means the minimum value of the operation command of the electric motor 21 . The rotation resolution dθm of the electric motor 21 indicates the minimum angle (the angle at which the rotation of the electric motor 21 is chopped by one pulse) when the electric motor 21 rotates. The torque resolution dTm of the electric motor 21 is the minimum unit of output torque output from the electric motor 21 . For example, the rotational resolution of the electric motor 21 is set to 0.005 deg, and the torque resolution is set to 0.000064 Nm. Therefore, the highly accurate control state of the electric motor 2 also varies depending on the relationship between the rotation angle resolution dθm and the torque resolution dTm of the electric motor 21 and the change amount (dσ/dx) of the transmission torque with respect to the stroke change amount.

The stroke amount is proportional to the rotation angle, and the transmission torque is proportional to the motor output torque. Instead, a method for detecting the actual zero clearance position a4 will be described. By setting the torque resolution ratio (dTm/dθm) to the rotation angle resolution of the electric motor 21 to a predetermined value, the ratio of the transmission torque change amount to the stroke change amount (dT/dθ) is the rotation angle resolution of the electric motor 21. The position of the piston 23 when the ratio of the torque resolution (dTm/dθm) to the torque resolution (dT/dθ≧dTm/dθm) is set as the actual zero clearance position a4.

The motor control unit 131 determines that the ratio (dT/dθ) of the change amount of the transmission torque to the stroke change amount is smaller than the ratio (dTm/dθm) of the torque resolution to the rotation angle resolution of the electric motor 21 (dT/dθ<dTm /dθm), the stroke of the electric motor 21 is controlled.

On the other hand, when the ratio (dT/dθ) of the amount of change in the transmitted torque to the amount of stroke change is equal to or greater than the ratio (dTm/dθm) of the torque resolution to the angular resolution of the electric motor 21 (dT/dθ≧dTm/dθm). , torque-control the electric motor 21 .

In this embodiment, the ratio (dT/dθ) of the amount of change in the motor torque to the amount of change in the rotation angle of the electric motor 21 is used as the ratio (dσ/dx) of the amount of change in the transmission torque to the amount of stroke.

FIG. 8 is a flowchart for explaining the control of the electric motor 21 when the frictional engagement element 1 is engaged. As shown in FIG. 8, the control device 30 controls the frictional engagement element 1 in which the control state of the electric motor 21 is switched according to the position of the piston 23 (the stage when the frictional engagement element is engaged).

In the control operation shown in FIG. 8, the target gear is determined based on the vehicle speed detected by the vehicle speed sensor 32, the accelerator opening detected by the accelerator opening sensor 33, and a predetermined shift map. It is started in a state where the piston 23 of the frictional engagement element 1, which is switched from disengagement to engagement at a stage, is positioned at a predetermined disengagement position a1. Engagement control of the frictional engagement element 1 when the frictional engagement element 1 moves from the disengaged state to the engaged state will be described.

First, the controller 30 calculates the ratio dT/dθ of the amount of change in motor torque with respect to the motor rotation angle (step S1). Specifically, dT is the difference between the current motor torque T(n) and the motor torque T(n-1) in the previous control cycle, and dθ is the current rotation angle θ(n) of the motor and the previous is the difference from the rotation angle θ(n−1) of the motor in the control cycle of . The amount of change in motor torque may be obtained by detecting the current value of the electric motor 21, and the rotation angle of the motor may be calculated based on the signal from the rotation speed sensor.

In step S2, it is determined whether the ratio dT/dθ of the amount of change in motor torque with respect to the motor rotation angle calculated in step S1 is smaller than the ratio of motor torque resolution to motor rotation angle resolution (dTm/dθm). If the determination in step S2 is YES, that is, if the ratio dT/d? is executed (step S3). In stroke control, the rotation speed of the electric motor 21 is set to the maximum rotation speed, the piston 23 is stroked, and the flow is returned.

In step S1 of the returned control cycle, similarly, the ratio dT/dθ of the amount of change in motor torque to the motor rotation angle is calculated. If the determination in step S2 is NO, that is, if the ratio dT/d? executed.

In the torque control, the required piston pushing force of the piston 23 is calculated from the required torque of the vehicle in step S4. Specifically, from the required torque of the vehicle obtained from the accelerator opening, the vehicle speed, and a pre-stored shift map, the pressure receiving area of the piston 23, the effective radius of the friction plate, and the friction coefficient of the friction plate A required piston pushing force of the piston 23 is calculated.

In subsequent step S5, the required output torque of the electric motor 21 is calculated. Specifically, based on the required piston pushing force calculated in step S4, the pitch of the screw shaft 22a, the efficiency of the ball screw, and the like, the torque required for the electric motor 21 for performing torque control of the electric motor 21 is determined. Calculate the required output torque. In step S6, the output torque of the electric motor 21 is set to the required output torque calculated in step S5, the piston 23 is stroked to the fully engaged position a3, and the flow is returned. From the zero clearance position a2 to the fully engaged position a3, for example, control may be performed with the required output torque of the motor according to changes in the transmission torque required for slip control or the like.

According to the second embodiment, the ratio of the amount of change in the transmission torque of the friction engagement element to the amount of change in the stroke of the piston 23 is equal to or greater than the predetermined value, and the torque control is performed compared to the case where the stroke of the electric motor 21 is controlled. can be detected as the actual zero clearance position a4. As a result, the actual zero clearance position can be accurately determined even if there is a discrepancy between the actual release side stroke area and the designed release side stroke area due to, for example, the temperature characteristics of the friction plate, manufacturing errors, wear, etc. can be detected.

The zero clearance position may be detected using a hydraulic sensor 36 as piston position detecting means provided in the oil filling chamber 26 (see FIG. 1). The actual zero clearance position a4 is detected when the value of the oil pressure sensor 36 reaches or exceeds a predetermined threshold value P3, as shown in FIG. The predetermined threshold value P3 is set, for example, to a hydraulic pressure equal to or higher than the holding hydraulic pressure P2 at which the piston 23 maintains the state in which the clearances between the plurality of friction plates 13 are filled against the biasing force of the return spring 16 .

Also, the piston position detecting means may be constituted by a hydraulic switch. As a result, the zero clearance position can be detected with a less expensive configuration than when using a hydraulic sensor or the like. Further, the piston position detection means may be composed of a torque sensor that detects the rise of torque.

Further, the actuating actuator 2 of the frictional engagement element 1 is provided with a screw mechanism 22 for improving the responsiveness at the time of engagement and securing the pressing force while miniaturizing the motor. As shown in FIG. 9, the screw mechanism 22 is composed of a variable pitch ball screw mechanism, and for example, the screw mechanism disclosed in Japanese Patent No. 4366215 can be used. The screw mechanism 22 includes a first pitch region X1 in which the first pitch X11 is formed on one side in the axial direction of the screw shaft 22a, and a second pitch X21 which is continuous with the first pitch region X1 and is formed on the other side in the axial direction. and a second pitch region X2. The second pitch X21 is formed to be smaller than the first pitch X11. In this embodiment, as disclosed in Japanese Patent No. 4366215, the nut 22b includes a ball holding member (not shown) having rolling element transfer grooves and a case in which the ball holding member is rotatably accommodated. (not shown), and has a configuration in which the ball holding member rotates with respect to the case in response to the change in the pitch of the screw shaft.

The pitches X11 and X21 provided on the screw shaft 22a are the distances between adjacent thread grooves. This corresponds to the distance that the nut 22b moves in the axial direction when the motor 21) rotates once. As for the stroke amount of the nut when the electric motor 21 rotates once, the stroke amount in the first pitch area X1 is larger than the stroke amount in the second pitch area X2. Therefore, the stroke speed of the nut 22b in the first pitch region X1 is set faster than the stroke speed of the nut 22b in the second pitch region X2.

As described above, the piston 23 is stroked by the stroke of the nut 22b. The relationship between the first pitch region X1 and the second pitch region X2 where the stroke speed of the nut 22b changes and the stroke speed of the piston 23 will be described with reference to FIG. Here, for ease of explanation, it is assumed that the stroke amount of the nut 22b and the stroke amount of the piston 23 are the same, for example.

The first pitch region X1 is set to be the same as the stroke amount L1 from the preset release position a1 of the piston 23 to the zero clearance position (zero clearance position at the time of design in the first and second embodiments) a2. is set. The second pitch region X2 extends to the other side in the axial direction continuously from the first pitch region X1, and is set to be greater than or equal to a preset stroke amount from the zero clearance position a2 to the fastening position a3. .

A nut release position b1 corresponding to the case where the piston 23 is positioned at the predetermined release position a1 is set such that the tip position of the nut 22b is positioned at one end in the axial direction of the first pitch region X1. The nut zero clearance position b2 corresponding to the case where the piston 23 is positioned at the designed zero clearance position a2 is the boundary position ( It is set so as to be positioned at the end of the first pitch region X1 on the other side in the axial direction and the end of the second pitch region X2 on the one side in the axial direction. In other words, the first pitch X11 and the second pitch X21 are set to switch at the zero clearance position a2 when the piston 23 is designed.

As is well known, motor torque and motor rotation speed have an inversely proportional relationship, so if the output of the electric motor is constant, the rotation speed will decrease when the motor torque is increased, and when the rotation speed is increased, the rotation speed will decrease. Then, it has the characteristic that the torque decreases.

The first pitch region X1 corresponds to the stroke amount L1 from the release position a1 of the piston 23 to the designed zero clearance position a2. The nut 22b can be moved at a high rotational speed and a stroke speed faster than the second pitch region X2 without reducing the motor rotational speed.

On the other hand, the second pitch region X2 corresponds to the stroke amount L2 from the designed zero clearance position a2 of the piston 23 to the engagement position a3. is required, and along with this, the motor rotation speed decreases, and the nut 22b can be moved at a stroke speed slower than that in the first pitch region X1.

Therefore, when engaging the frictional engagement element 1, if the nut 22b is stroked over the first pitch region X1, the piston 23 will be in the zero clearance state, and in the zero clearance state, the nut 22b is further stroked over the second pitch region X2. By doing so, the friction plate 13 is pressed substantially simultaneously with the stroke of the nut 22b, and the friction engagement element 1 is fastened with good responsiveness.

Although the configuration in which the screw shaft 22a has the first pitch X11 and the second pitch X21 has been described, the pitches provided on the screw shaft 22a may be configured with three or more pitches. For example, a transition area having a transition pitch smaller than the first pitch X11 and greater than the second pitch X21 is formed in a transition portion connecting the first pitch area X1 and the second pitch area X2. good too. In the turning area, the pitch may be set so that the pitch gradually decreases from the first pitch area X1 toward the second pitch area X2. In this case, the design zero clearance position a2 may be set in the transition area.

In the present embodiment, the configuration in which the oil filling chamber 26 is provided with the first cylinder 26a, the second cylinder 26b, and the hydraulic line 26c fluidly connecting the first cylinder 26a and the second cylinder 26b has been described. However, the oil filling chamber 26 may be configured to include either one of the first cylinder 26a and the second cylinder 26b.

In this embodiment, the electric motor 21 of the actuating actuator 2 is configured by a brushless motor. .

In this embodiment, the configuration using the ball screw mechanism as the screw mechanism has been described, but the configuration is not limited to this, and other feed screw mechanisms may be used.

In this embodiment, an example in which the frictional engagement element 1 is a clutch is shown. A basically similar actuation actuator 2 may be provided.

The present invention is not limited to the illustrated embodiments, and various improvements and design changes are possible without departing from the gist of the invention.

As described above, according to the present invention, in the actuator for operating the frictional engagement element, it is possible to achieve both improved responsiveness when the frictional engagement element is engaged and precise controllability of the engagement force. There is a possibility that it will be preferably used in the field of the manufacturing industry of elements.

1 Friction Engagement Element 2 Operation Actuator 11 Drum 12 Hub 13 Plural Friction Plates 21 Electric Motor 22 Screw Mechanism 22a Screw Shaft 22b Nut 23 Piston 26 Oil Filling Chamber 36 Zero Clearance Position Detection Means (Hydraulic Sensor, Hydraulic Switch)
a1 Predetermined release position a2 Zero clearance position X1 First pitch region X2 Second pitch region X11 First pitch X21 Second pitch

Claims (6)

An actuating actuator for a frictional engagement element that presses and engages a plurality of friction plates that are provided between a drum and a hub and alternately engage the drum and the hub, the actuator comprising:
An oil-tight state filled with an electric motor, a screw mechanism that converts the rotational force of the electric motor into linear motion, a piston that presses the friction plate, and hydraulic oil that transmits the linear motion of the screw mechanism to the piston. and an oil filling chamber of
The screw mechanism has a screw shaft and a nut that axially moves on the screw shaft and transmits a pressing force to the piston via the oil filling chamber,
The electric motor is
By controlling the number of rotations of the electric motor when moving the piston from a predetermined released position to a zero clearance position where the clearance between the friction plates is reduced and the plurality of friction plates are in a zero clearance state, the piston Stroke control is executed to control the stroke amount of, and the transmission torque of the friction engagement element is controlled by controlling the output torque of the electric motor when moving the piston from the zero clearance position to the predetermined engagement position. Actuating actuator of a friction engagement element in which torque control is performed. The screw mechanism is composed of a ball screw mechanism,
The screw shaft has a first pitch region in which a first pitch is formed on one side in the axial direction, and a second pitch region in which a second pitch is formed on the other side in the axial direction continuously from the first pitch region. and formed so that the second pitch is smaller than the first pitch,
2. The operating actuator for a friction engagement element according to claim 1, wherein said first pitch and said second pitch are set to switch at said zero clearance position. Further comprising zero clearance position detection means for detecting the zero clearance position,
2. An actuator for a friction engagement element according to claim 1, wherein said zero clearance position detection means is configured to detect the zero clearance position of said piston when the hydraulic pressure in said oil filling chamber rises. 4. The operating actuator for a frictional engagement element according to claim 3, wherein said zero clearance position detection means comprises a hydraulic switch. 4. The operating actuator for a frictional engagement element according to claim 3, wherein said zero clearance position detection means comprises a hydraulic sensor. Further comprising zero clearance position detection means for detecting the zero clearance position,
2. The zero-clearance position detecting means detects the zero-clearance position of the piston when the ratio of the amount of change in the transmission torque of the friction engagement element to the amount of change in stroke of the piston reaches or exceeds a predetermined value. An actuation actuator of the described frictional engagement element.

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