JPH0419461A - Operation control method for reciprocating liquid pressure actuator of friction engaging element - Google Patents

Abstract

PURPOSE:To high accurately control operation of a liquid pressure actuator by correcting a pressure value of supply pressure liquid in accordance with duty ratio to obtain a correction value and deciding an actuator rod to reach a predetermined stroke when an integrated pressure value of this correction pressure value reaches a predetermined value. CONSTITUTION:In an ECU65, a friction engaging element 30 is actuated through an actuator rod 79, associated with a piston 59, by generating a pressure to rise up by supplying pressure liquid, whose pressure value is controlled by duty-controlling a solenoid valve 67, to a pressure chamber 81 regulated by the piston 59 in a liquid pressure actuator 31. A switch 93 is on-operated, when the rod 79 is moved by a predetermined distance, to obtain a correction pressure value by correcting the pressure value of pressure liquid, supplied to the pressure chamber 81 from on-operation of the switch 93, in accordance with a level of duty ratio of the pressure value, and supply of the pressure liquid to the pressure chamber 81 is controlled by deciding a stroke amount of the actuator rod 79 to reach a predetermined stroke, corresponding to desired operation of the friction engaging element 30, when an integrated pressure value, obtained by integrating this correction pressure value, reaches a predetermined value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to the operation of frictional engagement elements, such as drum brakes and friction clutches, which are built into automatic transmissions for vehicles and are used to change gears. The present invention relates to a reciprocating hydraulic actuator for controlling a reciprocating hydraulic actuator, and more particularly to a method for controlling the operation of a reciprocating hydraulic actuator of a frictional engagement element for controlling the stroke amount of an actuator rod in the hydraulic actuator.

(Prior Art) Automatic transmissions for vehicles operate frictional engagement elements such as friction clutches and drum boogies using reciprocating hydraulic actuators, and thereby operate any rotating drum or gear according to the driving condition of the vehicle. The desired speed change is automatically performed by selecting rotational elements such as the following.

Here, one of the frictional engagement elements of the automatic transmission for vehicles includes:
There is a kickdown brake to control the rotation of the kickdown drum, but if we focus on this kickdown brake, the reciprocating hydraulic actuator that controls its operation is controlled by a kickdown servo consisting of a hydraulic cylinder. It is configured. That is, in the kickdown servo,
A piston is slidably fitted and defines a pressure chamber within the kickdown servo. A piston rod that protrudes outside the kickdown servo extends from the piston, and this piston rod serves as an actuator rod that engages with the brake shoe of the kickdown brake and operates the kickdown brake. ing. Therefore, according to the kickdown servo described above, by supplying pressure fluid to the pressure chamber and raising the pressure in the pressure chamber, the actuator rod is driven via the piston, and thereby,
By tightening the brake shoes of the kickdown brake to the kickdown drum, it is possible to apply a brake to the rotation of the kickdown drum.

(Problem to be Solved by the Invention) By the way, in the operation of the kickdown servo described above, it is difficult to determine whether the brake shoe of the kickdown brake is completely tightened to the kickdown drum, that is, in an engaged state. For example, this determination can be estimated from the maximum stroke amount of the actuator rod. However, it is difficult to detect this maximum stroke amount with a sensor, etc. Therefore, it is difficult to detect the maximum stroke amount of the actuator rod. It is conceivable to obtain it from the pressure value in the pressure chamber of the down servo. Even in this case, the pressure of the pressurized fluid supplied to the pressure chamber is not constant and is appropriately varied to soften the shock during gear shifting. It is difficult to accurately detect the maximum stroke amount of the actuator rod from the pressure in the pressure chamber.

This invention was made based on the above-mentioned circumstances, and
The purpose of this is to accurately determine the stroke amount of the actuator rod in a reciprocating hydraulic actuator from the pressure supplied to the pressure chamber, and to develop a friction coefficient that can control the operation of the hydraulic actuator with high precision. An object of the present invention is to provide a method for controlling the operation of a reciprocating hydraulic actuator of a coupling element.

(Means for Solving the Problems) In the method for controlling the operation of a reciprocating hydraulic actuator of the present invention, a pressure fluid whose pressure value is controlled by duty control is supplied to a pressure chamber defined by a piston in the hydraulic actuator. When the pressure in the pressure chamber is used to operate the frictional engagement element via the actuator rod linked to the piston, the switch is turned on when the actuator rod moves a predetermined distance. The corrected pressure value was obtained by correcting the pressure value of the pressure fluid supplied to the pressure chamber from the on-action of this switch according to the magnitude of its duty rate, and the corrected pressure value was obtained by integrating this corrected pressure value. When the integral pressure value reaches a predetermined value, it is determined that the stroke amount of the actuator rod has reached a predetermined stroke corresponding to the desired operation of the friction engagement element, and the supply of pressure fluid to the pressure chamber is controlled. That's what I do.

(Function) In the operation control method of the present invention, if a pressure liquid having a constant pressure value is supplied to the pressure chamber, when the integral pressure value obtained by integrating the pressure value reaches a predetermined value. This is based on the fact that the stroke amount of the actuator rod reaches a predetermined stroke and the friction engagement element performs the desired operation, and the pressure value of the pressure fluid supplied to the pressure chamber is based on duty control. Even if it fluctuates,
Regarding this fluctuation, a corrected pressure value is obtained by correcting the pressure value of the pressure liquid according to the magnitude of its duty rate, and the integrated pressure value obtained by integrating this corrected pressure value reaches a predetermined value. At this point, it is determined whether the actuator rod has reached a predetermined stroke amount, that is, whether the desired operation of the friction engagement element has been obtained.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an automatic transmission for a vehicle. In the figure, reference numeral 2 indicates an engine 2 that serves as a power source for the vehicle, and a crankshaft 4 of this engine 2 is directly connected to a pump 8 of a torque converter 6.

The torque converter 6 is connected to a case 16 via a pump 8, a turbine 10, a stator 12, and a one-way clutch 14.
is combined with The stator 12 is allowed to rotate in the same direction as the crankshaft 4 by a one-way clutch 14, but is prevented from rotating in the opposite direction.

The torque transmitted to the turbine 10 is transmitted to an input shaft 20, and from the input shaft 20 to a gear transmission 22 disposed at the rear of the input shaft 20. Here, the gear transmission 22 has a structure that achieves four forward speeds and one reverse speed.

The gear transmission 22 includes three sets of clutches 24, 26, and 28.
, two sets of brakes 30 and 32, - set of one-way clutches 34, and - set of Ravigneau-type planetary gear mechanism 36.

The planetary gear mechanism 36 includes a ring gear 38, a long pinion gear 40, a short pinion gear 42, and a carrier 48 that rotatably supports both pinion gears 40, 42 and is also rotatable. ring gear 38
is connected to the output shaft 50, and the front clutch 44 is connected to the input shaft 20 via the kickdown drum 52 and the front clutch 24. On the other hand, the rear clutch 46 is connected to the input shaft 20 via the rear clutch 26. And career 48
is connected to the case 16 via a low reverse brake 32 and a one-way clutch 34 which are arranged functionally in parallel, and via a 4-speed clutch 28 arranged at the rear end of the transmission 22. and is connected to the input shaft 20.

Here, the kickdown drum 52 can be fixedly connected to the case 16 by the kickdown brake 30.

The torque transmitted via the planetary gear mechanism 36 is transmitted to an output gear 60 fixed to the output shaft 50 so as to rotate integrally with the output shaft 50.
It is then transmitted from the output gear port 0 to the driven gear 64 via the idle gear 62, and further transmitted to the drive shaft of the drive wheels via the transfer shaft 66 and helical gear 68 fixed to the driven gear 64. 70 is transmitted to a differential gear device 72 to which the signal 70 is connected.

Each of the above-mentioned clutches and brakes, which are frictional engagement elements, is composed of a frictional engagement device equipped with an engagement piston device or a servo device, and this frictional engagement device is connected to the pump 8 of the torque converter 6. By being connected,
Oil pump driven by engine 2 (not shown)
It is operated by hydraulic pressure generated by This oil pressure is selectively supplied to each clutch and brake according to various operating conditions by a hydraulic control device, which will be described later, and the combination of operation of these clutches and brakes produces four forward speeds as shown in Table 1. One reverse gear is achieved. In Table 1, the ○ mark indicates the engagement state of each clutch or brake, and the mark ◯ indicates the engagement state of each clutch or brake. indicates that the rotation is stopped.

Table 1 Next, an electrohydraulic control device for achieving the gears shown in Table 1 in the gear transmission 22 shown in FIG. 1 will be described based on FIG. 2.

Note that FIG. 2 shows only the hydraulic control elements that operate the front clutch 24 and kickdown brake 30, respectively. Since the overall structure and operation of this electro-hydraulic control device are already known from Japanese Patent Publication No. 58-46258, etc., a description of other hydraulic control elements of the brake and clutch will be omitted.

The kickdown servo 31 is a reciprocating hydraulic actuator that controls the operation of the kickdown brake 30.
A housing defining a stepped cylinder hole 80, a stepped piston 59 slidably fitted into the stepped cylinder hole 80, and a piston rod, ie, an actuator rod, extending from the piston 59 to the outside of the housing. 79, and the tip of the actuator rod 79 can abut and engage with the kickdown brake 30, that is, the brake shoe wrapped around the kickdown drum 52. . and,
The piston 59 has first and second pressure chambers 82 and 83 defined in a stepped cylinder hole 80, and as is clear from FIG. and the stepped surface of the stepped cylinder hole 80.

A -2 shift valve 33 is connected to the first pressure chamber 81 of the kickdown servo 31 via an oil passage 35, and this 1-2 shift valve 33 further connects an oil passage 41. A speed change control valve 37 is connected thereto.

Further, an oil passage 83 is branched from the middle of the oil passage 35, and this oil passage 83 is connected to a 2-3 shift valve 84. The 2-3 shift valve 84 is further connected to two oil passages 85 and 86, one of which is connected to the second pressure chamber of the kickdown servo 31. 82, and the other oil passage 86
is connected to the front clutch 24 mentioned above.

Note that in FIG. 2, the front clutch 24 is only schematically illustrated.

Here, the -2 shift valve 33 and the 2-3 shift valve 84 are spool-type opening/closing valves that are opened and closed by the pressure supplied to the operation control port 1-87. The pressure to .88 is specifically guided from a switching valve (not shown).

For example, in the ■ speed, the spool 55 of the ■-2 shift valve 33 does not receive switching pressure through its operation control port 87, unlike the case shown in FIG. It is in a displaced state. Therefore, in this case, the oil passage 35 communicates with the oil drain port EX of the l-2 shift valve 33, and thereby the first
Pressure chamber 81 will be connected to the low pressure side. As a result, the piston 59 of the kickdown servo 31 is returned to the right in FIG. The engagement has been released.

Further, at this time, switching pressure is not supplied to the 2-3 shift valve 84 through its operation control port 88, so the spool 89 is displaced to the left end as shown in FIG. be. Therefore, in this case, the oil passage 86 passing through the front clutch 24 is connected to the 2-3 shift valve 8.
The front clutch 24 is connected to the low pressure side through the oil drain port 90 of No. 4, and thereby the front clutch 24 is disengaged. In this case, since the oil passages 85 and 86 are always in communication, the second pressure chamber 80 in the kickdown servo 31 is also connected to the low pressure side.

In addition, in the second gear, the 1-2 lift valve 33 is switched to the illustrated switching position, and the 1-2 lift valve 33 is switched to the illustrated switching position.
Shift valve 84 has also been switched to the position shown. Therefore, in this case, by supplying pressure fluid to the first pressure chamber 81 of the kickdown servo 31 through the oil passage 41.35, the piston 59, that is, the actuator rod 79, moves to the left and kicks. The down brake 30 is engaged, and the pressure fluid in the front clutch 24 can be discharged through the oil passage 86 and the oil drain port 90, thereby disengaging the front clutch 24. .

Further, in the third gear, the 1-2 shift valve 33 remains in the illustrated switching position;
The shift valve 84 is in the switching position where its spool is moved to the right, and thereby the oil passages 83 and 85, 86
is communicated with through the 2-3 shift valve 84, and its oil drain port 90 is closed. in this case,
Pressure fluid supplied to the oil passage 83 through the 1-2 shift valve 33 is supplied to the front clutch 24 through the 2-3 shift valve 84 and through the oil passage 86.
This brings the front clutch 24 into an engaged state.

On the other hand, in the kickdown servo 31, the oil passages 86, 85 are always in communication, so the pressure fluid supplied to the front clutch 24 is also supplied to its second pressure chamber 82, and At the same time, the same pressure liquid is also supplied to the first pressure chamber 81 through the oil passage 35. In this case, since the piston 59 of the kickdown servo 31 is a stepped piston as described above, due to the difference in the pressure receiving area at both ends, the piston 59 is connected to the actuator rod 7.
9 to the right, thereby causing the kickdown brake 30 to be disengaged.

Further, when the gear stage is shifted from 3rd speed to 2nd speed, each of the -2 shift valve 33 and the 2-3 shift valve 84 is at the switching position shown in the figure, and in this case, the kickdown servo 31 , by supplying pressure fluid to the first pressure chamber 81, the piston 59, that is, the actuator rod 79, is displaced in the direction of engaging the kickdown brake 30, while the front clutch 24 Oil line 86.2-3 shift valve 84 and oil drain port 9
By letting the pressure fluid escape through 0, the engagement is released, but at this time, the front clutch 24
Disengagement is performed by the kickdown servo 31 as described later.
When the piston 59 of is displaced, its second pressure chamber 82
It is designed to be controlled by the back pressure generated by the

Therefore, in order to generate appropriate back pressure in the second pressure chamber 82, a predetermined throttle 91 is provided in the oil drain port 90 of the 2-3 shift valve 84, and 8
4 is also provided with a predetermined throttle 92.

As shown in Fig. υ, the above-mentioned speed change control valve 37 has
An oil passage 61 is located at the left end thereof, and an oil passage 63 is also connected thereto. The oil passage 61 is connected to the oil pump described above, and there are
A solenoid valve 67 is inserted to open and close this oil passage 61 and to control the pressure of the pressure fluid supplied through the speed change control valve 37. This solenoid valve 67 is electrically connected to an electronic control unit (ECU) 65, and this electronic control unit 65 controls the switching operation of the solenoid valve 67 through duty control. Further, the oil passage 63 is also supplied with working oil pressure regulated to a predetermined pressure from the aforementioned oil pump. The pressure fluid in the oil passage 61 is discharged to the low pressure side via the electromagnetic valve 67 which is opened and closed according to the duty rate. Therefore, the hydraulic pressure according to the duty rate is applied to the left end surface of the spool 69 of the speed change control valve 37. It will work. As a result, the speed change control valve 37 regulates the oil pressure from the oil passage 63, and the oil pressure P shown by the broken line in FIG.
KD will be generated in the oil passage 41.

The electronic control device 65 not only controls the opening and closing of the solenoid valve 67 but also has a built-in shift command output device that outputs a shift command based on the driving state of the vehicle. In order to detect the driving state of the vehicle, signals from various sensors or detection devices are input.

For example, these sensors or detection devices include an engine rotation speed sensor that detects the rotation speed of the engine 2, a throttle valve opening sensor 103 that detects the throttle valve opening θ of the engine 2, and a throttle valve opening sensor 103 that detects the rotation speed NT of the input shaft 20. The input shaft speed sensor 101 detects the rotation speed NO of the output shaft 50 corresponding to the vehicle speed.
an output shaft speed sensor 144 of the driven gear 64 provided to detect the temperature of the lubricating oil;
There are select lever selection position detection switches, auxiliary switch selection position detection devices, etc.

Further, in this embodiment, a signal from a kickdown switch 93 built into the kickdown servo 31 is also input to the electronic control device 65. This kickdown switch 93 is operated by moving the piston 59 to the left in FIG. When moved to the reference position, a signal is output to the electronic control unit 65.

In FIG. 2, among the sensors and detection devices input to the electronic control device 65, the input shaft speed sensor 101, the throttle valve opening sensor 103, and the output shaft speed sensor 144
, and only the kickdown switch 93 are shown.

Next, 3-2 is carried out by the electronic control device 65 mentioned above.
The downshift routine will be described with reference to the flowcharts of FIGS. 3A, 3B, and 3C, and the graphs shown in FIGS. 4 to 6, respectively.

First, the 3-2 downshift routine is repeatedly executed in a predetermined control cycle, for example, every 20m5ec, and when this routine is executed, the automatic transmission is in 3rd gear. is in gear. Therefore, in this case, as is clear from Table 1 above,
The kickdown brake 31 is in a disengaged state, whereas the front clutch 24 is in an engaged state.

In the flowchart of FIG. 3A, in step S1, it is determined whether a 3-2 shift command has been generated from the speed change command output device. Here, the shift command output device is a fourth
Based on the broken 3-2 shift line shown in the figure, a 3-2 shift command is output in consideration of the vehicle speed and throttle valve opening. In addition, in FIG. 4, the solid line indicates the 2-3 shift line.

If the determination in step S1 is negative (No), the process proceeds to step Sll, in which the duty rate of the solenoid valve 67 is set to 0, and the timer TD is reset to 0, and the process proceeds to step S1. return.

If the determination in step Sl is positive (Yes), in step S2, the input shaft speed sensor 101
The rotational speed NT of the output shaft and the rotational speed NO of the output shaft are read from the output shaft speed sensor 144.

Also, when the determination in step St becomes positive, the fifth
As shown in the figure, the duty rate of the solenoid valve 67 is D
uO, thereby generating the hydraulic pressure PKD having a pressure value corresponding to the duty rate DuO.

When the oil pressure PKD is generated in the oil passage 41 as described above, this oil pressure is supplied to the first pressure chamber 81 of the kickdown servo 3 through the 1-2 shift valve 33 and the oil passage 35 which are in the open state. As a result, the pressure within the first pressure chamber 81 is increased. Since the pressure in the first pressure chamber 81 moves the piston 59 to the left in FIG. 2 against the spring force of the compression coil spring 57, the actuator rod 79 also moves in conjunction with the piston 59. The kickdown brake 30 is moved to the left, and the kickdown brake 30 begins to tighten the kickdown drum 52.

After step S2, step S3 is executed, but
Here, kick down switch (KD switch) 93
In other words, whether a signal is output from the KD switch 9
3, it is determined whether or not the switch is turned on. Immediately after the routine from step S1 is executed, the kickdown servo 31 has not yet been activated, so the determination here is negative, and in the next step S4, the integral pressure value AP is After is set, the process advances to step S5.

In step S5, the rotation speed NT of the human power shaft 20 is 1.2N.
It is determined whether or not the value is O or more. Here, NO is the output shaft rotation speed.

Again, immediately after starting this routine, the determination in step S5 is negative, so the process advances to step S6.
In this step S6, the duty rate of the solenoid valve 67 is controlled based on open loop control. Here, the open loop control of the duty rate is performed according to the duty rate change characteristic shown in FIG. That is, at the time when the 3-2 shift command is output, the duty rate is set to DuO instead of 0 as described above, and after the predetermined time TI has elapsed, the duty rate becomes a value larger than DuO. It is gradually increased after being changed to Dul. Then, as shown in FIG. 5, the input shaft rotation speed NT is higher by a predetermined value (for example, 35 rpm) than the rotation speed NTO of the input shaft 20 at the time the 32 shift command is output. When reaching , the duty rate becomes several percent d (for example, 5%).
After that, it is gradually increased for a predetermined time T2, then it is increased by several percentage points d, and then it is gradually decreased.

When the duty rate of the electromagnetic valve 67 is controlled according to the above-mentioned characteristics, that is, when the duty rate is controlled not from 0 but from DuO, increases after a predetermined period of time, and thereafter increases or decreases. , the stroke time of the piston 59 of the kickdown servo 31 is effectively utilized and its displacement speed is optimally controlled.

That is, when the duty rate is θ, as is clear from FIG. 6, a high pressure is built up in the first pressure chamber 81 of the kickdown servo 31, so the piston 59 is
It tries to move rapidly to the left in Fig. 2. In this way, if the moving speed of the piston 59 is fast, the 2-3 shift valve 84
Since the oil drain port 90 is provided with the throttle 91 as described above, the back pressure in the second pressure chamber 82 is increased. Here, the second pressure chamber 82 is in constant communication via the oil passages 85 and 86, so when the back pressure in the second pressure chamber 82 is high, this back pressure is caused by the pressure from the front clutch 24. Pressure fluid can escape to the oil drain port 90 via the oil passage 86.2-3 shift valve 84, and as a result, the disengagement of the front clutch 24 is delayed, and the input rotational speed NT does not rise. There is a possibility that the kickdown brake 30 may be engaged.

However, as mentioned above, in this embodiment, 3-
At the same time as the 2nd shift command is output, the duty rate of the solenoid valve 67 is increased to DuO, and then the duty rate of the solenoid valve 67 is increased to DuO for a predetermined period of time T1.
After the passage of , Dul is increased without any measure, and even after this, it is gradually increased, so the piston 5
By suppressing the stroke speed of 9, it is possible to suppress an increase in back pressure in the second pressure chamber 82. As a result, the pressure fluid from the front clutch 24 can be effectively escaped.
The engagement of the front clutch 24 begins to disengage well, and the second
The back pressure in the pressure chamber 82 will be used to control the rotation speed of the input shaft 20 during feedback control, which will be described later. From the time when the front clutch 24 starts to slip, the rotational speed N of the input shaft 20 is increased as shown in FIG.
T will begin to rise. That is, at this point, the shift from the third speed to the second speed is started. At this time, if the duty rate of the solenoid valve 67 continues to increase further from Dul, there is a risk that the rotation of the input shaft 20 will increase too rapidly. Therefore, after this, as is clear from the duty rate control characteristics in FIG. By restricting the escape of pressure fluid from the clutch 24, it is possible to effectively control the disengaged state of the front clutch 24, thereby suppressing a sudden increase in rotation of the input shaft 20 and optimizing its rotation. can be raised. In addition, in the duty rate control described above, a 3-2 shift command is output for a predetermined time T.
1, the duty rate is maintained at DuO, which is a relatively low value, so for a while after this duty control is started in an open loop, the kickdown servo 3
A relatively high hydraulic pressure can be continued to be supplied to the first pressure chamber 81 of the first pressure chamber 81, and thereby the stroke speed of the piston 59, that is, the actuator rod 79, will not undesirably decrease.

When step S6 described above is executed, the process returns to step S1 and the steps from step S1 are repeated. Therefore, step S6 is repeated until the judgment in step S5 is positive. When the piston 59 of the kickdown servo 31 is displaced to the above-mentioned reference position while the execution in step S6 is being repeated, the KD switch 93 is turned on, and as a result, the step S3 is executed. At this point, the determination in step S7 is positive, and step S7 is executed. In step S7, a routine for determining the stroke amount of the actuator door 9 in the kickdown servo 31 is executed, the details of which are shown in the flowchart of FIG. 3C.

In FIG. 3C, in step S71, a corrected oil pressure value PKDn corresponding to the current duty rate of the solenoid valve 67 is added to the current integral pressure value AP, and the added value or the new integral pressure value is added. Assigned to AP. Here, the corrected hydraulic pressure value P KDn is determined from the correction characteristic shown by the solid line obtained by correcting the characteristic shown by the broken line in FIG. This correction characteristic is such that in an area where the duty rate is small, the corrected oil pressure value PKDn is lower than the actual oil pressure value PKD, and conversely, in an area where the duty rate is large, it is lower than the actual oil pressure value PKD. The corrected oil pressure value PKDn is set to be high.

Proceeding from step S71 to the next step S72, in this step S72, the newly determined integral pressure value AP
It is determined whether or not a predetermined value XAP or more has been reached. Here, the predetermined value XAP is the stroke of the actuator rod 79 in the kickdowner 31 after the KD switch 93 is turned on when the duty rate is continued to be set to the reference duty rate DUS shown in FIG. reaches a predetermined stroke, for example, the maximum stroke in this embodiment, and until the brake shoe of the kickdown brake 30 is completely tightened to the kickdown drum 52, the first pressure chamber 81 of the kickdown servo 31 This corresponds to the integral value obtained by adding the reference oil pressure PKDS supplied to the PKDS every 20m5ec. And kickdown servo 31
The oil pressure supplied to the first pressure chamber 81 or the reference oil pressure PKD
If it is different from S, the stroke amount can be detected accurately by correcting this oil pressure to the corrected oil pressure value PKDN shown by the solid line in FIG. This correction is to correct the leakage of hydraulic oil from the first pressure chamber 81 of the kickdown servo 31, and the higher the oil pressure, the greater the leakage amount, and the corrected oil pressure value PKDN is smaller than the oil pressure PKD. set to the value.

In this invention, the characteristic shown by the broken line in FIG. 6 is corrected to resemble the correction characteristic shown by the solid line to solve the above-mentioned problem. Therefore, the integral pressure value AP can be determined from the correction characteristic. By calculating using the corrected pressure value PKDn, the integral pressure value AP can be calculated using the kickdown servo 3.
The pressure in the first pressure chamber 81 at 1 is exactly equal to the pressure in the first pressure chamber 81 at 1. Therefore, this integral pressure value AP and the predetermined value XA
By comparing P in step S72, it is possible to accurately detect whether the piston 59, that is, the actuator rod 79 has reached its maximum stroke. In other words, it is possible to accurately detect the point in time when the shift from third speed to second speed is substantially completed.

If the determination in step 372 is negative, that is, if the actuator rod 79 has not yet reached its maximum stroke, the process advances to step S73, in which the flag FLGS is set to 0, and then the stroke amount is determined. The routine returns to step S5, and the steps after step S5 are repeated.

Here, after the KD switch 93 is turned on,
While the determination in step S5 is negative, steps S7 and S5
and the path steps through S6 are repeated. However, if the determination in step S5 is positive,
The steps after step S8 will be executed, but even in this case, since the determination in step S3 is positive, the stroke amount determination routine in step S7 described above will be repeated. Become.

Therefore, as is clear from the flowchart in FIG. 3C, after the KD switch 93 is turned on, step S71 is repeatedly executed, so that the integrated pressure value AP is changed to the corrected pressure value P at that time. KDn will continue to be added. Then, the integral pressure value AP is a predetermined value
When AP or more is reached and the determination in step S72 is positive, step S74 is executed for the first time, and the flag FLGS is set to 1, and then the process returns to step S5. Here, setting the flag FLGS to 1 means that the actuator rod 79 has reached its maximum stroke, as is clear from the above explanation, and this point is indicated by the symbol SE in FIG. It is shown with .

By the way, at the same time that the stroke amount determination routine in step S7 described above is executed, the steps after step S8 are also executed sequentially via step S5. First, in step S8, the flag FLGS is set to 1. It is determined whether or not there is one. Here, immediately after the determination in step S5 becomes positive for the first time and the steps after step S8 are executed, step S74 is still being executed in the stroke amount determination routine in step S7. , since step S8 is reached after step S73 is executed, the determination in step S8 is negative. Therefore, in this case, step SIO is executed bypassing step S9, and in this step SIO, it is determined whether the value of the timer TD mentioned above has reached a predetermined time XTD or more. Here, since the timer TD remains set to 0 as described above, the determination in this case is negative, and therefore, in step S12, a feedback control routine for controlling the duty rate of the solenoid valve 67 is executed. be done. That is, as is clear from the above description and FIG. , starts slightly before the rotational speed NT of the input shaft 20 is synchronized.

In the feedback control routine, as shown in FIG. 5, until the rotational speed NT of the input shaft 20 reaches a set value that is lower by a predetermined amount α from the target rotational speed, the rate of change of the rotational speed or ΔNil is determined. When the duty rate of the solenoid valve 67 is controlled so that the rotation speed NT is between the set value and the target rotation speed, the rate of change is expressed as ΔNi
Further, when the rotational speed NT exceeds the set value, the duty rate of the solenoid valve 67 is controlled so that the rate of change becomes a negative value. By such feedback control of the duty rate, the rotation speed NT of the human power shaft 20 quickly and accurately matches the target rotation speed,
And it will be maintained.

On the other hand, even while the above-described feedback control routine is being executed, the stroke determination routine in step S7 is being executed continuously, so when the time point SE in FIG. 5 is reached, as described above, If the determination in step S72 is positive, the piston 59 of the kickdown servo 31, that is, the actuator rod 79 reaches its maximum stroke. Therefore, at this point, the kickdown brake 30 is in a stopped state, while the front clutch 24 is disengaged, and as a result,
A shift from 3rd speed to 2nd speed is achieved. After this, step S
The process advances from step S72 to step S74, and in this case, the flag FLGS is set to 1 in step S74.

After the flag FLGS is set to 1, step S8
When the subsequent steps are executed, unlike the case described above, the determination in step S8 is positive, so in this case, the next step S9 is executed. This step S
9, timer TD is set, i.e. timer TD
is activated and the timer TD starts measuring elapsed time, and at the same time, the flag FLGS is reset to O and the process proceeds to the next step SIO. In this step SlO, as described above, the value of the timer TD is set to the predetermined value
It is determined whether or not TD has been reached, but since this is immediately after time measurement by timer TD has started, the determination is negative and the above-described feedback control routine is executed. However, after this, when the value of timer TD is added and the value exceeds the predetermined value XTD,
Since the determination in step SlO is positive, the execution of the feedback control routine in step 312 is subsequently stopped, step Sll is executed, and the duty rate of the solenoid valve 67 is set to O. ,
Timer TD is also reset to 0, which completes the 3-2 downshift routine.

Note that the above-mentioned predetermined value XTD is the kickdown servo 31.
The machining accuracy and assembly of the piston 59 in this process are set to compensate for the accuracy.

This invention is not limited to the one embodiment described above, and various modifications are possible. For example, in one embodiment:
Although the frictional engagement element has been explained with reference to a kickdown brake, it is of course applicable not only to brakes such as this kickdown brake, but also to reciprocating hydraulic actuators that actuate clutches such as a front 4° clutch. It is.

(Effects of the Invention) As explained above, according to the reciprocating hydraulic actuator of the present invention, pressure fluid whose pressure value or duty is controlled is supplied to the pressure chamber, and the actuator is moved. At this time, the stroke amount of the actuator rod can be determined based on the integrated pressure value obtained by integrating the value of the oil pressure supplied to the pressure chamber from the time when the switch is turned on, without using any sensor means or the like. Here, when calculating the integral pressure value, the hydraulic pressure value is not a value determined based on duty control, but a corrected pressure value that is corrected according to the magnitude of the duty rate. Therefore, the calculation of the integral pressure value accurately matches the actual pressure in the pressure chamber, and as a result, the stroke amount of the actuator rod can be detected with high precision, and from this, the operation of the frictional engagement element can also be accurately detected. It has excellent effects such as being able to control the

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a schematic configuration diagram of a vehicle automatic transmission, FIG. 2 is a hydraulic circuit diagram around the kickdown servo and front clutch, and FIG.
3B and 3C are flow charts showing a 3-2 downshift routine in an automatic transmission, and FIG.
Figure 5, a graph of the 3-2 shift line determined based on the relationship between vehicle speed and throttle valve opening, shows changes in duty rate, input shaft rotational speed, and input shaft rotational speed change rate with respect to time. The graph shown in FIG. 6 is a graph showing the relationship between duty rate and oil pressure. 30...Kickdown brake, 3I.Kickdown servo (hydraulic actuator), 52...Kickdown drum, 59...Piston, 65...Electronic control unit, 6
7... Solenoid valve, 79... Actuator rod, 8
1...1st pressure chamber, 93...kick down switch. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kanji Nagato Fig. 2 Fig. 3A Fig. 3B Fig. 3C Fig. 4 Fig. 6

Claims (1)

[Claims] In a reciprocating hydraulic actuator that is combined with a frictional engagement element built into a vehicle automatic transmission and used for shifting gears, and operates this frictional engagement element,
Pressure fluid whose pressure value is controlled by duty control is supplied to the pressure chamber defined by the piston in this hydraulic actuator to raise the pressure in the pressure chamber, and the actuator rod is linked to the piston by the pressure in the pressure chamber. When actuating the frictional engagement element via the actuator rod, the switch is turned on when the actuator rod moves a predetermined distance, and the pressure value of the pressure fluid supplied to the pressure chamber is determined by the duty. A corrected pressure value is obtained by correcting according to the magnitude of the ratio, and when the integrated pressure value obtained by integrating this corrected pressure value reaches a predetermined value, the stroke amount of the actuator rod reaches the desired value of the frictional engagement element. A method for controlling the operation of a reciprocating hydraulic actuator for a frictional engagement element, characterized in that the supply of pressure fluid to the pressure chamber is controlled by determining that a predetermined stroke corresponding to the operation has been reached.