JPH04290670A - Automotive hydraulic controller of automatic transmission - Google Patents

Abstract

PURPOSE:To reduce the speed change shock, in the speed change operation by an automatic transmission for vehicle. CONSTITUTION:At the spool 31 of a discharged oil control valve 29 for carrying out the pressure discharge for the fourth speed clutch 18, the first rand 31a on which the pressure discharge of the fourth speed clutch 18 can act in the direction for the shift of the spool 31 to the pressure discharge state, second rand 31b on which the pressure discharge of the third speed clutch 17 acts in the same direction, and the third rand 31c on which the pressure discharge of the second speed clutch 16 can act are installed. During the speed change operation, the spool 31 is driven in the valve opening direction in the adjusted pressure state corresponding to the reduction of the engagement pressure of the fourth speed clutch 18 and the increase of the engagement pressure of the speed change stage (second speed or third speed), and the pressure discharge of the fourth speed clutch 18 is carried out.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for a vehicle automatic transmission for automatically hydraulically controlling the speed change of an automatic transmission suitable for use in a vehicle such as an automobile.

0002

[Prior Art] Conventionally, some automobiles use automatic transmissions that perform gear shifting operations under hydraulic control. There are known devices that automatically shift gears based on predetermined shift characteristics. In an automatic transmission with the above structure, when performing a downshift operation such as kickdown by depressing the accelerator pedal from a high speed gear to a low speed gear, the engine speed is changed according to the gear ratio of the low speed gear. By increasing the torque to an appropriate level and synchronizing the gears that mesh with each other, shocks caused by torque fluctuations can be alleviated. For example, as disclosed in Japanese Patent Application Laid-Open No. 61-84450,
In order to exhaust the pressure of the hydraulic engagement element for high speed gear to establish gear transmission for high speed gear, the supply pressure of the hydraulic engagement element for low speed gear to establish gear transmission for low speed gear is predetermined. There are known oil drain control valves that switch to open the oil drain path for performing the above-mentioned drain pressure when a value is reached.

[0003] In the automatic transmission having the above structure, for example, when shifting from the high-speed fourth gear to the low-speed second gear by kickdown, the hydraulic engagement for the high-speed gear is used. The engagement pressure P4 of the 4-speed clutch as an element changes as shown by the imaginary line in the upper part of FIG. At this time, the initial pressure reduction of the engagement pressure P4 is performed relatively gently via a fixed orifice such as a throttle provided in the oil drainage path of the 4th speed clutch, and the subsequent pressure reduction is also achieved through a fixed orifice provided in the oil drainage path of the 4th speed clutch. Since the pressure in the accumulator for mitigating the clutch engagement shock is exhausted, the process is performed relatively slowly. Then, in response to an increase in the engagement pressure P2 of the second-speed clutch acting on the land of the valve body, the valve body, which is biased by the spring toward the side that closes the oil drain passage, moves against the biasing force. , the oil drain control valve opens (a in the figure). That is, since oil is drained from the oil drain control valve in addition to the fixed orifice, the pipe resistance due to oil drain resistance etc. is reduced, and the engagement pressure P4 of the 4th speed clutch decreases relatively suddenly from the time the valve is opened. The pressure will be completely evacuated.

[0004] In this way, the engagement pressure P2 of both clutches is
- Although P4 is supplied and discharged, the engine speed also changes in accordance with these changes, as shown by the imaginary line in the middle of FIG. At the beginning of the gear shift, the engine speed rises slowly, but this is because, as mentioned above, the pressure from the 4th gear clutch is gradually released, and a certain amount of torque is transmitted depending on the engaged state of the 4th gear. This is because Thereafter, the engagement force of the 4-speed clutch decreases in accordance with the exhaust pressure of the 4-speed clutch, and as described above, the oil drain control valve opens due to switching, and the 4-speed clutch is opened.
Since the engagement pressure of the fast clutch rapidly decreases, the engine speed rapidly increases. In addition, the vehicle body acceleration G also changes from negative acceleration as shown by the imaginary line in the lower part of the figure, because the engagement pressure of the 4th speed clutch rapidly decreases and the engagement pressure of the 2nd speed clutch rapidly increases. There has been a problem in that the acceleration changes violently to a positive value, and the occupants feel a shift shock due to this change.

[0005]

[Problems to be Solved by the Invention] In view of the problems of the prior art, the main object of the present invention is to reduce the shift shock when downshifting is performed by depressing the accelerator pedal. An object of the present invention is to provide an improved hydraulic control device for a vehicle automatic transmission.

[0006]

[Means for Solving the Problems] According to the present invention, such an object is achieved by switching between a plurality of gears by supplying pressure to one of both hydraulic engagement elements for high and low speeds and discharging pressure from the other. A hydraulic control device for an automatic transmission for a vehicle, which is capable of selectively opening and closing an oil drain passage of a hydraulic engagement element for a high speed gear, and has a valve body elastically biased in the closing direction. an oil drain control valve; first and second pressure-receiving surfaces provided on the valve body to apply hydraulic pressure to move the valve body in a direction to open the oil drain path against the biasing force; During a shift operation from a high speed gear to a low speed gear, the exhaust pressure of the hydraulic engagement element for the high speed gear is applied to the first pressure receiving surface, and at the same time, the exhaust pressure of the hydraulic engagement element for the low speed gear is applied to the first pressure receiving surface. This is achieved by providing a hydraulic control device for an automatic transmission for a vehicle, characterized in that supply pressure is applied to the second pressure receiving surface.

[0007]

[Operation] By doing this, when the accelerator pedal is depressed and the downshift is performed, both the exhaust pressure from the high-speed gear hydraulic engagement element and the supply pressure to the low-speed gear hydraulic engagement element are released. is used to move the valve body of the oil drain control valve to change the pipe resistance (oil drain resistance, throttle, etc.) of the oil drain line of the hydraulic engagement element for high speed gears. The valve body is quickly moved by the large exhaust pressure from the high-speed hydraulic engagement element, and in the latter half of the gear shift, the exhaust pressure from the high-speed hydraulic engagement element decreases, but the low-speed hydraulic engagement element The valve body can be moved by increasing the supply pressure of the coupling element. Therefore, the pressure from the high-speed gear hydraulic engagement element can be quickly discharged at the initial stage of gear shifting.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an outline of an automatic transmission for an automobile to which the present invention is applied. In FIG. 1, an automatic transmission 2 is connected to an engine 1, and the automatic transmission 2 includes a torque converter 3 with a lock-up clutch and a gear transmission 4 with, for example, a hold clutch and 4 forward speeds and 1 reverse speed. is built-in. A ring gear of a differential device 6 connected to the drive wheels 5 is engaged with the final drive gear 4a of the gear transmission 4, and the engine 1
The output torque is transmitted to the drive wheels 5 via the torque converter 3 and the gear transmission 4.

Each gear stage of the automatic transmission 2 is controlled to change automatically by a control unit 7 serving as an automatic shift control means in accordance with a vehicle speed signal and a throttle opening signal as an engine load. . The control unit 7 consists of a combination of general circuits,
It has a PU, ROM, RAM, and input/output circuits 7a and 7b. The input circuit 7a includes a final drive gear 4a.
For example, a pulse signal is input as a vehicle speed signal from a vehicle speed sensor 8 provided nearby, and a voltage signal, for example, is input as a throttle opening signal from a throttle opening sensor 9 attached to a throttle body (not shown) of the engine 1. has been done. The input circuit 7a receives, for example, air conditioner and cooling water temperature signals from various signal sensors 10 for use as conditions for speed change control.

Within the control unit 7, map control of speed change is performed using the CPU, ROM, and RAM in accordance with each signal input to the input circuit 7a. The output circuit 7b of the control unit 7 outputs a shift control signal and a lockup control signal to each solenoid valve SV such as a shift control and a lockup control of the hydraulic control circuit 11. This hydraulic control circuit 11 automatically switches the gears of each gear of the automatic transmission 2.
Moreover, the engagement state of the lock-up clutch is controlled.

The gear transmission 4 is, for example, of a constant mesh type, and has an input shaft 12, an output shaft 13, and a counter shaft 14 that are parallel to each other. The input shaft 12 is a counter shaft 14 gear-coupled via an idle gear.
is provided with a first speed clutch 15 for establishing the first speed and a second speed clutch 16 for establishing the second speed, and the input shaft 12 is provided with a first speed clutch 15 for establishing the second speed. for 3
A speed clutch 17 and a four-speed clutch 18 for establishing the fourth speed are provided. Further, the output shaft 13 is provided with a one-way clutch 19 connected to the first speed gear so as to allow over-rotation on the output shaft 13 side. torque cannot be transmitted. Therefore, when another gear stage is established, torque is transmitted to the output shaft 13 without going through the one-way clutch 19. Further, a hold clutch LH is provided in parallel with the one-way clutch 19,
When the hold clutch LH is engaged, the one-way clutch 19 is bypassed and torque is transmitted via the hold clutch LH.

FIG. 2 is a schematic hydraulic circuit diagram showing the main parts of the hydraulic control circuit 11 to which the present invention is applied. In the figure, a supply/discharge port 18a to the oil chamber of the 4-speed clutch 18 and a first port 20a of the manual valve 20 communicate with each other via a first oil passage 21. This manual valve 20 is
The spool 22 can be moved in the left-right direction in the figure, and the figure shows a state in which the D range, in which the gears can be automatically changed from the first gear to the fourth gear, is selected. In the illustrated state, the second port 20b of the manual valve 20 communicates with the first port 20a via the outer circumferential groove of the spool 22.
The second oil passage 2 is connected to the first port 23a of the 3-4 shift valve 23.
They are connected via 4. The spool 25 of the 3-4 shift valve 23 is resiliently biased toward the right in the figure by a spring 26. The figure shows a state in which the second gear, which is a low speed gear, is selected after traveling in the fourth gear, which is a high speed gear. In this second gear selection state, the side opposite to the spring 26 is Hydraulic oil is not supplied to the oil chamber from the second port 23b via a control valve (not shown), and the spool 25
is biased toward the right as shown in the figure.

The spool 25 of the 3-4 shift valve 23 has a third port 2 which communicates with the first port 23a through the outer circumferential groove of the spool 25 when the second gear stage is selected.
3c is provided, and a first oil drain passage 27 that is open to the atmosphere is connected to the third port 23c via a fixed orifice 28. Therefore, in the illustrated state, the pressure of the 4-speed clutch 18 is drained via the fixed orifice 28 of the first oil drain path 27.

Fixed orifice 28 of the first oil drain path 27
A branch path 27 a branched from an intermediate portion in front of the drain oil control valve 29 is connected to a first input port 29 a of the drain oil control valve 29 . Due to the exhaust pressure supplied to the first input port 29a, the spool 31, which is biased by the spring 30 toward the left in the drawing of the drain oil control valve 29, is directed toward the right against the biasing force of the spring. In order to move the spool 31, the exhaust pressure supplied to the first input port 29a is applied to the first land 31a of the spool 31. Further, the drain oil control valve 29 is provided with second to fourth input ports 29b to 29d, and the second input port 29b is connected to the supply/discharge port 1 to the oil chamber of the 3rd speed clutch 17.
7a is connected via a third oil passage 32, and a supply/discharge port 16a to the oil chamber of the second speed clutch 16 is connected to the third input port 29c via a fourth oil passage 33. ,
The second and third lands 31b and 31c of the spool 31 are moved so that the spool 31 is moved against the spring biasing force by the exhaust pressure selectively supplied to each port 29b and 29c.
The exhaust pressure supplied to each port 29b and 29c is applied to the exhaust pressure.

A sub-branch passage 27b further branched from the branch passage 27a is connected to a fourth input port 29d of the drain oil control valve 29.
By applying appropriate exhaust pressure to each of the lands 30a, 30b, and 30c, the spool 31 moves toward the right in the figure against the biasing force of the spring 30. An oil drain port 34 is provided which communicates with the fourth input port 29d through the outer circumferential groove of the spool 31 when the spool 31 moves.

Note that the fourth port 23 of the 3-4 shift valve 23
A branch path 32a branched from the third oil path 32 connected to the supply/discharge port 17a of the third-speed clutch 17 is connected to d. The 3-4 shift valve 23 is provided with a fifth port 23e that communicates with the fourth port 23d via the outer peripheral groove of the spool 25 in the illustrated state, and a fifth port 23e connected to the fifth port 23e. The oil passage 35 is selectively connected via a 2-3 shift valve 38 to a second oil drain passage 37 that is open to the atmosphere via a fixed orifice 36 . Further, an oil supply path 39 connected to a hydraulic pump (not shown) is selectively connected to a branch path 33a branched from the fourth oil path 33 via a 2-3 shift valve 38. There is.

In the hydraulic control circuit configured in this manner, when downshifting from the fourth gear to the second gear, the engagement hydraulic pressure in the hydraulic chamber of the fourth gear clutch 18 is discharged. Shift the clutch from the engaged state to the released state. As described above, this exhaust pressure is discharged through the first oil discharge passage 27 due to the communication state between the first and third ports 23a and 23c of the 3-4 shift valve 23, and in the initial stage, the fixed orifice The exhaust pressure is discharged through the branch passage 27.
a to the first input port 29a of the drain oil control valve 29 and acts on the first land 31a.
The spool 31 begins to move to the right in the figure against the force of firing. At this time, as described above, due to the operation of the 2-3 shift valve 38, hydraulic pressure is applied to the hydraulic chamber of the 2nd speed clutch 16, and the 2nd speed clutch 16 becomes engaged. It also acts on the third land 31c via the third input port 29c. The increases and decreases in both oil pressures in this case change as shown by the clutch oil pressure line P4 showing the discharge pressure of the 4th speed clutch 18 and the clutch oil pressure line P2 showing the supply pressure of the 2nd speed clutch 16 in the upper part of FIG. do.

According to the present invention, the driving force F in the direction of opening the oil drain port 34 to the spool 31 of the oil drain control valve 29, which is switched to discharge pressure from the 4-speed clutch 18, is equal to the exhaust pressure P4 of the 4-speed clutch 18. The first land 2 receives the pressure from
9a multiplied by the area Sa of the second-speed clutch 16 and the supply pressure P2 of the second-speed clutch 16 multiplied by the area Sb of the second land that receives the pressure (F=P4・Sa+P
2.Sb). Then, when the driving force F becomes larger than the spring force of the spring 30 that urges the spool 31 in a direction to close the oil drain port 34, the fourth input port 29d and the oil drain port 34 communicate with each other. The oil from the 4th speed clutch 18 is largely drained.

Immediately after the start of the shift operation, the engagement oil pressure of the 2nd speed clutch 16 on the low speed side is low, and the exhaust pressure of the 4th speed clutch 18 on the high speed side, which has been engaged so far, is low. Because the spool 31 is moved in the valve opening direction by the high pressure generated by
In contrast to the valve opening operation after waiting for the engagement oil pressure to rise, the valve opening is performed extremely rapidly. Therefore, as shown in the upper part of FIG. 3, the engagement oil pressure of the fourth-speed clutch 18 on the high-speed gear side is rapidly reduced with respect to the exhaust pressure curve shown by the imaginary line of the conventional example. Then, corresponding to the ratio of the respective areas Sa and Sb of the first land 29a and the second land 29b,
The pressure of the fourth speed clutch 18 is reduced in response to the pressure increase of the speed clutch 16, and by appropriately setting the area ratio, the driving force F can be kept approximately constant.

In this manner, the oil drain control valve 29 operates while the pressure is regulated, so that the clutch engagement oil pressure changes relatively smoothly as shown in FIG. 3. Therefore,
This is due to an increase in the transmission torque on the low speed gear side due to an increase in the engagement oil pressure of the clutch on the low speed gear side, and a decrease in the transmission torque on the high speed gear side due to a decrease in the engagement oil pressure of the high speed gear side clutch. The change in the transmitted torque during the shift process is small, the change in the vehicle body acceleration G shown in the lower part of FIG. 3 is small, and the shock during the shift is extremely small. When the force in the valve opening direction on the spool 31 due to the engagement hydraulic pressure of the 2nd speed clutch 16 overcomes the biasing force of the spring 30, the valve opens only by the engagement hydraulic pressure of the 2nd speed clutch 16, and the 4th speed clutch 18 engagement hydraulic pressure is completely exhausted.

In the above embodiment, the downshift from 4th gear to 2nd gear was shown, but the same applies to other gears. For example, when downshifting from 4th gear to 3rd gear, The 2-3 shift valve 38 switches, the oil supply path 39 and the fifth oil path 35 communicate with each other, and the engagement oil pressure of the 3rd speed clutch 17 can increase. This 3 speed clutch 17
The engagement hydraulic pressure is applied to the second port 2 of the oil drain control valve 29.
9b and acts on the second land of the spool 31. Therefore, at the beginning of gear shifting, the drain oil control valve 29 is quickly opened by the exhaust pressure of the 4th speed clutch 18, and even if the exhaust pressure decreases, the valve is opened due to the increase in the engagement oil pressure of the 3rd speed clutch 17. continues, and smooth gear shifting is performed in the same way as above.

[0022]

Effects of the Invention As is clear from the above explanation, according to the hydraulic control device according to the present invention, pressure is supplied to the hydraulic engagement element for the low speed gear during the shift operation from the high speed gear to the low speed gear. The valve body driving force in the valve opening direction, which changes relatively smoothly by combining the rise and fall of both hydraulic pressures due to the exhaust pressure of the high-speed stage hydraulic engagement element and the exhaust pressure of the high-speed stage hydraulic engagement element, causes the oil drain control valve to open. Since the hydraulic engagement element for high-speed gears is controlled to exhaust pressure, changes in the exhaust pressure can be alleviated, reducing gear shock during downshifts such as kickdowns, and improving gear shifting. The quality during operation can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an overview of an automatic transmission for an automobile to which the present invention is applied.

FIG. 2 is a schematic hydraulic circuit diagram showing main parts of a hydraulic control device for an automatic transmission of an automobile to which the present invention is applied.

FIG. 3 is a diagram illustrating an operation during a speed change operation in this embodiment.

[Explanation of symbols]

1 Engine 2 Automatic transmission 3 Torque converter 4 Gear transmission device 4a Final drive gear 5 Drive wheel 6 Differential device 7 Control unit 7a Input circuit 7b Output circuit 8 Vehicle speed sensor 9 Throttle opening sensor 10 Various signal sensors 11 Hydraulic control circuit 12 Input shaft 13 Output shaft 14 Counter axis 15 1st speed clutch 16 2nd speed clutch 16a Supply/discharge port 17 3rd speed clutch 17a Supply/discharge port 18 4-speed clutch 18a Supply/discharge port 19 One-way clutch 20 Manual valve 20a 1st port 21 First oil path 22 Spool 23 3-4 shift valve 23a to 23e 1st to 5th ports 24 Second oil passage 25 Spool 26 Spring 27 First oil drain path 27a Branch road 27b Sub-branch road 28 Fixed orifice 29　Drain oil control valve 29a-29d 1st-4th input port 30 Spring 31 Spool 31a-31c 1st-3rd land 32 Third oil passage 32a Branch road 33 Fourth oil passage 33a Branch road 34 Oil drain port 35 Fifth oilway 36 Fixed orifice 37 Second oil drain path 38 2-3 shift valve 39 Oil supply path

Claims (1)

[Claims] 1. A hydraulic control device for an automatic transmission for a vehicle that switches between a plurality of gears by supplying pressure to one of both hydraulic engagement elements for high and low speed gears and discharging pressure from the other, An oil drain control valve that can selectively open and close an oil drain passage of a hydraulic engagement element for a high-speed stage and has a valve body resiliently biased in a closing direction; and first and second pressure-receiving surfaces provided on the valve body to apply hydraulic pressure to move the oil drain path in a direction to open the oil drain passage, and the valve body has first and second pressure receiving surfaces provided on the valve body so as to apply hydraulic pressure to move the oil drain passage in a direction to open the oil drain passage. , characterized in that the exhaust pressure of the hydraulic engagement element for the high speed gear is applied to the first pressure receiving surface, and the supply pressure of the hydraulic engagement element for the low speed gear is applied to the second pressure receiving surface. Hydraulic control device for vehicle automatic transmission.