JPS6037445A - Accumulator of hydraulic control device for automatic speed change gear - Google Patents

Abstract

PURPOSE:To prevent speed change shock by disposing a circular seal material between the step portion of a stepped cylinder and the step portion of a stepped piston. CONSTITUTION:A circular seal material 34 is disposed between the step portion of a stepped cylinder 14 and the step portion of a stepped piston 17, whereby when the piston and cylinder are brought into contact with each other, pressurized oil from an oil path 17 is prevented from leaking out between a small- diameter portion 31 of the stepped cylinder 14 and a small-diameter portion 32 of the stepped piston 17 not to load excessive force upon the stepped piston 17. Accordingly, the piston of the hydraulic servo cylinder is moved at a fixed speed to prevent a speed change shock.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an accumulator that controls the operating speed of a piston of a hydraulic servo cylinder incorporated in a hydraulic control device for an automatic transmission so as to alleviate shock during gear shifting.

Generally used automatic transmissions for vehicles have a torque transmission device such as a torque converter interposed between the output shaft of the engine and the transmission, and selectively operate multiple frictional engagement elements to which pressure oil is supplied and discharged. to achieve different desired gears. A gear range control valve (manual valve) for hydraulic pressure distribution is used as a means to control the supply pressure of pressure oil to each frictional engagement element.
is connected to a control lever or control button that is operated by the driver's will, and the driving state can be freely selected from normal, parking, reverse, neutral, forward automatic transmission, two forward automatic transmission, and fixed set. It is now possible to do so.

As shown in FIG. 1, which shows the concept of an example of such a hydraulic control device for an automatic transmission, this hydraulic control device is for a three-speed forward transmission. When the gear is shifted to the shift position, the accumulator 12, which is the subject of the present invention, is supplied with a hydraulic power source (oil pump) 1.
3 is supplied through an oil passage 15 opening to the stepped portion of the stepped cylinder 14, and further operates the forward clutch 16 to the engaged state.

Here, when the vehicle speed is zero, the stepped piston 17, which is slidably fitted into the stepped cylinder 14 due to the pressure of the pressure oil from the oil passage 15, resists the spring force of the compression spring 18. It is located at the intermediate and descending ends, and pressurized oil is further supplied to the series and reverse brakes 19 to achieve the first gear. At this time,
Pressure oil is not supplied to the hydraulic servo cylinder 20 of the second-speed brake and the reverse and third-speed clutches 21 (not shown), and these are in a released state.

As the vehicle speed increases, the governor 22 operates the 1st-2nd speed shift valve 23, drains pressure oil from the series and reverse brakes 19, releases the brakes by 1, and switches the hydraulic servo. Does not communicate with the maintenance side of the cylinder 20/N control oil passage 24
Internal pressure oil is supplied, and the piston 25 of the hydraulic servo cylinder 20 is displaced to the left in the figure against the spring force of the compression spring 26, shifting the dual player to the holding state and achieving the dual gear stage. be done. At this time, since the control oil passage 24 also communicates with the large diameter portion 27 of the stepped cylinder 14, the stepped piston 17 moves toward - and hi in the figure due to the pressure receiving area difference and the spring force of the compression spring 18. Pushed up, stepped cylinder 14
The state shifts to a state in which the step portion of the stepped piston 17 is in contact with the 0 step portion. For this reason, the moving speed of the piston 25 of the hydraulic servo cylinder 20 is reduced, and the locking is performed slowly, so that the shock during gear shifting is alleviated.

When the vehicle speed further increases, the 2nd-3rd gear shift valve 28 operates and pressure oil is supplied to the reverse and 3rd gear Clara: f21, which becomes engaged, and this pressure oil also releases the 2nd gear brake. Since it is also supplied to the hydraulic servo cylinder 20 via the oil passage 29, the piston 25 is pushed back to the right side in the figure due to the pressure receiving area difference of the piston 25 and the spring force of the compression spring 26, and the dual brake is released. . As a result, the third gear is achieved, but the accumulator 120-stage piston 17 is held at the rising end.

Here, when there is a shift to dual gear due to kickdown or a decrease in vehicle speed, the pressure oil in the release oil passage 29 is depressurized and drained from the hydraulic servo cylinder 20, but the orifice 3
0, the piston 25 moves slowly to the left in the figure, and the dual brakes are not engaged suddenly to prevent shock during gear shifting. 24 and the large diameter 5 part 27 of the stepped cylinder 14 is further ensured by the depressurizing effect of the pressurized oil.

However, in the conventional accumulator 12, 1. =,
Pressure oil from the oil passage 15 leaks from between the stepped portion of the stepped cylinder 14 and the stepped portion of the stepped piston 170 into the gap between the small diameter portion 31 of the stepped cylinder 14 and the small diameter portion 32 of the stepped piston 17. The pressure oil acts as a force that pushes the stepped piston 17 downward in the figure. For this reason, when the gear is changed from third gear to second gear, the stepped cylinder 140 large diameter portion 2
7 may be in a reduced pressure state, the stepped cylinder 17 is momentarily displaced downward, and the pressure inside the control oil passage 24 is not reduced as specified, causing the movement of the piston 25 of the hydraulic servo cylinder 20. The speed will go crazy. As a result, the engagement timing of the dual brakes changed slightly, causing a shift shock.

One way to solve this problem is to install an oil drain passage 33 in the small diameter portion 31 of the single-butted cylinder 14, as shown by the two-dot chain line in Fig. 1.
It is to form. This allows stepped cylinder 1
4 and the small diameter portion 32 of the stepped piston 17 is discharged from the oil drain passage 33.
No extra downward force is applied to the stepped piston 17, and a shock when shifting from third gear to second gear can be prevented.

However, when changing gears from series to double series, part of the pressure oil from the oil passage 15 flows out from the oil drain passage 33, and the rising speed of the stepped piston 17 is accelerated, causing the hydraulic servo cylinder 20
The speed of the piston 25 does not decrease much, resulting in the engagement timing of the dual brakes being out of order and causing a shock.

In view of the problems with the accumulator incorporated in the conventional hydraulic control device for an automatic transmission, the present invention provides an accumulator that allows the piston of a hydraulic servo cylinder to operate as set, thereby preventing shock during gear shifting. What is the purpose?

The structure of the hydraulic control device for an automatic transmission according to the present invention that achieves the above objective is a hydraulic control device that is incorporated into a hydraulic control device for operating a frictional engagement element of an automatic transmission for a vehicle. In an accumulator that controls the operating speed of the pinoton of a hydraulic servo cylinder, a recessed piston is formed with a small diameter part and a large diameter part, and the stepped piston corresponds to /r-small diameter part and large diameter part. and a stepped cylinder in which the stepped piston is slidably fitted, and an oil passage communicating with a hydraulic pressure supply source of the hydraulic control device is opened in the stepped portion of the stepped cylinder. At the same time, the large diameter portion of the stepped cylinder is connected to a shift valve of the hydraulic control device that controls the operation of the piston of the hydraulic servo cylinder, and a side of the hydraulic servo cylinder that engages the friction engagement element, respectively. The control oil passage is opened and is integrally attached to the stepped portion of the stepped cylinder or the stepped piston, and the stepped portion of the stepped cylinder and the stepped piston come into contact. It is characterized by comprising an annular sealing material that prevents pressure oil from the Tsumugi oil passage from leaking into the gap between the small diameter portion of the stepped cylinder and the small f-shaped portion of the stepped to piston in the state. That is.

That is, as shown in FIG. 2, which shows the cross-sectional structure of the accumulator part of an embodiment in which the present invention is applied to the hydraulic control device shown in FIG. Pressure oil is supplied from the control oil passage 24 to the large diameter portion 27 of the stepped cylinder 14, and the stepped cylinder 14 is fitted integrally with When the stepped portion of the stepped piston 17 is in contact with the stepped portion, pressure oil from the oil passage 15 is prevented from leaking into the gap between the small diameter portion 31 of the stepped cylinder 14 and the small diameter portion 32 of the stepped piston 17. This is what I did.

Therefore, since no extra downward force is applied to the stepped piston 17, the piston 25 of the hydraulic servo cylinder 20 moves at a predetermined speed when shifting from third gear to two gears, and the two gear brakes move at a predetermined speed. engages in a timely manner, eliminating the occurrence of shock.

Note that the sealing material 341 may be integrally fitted into the recessed portion of the stepped cylinder 140, and the cross-sectional shape of the sealing material 34 is not limited to this embodiment, and can be arbitrarily set. In this embodiment, an accumulator for a hydraulic servo cylinder of a two-speed brake has been described, but it can be used for other frictional engagement elements as well.

As described above, the accumulator t of the automatic transmission hydraulic control device of the present invention is provided with an annular sealing material that seals between the stepped portion of the stepped cylinder and the stepped portion of the stepped piston. Pressure oil from the oil passage does not leak between the small diameter part of the stepped cylinder and the small diameter part of the stepped piston when they are in contact, and therefore no extra force is applied to the stepped piston. The piston moves at a predetermined speed, and it will be possible to prevent gear shift shock.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing the concept of a conventional hydraulic control device for a three-speed forward automatic transmission, and FIG. 2 is a sectional view showing the structure of an embodiment of an accumulator according to the present invention. 12 is an accumulator, 13 is a hydraulic pressure supply source, 14 is a stepped cylinder, 15 is an oil passage, 17 is a stepped piston, 20 is a hydraulic servo cylinder, 24 is a control oil passage, 25 is a piston, and 27 is a stepped cylinder. 29 is a release oil passage; 31 is a small diameter portion of the stepped cylinder; 32 is a small diameter portion of the stepped piston; 34 is a sealing material. Patent applicant Patent attorney representing Mitsubishi Motors Corporation
Shibu Mitsuishi (1 other person) 11- Riff C-

Claims (1)

[Claims] In an accumulator that controls the operating speed of a piston of a hydraulic servo cylinder incorporated in a hydraulic control device for operating a frictional engagement element of an automatic transmission for a vehicle,
A stepped piston in which a small diameter portion and a large diameter portion are formed, and a stepped cylinder in which a small diameter portion and a large diameter portion corresponding to the stepped piston are formed and the stepped piston is slidably fitted. An oil passage communicating with the hydraulic pressure supply source of the hydraulic control device is opened in the stepped portion of the stepped cylinder, and a large diameter portion of the stepped cylinder is configured to operate the piston of the hydraulic servo cylinder. A control oil passage that communicates with the shift valve of the hydraulic control device to be controlled and the side of the hydraulic servo cylinder that engages the frictional engagement element is opened, and is connected to a stepped portion of the stepped cylinder or the stepped piston. When the stepped portion of the stepped cylinder is integrally attached to the stepped portion and the stepped portion of the stepped cylinder is in contact with the stepped portion of the stepped piston, pressure oil from the oil passage is applied to the small diameter portion of the stepped cylinder and the stepped piston. An accumulator for a hydraulic control device for an automatic transmission, comprising an annular sealing material that prevents leakage into a gap between the accumulator and the small diameter portion of the accumulator.