JPH0112983B2 - - Google Patents

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 control multiple frictional engagement elements to which pressure oil is supplied and discharged. The gears are engaged with each other to achieve different desired gears. A gear range control valve (manual valve) for oil pressure distribution as a means to control the supply and discharge of pressure oil to each friction engagement.
are connected to control levers and buttons that are operated by the driver's will, and are normally used for parking, reverse, neutral, forward automatic transmission, forward two-speed automatic transmission,
It is possible to select any operating state such as fixed first speed.

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 shift position D is operated, the accumulator 12, which is the object of the present invention,
Pressure oil from a hydraulic supply source (oil pump) 13 is supplied to the stepped cylinder 14 through a first oil passage 15 that opens on the stepped side of the large diameter portion 27, and further engages the forward clutch 16. operate in the correct 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 first oil passage 15, resists the spring force of the compression spring 18. In the figure, it is located at the descending end,
Further, pressure oil is supplied to the first gear and reverse brake 19 to achieve the first gear. At this time, the engaging side hydraulic chamber 20a of the hydraulic servo cylinder 20 of the second speed brake (not shown) and the clutch 21 for reverse and third speed are connected.
Pressure oil is not supplied to and, and these are in a released state.

As the vehicle speed increases, the governor 22 shifts to first gear.
The second-speed shift valve 23 is activated, pressure oil is discharged from the first-speed and reverse brake 19, and the engagement is released, and the second control is communicated with the engagement-side hydraulic chamber 20a of the hydraulic servo cylinder 20. Pressure oil is supplied to the oil passage 24, and the piston 2 of the hydraulic servo cylinder 20
5 is displaced to the left in the drawing against the spring force of the compression spring 26, the second speed brake is shifted to the engaged state, and the second speed shift stage is achieved. At this time, the second oil path 2
4 also communicates with the large diameter portion 27 on the opposite side of the stepped portion of the stepped cylinder 14, so that the stepped piston 17
is pushed upward in the figure due to the pressure receiving area difference and the spring force of the compression spring 18, and the stepped cylinder 1
The state shifts to a state in which the stepped portion of the stepped piston 17 is in contact with the stepped portion of the stepped piston 17 . For this reason, the moving speed of the piston 25 of the hydraulic servo cylinder 20 is reduced, and the engagement is performed more slowly, thereby relieving the shock during gear shifting.

When the vehicle speed further increases, the 2nd-3rd gear shift valve 2
8 is activated, pressure oil is supplied to the reverse and third speed clutch 21 and it becomes engaged, and furthermore, this pressure oil is supplied to the release side of the hydraulic servo cylinder 20 via the second speed brake release oil passage 29. Since the oil is also supplied to the hydraulic chamber 20b, the piston 25 moves as shown in the figure due to the pressure receiving area difference of the piston 25 and the spring force of the compression spring 26.
It is pushed back to the right and the second gear brake is released.
As a result, the third gear is achieved, but the stepped piston 17 of the accumulator 12 is held at the rising end.

Here, when there is a shift to second gear due to a 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 30 causes the piston 25 to It moves slowly to the middle and left side, and the second gear brake is not engaged suddenly to prevent shock when changing gears. This function is performed by the second oil passage 2.
4 and the large-diameter portion 27 of the stepped cylinder 14 to reduce the pressure therein.

However, in the conventional accumulator 12, the small diameter part 31 of the stepped cylinder 14 and the stepped piston 1 are connected from the large diameter part 27 side of the stepped cylinder 14.
Pressure oil from the first oil passage 15 leaks into the gap between the first oil passage 15 and the small diameter portion 32 of the piston 7, and this pressure oil acts as a force that pushes the stepped piston 17 downward in the figure.
For this reason, when the gear is shifted from third gear to second gear, the pressure oil in the large diameter portion 27 of the stepped cylinder 14 may become depressurized, causing the stepped cylinder 17 to be momentarily displaced downward, resulting in The pressure inside the second oil passage 24 will not be reduced as specified, and the moving speed of the piston 25 of the hydraulic servo cylinder 20 will be out of order. As a result, the engagement timing of the second-speed brake changes slightly, resulting in a shift shock.

As one means to solve this problem,
The technique disclosed in Japanese Patent No. 56-39348, particularly in FIG. 3A, is known. In other words, as shown by the two-dot chain line in FIG.
The purpose is to form an oil drain path 33 in the drain. As a result, the pressure oil leaking into the gap between the small diameter part 31 of the stepped cylinder 14 and the small diameter part 32 of the stepped piston 17 is discharged from the oil drain passage 33, so that an excessive downward force is applied to the stepped piston 17. This prevents shock when shifting from third to second gear.

However, when shifting from first gear to second gear, part of the pressure oil from the first oil passage 15 flows out from the oil drain passage 33, and the rising speed of the stepped piston 17 is prematurely increased. The speed of the piston 25 of No. 20 does not decrease much, resulting in the engagement timing of the second speed brake being out of order and causing a shock.

In view of the problems of 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. With the goal.

The structure of the accumulator of the automatic transmission hydraulic control device of the present invention that achieves this object includes an engagement side hydraulic chamber to which pressure oil for engaging the frictional engagement elements of the vehicle automatic transmission is supplied. an accumulator that is incorporated in a hydraulic control device having a hydraulic servo cylinder and a release-side hydraulic chamber to which pressure oil for releasing the frictional engagement element is supplied, and that controls the operating speed of a piston of the hydraulic servo cylinder; A stepped piston having a small diameter portion and a large diameter portion, and a stepped piston having a small diameter portion and a large diameter portion corresponding to the stepped piston and into which the stepped piston is slidably fitted. A first oil passage communicating with the hydraulic pressure supply source of the hydraulic control device is opened on the stepped side of the large diameter portion of the stepped cylinder, and a first oil passage communicating with the stepped portion of the stepped cylinder is opened. In the accumulator, a second oil passage communicating with the engagement side hydraulic chamber is opened in the large diameter portion on the opposite side,
The pressure from the oil passage is integrally attached to the step of the stepped cylinder or the step of the stepped piston, and when the step of the stepped cylinder and the step of the stepped piston are in contact with each other, It is characterized by comprising an annular sealing material that prevents oil from leaking from the large diameter side to the small diameter side of the stepped cylinder.

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. are integrally fitted, pressure oil is supplied from the second oil passage 24 to the large diameter portion 27 of the stepped cylinder 14, and the stepped piston 1
The stepped piston 17 is attached to the stepped portion of the stepped cylinder 14 due to the pressure receiving area difference of 7 and the spring force of the compression spring 18.
When the stepped portions of the stepped cylinder 14 are in contact, the stepped cylinder 14
The small diameter portion 31 of the stepped piston 17 and the small diameter portion 32 of the stepped piston 17
The pressure oil from the first oil passage 15 is prevented from leaking into the gap between the first oil passage 15 and the first oil passage 15.

Therefore, since no extra downward force is applied to the stepped piston 17, the piston 25 of the hydraulic servo cylinder 20 is
moves at a predetermined speed, and the second-speed brake engages in a timely manner, eliminating the occurrence of shock.

Note that the sealing material 34 may be integrally fitted into the stepped portion of the stepped cylinder 14, and the cross-sectional shape of the sealing material 34 is not limited to this embodiment, and can be arbitrarily set.

As described above, according to the accumulator of the automatic transmission hydraulic control device of the present invention, the annular sealing material is provided to seal between the stepped portion of the stepped cylinder and the stepped portion of the stepped piston, so that they come into contact. Hydraulic servo The piston of the cylinder moves at a predetermined speed, and a shift shock can be prevented.

[Brief explanation of drawings]

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 supply source, 1
4 is a stepped cylinder, 15 is a first oil passage, 17 is a stepped piston, 20 is a hydraulic servo cylinder, 2
0a is the engagement side hydraulic chamber, 20b is the release side hydraulic chamber, 2
4 is the second oil passage, 25 is the piston, 27 is the large diameter part of the stepped cylinder, 29 is the release oil passage, 31 is the small diameter part of the stepped cylinder, 32 is the small diameter part of the stepped piston, and 34 is the seal. It is a material.

Claims (1)

[Claims] 1 An engagement-side hydraulic chamber to which pressure oil for engaging the frictional engagement element of a vehicle automatic transmission is supplied, and a disengagement-side hydraulic chamber to which pressure oil to release the frictional engagement element is supplied. The accumulator is incorporated in a hydraulic control device having a hydraulic servo cylinder formed with a cylinder to control the operating speed of a piston of the hydraulic servo cylinder, the stepped piston having a small diameter part and a large diameter part, and a stepped piston having a small diameter part and a large diameter part; a stepped cylinder in which a small diameter portion and a large diameter portion corresponding to the stepped piston are formed, and into which the stepped piston is slidably fitted; A first oil passage communicating with the hydraulic pressure supply source of the hydraulic control device is opened, and a second oil passage communicating with the engaging side hydraulic chamber is provided in a large diameter portion of the stepped cylinder opposite to the stepped portion. In an accumulator with an open passage, the step is integrally attached to the step of the stepped cylinder or the step of the stepped piston, and the step of the stepped cylinder and the step of the stepped piston are in contact with each other. A hydraulic control device for an automatic transmission, comprising an annular sealing material that prevents pressure oil from the oil passage from leaking from the large-diameter side to the small-diameter side of the stepped cylinder. Accumulator.