JPH0736206Y2 - Structure of hydraulic servo mechanism of automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a structure of a hydraulic servo mechanism for engaging and disengaging friction engagement means such as a clutch and a brake in an automatic transmission.

2. Description of the Related Art An automatic transmission for a vehicle includes a plurality of planetary gear mechanisms, and the sun gear and ring gear in each planetary gear mechanism and each element of a carrier are connected to each other by a clutch, or to an input shaft or an output shaft, and by a brake. It is well known that the clutch is fixed, a predetermined gear ratio is set according to the connected / fixed state, and the friction engagement means such as a clutch and a brake is operated by a servo mechanism that operates hydraulically. This type of hydraulic servo mechanism is configured as a single-acting hydraulic cylinder in order to simplify the configuration. More specifically, the piston is housed inside the cylinder, which is an annular cylindrical portion, so that it can be moved back and forth. In addition, the piston is configured to be moved backward by a return spring, an example of which is disclosed in Japanese Utility Model Laid-Open No. 62-89555.

Since the return spring for moving the piston backward is assembled with the preload applied, it is necessary to hold the return spring so that it does not move in the circumferential direction relative to the piston. It is configured as shown in. That is, FIG. 4 is a cross-sectional view showing an example of a hydraulic servo mechanism for engaging and disengaging a brake, in which a piston P is housed in a cylinder C having an annular shape so as to be movable back and forth, and its outer circumference. A seal material S is disposed on the inner peripheral portion and the inner peripheral portion, an inner peripheral wall portion I extending in the axial direction is provided on the cylinder C, and a retainer R facing the piston P is snap ringed at the tip portion of the inner peripheral wall portion I. Mounted by Sr and retainer R
A return spring Rs is arranged between the piston and the piston P.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described conventional structure, the axial length of the inner peripheral wall portion I that constitutes a part of the cylinder C is increased, so that the axial length of the automatic transmission is shortened. There was a problem that became an obstacle. That is, since the piston P is in sliding contact with the outer peripheral surface of the inner peripheral wall portion I, the inner peripheral wall portion I needs to have at least the length of the inner peripheral portion of the piston P and the stroke, and not only that, but also the snap ring Sr. For maintaining strength to withstand the elastic force of the peripheral groove and the return spring Rs, and a taper portion for preventing the seal material S on the inner peripheral side from being damaged when the piston P is inserted into the cylinder C. The dimension for T is required, and as a result, the length of the inner peripheral wall portion I of the cylinder C becomes long, which is a factor of increasing the axial length of the automatic transmission.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a structure of a hydraulic servo mechanism capable of reducing the axial dimension of an automatic transmission.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention moves a piston by supplying hydraulic pressure to the inside of a cylinder to engage a friction engagement means, and a piston is provided with a return spring. In an automatic transmission that presses in a direction opposite to the moving direction by hydraulic pressure to release a friction engagement means, an outer race of a one-way clutch is opposed to the piston and is fixed relatively in a circumferential direction. In addition to being arranged, one end of the return spring is brought into contact with and supported by the outer race.

Therefore, according to the structure of the hydraulic servo mechanism of the present invention,
Since the outer race also serves as the retainer for the return spring, the retainer that was required in the past can be omitted, and the part that is unavoidably provided on the cylinder due to the use of the retainer can be deleted and the axial length can be shortened. .

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of an automatic transmission having a hydraulic servomechanism 1 according to the present invention, which hydraulic servomechanism 1 presses a friction plate 3 of a brake 2 in an axial direction to form a brake 2
Are configured to engage. That is, the hydraulic servo mechanism 1 includes a piston 4, a cylinder member 5 that houses the piston 4 toward the friction plate 3 so as to be movable back and forth, and a return spring 6 that presses the piston 4 in a direction away from the friction plate 3. It is configured as the main body,
As shown in the exploded view in FIG. 2, the cylinder member 5 is an annular cylindrical member having an annular recess that serves as a hydraulic chamber 7, and its outer peripheral surface 8 is located at a predetermined position of the case 9. It is a smooth surface that fits in close contact with the inner peripheral surface 10, which is a smooth arc surface formed. A plurality of engaging teeth 11 projecting in the axial direction are formed at the tip of the outer peripheral portion of the cylinder member 5 (the right end in FIGS. 1 and 2) at regular intervals in the circumferential direction. .

On the other hand, the piston 4 is an annular member that is in sliding contact with the inner surface of the hydraulic chamber 7 along the axial direction, that is, the inner surface of the outer peripheral wall portion of the cylinder member 5 and the outer surface of the central side wall portion. O as a sealant on both sides
The rings 12, 13 are fitted together. Further, like the engaging teeth 11, a plurality of pressing projections 14 projecting in the axial direction at predetermined intervals in the circumferential direction are formed on the outer peripheral portion of the piston 4, and the pressing projections 14 are formed. A ring groove 16 for fitting the snap ring 15 is formed on the inner peripheral portion of the tip of 14.

The cylinder member 5 is fitted inside the case 9 so that the outer peripheral surface 8 thereof is substantially in close contact with the inner peripheral surface 10 of the case 9, and in this state, the rear end side in the axial direction (see FIGS. 1 and 2). The position on the left end side in the figure) is determined by a snap ring 17 fitted to the inner peripheral portion of the case 9. The piston 4 is housed in an annular recess of the cylinder member 5 so as to be movable back and forth, and a hydraulic chamber 7 is formed on the rear end side. Further, the return spring 6 is arranged on the front side of the piston 4 so as to retract the piston 4 toward the cylinder member 5, and the front end portion of the return spring 6 is supported by the outer race 19 of the one-way clutch 18.

As shown in FIG. 2 and FIG. 3, the outer race 19 has a plurality of arm portions whose tip ends reach the inner peripheral portion of the case 9.
The outer race 19 is formed by radially projecting 20 around the outer circumference of an annular portion.
Is attached to the inner peripheral portion of the case 9 in a state of being engaged with the spline groove 21 formed on the inner surface of the case 9 and is fixed in the axial direction by a snap ring 22 fitted to the inner peripheral portion of the case 9. .

The engaging teeth 11 of the cylinder member 5 extend between the arm portions 20 of the outer race 19 and extend in the circumferential direction.
The portion of the engaging teeth 11 corresponding to the bottom of each engaging tooth 11 is in contact with the side portion of the arm portion 20. As a result, the cylinder member 5 is circumferentially and axially separated by the outer race 19. Positioned and fixed relative to the direction. In addition, the pressing projections 14 of the piston 4 extend between the arms 20 to the opposite side of the cylinder member 5 with the arm 20 interposed therebetween. Part ring groove 16
The snap ring 15 is fitted to. Therefore, the piston 4 is pressed to the cylinder member 5 side by the return spring 6, and the pressing force is applied to the snap ring 15.
Therefore, the piston 4 is substantially assembled to the outer race 19 with the return spring 6 sandwiched between the outer race 19 and the return spring 6.

The inner peripheral surface of the outer race 19 and the outer race 19
For example, a sprag 24 and an end bearing 25 are arranged between the outer peripheral surface of the inner race 23 arranged concentrically with, and the sprag 24 and the end bearing 25 are
Outer race with the tip of the inner wall of the cylinder member 5
It is positioned and held in the axial direction by a retainer 26 attached to the end of 19.

Further, one of the friction plates 3 of the brake 2 is engaged with the spline groove 21 with which the tip end of the arm portion 20 is engaged, and another friction plate 3 alternately arranged with respect to the friction plate 3 is engaged. The friction plate 3 is spline-fitted to the outer peripheral portion of the brake drum 27 connected to the inner race 23 of the one-way clutch 18.

Reference numeral 28 in FIG. 1 denotes a planetary gear mechanism in which the teeth on the inner peripheral surface of the inner race 23 are ring gears, and reference numeral 29 denotes a clutch connected to the carrier of the planetary gear mechanism 28.

Therefore, in the hydraulic servomechanism 1 described above, by supplying hydraulic pressure to the hydraulic chamber 7, the piston 4 compresses the return spring 6 and moves forward, and the pressing projection 14 thereof presses the friction plate 3 of the brake 2. The lever 2 is engaged (brought into a braking state). When the pressure is discharged from the hydraulic chamber 7, the piston 4 is pushed by the return spring 6 and retracts, and the brake 2 is released.

According to the hydraulic servo mechanism 1 having the above-described structure, one end of the return spring 6 for moving the piston 4 backward is supported by the outer race 19, so that it is conventionally necessary to hold the return spring 6. Since the retainer and the snap ring for fixing the retainer are omitted, the inner peripheral wall portion of the cylinder member 5 can be shortened accordingly, and the constituent members of the automatic transmission can be brought closer to each other, and the axial length of the automatic transmission can be shortened. Can be realized. Further, since the piston 4 can be assembled in advance to the outer race 19 by the return spring 6 and the snap ring 15, and these can be inserted into the case 9 as a unit to perform the assembly work, the assembly workability is improved. Will be good. Further, the above hydraulic servo mechanism 1
Then, if a slight gap is set between the portion corresponding to the bottom of the engaging tooth 11 formed on the cylinder member 5 and the arm portion 20 of the outer race 19, the cylinder member 5 resists the return spring 6. Therefore, it is possible to move the cylinder member 5 in the axial direction, and therefore, if another friction engagement means is arranged on the back side (left side in FIG. 1) of the cylinder member 5, the cylinder member 5 can be moved to the other friction engagement means. It can also be used as a cushion plate.

In this invention, it suffices for the cylinder member to have a function of accommodating the piston so that the piston can be moved back and forth, and it may be, for example, a center support having a function other than this as well. The configuration is not limited to that shown in the embodiment.

As described above, according to the structure of the hydraulic servo mechanism for the automatic transmission of the present invention, one end of the return spring for moving the piston backward is arranged adjacent to the hydraulic servo mechanism. Since it is supported by the outer race of the one-way clutch, the retainer and the snap ring for fixing the retainer, which were conventionally required, can be omitted, and the part of the cylinder for attaching the retainer or snap ring can be omitted accordingly. Since it is unnecessary, the cylinder can be shortened, and by arranging the constituent members of the automatic transmission closer to each other, the axial length of the automatic transmission can be shortened. Moreover, since the outer race has high rigidity, the durability of the mechanism for holding the return spring is improved. Furthermore, since the retainer used in the past can be omitted, the space in the radial direction, which had to be secured for the retainer, is unnecessary, and as a result, the radial dimension of the automatic transmission is reduced. You can also

[Brief description of drawings]

1 is a schematic partial sectional view of an automatic transmission incorporating a hydraulic servo mechanism to which the present invention is applied, FIG. 2 is a schematic exploded sectional view of the hydraulic servo mechanism, and FIG. 3 is FIG. FIG. 4 is a partially cutaway partial view of the hydraulic servo mechanism shown in FIG. 6 when viewed from the tip side of the piston, and FIG. 4 is a partial sectional view showing an example of a conventional hydraulic servo mechanism. 1 ... hydraulic servo mechanism, 2 ... brake, 4 ... piston, 5 ... cylinder member, 6 ... return spring,
7 ... Oil chamber, 18 ... One-way clutch, 19 ... Outer race.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A hydraulic fluid is supplied to the inside of a cylinder to move a piston to engage a friction engagement means, and a return spring presses the piston in a direction opposite to the hydraulic pressure to cause a friction engagement. In the automatic transmission for releasing the coupling means, the outer race of the one-way clutch is arranged so as to face the piston and is fixed relative to the circumferential direction, and one end of the return spring is attached to the outer race. The structure of the hydraulic servo mechanism of the automatic transmission, which is supported by abutting against the race.