JPH05126175A - Brake servo device for automatic transmission - Google Patents

Abstract

PURPOSE:To provide a brake servo device capable of being disposed rationally inside a center support. CONSTITUTION:A spring containing hole 24 extending axially avoiding a position where a diametric oil passage 23 is formed is formed in a center support 2. A return spring 6 is disposed there, and the diametric oil passage 23 is inclined toward a friction engagement element 4 as it approaches closer to an inner circumferential surface of the center support 2, and both a cylinder chamber 3 and a return spring 6 are disposed at similar axial positions in the center support 2 where the diametric oil passage 23 is formed while avoiding interference the cylinder chamber 3 and the return spring 6 with the diametric oil passage 23 in the center support 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for an automatic transmission, and more particularly to a servo device as its operating means.

[0002]

2. Description of the Related Art Automatic transmissions for vehicles are downsized from the standpoint of mountability, and are lightweight and multi-staged in terms of fuel economy, running performance, and riding comfort, and each element in the transmission is as small as possible. The weight is reduced, and they are arranged close to each other or overlap each other in the axial direction and the radial direction. Japanese Patent Application Laid-Open No. 61-41050 discloses a brake device that is an element of such an automatic transmission as an arrangement for shortening the axial dimension of a servo device which is an operating means for engaging and disengaging the friction engagement element. As can be seen, there is a configuration in which a return spring is arranged radially inside the annular piston.

As a structure for further reducing the axial dimension of the brake device having such a structure, the position of the device is arranged on the input side having a large transmission case diameter (hereinafter, the input side will be referred to as the front for convenience of explanation, Move the output side to the rear),
It is envisioned that the friction material diameter of the friction engagement element is increased by the increase in the radial dimension to reduce the number of friction members and the axial dimension. On the other hand, in order to downsize the member size itself and shorten the axial size, it is recalled that the return spring is a disc spring, as disclosed in JP-A-2-26347.

[0004]

However, the latter method has a problem that it is difficult to maintain a predetermined spring characteristic because the disc spring has a lower load accuracy than the coil spring. On the other hand, in the former method, although it is possible to shorten the axial dimension by the amount that the radial dimension can be increased, there is a power transmission drum in front of the braking device that intensively includes the transmission elements in front of it. In the case of such an arrangement, it is more rational to form the cylinder chamber in the center support in order to reduce the axial dimension more effectively. Since a radial oil passage for supplying
If the above configuration is simply adopted, it is not possible to achieve a sufficient size reduction effect due to the interference between the oil passage extending in the radial direction and the cylinder chamber that orbits the entire circumference.

In view of such a situation, the present invention can further reduce the axial dimension while maintaining the structure in which the return spring is disposed on the radial inner side of the conventional annular piston, and further reduce the axial dimension. An object of the present invention is to provide a brake servo device that can be reasonably arranged.

[0006]

In order to solve the above problems, the present invention is directed to a center support having a radial oil passage extending from the outer peripheral surface to the inner peripheral surface, and an annular ring on the outer diameter side of the center support. A cylinder chamber defined by the above, an annular piston axially slidably disposed in the cylinder chamber for engaging and disengaging the friction engagement element, and a disengagement position of the annular piston with the friction engagement element. And a return spring that pushes back into the center support, a spring accommodating hole extending in the axial direction is formed in the center support so as to avoid the formation position of the radial oil passage, and the return spring is disposed in the spring accommodating hole. The directional oil passage is formed so as to be inclined toward the friction engagement element toward the inner peripheral surface side of the center support.

[0007]

In the brake servo device according to the present invention having such a structure, the radial oil passage in the center support is formed so as to be inclined toward the friction engagement element toward the inner peripheral surface side. , So that the axial position of the cylinder chamber and the axial position of the return spring are almost the same,
Further, since the return spring accommodating hole is formed avoiding the position where the radial oil passage is formed, both the cylinder chamber and the return spring are arranged at the same axial position in the center support where the radial oil passage is formed. Nevertheless, it is possible to avoid interference with the radial oil passage in the center support.

Therefore, according to the present invention, the cylinder chamber and the return spring can be arranged in the center support so as to completely overlap each other in the radial direction, and the brake servo device utilizing the axial thickness of the center support. The axial dimension of can be significantly reduced. further,
As a side effect, the cylinder chamber and spring accommodating hole can be replaced with a lightening hole that should originally be formed in the center support to reduce the weight, so the installation space for the brake servo device can be used to reduce the weight. The effect of reducing the weight of the automatic transmission can also be obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a partial sectional view of an embodiment of an automatic transmission to which the present invention is applied, and FIG. 2 is a front view of a center support portion thereof. The automatic transmission of this embodiment is a 5-speed automatic transmission in which a 4-speed main transmission using a not-illustrated simple-coupling 3-planetary gear train and a front-mounted overdrive planetary gear P shown on the left side of FIG. 1 are combined. In this example, the brake servo device of the present invention is applied to the brake B that is engaged at the third speed or higher.

The transmission case 1 is divided into an accommodating portion for the main transmission and an accommodating portion for the overdrive planetary gear P by a center support 2 having a radial oil passage 23 extending from the outer peripheral surface 21 to the inner peripheral surface 22. Has been done. An annularly defined cylinder chamber 3 is formed on the outer diameter side of the center support 2, and an annular piston 5 is axially slidably disposed in the cylinder chamber 3 so as to disengage and disengage the frictional engagement element 4. Has been done. A return spring 6 is provided on the inner diameter side of the center support 2 to release the annular piston 5 from the engagement with the friction engagement element 4 and push it back to the non-engagement position. Further, a spring accommodating hole 24 extending in the axial direction is formed in the center support 2 while avoiding the formation position of the radial oil passage 23, and a return spring 6 is arranged in the spring accommodating hole 24. The radial oil passage 23 is provided in the center support 2
Is inclined toward the frictional engagement element 4 toward the inner peripheral surface 22 side.

More specifically, the center support 2 has an outer peripheral flange portion 2a extending forward at the outer peripheral portion thereof, an inner peripheral flange portion 2b extending rearward at the inner peripheral portion thereof, and the both are connected to each other and the inner peripheral side is inclined rearward. It is provided with a radial flange portion 2c. The outer peripheral flange portion 2a is fitted on a step portion of a spline 11 formed on the inner peripheral surface of the peripheral wall of the case 1 to prevent the friction material of the friction engagement element 4 from rotating, and the snap ring 12 is fixed to the input side to fix the case 1 The inner peripheral surface 22 of the inner peripheral flange portion 2b is supported by the power transmission shaft S via a bearing.
Rotatably supported, the front end surface supports the ring gear flange portion F of the overdrive planetary gear P via the thrust bearing, and the rear end surface supports the radial direction flange portion of the power transmission shaft S via the thrust bearing. .

A cylinder chamber 3 formed on the outer diameter side of the center support 2 is open to the friction engagement element 4 side, and an O-ring is fitted to the inner and outer circumferences thereof to form an annular piston 5 which is oil-tightly inserted. In order to avoid interference with the front end of the brake hub H that supports the friction material of the brake B, the intermediate diameter portion is formed with an annular notch and has a U-shaped cross section. Project slightly rearward from the side and return spring 6
And an engaging portion of the connecting member 61.

The return spring 6 has its front end side abutted and supported by a seat portion of a connecting member 61 having the same structure as the conventional one, and its rear end side supported by a radial flange portion 2c of the center support 2 by a snap ring. The spring 62 is brought into contact with the retainer 62 and is housed in the spring housing hole 24 in a compressed state, and a forward load, that is, a piston returning force is applied to the connecting member 61 by using the retainer 62 as a supporting member. In this embodiment, the spring accommodating hole 24 is formed in a left-right symmetrical fan shape with the oil passage 23 in between, and penetrates the radial flange portion 2c of the center support 2, as shown in FIG. A return spring 6 composed of a plurality of coil springs is arranged in parallel.

The oil passage 23 is formed so as to be inclined rearward from the back of the cylinder chamber 3 toward the inner diameter side, and the position on the inner diameter side is substantially the same as the axial direction position of the cylinder chamber 3. In this embodiment, the radial flange portion 2c of the center support 2 is also inclined so as to follow the inclination of the oil passage, but this is the ring gear flange of the overdrive planetary gear P arranged in front of the center support 2. The center support 2 and the center support 2 are arranged in the vicinity of the center support 2 to reduce the axial dimension. The brake B is arranged in series with the one-way clutch OC on the radially inner side, and the one-way clutch OC includes an outer race integrated with the brake hub H, and the inner race is fitted to the outer circumference of the inner circumferential flange portion 2b of the center support 2. The inner race is connected to the power transmission drum in a freely rotatable manner via a bearing.

In this device, the brake B is arranged in series with the one-way clutch OC so as to engage or disengage the power transmission drum from the case 1 via the one-way clutch OC. That is, when the annular piston 5 is pushed out against the load of the return spring 6 by the hydraulic pressure supplied into the cylinder chamber 3 via the oil passage 23, the rear end surface of the annular piston 5 is a snap ring on the rear end side. The front end surface of the friction material that has been stopped in the axial direction is pressed, and the friction materials are engaged with each other to be in the brake engagement state. On the other hand, when the oil supplied into the cylinder chamber 3 is drained, the annular piston 5 is returned into the cylinder chamber 3 by the action of the spring load due to the removal of the engagement pressure.

According to the above embodiment, the spring accommodating hole 2
Since 4 is a through hole, the hole can be used as a ventilation hole to perform a function of enhancing the ventilation effect between both sides of the center support, and the axial length can be secured by the through hole, and it is accommodated inside thereof. Since it is also possible to set the free length of the return spring to be long, it is possible to obtain the effect of increasing the degree of freedom in setting the spring.

The present invention has been described above in detail based on an embodiment, that is, an example of a 5-speed automatic transmission in which a simple-coupling 3-planetary gear train and a front-mounted overdrive planetary gear are combined. Is not limited to this, and the arrangement position and shape thereof are not limited to those in the above-described embodiment, and various configurations can be adopted within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an automatic transmission to which a brake servo device of the present invention is applied.

FIG. 2 is a front view of a center support part shown with some members removed.

[Explanation of symbols]

 2 Center support 3 Cylinder chamber 4 Friction engaging element 5 Annular piston 6 Return spring 21 Outer peripheral surface 22 Inner peripheral surface 23 Radial oil passage 24 Spring accommodation hole

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Akihiro Kuroyanagi, 10 Takane, Fujii-cho, Anjo City, Aichi Prefecture, Aisin A / D Aburyu Co., Ltd. (72) Kazuma Tsukamoto, Takane, Fujii-cho, Anjo City, Aichi Prefecture (72) Inventor Yasuo Hojo, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Hidehiro Ohba 1 Toyota Town, Aichi Prefecture, Toyota Motor Corporation

Claims (1)

[Claims] 1. A center support having a radial oil passage extending from an outer peripheral surface to an inner peripheral surface, a cylinder chamber defined annularly on the outer diameter side of the center support, and axially slidable into the cylinder chamber. The center support includes an annular piston that is movably disposed to engage and disengage the friction engagement element, and a return spring that returns the annular piston to a non-engagement position with the friction engagement element. A spring accommodating hole extending in the axial direction is formed so as to avoid the position where the passage is formed, the return spring is disposed in the spring accommodating hole, and the radial oil passage extends toward the inner peripheral surface of the center support. A brake servo device for an automatic transmission, wherein the brake servo device is formed so as to be inclined toward the friction engagement element.