JPH0612868U - Automatic transmission - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent oil leakage from the drain circuit and the inclusion of air, and to keep the back pressure chamber filled with oil when the back pressure is released so that the piston operation response Be able to speed up sex. [Structure] A drain circuit 43 communicated with a back pressure chamber 4b formed between a piston 4 and a centrifugal cancel piston 5.
Is formed on the mission case 3 and the fixing member 30,
The drain discharge port 44 at the drain side tip of the drain circuit 43 is arranged above the uppermost position H of the back pressure chamber 4b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an automatic transmission of an automobile, and more particularly to a drain circuit of a centrifugal cancel piston.

[0002]

[Prior art]

 Conventionally, as an automatic transmission having a centrifugal cancel piston, for example, one described in Japanese Patent Laid-Open No. 2-296073 is known. In this prior art document, a rotary drum is supported by a case or a fixed member fixed to this case, and a pressure receiving chamber for applying a hydraulic pressure in a clutch engaging direction to a piston provided in the rotary drum is A back pressure chamber that is formed between the rotary drum and applies a hydraulic pressure in the clutch releasing direction to the piston is formed between the piston and the centrifugal cancel piston, and a drain circuit that communicates with the back pressure chamber is formed. , Which is formed by a groove formed on the inner diameter side sliding surface of the centrifugal cancel piston.

[0003]

[Problems to be solved by the device]

 However, in the conventional automatic transmission having such a structure, the drain circuit communicating with the back pressure chamber is formed by the groove formed on the inner diameter side sliding surface of the centrifugal cancel piston. Oil leakage from the drain circuit and air mixing easily occur, which causes problems such as not being able to obtain sufficient working pressure to the piston or making the working pressure incorrect.

Further, if the supply of the hydraulic pressure to the back pressure chamber is stopped, all the oil in the back pressure chamber will escape from the drain circuit, so it will take time to re-supply the oil, and the operation response of the piston will become slow. There was a problem of being lost.

The present invention has been made in view of the above problems, and prevents oil leakage from the drain circuit and mixing of air, and when the back pressure is released, the back pressure chamber is filled with oil. It is an object of the present invention to provide an automatic speed changer that can be maintained as it is and can speed up the operation response of the piston.

[0006]

[Means for Solving the Problems]

 Therefore, in the present invention, the drain circuit outlet is opened above the back pressure chamber to solve the above problem.

That is, in the automatic transmission of the present invention, the rotating drum is supported by the case or the fixed member fixed to the case, and the working fluid pressure in the clutch engaging direction is applied to the piston provided in the rotating drum. An automatic transmission in which a pressure receiving chamber is formed between the piston and the rotary drum, and a back pressure chamber for applying a working fluid pressure in the clutch releasing direction to the piston is formed between the piston and the centrifugal cancel piston. In the above, the drain circuit communicating with the back pressure chamber is formed in the case or the fixing member, and the drain discharge port of the drain circuit is formed above the uppermost position of the back pressure chamber. It has been configured.

[0008]

[Action]

 When the working fluid is supplied to the pressure receiving chamber, the fluid pressure in the clutch engagement direction acts on the piston, and at the same time, the supply of the working fluid to the back pressure chamber is stopped. At this time, the working fluid in the back pressure chamber passes through the drain circuit and escapes from the drain outlet. It can be prevented. Therefore, sufficient and accurate fluid pressure can be applied to the piston.

Further, since the drain discharge port of the drain circuit is formed above the uppermost position of the back pressure chamber, the fluid pressure is reduced when the supply of the working fluid to the back pressure chamber is stopped. The formed portion is drained, but the atmospheric pressure portion does not all escape into the back pressure chamber and the drain circuit. Therefore, it does not take time to re-supply the working fluid to the back pressure chamber, and the working response of the piston can be speeded up.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a main part of an automatic transmission according to an embodiment. In the figure, 1 indicates an output shaft. That is, the rotational force input to the automatic transmission from the engine output shaft (not shown) via the torque converter is changed by the planetary gear mechanism and then output from the output shaft 1 to the drive wheels.

[0012] The planetary gear mechanism includes a carrier including a sun gear, an internal gear, and a pinion gear that meshes with the sun gear and the internal gear at the same time. Alternatively, the output rotation speed is changed with respect to the input rotation speed by driving.

A clutch (not shown) is used as one means for fixing or driving each element that constitutes this planetary gear mechanism, and the clutch drum 20 that constitutes this clutch (for example, an overrun clutch) is It is rotatably supported by a fixed member 30 fixed to the mission case 3. In this embodiment, the clutch drum 20 is composed of a drum outer 20a and a drum inner 20b, and includes an inner circumference of the drum outer 20a and a rotating member (not shown) provided inside the clutch drum 20. A plurality of clutch plates (not shown) are provided between them, and the clutch plates are fastened or released by the piston 4 provided in the clutch drum 20.

The piston 4 is operated by hydraulic pressure (working fluid pressure), and a pressure receiving chamber 4 a that applies hydraulic pressure in the clutch engaging direction to the piston 4 is formed between the piston 4 and the clutch drum 20. ing. A supply oil passage 40 for supplying oil to the pressure receiving chamber 4a is formed in the fixed member 30, and the supply oil passage 40 is communicated with the pressure receiving chamber 4a through an oil supply hole 41 formed in the drum inner 20b. ing.

Further, a centrifugal cancel piston 5 and a return spring 6 which prevent the piston 4 from being engaged by centrifugal hydraulic pressure are provided in the clutch drum 20 so as to face the piston 4. A back pressure chamber 4b that applies a hydraulic pressure in the clutch releasing direction to the piston 4 is formed between the piston 4 and the centrifugal cancel piston 5.

A drain circuit 43 for releasing hydraulic pressure is communicated with the back pressure chamber 4b through a drain hole 42 formed in the drum inner 20b when the piston 4 is engaged. The drain circuit 43 is formed in the fixing member 30 and the mission case 3, and the drain discharge port 44 of the drain circuit 43 is formed above the uppermost position H of the back pressure chamber 4b. . The drain discharge port 44 is open to a space inside the mission case 3.

A reference numeral 7 in the drawing is, for example, a clutch that constitutes a low-and-reverse clutch, and has a structure for fixing the clutch drum 20 to the mission case 3.

Next, the operation of the embodiment will be described.

When oil is supplied to the pressure receiving chamber 4a from the oil supply passage 40 through the oil supply hole 41, hydraulic pressure in the clutch engaging direction acts on the piston 4, and the piston 4 engages the clutch to operate the clutch plate. Conclude. When the clutch is engaged, the hydraulic pressure in the back pressure chamber 4b is drained. At this time, the oil in the back pressure chamber 4b passes through the drain hole 42, the drain circuit 43, and the drain discharge port 44, but since the drain circuit 43 is formed in the fixing member 30, the oil from the drain circuit 43 is discharged. It is possible to prevent air leaks and air inclusions. Therefore, a sufficient and accurate working pressure can be applied to the piston 4.

Further, since the drain discharge port 44 of the drain circuit 43 is formed above the uppermost position H of the back pressure chamber 4b, when the hydraulic pressure of the back pressure chamber 4 is drained, In the pressure chamber 4b and the drain circuit 43, the oil corresponding to the atmospheric pressure is accumulated, and the oil in the back pressure chamber 4b and the drain circuit 43 does not all escape. Therefore, it does not take time to re-supply the oil to the back pressure chamber 4b, and the actuation response of the piston 4 can be speeded up.

Although the embodiment of the present invention has been described above with reference to the drawings, the specific configuration is not limited to this embodiment.

[0022]

[Effect of device]

 As described above, in the automatic transmission of the present invention, since the drain circuit of the back pressure chamber is formed in the case or the fixing member, it is possible to prevent the working fluid from leaking from the drain circuit and the mixing of air. Therefore, sufficient and accurate working pressure can be applied to the piston.

Since the drain outlet of the drain circuit is formed above the uppermost position of the back pressure chamber, the back pressure chamber is filled with the working fluid when releasing the back pressure. Can be maintained. Therefore, it is possible to obtain the effect that the operation response of the piston can be speeded up.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a main part of an automatic transmission according to an embodiment.

[Explanation of symbols]

 20 clutch drum (rotary drum) 3 mission case 30 fixing member 4 piston 4a pressure receiving chamber 4b back pressure chamber 43 drain circuit 44 drain discharge port 5 centrifugal cancel piston H top position

Claims (1)

[Scope of utility model registration request] 1. A rotary drum is supported by a case or a fixed member fixed to the case, and a pressure receiving chamber for applying a working fluid pressure in a clutch engaging direction to a piston provided in the rotary drum is a piston and the rotary drum. A back pressure chamber that is formed between the piston and a centrifugal cancel piston and that applies a working fluid pressure in the clutch releasing direction to the piston, is connected to the back pressure chamber in the automatic transmission. A drain circuit is formed in the case or the fixing member, and the drain outlet of the drain circuit is formed above the uppermost position of the back pressure chamber. .