Cushion plate

Abstract

A cushion plate is provided, for example, between a piston of a hydraulic servo and an adjacent friction plate in a frictional engagement element of an automatic transmission. The cushion plate is deflected by a pressing force of the piston to absorb an engagement shock. The cushion plate includes a main body portion formed into a belleville-spring shape, and a plurality of pawls that extend from the outer periphery of the main body for spline engagement with a member that is splined to, for example, the friction plate. A side wall of each pawl is formed with a curved recess extending circumferentially of the cushion plate and located adjacent the juncture (base) of the pawl at the outer periphery of the main body.

Description

[0001] This application claims priority of Japanese Patent Application No. 2004-163896 filed Jun. 1, 2004. The disclosure of Japanese Patent Application No. 2004-163896 filed on Jun. 1, 2004 including the specification, drawings and abstract is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a cushion plate used as a buffer in a multi-plate frictional engagement element provided in, for example, an automatic transmission of a vehicle. Specifically, the present invention relates to a cushion plate in which stress concentration is reduced when it is deflected. [0004] 2. Description of the Related Art [0005] Vehicular automatic transmissions utilize a multi-plate clutch or a multi-plate brake for changing a power transmission path within the transmission mechanism. In the multi-plate clutch or brake, movement of a piston of a hydraulic servo (actuator) is controlled based on the press...

AI Technical Summary

Benefits of technology

[0011] Accordingly, It is an object of the present invention to provide a cushion plate having pawls and designed to prevent abrasion, in which stress concentration at a base portion of the pawls is reduced.

[0012] According to a first aspect of the present invention, a curved recess is formed at a base portion of a pawl so as to create a circumferentially extending indentation, thereby reducing concentration of stress at the base portions of the pawls and improving durability of the cushion plate.

[0013] According to a second aspect of the present invention, the recesses are formed radially outward of the outer periphery of the plate main body, thereby avoiding a reduction in the radial dimension of the plate body. Thus, it is possible to prevent generation of a relatively large concentration of stress at the base portions of the pawls and, accordingly, the durability of the cushion plate is improved.

[0014] According to a third aspect of the present invention, the pawl is inclined in the direction from which the plate body is pressed. Therefore, when the plate body is pressed, it is possible to prevent the pawl from bending relative to the plate body. Thus, the circumferentially extending recesses prevent generation of stress at the base portion where the width of the pawl is smallest. Accordingly, the durability of the cushion plate is improved.

[0015] According to a fourth aspect of the present invention, the cushion plate is incorporation into a multi-plate frictional engagement element of an automatic transmission. Therefore, it is possible to absorb shock of engagement in the automatic transmission. Furthermore, since the pawl is splined to a member on the outer peripheral side, rotation relative to an outer friction plate is prevented. Thus, it is possible to prevent abrasion of the cushion plate.

Problems solved by technology

That is, the cushion plate may be abraded undesirably by friction with an adjacent member rotating relative to the cushion plate.

In other words, a relatively large stress concentration occurs at base portions 101g of the pawls 101b, adversely affecting durability.

Such a small contact area is undesirable when, for example, the cushion plate 101′ receives a large rotational force.

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