Brake equalizer with housing enclosing piston and shock absorber

Abstract

An improved brake equalizer apparatus for equalizing fluid pressure and damping shock waves or pressure surges in fluid lines of a fluid pressure-actuated system, such as a hydraulic brake system. The apparatus has a shorter reaction time than a conventional brake equalizer, and can be manufactured with smaller overall length and weight. An important feature of the apparatus which results in reduced brake equalizer reaction time is an improved brake equalizer piston. The piston of the invention is shorter than a conventional brake equalizer piston (the ratio of the inventive piston's length to the length of the shock absorber which it abuts is substantially less than 0.5, and is preferably equal to about 0.23). The piston of the invention is also lighter than a conventional brake equalizer piston, and is preferably made of a hard, non-compressible, self-lubricating material. The brake equalizer of the invention does not employ any O-ring or other seal between the piston and the surrounding housing along which the piston slides, thus eliminating friction that would otherwise exist between such a seal and the housing as the piston slides along the housing.

Description

FIELD OF THE INVENTIONThe invention relates to brake equalizer apparatus for equalizing fluid pressure and damping shock waves or pressure surges in fluid lines of a fluid pressure-actuated system, such as a hydraulic brake system.BACKGROUND OF THE INVENTIONDevices (sometimes referred to as "brake equalizers") have been used to equalize fluid pressure and damp shock waves and pressure surges, in fluid lines of hydraulic brake systems. Brake equalizers are described in U.S. Pat. No. 4,166,655, issued Sep. 4, 1979 to the present inventor, U.S. Pat. No. 4,220,376, issued Sep. 2, 1980 to the present inventor, and U.S. Pat. No. 5,078,455, issued Jan. 7, 1992 to Washington, for example.The brake equalizer described in U.S. Pat. No. 4,220,376 includes a rigid piston 48 attached to an elastomeric shock absorber 50. Piston 48 and shock absorber 50 are enclosed within a bore in a rigid housing 56. One end of piston 48 is exposed to fluid within chamber 42, and the other end of piston 48 abuts...

AI Technical Summary

Benefits of technology

The invention is an improved brake equalizer apparatus for equalizing fluid pressure and damping shock waves or pressure surges in fluid lines of a fluid pressure-actuated system, such as a hydraulic brake system. The inventive apparatus has a shorter reaction time than a conventional brake equalizer, and can be manufactured with smaller overall length and weight.

The inventive brake equalizer does not employ any seal (such as an O-ring seal) between the piston and the surrounding housing along which the piston slides, thus eliminating friction that would otherwise be present between such a seal and the housing as the piston slides along the housing. Besides reducing the reaction time of the brake equalizer (by reducing the piston assembly's sliding friction), elimination of seals from around the inventive piston also eliminates the need for providing oil in the volume between the sides of the piston / shock absorber assembly and the surrounding housing.

The inventive piston design allows the overall length of inventive brake equalizer to be reduced. The inventive piston design enables a preferred embodiment of the brake equalizer's housing (including body and cap portions) to have a length of 4.2 inches or even less (in contrast with the housing of U.S. Pat. No. 4,166,655 which has a preferred length of 6.4 inches).

The inventive brake equalizer design eliminates the need for a metal plate to be bonded to the elastic diaphragm which separates the piston from the variable-pressure fluid (whose pressure is to be equalized). A preferred embodiment of the inventive brake equalizer includes a screen positioned between the diaphragm and the variable-pressure fluid, to prevent contaminants (especially sharp or abrasive particles) from reaching the diaphragm and possibly penetrating through it to the piston / absorber.

Problems solved by technology

The inventor of the present application has recognized that conventional brake equalizers have several limitations, including the following: 1. they have slow reaction time, and thus are unable to equalize rapid pressure fluctuations of the type which often occur in brake air line systems; and 2. they have large overall length and weight, which renders them impractical to use in certain applications.

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