Diaphragm piston valve

Details Diaphragm piston valve Diaphragm piston valve

1999-01-19

2001-05-08

Shaver, Kevin (Department: 3754)

Valves and valve actuation

Fluid actuated or retarded

Flexible wall expansible chamber reciprocating valve actuator

C251S335200, C092S100000

Reexamination Certificate

active

06227520

ABSTRACT:

BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates generally to pistons and more specifically, to an improved diaphragm piston.
Diaphragm pistons, for example, for use in a service portion of a rail pneumatic brake valve, for example, a DB-60 brake valve available from New York Air Brake Corporation, is illustrated in
FIGS. 1 and 2
. The diaphragm piston includes a rubber diaphragm
24
held between a body
20
and a plate
28
which is secured together by a post
10
having a head
12
and a threaded portion
16
which receives a nut
34
. A spring
36
is positioned between a spring seat
38
and the back side of the plate
28
. A retainer
40
, secured to the post
10
by C-ring
42
, acts as a stop for the spring seat
38
. A stem
45
is inserted into and is secured to post
10
by aligning orifices
19
and
46
and pin
47
. Stem
45
is received and guided in a bushing of a valve seat (shown in phantom). The stem
45
includes a shoulder
44
which can catch and wear the valve seat bushing.
Other than the rubber diaphragm
24
, all of the parts are metal. In that all of the parts are metal, the post
10
requires processing to create the different areas, including the threading. The number of parts increase the expense of the diaphragm piston. Also, there is no mechanism to prevent rotation of the elements relative to each other.
The present invention is a diaphragm piston having a diaphragm between a body and plate. A post integral with and extends from the body through the diaphragm and the plate. A stop is coupled to the post and limits the axial movement of the plate away from the body. A spring seat is coupled to the post. A spring is between the plate and the spring seat. The post includes a first shoulder and the stop engages the first shoulder. The stop includes an orifice shaped to move axially on the post past the first shoulder and rotate about the post and engage the first shoulder. The first shoulder has at least one circumferential recess and the orifice in the stop includes a radial tab smaller than the recess.
A first lock prevents rotation between the stop and the post. The lock includes a recess on both the stop and the plate and a key is inserted in the recess when aligned. The spring retains the key in the recess. A second lock is also provided preventing rotation between the plate and post. The second lock includes at least one pin and a recess, one of which is on the plate and one of which is on the body.
The post includes a second shoulder and the spring seat engages the second shoulder. The spring seat includes an orifice shape to move axially on the post past the second shoulder and rotate about the post and engage the second shoulder. The second shoulder for the spring seat includes a first portion having a generally first polygonal shape and a second portion having a generally second polygonal shape of more sides than the first shape. The orifice in the spring seat is shaped to move axially past the first portion of the second shoulder and rotate about the post and engage the second portion of the second shoulder. Preferably, the first polygonal shape is generally a triangular shape and the second polygonal shape is generally an hexagonal shape.
A unique relationship between the piston guide stem and valve seat is provided. A guide is integral with and extends from the body in a direction opposite from the direction the post extends from the body. A stem is loosely seated in an orifice of the guide. The stem includes a uniform diameter, with circumferentially spaced flats, which maintains guiding contacts with a bushing of a valve seat over the total travel of the piston.
Whereas the diaphragm is rubber, the body, the plate and the lock that prevents rotation between the stop are all made of plastic. The stem, spring seat and the spring are made of metal.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.


REFERENCES:
patent: 2595156 (1952-04-01), Matasovic
patent: 2876793 (1959-03-01), Vanderpoel et al.
patent: 3614055 (1971-10-01), Douglas
patent: 3874629 (1975-04-01), Fontaine
patent: 4206901 (1980-06-01), Williams
patent: 4424738 (1984-01-01), Leighton
patent: 4693267 (1987-09-01), Patterson
patent: 5294090 (1994-03-01), Winnike
patent: 5387030 (1995-02-01), Gayfer et al.
patent: 5724881 (1998-03-01), Reynolds
patent: 5941280 (1999-08-01), Hart et al.
patent: 5971498 (1999-10-01), Engle
patent: 712831 (1931-10-01), None

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