Dual diaphragm three position actuator

• US 4,831,915 A
• Filed: 07/15/1988
• Issued: 05/23/1989
• Est. Priority Date: 12/15/1986
• Status: Expired due to Term

• Current Assignee: AVM Industries, Inc.
• Original Assignee: Maremont Corporation (Meritor, Inc. (Nevada))
• Inventors: Roach, Jack R.
• Primary Examiner(s): Look, Edward K.
• Application Number:
  US07/220,928
• Time in Patent Office: 312 Days
• Field of Search: 92/48, 92/49, 92/50, 91/167 R
• US Class Current: 92/49
• CPC Class Codes: F01B 19/00 Positive-displacement machines or engines of flexible-wall type
• CPC Class Codes: F15B 11/123 by means of actuators with fluid-operated stops

Abstract

A dual diaphragm, multiposition vacuum actuator. Dual diaphragms in a housing define two vacuum chambers. A spring urges one diaphragm and an actuator rod extended, and the other diaphragm retracted. Vacuum in one chamber retracts the extended diaphragm and actuator rod to an intermediate position, and advances the retracted diaphragm. Vacuum added in the other chamber retracts both diaphragms and the rod as a unit to a fully retracted position.

Claims

1. An improved dual diaphragm, multiposition vacuum actuator for selectively moving an actuator rod between an extended position, a middle position and a retracted position, the improved vacuum actuator comprising:

a housing having a rod end, a rear end and a side wall, with the rod end having an aperture therein;

a first diaphragm having its periphery secured to the housing and having a first effective area, the first diaphragm being disposed between the rod end and the rear end of the housing and being selectively movable within the housing between a first position where the first diaphragm is in substantial contact with the rod end of the housing, a second position where the first diaphragm is positioned a first predetermined distance away from the rod end of the housing, and a third position where the first diaphragm is positioned a second predetermined distance still further away from the rod end of the housing;

a second diaphragm having its periphery secured to the housing and having a second effective area that is greater than the first effective area of the first diaphragm, the second diaphragm being disposed between the rear end of the housing and the first diaphragm and being selectively movable within the housing between a first position where the second diaphragm is in substantial contact with the rear end of the housing and a second position where the second diaphragm is positioned a predetermined distance away from the rear end of the housing;

stop means for defining the second position of the second diaphragm and for preventing movement of the second diaphragm away from the rear end of the housing beyond its second position;

spring means disposed within the housing and between the first and second diaphragms for urging the first and second diaphragms apart and toward their respective first positions;

the first diaphragm, the second diaphragm, and housing defining a middle, collapsible chamber between the first and second diaphragms;

the second diaphragm and housing defining a rear, collapsible chamber between the second diaphragm and the read end of the housing; and

the first diaphragm and the housing defining a rod end, collapsible chamber between the first diaphragm and the rod end of the housing;

an actuator rod having a first end and second end, and being secured, at its first end, to the first diaphragm so that the second end of the actuator road extends through the aperture in the rod end of the housing to the exterior of the housing, with the cross-sectional area of the aperture in the rod end of the housing being greater than the cross-sectional area of the actuator rod so that the interior of the rod end chamber is in communication with atmospheric pressure; and

the housing further defining a first port into the middle chamber and a second port into the rear chamber so that each of the middle chamber and the rear chamber may be selectively subjected to vacuum or to atmospheric pressure;

with the actuator rod being in its extend position and the first and second diaphragms being in their first positions, under the urging of the spring means, when the middle and rear chambers are subject to atmospheric pressure;

with the actuator rod being in its middle position and the first and second diaphragms being in their second positions when the middle chamber is subject to vacuum and the rear chamber is subject to atmospheric pressure; and

with the actuator rod being in its retracted position, the first diaphragm being in its third position and the second diaphragm being in its first position when the middle and rear chambers are both subject to vacuum.

2. The vacuum actuator as in claim 1, wherein a piston is connected with and is carried by the first diaphragm so that piston is disposed in the middle chamber and faces the second diaphragm;

wherein a support plate is connected with and is carried by the second diaphragm so that the support plate is disposed in the middle chamber and faces the piston;

wherein the piston and support plate are in contact when the first diaphragm is in its second position and the second diaphragm is in its second position and when the first diaphragm is in its third position and the second diaphragm is in its first position.

3. The vacuum actuator as in claim 2 wherein the spring means is a coil spring;

wherein one end of the coil spring abuts the piston and the other end of the coil spring abuts the support plate;

wherein the piston includes an annular side wall that extends toward the support; and

wherein the coil spring is disposed within the annular side wall of the piston.

4. The vacuum actuator as in claim 1 wherein the spring means is a coil spring.