Multi-piston valve actuator

Details Multi-piston valve actuator Multi-piston valve actuator

2002-09-20

2004-04-13

Look, Edward K. (Department: 3754)

Valves and valve actuation

Fluid actuated or retarded

Pilot or servo type motor

C251S063000, C251S063500

Reexamination Certificate

active

06719263

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear actuator having a plurality of piston surfaces for providing a higher output force upon application of a pressurized fluid to a given diameter actuator. More particularly, the present invention relates to a pressurized-fluid actuator of compact size and that includes a movable cylinder having one or more axially spaced piston surfaces for applying an actuating force for movement of the cylinder in a retraction direction, and at least one additional piston surface for applying additional actuating force for moving the cylinder in an extension direction.
2. Description of the Related Art
Linear actuators incorporating pistons that move within cylinders upon application of a pressurized fluid are well known in the art and are used for many different purposes. Generally, the output force provided by such actuators can be increased either by increasing the pressure of the fluid supplied to operate the actuator, or by increasing the diameter of the piston to increase the surface area of the piston. However, some applications require the actuator to be contained within a very limited space (so that the diameter of the piston cannot be increased). In such applications, the pressure necessary to provide the required actuating force may exceed practical limits. Accordingly, an alternative design is needed that will provide the required actuating force in a limited space at a reasonable pressure.
A number of actuator constructions have been devised in an effort to respond to the shortcoming described above. Although the prior art discloses various devices for providing increased output force from a pressurized-fluid operated actuator, the devices typically either involve a complex mechanism or otherwise fail to reduce the size of the actuator sufficiently to enable its use in a confined space.
SUMMARY OF THE INVENTION
Briefly stated, in accordance with one aspect of the present invention an actuator is provided that includes a stationary cylinder of tubular form that defines an inner cylindrical surface. A movable cylinder is slidably carried within the stationary cylinder and has a rod affixed thereto, the rod extending from the movable cylinder in an axial direction relative to the stationary cylinder. The movable cylinder divides the stationary cylinder into an upper chamber and a lower chamber. The movable cylinder also includes an inner cylindrical space.
A fixed piston extends transversely across the inner cylindrical space of the movable cylinder, thereby dividing the inner cylindrical space into a first inner chamber and a second inner chamber. A first fluid conduit is in communication with the upper chamber of the stationary cylinder and with the first inner chamber of the movable cylinder. Supplying a pressurized fluid to the first fluid conduit thus initiates movement of the movable cylinder and rod in a forward direction relative to the stationary cylinder, thereby providing a rod extension stroke. A second fluid conduit is in fluid communication with the second inner chamber for moving the movable cylinder and rod in a reverse direction relative to the stationary cylinder when pressurized fluid is introduced, thereby providing a rod retraction stroke.
In accordance with another aspect of the present invention, the actuator includes a stationary cylinder containing a movable cylinder that is divided into multiple inner chambers by fixed (stationary) pistons. The inner chambers are in fluid communication with extension and retraction ports provided in the cylinder wall. Introduction of pressurized fluid into the retraction port causes the fluid pressure to act on “n” piston surface(s) to retract the movable cylinder and rod, while introduction of pressurized fluid into the extension port causes the fluid pressure to act on “n+1” axially-spaced piston surfaces to extend the movable cylinder and rod. Accordingly, the actuator provides an increased extension force without increasing the overall diameter of the actuator and without increasing the pressure of the fluid.


REFERENCES:
patent: 2675204 (1954-04-01), Johnson
patent: 3752040 (1973-08-01), Pawloski et al.
patent: 3880051 (1975-04-01), Eppler
patent: 4335744 (1982-06-01), Bey
patent: 5191825 (1993-03-01), Beneteau et al.
patent: 5368470 (1994-11-01), Manner
patent: 5375994 (1994-12-01), Friderich et al.
patent: 5483796 (1996-01-01), Ando
patent: 5660369 (1997-08-01), Gauler
patent: 6386508 (2002-05-01), Steil et al.
patent: 4320820 (1992-11-01), None

Affiliated with

Also associated with

Rating

Multi-piston valve actuator does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multi-piston valve actuator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-piston valve actuator will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3197379