Valves and valve actuation – Fluid actuated or retarded – Piston type expansible chamber reciprocating valve actuator
Reexamination Certificate
2000-05-04
2001-06-12
Kaufman, Joseph A. (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
Piston type expansible chamber reciprocating valve actuator
C251S062000, C251S331000, C092S062000, C092S065000
Reexamination Certificate
active
06244562
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a two-stage switching valve in which a large flow rate and a small flow rate can be obtained using a same passageway, and a multistage switching valve in which more than two different flow rates can be switched.
2. Description of the Related Art
In general, in a conventional fluid system in which a small flow rate (e.g., a few cc/min) and a large flow rate (e.g., a few L/min) is switched, a small flow rate valve and a large flow rate valve are provided in parallel, so that the two valves are selectively opened or closed. However, in the conventional arrangement, since the two valves, i.e., the large flow rate valve and the small flow rate valve, the parallel fluid passageways, and a branch connector (tee) provided at a connection portion to connect the parallel passageways are indispensable, the manufacturing cost of the parts is increased and the pipe laying requires a large space and increases the manufacturing cost. In theory, it is possible to switch the large flow rate and the small flow rate by varying the opening angle of a single valve, but it is next to impossible to precisely and instantaneously switch the flow rate, for example, between a few cc/min and a few L/min.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a switching valve in which a small flow rate and a large flow rate can be switched by a single valve or more than two different flow rates can be selectively obtained by a single valve.
To achieve the object mentioned above, according to an aspect of the present invention, there is provided a multistage switching valve comprising a valve stem which is adapted to open or close a fluid passage; a biasing means (spring) for biasing the valve stem in a direction to close the fluid passage; a plurality of pistons which are relatively slidably fitted onto the valve stem at different axial positions to provide different flow rates; a plurality of stops which are provided on the valve stem to move the valve stem in a valve opening direction opposite to the direction of the movement of the valve stem caused by the biasing means, together with the pistons when the pistons are moved in the valve opening direction; a valve opening means (pressure actuator) for exerting a pilot pressure in the valve opening direction on each piston; and a flow rate control means (a plurality of stoppers) for individually restricting the axial displacements of the pistons in the valve opening direction.
According to another aspect of the present invention, there is provided a two-stage switching valve comprising a valve stem which is adapted to open or close a fluid passage; a biasing means (spring) for biasing the valve stem in a direction to close the fluid passage; a small flow rate piston and a large flow rate piston, which are relatively slidably fitted onto the valve stem at different axial positions and are arranged in a same cylinder in a predetermined order, to provide different flow rates; a small flow rate stop and a large flow rate stop, which are provided on the valve stem to move the valve stem in a valve opening direction opposite to the direction of the movement of the valve stem caused by the biasing means, together with the small flow rate piston and the large flow rate piston when the small flow rate piston and the large flow rate piston are moved in the valve opening direction; a large flow rate pilot pressure chamber formed in the cylinder to exert a pressure in the valve opening direction on the large flow rate piston; a small flow rate pilot pressure chamber formed in the cylinder to exert a pressure in the valve opening direction on the small flow rate piston; a small flow rate valve opening means (small flow rate pressure actuator) for exerting a small flow rate pilot pressure on the small flow rate pilot pressure chamber; a large flow rate valve opening means (large flow rate pressure actuator) for exerting a large flow rate pilot pressure on the large flow rate pilot pressure chamber; a small flow rate piston restricting means (small flow rate piston stopper) for restricting the axial displacements of the small flow rate piston in the valve opening direction; and a large flow rate piston restricting means (large flow rate piston stopper) for restricting the axial displacements of the large flow rate piston in the valve opening direction.
The present invention also proposes a toggle type two-stage switching valve. In the toggle type, an increased valve opening force can be obtained for the same cylinder diameter, or a smaller diameter cylinder can be used for the same valve opening force.
According to yet another aspect of the present invention, a toggle type two-stage switching valve comprises a valve stem which is adapted to open or close a fluid passage; a biasing means (spring) for biasing the valve stem in a direction to close the fluid passage; a plurality of piston chambers which are defined in a cylinder and are spaced from one another in the axial direction of the valve stem; large flow rate pistons and small flow rate pistons, which are relatively slidably fitted onto the valve stem at different axial positions and are arranged in each piston chamber within the cylinder in the same order; small flow rate stops and large flow rate stops, which are provided on the valve stem, corresponding to the piston chambers within the cylinder, to move the valve stem in a valve opening direction opposite to the direction of the movement of the valve stem caused by the biasing means, together with the small flow rate pistons and the large flow rate pistons when the small flow rate pistons and the large flow rate pistons are moved in the valve opening direction; a small flow rate pilot pressure chamber formed in each piston chamber within the cylinder to exert a pressure in the valve opening direction on the corresponding small flow rate piston; a large flow rate pilot pressure chamber formed in each piston chamber within the cylinder to exert a pressure in the valve opening direction on the corresponding large flow rate piston; a small flow rate valve opening means (small flow rate pressure actuator) for simultaneously exerting a small flow rate pilot pressure on each small flow rate pilot pressure chamber; a large flow rate valve opening means (large flow rate pressure actuator) for simultaneously exerting a large flow rate pilot pressure on each large flow rate pilot pressure chamber; a small flow rate piston restricting means (small flow rate piston stopper) for restricting the axial displacements of at least one small flow rate piston in the valve opening direction; and a large flow rate piston restricting means (large flow rate piston stopper) for restricting the axial displacements of at least one large flow rate piston in the valve opening direction.
The small flow rate piston restricting means can be constituted, for example, by a stroke adjustment cap which is screw-engaged in the cylinder to restrict the axial displacement of the small flow rate piston in the valve opening direction. The large flow rate piston restricting means can be constituted by the large flow rate piston which is closest to the small flow rate piston. If two piston chambers are formed in the cylinder, a tandem type two-stage switching valve is obtained.
The present disclosure relates to subject matter contained in Japanese Patent Applications Nos. 11-131737 (filed on May 12, 1999) and 2000-5619 (filed on Jan. 14, 2000) which are expressly incorporated herein by reference in their entireties.
REFERENCES:
patent: 4294284 (1981-10-01), Herd
patent: 4616806 (1986-10-01), Davis
patent: 4934652 (1990-06-01), Golden
patent: 5186434 (1993-02-01), Nishimura et al.
patent: 5762086 (1998-06-01), Ollivier
patent: 5851004 (1998-12-01), Wu et al.
patent: 5906353 (1999-05-01), Someya et al.
patent: 5924672 (1999-06-01), Crochet et al.
Bonderer D A
Fujikura Rubber Ltd.
Kaufman Joseph A.
McCormick Paulding & Huber LLP
LandOfFree
Multistage switching valve, two-stage switching valve, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multistage switching valve, two-stage switching valve, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multistage switching valve, two-stage switching valve, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2468216