US3523677A

US3523677A - Fast acting electromagnetic gas valve

Info

Publication number: US3523677A
Application number: US786558A
Authority: US
Inventors: George G North
Original assignee: US Atomic Energy Commission (AEC)
Current assignee: US Atomic Energy Commission (AEC)
Priority date: 1968-12-24
Filing date: 1968-12-24
Publication date: 1970-08-11
Anticipated expiration: 1987-08-11

Description

Aug. 11, 1970 I I -q 3,523,677

FAST ACTING ELECTROMAGNETIC GAS VALVE I Filed Dec. 24. 1968 SOURCE PULSE SOURCE INVENTOR. GEORGE GJNOR'TH ATTORNEY United States Patent 3,523,677 FAST ACTING ELECTROMAGNETIC GAS VALVE George G. North, Santa Ana, Califi, assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Dec. 24, 1968, Ser. No. 786,558 Int. Cl. F16k 31/06 US. Cl. 251141 3 Claims ABSTRACT OF THE DISCLOSURE Eddy current repulsion in conjunction with gas pressure in a high pressure chamber are employed to rapidly open an electromagnetically latched valve and thereby deliver gas to a low pressure chamber in an extremely short response time.

BACKGROUND OF THE INVENTION The invention described herein was evolved in the course of, or under Contract W-7405-ENG-48 with the United States Atomic Energy Commission.

In various applications it is desirable to control the flow of gas from one chamber to another with extremely rapid response to a flow initiating action. For example, various electro-mechanical switches are arranged such that closure of switch contacts is effected in response to compression of a bellows by the abrupt admission of pressurized air to a low pressure chamber containing the bellows. Typically, the admission of air to the chamber is controlled by an electromagnetic valve operating between a pressurized air accumulator and the chamber. With a conventional valve of this type, a valve member is generally magnetically held or latched in closed position by means of a constant magnetic field generated by a direct current energized coil, and actuated to open position by interrupting or decreasing the coil current. However, there is a significant time delay in the opening of the valve associated with the collapse of magnetic field lines, i.e., the force holding the valve in closed position, upon abrupt interruption or decrease of the magnetizing current flowing in the coil. The opening speed of such a conventional electromagnetic valve is thus degraded, and when utilized to control the actuation of an electro-mechanical switch, is limiting upon the response time thereof. Consequently, advantages are to be gained in electro-mechanical switch applications, and elsewhere, by the provision of an electromagnetic gas valve having a materially increased opening speed.

SUMMARY OF THE INVENTION The present invention relates to an electromagnetic gas valve which employs eddy current repulsion in conjunction with gas pressure acting on the valve member to provide heretofore unattainable extremely fast opening speeds.

In the accomplishment of the foregoing, the valve of the present invention generally includes a ferromagnetic valve seat defining a port communicating low and high pressure chambers, and a ferromagnetic valve member which is normally magnetically held or latched in engagement with the seat in closing relation to the port and in opposition to pressurized gas in the high pressure chamber by a constant magnetic field generated by a direct current energized coil carried by the seat. In addition, means are provided for introducing a fast current pulse to the coil which induces an eddy current in the valve member in opposition to the pulse current and creates a repulsive force between the valve member and valve seat. The force is effective to momentarily unseat the valve member from the seat, thereby significantly reducing the 3,523,677 Patented Aug. 11, 1970 force of the direct current holding magnetic field and permitting the gas pressure in the high pressure chamber to force the valve member away from the seat to a fully open position at an extremely fast rate.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, the single figure is a sectional view taken at a diametric plane through an electromagnetic valve in accordance with the present invention, electrical components of the valve being shown in schematic.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Considering now the invention in detail with reference to the drawing, there will be seen to be provided an electromagnetic valve which generally includes means defining a valve seat about a port communicating low and high pressure chambers, preferably a hollow cylindrical valve body 11 having a transverse partition 12 separating the body interior into high and

low pressure chambers

13 and 14, the partition being provided with a central circular port 16 such that a face of the partition about the port serves as a valve seat. The high pressure chamber 13 may be variously adapted for connection to a high pressure gas source, such as a pressurized air accumulator, the chamber may comprise an accumulator, etc., depending on the particular valve application. Similarly, the low pressure chamber 14 may be adapted for connection to an element into which the flow of pressurized gas is to be controlled, the low pressure chamber may comprise such an element, or the like. In any event, for the purpose of understanding the invention it suffices to state that during operation provision is made to establish a gas pressure differential between the high and low pressure chambers on opposite sides of the partition 12.

At least the partition 12 is of ferromagnetic material, and a ferromagnetic valve member 17, preferably of circular disc configuration, is mounted for coaxial translation within the low pressure chamber 14 between a normal position of engagement with the partition in closing relation to port 16, and an actuated open position dis placed therefrom, as respectively show in full and dashed lines in the drawing. More particularly, valve member 17 is preferably provided with a stem 18 projecting coaxially therefrom, which stem extends coaxially through the port 16 and slidably through a spider bushing 19 coaxially mounted within high pressure chamber 13 so as to function as a guide. The free end of the stem is formed with an enlarged head 21 which is spaced from the distal end of the bushing with respect to partition 12 when the valve member is in its closed position of engagement therewith, and engages the bushing when the valve member is in its open position of displacement from the partition. The head thus functions as a stop for determining the fully open position of the valve member.

It will be appreciated that the pressure differential between the high and

low pressure chambers

13 and 14 establishes a force acting on the valve member 17 which would normally tend to unseat and urge same away from the low pressure side (valve seat) of partition 12 to the fully open position determined by head 21 engaging bushing 19. However, means are provided to continuously generate a magnetic field which permeates the ferromagnetic partition and valve member to thereby normally magnetically hold or latch the valve member in its closed position of engagement with the seat surface against the force exerted by the pressure differential between chambers. More particularly, to generate the magnetic holding field there is preferably provided a coil 22 which is recessed within an annular groove 23 provided in the seat surface of partition 12 concentrically about port 16, or otherwise embedded in the partition. Opposite ends of the coil are led externally, for example through a radial bore 24 communicating with the groove, into connection with a direct current source 26 serving to continuously energize the coil. A direct current magnetic field is thus continuously generated with magnetic flux encircling the circumferential axis of the coil, as indiacted by arrows 27. The flux consequently extends through the partition and valve member in linking relationship to magnetically firmly hold the valve member in closed position against the seat surface of the partition, thereby normally blocking gas flow through the port 16.

In accordance with the particularly salient aspects of the invention, means are provided for selectively generating eddy current repulsive forces between the valve member and partition to initiate unseating of the valve member, effect an attendant reduction in the holding force of the direct current magnetic field, and thereby enable the force due to the pressure differential between high and low pressure chambers to cooperatively urge the valve away from the port to open position at a very fast rate. In this regard there is preferably provided a pulse source 28 connected between the ends of coil 22 in parallel with direct current source 26 to selectively introduce fast rise time current pulses thereto. In response to each pulse, eddy currents are generated in valve member 17 in opposition to the direction of pulse current flowthrough the coil, thereby substantially instantaneously establishing a repulsive force between the seat surface of partition 12 and the valve member. The repulsive force is effective to momentarily displace the valve member from the seat surface and thus create a slight gap therebetween. By virtue of the gap there is a substantial reduction in the direct current magnetic fiux 27 linking the valve member and partition, and consequently a corresponding decrease in the magnetic force acting to hold the valve member in closed position. The force acting on the valve member due to the gas pressure differential between the high pressure and

low pressure chambers

13 and 14 is now suflicient to overcome the decreased magnetic holding force and very rapidly move the valve member to its fully open position. Gas is hence delivered through port 16 from the high pressure chamber to the low pressure chamber in an extremely abrupt manner responsive to a valve opening initiating pulse generated by pulse, source 28. Return of the valve member to closed position occurs upon reduction of the pressure differential between chambers sufliciently that the force thereof is overcome by the force of the magnetic holding field continuously generated by the coil 22. Subsequent to a build-up of the pressure differential the foregoing cycle may be repeated in response to the generation of another pulse by pulse source 28. j I i h-i 21,

It is of interest to note that the pulse source 28 may be poled to generate pulses either in opposition to, or in support of the direct current source 26, and yet in either event the eddy currents induced in the valve member are necessarily in opposition to the pulse current such that the valve member is repulsed from the seating surface of partition 12. This feature emphasizes the fact that the valve member is not actuated to open position by any decrease or interruption of the direct current energization of coil 22 by source 26, as is characteristic of the operation of conventional electromagnetic valves. In such conventional operation there is a significant time delay associated with the collapse of magnetic field lines or flux, i.e., the force holding the valve member in closed position, upon abrupt termination or decrease of the magnetizing current. The time delay, of course, degrades the opening speed of the valve. Conversely, with the valve of the present invention the opening of the valve member 17 is dependent on the extremely fast acting repulsive eddy current force induced by pulse source 28 and is not functionally related to a termination or decrease of the magnetizing current of the holding field.

Although not specifically stated hereinbefore, it will be appreciated that the valve member 17, in addition to being of ferromagnetic material, is adapted for conduction of the previously noted eddy currents induced in response to the generation of pulses by pulse source 28. In this regard, the valve member may be of a ferromagnetic material which has reasonably good conductivity, e.g., high purity iron. Alternatively, a conducting ring may be embedded in the valve member concentrically opposite the coil 22. In either case, responsive to the generation of a pulse by pulse source 28, eddy currents are induced in the valve member with sufficient magnitude to unseat same.

What is claimed is:

1. An electromagnetic gas valve comprising a ferromagnetic partition separating high and low pressure chambers having a gas pressure differential therebetween, said partition having a port for communicating said chambers,

said partition having a seat surface about said port adjacent said lower pressure chamber, a ferromagnetic valve member mounted for movement coaxially of said port between a first position of engagement with said seat surface in closing relation to said port and a second position displaced from said seat surface, means for generating a direct current magnetic field having flux linking said partition and said valve member to thereby normally hold same in said first position, and means for selectively generating eddy current repulsive forces between said valve member and said seat surface to thereby abruptly initiate movement of said valve member towards said second position in cooperation with the force of said pressure differential.

2. A valve according to claim 1, further defined by the magnetic field generating means comprising a coil embedded in said partition concentrically about said port, and a direct current source connected to opposite ends of said coil in energizing relation thereto; and by the eddy current repulsive force generating means comprising a pulse source connected to the opposite ends of said coil for selectively applying current pulses thereto.

3. A valve according to claim 2, further defined by a hollow cylindrical valve body having said partition transversely therein and defining said high and low pressure chambers, a spider bushing mounted in said high pressure chamber in coaxial relationto said port, and a stem ex tending coaxially from said valve member through said port and slidably through said bushing, said stem having an enlarged head at its free end, said head being spaced from the distal end of said bushing relative to said partition when said valve member is in said first position and engageable with said distal end when said valve member is in said second position.

References Cited UNITED STATES PATENTS 1,979,127 10/ 1934 Warrick. 2,791,394 5/1957 Matthews. 2,914,034 11/1959 Becker. 3,169,550 2/1965 Reader.

ARNOLD ROSENTHAL, Primary Examiner US. Cl. X.R.