US 2855473 A
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Description (OCR text may contain errors)
Oct. 7, 1958 J. RABINOW 2,855,473
FLUID OPERATED SWITCH Filed Dec. 9. 1955 T177 5 INVENTOR.
c/acob Rab/now 32 WXV/ After-neg United States Patent 2,855,473 FLUID OPERATED SWITCH Jacob Rabinow, Takoma Park, Md. Application December 9, 1955, Serial No. 552,184 7 Claims. (Cl. 20019) This invention relates to multi-contact electrical switches in which a moving fluid is used to operate the contacting members.
There are many fields in the electrical arts where high speed, multi-contact switches are of great importance. Among these are: the art of analog-to-digital converters, telemetering commutators, telephone switches, computer switches, and so on.
As is well known, most switches suitable for high speed operation have limited life and there exists a need for switches that can makeand-break a multiplicity of circuits for thousands, millions, and even billions of cycles.
In the switch described in this specification I shall describe a simple device capable of very long life and foolproof operation. The switch uses a gas or a liquid as the actuating means for the contacts, resulting in a minimum of mechanical shock an wear in the mechanism.
The main object of my invention is to produce an electrical switch capable of operating for a great number of cycles.
Another object of my invention is to produce a switch capable of operating at a very high rate of speed.
Another object of my invention is to produce a switch of relatively simple and inexpensive construction.
Still another object is the provision of high-speed switch means having a plurality of adjacent contact operable by direct fluid pressure at very high speed and in very rapid succession. A further object is the provision of a series of adjacent switches and means for delivering a jet of high-velocity fluid in rapid succession to different ones of said switches to actuate them.
According to the invention, a series of switches is provided, each switch having at least one resilient switch blade adapted to be acted on directly by a jet of fluid, which may be gas or liquid, to move said resilient blade into contact with an opposite contact element of the switch while the jet is acting on the blade, the blade disengaging itself from said contact by its own resilience or by an oppositely-directed force on said blade as soon as the jet pressure is removed. The jet may be applied to the blades in rapid succession by a moving nozzle. If the blades are arranged in a circle or on an arc, the nozzle may be a rotating one, in which case the operation may be cyclic.
The specific nature of the invention, as Well as other Fig. 5 is a schematic diagram of a modified form of theinvention.
Fig. 1 shows a schematic view of my invention. A jet of air (or other gas) is moved across a plurality of switch contacts 2, 2', and 3, 3', etc., so that it causes the various contacts to close, one after the other. This jet may be delivered by a rotating nozzle 4, supplied with air under pressure from pipe 6 through coupling 7. Because the air can be given a very high velocity as it leaves the nozzle, the operation of the switch can be made very rapid.
It will be noted that there is relatively little motion between the mating contacts 2, 2, etc. Depending on the design of the spring contact 2, a suitable amount of wipe can be designed into the mating contacts, if desired.
For many types of use, very little or no wiping action is required, and an open-circuit contact separation of only a few thousandths or V1000 of an inch is required, so that very little force or pressure is required even for high speed operation. Under these conditions, by using suitable known long-wearing contact materials, the switch can be made capable of extremely long life, in the order of millions or even billions of cycles.
Fig. 2 shows a more practical design of an air operated switch. Here two contacts, 12 and 13, are operated simultaneously by the two jets 14 and 15. This is shown by way of example only, as more than two jets may be used. Very many different arrangements of contacts may be used. The air, being non-conductive, permits isolation of each switch element, if desired.
Any suitable source of compressed air can be used, except that for long-time operation the air should be suitably cleaned. Means for doing this are now well known. An inert gas can be used instead of air and, under some circumstances, leads to improved performance of the contacts and longer life. Instead of air under pressure to operate the contacts, vacuum applied to the exhaust pipe 16 of the case 17, as shown in Fig. 2, will also produce the desired result. Finally, of course, the gas can be recirculated by a suitable pump as shown in Fig. 4. The pump is shown as a separate unit driven by the same shaft 18 that operates the switch, but normally it would be made an integral part of the switch mechanism, and the whole assembly can be totally enclosed to keep out dirt, moisture, etc.
The details of the actual contacts are shown in Fig. 3. An insulating plate which may be the back of casing 17 carries a large number of the stationary contacts 12, 13' which may be of the printed circuit variety, if desired. A multi-fingered spring member 21 is located immediately adjacent to these contacts 12' so that one finger 12 of the spring member 21 is located over each of the stationary contacts. Still further ahead of the spring is a backstop plate 19 which can be made of any suitable material and which serves a triple purpose.
This plate 19 preloads the spring fingers, so that in the open position they press lightly against the face of this plate. This prevents their oscillating freely in air and prevents accidental contact closure due to resonant vibrations.
The plate also serves to accurately position the spring contacts 12 and thus control the gap spacing between the stationary and moving contacts.
And, thirdly, the plate can be provided with holes 22 so that the air jet is interrupted between contacts, making possible a definite break before make of the contacts, if desired, even through the contacts are very close together.
All of the switches illustrated can be operated by liquid as well as gas, but the totally enclosed switch of Fig. 2 is perhaps best suited for this purpose. If the switch is operated by a liquid, such as for instance, a light machine oil, the whole case 17 can be filled with the liquid. If desired, the case can be kept substantially empty of liquid by having the oil continuously pumped out of the case and back into the nozzles.
I found in my experiments with a switch of this type, that submerginging the contacts reduced contact bounce because of the damping property of the liquid. The use of a suitable liquid will enable the switch to handle higher voltages without breakdown and will require a smaller pump to achieve satisfactory operation.
Fig. 5 shows a slightly different arrangement of my switch wherein the nozzles 26 are stationary, but an air-commutator is used to feed the air (or other fluid) to the nozzles in succession. The revolving cyclinder 27 is provided with at least one hole 28. The cylinder is closely fitted into the bored hole in the nozzle casing 29. As the shaft 31 revolves, the cylinder revolves with it. Thus the hole 28 lines up successively with passages 32 connecting the air to the nozzles in sequence.
While I show the contacts arrayed radially and the jets acting along a line parallel to the axis of rotation of the central shaft, it should be understood that radial jets can be employed with the contacts arranged at right angle to the jet axis.
In the figures of this specification, I show simple single pole-single throw switch elements for the sake of clarity. It should be obvious to the users of such switches that other contact combinations are possible as well. By using an insulating plate 19a as shown in Fig. 2a, and mounting an additional set of stationary contacts 20 on this plate, single pole-double throw action can be achieved. In general, the contact arrangements so well known in the relay art today can be used in the switches of this invention. As in the case of the relays, the stationary contacts need not be truly rigidly mounted. They can be mounted on relatively springy supports so as to provide more wipe as the contacts close and to enable the switch design to use stacks of contacts behind each other.
In Figs. 1 and 2, the fluid is shown as acting directly against the movable contacts. If desired, a flexible diaphragm 25 can be introduced between the movable contacts and the nozzles 26, as shown in Fig. 5. The fluid would then impinge on this diaphragm, and through it operate the contacts, without coming into contact with the switch elements.
In Fig. 3 the spring contact members 12 are all shown conductively connected to plate 21; however, it will be understood that these contact members, or some of them, may also be insulated from each other to provide independent control of separate circuits, where desired.
It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of my invention as defined in the appended claims.
1. An electrical switch comprising, a plurality of armately arranged insulatedly separated stationary contacts, a like plurality of conductive resilient radial finger-like contact members each extending over and in closely spaced relationship with a respective one of said stationary contacts, a nozzle for directing a fluid stream in the direction of at least one of said radial finger-like contact members, means for angularly sweeping said nozzle successively across said finger-like contact members, and means for furnishing fluid under pressure to said nozzle during the sweep thereof, whereby said finger-like contact members are successively engaged and resiliently separated from the respective stationary contacts.
2. An electrical switch comprising, a plurality of circularly arranged insulately separated stationary contacts, a like plurality of relatively thin conductive resilient radially disposed finger-like movable contacts each extending over and in closely spaced relationship with a respective one of said stationary contacts, a nozzle for directing a fluid stream in the direction of one of said movable contacts, means for continuously rotating said nozzle successively across said movable contacts, and means for furnishing fluid under pressure to said nozzle during the rotation thereof, whereby said finger-like movable contacts are successively engaged and resiliently separated from the respective stationary contacts.
3. An electrical switch comprising, a plurality of stationary contacts circularly disposed upon an insulating plate, a like plurality of relatively thin conductive resilient finger-like movable contacts secured to said insulating plate each extending radially over and in closely spaced relationship with a respective one of said stationary contacts, a nozzle for directing a fluid stream in the direction of motion of one of said movable contacts for engaging the respective stationary contact, means for continuously rotating said nozzle, successively across said movable contacts, and means for furnishing fluid under pressure to said nozzle during rotation thereof, whereby said finger-like movable contacts are successively engaged an resiliently separated from the respective stationary contacts.
4. An electrical switch comprising, a plurality of stationary contacts circularly disposed upon an insulating plate, a like plurality of relatively thin conductive resilient finger-like movable contacts secured to said insulating plate, each of said movable contacts extending radially over and being normally upturned from said insulating plate at the respective one of said stationary contacts, a nozzle for directing a fluid stream at one of said movable contacts in the direction of the respective stationary contact, means for continuously rotating said nozzle successively across said movable contacts, and means for furnishing fluid under pressure to said nozzle during rotation thereof, whereby said finger-like movable contacts are successively engaged and resiliently separated from the respective stationary contacts.
5. An electrical switch comprising, first and second parallel mutually spaced insulating plates, said first plate supporting a plurality of circularly disposed stationary contacts, a like plurality of relatively thin conductive finger-like movable contacts secured to said first insulating plate each extending radially and having a free end over a respective one of said stationary contacts, said free end of each of said movable contacts being upturned into engagement with said second insulating plate, said second insulating plate being formed with openings in the region of engagement with each of said movable contacts, a nozzle for directing a fluid stream at one of said openings in said second insulating plate toward the respective movable contact, means for continuously rotating said nozzle successively across said openings in said second insulating plate, and means for furnishing fluid under pressure to said nozzle during rotation thereof, whereby said movable contacts are successively engaged and resiliently separated from the respective stationary contacts, said second insulating plate serving to preload and preclude oscillation of said movable contacts.
6. An electrical switch in accordance with claim 5 wherein said movable contacts are formed as integral f radial extensions of a generally flat circular conductive member secured to said first insulating plate within said circularly disposed stationary contacts.
7. An electric switch in accordance with claim 5 wherein contact means are provided on said second insulating plate for engaging each of said movable contacts.
References Cited in the file of this patent UNITED STATES PATENTS 1,322,506 Austin Nov. 25, 1919 2,222,542 Robison Nov. 19, 1940 2,239,738 Russell Apr. 29, 1941 2,379,197 Stubbins June 26, 1945 2,510,552 Carroll et al. June 6, 1950 2,773,665 Berger et al Dec. 11, 1956 2,773,951 Finley et al. Dec. 11, 1956 FOREIGN PATENTS 192,704 Great Britain May 1, 1924 194,404 Great Britain May 12, 1923