US3549835A - Positive action,fluidically controlled electrical switch - Google Patents

Description

United States Patent George E. Schaller Lake Hiawatha, NJ. 802,097

Feb. 25, 1969 Dec. 22, 1970 Worthington Corporation Harrison, NJ.

a corporation of Delaware Inventor Appl. No.

Filed Patented Assignee POSITIVE ACTION, FLUIDICALLY CONTROLLED ELECTRICAL SWITCH 6 Claims, 5 Drawing Figs.

US. Cl. ZOO/81.5, 137/81 Int. Cl. H0lh 35/24 Field of Search 200/8 1 BISTABLE F'LUIDIC ELEMENT [56] References Cited UNITED STATES PATENTS 3,171,915 3/1965 Johnson ZOO/81.9 3,352,488 11/1967 Greene 225/45X Primary Examiner-Robert K. Schaefer Assistant Examiner-M. Ginsburg Attorney-Daniel H. Bobis ABSTRACT: A positive action, fluidically controlled electrical switch is provided and includes a bistable fluidic element which provides first and second outputs, and first and second, mechanically interrelated expansible chamber pressure responsive means which are cooperatively associated with said fluidic element in such manner as to be effective to positively move an electrical switch between the on and off" positions thereof in response to said first and second element outputs, respectively.

'PATENTEDDEB22I970 3549.835

BISTABLE FLUiDIC IO ELEMENT /U l8 1G |2 '6\.n 16 I4 BISTABLE FLUIDIC ELEMENT BISTABLE FLVIDIC ELEMENT vsm-ucm.

POWER PUMP UNLOADER VALVE CONTROL SOLENomS FLUIDIC CIRCU'TRY ELECTRICAL INTERFACE 5W \TCH BISTABLE FLUIDIC ELEMENT GEORGE E.SCHALLER POSITIVE ACTION, FLUIDICALLY CONTROLLED ELECTRICAL SWITCH BACKGROUND OF THE INVENTION I under demanding operational conditions becomes suspect.

' More specifically, it may be understood that in many of the fluidically controlled electrical switches of the prior art, the

natural venting of the pressure responsive means which are utilized to actuate the switch is relied upon to effect one of the switch strokes, as, for example, the on to off stroke, and that no positive means are provided to maintain the switch in one of the positions thereof, as for example, the off position. Accordingly, it may be further understood that any interference with such natural venting and/or application of forces in the nature of operational vibration forces to the switch may be effective to inhibit or prevent suitable change in switch position and/or to effect an undesired change in the latter, each to obvious disadvantage.

OBJECTS OF THE INVENTION It is, accordingly, an object of this invention to provide a positive action, fluidically controlled electrical switch which employs a power strokefor both switch tum-on and switch turn-off and is thus rendered particularly reliable for use under demanding operational-conditions.

Another object of this invention is theprovision of a positive action, fluidically controlled switch which requires the use of only readily available components of relatively low cost and proven dependability in the construction thereof.

Another object of this invention is the provision of a positive action, fluidically controlled switch which, in a second embodiment thereof, provides for positive, simultaneous control of two distinct, albeit interrelated, functions.

A further object of this invention is the provision of a positive action, fluidically controlled switch which is particularly, though by no means exclusively, adapted for use in the control of the unloader valve control solenoids of compressors.

SUMMARY OF THE INVENTION As currently preferred, the positive action, fluidically controlled switch of the invention comprises a bistable fluidic element which is operable in a manner analogous to a flip-flop device in an electrical circuit and, as such, will provide first and second outputs in response to the application of first and second inputs thereto, respectively. First and second, expansible chamber pressure responsive means are provided and are mechanically interrelated in such manner that when one is expanded in response to one of said. fluidic element outputs, the other is forcibly compressed, and vice versa. The pressure responsive means are connected to the bistable fluidic element and are operable in a first condition thereof, in response to one of said element outputs, to positively move an electrical switch which is cooperatively associated with one of said pressure responsive means to a first position thereof, and, in a second condition thereof in response to the other of said element outputs, to positively move said electrical switch to a second position thereof. In each instance, the venting of the pressure responsive means which is being forcibly compressed is effected through the bistable fluidic element. In a second embodiment of the invention, a second electrical switch is cooperatively associated with the other of said expansible chamber pressure responsive means and is operable thereby simultaneously with the operation of the first-mentioned electrical switch.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the invention are believed made clear by the following detailed description thereof taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic diagram of a fluidically controlled electrical switch constructed in accordancewith the principles ofthepriorart; 1,

FIGS. 2 and 3 are schematic diagrams of a positive action fluidically controlled electrical switch constructed in accordance with the teachings of thisinvention and respectively depict the same in the two operational conditions thereof;

FIG. 4 diagrammatically illustrates the positive action fluidi v cally controlled electrical switch of the invention as applied to the control of compressor unloader valve control solenoids; and

FIG. 5 is a schematic diagram of another embodiment of the positive action fluidically controlled electrical switch of the in vention.

DESCRIPTION OF THE PRIOR ART A fluidically controlled electrical switch constructed and operable in accordance with the teachings of the prior art is depicted schematically in FIG. 1 and is briefly described hereinbelow to provide a more complete background for the description of this invention.

This prior art switch, as indicated generally at 10, comprises a bistable fluidic element 12 which is operable, as well understood by those skilled in this art, in a manner analogous to that of a flip-flop element in an electrical circuit. To this effect, the element 12 includes a power signal input 14, first and second control signal inputs as indicated at 16 and 18, first and second control signal outputs as indicated at 20 and 22, and first and second vent means cooperatively associated with said outputs and indicated respectively at 24 and 26. Briefly described, it may be understood that, with a power signal input at 14, a control signal input at 18 will effect a control signal output at 20, and/or that a control signal input at 16 will effect a control signal output at 22. The control signal output at 20 will, of course, be continuous, despite the termination of the control signal input at 18, until such time as the element is switched by the application of a control signal input thereto at 16. In like manner, the control signal output at 22 will be continuous, despite the termination of the control signal input at 16, until such time as the element 12 is switched by the application of a control signal input thereto at 18. Of additional interest here, however, is the fact that upon the cessation of the control signal input at 18 and the application of a control signal input at 16, the control signal output 20 will be vented to atmosphere through vent means 24. In like manner, the same condition will occur relative to the control signal output 22 through vent means 26 upon the cessation of the control signal input at 16 and the application of a control signal input at 18.

A conventional, fluid actuated switch which comprises an input 28, a pressure chamber 30 including pressure responsive means 32 in the nature of a diaphragm extending thereacross' and carrying a switch actuator 34, and a conventional electrical switch as indicated at 36 and including a switch actuator 38, is connected as illustrated to the control signal output 20 in such manner that the presence of a control signal at input 18, with attendant presence of a control signal at output 20, will be effective to move the diaphragm 32 and switch actuator 34 to abut switch actuator 38 and close the switch 36. In like manner, it may be understood that upon the cessation of the control signal at input 18, and upon the application of acontrol signal at input 16, the control signal output 20, and ac cordingly, the pressure chamber 30, will be vented to atmosphere through vent means 24, whereupon the diaphragm 32 will be enabled to return to the depicted position thereof to re-open the switch 36.

Of particular interest, however, with regard to this reopening of the switch 36 is the fact that the venting of chamber 30 which is essential thereto must, of necessity, occur naturally through the resiliency of the diaphragm 32 and/or the force of conventional biasing means which may be cooperatively associated therewith. Particular disadvantages of this manner of switch operation, and especially for use in the operation of solenoid operated unloader valves on large rotary or reciprocating compressors under demanding operational conditions, reside in the fact that such material venting may not always occur properly. This is to say that the introduction of foreign materials in the nature of grit or heavy oils or grease to the system may prevent such venting or, alternatively, delay the same to an extent that, in any event, the requisite prompt reopening of the switch 36 does not occur upon the cessation of the control signal input 18 and application of the control signal input at 16.

In addition, it may be understood that the operational vibrations of the machinery to be controlled may be transmitted to the chamber 30 and diaphragm 32 with the result that the switch actuator 34 may be vibrated into effective contact with switch actuator 38 to close or reclose switch 36 at a time when unloader operation is not desired.

Although a simple increase in the resistance of the diaphragm 32 to flexural movement, and/or a simple increase in the force constant of the biasing means which may be cooperatively associated therewith, may appear as a solution to the problem, it may be understood that the same would give rise to other operational difficulties in the nature of the necessity for unduly high fluidic element control pressures to operate the switch.

DETAILED DESCRIPTION OF ,THE INVENTION A fluidically controlled, push-pull electrical switch constructed in accordance with the teachings of the this invention to provide a positive action on-off" cycle, and thereby overcome the disadvantages of the prior art as discussed hereinabove, is schematically depicted in the two operational positions thereof in FIGS. 2 and 3. More specifically, the switch of the invention, as indicated generally at 40, comprises the bistable element 12 operative as described hereinabove in a manner analogous to a flip-flop element in an electrical circuit.

Switch actuation means are indicated generally at 42 and comprise fixed means or stator 44, which in turn includes leg members 46 and 48. A movable actuator arm assembly is indicated at 50 and includes arm members 52 and 54. As currently preferred, the actuator arm assembly is supported from the stator 44 with freedom for rocking movement relative to the latter.

More specifically, a diaphragm assembly which includes a nonexpansible diaphragm pan 56', and an expansible diaphragm 58 in fluid flow communication therewith, is disposed as shown relative to leg member 46 and arm 52 in such manner that the diaphragm pan 56 is fixedly supported from the said leg member and the expansible diaphragm 58 extends between the leg member 46 and arm 52 to support the latter from the former with freedomfor relative movement therebetween. In like manner, a substantially identical diaphragm assembly which includes a nonexpansible diaphragm pan 60, and an expansible diaphragm 62 in fluid flow communication therewith, is disposed as shown relative to the leg member 48 and am 54 to similarly support the latter from the former. A pivot or rocking arm 64 extends as shown from the central portion of thernovable actuator arm assembly through an aperture 66 provided therefor in the stator 44 and therefrom into a notch 68 in the fixed switch support base. Although described in some detail directly hereinabove, it may be understood that the switch actuator means 42 are of substantially the same construction as those disclosed in detail in U.S. Pat. No. 3,352,488 to G. B. Greene, and reference may, of course be had thereto if desired.

An electrical switch which may, for example, take the form of a microswitch, is indicated at 70 and includes a switch actuator 72 which is disposed as shown within the path of movement of a switch actuator 74 affixed to the upper central portion of the expansible diaphragm 58.

OPERATION In operation, and assuming the fluidically controlled switch 40 of the invention to be moved from the off position thereof, as depicted in FIG. 3, to the on" position thereof, as depicted in FIG. 2, it may be understood that each of a power signal input 14 and a control signal input 18 would be applied, as indicated by the signal arrows-in FIG. 2, to the bistable fluidic element 12, and that no control signal input 16 would be applied thereto.

As a result, a control signal output 20 would appear and be communicated as indicated to the diaphragm pan 56 and therefrom to the expansible diaphragm 58 to expand the latter. Simultaneously, the expansible diaphragm 62 would be vented as indicated to atmosphere through diaphragm pan 60, the control signal output 22 and the vent 26, there being no control signal input 16.

The expansion of the diaphragm'58 would cause the actuator arm assembly 50 to be rocked from the position thereof of FIG. 3 to the position thereof of FIG. 2 with attendant abutment between switch actuators 72 and 74 and movement of the switch 70 to the on position thereof. In addition, expansible diaphragm 62 would be forcibly vented as a result of this rocking movement of the actuator arm assembly 50 due to the compression thereof effected thereby.

If it is now desired to move the fluidically controlled switch 40 of the invention back to the ofi"position thereof as depicted in FIG. 3, it may be understood that each of a power signal input 14 and a control signal input 16 would be applied, as indicated in FIG. 3 by the signal arrows, to the bistable fluidic device 12. As a result, thelexpansible diaphragm 62 would be expanded as shown by the control signal output 22, while the expansible diaphragm 58 would be vented to atmosphere as indicated through the control signal output 20 and the vent means, 24, there being no control signal input 18. Under these conditions, the actuator arm assembly 50 would be rocked from the position of FIG. 2 to the position of FIG. 3 wherein contact between the switch actuators 72 and 74 would be broken to return the switch 70 to the off position thereof and the expansible diaphragm 58 forcibly vented to atmosphere under the compressive action of the arm 52 thereon.

By the above, it is believed made clear that the fluidically controlled switch 40 of the invention provides for positive switch action in both operational directions and is effective to positively maintain the switch 70 in the desired position thereof for so long as the proper control signal inputs are applied to bistable fluidic device 12. In addition, since each of the switch strokes is powered, it may be understood that the same will provide more rapid switch operation, of a fast snap action nature, than is provided by the prior art as discussed hereinabove.

An application of the fluidically controlled switch of the invention to the positive control of solenoid-operated compressor unloader valves is depicted diagrammatically in FIG. 4. More specifically, and as indicated therein by the labeling of the diagrammatic blocks to the exclusion of reference numerals, a vertical power pump is indicated as operatively connected to fluidic circuitry. The latter would, of course, include the bistable fluidic element 12, and the vertical power pump would be effective to provide the respective power signal input 14, and the control signal inputs l6 and 18 thereto as desired under the control of suitable fluidic signal control circuitry.

The fluidic circuitry is operatively connected as indicated to an electrical interface switch which would, of course, include the switch actuation means 42 and the microswitch 70. The control solenoids for the compressor unloader valves would be suitably connected as indicated to the interface switch for actuation therefrom to control, as indicated, the unloader valves of the compressor.

The embodiment of FIG. 5 is identical to that of FIGS. 2 and 3 with the exception that the latter includes additional switch means and illustratesthe manner in which the fiuidically controlled switch can positively control two distinct, although most probably interrelated, functions. Thus, as seen in FIG. 5, a second switch which may again take the form of a microswitch is indicated at 76 and may be seen to be operatively associated through the medium of switch actuators 78 and 80, with the expansible diaphragm 62. Accordingly, it may be understood that with the-fluidically controlled switch 40 in the position thereof of FIG. 5--which corresponds to the position thereof of FIG. 3-switch 70 may be positively maintained in the off position thereof while switch 76 may be positively maintained in the on" position thereof. Conversely, with the fluidically controlled switch 40 of FIG. 5 shifted to the switch position of FIG. 2 in the manner described in detail hereinabove, it may be understood that switch 70 will be positively turned to and maintained in the on" position thereof while switch 76 will be positively turned to and maintained in the off position thereof. Accordingly, the particular adaptability of the embodiment of FIG. 5 to the control of two functions which are to be simultaneously maintained in different modes, and rapidly and positively variable therebetween, is believed made clear.

With regard to each of the disclosed embodiments, it may be understood that since the respective microswitch or microswitches may be of almost any size, within practical limits, the switch of the invention may be effective to control very high powered electrical signals in response to very low power fluidic control signals or pulses.

Many modifications of the disclosed embodiments may, of course, be'made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Iclaim:

1. In a positive action, fluidically controlled electrical switching system, a bistable fluidic element operative to provide first and second signal outputs in response to first and second signal inputs, respuectively, switch actuation means comprising first variable volume pressure responsive means, means applying said first signal output to said first variable volume pressure responsive means for expansion thereof and comprising a second variable volume pressure responsive means, means applying said second signal output to said second variable volume pressure responsive means for expansion thereof means for venting said first and second variable volume pressure responsive means, means connecting said switch actuation means to said venting means so that when said first variable volume pressure responsive means is expanded by said first signal output said second variable volume pressure responsive means will be reduced in volume and forcibly vented through said venting means, and when said second variable volume pressure responsive means is expanded by said second signal output said first variable volume pressure responsive means will be reduced in volume and forcibly vented through said venting means, and a switch actuator cooperatively associated with one of said variable volume pressure responsive means and operable in response to changes in the volume thereof to operate an electrical switch.

2. In a positive action, fluidically. controlled electrical switching system as in claim 1 wherein, said means for venting said first and second variable volume pressure responsive means comprise first vent means in said fluidic element for venting said first signal output in the absence of said first signal input, and second vent means in said fluidic element for venting said second signal output in the absence of a second signal input whereby, in the absence of said first signal input, said first variable volume pressure responsive means may be vented through said first signal output applying means and said first vent means upon the expansion of said second variable volume pressure res o nsive means, and whereby, in the absence of said secon signal input, said second variable volume pressure responsive means may be vented through said second signal output applying means and said second vent means upon the expansion of said first variable volume pressure responsive means.

3. In a positive action, fiuidically controlled electrical switching system in claim 1 further comprising, a second switch actuator cooperatively associated with the other of said variable volume pressure responsive means and operable in response to changes in the volume thereof to operate another electrical switch.

4. In a positive action, fluidically controlled electrical switching system as in claim 1 wherein, said switch actuation means comprise means mounting said first and second variable volume pressure responsive means, wherein said switch actuation means includes means connecting said first and second variable volume pressure responsive means, said connecting means being movable, upon the expansion of said first variable volume pressure responsive means, to a first position relative to said mounting means in which said second variable volume pressure responsive means are forcibly reduced in volume by said connecting means, and said connecting means are movable, upon the expansion of said second variable volume pressure responsive means, to a second position relative to said mounting means in which said first variable volume pressure responsive means are forcibly reduced in volume by said connecting means.

5. In a positive action, fiuidically controlled electrical switching system asin claim 2 wherein,said switch actuation means comprise means mounting said first and second variable volume-pressure responsive means, and said switch actuation means includes means connecting said first and second variable volume pressure responsive means, said connecting means being movable, upon the expansion of said first variable volume pressure responsive means, to a first position relative to said mounting means in which said second variable volume pressure responsive means are forcibly reduced in volume by said connecting means, and said connecting means are movable, upon the expansion of said second variable volume pressure responsive means, to a second position relative to said mounting means in which said first variable volume pressure responsive means are forcibly reduced in volume by said connecting means.

6. In a positive action, fluidically controlled electrical switching system as in claim 5 further comprising, a second switch actuator cooperatively associated with the other of said variable volume pressure responsive means and operable in response to changes in the volume thereof to operate another electrical switch.

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