US3246094A - Delayed return pressure actuated device - Google Patents

Description

April 12, 1966 A. P. ZASKE ETAL 3,246,094

DELAYED RETURN PRESSURE ACTUATED DEVICE Filed Dec. 15, 1963 HIMH INVENTORS ATTOR/Vf) United States Patent 3,246,094 DELAYED RETURN PRESSURE ACTUATED DEVICE Arthur P. Zaske, Utica, and Gordon G. Gast, Madison Heights, Mich, assignors to Holley Carburetor Compauy, Warren, Mich, a corporation of Michigan Fiied Dec. 13, 1963, Ser. No. 330,322 4 Claims. (Cl. 200-83) This invention relates generally to pressure responsive devices, and more particularly to a type of switch which is actuated upon an increase in hydraulic or pneumatic pressure and which remains actuated for a predetermined length of time after the pressure subsides.

There are numerous applications wherein it would be advantageous to operate an electric motor by such a switch. For example, a switch of this type is included in the parent application mentioned above wherein a waste treatment system is described and illustrated.

Therefore, a general object of the invention is to provide an improved pressure-responsive device.

A more specific object of the invention is to provide such a switch which will be actuated immediately once an increase in operating pressure occurs, and which includes means for maintaining the switch closed for a predetermined length of time after the pressure has subsided.

A further object of the invention is to provide such a switch which is economical to manufacture, easy to assemble, compact in form and eflicient in operation.

Other objects and advantages of the invention will become more apparent when reference is made to the following drawing wherein:

FIGURE 1 is a cross-sectional view of a switch embodying the invention; and

FIGURE 2 is a fragmentary cross-sectional View taken along the plane of line 22 of FIGURE 1 and looking in the direction of the arrows.

Referring to the drawings in greater detail, the pressure responsive switch assembly of FIGURE 1 includes two diaphragrns 12 and 14 confined against the opposite sides of a body portion 16 by a cover 18 and a ring 20, respectively. The cover 18 may either be attached to or form a part of the housing 21 containing a chamber 22 which is subjected to changes in hydraulic or pneumatic pressures.

The ring may be fastened to the body portion 16, and the body portion 16, in turn, fastened to the cover 18 as by screws 23. As usual, each of the diaphragms 12 and 14 is preferably supported by a pair of washers 24 and 26 positioned on the opposite sides thereof, and fastened together 'by rivets 28 and 30.

The two diaphragms 12 and 14 thus form oppositely disposed chambers 32 and 34 with the annular cavities 36 and 38 formed in the body portion 16. The body portion 16 has formed therein a central passageway having two diameters 40 and 42 and an ofl-center passage 44 communicating between the two chambers 32 and 34, passage 44 including a calibrated restriction 45. A spring 46, restrained at its one end by a spring retainer 48 fixed in body 16 urges a valve 50 against the seat 52 formed at the junction of the two diameters 40 and 42 of the central passage. The spring retainer 48 includes a plurality of ports 54. Internal stops 56 and 58 may be cast or otherwise formed on the body portion 16 to limit the downward and upward movements of the upper and lower diaphragms 12 and 14, respectively.

A bottom cover 60 formed with a cavity 62 is fastened to the body portion 16 with the ring 20 confined therebetween so as to form the chamber 64 beneath the diaphragm 14. The chamber 64 contains a pair of elec- 3,246,094 Patented Apr. 12, 1966 trical contacts 66 and 68, the former being aflixed to the bottom cover 60. The other contact 68 is fixedly attached to the free end 70 of a flexible strip or blade 72, the other end 74 of which is secured in the wall 76 of the cover 60. Wire leads 78 are fixed in any suitable manner to the fixed contact 66 and the mounted end 74 to the blade 72. The blade 72 extends through or is otherwise fixed to the collar 80 of a vertically movable rod 82 positioned directly below the center of the diaphragm 14 and adapted to fit, at its upper end, into a retainer 84 attached to the rivet 36.

A cap 86 formed with an atmospheric bleed 88 is fastened to a hollow cylindrical extension 90 which may be formed on the cover 60, thus forming a chamber 92 containing a spring 94. The spring 94 is confined between lower and upper spring seats 96 and 98, the location of the lower stationary seat 96 being manually adjustable, as by an adjusting screw 100, and the upper movable seat 98 being at all times abutted against the rod 82, which extends through an opening 102 in the wall 104.

An additional annular chamber 106 is formed between the cover 18 and the upper diaphragm 12. As illustrated in FIGURE 2, a plurality of passageways 108, 169 and 110, a junction of which may be fitted with a screen or porous filter 112, provide communication between the pressure source 22 and the chamber 106. If desired, the passageways 108, 109 and 110 may be replaced by a single opening in the top face of the cover 18. In either event, the passageways or the opening must communicate with a source 22 of hydraulic or pneumatic pressure.

The wire leads 78 connect between a motor (not shown) and a power supply (not shown) through the motor switch assembly 10 so that the motor operates when the contacts 66 and 68 are closed.

That portion of the motor switch assembly which is confined between the diaphragms 12 and 14 is a completely enclosed, fluid-filled system. Depression of the diaphragm 12 by the pressure, which has increased in the upper chamber 166 via the passageways 108, 109 and 110, will force the lower diaphragm 14 downwardly by virtue of the fluid being shifted from the chamber 32 to the chamber 34 through the central passageways 42 and 48, i.e., past the spring loaded valve 50 and through the ports 54. The downward movement of diaphragm 12 will continue until the inner washer 26 of the diaphragm 12 abuts against the stops 56. Since spring 94 maintains member 84 in contact with rod 82, the associated downward movement of the lower diaphragm 14 results in movement of the movable contact 68 fixed on the end of the blade 72 downwardly into contact with the stationary contact 66, thereby completin the circuit through the loads 78 which connect with the electric motor.

It may be highly desirable that the operation of the motor continue for a predetermined length of time, say 8 to 30 seconds, after the pressure in the upper chamber 106 subsides. This is accomplished by the fact that the fluid in the chamber 34 must return to the chamber 32 through the calibrated restriction 45 when the downward flow of fluid has ceased due to the relaxation of pressure in chamber 106 and the valve 50 is again moved against the seat 52 by the spring 46. Calibration of the restriction 45 will, of course, determine the length of time required for this transfer of the fluid, and thus the time that the operation of the motor continues. Once the pressure in chamber 106 subsides, the upward movement of the lower diaphragm 14 toward the stops 58 will be effected by the spring 94, which raises the rod 82, and hence the diaphragm 14,, against the dashpot effect of the calibrated restriction 45 between the chambers 32 and 34. After the predetermined length of time, when sufficient fluid has been displaced through the calibrated restriction 45, the movable contact 68 would, of course,

have been raised off the stationary contact 66, thereby breaking the circuit and stopping the motor.

Since the blade 72 on which the movable contact :53 is mounted is bent downwardly where it engages the stem 82, additional switch opening delay can be provided if the travel of the stem 82 is suificient to straighten the blade upon closing of the switch. Inotherwords,the blade upon closing the of switch. In other words, the blade will first have to be returned to its free bent position before further upward travel of the stem 82 opens the contacts. The delay is, of course, also aiiected by the size of the restriction 45 and the force of the spring $4.

The adjustment 1% for the spring 34 is provided to compensate for a pressure head in chamber 1% which might constitute an influence on the system. It is desirable that the switch be responsive to the rise in pressure in the chamber 166 resulting from some cause other than the head pressure. The adjustment 1% is thus employed to vary the pre-load of the spring 94 depending upon the above mentioned head. It is apparent, however, that the setting of the member 100 may also be utilized simply to afiect the duration of operation of the motor.

From the above description, it should be apparent that the invention provides an apparatus 1!) which may be used in any application requiring that a switch or other mechanism, such as a valve for example, be actuated as soon as the diaphragm 12 senses a predetermined increase in pressure and wherein the mechanism must remain actuated for a predetermined length of time after the pressure build-up in the chambers 22 and 106 has subsided.

While but one modification of the invention has been illustrated and described, other modifications may, of course, be possible within the scope of the appended claims. 1

What we claim as our invention is:

1. A device adapted to be actuated upon an increase in fluid pressure and to remain actuated for a predetermined time after the actuating pressure subsides, said device comprising an intermediate body having oppositely disposed cavities formed therein so as to provide an intermediate rigid Wall, a first movable diaphragm secured to one end of said body by means of a first end cover having a recess formed therein so as to provide a first chamber between said rigid Wall and said first diaphragm and a second chamber between said first diaphragm and said first end cover, a second movable diaphragm secured to the other end of said body by means of a second end cover member having a recess formed therein so as to provide a third chamber between said rigid wall and said second diaphragm and a fourth chamber between said second diaphragm and said second end cover, a source of varying fluid pressure outside said first end cover, a passage through said first end cover member communicating said varying pressure to said second chamber, a twodiameter passageway formed in said rigid wall for providing communication between said first chamber and said third chamber, the smaller diameter of said passage serving as a valve seat, a spring-loaded valve in the larger diameter portion of said two-diameter passage normally preventing communication between said first and third chambers, a continuously open calibrated restriction formed in said rigid wall providing continuous communication between said first and said third chamber, said first and third chambers containing trapped fluid such that when said first diaphragm is actuated by an increase in said varying pressure and a predetermined pressure in said first chamber is attained said trapped fluid is transferred past said valve and to said third chamber so as to actuate said second diaphragm in the same direction that said first diaphragm was actuated, a stem member attached to said second diaphragm and extending into said fourth chamber, switch means connected to said stem member and means operatively connected to said stem member for returning said second diaphragm to its original position when said varying pressure subsides, the return of said fluid from said third chamber to said first chamber being retarded by the closing of said valve so as to cause said fluid to return through said restriction.

2. A pressure-responsive electric switch comprising a pair of pressure responsive devices, first and second chambers positioned between said wall and said pressure responsive devices, said two chambers containing a fluid, a first cover including a first recess, said first recess serving as a third chamber with one of said pressure responsive devices, a passageway in said first cover, a second cover including a second recess, said second recess serving as a fourth chamber with the other of said pressure responsive devices, said wall having annuli formed on both sides thereof for confining said pressure responsive devices against said first and second covers, a two-diameter passageway formed through said wall, said smaller diameter portion serving as a valve seat, a spring retainer fixedly attached adjacent the larger diameter opening, a piuraiity of orifices formed in said spring retainer, a valve located in said larger diameter portion of said passageway, a first spring confined between said spring retainer and said valve for urging said valve toward said valve seat, a fixed restriction formed through said intermediate wall for continual communication between said two chambers, a stem fixedly attached to one of said pair of presstem, a first contact mounted on the free end of said flexible blade, a second contact fixedly attached to said second cover adjacent said first contact, a manually adjustable spring retainer, a movable spring retainer, and a second spring confined between said manually adjustable retainer and said movable retainer, said movable spring retainer being urged against said stem by said second spring.

3. A switch as described in claim 2 wherein said intermediate wall includes stops formed on both sides thereof limiting the travel of each of said pair of pressure respon sive devices.

A switch as described in ciaim 2 wherein said passageway formed in said first cover includes a filter element confined therein.

References Cited by the Examiner UNITED STATES PATENTS 2,350,938 6/1944 Sparrow 20083 X 2,389,856 11/1945 Jones 200-34 2,777,028 1/1957 Kendall et al. 2()O83.2 3,055,994 9/1962 Lundeen -2 20034 X BERNARD A. GILHEANY, Primary Examiner.

HARRY M. FLECK, 111., Assistant Examiner,

Claims (1)

1. A DEVICE ADAPTED TO BE ACTUATED UPON AN INCREASE IN FLUID PRESSURE AND TO REMAIN ACTUATED FOR A PREDETERMINED TIME AFTER THE ACTUATING PRESSURE SUBSIDES, SAID DEVICE COMPRISING AN INTERMEDIATE BODY HAVING OPPOSITELY DISPOSED CAVITIES FORMED THEREIN SO AS TO PROVIDE AN INTERMEDIATE RIGID WALL, A FIRST MOVABLE DIAPHRAGM SECURED TO ONE END OF SAID BODY BY MEANS OF A FIRST END COVER HAVING A RECESS FORMED THEREIN SO AS TO PROVIDE A FIRST CHAMBER BETWEEN SAID RIGID WALL AND SAID FIRST DIAPHRAGM AND A SECOND CHAMBER BETWEEN SAID FIRST DIAPHRAGM AND SAID FIRST END COVER, A SECOND MOVABLE DIAPHRAGM SECURED TO THE OTHER END OF SAID BODY BY MEANS OF A SECOND END COVER MEMBER HAVING A RECESS FORMED THEREIN SO AS TO PROVIDE A THIRD CHAMBER BETWEEN SAID RIGID WALL AND SAID SECOND DIAPHRAGM AND A FOURTH CHAMBER BETWEEN SAID SECOND DISPHRAGM AND SAID SECOND END COVER, A SOURCE OF VARYING FLUID PRESSURE OUTSIDE SAID FIRST END COVER, A PASSAGE THROUGH SAID FIRST END COVER MEMBER COMMUNICATING SAID VARYING PRESSURE TO SAID SECOND CHAMBER, A TWODIAMETER PASSAGEWAY FORMED IN SAID RIGID WALL FOR PROVIDING COMMUNICATION BETWEEN SAID FIRST AND THIRD SAID THIRD CHAMBER, THE SMALLER DIAMETER OF SAID PASSAGE SERVING AS A VALVE SEAT, A SPRING-LOADED VALVE IN THE LARGER DIAMETER PORTION OF SAID TWO-DIAMETER PASSAGE NORMALLY PREVENTING COMMUNICATION BETWEEN SAID FIRST AND THIRD CHAMBERS, A CONTINUOUSLY OPEN CALIBRATED RESTRICTION FORMED IN SAID RIGID WALL PROVIDING CONTINUOUS COMMUNICATION BETWEEN SAID FIRST AND SAID THIRD CHAMBER, SAID FIRST AND THIRD CHAMBERS CONTAINING TRAPPED FLUID SUCH THAT WHEN SAID FIRST DIAPHRAGM IS ACTUATED BY AN INCREASE IN SAID VARYING PRESSURE AND A PREDETERMINED PRESSURE IN SAID FIRST CHAMBER IS ATTAINED SAID TRAPPPED FLUID IS TRANSFERRED PAST SAID VALVE AND TO SAID THIRD CHAMBER SO AS TO ACTUATE SAID SECOND DIAPHRAGM AND EXTENDING INTO SAID SAID FIRST DIAPHRAGM WAS ACTUATED, A STEM MEMBER ATTACHED TO SAID SECOND DIAPHRAGM AND EXTENDING INTO SAID FOURTH CHAMBER, SWITCH MEANS CONNECTED TO SAID STEM MEMBER AND MEANS OPERATIVELY CONNECTED TO SAID STEM MEMBER FOR RETURNING SAID SECOND DIAPHRAGM TO ITS ORIGINAL POSITION WHEN SAID VARYING PRESSURE SUBSIDES, THE RETURN OF SAID FLUID FROM SAID THIRD CHAMBER TO SAID FIRST CHAMBER BEING RETARDED BY THE CLOSING OF SAID VALVE SO AS TO CAUSE SAID FLUID TO RETURN THROUGH SAID RESTRICTION.

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