US2985732A - Pressure operable control device - Google Patents

Description

May 23, 1961 l. c. RUSSELL PRESSURE OPERABLE CONTROL DEVICE Filed April 6, 1959 ...frll'lll INVENTOR 12W c:

ATTORNEY United States Patent O PRESSURE OPERABLE CONTROL DEVICE Ian C. Russell, Edmonton, Alberta, Canada, assignor of one-half to Barber Machinery Limited, Edmonton, Alberta, Canada, and one-half to Engineered Oil Controls Ltd., Edmonton, Alberta, Canada Filed Apr. 6, 1959, Ser. No. 804,331

3 Claims. (Cl. 200-82) This invention relates to pressure operable protective devices for controlling operation of equipment such as pumps and the like.

In the operation of pumps, such as electric or gasoline powered oiliield pumps, it is frequently necessary to control the operation of the pump in accordance with the pressure of the fluid under treatment. Control devices for this purpose have heretofore been proposed and are in widespread use. Such existing or proposed devices frequently suffer, however, from one or more disadvantages, such as complicated and expensive construction, awkward and cumbersome layout, and lack of sensitive operation.

It is an object of this invention to provide a simple, compact, pressure operable control device for pumps and the like, such device being of sensitive and positive operation and having a satisfactory operating life.

The invention broadly resides in the provision of a control switch having a housing therefor, a body member secured to said housing, a spring-loaded piston reciprocally mounted in said body member and operable to actuate said switch, and a diaphragm engaging one end of said piston and responsive to fluid pressure to reciprocate said piston.

The invention will be ydescribed with reference to the accompanying drawing, the single figure of which is a longitudinal sectional View of a control device in accordance with the invention.

In the drawing, 1 is a switch of conventional type which is employed to control operation of equipment such as a pump. Thus, the switch may be a micro switch having an operating member 1a and a reset button 1b. However, it will be understood that various types and combinations of one or more switches may be employed depending upon the particular control desired for a specific purpose.

A cylindrical housing 2 is provided for the switch, such housing having a removable cover 3. The switch is adjustably mounted in the housing by means of a mounting block 4 to which the` switch is fixed. The mounting block is slidably carried by an adjusting screw 5 and a spring 6 on the screw holds the block against the screw head as shown.

The housing 2 has a bottom wall 7 from which projects a screw threaded axial extension 8 for iixing thereto of a tubular body member 9.

Axially mounted for reciprocation within the housing 2 and body 9 is a piston 10, which extends through bottom wall 7 of the housing.

An actuating plate 11 is screw-threadedly mounted on the end of piston within the housing 2 and is normally arranged to seat upon the inner surface of bottom wall '7, as shown, a nut 12 securing such plate in position on the piston. It will be apparent that the nut 12 and plate 11 are adjustable to vary the position of the plate longitudinally of the piston as may be required. It will also be apparent that reciprocation of the piston and plate in one direction towards the switch in housing 2 will result r'ce in engagement of the plate with the operating member 1a of the switch and consequently actuation of the switch.

Means may, if desired, be incorporated with the piston to reset the switch on reciprocation of the piston in the opposite direction. This means may comprise a screw 13 adjustably coupled to the end of the piston by means of a portion 14 or" nut 12, a collar 15 mounted on the screw 13 and clamped between the head thereof and a map ring 16, and a radially extending arm 17 carried by the collar. As shown, the arm 17 overhangs the reset button 3 and is engageable therewith to actuate the same. The end of arm 17, in resetting position, may seat upon mounting block 4.

Means for applying a pressure responsive stroke to the piston in a switch actuating direction comprises a diaphragm 18 seated upon an internal shoulder 19 adjacent the open end 19a of body 9.

Pulsation dampeniug means are associated with diaphragm 18 and include a tubular spacer 20 one end of which engages the peripheral portion of diaphragm 18 to secure it in place on shoulder 19 and the other end of which engages one side of the peripheral portion of a second diaphragm 21. A ring 22 engages the other side of diaphragm 21 and constitutes a guide for an enlarged diameter end portion 23 of the piston. The piston portion 23 extends through guide 22 and, in the normal switch-disengaged position of the piston actuating plate 11, the end of piston portion 23, which is in engagement with the axial portion of diaphragm 21, depresses the latter diaphragm as clearly shown in the drawing. The guide 22 is preferably sealed with respect to piston portion 23 as by an O-ring 24 and with respect to body 9 as by an O-ring 25. The diaphragms 18 and 21, spacer 20, and guide 22 are clamped against shoulder 19 by means of a locking nut 26 threaded to the interim surface of body 9.

Spacer 2l) provides interiorly thereof with diaphragms 18 and 21 a pulsation dampening chamber 27 lled with a hydraulic liquid 28. Chamber 27 has a zone 29 adjoining diaphragm 18 and a second zone 30 adjoining diaphragm 21, the zones being dened by a construction 31 in spacer 20 in which is threaded a screw 32 having an axial orice 33 providing restricted communication between the two zones.

The piston 10 is urged into the switch-disengaged position shown in the drawing and is normally retained in such position by a spring 34 one end of which engages the bottom wall 7 of housing 2 and the other end of which engages a plate 35 on piston 10. The plate 35 normally engages the inner surface of guide 22 and the shoulder 36 dei-ming the inner end of piston portion 23. Stop means are provided for limiting movement of the piston beyond switch actuating position in its switch actuating stroke and comprise an annular shoulder 38 on the interior wall of nut 26 in opposed relation to and engageable by the peripheral portion of plate 35.

The device is adapted to be mounted in a fluid line as by means of the screw-threaded end portion 37 whereby the diaphragm 21 is exposed to the uid under control.

In use, pump pulsations in the uid under control and applied to diaphragm 18 will be effectively damped by the hydraulic liquid in chamber 27 and by lvirtue of the restricted communication between the two zones thereof. A predetermined degree of pressure in the fluid under control will flex diaphragm 18 inwardly which, through hydraulic liquid 28 will exert a corresponding inward ilexing motion to diaphragm 21. stroke will thus be applied to piston 10i by diaphragm 21 against the action of spring 34. When the pressure in the iluid is relieved, the piston will return to non-switch A switch actuating engaging position under the action of spring 34 and, in the embodiment shown, will reset the switch.

The switch described has many advantages some of which may be set forth as follows,

(1) The piston is protected from operating uids by the diaphragms.

(2) The diaphragms are inserted from inside the body, thus eliminating external locking nuts and threads.

(3) The pulsation dampener is built in and sealed within the unit, thus eliminating external needle valves or dampening devices which can plug up or change dampening rate due to changes in viscosity of operating fluids.

(4) Sealing of the piston guide adjacent the diaphragms guards against operating failure of the diaphragrns.

(5) The piston actuating spring never fully compresses due to the mechanical stop provided.

(6) Calibration adjustments are not made by changing the spring tension but rather by rotating screws to raise or lower switch in relation to actuating plate.

(7) The device lends itself to adaption to meet various operating needs.

(S) Variable pressure differentials are readily obtainable.

I claim:

1. A pressure operable control device for controlling fluid flow comprising a closed housing having a top closure cap and a bottom wall, a tubular body member secured to said bottom Wall, a piston reciprocally mounted in said body member and having one end portion projecting through said bottom wall into said housing, a spring on said piston in said body member and urging said piston in a direction outwardly of said housing, a shoulder fixed to said piston end portion within said housing, said housing having a seat engageable by said shoulder to define the limit of spring responsive movement of said piston outwardly of said housing, a switch in said housing and having an actuating button overhanging said shoulder, said button being in freely spaced relation to said shoulder when said shoulder is in engagement with said seat and being engageable by said shoulder to actuate said switch in response to movement of said piston in a direction inwardly of said housing, means adjustably mounting said switch to vary the distance of said button from said shoulder when in seated position, a piston guide in said body member in fixed sealing relation to the inner surface thereof, said piston extending through said guide, a diaphragm seated on said guide in said body member and engaging the other end of said piston, said diaphragm being in distended condition in response to engagement by said piston when said shoulder is in seated position, said body member having an open end and an internal annular iiange adjacent said open end, a second diaphragm seated on said annular liange in spaced relation to said first diaphragm, a spacer ring in said body member engaging said two diaphragms and holding said diaphragms in seated engagement with said guide and annular flange, the space between said diaphragme forming a damping chamber therebetween, a liquid filling said damping chamber, said second diaphragm having an exposed face for engagement by fluid under control, said diaphragms being responsive to fiuid pressure to reciprocate said piston in a direction against the action of said spring.

2. A pressure operable control device as defined in claim` 1, said shoulder being screw-threadedly mounted on said piston for adjustment in an axial direction thereof, and means for locking said shoulder in any adjusted position.

3. A pressure operable control device as defined in claim 1, said switch having a reset button, and switch reset means comprising an arm fixed to said piston and overhanging said reset button, said arm being in engagement with said button when said shoulder is in seated position.

References Cited in the le of this patent UNITED STATES PATENTS 2,058,553 Beiderman Oct. 27, 1936 2,297,678 Allen Oct. 6, 1942 2,435,143 Knauth Jan. 27, 1948 2,554,266 Pauly May 22, 1951 2,730,591 Nielsen Jan.Y 10, 1956 2,800,548 Stary July 23, 1957 2,880,909 Clymer et al Apr. 7, 1959

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