US2895024A - Pressure switch - Google Patents

Description

July 14, .1959 B E. BRQWN Em 2,895,024

PRESSURE SWITCH Filed Sept. l2. 1957 'INVENTom A 5er? E. Brow/7 BY Pay f?. Dan/,a

United States Patent O PRESSURE SWITCH Ben E. Brown, Kansas City, Kans., and Roy R. Dunlap, Kansas City, Mo.

Application September 12, 1957, Serial No. 683,594

1 Claim. (Cl. 20D-82) This invention relates to an improved pressure responsive, electrical switching apparatus particularly adapted for use in controlling an electrical circuit by means of mechanism capable of withstanding and responding to high fluid pressures which may be of the order of 5,000 pounds per square inch or greater.

An important object of this invention is to provide pressure responsive, electrical switching apparatus of improved constructional details adapting the same for continued service in high pressure applications with a minimum of Wear upon the diaphragm and other parts which normally require periodic replacement.

Another important object of the invention is to provide such apparatus in Which a snap-type, split ring is employed to retain the diaphragm and sealing O-ring in place, rather than the conventional nut assembly, thereby materially simplifying the apparatus in reducing its cost of manufacture.

Another important object of the invention is to provide such apparatus in which the path of reciprocation of a diaphragm engaging plunger may be limited to narrow bounds precluding excessive flexing of the diaphragm, all by means of simple structural relationships and elements.

Another important object of the invention is to provide such apparatus wherein the plunger-actuated, switch operating arm may be readily and accurately adjusted to vary the tensioning of the biasing spring for adapting a given apparatus for employment in applications responsive to dilerent pressures, with the interrelationships between the arm and the switch and the plunger all being compensatingly adjustable.

Other important objects of the invention will be made clear or become apparent as the following description thereof progresses.

In the accompanying drawing:

Figure 1 is a top plan view of an illustrative embodiment of the apparatus contemplated by the invention, with the dust cover removed therefrom;

Fig. 2 is a cross-sectional view taken on line II-II of Fig. 1;

Fig. 3 is a cross-sectional view taken on line III- III of Fig. 1; and

Fig. 4 is a fragmentary, cross-sectional view of a modied form of the invention taken as on line II-Il of Fig. 1.

Referring now to the drawing, the improved, pressureresponsive, electrical switching apparatus contemplated by the invention is generally designated by the numeral 10. Apparatus includes a base or housing block assembly 12 having a cylindrical concavity 14 bored therein from one side thereof and a passage 16 of smaller diam- 2,895,024 Patented July 14, 1959 eter bored therein from the opposite side thereof and communicating with the concavity 14 at its innermost extremity. `Concavity 14 and passage 16 together present a passage completely through the base assembly 12 and, since the concavity 14 is of larger diameter than the passage 16 at their zone of juncture, a shoulder 18 is presented at the innermost extremity of the concavity 14.

A resilient O-ring 20, which may be of rubber or any other suitable material, is disposed within the concavity 14 against the shoulder 18. A resilient, disc-like diaphragm 22, which may be of nylon or any other' suitable material, is disposed within concavity 14 with its circumferential margin in engagement with the O-ring 20 oppositely from the shoulder 18.

A cylindrical sleeve or plug 24 having a straight bore 26 therethrough, is disposed within the concavity 14 and has an annular marginal portion 28 at the end thereof adjacent the diaphragm 22. in engagement with the latter oppositely to the O-ring 20. A circumferential groove 30 is formed in the Wall of assembly 12 dening the concavity 14 and receives a split snap ring 32 in engagement with a marginal portion of that end 34 of sleeve 24 remote from the diaphragm 22.

Since the O-ring 2l) may be compressed well beyond the point necessary to effect a static seal between the diaphragm 22 on the one side thereof and the shoulder 18 on the other side thereof, it has been found to be a relatively simple matter during manufacturing to force the sleeve 24 inwardly within concavity 14 until the ring -32 can be inserted within groove 30, whereupon such pressure may be released without breaking the mentioned static seal. This constitutes a substantial simplification over the structures that have heretofore been conventional, and it is additionally noted that the use of the split ring 32 permits the sleeve 24 to be readily removed whenever it may become necessary to replace the diaphragm 22 or the O- ring 20.

The passage 16 is threaded adjacent its outermost eX- tremity as at 36 to receive a coupling 38 by means of which the apparatus 10 is coupled with the source of iluid under pressure to Whose pressure the apparatus is to be responsive.

The bore 26 of sleeve 24 includes a stretch of predetermined dimensions and enlarged diameter at the extremity thereof adjacent the diaphragm 22, such enlarged portion of the bore 26 being identified by the numeral 40.

A plunger, generally designated 42, has a stem 44 reciprocably received within the main portion of bore 26 and an enlarged head 46 within the enlarged bore portion 40 and at the end of stem 44 adjacent the diaphragm 22. The diameter of the enlarged plunger head 46 is sufficiently smaller than the diameter of the enlarged bore portion 40 for the latter to accommodate the former. It is also significant that the thickness of the enlarged plunger head 46 is less than the depth of the enlarged bore portion 40 by a small predetermined amount, which obviously will limit and determine the extent of reciprocation of the plunger 42 in a direction away from the diaphragm 22. It is one of the important features of the apparatus 10 that the travel of the plunger 42 be thus limited in order that liexing of the diaphragm 22 greater than that required for operating the switching apparatus hereinafter to be described will be precluded.

An elongated lever arm 48 is pivoted intermediate its ends by a pin 50 carried by a bracket 52, in turn mounted on the base assembly 12 by screws 54. The arm 48 exy tends from its pivotal axis at the pin 50 in one direction across the adjacent mouth of the concavity 14 in such disposition as to engage the end 56 of plunger 42 remote from the diaphragm 22, thence onwardly to a point disposed oppositely to a shoulder ledge S formed on the base assembly 12. he arm 48 extends in the opposite direction from the pin '50 substantially across the open side of a chamber 6d formed in the base assembly 12 alongside the concavity 14.

A compression spring 62 of helical configuration is disposed within the chamber 6th and has one end 64 thereof engaged with a wall 66 defining the closed extremity of the chamber 6d. The opposite extremity of helical coil 62 carries a disc-like plate 68 adapted to be engaged by an adjustable screw 70 carried by the arm 48 adjacent that end of the latter opposite to the portion of same engaged by the plunger end 56.

An electrical switch generally designated 72, which is preferably of the type commonly available on the market under the name micro-switch, is mounted on the assembly 12 by a bracket 74 secured to the wall 66. Such electrical switch 72 includes a reciprocable actuating element 76, and there is provided on the lever arm 4S between the pivot pin 5h and the screw 7 il, a second adjustable screw element 7S adapted to operably engage the switch actuating element 76 for reciprocating the latter as the lever arm 4S is swung about pivot pin 5t) to operate the switch 72,

In order to limit the swinging movement of the lever arm under the influence of spring 62, and thereby limit the path of reciprocatory travel of the plunger 42 in the direction of the diaphragm 22, a third adjustable screw element 30 adapted to engage the ledge 58 of base assembly l2, is provided on the arm 43 adjacent that end thereof opposite the spring-engaging element 70.

Although not shown in the drawing, it will be understood that a cover plate will normally be provided for the base assembly 12 and secured to the latter by screws (not shown) receivable within threaded bores 82 in the base assembly 12.

In operation, the adjustable screw element 80 Will be set to limit the swinging movement of the lever arm 48 in the direction it is normally biased by the spring 62 to a position such that the end 56 of plunger 42 is engaged by the arm 43 and the plunger 42 is reciprocated in the direction of diaphragm 22 until the enlarged head 46 of the plunger 42 just engages the diaphragm 22 without substantial reverse flexing of the latter under conditions of no pressure being applied to the side of diaphragm 22 facing the pressure inlet coupling 38.

The adjustable screw element 7d, which engages the plate 63 carried by the spring 62, may then be adjusted relative to the arm 48 in such manner as to oppose reciprocation of the plunger 42 in a direction away from the diaphragm 22 with predetermined force; in this manner, the apparatus 1li may be adapted for response to any pressure within the limits imposed by the tensioning of spring 62 and the adjustment available with the screw element 7d. Having set the screw element 70 so that the force of pressure on diaphragm 22 transmitted to the plunger 42 will commence to swing the lever arm 48 in a direction moving the screw element 80 out of engagement with the ledge 58 only when a predetermined pressure to which the apparatus lltl is to respond, has been reached, the adjustable screw element 76 may be positioned relative to the arm 43 for reciprocating the switch operating element 76 to actuate the switch 72 in response to such sensing by the apparatus llt) of the predetermined pressure.

Manifestly, the apparatus 1d can be adjusted to vary the pressure at which it will respond by means of the adjustment elements 70 and 78.

When the pressure uid applied through coupling 38 is suicient to iiex the diaphragm 22 with a sucient r force, the plunger 42 will swing the lever arm 4S against the resisting force of spring 62 and the element 7S on arm 48 will reciprocate the switch actuating element 76 to operate the switch 72. It will be noted that the abovementioned relative dimensioning between the thickness of the plunger head 46 and the depth of the enlarged portion 4@ of bore 26, serve to limit the reciprocation of the plunger 72 and, therefore, the flexing of the diaphragm 22 under conditions of excessive pressure.

Referring now to the modification illustrated in Fig. 4, it will be seen that the structure is precisely the same as above described except for the configuration of the head 46 of the plunger 42. In this modification the enlarged head portion 46 of the plunger 42 is provided with a curved face 102 facing and engaging the diaphragm 22. rThe curved face 102 of plunger 42 virtually merges with the flat surface 103 against which the marginal edge of diaphragm 22 is seated by O-ring Ztl. This interrelation of parts insures the absence of any abrupt edges against which diaphragm 22 may be forced and the absence of any cavities of any character into which the diaphragm may be extruded by high pressures.

lt will now be apparent that the structure contemplated by the invention is ideally adapted for accomplishing all of the above mentioned and other objects of the invention including operation under conditions involving pressures of varying degrees of intensity. It will be equally clear, however, that a number of minor modifications and changes could be made from certain details of construction disclosed for illustrative purposes without departing from the true spirit and intention of the invention. Accordingly, it will be understood that the invention should be deemed limited only by the scope of the claim that follows:

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

Pressure responsive, electrical switching apparatus adapted for use with fluids under extremely high pressures comprising: a base assembly having a passage therethrough. including a pair of interconnected stretches of which one is of larger transverse cross section than the other presenting a continuous shoulder in the passage facing one extremity of the latter at the zone of juncture of the stretches, the other extremity of the passage being adapted for coupling with a source of fluid to whose pressure the apparatus is to respond; a resilient ring in said one stretch and disposed against the shoulder; a resilient diaphragm in said one stretch and having its margin disposed against the ring oppositely to the shoulder; a sleeve having a bore therethrough and an extremity with which the bore communicates disposed against the margin of the diaphragm oppositely to the ring; means holding the sleeve in said one stretch in disposition compressing the ring to form a fluid-tight seal between the diaphragm and the ring and between the ring and the shoulder; a plunger extending through the sleeve and reciprocably mounted in the bore of the latter, one extremity of the plunger being in engagement with the diaphragm intermediate the margin of the latter; an electrical switch on said base assembly having a reciprocable actuating element adapted for reciprocation along a path parallel to and laterally ofset from the path of reciprocation of said plunger; an elongated lever arm pivotally mounted intermediate its ends on said base assembly for swinging movement about an axis between extensions in the same direction of the respective paths of reciprocation of the switch actuating element and the plunger and closer to the latter than the former, said arm including parts on one side of said pivotal axis of the arm engageable with the extremity of the plunger remote from said diaphragm; first adjustable means on the arm on the opposite side of said pivotal axis of the arm engageable with said switch actuating element for reciprocating the latter as the arm is swung by reciprocation of the plunger; a helical compression spring having one extremity thereof bearing against said base assembly; second adjustable means on the arm on said 2,895,024 Y 5 6 opposite side of said pivotal axis of the arm and further References Cited in the le of this patent removed from the latter than said rst adjustable means bearing against the other extremity of said spring for UNITED STATES PATENTS yieldably biasing the arm in a direction urging the 2,268,340 Loomis Dec. 30, 1941 plunger toward the diaphragm; and third adjustable 5 2,615,102 McMath Oct. 21, 1952 means on the arm on said one side of said pivotal axis 2,716,395 Pettigrew et al. Aug. 30, 1955 of the arm and further removed from the latter than said 2,742,548 Cole Apr. 17, 1956 parts of the arm adapted to engage said base assembly 2,744,977 Lombard et al. May 8, 1956 for limiting the extent of swinging movement of the arm 2,748,219 Buchanan May 29. 1956 under the influence of the spring. 10 2,790,044 Booth Apr. 23, 1957

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