US2740012A

US2740012A - Snap action device

Info

Publication number: US2740012A
Application number: US397676A
Authority: US
Inventors: Argyle G Lautzenhiser
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1953-12-11
Filing date: 1953-12-11
Publication date: 1956-03-27
Anticipated expiration: 1973-03-27

Description

March 27, 1956 LAUTZENHISER SNAP ACTION DEVICE Filed Dec.

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r MM s mp w mw w L H 3 G A m .g 0. f H A 9 B 3 2 4 6 l l4 2 2 8 ll 6 6 6 I 6 0 3 4 6 O 5 5 6 6 4 United States Patent SNAP ACTION DEVICE Argyle G. Lautzenhiser, Anderson, Ind., assignor to General Motors Corporation, Detroit,.Mich., a corporation of Delaware Application December 11, 1953, Serial-No. 397,676 6 Claims. (Cl. 200-67) This invention relates to a switch and is particularly concerned with a snap action device having predeterminedand adjustable-limits for'operation' in either direction.

Specifically it is an object of the invention to provide a pressure operated switch having a snap action mechanism therein which includes adjustments for independently varying the pressure at which the switch opens and closes.

A further object of the invention is to provide a switch of the character described wherein a bowed spring is used which is pivoted against a pivot point that is longitudinally movable with respect to a pressure responsive operating member whereby the operation of the switch may be varied with respect to either one of its functionsof opening or closing. A second adjustment carried by the operating member independent of' said first mentioned adjustment may be used for'varying the other function of the switch.

A still further object of the invention is to provide a snapacting switch which is operated through a pressure sensitive diaphragm that moves a spring biased centrally located actuating rod into engagement with a snap mechanism, said. mechanism being limited in its movement in one direction by adjustment means on said rod and limited inmovement in the other direction bythe switch casing, adjustable means also being provided for adjusting the movement required to cause said snap mechanism to be actuated.

Further objects and advantages ofthe present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Fig. 1 is a vie-w partly in section of a preferred embodiment'of a pressure operated switch.

Fig. 2 is a top view of the switch shown in Fig. 1.

Fig. 3 is aview partly in section of the switch shown in Fig. l with the switch mechanism in the opposite direction.

Fig. 4 is a. view of the snap spring removed from the mechanism.

Fig. 5 is a partial view in section showing the snap mechanism in reversed position to the position shown in Fig. 1.

Snap action switches are frequently used in connection with. circuits for controlling electrical apparatus. These switches are: generally variable through adjustment to control the. opening or closing of the switch in response to changes in temperature, pressure or other conditions. In most instances, this adjustment means merely adjusts one end of the control range, that is to say the opening range, while the closing range will be a predetermined number of degrees or pounds different. In other words, the adjustment merely translates the entire operation of the switch from one range to another.

In the present switch, I have provided a device which includes an. adjustment for both the opening and closing ofthe switch mechanism. in response to conditions external of the switch whereby the spread or range of the switch may-be varied within predetermined limits independentof-the opening or closing setting. Thus the opening and, closing range of the switch may be narrow or broadwhile the opening or closing pressure may be held constant or varied. The ability to adjust the switch in the manner noted makes it very flexible in its application and makes it particularly adaptable for use in connection with pressure regulation. It is to be understood that the same switch may be actuated by means other than pressure responsive means with equal satisfaction.

Referring to the drawings, Fig. 1 shows a preferred embodiment of the switch 20 which includes a metal casing 22, a body of dielectric material 24 forming the main body of the switch and a bottom closure member 26. The closuremember 26 holds a pressure diaphragm 28 in place-against the body 24 by gripping the diaphragm circumferentially around the edge thereof. The diaphragm is bent back upon the closure member 26 as noted at 30 and then the casing 22 is spun over the edge of the closure member 26 to integrate the structure. The same general method of assembly is used at the other end of the casing 22, that is, spinning the edge of the casing 22 over the body member 24 to firmly hold the body member 24 within the casing.

Centrally located in the body member 24 is a bore 32 through which an operating shaft 33 passes. The shaft 33 includes a key 34 thereon which fits within a groove 36 in the bore 30 whereby the shaft 33 is prevented from turning within the bore while being freely slidable therein. One end of the shaft 33 includes a large diameter abutment 38which engages the diaphragm 28. T he shaft 33 is normally biased toward the diaphragm by means of spring 40 which fits within an annular recess in the body which bears that forms one end of a fitting 39 for a pressure tube (not shown) leading to a source of pressure.

It israpparent that when pressure is applied through the fitting.39 that it causes the diaphragm 28 to move away from the abutment for moving the abutment 38 and its attached shaft. 33 toward the left (Fig. 1) while simultaneously compressing the spring 40.

A contact member 44 is screw threaded into the body 24 and acts as an attachment means for two apertured

leaf springs

46 and 48 that fit over the shaft 33. 46 engagesthe contact member 44 in COndLlC'lr? relation tact. member 44 and insulates the leaf spring 43 therefrom. In this connection, leaf spring 43 may have an extension or conducting part 52 thereon which leads to a second contact member 54 which is screw threaded into the body member 24 and forms the other side of the circurt.

The

leaf springs

46 and 48 each include contacts and 58' at the free extremities thereof respectively and when in completely free position, these two leaf springs are substantially parallel with

contacts

56 and 58 in mating relation. The outward movement of leaf spring 46 is. limited. by an adjustment member 60 screw threaded upon the shaft 33. The leaf spring 48 is engaged at its outer. extremity by opposite ends of a hairpin spring made of piano wire or other suitable material 62 that is shown in Fig; 4'. In the engaged position the two free ends of the spring 62 arehingedly fitted within apertures in the contact member 58 while the central portion of the spring is depressed so as to fit in a groove 64 carried by an adjustment member 66. The adjustment member 66 is screw threaded into the body 24. Thus the leaf spring 48 and its contact 58 are held in the position shown in Fig. 1 when low pressure is apparent in a device being controlled. However, when the pressure increases sufii ciently to move the diaphragm 28, the shaft 33 also moves toward the left until a shoulder 68 on the shaft engages the leaf spring 48. This movement continues until the hairpin spring 62 passes dead center position. During this entire procedure, the adjusting nut 60 is also moving toward the left so that when the leaf spring 48 snaps toward the left, due to spring 62 passing the dead center position, the

contacts

56 and 58 are engaged as shown in Fig. 3. Upon diminishing pressure in the device being controlled, the spring 40 causes the shaft 33 to move toward the right whereupon the adjusting nut 60 will engage the leaf spring 4-6 and cause both leaf springs 4t? and 43 to move concomitantly toward the right with their contacts 56 and 53 remaining in engagement until such time as the dead center positions of the leaf spring and hairpin spring 62 are exceeded whereupon the leaf spring 48 will snap toward the right to separate

contacts

56 and 58.

It is apparent that the operation of the switch may be reversed as shown in Fig. wherein the contacts are normall engaged when the pressure is low and are opened upon a rise in pressure. In this instance, the two leaf springs move as a unit with the contacts in engagement until the dead center position is passed whereupon the outermost leaf spring is snapped away from the other leaf spring to separate the contacts. In other words, the action of the switch is reversed from the action previously described.

In both embodiments the adjustment of operating characteristics of the switch is of utmost importance. It will be noted with reference to Fig. 1 that the closing of the switch may be varied by means of the adjustment screw 66. As this screw is turned into the body member 24, the groove 64 approaches the dead center position of the leaf spring 43 and hairpin spring 62 for diminishing the closing pressure required. In the same manner adjustment of the nut 60 will hasten the opening of the switch if it is screwed inwardly on the shaft. Thus it is apparent that both opening and closing limits of the switch may be varied independently of one another so that the range of operation may be varied. This is in contrast to most snap action switches which can be adjusted but wherein the range of operation is always substantially the same. For example, the usual pressure switch includes a fixed range of operation, for example, twenty pounds, and no matter what closing pressure is chosen, it will always require a drop of about twenty pounds to again open the switch. In the present instance, this range is adjustable since both the opening and closure pressures are independently adjustable.

The use of the piano wire hairpin spring 62 is another innovation in this switch wherein a very simple spring provides satisfactory snap action characteristics therein. The spring is placed under considerable pressure as noted in Fig. 2 wherein it is urged inwardly out of its normal position so as to engage the groove 64 in the adjustment screw 66. This causes a very positive snap action in both operating positions of the switch.

A cover (not shown) may be provided for covering the operating mechanism for the switch, which cover may be attached by screws threaded into the

holes

70 and 72 shown in Fig. 2.

The outermost ends of the

conductors

44 and 52 may include binding posts thereon or may include a connector element such as is shown in Fig. 1 at 76 which connector element will plug into a complementary device for making a secure and positive electrical connection.

It is apparent that while this description has been directed to a pressure operated switch, the same principles of snap action and adjustment may be used in any adjustable snap action mechanism and such mechanisms come fully within the scope of my invention.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a snap action electric switch; a pair of substantially parallel spring contact members normally in engagement with one another, an actuating means passing through both of said members at an intermediate point thereof, a shoulder on said actuating member for engaging one of said contact members, an adjustable shoulder spaced therefrom on said actuating member for engaging the other of said contact members, a wire spring engaging the extremity of one of said contact members and compressed between the said contact member and an adjustable pivot point, said wire spring normally holding said contact members in one position with respect to each other and adapted upon movement past dead center position for causing said contact members to separate, said pivot point and said second shoulder on the actuating member being independently adjustable for varying the range of operation of said switch.

2. A snap acting device comprising in combination; an operating member positioned at one end with respect to a fixed support; a fixedly positioned adjustment member spaced from the free end of said operating member and longitudinally movable in the same general direction as said operating member; a wire spring having its two ends hingedly associated with said operating member adjacent its free end and being compressed between said free end and said adjustment member to which it is hingedly associated; a reciprocally movable actuating member; a pair of spaced stop members adapted to be moved concomitantly by said actuating member, said stop members being positioned on opposite sides of said operating member and engageable therewith during movement of said actuating member for moving the operating member past dead center position with respect to said adjustment member and said wire spring, and a second adjustment means adapted to vary the position of one of said stop members with respect to said actuating member.

3. A snap acting device comprising in combination; an operating member attached at one end thereof to a fixed support; a fixedly positioned adjustment member spaced from the free end of said operating member and longitudinally movable with respect thereto; a wire spring having its two ends hingedly associated with said operating member adjacent its free end and being compressed between said free end and said adjustment member to which it is hingedly associated; a reciprocally movable actuating member through the operating member intermediate the ends thereof; a pair of spaced stop members carried by said actuating member, said stop members being positioned on opposite sides of said operating member and engagea'ble therewith during movement of said actuating member for moving the operating member past dead center position with respect to said adjustment member and said wire spring, one of said stop members being adjustable longitudinally of said actuating member.

4. A snap acting switch comprising in combination; two contact carrying members in spaced alignment with one another and each with respect to a fixed support; a fixedly positioned adjustment member spaced from the free end of one of said contact members and longitudinally movable with respect to said one of said contact members; a wire spring having its two ends hingedly associated with said one contact member adjacent its free end and being compressed between said free end and said contact member to which it is hingedly associated; a reciprocally movable actuating member; a pair of spaced stop members adapted to be moved concomitantly by said actuating member, said stop members being positioned on opposite sides of said pair of contact members and so that each stop member is engageable with one of said contact members during certain movement of said actuating member, one of said stop members being adapted to move said one contact member past dead center position with respect to said adjustment member and said wire spring, and the other stop member being adapted to move the other contact member into engagement with said one contact member and to then move both of said contact members concomitantly until said one contact member passes dead center position with respect to said spring and adjustment member, said other stop member being adjustable independently of said adjustment member.

5. A snap acting device comprising in combination; an operating member positioned at one end with respect to a fixed support; a fixedly positioned adjustment member spaced from the free end of said operating member and longitudinally movable with respect to said operating member; a wire spring having its two ends hingedly associated with said operating member adjacent its free end and being compressed between said free end and said adjustment member to which it is hingedly associated; a reciprocally movable actuating member; a, pair of spaced stop members carried by said actuating member, said stop memhers being positioned on opposite sides of said operating member and engageable therewith during movement of said actuating member for moving the operating member past dead center position with respect to said adjustment member and said wire spring, one of said stop members being adjustable upon said actuating member.

6. A snap actuating switch comprising in combination; two contact carrying members in spaced alignment with one another and each with respect to a fixed support; a

fixedly positioned adjustment member spaced from the free end of one of said contact members and longitudinally movable with respect to said one of said contact members; a wire spring having its two ends hingedly associated with said one contact member adjacent its free end and being compressed between said free end and said contact member to which it is hingedly associated; a reciprocally movable actuating member; a pair of spaced stop members carried by said actuating member, said stop members being positioned on opposite sides of said pair of contact members and so that each stop member is engageable with one of said contact members during certain movement of said actuating member, one of said stop members being adapted to move said one contact member past dead center position with respect to said adjustment member and said wire spring, and the other stop member being adapted to move the other contact member into engagement with said one contact member and to then move both of said contact members concomitantly until said one contact member passes dead center position with respect to said spring and adjustment member, said other stop member being adjustable upon said actuating member.

References Cited in the file of this patent UNITED STATES PATENTS 1,312,692 Hornung Aug. 12, 1919 1,976,843 Eskin Oct. 16, 1934 2,061,419 Ettinger Nov. 17, 1936