US3233055A

US3233055A - Snap action electrical switch with adjustable differential action

Info

Publication number: US3233055A
Application number: US190593A
Authority: US
Inventors: Grover M Russell
Original assignee: Penn Controls Inc
Current assignee: Penn Controls Inc; Johnson Controls International Inc
Priority date: 1962-04-27
Filing date: 1962-04-27
Publication date: 1966-02-01
Anticipated expiration: 1983-02-01

Description

Feb. 1, 1966 G. M. RUSSELL 3,233,055

SNAP ACTION ELECTRICAL SWITCH WITH ADJUSTABLE DIFFERENTIAL ACTION Filed April 27, 1962 1; i7 15 12 INVENTOR:

United States Patent 3,233,055 SNAP ACTION ELECTRICAL SWITCH WITH ADJUSTABLE DIFFERENTIAL ACTION Grover M. Russell, Goshen, Ind., assignor to Penn Controls, Inc, a corporation of Indiana Filed Apr. 27, 1962, Ser. No. 190,593 7 Claims. (Cl. 20067) The present invention relates to positive action switches and more particularly to a positive action switch wherein the switch is thrown to one position when the actuating plunger is moved to a first position and is thrown to another position when the actuating plunger moves to a second position different from the first position.

Positive action switches or snap switches as they are commonly known in the art have been manufactured in a number of forms. Generally speaking, they consist of a flexible arm which is contacted by an actuating plunger to force the flexible arm past an over center position. As soon as the flexible arm is forced past such an over center position the construction of the switch is such that the portion of the arm carrying electric contacts will move from positive contact with a stationary contact on one side of it to contact with a stationary contact on its other side by a single positive movement known commonly in 'the art as the snap action. A positive action switch of this type is disclosed in US. Patent 2,789,173, issued April '16, 1957. When the plunger is retracted away from the flexible arm in such devices, the flexible arm again passes over its over center position which causes the flexible arm to snap the contacts carried by it back to their first position. Thus a basic characteristic of these devices is that the switching action will occur at substantially the same position of the plunger regardless of whether the plunger is traveling in one direction or the other for there is only a very small distance of a few thousandths of an inch between each side of the over c'enter position. Therefore, it is the practice at the present time to utilize more than one positive action switch whenever it is desirable to have switching in a circuit occur at different positions of the device which actu'ates the switch plunger. The present invention overcomes this problem by providing means in a single positive action switch for differential switching positions of the actuating plunger.

Thus it is an object of the present invention to provide a new and improved positive action switch.

Another object is to provide a snap action switch wherein the" switching action in one direction occurs at a different position of the actuating plunger than the switching action in the opposite direction.

' A further object is to provide adjustment means in a positive action switch of the type stated in the previous object for adjusting the distance of its actuating plunger travel between switch operation in one direction and switch operation in ,the opposite direction.

An additional object is to provide abutments connected to an actuating plunger of a positive action switch of the aforementioned type which will cause the switch to operate in one'direction when engaged by one abutment and will cause the switch to operate in the opposite direction when the switch arm is engaged by the other abutment wherein the spacing between the abutments determines the distance of plungers travel between switching action in opposing directions.

Further objects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a top view of a portion of an embodiment of the present invention with a top cover removed;

FIG. 2 is a cross sectional view of the embodiment shown in FIG. 1 taken along the line 2-2;

3,233fi Patented Feb. 1, 1966 FIG. 3 is a partial cross sectional view of the embodiment as shown in FIG. 2 with some of the operational parts shown in a different position; and

FIG. 4 is a partial cross sectional view similar to FIG. 3 but with several of the operational parts positioned diiferently than shown in FIGS. 2 and 3.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principle of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

It has been normal practice in the past to secure electrical contacts near one end of a flexible arm in a positive action switch and to secure the other end of the arm to the base of the switch with an actuating plunger slidably positioned to engage the flexible arm at some point intermediate to the contacts and the secured other end. The movement of the plunger is usually opposed by a resilient device, often a spring device, which impinges against the other side of the arm opposite the actuating plunger. Thus, when such a positive action switch is mounted in machinery or equipment so that the actuating plunger has its external end engageable by an operating mechanism, the actuating plunger is forced inwardly until a point is reached at which switching operation occurs in one direction. When the plunger is retracted, the switching operation in the opposite direction will occur substantially at the same position the plunger was in when the switching operation occurred in the first direction. There is a small variance usually present between the position of a plunger for operation of a switch in one direction and for operation in the other caused by the resilient characteristics of its flexible arm and friction. However, this variation is of the order of ten thousandths of an inch or less. Further, the variation in length of this small distance is essentially uncontrollable.

At the present time, there are many applications for positive action switches wherein it is highly desirable to have the switching operation in one direction occur at one position of the actuating plunger and the switching action in the opposite direction not occur until the actuating plunger has been withdrawn to a position which is the order of thirty thousandths to one hundred and fifty thousandths of an inch further away from the position of the plunger which causes switching operation in the first direction. Although this need is not new, no switch has been devised prior to the present invention which will provide such differential positions of the actuating plunger for operation of the switch in opposing directions. The present invention provides not only for accomplishing the opposing switching actions at differential positions of an actuating plunger but also provides means for adjusting the distance between the differential positions of the actuating plunger. Thus, my new positive action switch of which an embodiment will be described in greater detail presently may be utilized in the same way a conventional positive action switch is utilized with substantially a zero distance between the differential operating positions of the actuating plunger, or it may be set to provide for differential switching action with the distance between the differential actuating positions of the actuating plunger being adjustable.

Referring now to FIGS. 1 and 2, a snap action arm or blade 10, having a slot 11 therein of the type described in US. Patent 2,789,173, has one end secured to a post 12 by a rivet 14. The post 12 is rigidly secured in a switch base 15. The switch base 15 may be constructed of plastic or other suitable material. A blade clamp 16 in the form of a U-shaped strip of resilient material is secured to the base 15 by a screw 17. The arms of the U-shaped strip 16 have V notches cut therein to receive the edges of the blade 10.

Rigidly secured in the base 15 are a pair of electrical posts 20 and 21 to which are rigidly secured

arms

22 and 23 by

rivets

24 and 25, respectively. These posts and arms provide an electrical connection to a pair of electrical contacts 26 and 2'7 which are secured to the

arms

22 and 23, respectively. The flexible arm has a pair of

electrical contacts

28 and 29 rigidly secured to it free end and positioned to contact the

contacts

26 and 27 alternately as the movable portion of the arm is switched between its two static positions.

As shown in FIG. 2, a cover 30 encloses the top of the switch and is cemented in a recess 31 of the \base 15. An actuating plunger generally indicated at 32 is slidably mounted in an aperture 33 of the cover 30. The actuating plunger 32 consists of a cylindrical portion 34 having a forked arm 35 extending therefrom, a plug 36 threaded into the cylindrical portion 34, and a pin 37 rigidly mounted in the .plug 36 by a press-fit so that the rotational adjustment of the plug 36 determines the protrusion of the pin 37 beyond a transverse semicircular abutment 38 on the bottom of cylindrical portion 34. The transverse semicircular abutment 38 is shown by a dashed line in FIGURES 2, 3 and 4. A post 39 is rigidly secured to the cover 30 to prevent the cylindrical portion 34 from rotating in the aperture 33 by having the fork portion of the arm 35 positioned so that the post 39 is within the fork.

An aperture 49 is provided in the blade 10 to allow the pin 37 to pass therethrough and engage an abutment 41 of a passive plunger 42 which is urged toward the blade 10 by a compression spring 43 placed between the plunger and the base in a bore 44.

Having described the general structure of the embodiment of the present invention illustrated in the drawings, the operation of this embodiment will now be described in detail. FIG. 2 shows the cylindrical portion 34 and the passive plunger 42 in the position which they assume when no force is being applied to the external end of the cylindrical portion 34. With the cylindrical portion in this position, the electrical contact 28 is resting against the contact 26 to complete an electrical circuit between the

posts

12 and 20. The cylindrical portion 34 of the actuating plunger 32 is constructed of an electrical nonconductive material so that engagement of the pin 37 with the blade 11) will not create a short circuit if the external end of the plunger 32 should be engaged or grounded by structure external to the cover of the switch. As is more fully described in U.S. Patent 2,789,173, tightening of the screw 17 on the U-shaped blade clamp 16 will increase the stress on the blade 19 by forcing the arms of the clamp 16 to move closer together compressing the blade 16 therebetween. This action so stresses the blade 1% that the two halves thereof on opposite sides of the slot 11 are buckled upwardly. The degree of such buckling is adjusted by adjusting the screw 17. When the blade 10 is stressed as just described, it will stay in either the elevated position of FIG. 2 or the depressed position shown in FIG. 3.

As the actuating plunger 32 is forced downwardly to the position shown in FIG. 3, the abutment 38 will contact the upper surface of the blade 10 forcing it downwardly until that portion of the blade in contact with the abutment 38 forces the entire blade to snap to the depressed position. When this occurs, the free end of blade 10 will swing contact 28 away from contact 26 and bring contact 23 into engagement with contact 27 so that the circuit from post 12 to post is broken and a circuit is completed between post 12 and post 21. The position of the actuating plunger 32 in FIG. 3 represents the position at which the downward switching action of the blade 10 has just been accomplished.

FIG. 4 illustrates the position of the actuating plunger 32 and the passive plunger 42 just prior to the occurrence of a switching action which will bring blade 10 to its elevated position shown in FIG. 2. Thus, between the time that switching has occurred, as illustrated in FIG. 3, and the upward motion of the actuating plunger 32 to the position illustrated in FIG. 4, no switching action has occurred and the plunger has moved upwardly approximately one hundred-thousandth of an inch.

During the time that the actuating plunger 32 was moving downwardly, the pin 37 was forcing the passive plunger 42 downwardly and thus carrying abutment 41 away from the lower side of the blade 10. As the actuating plunge-r moves upwardly, the abutment 38 moves away from the top of the blade while the abutment 41 on the passive plunger 42 approaches the lower side until it contacts it as illustrated in FIG. 4. The upward force on the passive plunger 42 is provided by the compression spring 43. As soon as the abutment 41 has engaged the lower side of the blade 10 and has forced it to bulge upwardly until the blade 10 snaps to its elevated position, the

contacts

27 and 29 will be disengaged from each other and the

contacts

26 and 28 will be re-engaged as shown in FIG. 2. When the actuating plunger 32 is forced downwardly again, it must move the same approximately one hundred-thousandth of an inch while abutment 41 is being forced away from the under side of the blade and abutment 38 is being brought downwardly to contact the top side of the blade. Thus, it is read ly Seen that a differential is provided in the actuating positions of the actuating plunger for switch actuation in opposing directions.

This differential distance between the actuation positions is easily adjusted by rotating the threaded plug 36 with a screwdriver. Such adjustment varies the amount of pin protrusion by pin 37 beyond the abutment 38 and therefore controls the distance between the abutment 38 and the abutment 41. Those skilled in the art will easily recognize that there are a number of mechanical forms that could be utilized to adjustably vary the distance between two abutments such as 38 and 41 which are within the scope of the present invention. An adjustment range which varies the distance between the abutments from thirty-thousandths to one hundred and fifty-thousandths of an inch has been found satisfactory for most applications.

I claim:

1. In a snap action electrical switch,

movable contact mechanism having a contact carrying member mounted for movement between two switching positions,

said mechanism including a portion actuatable ,bi-directiona-lly through a certain distance along a certain path of travel and means biasing said actuatable portion against such actuation under conditions where said portion is actuated through a predetermined amount of said certain distance and then being effective for causing such actuation for .the remainder of such certain distance causing a snap action of said actuatable portion and snapping of said .contact carrying member between said two switching positions,

and actuator mechanism for actuating said actuatable portion,

said actuator mechanism including a first abutment positioned for engaging said actuatable portion in a first one of said bi-directions and a second abutment positioned for engaging said actuatable portion in the other of said bi-directions,

said abutments being interconnected one to the other to maintain a predetermined distance apart extending along said path of travel for movement in spaced unison during such bi-directional actuation.

2. In a positive action switch having an arm pivotally secured to a rigid structure and having a portion there of stressed to assume either of two static positions when no actuating force other than a force required to produce the positive action is applied to the arm, the combination of:

a first abutment engageable With the flexible arm to force said movable portion to one static position,

a second abutment engageable with the flexible arm to force said movable portion to the other static position, and

means connecting said abutments to cause each of said abutments to move away from the arm by a predetermined distance before the arm is contacted by the other abutment, said flexible arm assuming one or the other static position when neither abutment is applying force to said arm.

3. In a positive action switch having an arm pivotally secured to a rigid structure and having a portion thereof stressed to assume either of two static positions when no actuating force other than a force required to produce the positive action is applied to the arm, the combination of:

a member slidable relative to said arm and said rigid structure,

a first abutment cooperatively acting with said member to force said movable portion to one static position when said member moves to a given position in one direction, and

a second abutment cooperatively acting with said member to force said movable portion to the other static position when said member moves in the opposite direction by a predetermined distance, said flexible arm assuming one or the other static position when neither abutment is applying force to said arm.

4. In a positive action switch having an arm pivotally secured to a rigid structure and having a portion thereof stressed to assume either of two static positions when no actuating force other than a force required to produce the positive action is applied to the arm, the combination of:

a first abutment engageable with said arm to force said movable portion to one static position,

a second abutment engageable with said arm to force said movable portion to the other static position, said flexible arm assuming one or the other static position when neither abutment is applying force to said arm,

means interposed between said abutments to cause each of said abutments to move away from the arm by a predetermined distance before the arm is contacted by the other abutment, and

adjustment means connected to said abutment connecting means to vary the predetermined distance.

5. In a positive action switch having an arm pivotally secured to a rigid structure and having a portion thereof stressed to assume either of two static positions when no actuating force other than a force required to produce the positive action is applied to the arm, the combination of:

a member slidable relative to said arm and said rigid structure,

a first abutment cooperatively acting with said member to force said movable portion to one static position when said member moves to a given position in one direction,

a second abutment cooperatively acting with said member to force said movable portion to the other static position when said member moves in the opposite direction by a predetermined distance, said flexible arm assuming one of the other static position when neither abutment is applying force to said arm, and

adjustment means connected to at least one of said abutments and to said member to vary the predetermined distance.

6. A diflerential positive action switch comprising:

a rigid mounting structure,

a flexible arm having a portion secured to the mounting structure and having another portion stressed to assume either of two static positions when no actuating force other than a force required to produce the positive action is applied to the arm, said movable portion carrying an electrical contact,

a hole in said arm,

an electrical contact secured to said mounting structure to form an electrical connection with said contact on said movable portion when said movable portion is at one of said static positions,

an actuating member slidably mounted in said structure to bear against one side of said arm when it is forced toward said arm and having an extension portion passing freely through the hole in said arm,

a passive member slidably mounted in said structure to bear against the other side of said arm and said extension portion passing through said arm, said flexible arm assuming one or the other static position when neither member is applying a force to said arm, and

a spring connected between said structure and said passive member to urge said passive member toward said extension portion and said arm.

7. A differential positive action switch comprising:

a rigid mounting structure,

a hole in said arm,

an electrical contact secured to said mounting structure to form an electrical connection with said con- 'tact on said movable portion when said movable portion is at one of said static positions,

an actuating member slidably mounted in said structure to bear against one side of said arm when it is forced toward said arm,

an extension portion threaded into said actuating member and having a portion passing freely through the hole in said arm, said extension being rotatably adjustable to vary its distance of extension beyond said actuating member,

a passive member slidably mounted in said structure to bear against the other side of said arm and said extension portion passing through said arm, said arm assuming one or the other static positions when neither member is applying force to said arm, and

a spring mounted between said structure and said passive member to urge said passive member toward said extension portion and said arm.

References Cited by the Examiner UNITED STATES PATENTS 2,627,002 l/1953 Alvarez 2O067 2,789,173 4/1957 Kaminky 20067 FOREIGN PATENTS 551,021 2/ '1943 Great Britain.

315,715 8/1956 Switzerland.

KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

1. IN A SNAP ACTION ELECTRICAL SWITCH, MOVABLE CONTACT MECHANISM HAVING A CONTACT CARRYING MEMBER MOUNTED FOR MOVEMENT BETWEEN TWO SWITCHING POSITIONS, SAID MECHANISM INCLUDING A PORTION ACTUATABLE BI-DIRECTIONALLY THROUGH A CERTAIN DISTANCE ALONG A CERTAIN PATH OF TRAVEL AND MEANS BIASING SAID ACTUATABLE PORTION AGAINST SUCH ACTUATION UNDER CONDITIONS WHERE SAID PORTION IS ACTUATED THROUGH A PREDETERMINED AMOUNT OF SAID CERTAIN DISTANCE AND THEN BEING EFFECTIVE FOR CAUSING SUCH ACTUATION FOR THE REMAINDER OF SUCH CERTAIN DISTANCE CAUSING A SNAP ACTION OF SAID ACTUATABLE PORTION AND SNAPPING OF SAID CONTACT CARRYING MEMBER BETWEEN SAID TWO SWITCHING POSITIONS,