US3043928A - Snap switch - Google Patents

Description

July 10, 1962 3,043,928

J. O. ROESER SNAP SWITCH Filed March 1, 1961 2 Sheets-Sheet 1 ("x Fu i lfz 14,1 1 20 2b 52 7q I INVENTOR. F1 70 Bgol'm 0. Roeser 7e I 72 W 74 E! as I y 62 .1. o. ROESER 3,043,928

SNAP SWITCH Filed March 1, 1961 2 Sheets-Sheet 2 1 DIRECTION or MOVEMENT OF LEVER.

88) 1 pmec'now 0F MOVEMENT OF LEVER.

INVENTOR. John 0. Poeser.

United States Patent one 3,943,928 Patented July 10, 1962 3,043,928 SNAP SWITCH John O. Roeser, Park Ridge, 111., assignor to Illinois Tool Works, Inc, a corporation of Delaware Filed Mar. 1, 1961, Ser. No. 92,505 11 Claims. (Cl. 200--67) This invention relates to an open type of switch, and more particularly, it relates to a snap action open type of switch having a gang action.

Open type switches have been manufactured heretofore which have been unduly complex in number of parts, have tight manufacturing tolerances, and have not presented the reliability and vibrational resistance required in many modern-day applications. It is a general object of this invention to provide a switch which is rugged, simple to manufacture, has a minimum number of parts, and which provides good vibration resistance in field use.

It is a further object of this invention to provide a movable contact assembly having a movable member and a contact carrying member, the contact carrying member being pivoted on themovable member, there being biasing means to provide strong over-centering to provide a stable switch of the snap acting type.

It is a further object of this invention to provide a snap acting switch of the type above described wherein the pivot point for the contact carrying member moves during actuation of the switch to provide a wiping action of the contacts.

The novel features that are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof may best be understood by the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view, partially in section, illustrating one embodiment of the novel switch;

FIG. 2 is a view, partially in section, taken along lines 22 of FIG. 1;

FIG. 3 is a plan view, somewhat enlarged, of the operator mechanism used in the embodiment shown in FIGS. 1 and 2;

FIG. 4 is a view of the movable contact carrying member used in both embodiments of the switch;

FIGS. 5 and 6 are end views and plan views respectively of the force transmitting insulating member which is a part of the operator means shown in FIG. 3;

FIG. 7 is a perspective view of the fixed contact carrying member utilized in the assembly shown in FIG. 1;

FIG. 8 is a perspective view of the insulation block used in the assembly shown in FIG. 1;

FIG. 9 is a perspective view of the common terminal means used in FIG. 1;

FIG. 10 is a perspective view of the first movable member of the movable contact assembly used in the assembly shown in FIG. 1;

FIG. 11 is a front elevational View of an alternative embodiment of switch;

FIG. 12 is a detached end view of the force transmitting member of the operating means used in the embodiment shown in FIG. 11; and

FIG. 13 is an end view of the first movable member of the movable contact assembly used in the embodiment shown in FIG. 11;

FIG. 14A is a semi-diagrammatical view showing the force relationships that obtain in one-half of the assembly, which is in a stable position;

FIG. 14B is a semi-diagrammatical view showing a portion of the mechanism shown in FIG. 14A in its reversed position;

FIG. 15A is a semi-diagrammatical view showing the I reaction forces about the force transmitting members just subsequent to the tripping of the upper switch unit and prior to the tripping of the lower switch unit as the operating lever is moved upwardly.

FIG. 15B is a semi-diagrammatical representation of the forces that obtain in the mechanism, the condition being prior to tripping, both contacts being in the position shown irrFIG. 1 of the drawing. 1

As shown in the drawings, the switch unit 10 is of relatively open construction which may be denominated the skeleton type. Moreparticularly, in FIG. 1 of the drawings is shown a stack of elements in parallel array which are mounted on two upstanding pin means 12 and 14 which may be in the form of a metallic elongated eyelet having spun-over ends at .16 to maintain the assembly in stacked alignment. To insulatingly mount the eyelet from the metal members of the switch assembly 10, a tube 18 made of insulating plastic, such as nylon, is disposed in surrounding relationship to the pins 12 and 14.

A stack of relativelyelongated thin, flat members are formed with apertures for receipt of the pins 12 and 14 and are mounted thereon in spaced arrangement. As shown, there are two mirror image switch units aligned on the pins 12 and 14, the upper switch assembly having a common terminal means 20, a first fixed contact means 22, and a second fixed contact means '24. The lower switch assembly comprises a lower common terminal means 26 and the first and second fixed contact means 28 and 30 respectively. Insulation blocks 32 and 34 are interposed inthe stack to both physically separate the metallic parts and to provide electrical insulation therebetween. It will be noted that insulation block 34 is substantially similar to block 32 shown in FIG. 8 except that it is thicker.

Each of the common terminal members 20 and 26 have terminal means 20a and 26a on the free end thereof as shown on the left hand side of FIG. 1. Fixed terminal means 22, 24, 28, and 30 also have terminal means 22a,

24a, 28a, and 30a on the ends thereof, which may be offset in staggered relation as suitable and desired. The other ends of the fixed contact means (to the right in FIG. 1) mount a laminated silver insert such asshown at 22b, 24b and 28b and 30b to provide the fixed contacts of the assembly. 7

The common terminal means 26 and 20 are mirror images-of each other when mounted in the relationship shown in FIG. 1. 'As shown in FIG. 9, the lower common terminal means 26 has an angularly offset end portion 36 which is formed with acentral aperture 38 and a V- shaped transverse groove 40. The upper common terminal means 20 is similarly formed with an offset end portion 42, V-shaped notch 46 and through aperture 44. It will be noted that each of the common terminal means 20 and 26 are somewhat longer than the fixed contact members 22, 24, 30, and 2.8 and that the offset end portions, in assembly, are turned inwardly towards each other for purposes hereinafter appearing.

Two movable contact assemblies 48 are provided and are substantially identical although when mounted there are mirror image relationships involved. Only one movable contact assembly will be described, it being apparent that the same relationships obtain in both instances. The movable contact assembly essentially comprises 'a'first movable member 50, a contact carrying member 52, and a biasing means 54. The movable contact member 50 has a substantially straight portion 56 formed with a knife edge on the end thereof at 58 (see FIG. 10), an angularly offset portion 60 which is formed with a V-shaped groove 62,'and a curvilinear end portion 64. An aperture. 66

extends through all three portions of the movable member I 50 to provide clearance for the coil-spring biasing means 54 which extends therethrough as shown in FIG,- 1. The knife edge 53 of movable member 50 is mounted in the U-sha-ped in configuration having arms 68 and 70, there 'beingknife edges 72 on each end thereof. The U-shaped movable contact member 52 has a small aperture 74 lo- "cated in the bail portion of the U immediately adjacent to the slot defining the two arms 68 and 70'. A movable contact 76 is'fixedly, mounted on members 52 near the end thereof as shown in FIGS.'1 and 4.

The movable contact member 52 is maintained in pivotal relationship to the first movable member by the coil spring biasing means 54, one end of which is mounted in aperture 74, the other end being mounted in the apertures in the common terminal means such as 38 and 44. The spring 54 thus maintains the knife edges 72 in grooves 62 and knife edges 58 in grooves such as 40 and 46.

Operator means 78 for the switch essentially comprises an elongated lever means 79 (see FIG. 3) and a short insulator cylindrical grommet force transmitting member 80. The operating lever 79 is centrally located in the switch and is formed with a pair of elongated thin arms 81 and 82 which are held in position in the stack by the eyelets 14 and 12. The member 79 is relatively flexible and has an aperture 84 of predetermined diameter which is connected by a reduced diameter slot 86 which connects with the aperture defining the arms 81 and 82. The aperture '84 serves to mount the force transmitting member '80 in a manner to be hereinafter described, the neckeddown'portion 86 preventing removal of member 80 from association with member 79. The free end 88 of member 79 serves as the operating end of the lever for actuation of the switch. Y

Force transmitting member 80 may be made of insulating material such as nylon or the like and has a cylindrical body portion 90 and enlarged head portions 92 and 94. The diameter of portion 90 is less than the diameter of the aperture 84 so that there may be relative movement of the force transmitting member 80' to the lever 79. Also the heads 92 and 94 are spaced apart a greater dimension than the dimension of the thickness of material of lever 79 so as to provide a lost motion connection therebetween. The heads 92 and 94 of the force transmitting member are adapted to engage the curvilinear portion 64 of each of the first movable members to transmit actuating force to the movable'contact assemblies 48. It will be noted that the curvilinear portions slide across the face of the respective head 92 and 94 of the force transmitting member on each actuation of the switch.

The arrangement of the movable contact assembly as shown provides a stable, vibration resistant assembly, the reaction force of the movable contact in engagement with the fixed contact together with the lever relationship afforded by the spring 54 forcing the pivotal connection between the movablecontact member and the first movable member into an extremely stable position after actuation of theswitch. On the other hand, movement of the free-end 88 of lever'79 assures a quick over-centering of the pivot point to cause the movable contacts to quickly reverse their positions and snap in the other direction. The lost motion connection between the force transmitting member 80 and the'lever 79 assures simultaneousness of action in either direction when actuating the switch.

The alternative embodiment shown in FIG. 11 is essentially similar to that described in FIG. 1 and similar 7 parts will be assigned similar reference numerals in The first movable member 50" essentially comprises an elongated thin spring like member 96 having a terminal 96a (which is the common terminal 'of the switch atthe left end thereof as shown in FIG. 11, the other end thereof being angularly offset as shown in FIG. 11, the

other end thereof being angularly offset as shown at 98. The offset end 98 is formed into a pair of fingers 1ll0 102 (see FIG. 13), having V-shaped grooves 104 formed therein. A tongue 106 is struck out of the offset portion 98 and has a little nib 108 on the end thereof for purposes hereinafter appearing.

The operator means 78'- is essentially similar to that shown in FIG. 1 except that the lever member 79' is formed with a slot 110 which is adapted to cooperate with side notches in a force transmitting means The force transmitting means comprises a member 112 having opposed side notches 114116 which are adapted to cooperate With the sides of the slot in member 79' and are slightly larger than the thickness of the lever member. Central apertures 118 and 120' are formed in force transmitting member 80 to receive the biasing spring means 54', the nibs 108 on the first movable member being adapted to be inserted in the grooves 122-124 of the apertures 118-120 respectively. The lost motion connection between the operating lever 79' and the force transmitting member 88" is provided by the difierence in size of the slots H P-116 and the thickness of the member '79. As will be appreciated, the embodiment shown in FIG. 11 is easy to manufacture, but due to the relatively longer and spring like portion of movable member 50', switch 10 does not provide quite as much vibrational stability as does the assembly shown in FIG. 1.

FIGS. 14A, 14B, 15A, and 15B show various forces that are involved in the mechanism of the switch 10. FIGS. 14A and 14B show the stable positions of one contact assembly (the upper) in the two positions of the contact assembly. FIG. 14A shows the movable contact 76 up and against the upper. fixed contact 22b and FIG. 14B shows the movable contact 76 down and against its lower fixed contact 24b. FIG. 15A shows a transitory unstable position of the position of the switch assembly,

both the upper and lower contact assemblies being shown,

the condition being one that obtains when both contacts have been up (as shown in FIG. 15B), and the. top or upper switch contact assembly has just tripped and its movable contacthas moved down, whereas FIG. 15B shows the situation of the parts prior to tripping of the assembly with both movable contacts still in the up position.

F2 is one of the forces which upper lever 55 exerts against the insulated force transmitter 80. Force F2 is provided by spring 54, acting about fulcrum 46. It is apparent that the amount of this force dependson the geometry of the levers, as well as the strength of the spring. Because of the geometry, the force reduces gradually as the lever 50 is moved upward. The geometry prevents the force F2 from ever reaching 0. The couple about the pivot. point 46 consists of the product of the force F3 exerted against the spring notch 62 in member 50 by the contact blade 78 as provided by the spring 54 and the moment arm or distance that the line of action of this force F3 has-relative to pivot 46. This force F3 is at all times on the same side of the pivot 46, resulting in a constant biasing of the lever member 50 toward the center and into engagement with the insulated force transmitting member 80.

When the switch blade 70 overcenters with a snap action, the effect of force F2 is sharply reduced, since the vertical component of the reaction FRV of blade 70 against the fulcrum 62 reverses in direction instantly and detracts from the force F2 urging the lever 50 downward. The mechanism of the other (lower) switch pole has the mirror image relationship. It will be obvious that since the snap switch system for the lower contact assembly has the mirror image relationship, the first system of forces just discussed relative to force F2 when applied to the force F4 (the counterpart force of F2) is always opposite to force F2. Thus, forces F2 and F4 are in opposition to each other such that they largely cancel each other and they have only an auxiliary eliect on the motion of the force transmitting member 80, when the mechanism is for all practical purposes at or near the trip point or center position.

While other considerations cause some departurefirom this theoretical condition of exact opposition of forces of F2 and F4 as the mechanism is over traveled from the trip point to either of the stable positions shown in FIGS. 14A and 14B of the drawings, these departures from the theoretical conditions are not important to the functioning at the critical time, i.e., at the trip point or point of snapping over center. Stated another way, at or in the vicinity of the trip point of the switch, the biasing forces imparted by the springs 54 (force F3) about pivot points 40 and 46 to the levers 5t} effectively cancel each other so that they have no net effect on the motion of the force transmit-ting member 89 and the second system of forces about to be described becomes critical in the switch actuating mechanism.

The secondv system of forces in the assembly also relates to the force centered about the contact blade 70 and the notch 62 but is that aspect of the force not relating to the forces about pivot point 46. This second system relates to the reaction forces involved in the contacting blades 70 against the notches 6-2 and the fixed contacts. This reaction force FR may be resolved into its horizontal and vertical components FRH and FRV respectively. The critical feature in the actuating mechanism relates to force FRV, i.e., the vertical component since this force is related to the direction of force F2. The direction of the vertical component of the reaction force FRV against lever 50 is in the opposite direction of the contact force F1. that contact blade 70 supplies to the fixed terminal 22b and, as is obvious, will be equal in amount. -It will become obvious that the direction of the force FRV reverses every time the movable contact snaps from one fixed contact to the other fixed contact. In this regard see FIGS. 14 A and 14B. It is this instantaneous reversal of direction of the force FRV, which contributes to a desirable relationship, which causes a simultaneous action of both movable contact blades in the assembly shown. Since this vertical force reaction FRV is equal to the contact force F1 it follows that the force FRV will always approach 0 as the mechanism approaches the trip position.

While theoretically both movable contact mechanisms approach the trip point simultaneously, in practical construction, this does not in fact happen. While this is somewhat undesirable, as a practical matter it is impossible to eliminate. As a result, when one of the movable contact blades 70 approaches its trip point slightly ahead of the other, it will trip first. This condition is shown in FIG. 15A. As will be noted, the upper movable contact has moved from engagement with its upper fixed contact into engagement with its lower fixed contact, while the lower movable contact assembly is still in engagement with its upper fixed contact of its circuit. At this time, the vertical reaction force 'FRV of the lower movable contact assembly is still maintained in its original direction, but it has approached a very low value. When the first tripping pole (the upper movable contact assembly) has had its contact transfer, it will be found that the contact force F1 immediately assumes a reversed and high value and, in turn, the vertical reaction force FRV of that pole is reversed and is applied at a high value to the lever item 50. The result is that the total of forces in the direction of force E2 is reduced in value suddenly (on the assumption that the upper movable contact assembly has tripped first). Since F4 remains at its earlier value (due to the fact that its contact assembly has not yet tripped) the reversal of the force F1 will cause the force transmitting disk 80 to be biased in an upward direction. Due to the intentional lost motion between the force transmitting member 80 and the operating lever 88 it is possible for the force transmitting insulator mem ber 80 to move slightly upward. This movement is su-fiicient to bring the second pole past its trip point to effect essentially simultaneous operation of both poles. It will be obvious that the conditions shown in FIGS. 15A and 15B are transitory conditions which are unstable which result in a switch assembly where dead centering is impossible. I

The forces above discussed relative to switch 10. are similar in embodiment 10 except that the line of action of an equivalent to force F3 is always such that the members 50 are biased away from eachother rather than toward each other so that in a sense the reverse situation obtains in the forces.

Having thus described two embodiments of a skeleton type switch, it is to be understood that the illustrative forms were selected to facilitate the disclosure of the invention rather than to limit the number of forms which the invention may assume. Various modification-s, adaptations, and alterations may be applied to the specific forms shown to meet the requirements of practice, without .in any manner departing from the spirit or scope of the present invention, and all such modifications, adaptations, and alterations are contemplated that may come within the scope of the appended claims.

What is claimed as the invention is:

1. A switch comprising, first and second relatively thin elongated fiat metallic members insulatingly spaced in parallel alignment carrying fixed contact means on the ends thereof, movable contact means having a first and movable to a second position relative to said fixed contact means, thin elongated common terminal means insulatingly spaced from and in parallel alignment with said first and second members, said movable contact means comprising spring means, a first movable member, and a contact carrying member pivotally mounted on said first movable member, said spring means engaging said contact carrying member and said common terminal means to maintain the pivotal connection between said contact carrying member and said-first movable member and to provide a snap action to movement of said movable contact member, and operator means engageable with said first movable member to actuate said contact carrying member.

'2. A switch comprising a pair of first and second spaced fixed contact means, a pair of movable contact means having a first and movable to a second position relative to said fixed contact means, a pair of spaced common terminal means, each of said movable contact means comprising spring means, a first movable member and a contact carrying member pivotally mounted on said first movable member, each of said spring means engaging one of said contact carrying members and-one of said common terminal means to maintain the pivotal connection between one of said contact carrying members and one of said first movable members toprovide a snap action to movement of one of said movable contact members, and operator means engageable with each of said first movable members to simultaneously actuate both of said movable contact members.

3. A switch comprising, first and second relatively thin elongated fiat metallic members insulatingly spaced in parallel alignment carrying fixed contact means on the ends thereof, movable con-tact means having a first and movable to a second position relative to said fixed contact means, thin elongated common terminal means insulatingly spaced from and in parallel alignment with said first and second members, said common terminal means being relatively longer than said first and second members and formed with an angularly offset end portion, an aperture formed in said end portion, said movable contact means comprising spring means, a first movable member, and a contact carrying member formed with an aperture and pivotally mounted on said first movable member, said coil spring means engaging said aperture in said contact carrying member and said aperture in said offset portion of said common terminal means to maintain the pivotal connection between said contact carrying member andsaid first movable member and to provide. a snap action to' movement. of said movable contact. member, and operator means engageable with 'said first movable member to actuate said contact carrying member.

4. A switch comprising a stack of insulatingly spaced elongated members mounting a pair of first'and second spacedfixed contact means on the ends thereof, a pair of movable contact means each having a first andmovable to a seeondposition relative to a first and second fixed contact means, a pair of elongatedrcommon terminal means separately mounted at opposite ends of said stack, said common terminal means each being relatively longer than said elongated members and formed with angularly offset free end portions extending toward each other, said end portionsbeing formed with an aperture, each of said movable contact means comprising coil spring means, a firstmovable member, and a contact carrying member having an aperture and pivotally mounted on \said first 'movable member, each of said spring means engaging said aperture in one of said contact carrying members and said aperture in thefree end of said cornmon terminal means to maintain the pivotal connection between said contact carrying member and said first movablel member and to provide a snap. action to movement of said movable contactmember, and operatormeans engageable with each of said first movable members to simultaneously actuate both of said movable contact members.

5. The switch set forth in. claim 4 wherein said operator means comprises an elongated lever member relatively longer'than said common terminal means and a force transmitting member engaging each of said first movable members, there being a lost motion connection between said lever member and force transmitting member to provide simultaneous action of each of said contact carrying members on reversevmotion of said lever member.

aoaaeee 6. The switch set forth in claim 5 wherein said lever 7 member is formed with an'aperture for receipt of said coil spring means which passes therethrough, the pivotal connection of said first member and said contact carrying member being located intermediate the area defined by parallel planes defined by the ends of said coil spring means and generally transverse the major axis thereof. 8. The switch set forth inclaim 7 wherein said first movable member is formed with a first relatively straight portion havinga knife edge, a generally transverse portion having a central aperture defining spaced arms having a V-shaped groove formed therein and a curvilinear end portion, said knife edge being 'cooperable with one of said olfset free ends of said common terminal member for pivotal action thereon, said V-shaped grooves being adapted to receive said contact carrying member, and said curvilinear end portion being adapted to slidingly cooperate with said force transmitting member of said operator means. v

9. The switch set forth in claim 8 wherein said lever means is a thin flexible member formed with an aperture and said force transmitting memberis a cylindrical member having spaced enlargedhead portions at opposite ends thereof, said aperture in said flexible lever member receiving the body portion of said force transmitting member and being larger than the body portion and smaller than the head portions, the dimension between the spaced head portionsdefining the lost motion connection between the force transmitting member and the lever member.

10. The switch set forth in claim 8 wherein said first movable member is an elongated thin flexible member, aligned with said stack and disposed adjacent to a common terminal means in electrically conductive relationship thereto, said first movable member having an offset free end generally parallel to the oifset free end of said common terminal means, a tongue in said offset free end of said movable member extending generally parallel with the major plane of said common terminal means, an aperture in said iree end of said first movable member remaining after striking out said tongue portion to define a pair of spaced arms each formed with a V-shaped groove for pivotal connection with said movable contact carrying member, said tongue portion being cooperable with said force transmitting member of'said operator References Cited in the file of this patent UNITED STATES vPATENTS '7 2,728,826 Lauder Dec. 27, 1955 2,800,546 Reitler July 23, 1957 2,844,676 Barden et al July 22, 1958 2,905,781 Cherry -Sept. 22, 1959 FOREIGN PATENTS 1 206,527 Switzerland Nov. 16,1939 1,157,309

France Dec. 30, 1957 a tsi

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