US2810031A

US2810031A - Electric switch

Info

Publication number: US2810031A
Application number: US543423A
Authority: US
Inventors: Hellstrom Gosta Ludvig
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-11-26
Filing date: 1955-10-28
Publication date: 1957-10-15
Anticipated expiration: 1974-10-15

Description

Oct. 15V, 1957 G, L, HELLSTRQM `-27,810,031

` 'YELECTRIC'SWITCH Filed oct. 2a, 1955 5 sheets-sheet 1 GEK@ Oct. 15, 1957 G. L. HELLs'rRoM ELECTRIC 'SWITCH 5 Sheets-Sheet 2 Filedl Oct. 28, 1955 ,Av1 E MN, @P \\\\\&4 1 .Il a

Oct. 15, 1957 G. L. HELLsTRoM 2,810,031

ELECTRIC swITcH Filed Oct. 28, 1955 5 Sheets-Sheet 3A "wm/wmf Oct. l5, 1957 G. l.. HELLs'rRoM.r 2,810,031

" ELECTRIC -SWITCH Filed oct. 28, 1955 l 5 sheets-sheet 4 /d //9 /30 INVENTOR.

Oct. 15, 1957 G, L. HELLsTRoM 2,810,031

V ELECTRIC SWITCH Filed Oct. 28, 1955 5 Sheets-Sheet 5 IN V EN TOR.

United States Patent O ELECTRIC SWITCH Gosta Ludvig Hellstrom, Stockholm, Sweden Application October 28, 1955, Serial No. 543,423

Claims priority, application Sweden November 26, 1954 14 claims. (cl. zoo- 67) My invention relates to electric switches.

An object of my invention is to provide an improved switch of simplified construction which `requires relatively few parts and can be readily assembled.

Another object is to provide an improved switch which embodies a movable force transmitting member for positively shifting a coupling member with which a movable Contact is associated, and, when such positive shifting of the coupling member is terminated, completing the shifting of the coupling member by imparting thereto angular momentum with the aid of forces developed by an overcenter spring.

A further object is to provide an improved switch operated by a thrust member or push button in which the movable contact moves practically instantaneously from its circuit closing to its circuit opening position and vice versa irrespective of the rate at which the thrust member or push button is moved to its depressed position.

A still further object is to provide an improved switch which embodies a movable force transmitting member for shifting a coupling member with which the movable contact is associated, the force transmitting member having a pair of arms which serve to hold and retain an overcenter spring when it is deected to one side or the other of its line of action, the spring being held and retained in either of its stationary end positions by that `arm which becomes subject to a lateral bending force developed by its deflection while the other arm transmits from the spring to the coupling member a force acting in the same general direction as the lateraly bending force, which insures that the movable contact will always be at one or the other of its extreme end positions.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specication.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings, in which:

Fig. l is a perspective view of an electric switch embodying the invention; Fig. 2 is a top plan View, partly broken away and in section, of the switch shown in Fig. l; Fig. 3 is a vertical sectional View taken at line 3--3 of Fig. ll; Figs. 4 to 8 are perspective views of details or parts of the switch shown in Figs. 1, 2 and 3; Figs. 9 and l are plan views of the base and cover plate, respectively, of the switch shown in Figs. l, 2 and 3, the views being in directions from the joint between the parts when assembled; Figs. 11, l2 and 13 are similar vertical sectional views illustrating the switch of Figs. l, 2 and 3 in closed, intermediate and open positions, respectively; Figs. 14 to 17 are views diagrammatically illustrating the forces developed, by the spring of the switch when the parts thereof are in diierent positions;` Figs. 18, 19 and 20 are vertical views, partly in section, of an electric switch illustrating another embodiment of the invention, the figures being generally like Figs. l1, 12 and 13 and illus- 2,810,031 Patented Oct. 15, 1957 trating the switch in open, intermediate and closed positions, respectively; Fig. 2l is a vertical sectional view taken at line 21-21 of Fig. 18; Figs. 22 and 23 are vertical views, partly in section, of an electric switch illustrating a further embodiment of the invention, the ligures being generally like Figs. 1l and 12 and illustrating the switch in a closed and intermediate position, respectively; and Fig. 24 is a vertical sectional View taken at line 24-24 of Fig. 22.

AReferring to Figs. l and 2, I have shown my invention embodied in an electric switch having a base 10V and cover 11 forming an outer shell or housing 12, these parts being secured together by nuts 14 having hollow sleeve portions which are internally threaded to receive tightening screws 15. The cover 11 is formed with a central opening 16 through which a member 17 extends exteriorly of the housing 12, the member 17 serving as a thrust member for operating mechanism 18 to bring a movable contact 19 into and out of engagement with a pair of stationary contacts 20 adapted to be connected in an electrical circuit.

The stationary contacts 20, one of which is illustrated in Fig. 5, form parts of terminal members having apertured base portions 20a which receive threaded screws 20h. The base portion 20a of each terminal member, except that part against which the head of screw 20c overlies, bears against and is clamped between surface areas of the base 10 and cover 11 of the housing 12. A ridge formed in the base 10 is notched at 21, as illustrated in Figs. 2 and 9, to receive andhold edge portions of the contacts 2t). The cover 11 is notched at 22, as seen in Fig. l0, to receive the opposite edge portions of the contacts 20 and clamp the latter in place between the base 10 and cover 11 of the housing 12. When clamped in position in this manner, only the heads of the screws 20b and parts of the base portions V20a which,

the cover 11 being recessed at 23, as seen in Figs. 3 and Y 10, to receive the outer ends ofthe screws 20b.

The movable contact 19, which is illustrated in Fig. 8, is of U-shape and includes a pair of parallel arms which serve as contact fingers 19a and a connecting plate or base part 19b notched at 19e. The outer ends of the contact fingers 19a, which are enlarged and essentially circular, move into and out of intimate contact with the stationary contacts 20, as best seen in Figs. 3 and 11, the inwardly projecting ends of the contacts 20 being bent and flared outwardly with respect to one another.

As best seen in Fig. 4, the thrust member 17, which in the preferred embodiment serves as a push button for manually operating the switch, is in the form of `a hollow rectangular shaped sleeve having a closed end and side walls 17a and 17b. The sidewalls 17b are longer than the side walls 17a and formed with raised portions 17c` at their outer ends which serve as stops to limit the extent of outward movement of the member 17 through the opening in the cover 11, as will be evident whenv reference is made to Fig. 3. g

The mechanism 1liA interposed between the thrust member 17 and movable contactv 19- includes an elongated helical spring 24, a multi-armed force transmitting member 25 formed to hold and retain one end of the spring, and a bridge member 26 having a projection 26a arranged to` receive the opposite end of the spring, as best' shown in Fig; 7. The bridge member' 26 is formed with arms having recesses 26h at each' side of' the projection 26a in which diametrically opposite regions of the spring rest.

The force transmitting. member 25, which is in the form of a hollow vessel, is provided with notches or recesses 25a at the open end thereof in the opposing arms 25b and 25e, whichV are alternately adapted to` be engaged by' the ends 26e` of the bridge' arms when the' bridge member 26 moves between closed and open positions of the switch, as will be explained presently.

The mechanism 1S, which may be referred to as a spring compression and bow unit, is pivoted at its opposing ends to enable the force transmitting member 25, overcenter spring 24 and bridge member 215 to swing back and forth between the positions illustrated in Figs. 11 and 13, the overcenter spring 24 in these positions being bowed in opposite directions from the line of action or straight line position illustrated in Fig. 12. As seen in Figs. ll, 12 and 13, the thrust member 17 is formed with a ridge or knife-edge 17d at the inside thereof which is adapted to receive a notch or groove 25d formed at the closed end of the hollow force transmitting member 25.

As shown in Fig. 9, at the bottom of the base 11) is formed a U-shape ridge 27 and a pair of L-shape ridges 2S, the ridges being arranged to form a pair of elongated grooves 29 therebetween. The arms of the U-shape ridge 27 at their ends are beveled at 27a, as best shown in Figs. 9 and 1l. The sides of the shorter arms of the L-shape ridges 28 are beveled at 28a as best shown in Figs. 9 and l2. The gap between the beveled edges 27a and 23a, in a direction transverse to the parallel arms of the U-shape ridge 27, forms a groove 29 which is adapted to receive the cross plate or base part 19e of the movable contact 19. The movable contact 19 moves through an acute angle in the groove 29, the axis about which such angular movement is effected being about a line passing through the extreme bottom portion 19d of the base part 191: of the movable contact 19, as best seen in Fig. 3.

The bridge member 26 is formed with a slot 26d of X- shape, as best shown in Fig. 7. The notchedpart 19C of the movable contact 19 forms a saddle which receives the recessed part 26d of the bridge member 26. Since the slots 26d is of X-shape, the bridge member 26 can move angularly with respect to the base part 1915 of the movable contact 19. The angular movement of the bridge member 26 with respect to the Contact member 19 is limited, such relative angular movement terminating when a long side of the X-shape slot 26d, with angular movement being imparted to the bridge member 26, engages and contacts a side or face of the base part 19h of the movable contact 19. It will now be understood that the bridge member 26 moves angularly about an axis 30, indicated by a dotted line in Fig. 8 which passes through the bottom of the notch 19C of the movable contact member 19. Also, the axis 30 about which the bridge member 26 is angularly movable is nearer to the recessed regions 26b holding an end of the spring 24 than the axis at 19d about which the movable contact 19 is angularly movable.

The base and cover 11 of the housing 12, thrust member 17 and force transmitting member 25 are made of any suitable insulating material. The terminal members, of which the stationary contacts form a part, and the movable contact 19 form electric conducting parts which are mounted on the insulating parts in the manner described above. The spring 24 and bridge member 26 desirably are formed of metal.

In order to simplify the description, the force transmitting member will be referred to hereinafter in the specification and also in the claims as a force member, and the bridge member 26, which is movable between the two positions illustrated in Figs. 11 and 13, respectively, will be referred to as a part of a coupling member with which the movable contact 19 is operatively associated.

The parts of the switch described above are shown in one stationary position in Figv 11. In such position, the stops 17e of the thrust member 17 are functioning to limit outward movement thereof through the opening in the cover 11 and the spring 24 is under compression and bowed or deflected against the left-hand arm or side 25h of the force member 25. Under these conditions an upward force P1 is exerted by the spring 24 against the force member 25 at a region of the latter which is to the left of the knife edge 17d. A downward force P2 is also exerted by the spring 24 against the bridge member 26 and movable contact 19 at a region which is to the left of the positions at which these parts are supported.

'Ihe upward force P1 is transmitted through the righthaud side or arm 25C of the force member 25 and the right-hand arm of the bridge member 26 to the movable Contact 19, such force being designated P3 in Fig. ll. The lower end of the spring 24 bears against and comes in intimate contact with the bridge member 26 at a single region 31, thereby causing the spring to be bent or bowed toward the left in Fig. 11. The left-hand arm or side 25h of the force member 25 serves to support and maintain the spring 24 in a definite position with no opportunity for the spring to be distorted out of shape. Such deflection of the spring 24 develops a lateral upward force P4 which, together with the upward force P1, cooperates to exert a force to maintain the movable contact 19 in the left-hand position shown in Fig. 11 at the same time that the upward and lateral forces P1 and P3, respectively, are effective to maintain the recess 25a in the right-hand arm 2SC of the force member 25 in intimate contact with f and bearing against the right-hand arm of the bridge member 26.

The thrust member 17 is depressed when it is desired to operate the switch. When this occurs, the force member 25 in Fig. 11 is moved against the right-hand arm of the bridge member 26, thereby forcing the bridge member to be angularly moved in a clockwise direction and at the same time imparting angular movement to the force member 25 toward the right about the knife edge or pivot point 17d.

When movement is imparted to the force member 25 toward the right from the position shown in Fig. l1, the left-hand arm or side ZSb thereof bears against the spring 24 to impart movement thereto, thereby causing the spring to be moved toward its straight line position to assume a more straightened position. Such straightening of the spring 24 is also effected by the bridge member 26 which, when being angularly moved in a clockwise direction in Fig. 11, raises or lifts the lower end of the spring 24 at the region 24a of the extreme bottom turn thereof.

When clockwise angular movement is initially imparted to the bridge member 26 in Fig. 11, the contact member 19 remains stationary. Movement is imparted to the contact member 19 only after the bridge member 26 has moved through an acute angle equals to the angle measured between the conecting base part 19e of the contact member and a long side 26e of the X-shape slot 26d of the bridge member 26, as indicated in Fig. ll.

Since the bridge member 26 moves angularly about the axis 39, as indicated in Fig. 8, it will be apparent that the depth of the U-shape notch 19t: at the closed end of the movable Contact 19 determines the position of this axis. Since the contact member 19 in turn is angularly movable about the axis 19d, as indicated in Figs. 3 and 11, it will be understood that the axis 3i) about which the bridge member 26 moves is nearer than the axis 19d of the contact member 19 to the region or place 2612 at which the spring 24 acts on these parts. By virtue of this relationship of the contact member 19 and the bridge member 26, the force P2 developed by the spring 24 in turn produces forces P5 and Ps which effectively hold the contact member 19 in the extreme left-hand position shown in Fig. ll when clockwise angular movement is initially imparted to the bridge member 26. It is only after the bridge member 26 has moved through the angle a in Fig. 1l, and the long side 26e of the X-shape slot 26a bears against a face of the bottom connecting part 19in of the movable contact19, that movement is imparted to the latter.

Fig. 12 illustrates the relative positions of the parts when the thrust member 17 has been depressed sui'iciently to move the overcenter spring 24 to its line of action and the forces developed by the spring and acting on the bridge member 26 and movable contact 19 are such that these parts are in a labile neutral position. Upon oontinued inward movement of the thrust member 17, the parts are positively moved toward the right in Fig. 12, the force developed by the spring 24 against the bridge member 26 all the while producing a torque in a clockwise direction on the latter which is of increasing magnitude. During such movement of the spring 24 from the straight line position in Fig. l2, the spring assumes a bowed or bent position opposite from that illustrated in Fig. ll.

The bent spring 24 now acts against the right-hand arm or side 2SC of the force member 25, and a lateral force P7 is developed which also acts on such right-hand arm 25e. As the force member 2S is moving toward the right in Fig. 13 and the lateral force P7 becomes increasingly greater, the recessed portion 25a in the righthand arm 25C eventually becomes ineffective to hold the extreme end 26e of the right-hand arm of the bridge member 26 and the force member 25 becomes disengaged from the right-hand arm of the bridge member and moves angularly toward the right to the position shown in Fig. 13.

As the spring 24 moves from the straight line position in Fig. l2 to the deected position shown in Fig. 13, it `develops an upward force Ps at the right-hand side of the knife edge 17d which also imparts angular movement to the force member 2S toward the right. The spring 24 also develops a downward force P10, indicated in Fig. 13, which imparts angular movement to the bridge member 26 in a clockwise direction. The doublearmed force member 25 and the bridge member k26 are supported at such a distance from` one another and are developed in such a manner that the lateral and upward forces P7 and Pa, respectively, which are developed by the spring 24, are effectively transmitted through the left-hand arm or side 25b of the force member to the left-hand arm of the bridge member 25 both by impact and by a force P9, thereby imparting an angular momentum to the bridge member 26 in a clockwise direction which is in addition to the movement imparted thereto by the downward force P10.

ln View of the foregoing, it will now be understood that as the parts or" the switch move from the position shown in Fig. ll past the neutral position shown in Fig.

l2, the notch or recess 25a in the right-hand arm 25o` of the force member is in engagement with the eXtreme end 26C of the right arm of the bridge member 26. While these parts of force member 25 and bridge member 26 are in engagement, the bridge member 26 and movable contact 19 supported thereon are being angularly moved by a force transmitted from the right-hand arm 2SC of the force member to the right arm of the bridge member, such positive shifting of the bridge member and contact arm being effected independently of the spring 2dy while the latter is being moved to and past its labile neutral position.

When the overcenter spring 24 moves past its line of action or labile neutral position, the forces P7, Pa and Pio developed by the spring become of increasingly greater magnitude. When the switch parts are in a certain position between the neutral position seen'in Fig. l2 and the position shown in Fig. 13, the positive shifting of the bridge member 26 by the force member 25 terminates due to the right arm of the bridge member 26 becoming disengaged from the right-hand arm 25e of the force member. When this certain position of the switch parts is reached, angular movement is imparted to the bridge member 26 and movable contact 19 solely by the forces developed by the spring 24, as explained above. The angular momentum imparted to the bridge member 26 by the forces P7, Ps, P9 and Pio,

of the force member 25 against the left arm of the bridge member 26, is of such magnitude that the angular movement of the bridge member 26 is accelerated in the act of moving the contact fingers 19a of contact 19 out of engagement with the stationary contacts 2t).

The aforementioned certain position of the switch parts, when the positive shifting of the bridge member 26 by the force member 25 is terminated and such shifting is completed by the forces developed by the spring 24, is determined by the forces acting on the movable contact 19. These forces include the braking forces, contact pressure and other frictional forces acting on the movable contact 19.

An important advantage realized from a switch like that being described and illustrated and embodying the principles of the invention is that when tolerance limits are exceeded which would jeopardize dependable operation of other switch constructions, the fact that such tolerance limits are exceeded in switches constructed according to the invention is not so material. This is so because the positive shifting of the bridge member 26 by the force member 25 continues until the increasingly greater angular momentum given to the bridge member by the downward force P10, which is developed by the spring 24, imparts to the movable contact 19 an angular velocity appreciably greater than the velocity at which the thrust member 17 is depressed. This increasingly greater angular momentum, which acts on the movable Contact with a relatively short lever arm, receives a substantial boost by the impact of the force member 25 on the bridge member 26 as well as by the force transmitted to the latter from the force member, so that the angular shifting of the bridge member 26 and movable contact 19 thereon is assured.

When the thrust member i7 in Fig. 13 is released and allowed to move exteriorly of the shell orV housing 12 by the biasing action of the spring Z4, the force developed in the left-hand arm 25b of the force member continues to exert a pressure -against the left arm of the bridge member 26. When the thrust member 17 in Fig. 13 reaches its outermost position, as indicatedby the dotted line, the extreme outer endl of the left-hand arm 25h of the force member rides over the eXtreme outer end 26C of the left arm of the bridge member. When this occurs, the force member 25 swings to the right and the extreme outer end 26e of the left arm of the bridge member enters the notch or recess 25a in the left-hand arm 25b of the force member, whereupon the parts of the switch are in a stationary position which is a mirror image of Fig. 11. In view of the foregoing, it will be evident that the gap or distance between the recesses 25a in the arms ZSb and 25s of the force member is greater than the gap be tween the extreme ends 26e of the bridge member 26, as best seen in Fig. 12.

When the thrust member is again depressed and subsequently released, the parts of the switch move back to the position shown in Fig. ll and the contact fingers 19a of the movable contact i9 are in engagement with the stationary contacts 20. In such return movement of the movable contact 19, the forces P1, P2 and P4 developed by the spring 24 act in three directions and cooperate with another to effect movement of the movable contact 19. The spring 24, which is relatively Weak, enables the switch to be operated easily yand silently; and, since the forces developed by the spring while under compression are transmitted through relatively short lever arms, it is possible to provide a switch like that described and illustrated which is of small size and yet produces the necessary force to move the contact lingers 19a into engagement with the stationary contacts 20. By way of example and without limitation, a switch like that described and illustrated has been constructed for operating household vacuum cleaners of standard size in which the length, width coupled with the impact force of the left-hand arm 251: and depth of the outer Shell are 1%, wie" and its,

respectively. The overall height of the switch, when the Vthrust member 17 is not depressed, is 13716.

It will be seen that the force member 25, which is formed of insulating material, provides a partition between the stationary contacts 20 when the movable contact 19 moves into and out of engagement therewith, as best seen in Fig. 2. The two relatively thin walls 25]c connecting the arms 25d and 25e form a space in which the spring 24 is positioned. The gap between the side walls ZSf of the force member can be made relatively large to provide a suitable shielding action between the stationary contacts 2i) at the instant the movable contact 19 becomes disengaged therefrom. In this way, the distance between the stationary contacts 20 can be made relatively small, especially in switches of small size having a narrow width, without any danger of arcing between them when the movable contact 19 is disengaged therefrom.

In Figs. 14 to 17 I have schematically illustrated the manner in which the forces are developed in the spring 24 and transmitted from the latter and the force member 25 to the bridge member 26 upon which the movable contact 19 is carried. 1n Figs. 14 to 17 the left and right-hand arms of the force member 25 are designated 25b and 25C and the recesses at the outer ends thereof are indicated at 25a. The force member 25 is formed with a pointed end 25e which is angularly movable in a groove 17e formed at the underside of the thrust member 17. In Figs. 14 to 17 the bridge Z6 is formed with arms having extreme end portions 26C. In Figs. 14 and 15 the projection 26a on the bridge member 2.6 is diagrammatically indicated, while in Figs. 16 and 17 the recesses 26h at each side of the projection 26a are diagrammatically indicated.

In the diagrammatic views seen in Figs. 14 to 17 the movable contact part 1917 and bridge member 26 move as a single unit. Hence, the relative angular movement effected between the movable contact 19 and bridge member 26, which is obtained in the manner described above and apparent in Figs. 11, 12 and 13, is not illustrated in the diagrammatic views of Figs. 14 to 17 in order to make these views as simple as possible.

In Figs. 14 to 17 the bridge member 26 is diagrammatically supported on the movable contact member 19, only the bottom part 19h of which is shown. The part 1911 is angularly movable in a groove 29 formed in a base 11i which are diagrammatic representations of the corresponding parts seen best in Figs. 9 and 12.

Figs. 14 and 15 illustrate the development of the spring forces when the overcenter spring 24 is at the left and right-hand sides of the line of action or neutral labile position indicated at 24a. Fig. 14 illustrates the upward force P1 developed by the spring 24 at the left of the line of action 24a and the manner in which this force is transmitted through the right-hand arm 25e of the force member 2S and applied by the latter to the right arm of the bridge member 26, as indicated by the force P3. Fig. 15 illustrates the upward force Pa developed by the spring 24 at the right of the line of action 24a and the manner in which this force is transmitted through the left-hand arm 2515 of the force member 25 and applied by the latter to the left arm of the bridge member 26, as indicated by the force P9.

Figs. 16 and 17 illustrate the way in which the bending and deecting of the spring 24 is promoted and the lateral forces developed by the latter which cooperate with the upward and downward forces developed by the spring. In Fig. 16 the eXtreme lower turn of the spring 24 engages the bridge member 26 at the single point 31 which promotes bending of the spring at the left of the line of action 24a, such bending of the spring developing the lateral force P4 which cooperates with the upward spring force P1 to increase the magnitude of the force Ps. In Fig. 17 the extreme lower turn of the spring 24 engages the bridge member 26 at the single point 31a,

which is directly opposite the point 31 in Fig. 16, thereby promoting bending of the spring at the right of the line of action 24a and developing the lateral force P7 which cooperates with the upward spring force Pa to increase themagnitude of the force P9.

It has been explained above that, when the positive shifting of the bridge member 26 by the force member 25 is terminated, the shifting of the bridge member is completed by the angular momentum imparted to the latter by forces developed by the spring 24. These forces developed by the spring 24, which are transmitted directly to the bridge member and through the force member 25, become of increasingly greater magnitude as the bending of the spring becomes more pronounced, thereby accelerating the angular movement of the bridge member 26. Even when the thrust member 17 returns from the depressed position to the raised dotted line position in Fig. 13, the left-hand arm 25h of the force member 25 continues to move angularly from the position shown in Fig. 13 to la position which is the mirror image of the right-hand arm 25C of the force member 25 in Fig. 11. In this way, the notch 25a in the left-hand arm 25h of the force member 25 eventually receives and engages the extreme end 26C of the left arm of the bridge member, so that the force member 25 will again be effective to positively shift the bridge member 26 when the thrust member 17 is depressed to move the movable contact 19 to the left into engagement with the stationary contacts 211. Hence, even as the thrust member 17 moves exteriorly of the shell 12 after being depressed, such outward movement enables the spring 24 to be bent to a greater degree which in turn develops a lateral force of greater magnitude and like the force P4 in Fig. 11, for example, to insure a good contact pressure between the contact fingers 19a and stationary contacts 2t) even when the parts are in a position of rest. The bridge member 26 is embodied in the switch in such a manner that it will move freely and enable the movable contact 19 to move practically instantaneously from its circuit closing position to its circuit opening position and vice versa irrespective of the rate at which the thrust member 17 is moved to its depressed position. This is characteristic of the switch because the spring 24 is compressed and it moves beyond the line of action or labile neutral position before the movable contact 19 becomes disengaged from the stationary contacts 20. It is only after the spring passes through and beyond the labile neutral position that the forces developed by the spring begin to act in such directions that the separation of the contacts is effected.

In view of the foregoing, it will now be understood that an improved switch has been provided of simplified construction which requires relatively few parts and can be readily assembled. The parts formed of insulating material can be formed with simple tools and do not require so-called undercutting The switch illustrated in Figs. 1 to 13 is extremely dependable in operation and highly resistant to wear, the relationship of the parts being such that errors in tolerance do not adversely affect switch operation and its durability.

Figs. 18 to 21 illustrate another embodiment of the invention in which parts similar to those shown in the first described embodiment are designated by the same reference numerals to which one hundred has been added. In Figs. 18 to 21 the housing or shell includes a base and cover 111 which are removably secured together in any suitable manner, as in the embodiment of Figs. 1 to 13, for example. The cover 111 is formed with a central opening 116 through which a thrust member 117 extends exteriorly of the housing, the thrust member having a projection 117C to limit outward movement thereof. The member 117 serves as la push button for operating mechanism 118 to bring a U-shape and out of engagement with a pair of stationary con- 9 facts 120 which form part of terminal members 120:1 adapted to be connected in an electrical circuit.

The mechanism 118 interposed between the thrust member 117 and movable contact 119 includes an elongated helical spring 124, a multi-armed force member 125 arranged to hold land retain one end of the spring, and a bridge member 126 having a projection 126:1 arranged to receive the opposite end of the spring. The force member 2.5, which is in the form of a hollow vessel, is provided with notches or recesses 12Sa at the open end thereof in the opposing arms 12517 and 125e, which are alternately ladapted to be engaged by the ends 126e of the bridge arms when the bridge member 126 moves between closed and open positions of the switch, as in the first described embodiment.

As seen in Figs. 18, 19 and 20, the force member 125 is formed with a pointed end 125e which is angularly movable in a groove 117e formed at the underside of the thrust member 117. The base 110 is formed with a groove 129 which is Iadapted to receive the` cross connection or base part 119b of the movable contact 119. The bridge member 126 is formed with a slot 126d of inverted V-shape which tits in a notched part 119e of the closed end 11% of the U-shape movable contact 119, as best shown in Figs. 19 and 20. As in the first described embodiment, the opposing edges of slot 126d diverge from one another so that the bridge member 126 can move angularly with respect to the base part 119b of the movable contact 119.

The bridge member 126 moves angularly about an axis 131i, indicated by a dotted line in Fig. 21, which passes through the bottom of the notch 119e of the movable contact member119. The axis 130 about which the bridge member 126 is angularly movable is nearer to the bottom end of the spring 124 than the axis at 119d about which the movable contact 119 is angularly movable. When angular movement is initially imparted to the bridge member 126 from a position of rest, the contact member 119 remains stationary. Movement is imparted to the contact member 119 only after the bridge member 126 has moved through an acute angle a equal to the angle measured between the connecting base part 119b of the contact member 119 and an edge of the V- shape slot 126:1 of the bridge member 126, as indicated in Fig. 18.

The operation of the switch illustrated in Figs. 18 to 2l is essentially the same as that of the switch shown in Figs. 1 to 13 and described above and will not needlessly be repeated here. The different forces producedV in the operation of the modification of the invention shown in Figs. 18 to 21 are like those seen in Figs. 11 and 13 and are designated by the same reference letters, it being further understood that the force diagrams of Figs. 14 to 17 are applicable equally well to the embodiment of Figs. 18 to 21 as to the tirst described embodiment of Figs. l to 13.

1n Figs. 22, 23 and 24 I have shown another embodiment in which parts similar to those shown in the embodiments described above are designated by the same reference numerals to which two hundred (200) has been added. Figs. 22, 23 and 24 illustrate a shell or housing 212 of a switch having a base 210 and a cover 211 formed with an opening 216 through which extends a

thrust member

2,17 having projections 217e` to limit outward movement thereof.

The underside of the thrust member 217 is formed with a recess 217e to receive the pointed end 225e of a force member 225 which is in the form of a bow and provided with arms 225i: and 225C having notched or recessed ends 225a. The notches or recesses 22511 are adapted to a1- ternately engage the extreme ends 226e of the arms of a bridge member 226 which is pivoted at 226g in an opening 235 formed at the bottom part of a wall member 236 projecting inwardly of the housing 212 from the base 210.

The wall member 236 serves as a pivot point for a movable contact 219 comprising a pair of yspaced apart contact tingers 219e which are parallel to one another and upon which a slide member 237 is movable length wiseof and between the contact fingers. The slide member 237 is of U-shape and receives the lower end of the spring 224. The bridge member 226 is formed with pusher arms 226i which are of U-shape and perpendicular to the main bridge arms and serve to limit endwise movement of the slide member 237 on the movable contact member 219.

ln the position illustrated in Fig. 22, in which the movable contact 219 is in engagement with the stationary contacts 220, the forces developed by the spring 224 and right-hand arm 225C of the force member 225 are simil-ar to the forces developed and identied in Fig. 11 of the irst described embodiment. In Fig. 22 the downward spring force, similar to the force P2 in Fig. 13, is acting against the left arm of the bridge member 226 through the slide member 237, left-hand end of the movable contact 219 and left-hand pusher arm 226f of the bridge member 226.

As the force member 225 positively shifts the bridge member 226 from the position shown in Fig. 22 to the position shown in Fig. 23, the spring 224 moves toward its labile neutral position, the left-hand pusher arm 226]c vof the bridge member positively moving the slide member 237 during this period of movement of the switch parts. When the spring 224 moves through and beyond its labile neutral position, the forces developed by the spring 224 and force member 225 are essentially the same as those developed by the corresponding parts in the rst described embodiment and identified in Fig. 13. After the spring 224 moves through and beyond its labile neutral position,

the slide member 237 moves to a position at the right- Y hand end of the movable contact 219. When the thrust member 217 moves outwardly of the shell or housing of the switch, the parts of the embodiment being described assume a position which is a mirror image of the relative position of the parts shown in Fig. 22. A

In Figs. 22 to 24 the movable contact 219 pivots about a region which is nearer to the lower end of the spring 224 than the region about which the bridge member 226 pivots. It will be observed that in the embodiment of Figs. 22 to 24 no relative angular movement is effected l between the movable contact 21.9 and the bridge member 226. In other respects, however, the operation of the embodiment of Figs. 22 to 24 is essentially the same as that of the embodiments illustrated and described above.

Although I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. For example, the thrust member and for-ce member may be arranged in such a manner that the force member is angularly movable about two spaced apart pivot regions which are a substantial distance from one another and symmetrically disposed with respect to the thrust member, an arrangement which may be desirable under certain conditions, in order to make certain that the shifting of the bridge member to its end position is completed before the last increment of angular movement of the force member is effected from the position shown in Fig. 13, for example, to a position which is a mirror image of the switch parts illustrated in Fig. 11. I, therefore, aim in the following claims to cover all such modications and changes as fall within the true spirit and scope of the invention.

What is claimed is:

l. An electric switch comprising a movable contact, a coupling member movable between two positions, said coupling member including a bridge having two arms and with which said movable contact is operatively associated, a movable force member having a pair of arms, one of the arms of said force member having a part adapted to Y 11 Y Y be engaged by a part of one arm of said bridge and the other arm of said force member having a part adapted to be engaged by a part of the other arm of said bridge, a thrust member movable between first and second positions, means comprising said force member for shifting said coupling member back and forth between its two positions responsive to repeated movement of said thrust member from its first to its second position, the parts of the arms of said force member alternatively engaging the parts of the arms of said bridge upon successive movements of said thrust member from its iirst to its second position, and the gap or distance between the parts of the arms of said force member being greater than the gap or distance between the parts of the arms of said bridge adapted to be engaged alternatively by the parts of the arms of said force member.

2. An electric switch comprising a movable contact, a coupling member movable between two positions, said coupling member including a bridge having two arms and with which said movable contact is Voperatively associated, a movable force member having a pair of arms, one of the arms of said force member having a part adapted to be engaged by a part of one arm of said bridge and the other arm of said force member having a part adapted to be engaged by a part of the other arm of said bridge, a thrust member movable between irst and second positions, means comprising said force meinber for shifting said coupling member back and forth between its two positions responsive to repeated movement of said thrust member from its first to its second position, the parts of the arms of said force member alternatively engaging the parts of the arms of said bridge upon successive movements of said thrust member from its first to its second position, each arm of said force member, after said bridge has been shifted in one direction by the other arm of said force member responsive to movement of said thrust member from its first to its second position, being movable in the same one direction toward said bridge to bring the part associated therewith into engagement with the part of the arm of said bridge with which it is adapted to cooperate responsive to return movement of said thrust member from its second position toward its lirst position, so that said force member will be operable to shift said coupling member in the opposite direction from said one direction responsive to the next succeeding movement of said thrust member from its first to its second position.

3. An electric switch comprising stationary and movable contacts, a coupling member angulaily movable between two positions and with which said movable Contact is operatively associated, a force member movable between two position-s,-said force member having a pair of arms, a thrust member movable between first and second positions, means comprising said force member for shifting said coupling member back and forth between its two positions responsiveV to repeated movement of said thrust member from its first to its second position, said lastmentioncd means including an overcenter spring between said force and coupling members for biasing said thrust member to its first position and alternatively retaining said force and coupling members at one and the other of their two positions at opposite sides of the line of action of the spring, means including said force member for imparting angular momentum to said coupling member responsive to a torce developed by said spring when the latter moves through its line of action from one to the other side thereof, such angular momentum imparted to said coupling member when said spring moves from one to the other side of its line of action being effective to move said movable contact into engagement with said stationary contact, each arm of said force member, when the latter is in one or the other of its two positions, serving to supportsaid spring while being deected from its line of action, and said movable contact being urged to move as far as possible, while said spring is deilected from its line of action toward one arm of said force member, responsive to forceY transmitted from said spring through the other arm of said force member.

4. An electric switch comprising a movable Contact, a coupling member movable between two positions and with which said movable contact is operatively associated, a movable force member having a pair of arms, a thrust member movable between first and second positions, means comprising said force member for shifting said coupling member back and forth between its two positions responsive to repeated movement of said thrust member from its lirst to its second position, said last-mentioned means including a spring retained between said force member and coupling member which biases said thrust member tcits first position, said coupling member including a bridge which is movable therewith and imparts movement to said contact, said bridge being eiective to imp-art movement to said Contact only after movement has been imparted thereto for an interval of time responsive to shifting of said coupling member from a position of rest by said force member.

5. A switch as set forth in claim 4 in which said spring acts against a place of said coupling member, said movable contact comprising a member angularly movable about a rst axis and said bridge being angularly movable about a second axis which is nearer to the place at which said spring acts than said first axis, said contact member, during the interval of time said bridge is ineffective to impart movement thereto, being retained in a position of rest responsive to the action of said spring on the part of said Contact member between said irs't and second axes.

6. A switch as set forth in claim 4 in which said contact comprises a member formed with a notch, and said bridge is formed with a slot in which the opposing edges diverge from one another, the notched portion of said contact member receiving and holding the slotted part of said bridge.

7. A switch as set forth in claim 4 including structure providing a support, said contact comprising a member which is angularly movable about the support and said ridge member including a part resting on and angularly movable about a region of said contact member, said region, when the switch is positioned with said bridge member directly beneath said force member, being at a level at least as high as the support for said contact member.

8. A switch as set forth in claim 4 in which said contact comprises a member which is angularly movable, said member including a part extending lengthwise of the axis about which it moves and two contact fingers at opposite ends of said part which are formed integral therewith, said contact fingers projecting radially from said axis at the same side thereof as said part.

9. A switch as set forth in claim i in which said force member is pivotally movable on said thrust member, one of said members havin T a grooved part and the other of said members having a part fitting into and angularly movable in such grooved part.

10. A switch as set forth in claim l which includes a wall part having an opening, said thrust member extending through such opening and serving as a push button, such push button being of annular form having a closed outer end and four walls extending inwardly therefrom through the opening, two of said walls being shorter than the other two walls which are disposed in planes essentially parallel to the plane of movement of the arms of said force member.

ll. An electric switch comprising a movable contact, a coupling member angularly movable between two position-s and with which saidpmovable contact is operatively associated, said coupling member including a bridge, a movable force member having a pair of arms, a thrust member movable between first and second positions, means comprising said force member for shifting said coupling member back and forth between its two positions responsive to repeated movement of said thrust member from its rst to its second position, said last-mentioned means including spring means which biases said thrust member to its rst position and constitutes the only means for retaining said thrust member, force member, bridge and contact in position with respect to one another when the parts just mentioned are at rest or movement is imparted thereto.

12. A switch as set forth in claim l1 which includes a two-part shell or housing and means for removably connecting said parts, said spring means comprising a single elongated coil spring of helical form which, in addition to said removable connecting means for said twopart shell, constitutes the only means for retaining said thrust member, force member, bridge and contact in position with respect to one another in said shell when the parts just mentioned are at rest orpmovement is imparted thereto.

13. An electric switch comprising a pair of stationary contacts and a movable contact adapted to be brought into and out of engagement therewith, a coupling member movable between two positions and with which said movable contact is operatively associated, a movable force member, a thrust member movable between rst and second positions, means comprising said force member for shifting said coupling member back and forth between its two positions responsive to repeated movement of said thrust member from its first to its second position, said force member being formed of insulating material and being disposed between said stationary contacts to provide an insulating partition therebetween, especially when said movable contact becomes disengaged from said stationary contacts, to reduce the likelihood of a disruptive discharge therebetween.

14. A switch as set forth in claim 12 which comprises stationary contacts cooperating with said movable contact, said stationary contacts being clamped in position between the two parts of said shell and having terminal portions disposed exteriorly of said shell, and fastening means for said terminal portions adapted to make electrical connections thereto.

References Cited in the le of this patent UNITED STATES PATENTS 1,997,209 Douglas Apr. 9, 1935 2,255,115 Helle Sept. 9, 1941 2,295,484 Krieger Sept. 8, 1942 2,383,546 Hallander Aug. 28, 1945 2,529,970 Schmid Nov. 14, 1950