US2255115A - Switch - Google Patents

Description

sept. 9, 1941.

W. W. HELLE swITcx-r Filed May 9, 1938 3 Sheets-Sheet 1 Sept. 9, 1941. w. w. HELLE SWITCH Filed May 9, 193s A 3 Sheets-Sheet 2 rllll A Sept. 9, 1941.

w. w. HELLE 2,255,115

SWITCH.,

Filed May 9, 1958 s sheets-sheet :s

Patented Sept. 9, 1941 UNITED sTATEsVPATENT oFF-ical SWITCH Warren W. Helle, Hinsdale, Ill.

Application May 9, 1938, Serial No. 206,701

7 Claims.

quickly from the closed position to the open position and numerous devices have been provided for accomplishing this result. It has also been recognized that a fairly rm contact pressure between the closed contacts is desirable, Aand most of the switch mechanisms have provided such firm pressure while the switch is at rest. However, in switches in which the operating mechanism supplies the contact pressure (as distinguished from knife switches, in which the pressure is supplied by the jaws which grip the blades) there has been a common fault which may be described as a gradual decrease of pressure during movement of the actuating mechanism before it has moved far enough to operate the switch and break a circuit, for instance.

Such switches have generally connected the actuating lever to the movable switch member through some sort of a spring for the purpose of providing a snap movement. With the movable switch member in one position and the spring pressing it firmly in that position, the actuating lever or handle would be moved, and as it moved it would shift the spring until the spring had passed the dead-center position and was pressing the movable member in the opposite direction, at which time this member would snap to its alternative position. It will be observed that in all such switches the spring must inevitably pass through a dead-center position in which it is not supplying any contact pressure and as it approaches this dead-center position the contact pressure which it exerts must be diminishing. Of course, if the actuating lever is moved quickly the duration of the diminishing pressure is rather short and may be harmless. On the other hand, in the case of some automatic devices, such as a valve controlling switch operated by a float for keeping the water at a given level in a tank, the movement of the actuating lever will be very gradual with the result that there may be a substantial length of time during which the contact pressure at the closed contacts is too low. 'I'he result of such low contact pressure may be very harmful to the switch because it results in high Contact resistance or possibly even a slight separation of the contacts-resulting in arcing and burning of the contacts.

An object of the present invention therefore is to provide a switch in which the actuating mechanism maintains an adequate contact pressure until the instant that it snaps the movable switch member to separate the contacts so that even with a slow movement of the operating handle there will be no appreciable time during which thercontact pressure is inadequate. In general, it may be stated that this is accomplished according to the present invention by providing a spring actuating arrangement in which the actuating spring snaps from the position urging the movable member in one direction to the position urging the movable member in the other direction so that, until the yspring snaps, the contact pressure will be firm and then instantaneously the fun pressure wiu be shifted to the opposite direction. In the preferred illustrated forms of the invention the predominant force of the spring as applied to the movable member is a compressional force and this full compressional force is exerted in one direction until the spring is twisted by the actuating lever in such a way that, although the twisting movement may be gradual initially, the compressional force remains and is therefore shifted instantaneously as the spring eventually snaps to its alternative position. In short, the mechanism applies a relatively constant pressure to the movable member and shifts the direction of this force instantaneously.

Another object of the invention is to provide a more durable and uniformly acting spring for switches of the general type in which a spring is utilized to flip a contact closing and opening member in opposite directions successively.

Further objects and advantages of the invention will be apparent from the following description and from the accompanying drawings, in

which:

Fig. 1 is an elevation of one form cf switch embodying this invention, the cover being partially broken away for the sake of clarity.

Fig. 2 is a. sectional view taken on the line 2 2 of Fig. 1 showing one form of pivotal connection between the spring and the movable switch member.

Fig. 3 is a perspective view of one form of movable member.

Fig. 4 is a perspective view of the pivotal link connecting the spring with the movable member.

Fig. 5 is a perspective View of the spring.

Fig. 6 is a view corresponding to Fig. l but showing a modified form of the invention.

Fig. 7 is a view showing the structure of Figl 6 which pivotally connects the spring with the movable member.

Fig. 12 is a sectional view of another modificai tion of the invention taken on the line I2-I2 of n Fig. 1a.

Fig. 13 is a sectional view taken approximately on the line I3-I3 of Fig. 12.

Fig. 14 is a view corresponding to Fig. -13 but showing the switch in its alternative position.

Fig. 15 is a perspective view of the movable member of Figs. 12 to 14.

Fig. 16 is a sectional view showing another use of the spring of this invention.

Although this invention may take numerous forms, only a few have been chosen'for illustration. of the preferred forms as to general operation. The switch includes a housing II, an .actuating lever I2 and an operating or contact carrying member I3. The` actuating lever I2 is connected to the operating member I3 through a relatively The form shown in Figs. 1 to 5 is typical y closely coiled spring I 4 in a construction which comprises a major feature of this invention. In one commercial embodiment of the invention the coils are 5*," apart longitudinally of the spring at the body portion of each coil. Since the construction at rst glance may seem to be similar to other switches in including the three main elements I2, I3 and I4, it may be pointed out that the spring I4, though positioned at the top of Fig. 1, is pressing the operating member I3 downwardly about pivot I5 instead of urging it upwardly as those skilled in the art would expect from the position of spring I4. The significance of this unusual arrangement can be described better after describing other details of the switch. The switch shown in Fiss. 1 to 5 is a multicircuit switch including four pairs of contacts I3, II, I8 and I3, only one contact of each pair being visible in Fig. 1. The operating member is provided with circuit bridging contacts 2I, 22, 23 and 24, which in fact may be considered parts of the operating member. In the position shown in Fig. 1 bridging contact 22 is bridging the flxed contacts I1, and bridging contact 23 is bridging the fixed contacts I9. Upon operation of the lever I2 the operating member would be shifted sothat the bridging contacts 2I and 24 would .tacts as occasion may require. Inasmuch as the operating member operates in the head of a T-shaped housing, holes may be provided or drilled in the four1 positions shown in Fig. 1 and a pair of contacts provided in each position.

In order to obtain satisfactory performance of a contact switch of this general type (as disitingiushed from the more expensive, more complicated and bulkier knife switch) it is necessary that a firm pressure be maintained between all contacts. Since the available contact pressure is all derived from spring I4, it is desirable that this Pressure be divided evenly between the various contacts, and, accordingly, the bridging contacts are all spring mounted. Thus, as seen in Fig. 3, the bridging contacts 2I and 22 are both urged to their extreme positions by a spring 23 which operates at the centers of the bridging contacts so that each bridging contact may rock about the center point to accommodate itself to unevenness in the positioning of the fixed contacts. Furthermore, the fixed contacts may be adjustably positioned as illustrated in Fig. 1.

Maintenance of contact pressure None of these precautions will in themselves insure the maintenance of the contact pressure while the switch is being operated. It is evident that to shift the operating member I3 from the position shown in Fig. 1 to the alternative position it is' necessary that the force applied thereto be shifted from a downward direction to an upward direction as seen in Fig. 1. As this force passes through the dead-center position the contact pressure must of course be zero. Furthermore, as the preure approaches the dead-center position the contact pressure would, in an :ordinary switch, gradually decrease. If the cong I3 is shifted through the entire dead-center zone instantaneously or with a snap action no matter how slowly the actuating lever I2 is operated. The reason for this can be explained better with respect to Figs. 6 and '1, in which the parts are numbered the same in so far as they have been described heretofore. l

In Fig. 6, as in Fig. l, the spring Il is a coil spring which is under compression as well as being distorted laterally. It wil be observed that 'respectively bridge contacts I3 and contacts I8. A

it presses against the wall portion 28 of the housing, which therefore may be considered a stop for th'e spring. This wall portion holds the spring I4 under compression by restricting its lateral distortion. 'Ihe compressional force of the spring is exerted on the operating member I3 in the direction of the arrow 29 which maintains the operating-member I3 in its illustrated position, thus maintaining an adequate contact pressure. The lateral ilexing of the spring Il probab'ly causes it to exert some pressure in the direction of arrow 2l but the spring is sulciently compressed so that any force in. the direction of the arrow 30 is greatly overbalanced by the compressional force and hence the force in the direction of arrow lll may be ignored. As the actuating lever I2 is moved upwardly, it comes to the position shown in full lines in Fig. 'I bel fore the operating member I3 moves. When the actuating lever I2 is in the position shown in full lines in Fig. '7 the spring Il will have assumed approximately the position shown in full lines in Fig. 7, but it will be observed that its compressional force is still exerted on the operl ating member I3 in the direction of the arrow 29. It will be understood of course that the compressional force of the spring is exerted longitudinally of that portion of the spring which is closest to the operating member I3. Now as the actuating lever I2 moves even a slight amount further toward the dotted line position inFig. '7, the spring I4 snaps to the dotted line position shown in Fig. 7. It will be observed that in this position its compressional force is in the direction of arrow 30 and hence the operating membei` I3 immediately snaps to the position shown in dotted lines.

Snap movements of the operating members can of course be obtained in other manners. It is important to notice therefore that this switch provides an instantaneous shift of pressure through the dead-center zone. In Fig. 7 the spring I4 is shown in full lines approximately in its dead-center position butthe pressure it exerts is still in the general direction of arrow 29. In other words, although the spring may pass slowly through its dead-center zone, the pressure shifts instantaneously. It shifts not as the spring passes through its dead-center zone but as the spring snaps away from the deadcenter zone after passing therethrough.

Pivotal spring connection It will be observed from Fig. 7 that when the spring snaps from the full line position to the dotted line position its left end changes its angle with respect to the operating member I3. In the full line position it approaches the operating member in the direction of arrow 29, whereas in the dotted line position it approaches the operating member in the direction of arrow 30. It appears therefore that in order to get full advantage of the instantaneous shift of pressure the spring I4 must have a pivotal connection of some sort with the operating member I3. Two generaltypes of this pivotal connection have been shown. In Fig. 1 the spring bears on a stirrup 32 which swings within the operating member I3 from notches 33, the stirrup having protruding ends 34 which rest in said notches. The spring acts on the bottom or central mem ber of this stirrup. In the formof the invention illustrated in Figs. 1 to 5 the spring is shown provided with a shoe 36 which is notched to ride on the stirrup 32. However,` the stirrup 32 may be provided with a projecting lug extending up into the spring. The illustrated notch, however. may have some advantage in permitting pivotal movement between the stirrup and the spring to supplement the pivotal movement between the stirrup and the operating member I3.

In the form of the invention shown in Figs. 6 to 11, and as seen best in Fig. 9, the stirrup is omitted and instead the spring I4 is provided with a shoe 38 which rides directly in the not-ches 33. The notches 33 may be provided with a widened seat 39 which permits the shoe 38 to slide from side to side therein to increase the torque arm of the spring pressure about the pivot I just as the swinging of the stirrup 32 seems to increase the torque arm of the spring I4 abouttage of long life and longitudinal compressibility and it has the further important advantage due to the configuration thereof of confining its -fiexing under the circumstances here described to the plane perpendicular to the pivot l5. This causes the spring to track in a single longitudinal space and makes it unnecessary to provide any side guides for the spring, which would in,- evitably increase the friction of its movements and would therefore be likely to make the results less satisfactory than with the present spring.

In Fig. 10 a modified form of the bridging contacts has been shown, being given the numbers 2i', 22', etc. It will be observed that in this instance the bridging members are bowed and their resiliency is relied upon in lieu of spring 26. Their bowed shape permits them to rock so as to equalize the contact pressure between the two ends of each bridging contact.

Figs. 12 to 14 illustrate another form of operating member, which in this instance has been numbered 4I. In this instance the operating member is provided with a fulcrum vane 42 instead of being mounted on a pivot. The vane 42 rocks in a. groove 43 formed in the housing 44, which may otherwise be similar to the housing 28. The vane 42 may rest against the bottom of the groove or it may merely serve as a key, operating member 4I being provided with rockers 46 resting on the Wall of housing 44.

A different form of bridging contact has been shown in the operating member 4I. It comprises a rigid plate 41, which may be considered the bridging portion, having' a contact bearing portion 48 and a reinforcing fiange 49 which rides in a groove 5I in operating member 4 I The flange 49 is in turn provided with a central extension 52 (Fig. 13) and is bent over at its rear end at 53 to limit the movement of the bridging portion 41. The bridging portion 41 is urged toward the contacts I 6 by a central spring 54. The ange 49 and extension 52 should fit loosely enough within the operating member 4I to permit the bridging portion 41 to rock enough to equalize the contact pressure.

In Fig. 16 an additional form of switch has been shown which shows another use for the fiat spring I4. In this instance it is simply slipped into slots 6I and 62 in the actuating member 63 and the operating member 64 respectively by being slid into the end of the slot which is exposed when the cover is removed. The actuating member 63 would of course be provided with a suitable actuating lever external of the casing.

From the foregoing it is seen thatl a switch is provided in which the contact pressure is adequately maintained by the operating spring until the instant that the spring snaps to its alternative position and hence operates the switch by moving the operating member thereof. It may be observed that this operating spring really serves as two elements. That nearer the operating member is a pressure exerting portion which constantly exerts a pressure on the operating member. The more remote portion of the spring is a direction controlling portion which snaps from the position shown in full lines in Fig. 7 to the position shown in dotted lines, thus changing instantaneously the direction of the force applied by the pressure portion. Because of its flat coil shape the flexing of the spring is confined substantially entirely to the desired direction so that its action is always the same. I

Although I have described my invention in the preferred embodiments, it is understood that the invention is not limited thereto, but changes and modifications may be made therein, all within the scope of the appended claims.

I claim:

1. A switch including an actuating member, a pivoted contact bridging member having an edge rim and a cavity below the edge rim, a spring support pivotally mounted on said edge rim and having a portion extending into said cavity, a s'pring operatively connected at one end to said actuating member and supported at the other 4end upon said spring support with said other end of said spring extending into said cavity.

2. A switch including actuating means having a pivot portion on which it is pivoted, contact bridging means having an axis portion, a coiled relativelyiiat spring operatively connected at one end with said actuating means, support means supporting the spring at the other end with said support means having a pivot portion pivotally connected with said bridging means at a point displaced substantially longitudinally from said axis portion and intermediate said axis portion and the actuating means pivot portion in said switch, with the distance between the other end of saidspring on the spring support means and the actuating means pivot portion being greater than the distance between the actuating means pivot portion and the point of pivotal connection for the spring support means and the contact bridging means, and stop means for limiting the lateral bowing of thespring in each of two positions of rest therefor positioned so as to maintain said coiled spring under compression at said positions of rest and provide a spring force for application to the spring support means.

3. A switch including a pivotal bridging member movable between two positions, axis means pivotally supporting said bridging member, a pivotal actuating member having an axis, a compressed coil spring arranged for bending between said actuating member and bridging member,

said spring being operable to move the Vbridging member from one of said positions to the other in response to the movement of said actuating member and to retain said bridging member in the position into which it is moved, said spring being connected at one end to said actuating member for side to side bending movement thereby, means for limiting the sidewise bending movement of said spring to two extreme positions, with the spring force applied on said bridging member when the spring is in one of said extreme positions being opposite from that when the spring is'in the other of said extreme positions, andA means pivotally connected to the bridging member andy pivotal independently thereof for supporting the opposite end oi' said member, with saidaxis means and axis portion being arranged in a substantially common sectional plane of said bridging member and said axis means being displaced away from said axis portion, with said axis portion being positioned in a substantially longitudinal direction vintermediate the axis for said actuating member and said axis means, said spring supporting means on movement of said actuating member permitting said spring to snap from one of its extreme positions to the other prior to any substantial change in the direction of the force thereof being applied to said bridging member for moving the same.

4. In an electric switch having operatively associated xed contact means and movable contact means, the combination of means for eiiecting a snap movement oi said movable contact means in response to a relatively slow actuating movement for operating said switch including a pivoted bridging member carrying said movable contact means and having an opening therein. a pivoted actuating member, a spring arranged in compression betweenl said actuating and bridging members and laterally movable intermediate its ends in response to movement of said actuating member to move said bridging member to open and close said movable and fixed contact means, with one end of said spring being connected to said actuating member, a spring support pivotally mounted on said bridging member and having a portion extending into said opening, with the other spring end being supported on said extending portion, the pivotal axes of said supporting member and bridging member being arranged in a common sectional plane in said bridging member, and means for limiting the lateral movement of said spring to two operating positions, said spring in one of said operating positions being bent in a direction to apply a pressure on said bridging member in one direction to one side of said plane, and being reversely bent in the other oi said operating positions to exert a pressure on said bridging member in an opposite direction, with movement of said actuating member progressively deflecting said spring until it becomes compressively unstable for one of said bent positions at which time it immediately snaps to a reversely bent position and-with said spring pressure being applied in one direction on said bridging member until immediately after-said snapping action.

5. A switch including insulating frame means, actuating means, a contact bridging member having side portions and an opening therebetween, a pivot portion on said bridging member pivotally supporting said member on said frame means, a substantially U-shaped spring support member with a connecting portion extending into said opening and being pivotally connected with said bridging member at said side portions and at an axial line which is intermediate said connecting portion and said actuating means in a substantially longitudinal direction in said switch, a relatively 'fiat coiled spring operatively connected at one end with said actuating means and extending into said openingat said other end and operatively connected with said connecting portion of said spring support, stop means for limiting the lateral bowing of said spring in a position of rest thereof and positioned so as to maintain said spring under compression to provide a spring force for application to said spring support member and contact bridging member, and contact mielns on said bridging member movable therew 6. In an electrical switch including a pivoted actuating member, a pivoted bridging means having-an opening therein, means operatively connecting said actuating member and bridging means including a coil spring, with movement of said actuating lever moving said spring with a sidewise motion to move said bridging means, said spring being connected at one end to said actuating member, with the other end thereof pivotally supported on said bridging means, and a spring supporting element having an axis portion pivotally mounted on said bridging means with a second portion extending within said opening, said other spring end being supported on said second portion and within said opening so as to thereof pivotaily supported on said bridging member, and means having an axis portion pivotally mounted on said rim portion and a second portion extending within said opening, said other spring end being supported on said second portion and extending into said opening so that the distance between said two spring ends is normally greater than the distance between said one spring end and said axis portion.

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