US2685007A - Electric snap or quick break switch - Google Patents

Description

y 1954 K. FISCHER ELECTRIC SNAP OR QUICK BREAK SWITCH Filed Feb. 14, 1951 Patented July 27, 1 954 UNITED STATES TENT OFFICE Karl Fischer, Oberderdingen (Wurttemberg), Germany Application February 14, 1951, Serial No. 210,870

Claims priority, application Germany October 2, 1950 5 Claims.

This invention relates to an electric snap or quick break switch of the type having a switch spring designed in such a way that on exceeding a predetermined position, the spring carries out a jerk-like motion (quick break switching) so that the formation of electric arcs at the contacts such as they are unavoidable in case of a creeping switching motion, are avoided. This is particularly important where the switch is intended to break high current intensities and is operated by the continuously moved control member of a governor (heat, pressure, quantity, moisture governor or the like) The present invention has special reference to quick break switches of the type comprising a switching spring consisting of two coherent arms whose free ends are supported against abutments in such a way that one of the spring arms shortened by bending is under a compressive stress and exerts upon the other arm, being under a tensile stress and therefore being supported in an opposite direction, a force whose direction is determined by the chord or subtense connecting the point of connection of the two arms of the spring with the abutment of the compression sprin arm.

As lon as this spring force is inclined in a predetermined direction in relation to the straight line (line of tipping) connecting the abutment of the tension arm of the spring with the point of division of the two arms of the spring, this force even in case of a varying amount of the angle of inclination will always exert a transverse force against the tension arm of the spring, retaining the same in an end position defined by a stop (e. g., a contact). However, as soon as the spring force takes up the least opposite inclination in relation to the said line of tilt ing, the transverse force produced by the spring force will also convert its direction and therefore move the tension arm of the spring into another end position. Hitherto, this change of the direction of the spring force was caused by fixedly positioning the end of the tension arm of the spring, while the free end of the flexed or compression arm of the spring was linked to the end of a one-armed lever which could be swung by hand or by the regulating power of a governing member in both directions beyond the line of tilting of the tension arm of the spring. However; the use of a one-armed lever had the disadvantage that relatively large amounts of displacement were required, because the abutment of the compression arm of the spring had to traverse the whole way up to the position oftilting. The amounts of displacement, however, could not be shortened beyond a measure defined by the safety of the switch against vibration, although the governor interval was increased by that length of the amounts of displacement in an undesirable manner.

It is an object of the present invention to provide a snap switch which avoids the said disadvantages of the existing types.

With this and further objects in view, according to the present invention the ends of the two arms of the spring are linked to the opposite ends of a two-armed lever. As a result, by swinging the two-armed lever not only the abutment of the compression arm of the spring is approached to the line of tilting, but beyond that by displacement of the abutment of the tension arm of the spring the line of tiltin is also approached to the abutment of the compression arm of the spring, so that this abutment has totraverse only one half of the amount of displacement so far required in order to cause snapping over of the switch. It will be understood that in this manner also the governor interval between two opposite switching operations is substantially shortened. The governor interval can be further shortened by imparting to the end of the tension arm of the spring projecting over the abutment a preliminiary bending or flexing stress so that the middle part of the arm on switching will quickly approach the line of tilting.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and appear in the appended claims forming part of the application.

In the accompanying drawing a now preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

Fig. l is a longitudinal section of the switch,

Fig. 2 is a plan view of the switch, and

Figs. 3 and 4 are diagrammatic views of the switch as per Fig. 1, showing different positions of operation.

Mounted on a base plate 1 of the switch consisting of insulating material is a bifurcated bearing bracket 2 provided with a connecting terminal 3. Swingably mounted in the bearing bracket 2, on a pivot 4, is a two-armed lever 5 which may be provided with a digitally operable grip 6 in order to operate the switch by hand. Each of the two opposite ends of the two-armed lever 5 is formed with a bearingsocket 1 or 8, respectively, consistin of a through-going transverse groove. The twobearing sockets and .l serve .for linking the two arms 9 and I!) of the snap switch.

Arm 9 of the switch spring consists of a rectangular frame whose one transverse part I l carries one or more switch contacts [2 and is swingable between two stops it and it which are preferably adjustable and are provided, for instance, with connecting terminals H5 or 15, or the like, in such a way that the switch can be used selectively as a circuit closer and circuit breaker and as a change-over switch. The second. transverse part I! of the frame-shaped spring arm 9 serves for clamping the switch spring. However, it is not fixedly clamped but according to the present invention it is operatively connected to the twoarmed switch lever 5 into whose bearing socket I it engages with its edge-shaped inner border. The second spring arm i is punched out of the inner surface of the frame-shaped spring arm 9 in such a way that it is fixedly cohering with the transverse part H thereof. The spring arm it may also be formed by a separate part which is connected, for instance, riveted or welded, to the transverse part ll thereof. The free end of the spring arm ill engages edge-fashion into the bearing socket 8 at the opposite end of the two-armed switch lever 5, in such a manner that each of the ends of the two spring arms 9 and H3 is operatively connected to one arm of the two-armed switch lever 5. The spring arm 19 is shorter than the substantially straight spring arm 9 but still so lon that it cannot become completely straight in any position of the switch lever clamped between the two spring arms. It rather remains always in a flexed condition and therefore is always under a compressive strain. The spring arm iii therefore will exert a tension force upon the spring arm 5 which force, depending on its position in relation to the line of tilting of the spring arm 9, tends to retain the same in one of its two end positions, for instance, in the position shown in full line, or to swing the same out of this position into the opposite end position shown in dot and dash lines.

The response of the switch spring 9, it will be caused by swinging the two-armed switch lever 5 which may either be effected by means of the digitally operable grip 8, by hand, or for instance (as shown in Fig. 4) by means of any governing member is acting for instance directly upon the switch lever. Set screws [9 and 29 serve for limiting the stroke of the switch lever 5 and thus to enlarge or reduce the amount of displacement S required for exceeding the line of tilting (this amount being exaggerated in the drawing for the sake of clarity). A further set screw 2| adapted to act upon the transverse part ll projecting beyond the link point 1 of the spring member 3 may be used for approaching the position of the spring member 9 to the line of tilting, in order to reduce the amount of displacement S (Fig. 3) and to impart a preliminary flexing tension to this spring arm 9. Thus its snappin over into the opposite end position is favored and it is possible to operate with smaller adjusting forces. The preliminary tension of the spring arm 9 caused by the set screw 2| can be driven so far (Fig. 4) that the spring forces occurring admit only a predetermined end position (as indicated in full lines) while the opposite end position (shown in dot and dash lines) can be taken up only as long as the two-armed switch lever 5 is swung out of its initial position by a governing power over-powering the preliminary tension of the spring arm 9'. When this governing power discontinues, the two-armed switch lever 5 is immediately moved back into its initial position (shown in full lines) by the preliminary tension of the spring arm 9, so that the switch spring 9, ill will also return into its initial position in which it engages the stop l3. Accordingly the switch without alterations of its elements or its construction can be used both as a switch with two fixed positions of rest (Figs. 1 to 3) or as a switch having only one fixed position of rest and one position of constraint.

It follows from the use of a two-armed switch lever 5 to the opposite end of which two spring arms 9 and ill are operatively connected that on swinging the switch lever not only the link point 8 of the compression arm I8 is approached to the line of tilting but simultaneously the link point 1 of the tension member 9 is also displaced in an opposite direction so that each of the link points i and 8 has to traverse only half of the amount of displacement or angle of rotation normally required in order to cause snapping over of the switch spring. By this reduction of the amount of displacement the switch becomes extremely Sensitive and permits to reach very small governor intervals.

It will be understood that the invention is not restricted to the shape of the switch spring or other parts as shown, but the switch spring could be shaped for instance also in such a way that the two spring arms 9 and in are interchanged against each other as regards their position in relation to the longitudinal axis of the switch spring. Also the set screw 2! could be replaced by a fixed stop or a compression spring, or a pressure screw could be inserted between the set screw and the switch spring, for adjustment with the aid of the set screw. The set screw 21 may also be omitted entirely in the construction with two fixed positions of rest. In a corresponding manner the stop '20 could be dismissed entirely in case or" a construction of the switch with'one position of rest and one position of constraint. It is an important advantage of the construction according to the invention that it is able to further reduce the already small switch motion of known snap switches by simple and reliably operating means. It should also be noted that the preliminary flexing tension exerted upon the spring end H by the stop 2i also tends to reduce the length of the switch motion.

While the invention has been described in detail with respect to a now preferred example and embodiment of the invention it will be understood by those skilled in the art after understanding the invention that various changes and modifications may be made without departin from the spirit and scope of the invention and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. An electric snap switch comprising a switch spring having a tension arm and a compression arm, at least one contact on the tension arm. two end stops between which said tension arm is swingable, a two-armed switch lever adapted to swing the compression arm in relation to a line of tilting, the ends of the two arms of the switch spring extending away from the contacts being operatively connected to the opposite ends of the switch lever arms, and adjusting means in the form of a set screw having an end contact with the tension arm for varying the position of the line of tilting of the tension arm in relation to the line of compression force of the compressionarm, said set screw acting upon the end of the tension arm facing away from the switch contact, which end projects beyond the point of connection of the tension arm of the spring on the switch lever.

2. An electric snap switch comprising a switch spring having a tension arm and a compression arm, at least one contact on the tension arm, two end stops between which said tension arm is swingable, a two-armed switch lever adapted to swing the compression arm in relation to,a line of tilting, the ends of the two arms of the switch spring facing away from the contacts being operatively connected to the opposite ends of the switch lever arms, and adjusting means for varying the position of the line of tilting in relation to the line of compression force of the compression arm, said adjusting means acting upon the end of the tension arm facing away from the switch contact, which end projects beyond the point of connection oi the tension arm of the spring on the switch lever.

B. An electric snap switch comprising a switch spring having a tension arm and a compression arm, at least one contact on the tension arm, two end stops between which said tension arm is swingable, a two-armed switch lever adapted to swing the compression arm in relation to a line of tilting, the ends of the two arms of the switch spring facing away from the contacts being operatively connected to the opposite ends of the switch lever arms, and adjusting means for varying the position of the line of tilting in relation to the line of compression force of the compression arm, said adjusting means being in the form of a pressure screw acting upon the end of the tension arm facing away from the switch contact, which end projects beyond the point of connection of the tension arm of the spring on the switch lever.

4. An electric snap switch comprising a switch spring having a tension arm and a compression arm, at least one contact on the tension arm, two end stops between which said tension arm is swingable, a two-armed switch lever adapted to swing the compression arm in relation to a line of tilting, the ends of the two arms of the switch spring facing away from the contacts being operatively connected to the opposite ends of the switch lever arms, and adjusting means for varying the position of the line of tilting in relation to the line of compression force of the compression arm, said adjusting means acting upon the end of the tension arm facing away from the switch contact, which end projects beyond the point of connection of the tension arm of the spring on the switch lever, and being arranged and dimensioned in such a way that it produces on the tension arm a spring force urging the switch spring into a predetermined position of rest which can be over-powered only by a continuously acting adjusting force and on discontinuation of this adjusting force results in an automatic return of the switch spring into its initial position.

5. An electric snap switch comprising a switch spring having a tension arm and a compression arm, at least one contact on the tension arm, two end stops between which said tension arm is swingable, a two-armed switch lever, two bearing sockets on said switch lever which is adapted to swing the compression arm in relation to a line of tilting, the tension arm of the spring being subdivided into two legs enclosing between themselves the compression arm and being interconnected by a cross leg, said cross leg and the free front face of the compression arm being supported in said bearing sockets, whereby the ends of the two arms of the switch spring extending away from the contacts are connected to the opposite ends of the switch lever arms, and adjusting means in the form of a set screw having an end contact with the tension arm for varying the position of the line of tilting of the tension arm in relation to the line of compression force of the compression arm, said set screw acting upon the end of the tension arm facing away from the switch contact, which end projects beyond the point of connection of the tension arm of the spring on the switch lever.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,135,864 Weber NOV. 8, 1933 2,295,463 Fetter Sept. 8, 1942 2,537,682 Ljungfeldt Jan. 9, 1951 2,540,337 Kaser Feb. 6, 1951 2,545,765 Christensen Mar. 20, 1951 FOREIGN PATENTS Number Country Date 929,963 France Jan. 13, 1948

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