US2528756A - Toggle-lever switch - Google Patents

Description

Nov. 7, 1950 A. KAsER TOGGLE-LEVER swrrcu Filed July 10, 1947 INVENIT'OR ALBERT KASER BY W M -vl/M ATTORNEYS Patented Nov. 7, 1950 2,528,758 TOGGLE-LEVER swrrcn Albert Kiser, Zng, Switzerland, assignor to Landis 8; Gyr, A. G., a corporation of Switzerland Application July 10, 1947, Serial No. 760,005 In Switzerland July 23, 1946 3 Claims.

The invention relates to a toggle-lever switch and more particularly to a switch with a flexible spring which is moved to open and close a circuit.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Toggle-lever switches of the prior art have, as a principal defect, the fact that the entire force of urging pressure, between the moving contact and the stationary contact, is that of contact pressure, and, as a result, this contact pressure falls to zero immediately before switching movement occurs. If the switch is being thermostatically operated this condition may last an appreciable time, causing sparking at the contacts resulting in undesirable effects in the circuit, for example, radio interference. The burning of the contacts resulting from the sparking will lead to an alteration in the tumbler mechanism of the switch since the contacts themselves are the motion limitin stops. Another result of the existence of the sparking often is fusion of the contacts.

An object of the present invention is to provide a toggle-lever switch in which the contact pressure does not fall to zero immediately before switching movement occurs. Another object is to provide such a switch in which stops for limiting the motion of the toggle spring are independent of the contacts, and in which at least one switch contact is resiliently mounted.

Of the drawings:

Figure l is a view in side elevation of an embodiment of the present invention with portions broken away for clarity in which the contacts are in open position:

Figure 2 is a view in elevation as in Figure 1 in which the contacts are in closed position;

Figure 3 is a plan view of a toggle spring embodying this invention; and,

Figure 4 is a view in section taken along the line 4-4 of Figure 3.

Referring now in detail to the drawings, in Figure 1, I denotes a mounting plate, bent at right-angles to form a flange at one end shown in the right hand side of the figure, and is provided in front and rear, at the other end, with two extensions 2, only the rear one of which is shown in the drawing, the front one having been cut away for the sake of clarity. One arm of a setting lever 3, of bell-crank type, engages between the two extensions 2, whilst the other arm of said lever runs parallel with the mounting plate I. The setting lever 3 is pivotally mounted on an axis 4, between the two extensions 2, and is provided with a set screw 5 at the right end of its horizontal arm. Both the downwardly bent end of the mounting plate I and the vertical arm of the setting lever 3 are provided with knifeedge bearings 6 and 1 respectively, in which the corresponding knife-edges of a toggle spring 8 can be mounted. The shape of this latter is best seen from the plan, Figure 3 and the crosssection in Figure 4. It is evident from Figure 3 that the right hand end of the toggle spring is very substantially stifiened, both longitudinally and transversely by two edges 9 and Ill-bent downwards at right angles and also by a downwardly pressed transverse rib II, whilst its left hand end formed by stamping out a portion I2 into a flexible contact tongue l3 and a knifeedge tongue I4 has no stiffening. The tongue I3 is provided with a hole I5 to accommodate a contact member not shown in Figure 3. The left hand end of the tongue I4 has a slightly curved knife-edge I6 which can be inserted into the bearing 6 on the setting lever 3. On its right end, the toggle spring has two further knife edges I! and I8, which can be mounted in knifeedge bearings l in the plate I. The bent edges 9 and I0 are provided at corresponding points with rounded extensions I9 and 20, respectively, Which-as can be seen in Figure 1-overlap the plate I laterally. It can also be seen from Figure 3 that an opening 2| serving as a stop, is provided in the stiffened portion of the toggle spring. Figure 4 represents a cross-section of the said toggle spring, the two turned-up edges 9 and I0 and the transverse rib II being clearly shown. As may be seen from Figure 1, an adjustable screw stop 22 is provided in the plate I, its lower end having a groove 23, so that an upper abutment surface 24 and a lower one 25 are formed. The screw 22 is mounted in the plate I, exactly opposite the opening 2I in the spring 8, and the two abutment surfaces 24 and 25 are respectively above and below the surfaces of the toggle lever. Moreover, the diameter of the opening 2| in the spring 8 is such that, when the parts are being assembled, the head 26 resulting from the formation of the groove in the screw stop can be inserted without difllculty, whilst after assembly, the centre of the opening 2| does not coincide with the axis of the screw 22, so that only that portion of the rim of the opening 2| which is nearest to the rib II can bear against the abutment surface 24 or 25. In Figure 3, in which these conditions are shown, the cross section of the grooved portion of the screw stop is indicated by 23!. In Figure 1 the toggle-lever switch is represented in the off po sition, that is to say, the stiffened portion of the spring 8 bears on the lower abutment surface 25 of the screw 22 and the tongue I4 is bent downward to a considerable extent. The resilient contact tongue l3 lies in the same plane as the stiffened portion of the toggle-lever spring. The left end of the tongue I3 carries a riveted contact member 21, and at the same point bears lightly against an adjustable stop 28. Facing these, and on about the same level as the knife edges 6 and 1, is a second contact 29 which is also adjustable. Figure 2 on the other hand, shows the toggle spring in the switched-on" position, that is to say the stiffened portion of the spring 8 bears against the upper abutment surface 24 of the screw 22, and the tongue I4 is only very slightly depressed. The tongue I3 is now bent slightly upwards since the contact 21 attached to it bears against the second contact 29.

The toggle-lever switch described can be perated in many ways. Th drawing shows. by way of example, the switch operated by a temperature sensitive plunger device of known type. In Figures 1 and 2, 39 denotes a flange which is secured to a casing-not further represented and carries a fixed plunger tube 3| of material with a high coefllcient of expansion. Arranged in the usual manner, inside said tube, is a socalled basis rod of material with the lowest possible coeflicient of expansion, its lower end being firmly attached to the bottom end of the tube 3|. It will be readily evident that as the temperature to which the plunger device is exposed rises the plunger tube 3| will become longer, whereas the length of the basis rod will remain almost unchanged; Since the flange 39 is in a fixed position, a relative displacement of the upper end of the basis rod, in relation to the flange will occur, the end of the basis rod moving downwards in this case, whereas it will move upwards should the temperature fall. This arrangement is combined with the above described toggle-lever switch by bringing the insulated upper end 32' of the basis rod of the plunger into operative connection with the tongue l4 of the togglelever switch.

As will be readily evident from Figures 1 and 2, the correct adjustment of the tension of the toggle spring can be effected by shifting the knife edge 6 in an approximately horizontal direction, by means of the set screw 5.

The arrangement described functions in the following manner: 1

When the tension of the spring has been correctly adjusted, the toggle-lever switch is in the "off position shown in Figure 1. If the temperature of the medium to be controlled falls, the basis rod 33 will move upwards and bring about elastic deformation of the spring I4, there- 'by setting up an external pressure against the I said contact pressure.

toggle-lever switch. Consequently, the resultant force acting upon. the lower abutment surface 29 of the screw 22, namely .the resultant of the said external force and the force of the toggle spring, slowly decreases. The moment this force is reversed by the action of the continuously rising basis rod 33, tumbler operation starts, that is to say, the stiffened portion of the toggle-spring, which, despite the gradual decrease of the downward force, stillcontinues to bear on the lower abutment surface 25, suddenly changes its position, springs upwards and bears against the upper abutment surface 24'. The same movement that is made by the stiffened portion of the toggle spring is shared by the tongue I3. However, the contact 21 thereon touches the counter contact 29, before the said movement is completed. Consequently, the tongue I3 is stressed, and at the end of the switc ling movement, a certain contact pressure, due' to the stressing of the spring l3, exists between the contacts 21 and 29. On the other hand, as can easily be seen, the pressure of the toggle spring against the abutment 24 is reduced-taking the leverage into consideration-by the amount of However, the conditions are so arranged that there is a comparatively large surplus of residual pressure which secures the switch in the position it has attained. It should'be noted that the tongue I4 does not become separated from the insulated upper part 32 of the basis rod 33, during the switching operation. On the contrary, it merely undergoes such elastic distortions as, on the one hand, enable the switching to be effected, and on the other hand do not involve any interruption of the contact between the upper end of the basis rod and said tongue. Moreover, the dead point in the on position of the switch has not yet been reached. In that position, as is shown in Figure 2, the tongue I4 is still slightly depressed and bears against the basis rod. If, owing to a rise of temperature in the medium to be controlled by the plunger, the basis rod gradually descends, the tongue l4 follows this movement, at once, and again undergoes elastic deformation so that the force directed upwards against the abutment surface 24, also diminishes without the stiffened portion of the toggle spring taking any part in that movement for the time being. Before any movement is set up in this portion, the aforesaid deformation of the tongue 14 reacts on the stiffened portion of the toggle spring, in such a way that the force acting against the abutment surface is reduced to zero. Up to this moment, however, the stressing of the spring l3, and, accordingly, the mutual pressure of the contacts 21 and 29, remains unchanged. If, as the result of the continued descent of the basis rod 32, the external pressure falls below the level corresponding with the sum of the interior transverse force of the toggle spring and the contact pressure of the spring I3that is, if the resultant force begins to act in the downward directron-the tumbler operation takes place instantly, the stiffened portion of the toggle spring Jerks downwards until it bears against the lower abutment surface 25, the tension of the tongue I3 is relieved, the contacts 21, 29 separate instantly, and the toggle-spring system returns to the "off position represented in Figure '1. The separation of the contacts 21, 29 occurs at the moment when the stiffened portion of the toggle spring is in a position about midway between the two abutment surfaces 24, 25.

As follows from the above description, the electric circuit passes between the contacts 21 and 29, that is to say, the contact 29, the toggle spring 8 (together with the attached mount I and setting lever 3), and also the stop 28, may come under voltage. It is self-evident, therefore, that these parts should be electrically insulated from each other, and also from earth. Acordingly, the upper portion 32 of the basis rod 33 must be designed as an insulated press stud which can be made, for example, of glass, steatite, etc. The stop 28 may also be in the form of a contact, in which case, it is esesntial that it should be moved upwards, in Figure 1, sufficiently far for the spring I3 to be adequately stressed.

Instead Of making the. tongue 13 resilient, it might, in another embodiment, be of rigid construction, the contact 29 on the other hand, being resiliently mounted.

The above-described toggle-lever arrangement has, in common with the known arrangement operating only on one side of the dead point, the advantage that it is operated in only one direction, from outside, whereas, in the other direction, it functions automatically. Further advantages result from the circumstance that the tilting movement is restricted solely by the two abutment surfaces 24 and 25, that is to say, independently of any burning or wear of the contacts, so that alterations in the tumbler mechanism as the result of burned contacts, are reduced to a minimum. Furthermore, the mutual pressure between the contacts is fully maintained until the switching operation is performed. Thus, in contrast to the known toggle-lever switches, there is no diminution of the contact pressure prior to the tilting with resultant sparking, so that the device functions without radio interference. The described toggle-lever switch is also highly sensitive, because, in the on position, the resulting impact force against the abutment surface 24 is diminished by the degree of the contact pressure-which is equivalent to a mechanical compensatin-so that, despite a contact pressure of, for example, 15 grams, a working stroke of, for example, only 0.02 mm., is needed to cause the snap action to occur. 7

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made\ therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantage.

What is claimed is: p

1. A toggle lever switch comprising a toggle lever spring having a rigid portion, spaced pivot points, and a resilient tongue portion extending forwardly from said rigid portion and having its free edge mounted in the forward pivot point; an actuator for said spring located between said pivot points and acting upon said resilient tongue portion; switching contacts including spring mounted and normally stationary auxiliar contacts; and stops spaced rearwardly from said contacts for limiting the movement of said toggle spring in each direction.

2. A toggle lever switch comprising a toggle lever spring having a rigid portion, spaced pivot points, a resilient tongue portion extending from said rigid portion and having its free end mounted in the forward pivot points, a resilient arm portion extending from said rigid portion forwardly beyond said tongue portion; an actuator for said spring located between said pivot points for acting upon said resilient tongue portion; switch contacts including spring mounted and normally stationary auxiliary contacts, said spring mounted contact being positioned on said arm portion of said lever spring; and stops spaced rearwardly from said contacts for limiting the movement of said toggle springs in each direction.

3. A toggle lever switch comprising a toggle lever spring having a rigid portion, spaced pivot points, a resilient tongue portion extending from said rigid portion and having its free end mounted in the forward pivot points, a resilient arm portion extending from said rigid portion forwardly beyond said tongue portion, an actuator for said spring located between said pivot points for acting upon said resilient tongue portion; switch contacts including a contact mounted on said resilient arm portion, a normally stationary auxiliary contact, and a stop in vertical alignment with said auxiliary contact for limiting the movement of said contact mounted on said arm portion; and vertically aligned stops spaced rearwardly from said contacts for limiting the movement of said toggle springs in each direction. ALBERT KASER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,215,665 Landis Feb. 12, 1917 1,622,721 Hook Mar. 29, 1927 2,418,831 Hamilton Apr. 15, 1947 FOREIGN PATENTS Number Country Date 862,910 France Dec. 23, 1940

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