US 2537682 A
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Description (OCR text may contain errors)
1951 B. A. H. LJUNGFELDT 2,537,682
ELECTRIC SWITCH Filed Sept. 16, 1947 5202A? fifA/umsrezar 5/ Patented Jan. 9, 1951 Enact-arc sWI'ron Titer e H ieie hieeg t et o m w d s Aesthet cs e em 16,1941 Sir-m In Sweden Septe b r 24, 1
.3. Glaietsr 1 This invention relates to electric switches of the snap-action type wherein one of the contact memrs n the rm 0i a bla e w ch s moun e for rocking movement at one end, whereas" the other end thsreei is tree and a a ted. o cooperate with the other contact member, and wherein furthermore the blade is provided with a resilient ,l. .2411? with th e 9 thetenelis bearin with a. cer Pressure against a suitable abutment member. In such a switch the line of engagement between the tongue and the abutment member norma ly lies on one side of the plane through the base of the tongue and the rocking axis of the blade, and when said line of engagement is approached to ward said plane, as by moving the tongue, the tension of the resilient tongue is increased until the line of engagement has just passed the plane, when the blade is suddenly rocked by the tongue.
The main object of the present invention is to provide an electric switch of the above-mentioned type wherein the blade-shaped contact member is caused to slide in .a longitudinal direction before being rocked so that the contact surfaces will be rubbed against each other and thus kept clean and free from oxide films and other impurities.
Other objects of the invention will appear from the following description of a preferred embodiment of the switch reference being had to the accompanying drawing, wherein:
Fig. l is a side elevation of the switch in its closed position;
Fig. 2 is a similar view of the switch in its open position;
Fig. 3 is a bottom plan view of the switch; and
Fig. 4 is a plan view of the blade-shaped contact member used in the switch.
In the drawing I designates a base plate made from a suitable insulating material, such as Bakelite. The base plate is provided on its underside with two spaced bearing members 2 and 3 having bores through which a pin 4 extends. The pin ti carries an operating lever, or arm, 5 which may be rocked on the pin and which extends through an opening provided in the base plate l. A bracket 6 having a contact '1' is secured to the under side of the base plate E near one end thereof, as by a screw 8. A blade-shaped contact member 9 has a free end extending into the space between the bracket 65 and the base plate I and carries a contact ll for cooperation with the contact 7. The blade 9 preferably consists of a leaf spring in which a resilient tongue 12 has been formed, as by stamping or cutting out a U-shaped aperture, compare also Fig. 4. The
2. base ll of the tongue 12 is adjacent the free end of the blade 9-, and the tongue extends rear-.- wardly. Between the free end of the tongue It and the opposed transverse edge It of the U? shaped aperture in the blade 9 there is a space adapted to receivethe. end of: the rockable lever,
or arm, 5. If desired the blade i3 may also be provided with a rear U..-shapedextension l3 which is. flexible so. as to. permit longitudinal movement of the. blade. and may. be secured to the base plate at its rear end, as by a screw l0. ihe portion l3 of the blade is not necessary, however, and the blade can terminate freely some distance behind the edge It.
The end of the operating lever, or arm, 5 extending into the space formed between the edge 16 and the free end of the tongue 12 has preferably two oppositely located indentations or grooves 54 and i5 for receiving said tongue and said edge, respectively, the distance between the deepest points of the indentations being somewhat greater than the width of said space so that the resilient tongue I2 will be placed under tension when the arm 5 is inserted into the aperture in the blade.
Fig. 1 shows the position of the different parts of the switch when the contacts I and II are closed. In this position the free end of the tongue 12 is bent upwards and lies above the blade 9, as shown. When the operating lever, or.
arm, 5 is turned to the left about the pin 4 the blade 9, owing to the engagement of the edge IS with the indentation I5, is moved longitudinally to the right, so that the contact H slides on the contact 1 under the pressure exerted by the tongue [2 and effectively removes oxide films and other impurities which may be present on the contact surfaces. Simultaneously the line of engagement between the tongue I2 and the indentation M is lowered towards the plane through the base H of the tongue and the edge i6 and the tension of the tongue I2 is increased. When during the continued movement of the lever 5 the line of engagement between the tongue and the indentation has just passed the aforesaid plane, the tongue I2 is free to rock the blade 9 about the edge [6 and suddenly moves the blade into the position shown in Fig. 2 in which the contacts i and [I When the lever 5 is again moved to the right the blade is similarly suddenly returned to the position shown in Fig. 1 when theline of engagement between the tongue 12 and the indentation M has been raised above the plane through the base I! of the tongue and the edge l6.
Though the tongue !2 is preferably made in are separated.
one piece with the blade 9, as shown in Fig. 4, it may also consist at a separate resilient member which is secured to the blade in any suitable manner, as by riveting. Instead of a single tongue two or more tongues may be used. Furthermore the operating member may be constructed and shaped in difierent ways within the scope of the invention.
What I claim is:
1. An electric switch of the snap-action type comprising a base member, a first contact member supported by said base member, a second contact member in the shape of a blade supported for rocking movement at one end whereas the other and free end thereof is adapted to cooperate with said first contact member and to be moved towards and away from the latter for closing and opening the switch, said blade being provided with an aperture with an edge forming a fulcrum and with a resilient tongue extending from the free end of the blade toward said edge and terminating freely at some distance from the edge, and a switch operating member rotatably mounted on a pivot in said base member and having an arm with opposite grooves below said pivot and extending into the aperture between the end of the resilient tongue'and the fulcrum edge with the tongue and the edge abutting against the opposite grooves of the arm, the fulcrum edge forming a pivotal connection with the operating member and the arm being so dimensioned as to place the tongue under stress tending to rock the blade with snap-action about said fulcrum edge when the operating member is rotated, and said rocking movement being preceded by a longitudinal movement of the blade-shaped contact member with respect to the other contact member owing to the abutment of the blade edge against the rotatable arm to create a wiping action relative to the contacts.
2. An electric switch according to claim 1, in which the blade is formed by a leaf spring provided with a U-shaped aperture defining the tongue and the opposed edge.
3. An electric switch according to claim 1, in which the blade has a U-shaped extension at the end thereof opposite the free end.
BROR AKE HILDING LIUNGFELDT.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,135,864 Weber Nov. 8, 1938 2,460,087 Hollis Jan. 25, 1949