US2184767A - Electric switch - Google Patents

Description

Dec. 26, 1939. I w. SCHAELCHLIN ELECTRIC SWITCH Filed July 31, 1936 WITN ESSES:

A.TTORN EY Patented Dec. 26, 1939 1 UNITED STATES PATENT OFFICE .....i*f:":l..... Walter Schaelchlin, Wilkinsbnrg, 1a., assignor to -Westinghouse Electric 8'. Manufacturing Comparry, East Pittsburgmla a corporation of Pennsylvania Application July 31,

' 4 Claims.

My invention relates to Switches, or inter-- rupters, for electric circuits, and more particularly to such switches for controlling sequential operation of electrical apparatus, as motors.

One object of my invention is to provide a more reliable, simpler, and less expensive switch for making and interrupting electrical circuits.

Another object of my invention is to eliminate all flexible conductors, or jumpers disposed be tween .the movable contact and its terminal now used by prior art devices.

A stillfurther object of my invention isithe provision of carrying large currents, to be inter rupted by switchingmeans, through a pivot dis-' posed between an electric terminal and the movable contact of a switching device energized from such terminal.

' The usual switch design, of switches generally of the class to which my invention relates, in cludes a suitable bearing for the moving contact arm and a flexible shunt for carrying the current from the movable contact to its stationary terminal. A switch of this type, representing the prior art, does not ofier great difliculties for switches of relatively low current carrying capacities, but become cumbersome, unreliable, and expensive for switches having a large current carryirg capacity.

A specific object of my invention is a contact arrangement that eliminates both the usual bearing for a movable contact and the flexible shunt disposed between the movable contact and it terminal.

One general object of my invention is the provision of switching devices of relatively large current carrying capacities that are simpler, more reliable, and less expensive than the switching devices of the prior art for like capacities.

Other objects and advantages will become more apparent from a study of the following specification when considered in conjunction with the accompanying drawing, in which:

Figure 1 is a side view with certain parts in section along a vertical plane; Y

Fig. 2 is a front view of the subject matter shown in Fig. 1; and

Fig. 3 shows a detail of the showings in Figs. 1 and 2.

Referring to the drawing and particularly to 1936, Serial No. 93,577

-(o1.'2o0 =1cs) contact member a which is bifurcated to secure better current distribution, particularly during the makingand the breaking of the circuit my switch is to control; This stationary bifurcated I contact member is provided with atransversely mounted silverstrip 4 at its heel and is so mounted as .to be somewhat. adjustable on the current carrying terminal 5, which adjustment maybe eir'ecte'd by the bolt 6 fitting loosely into the cur- 'rent carrying terminal 5. The terminal 5 is rigidly secured toan L-shaped insulatingmember l-bythe bolts-and nuts 8. The outer member 9 of the terminal .5 is provided withna suitable.

opening for receiving a binding post or other current transmitting connection.

Switches of the type to which class my invention generally belong'usually have a movable .contact member which movable contact member is energized from a stationary terminal. I provide a stationary terminal 10 having the projection II for connecting it' to the circuit to be controlled. The stationary terminal I0 is rigidly secured to an L-shaped insulating member l2 by means of the bolts and nuts I3. This stationary member has an adjustable current-carrying strip l4, which strip I 4 may be adjusted on the terminal I!) by the bolt 15. It will be-noted that the bolt l5 passes through a rather large opening in the current carrying strip M. This current carrying strip may be of silver or may be of any other metal having a large current carrying capacity. Silver, however, usually is the best metal to use, since it insures a low contact resistance in spite of oxidized contact surfaces.

If the strip I4 is of copper or some other metal that readilyforms an oxide at points where arcs may appear, such strip may be provided with a silver plating at the region where the arcs are to take place or where there may otherwise be heating at the contact regions. The end or region I6 where the heating is'likcly to occur has a rectangular end shape, but may be constructed in the form of a knife edge or arcuate shape to coact with the current carrying strip ll of one of the movable portions of my switch 2. The member I! is adapted to oscillate upon the end I6 as a bearing, and if it is necessary that more than a mere line contact should be maintained, the end I6 may be in the form of an arc coacting with a similar recess in the member or movable strip H at the end I6. In any case, the amount of current that is to be carried f rom the current carrying strip I4 to the movable strip l1 will determine the kind of contact, that is, will deof electrical devices.

termine the shape of the contact at the end I6 between the strips I4 and I1.

In order that the movable strip I! may at all times firmly engage the end I6 of the strip I4, an adjustable spring I8 is rigidly connected to the L-shaped insulating members I and I2 by the bolt I9 rigidly holding the cylindrical lug 20. The spring I8 is firmly connected to the lug 20 on the insulating member I and is similarly connected to a lug 2I threadedly engaging an adjusting stem 22. This adjusting stem 22 passes through an opening in the movable contact strip I! and has an outer disk portion 23 adapted to engage the outer or arcuate ends of the rivets 24 and 25. Since these rivets are arcuate, the friction at this point will be a minimum and will now in no wise add to the difiiculty of operating the movable current carrying strip IT. The pressure with which the movable strip I1 is held against the end I6 will be determined by the adjustment of the spring I8, namely, be determined by th tension to which the spring is subjected by the stem 22. The movable contact carrying strip I1 is also provided with a silver current carrying contact 26 adapted to coact with the silver strip 4 on the heel of the stationary contact member 3.

During normal operation, that is, when all the elements of my switch are in the position shown and the terminals 5 and I are connected to a suitable source of energy and the apparatus to be controlled, current will flow through my switch 2 or circuit interrupter from the terminal through the connection between the terminal 5 and the stationary contact member 3, the silver contacts 4 and 26, the movable current carrying strip H, the end I6 engaging the recess of the movable current carrying strip I1 and the ad justable strip I4 to the terminal I0. From this circuit just traced, it will be apparent that all flexible leads from the terminal I0 to the contact 26 are eliminated and that all of the current during normal operation is carried from the terminal I0 to the movable current carrying strip I! through the bearing end I6.

My switch may, of course, be actuated in any suitable manner as for instance it might be actuated by an electromagnet. However, in the particular showing I have made the operation of the movable current carrying strip I1 is effected through a cam 21 mounted on a shaft 28 which may be operated either manually or by some pilot motor which is to control the operation of one or a considerable number of switches which control the sequence of operation of a plurality This cam 21 coacts with a roller 29 mounted on the bifurcated end of the lever 30. This lever 30 carries the rivets 24 and 25 which coact with the disk portion 23 of the stem 22 and is therefore held in the position shown by the spring I8. As the cam 21 is operated the roller 29 will ride upon the upper or outer circumference of the cam and thereby open the circuit between the stationary terminal 3 and the current carrying strip IT. This interruption of the circuit'takes place, however, in this manner. It usually is desirable not to subject the terminals or contacts as for instance 4 and 26 normally carrying the current that is to be interrupted to the interrupting are. To avoid this I provide the movable arcuate member 3| having a knife edge bearing 32 in the movable strip II. A spring 33 acting upon the arcuate current interrupting member 3I biases this member toward the stationary contact terminal 3 and as the lever 30 rotates in a clockwise direction on the end I6 the arcuate member 3 I, with reference to the lever 30, rotates in a counter-clockwise direction on its knife edge and therefore provides a shunt for ,the contact members 4 and 26 after they have separated so that current passes from strip I! to the bifurcated ends 35 which roll on the stationary terminal 3. The interrupting arc is therefore always carried by the bifurcations 35 of the member 3|, and is thus interrupted in substantially the same manner each time the switch is operated. My switch may, of course, be provided with the conventional arc chute and blowout coils which constitute no part of my invention and therefore havenot been shown. Whether or not elaborate arc quenching means are used will depend on the currents carried by the switch. Arc quenching devices are usually used with my device and especially when called upon to carry currents as high as 50,000 amperes.

Usually, switches of the type I have shown are used for the purpose of controlling a number of circuits so that a plurality of them are mounted to be operable by the cam 21. Fig. 3 illustrates this to some extent by showing a sectional end view of two of the devices and wherein the section of the upper portion is taken on a device such as shown in Fig. 1, in. a plane to illustrate the details of the spring and the.adjustable stem more accurately, whereas the section shown in the lower portion of Fig. 3 illustrates the coaction of the stationary terminal III with the movable current carrying strip IT and the bearing end I6. I

I am, of course, aware that others, particularly after having had the benefit of the teachings of my invention, may devise industrial circuit interrupters that eliminate the use of flexible leads from the movable contact member to its terminal and I therefore do not wish to be limited to the specific showing made in the drawing nor the specific description hereinbefore given, but my disclosure is to be taken in an illustrative sense and the invention is therefore to be limited only by the scope of the claims hereto appended and such prior art as may be pertinent.

I claim as my invention:

1. In an electric switch, in combination, a first stationary current carrying member, an adjustable contact member carried by said first stationary member and normally rigidly secured thereto, a second stationary current carrying member, an adjustable contact member normally rigidly secured to said second current carrying member, said second contact member having a silvered projecting end designed as a bearing, a movable arm having a recess adapted to receive the second named contact member at the silvered bearing and adapted to be rotatable about said bearing, said movable arm being provided with a contact member at the end not engaging said bearing adapted to cooperate with the adjustable contact member on the first stationary current carrying member, and operating means adapted to move said arm on said bearing portion to make and break, as desired, interconnection between the contact member of the movable arm with the adjustable contact member on the first named current carrying member, said operating means comprising a lever of the first class pivoted at said silvered bearing by virtue of which the contact pressure at said silvered bearing increases as the result of movement of said operating means.

2. In an electric switch, in combination, a

first stationary current carrying member, an adjustable contact member carried by said first stationary member and normally rigidly secured thereto, a second stationary current carrying member, an adjustable contact member normally rigidly secured to said second current carrying member, said second contact member having a silvered projecting end designed as a bearing, a movable arm having a recess adapted to receive the second named contact member at the silvered bearing and adapted to be rotatable about said bearing, said movable arm being provided with a contact member at the end not engaging said bearing adapted to cooperate with the adjustable contact member on the first stationary current carrying member, operating means adapted to move said arm on said bearing portion to make and break, as desired, interconnection between the contact member of the movable arm .with the contact member on the first named current carrying member said operating means comprising a lever of the first class pivoted at said silvered bearing by virtue of which the contact pressure at said silvered bearing increases as the result of movement of said operating means, a bearing recess in said movable arm for receiving a pivotally mounted contact member which pivotally mounted contact member is adapted to temporarily maintain interconnection with the first named contact member after the movable arm is being moved by said operating means.

3. In an electric switch having a pair of stationary contact terminals, one of said terminals being silvered and being designed as a bearing, a movable arm having bearing engagement at one of its ends with the said silvered bearing on one ofthe terminals, said movable arm having a contact member at the other end, that is, the end remote from the end engaging the bearing,

a spring, means for adjusting the tension of the spring, said adjusting means engagingthe arm and being disposed to bias the arm against the other of the terminals and against the bearing of the first terminal by a force determined by the adjustment of the adjusting means of the spring, and means comprising a lever of the first class pivoted at said silvered bearing for operating the arm in opposition to the biasing effect of the spring to thus pivotally move the arm on the said bearing with increased bearing contact pressure on one of said contact terminals and away from the other contact terminal.

4. In an electric switch having a pair of stationary contact terminals, one of said terminals being designed as a bearing, a movable arm having bearing engagement with the bearing end of one of the terminals, said movable arm having a contact member at the end remote from the end engaging the bearing adapted to engage the other contact terminal, a tension spring, means for adjusting the tension of the spring, said adjusting means engaging the arm and disposed to bias the arm against the other of the terminals and against the bearing of the first terminal by a force determined by the adjustment of the adjusting means of the spring, operating means for pivotally operating the armin opposition to the biasing effect of the spring to thus pivotally move the arm on the bearing end of one of the contact terminals and away from the other contact terminal, said arm being provided with a straight recess disposed transversely of the arm, a bifurcated contact member having an edge at one end thereof engaging the base of the recess as a hearing, and a spring for biasing the bifurcated member toward the other contact terminal whereby said contact terminals are not immediately disconnected during the movement of said arm on the bearing surface of the first contact terminal,

to interrupt the interconnection between the ter- 'minals.

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