US2162642A - Electric switch - Google Patents

Description

C. A. SCHAEFER June 13,1939.

ELEQTRIC SWITCH Filed Nov. 21, 1936 2 Sheets-Sheet '1 INVENTOR CarZ l7 56%46762': 57 IZYTORNEY June 13, 1939. c SCHAEFER 2,162,642

ELECTRIC SWITCH Filed Nov. 21, 1936 2 Sheets-Sheet 2 IN VENTOR 6'47"] /9.' jbfiaefei? A TTORNE Y Patented June 13, 1939 UNITED STATES PATENT OFFICE 2,162,642 ELECTRIC swrrcn tion of Michigan Application November 21, 1936, Serial No. 112,089

9 Claims.

This invention relates to electric switches and more particularly to electric switches automatically operable in response to changes in an external condition.

One object of the present invention is to provide an improved means for manually opening the circuit through an automatic switch.

Another object of the invention is to provide an automatic electric switch having an overload relay with improved means for preventing disabling of said relay while current flows through the switch.

Another object of the invention is to provide an electric switch automatically operable in response to an external condition and having an overload relay with auxiliary contacts openable upon resetting of the relay to break the circuit through the switch.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and the appended drawings illustrating. certain preferred embodiments of the invention in which:

Figure 1 is a front elevational view of the device according to the present invention.

Figure 2 is an enlarged view similar to Figure 1 with the cover removed and parts broken away to show internal parts.

Figure 3 is a horizontal sectional view on the line III-III of Figure 2.

Figure 4 is a detailed vertical sectional view on the line IVIV of Figure 3.

Figure 5 is a view similar to Figure 4 with the parts in another position.

Figure 6 is a detailed sectional view on the line VIVI of Figure 4.

Figure 7 is a vertical sectional view on spaced planes, the upper portion being a central longitudinal section and the lower portion thereof being a longitudinal section in a plane displaced toward the front of the switch.

The switch according to the present invention constitutes an improvement upon and a variation in that disclosed in applicants co-pending application No. 77,723. filed May 4, 1936 for Electric switches and comprises an insulating en-- closure i having a front cover 2 carrying a manual operator 3 pivotally mounted thereon. Upon a stationary. bracket 4 within the enclosure are pivotallymounted, as at 20, a pair of contact arms 5 and 6 having limited relative movement. with the arm 5 formed of conducting material and carrying a movable contact I, and with the arm 5 formed of magnetic material and cooperating and break action of the switch arms. A stationary contact 9 is mounted on a flexible arm II which bears against a cam member l2 rotatable to vary the position of the stationary contact 9 and hence the differential of operation of the switch. A light tension spring Ill is connected to the arm 6 and biases the contact armstoward engaged position. The arm 5 is provided adjacent its lower portion with a pin I3 engageable by an insulating portion H rigid with a pivoted lever i5 to move the arms to disengaged position. The arm 5 has a limited movement relative to the arm 6 between the adjacent surface of the arm 6 and the back surface of the contact I. In the closed position the force exerted upon the arm 5 by the magnet 8 increases the pressure between the contacts 1 and 9 by the bearing of arm 5 against the contact I. As the'insulating portion l4 engages the pin i3 in its downward movement it will eflect initial movement of the arm 5 without moving the arm 5 which is maintained in place through the tension spring I0 until it is engaged by the arm 5. The force necessary to move the arm 5 against the attraction of the magnet 6 decreases rapidly with the air gap between the arm and the magnet so that the arm 5 will tend to move rapidly after the initial overcoming of the magnetic force at the closest position of the arm. Hence it will engage the arm 5 while moving and will efiect relatively quick break of the movable contact 1 from the stationary contact 9. Similarly, upon closing, as the insulating portion I4 movesupward1y the arms 5 and 6 will move toward closed position under the bias of the'spring Ill. As the arm 5 approaches the pole faces of the magnet 8 the magnetic force exerted thereon increases rapidly and effects the final closing movement of the movable contact I rapidly. Hence quick make and quick break operation of the movable contact l is attained. The rotation of the cam I! which varies the position of the stationary contact 9 will serve to vary the air gap between the pole faces of the magnet 8 and the magnetic arm 5 since the position of the arm 5 is determined by its engagement with the back face of the movable contact 7. This variation in air gap varies the initial force necessary to move the arm 5 toward disengaged position and hence varies the differential of operation of the switch. For moving the lever l5 there is provided a pressure responsive unit comprising a bellows chamber it having a bellows ll disposed therein and connected to an operating pin II which bears at its upperend against the under side of the lever I5.

A compression spring l9 adjustable by means of a nut 2i may be provided .to vary the limits of the range of operation of the device. Opposing movement of the lever i5 by the pressure unit is acompression spring 22 bearing against the upper surface of the lever l5 and engaged at its. upper end by a cupped nut 23 threaded upon an adjusting screw 24 for varying the range or operation of the switch.

The arm 5 is provided with an extension 25 engageable by a striker 26 for movingthe movable contact to its separated position in response to a current overload. The striker 26 is mqunted on a sliding member 27 biased to striking position by a spring 23. The back portion of the slide 27 is provided with a latch engageable with a ratchet wheel 29 to maintain the slide in retracted posi-' tion. The ratchet wheel 29 is disposed on a shaft mounted within a'solder pot cylinder 3| containing a metal alloy melting at a definite predetermined temperature in response to the heating effect of a resistor coil 32 thereabout. All of these related parts are supported upon an insulating base 33 which is'r'eadily demountable from the center to provide, snapoperation of the manually 'movable parts. At the back of the base 33 the shaft 34 is connected to an insulating member 4! having a projecting portion 42 carrying a conducting bri ng contact member 43. Rigidly mounted closely adjacent to the stationary magnet 8 is an insulating plate 44 preferably of a high resisting arc material. Mounted on this plate are a pair of flexible contact arms 45 and 46 carrying contact surfaces adjacent to their free ends adapted to be bridged by the conducting portion-43 when in the closed circuit position. The contact arm 45 is mounted on a me tallic" bracket 41 having a spaced surface 43 adapted to be engaged-by a conducting portion 43 embracing a portion of the base 33 and con :tacting an end of heater coil 32. The contact arm 45 is rigidly secured at one end to a conducting plate 5| which is in turn-connected by means of a stud 52 toa supporting bracket '53 leading to the main stationary contact supporting arm ll.

, -Between the supported ends of the contact arms 45 and-45 "is preferably disposed an-insulating block 54 havingan arc splitting tip 55 as shown,

Rigid with the portion 42 there is provided an insulated portion 55 disposable between the contact portions 'ofthe arms 45 and 45 as the circuit is broken and cooperating with the tip 55 in crating contact surfaces.

suppressing any are mounted a'contact terminal 51 connected by means of plate 55"to one end of the heater coil.

32 and on the bracket 4 is mounteda second terminal 53. .The bracket 4 is connectedto switch "arm 5 by means of a flexible leadil- II, bracket 4, and terminal".

drawn between the coop-. Upon'the base 33 is.

The operation of the switch will now be described: In the normal operation of the switch the pressure within the bellows chamber it will cause the lever l5 to move upwardly and downwardly depending upon the direction of the change and the position of the switch. With the contacts in closed circuit position a decrease in pressure within the bellows chamber 86 will cause the lever, 95 to move downwardly until the end moves the contacts to the disengaged position. Should the pressure within the bellows chamber thereafter increase the lever 65 will be moved upwardly, thus moving the insulating portion it out .of engagement with pin l3 and permitting the contact arms to be moved into engaged position under the bias of the spring iii. Should it be desired to manually open the circuit through the switch the operator 3 is simply moved in a clockwise direction to the ofi position whereupon the bridging contact element 43 will be moved out of engagement with the contact surfaces of the arms 45 and 65', thus interrupting the circuit through the switch at this point. Should an overload occur through the switch the metal alloy within the solder pot cylinder 3i will become melted due to the heat generated by the coil 32 thus permitting the ratchet wheel 29 to turn. The slide 21 will'then be moved toward the right under. the bias of spring 28 and the striker 26 will engage extension 25 on the arm 5.and will move the movable contact i to-disengaged position. To reset the overload relay after an automatic operation the manual-operator 3 is rotated to the ofi position whereupon the'arm engagesslide 21 and moves it back into position where it is again latched by the ratchet wheel-23 'providing'the solder metal has cooled sufiiciently to prevent rotation of the wheel. It can readily "be seen that the bridging contact element. 63 will have been moved to disengaged position during this operation so that, while the overload relayis in inoperative position due to resetting, the circuit through the switch is broken at the auxiliary contacts and it is impossible to disablethe overload relay insuch a manner as to permit overload currents to pass through the switch withoutprotection.

While'ertain preferred embodiments [of the invention have been specifically disclosed, it is understood that the invention is not limited thereto' as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest .possible interpretatlon within the terms of the following claims.

What is claimed is:

1. In an electric switch, separable contacts,

normally operable means responsive to an exterior condition for separating said contacts, ab-

normal means responsive to current overload for separating said contacts, auxiliary contacts in circuit with said switch, and means for opening said auxiliary contacts while resetting said abnormal means.

, 2. In an electric switch, stationary and movable contacts, mechanism responsive to an exterior condition for moving said movable contact to engaged and disengaged positions,.means responsive to current'overload through the switch for moving said movable contact to disengaged position, auxiliary contacts in series circuit with said first-mentioned contacts, means for resetting said ratingsaid auxiliary contacts when said resetting means is operated. '3. In an electric switch, stationary and movcurrent responsive means, and means for sepaable contact to be moved to engaged position by said mechanism in response to the exterior condition.

4. In an electric switch, relatively movable contacts, mechanism responsive to an exterior con dition for normally effecting such relative movement, means responsive to current overload for eflecting separation of said contacts regardless of said condition, manual means for resetting said current responsive means, auxiliary contacts in series circuit with said first mentioned contacts, and means effecting separation of said auxiliary contacts in response to movement of said manual means to resetting position.

5. In an electric switch, a stationary contact, a movable contact cooperating therewith, means biasing said movable contact to engaged position, means responsive to an external condition for moving said movable contact to disengaged position, means responsive to current overload for moving said movable contact to disengaged position regardless of said condition, manual means for resetting said current responsive means, auxiliary contacts in series circuit withsaid stationary and movable contacts, and means effecting separation 01' said auxiliary contacts in response to movement of said manual means to resetting position.

8.1n an electric switch, switching contacts, mechanism responsive to an external condition for operating said contacts, means responsive to current overload for effecting separation of said contlctna pair of resilient contact arms for said current responsive means connected to move said bridging contact to disengaged position when operated to resetting position.

'7. In an electric switch, a pair of superposed,

resilient contact arms carrying opposed contact surfaces adjacent to their free ends, a stationary insulating member between said arms adjacent to their fixed ends and having a wedge-shaped portion extending toward said contact surfaces, a bridging contact element movable between said contact surfaces, and means for moving said contact element to perform the switching operation.

8. In an electric switch, a pair of superposed contact arms carrying opposed contact surfaces adjacent to their free ends, a bridging contact element swingable in a plane at right angles to said contact surfaces into a position between and in engagement with said contact surfaces, an insulating barrier connected to said contact element and movable therewith, said barrier being disposed between but out of engagement with said contact surfaces when said contact element is in disengaged position, and means for oscillating said contact element to perform the switch-. ing operation.

9. In an electric switch, a pair of superposed, resilient contact arms carrying opposed contact surfaces adjacent to their free ends, insulating surfaces disposed on opposite sides of said arms, an insulating member between said arms adjacent to their fixed ends and having a wedgeshaped portion extending toward said contact surfaces, a bridging contact element movable into and out of engagement with said contact surfaces to effect the switching p ration and an. insulating portion disposed between said arms and movable with said bridging contact into a position between said contact surfaces.

CARL A. scrum.

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