US3711800A

US3711800A - Electrical relay

Info

Publication number: US3711800A
Application number: US00165170A
Authority: US
Inventors: H Clinton
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-07-22
Filing date: 1971-07-22
Publication date: 1973-01-16
Anticipated expiration: 1990-01-16

Abstract

An electrical relay includes a resilient, conductive contact arm mounted to the base or frame of the relay by means of a pivotal hinge which permits the contact arm to be pivoted between alternate contact positions against two electrically isolated contacts also mounted on the base. The contact arm is actuated between the two contacts by means of an electrical solenoid. A spring incorporated within the pivotal hinge urges the contact arm against one of the contacts and the electrical solenoid actuates the arm against the other of the contacts in opposition to the spring. The flexing characteristics of the contact arm produce slight wiping motions against each of the fixed contacts to insure that a low resistance junction is made between each of the contacts and the arm.

Description

United States Patent m1 Clinton j 5] Jan. 16, 1973 [54] ELECTRICAL RELAY [57] ABSTRACT I Henry Clinton, walnut Slfeei- An electrical relay includes a resilient. conductive RFD lvoryton, Conn 06104 contact arm mounted to the base or frame of the relay [22] Filed: July 22, 1971 by means of a pivotal hinge which permits the contact Appl. No.: 165,170

Primary Examiner-Harold Broome Att0rney-Rogcr B. McCormick et al.

arm to be pivoted between alternate contact positions against two electrically isolated contacts also mounted on the .base. The contact arm is actuated between the two contacts by means of an electrical solenoid. A spring incorporated within the pivotal hinge urges the contact arm against one of the contacts and the electrical solenoid actuates the arm against the other of the contacts in opposition to the spring. The flexing characteristics of the contact arm produce slight wiping motions against each of the fixed contacts to insure that a low resistance junction is made between each of the contacts and the arm.

PATENTEDJAH 1 6 I975 FIG.3

INVENTOIL HENRY H.CL|HTON J TORNEYS' ELECTRICAL RELAY BACKGROUND OF THE INVENTION The present invention relates to electrical relays and, more particularly, is concerned with relays having large throws between fixed contacts such as found in many high voltage relays.

Relays which are designed to operate at high voltages, that is, voltages in the order of several thousand volts and more, employ several different means for insulating the contacts against arching or discharge currents when the high voltages are applied to the contacts. In some relays, the contacts are hermetically sealed in an evacuated glass envelope having an external operating coil. The cost of such relays is high due to the complexity of the evacuated construction and the high level dc. power operating components external of the envelope. The contacts in such systems are subject to welding and low ohmic resistances between the contacts are not fostered because wiping motions between the contacts are necessarily limited by the confining geometry of the envelope.

In relays having air-insulated contacts, the spacing must be large for high voltage isolation and, correspondingly, large excursions or throws of the moving contact member are required between the contacts. Because of the relatively short throw provided by electromagnetic actuators, a motion multiplying linkage is frequently employed between the actuator and the movable contact member. Such linkages generate large frictional forces which must be overcome by the available operating power of the actuators and shorten the relay life through mechanical wear. Incorporating an additional element, such as the multiplying linkage in the relay, reduces the overall reliability from that of the system without such a linkage because of the tendency of the linkage to bind or stick. Furthermore, the reliability of the relay degenerates faster during the operational life of the relay because the throw of the solenoid usually terminates abruptly and produces a pounding action at the contacts which must be absorbed through the linkage.

Smaller spacing between high voltage contacts is often permitted by submersing the contacts in an oil bath. A disadvantage in such systems is that the accumulation of debris attracted to the electric field between the contacts from the oil and other components contributes to anelectrical breakdown and arching between the contacts. The increased accumulation in the field causes contact misses and more arching so that once the debris is generated, its accumulation accelerates. In relays where there is more than one set of contacts sharing the same oil bath for reasons of economy, the failure of one set of contacts contributes to the accumulation of debris throughout the bath and the failure of the other contacts.

It is a general object of the present invention to disclose an improved electrical relay suitable for use with high voltages and having a relatively large throw between contacts to permit operation without the disadvantages associated with electrical relays of the prior art.

SUMMARY OF THE INVENTION The present invention resides in an electrical relay having a base on which first and second electrical contacts having spaced contact faces are mounted electrically isolated from one another. A pivotal hinge, as opposed to a flexural hinge, having a first element mounted to the base and a second element pivotally mounted to the first provides hinging movement relative to the base and the electrical contacts. A resilient contact arm is connected to the second element of the pivotal hinge so that the arm is supported for pivotal movement between alternate contact positions against the respective contact faces of the electrical contacts. Electrical actuating means moves the resilient contact arm to the one contact position against the contact face of the first contact and resilient means, such as a biasing spring incorporated in the pivotal hinge, is provided to move the contact arm in the opposite direction toward the contact position against the contact face of the second contact. The principal advantages gained by utilizing both the resilient contact arm and a pivotal hinge to move the contact arm between the spaced contact faces, are that large scale flexing of the contact arm and the associated fatigue is prevented and a fairly constant biasing force is applied to the contact arm by a spring element other than the arm itself.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 isa perspective view of an electrical relay embodying the present invention in an installation suitable for mounting a plurality of the relays in side-by-side relationship.

FIG. 2 is a side elevation view of the electrical relay shown in FIG. 1 with the contact arm in one of the alternate contact positions.

FIG. 3 is a side elevation view of the electrical relay with the contact arm in the other of the alternate contact positions.

FIG. 4 is a detailed sectional view of the pivotal hinge which mounts the contact arm to the base of the relay.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the electrical relay embodying the present invention in an installation suitable for mounting a plurality of the relays in sideby-side relationship. The electrical relay, generally designated 10, is particularly suited to such multiple unit installations which permit r'nany of the elements of the adjacent relays to be interconnected in unitized construction and facilitate simplified and more economical manufacturing. The multiple unit installation has found utility in cable testing apparatus and permits rapid and reliable inspection of multi-conductor cables. Of course, the invention is embodied in a single electrical relay and can be utilized as an isolated unit if desired.

As shown in FIGS. 1, 2 and 3, the relay 10 has a frame or base plate 12 to which the remaining components are connected. The base plate 12 as shown in FIG. 1 is a plate having a plurality of apertures 14 for a plurality of electrical solenoids 16. For clarity, only one solenoid 16 adjacent the end of plate 12 is shown mounted on a plate bracket; however, it will be understood that a plurality of such solenoids can be placed side-by-side on the bracket 18 at each aperture 14. As seen most clearly in FIGS. 2 and 3, the apertures 14 permit the solenoid plunger or armature 20 to move to the right through the base plate 12 when the solenoid 16 is energized through the

solenoid terminals

22 and 24 supported in an insulator 26.

The solenoid 16 is preferably a push-type, electromagnetic, a.c. operated solenoid having the armature 20 supported by internal bearings. When the solenoid is energized, the armature 20 is pulled from the left-hand limit position shown in FIG. 2 to the righthand limit position shown in FIG. 3. At the left-hand limit position with a major portion of the armature located on the periphery of the magnetic field within the solenoid, large a.c. energizing currents can be applied to the solenoid to generate large actuating forces. When the solenoid is energized and the armature moves through a relatively long stroke to the right-hand limit position largely centered within the magnetic field, a much smaller current is drawn and, therefore, heat generation is minimized while the relay is held energized.

An electrically non-conductive push rod 30 is connected to the end of the armature 20 and engages the midsection of a resilient, conductive contact arm 32. The contact arm 32 is mounted in a pivotal hinge 34 supported on a non-conductive base block 36 connected to the base plate 12. The push rod 30 when actuated by the solenoid armature 20 moves at a right angle to the contact arm 32 and causes the arm to pivot in he hinge 34 and move the double-faced contact button 38 at the upper end of the arm between alternate contact positions against the spaced contact faces of the

electrical contacts

40 and 42. The

contacts

40 and 42 are mounted respectively in

bus bars

44 and 46 and the bus bars are in turn mounted in electrically isolated relationship to the base plate 12 by means of the insulators or

standoffs

48 and 50 and the screws 52 and 54.

The details of the pivotal hinge 34 are shown in the sectional view of FIG. 4. The hinge 34 is a pivotal hinge as opposed to a flexural hinge and permits the contact arm 32 to be pivoted relative to the base block 36 and the plate 12 between the two

contacts

40 and 42 without the strain and fatigue associated with a purely flexural hinge. The pivotal hinge 34 is comprised principally of a mounting member 60, a pivotal member 62' and a hinge pin 64. Both

members

60 and 62 have a channel configuration; however, other configurations might also be employed. The mounting member 60 is mounted to the base block 36 by means of a hollow terminal 70 which also serves as an electrical jack connecting with the contact arm 32. The contact arm 32 is riveted to the pivotal member 62 and a low resistance electrical connection with the terminal 70 is provided by means of a conductive strap 72 and a terminal lug 74.

A coil spring 80 is mounted on the hinge pin 64 and biases the pivotal member 62 relative to the member 60 so that the contact arm 32 is moved toward the one alternate contact position against the contact 40. The spring 80 also returns the solenoid armature 20 to the left-hand limit position shown in FIG. 2 when the solenoid 16 is de-energized.

There are several advantages gained from construction of the electrical relay as shown and described above. The pivotal hinge 34 permits the contact arm 32 to be actuated by the solenoid 16 over a relatively large throw between the

spaced contacts

40 and 42 without the attendant fatigue and failure of a flexural hinge which can foreshorten the operational life of the relay. In addition, the coil spring 80 provides a more uniform biasing force throughout the throw of the contact arm 32 so that the solenoid 16 does not operate against a sharply increasing biasing force as the arm 32 is moved from contact 40 to contact 42. The biasing force at the extreme left-hand position of the contact arm 32 shown which is at a right angle to the midsection of the flexible arm 32 and thereby transmit maximum force to the arm to achieve maximum contact pressure between the faces of the contact button 36 and contact 42. Furthermore, due to the resilient flexing of the contact arm 32 and the engagement of the push rod 30 with the midsection of the arm, a wiping motion between the contact faces is produced as the solenoid urges the arm into a slightly bowed configuration shown in FIG. 3. The wiping motion between the contact faces improves the electrical association of the contacts and aids in producing a low resistance current path between the bus 46 and the terminal 70. When the solenoid 16 is deactivated and the contact arm 32 returns to the positionshown in FIG. 2, a wiping motion is again produced between the contacts as the spring 80 urges the contact arm 32 into the bowed position shown. A low resistance current path between the bus 44 and the terminal is therefore created. The spread condition of the

contacts

40 and 42, the elongated resilient contact arm 32 and the spring-biased hinge 34 all contribute to the improved wiping action at the contact surfaces and the reduction of the ohmic resistance between the contacts.

The large operating forces produced by the a.c. solenoid contribute to the rapid switching of the contact arm between the

contacts

40 and 42; however, the flexing of the arm 32 between therod 30 and contact 26 minimizes the shock loading of the contact 42 and bus bar 46. The reduction of the shock loading and the elimination of any motion-amplifying linkage between the solenoid and the contacts improves the operational life of the relay.

A relatively large spacing between the

contacts

40 and 42 makes the relay 10 ideal for use with high voltages, that is, voltages of several thousand volts or more. The use of the insulating

standoffs

48 and 50 and the non-conductive block 36 also permit the relay to be used for the measurements of extremely high resistance by additionally connecting a guard circuit to the base plate 12 from a measuring device to eliminate leakage currents in or on the insulating components.

The relays can be readily installed in multiple units on a single base plate 12 as indicated in FIG. 1 and, in addition to the base plate, other components such as the bus bars 44 and 46 can be shared by the relays to provide simplicity and economy in manufacture.

It will thus be seen that an electrical relay has been described which has high contact pressures and a large degree of contact wiping resulting in a high degree of reliability in operation. Furthermore, the design assures simplicity and economy in manufacture and at the same time is oriented to preserving along operational lifetime with low maintenance.

I claim:

1. An electrical relay comprising: a base; first and second electrical contacts having spaced contact faces mounted to the base and electrically isolated from each other; a pivotal hinge having a first element mounted to the base and a second element pivotally mounted to the first for hinging movement relative to the base and the electrical contacts; a resilient contact arm connected to the second element of the pivotal hinge and supported by the second element for pivotal movement between alternate contact positions against the respective contact faces of the electrical contacts, the resilience of the arm and the hinging movement of the hinge being cooperative to permit the arm at the alternate contact positions to flex into bowed positions between the second element of the hinge and the electrical contacts and to thereby produce wiping motions between the contact arm and the faces of the contacts; and electrical actuating means-for moving the resilient contact arm to one contact position against the contact face of the first electrical contact.

2. An electrical relay as defined in claim 1 further including resilient means for biasing the resilient contact arm toward the other contact position against the contact face of the second electrical contact.

3. An electrical relay as defined in claim 2 wherein the resilient means comprises a coil spring mounted to the pivotal hinge and operating against the first and second elements.

4. An electrical relay as defined in claim 1 wherein: the resilient contact arm is electrically conductive and is connected at one end to the second hinge element and supports contact surfaces at the other end which mate with the contact faces of the first and second contacts', and the electrical actuating means comprises an electrical solenoid having an armature and a movable push rod connected to-the armature and engaging the resilient contact arm at a section between the ends of the arm.

Y 5. An electrical relay as defined in claim 4 wherein the electrical actuating means is mounted to the base to provide a push rod movement which is substantially at a right angle to the midsection of the resilient arm at each of the alternate contact positions.

6. An electrical relay as defined in claim 5 wherein the movable push rod is electrically non-conductive.

Claims

1. An electrical relay comprising: a base; first and second electrical contacts having spaced contact faces mounted to the base and electrically isolated from each other; a pivotal hinge having a first element mounted to the base and a second element pivotally mounted to the first for hinging movement relative to the base and the electrical contacts; a resilient contact arm connected to the second element of the pivotal hinge and supported by the second element for pivotal movement between alternate contact positions against the respective contact faces of the electrical contacts, the resilience of the arm and the hinging movement of the hinge being cooperative to permit the arm at the alternate contact positions to flex into bowed positions between the second element of the hinge and the electrical contacts and to thereby produce wiping motions between the contact arm and the faces of the contacts; and electrical actuating means for moving the resilient contact arm to one contact position against the contact face of the first electrical contact.

4. An electrical relay as defined in claim 1 wherein: the resilient contact arm is electrically conductive and is connected at one end to the second hinge element and supports contact surfaces at the other end which mate with the contact faces of the first and second contacts; and the electrical actuating means comprises an electrical solenoid having an armature and a movable push rod connected to the armature and engaging the resilient contact arm at a section between the ends of the arm.

5. An electrical relay as defined in claim 4 wherein the electrical actuating means is mounted to the base to provide a push rod movement which is substantially at a right angle to the midsection of the resilient arm at each of the alternate contact positions.