US2575699A - Electrical contactor - Google Patents

Description

2 SHEETS-SHEET 1 Filed Jan. 22, 1947 Insu/af/an INVENTORS Pau/ 6. flab/n and Max M 'fixman.

WITNESSES: 7% 7260. A

BY fjmw ATTORNEY Nov. 20, 1951 R ADAMS ETAL 2,575,699

ELECTRICAL CONTACTOR Filed Jan. 22, 1947 2 SHEETS-SHEET 2 INVENTORS WITNESSES:

W Pau/ G fiaams and I I MaxM/ Xma/w. I 1,

ATTORNEY Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE ELECTRICAL CONTACTOR Application January 22, 1947, Serial No. 723,536

1 Claim.

This invention relates to electrical contact devices and it has particular relation to electrical switches suitable for interrupting briefly and repetitively electrical circuits.

In certain applications, a switch is desired which normally maintains a circuit closed but which can be opened briefly for the purpose of generating impulses in the system. For example, in one well known system for totalizing the energy supplied to a plurality of electrical circuits, each circuit is provided with a contact device operated by a watthour meter. All of the contact devices are connected in series with an impulse operated meter. The impulse operated meter is operated, or notched, for each opening of a contact device. In order to minimize errors introduced by simultaneous opening of two or more contact devices, it is desirable that the opening of each contact device he as brief as possible. Furthermore, it is desirable that the contact devices impose a substantially uniform load on each of the watthour meters.

In accordance with the invention, a snapacting contact device is provided which is normally closed, but which may be actuated with a snap-action for the purpose of briefly opening a circuit associated therewith. The snap-acting device requires a force which varies over the operating cycle of the device, and compensating means are provided for the purpose of maintaining the load on a watthour meter associated with the contact device substantially uniform. In a preferred embodiment of the invention, a pair of snap-acting devices are employed, each requiring a force which varies over the operating cycle of the associated contact device. The contact devices are disposed for operation from a common operating member in such a manner that the respective forces required therefor are displaced in phase. For this reason, the resultant force required for the common operating memher is reasonably uniform.

It is, therefore, an object of the invention to provide an improved contact device suitable for briefly opening a circuit associated therewith.

It is a further object of the invention to provide a snap-acting contact device which may be operated periodically.

It is an additional object of the invention to provide a snap-acting switch which is compensated to require a substantially uniform operating force.

It is also an object of the invention to provide a pair of snap-acting contact devices disposed for-operation from a common'operating member wherein the contact devices are disposed to apply a substantially constant load on the operating member.

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view in topplan of a device embodying the invention;

Fig. 2 is a view in side elevation of the device illustrated in Fig. 1;

Fig. 3 is a view in front elevation, with parts broken away of the device illustrated in Fig. 1;

Fig. 4 is a schematic view of a system embodying the invention; and

Figs. 5 to 8, inclusive, are views in top plan illustrating various positions of a portion of the device illustrated in Fig. 1.

Referring to the drawings, Fig. 1 shows a contact making device wherein a plurality of contact strips are secured to an insulating member I which may be constructed of a suitable insulation material, such as a phenolic resin. The insulating member may be secured to a supporting plate, or base 3, in any suitable manner, as by machine screws 5 (see Figs. 2 and 3). As shown more clearly in Figs. 2 and 3, four contact strips 1, 9, H and I3 are secured to one face of the insulating member I by means of screws l5. Also, four additional contact strips [1, l9, 2| and 23 are secured to the opposite face of the insulating member by means of machine screws 25.

In order to establish contact between pairs of contact strips, an electro-conductive pin 21 is disposed for movement between pairs of contact strips. This contact pin conveniently may be mounted on a lever 29 constructed of an insulation material, such as a phenolic resin. The lever 29 is mounted for rotation about a shaft 31 which is suitably secured to the base 3. In the position of the parts illustrated in Figs. 1' and 3, the pin 21 engages and electrically connects the contact strips I and 9. However, the lever 29 may be operated in a counterclockwise direction as viewed in Fig. 1 to move the pin 21 into engagement with the contact strips l1 and IQ for the purpose of electrically connecting such strips. In a somewhat similar manner, the contact pin 33 may be secured to a lever 35 for rotation about the shaft 3|. The pin 33 and the lever 35 are similar in construction to the pin 2! and the lever 29, but the pin 33 is disposed for operation into engagement with the contact strips ll and I3 or the contact strips 2| and 23 in response to rotation of the lever 35 about the shaft 3 l Conveniently, the levers 28 and may have bushings 29a and 35a, respectively, associated therewith for reception of the shaft 3|. The shaft 31 projects from a post 31 which is secured'to the base 3.

Operating forces may be applied to the levers 29 and 35jthrough pins 29b and 3% which are-secured respectively to the levers 29 and 35.

Actuation of the lever 29 with a snap action may be effected by means of a link 39 which is mounted for rotation about a shaft ll. 2 The shaft ll projects from a post 43 which is seecured to the base 3. A second link dc-maysimilarly be mounted for rotation about-the shaft 4! for operating the lever 35; Asisho'wn' most clearly in Fig. 2, the links 39 and d5, respectively, may be provided withbushings 39a and 45a, which, in turn, receive the shaft 45. Pins 39b and 451) are secured respectively to the free ends of the links 35 and 55.

' As shown most clearly in Fig. 1, a U -shaped spring 4'! has its ends engaging the pins 39?) and 29b. Conveniently, one end of the spring t? may be coiled in a groove 390 (Fig. 2) formed inthe pin 39b to prevent displacement of the spring ll from the pin. In a similar manner, a U-shaped spring 69 has its ends associated with the pins 45b and 3512. These springs are always under a spring stress which tends to force apart the ends of each of the springs.

Referring to Fig. 1, it will be observed that the spring 41 urges the lever 29 in a clockwise directional-bout the shaft 3! to maintain the pin 27 in engagement with the strip 1. As the link 39 is rotated in a counterclockwise direction about the shaft 1!, the line of action of the spring 4'! rotates about the pin, 29b until it' crosses the shaft 3!. Th'ereup'on, the spring urges the lever 29in a counterclockwise direction to carry the pin-27 rapidly from engagement with the strip 1 into engagement with the strip 32. If the lever 29 is returned to the position illustrated in Fig; 1 by rotation'of the link 59 in a clockwise direction about the shaft ii,

the line of action of the spring ll rotates about the pin 29?) in a counterclockwise direction until 1 it recrosses the shaft 38-. In response to such rotation of the line of action of the spring, the lever 25 is returned. rapidly from "engagement with the strip ll into engagement with the strip '7. It should be noted that each of the movements of"the-lever--29 is effected with a snap action. Operation of the lever 15 similarly results in snap actions of the lever 35.

In order to'oscillate the link 39' repetitively for the purpose of producing snap actions of the associated. lever '29, the link'is-provided with a slot/5i for reception of a circular cam 53. This cam is secured to a gear 55'for rotation as a unit abouta shaft 57. Since the cam 53 is eccentric with respect to the shaft 57, it follows that rotation of the gear 55 results in oscillation of the link '39 about the shaft lia The shaft 5'5 may be -secured to apost 53 which, in turn,-is 'secured to the base 3.

'In a similar manner, the link 45 maybe pro-- vided with a slot 6! for-reception of a circular cam 63; The cam 53 is'secured to the gear 55; but it willbe noted thatthe cams 53 and Go are on opposite faces of the gear 55.

Rotation of the gear 55' may beeffected bycoupling the-gear to anysuitablemotive source r 55. For the purpose of discussion,-itwi1l be; assumed thatthe motive-source 55 of Fig. 1 rep 4 This armature disc is mounted on a shaft 61 which also carries a pinion 69. The pinion 69 is coupled to the gear through an idler gear H which is mounted for rotation about a shaft 13 suitably secured to the base 3. The unit comprising the meter and the associated contact making device-is designated by :the reference character M.

It is desirable that a load applied to the watt- ;hour meter be substantially uniform. By reference to Fig. 1, it will be observed that the spring A! acting through the link 39 and the cam 53 applies aload to the gear 55 which varies substantially as a function of the rotation of the cam'about the shaft 57. At the instant that the link 39 changes its direction of oscillation aboutthe shaft Al, the load applied by the spring All to the gear 55 is substantially zero. Between such instances, the load increases to a peak value and then decreases.

For the purpose of compensating the varying force applied by'the spring 41' to the' watthour meter, the earns 53' and 63 are angularly spaced about the shaft 57.

placed from each other by an. angle 0f90".

mum load to the gear 55-,the spring 49 is ap plying substantially a -minimumload to the Consequently,.-theresultant load on samegear. the gear 55 is reasonably uniform.

It is believed that the operation of the invention may be discussed with reference to Fig. land the succeeding figures. Asshown in Fig.

4, the unit M of Fig. 1 is associated with a totalizing impulse meter T and a battery 13; In addition, Fig. 4 shows a secondunit M which is similar to theunit The re istrations of the units M and-M are-tobe transniitted to the meter '1 for totalization. 'I'his'totalizing meter may include a solenoid-Blhaving an armature associated with a pawl 83 and a ratchet Wheel 85.

M and M 21 of the unit M, pin 33' ofthe unit M; pin 2'! of the unit M and the solenoid Sl iii-series. Consequently, any movement of the phis which interrupts the series circuit results in .a notching operation of the totalizing impulse-meter T. As.

the armaturedisc of the unit M rotates, the pin 21 is moved from: engagement with the strips -l' and 9 into engagement with the strips 1? and!!! to produce a notching-operation-of the meter T. It should be observed thatthe-pin zl.moves with:

a snap; action andthatithe timeduring which the series: circuit is openedis determined byzthespacing. of the contact strips by the-inertias'offi the parts and by the force exertedby the associated spring-,-4'l- '(Fig. 1).

circuit is interrupted may, be made extremely small. It will be understood-that theztotalizing. impulse meter T is designed to operate in re-.- sponse to extremely brief interruptions 'in-the supply of current to the=solenoid 8|. In a'somewhat, similar manner,-. movement ,of the pin; .33 resents the armature disc of a watthour meter... from engagement-with thecontact-strips-Z band.-

Although' the exact angle may vary over an appreciable range, in the specific embodiment of Fig; 1, the cams are dis- This means that when thespring ll applies a maxi-- The solenoid normally is energized, but is briefly deenergized by the operation of the units 1 For each deenergization of the sole noid, the ratchet wheel 854s notched forward By; proper design of the parts, the period during whichthe serics- 23 into engagement with the contact strips H and I3 results in a brief interruption of the series circuit. It will be noted that the contacts H a d 3 are connected in parallel with the contacts 2| and 23 and that the contacts and 9 are connected in parallel with the contacts and IQ of the device M. For this reason, four interruptions of the series circuit are obtained for each revolution of the gear 55 (Fig. 1) associated with the unit M.

The unit M has only one of its pins 21 connected in the series circuit. Consequently, one rotation of the gear 55 associated with the unit M results in two interruptions of the series circuit. If desired, the pin 33 and its associated contact strips of the unit M may be associated with another totalizing circuit. Gearing may be employed to provide any desired number of revolutions of the armature disc for each circuit interruption by the associated contact device.

The successive operations of the pins 21 and 33 may be more clearly understood by reference to Figs. 5 to 8. Assuming that the parts are in positions shown in Fig. 5, the springs 41 and 49 maintain the levers 29 and 35 in the positions illustrated. As the gear 55 rotates in a counterclockwise direction for 90, the cam 53 moves the link 39 from the position illustrated in Fig. 5 to that illustrated in Fig. 6. Such movement of the ling 39 rotates the line of action of the spring 41 about the pin 291) until it crosses the shaft 3|. Thereupon, the spring rapidly urges the lever 29 in a clockwise direction from the position illustrated in Fig. 5 to that illustrated in Fig. 6. It will be observed that the rotation of gear 55 also moves the link 45 in a counterclockwise direction about the shaft 4|. However, in Fig. 6, the link 45 has not yet rotated the line of action of the spring 49 about the pin 35b sufficiently to cross the shaft 3|. For this reason, the position of the lever 35 remains unchanged.

As the gear continues to rotate through another angle of 90, the parts approach the positions illustrated in Fig. 7. It will be noted that the link 45 has rotated in a counterclockwise direction about the shaft 4| from the position illustrated in Fig. 6 sufficiently to carry the line of action of the spring 49 about the pin 35b until the line of action crosses the shaft 3|. In response to such movement of the line of action,

the lever 35 is urged rapidly by the spring 49 from the position it occupied in Fig. 6 to that illustrated in Fig. 7.

Rotation of the gear 55 for another 90 carries the parts from the positions illustrated in Fig. 7 to those illustrated in Fig. 8. The link 39 has moved in a counterclockwise direction sufliciently to rotate the line of action of the spring 41 about the pin 29b until it crosses the shaft 3|. This results in a rapid rotation of the lever 29 from the position illustrated in Fig. 7 to that illustrated in Fig. 8. It will be noted that the pin 21 has returned into engagement with the contact strip ll. However, during the movements outlined in Figs. 5 to 8 the contact pin 2'! has twice opened the circuit associated with the contact strips 1 and I! for brief intervals. A still further rotation of the gear 55 for 90 returns all parts to the positions illustrated in Fig. 5.

By inspection, it will be observed that when one of the links 39 occupies the positions illustrated in Figs. 6 and 8 substantially no load is applied to the gear 55 by the spring 41. Furthermore, when the lever 45 occupies the positions illustrated in Figs. 5 and 7, substantially no load is applied to the gear 55 by the spring 49. Because of the alternate application of load to the gear 55 by the springs 47 and 49, the resultant load on the gear 55 is maintained reasonably uniform. In this discussion, the small friction load has been neglected, but this load is itself substantially uniform.

Although the invention has been discussed with reference to certain specific embodiments thereof, numerous modifications are possible. Therefore, modifications embodying the invention are intended to be within the scope of the appended claims.

We claim as our invention:

In a device suitable for actuation by an electrical meter to generate electrical impulses having a rate of generation dependent on the rate of rotation of the meter armature, a first member, a second member, supporting means mounting said members for independent rotation between predetermined limits, a first element, a first spring extending between the first member and the first element, said spring engaging said first member at a first point displaced from the axis of rotation of the first member and biasing said point in a direction having a component urging the point towards said axis, a second element, a second spring extending between the second member and the second element, said second spring engaging the second member at a second point displaced from the axis of rotation of the second member and biasing said second point in a direction having a component urging the point towards the axis of rotation of the second member, means mounting the elements for independent movement in predetermined paths relative to the associated members for carryin the line of action of each spring across the axis of rotation of the associated one of said members in order to operate the members between said predetermined limits with snap actions, an operating unit, means mounting the operating unit for rotation relative to the supporting means, a separate cam mounted on said unit for cyclically actuating each of said elements through said predetermined paths, said cams being angularly disposed relative to the axis of rotation of the operating unit for successively operating said members with snap action at equally spaced intervals of each revolution of the operating unit, whereby the resultant load of said members on the operating unit is substantially uniformly distributed over a revolution of the operating unit.

PAUL G. ADAMS. MAX W. AXIVIAN.

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

UNITED STATES PATENTS Number Name Date 397,657 Meyer Feb. 12, 1889 1,490,704 Larsh Apr. 15, 1924 2,096,402 Molloy Oct. 19, 1937 2,204,949 Riche June 18, 1940 2,284,644 Dubilier June 2, 1942 2,424,626 Oberdick July 29, 1947 2,428,034 Nichols et al. Sept. 30, 1947 2,429,813 Hausler Oct. 28, 1947 2,439,747 Nelson Apr. 13, 1948 2,447,871 Riche Aug. 24, 1948

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