US3257536A

US3257536A - Short duration electrical switch

Info

Publication number: US3257536A
Application number: US305414A
Authority: US
Inventors: Eugene S Smith
Original assignee: W D METCALFE
Current assignee: W D METCALFE
Priority date: 1963-08-29
Filing date: 1963-08-29
Publication date: 1966-06-21
Anticipated expiration: 1983-06-21

Description

June 2li? T1966 E. s. SMITH 3,257,536

SHORT DURATION ELECTRICAL SWITCH Filed Aug. 29, 1963 5 Sheets-Sheet 1 rfv/32 QMS 52 L \32 24 I l l ,9 se f 24 l n, i \\O/ ,I9 6 A f /o/lg '9 El: CYL/'9 se f le(I 36- 56 54 A 58 se 44 46 Nm 4e 42 I9 --rs 6 x I4 i1 I D 4o l 52 INVENTOR. Fig 5 EUGENE s. SMITH ATTORNEY June 21, 1966 E. s. SMITH SHORT DURATION ELECTRICAL SWITCH 5 Sheets-Sheet 2 Filed Aug. 29,. 1963 INVENTOR.

EUGENE s. SMITH ATTORNEY June 21, 1966 E. s. sMlTH SHORT DURATION ELECTRICAL SWITCH 5 Sheets-Sheet 3 Filec'l` Aug. 29, 1963 muws mvENToR.

EUGENE s.smTH lav/@MMM ATTORNEY United States Patent O This invention relates to electrical switches of the type I in which the intended or desired duration of make or break is relatively short. In particular it has t -do with switches of a type which may be actuated, for the most part, by finger pressure, and since retrograde movement in such an operation involves a time lag due to inertia, and

motor responses in the body senses, it is an object of the invention to provide -a switch in which the release, after contact, is automatic, and therefore rapid, and not depend-ent upon reversal of the switch-actuating force, whether the latter is manually applied, or by mechanical means.

e More particularly, it is an object to provide an vautomatically openable switch comprising a spring-biased, reciprocating operating rod, with guide means for lateral displacement in a path of circuitous travel.

In still greater particular, it is an object to provide a switch having a reciprocating operating rod, normally spring-biased to idle position, a guide track for constraining part of said rod to a circuitous path including a switch contact in its m-otion of reciprocation, and opposed spring means acting laterally on said rod, at spaced points along its length and effective sequentially during reciprocation.

These and other objects, which will be apparent, are attained by the present invention, a preferred form of which 'is described in the following specification, as illustnated in the drawing, in which;

FIGURE 1 is an axi-al, sectional View through a switch unit, showing one of the separate halves of the casing in elevation,

FIGURES 2 and 3 are views similar to FIGURE 1, showing successive positionsof the push rod,

FIGURE 4.is a vertical section, axially of a portion of the push rod, taken on the plane of the line 4-4 of FIG- URE l, v

FIGURE 5 is -a view similar to FIGURE 4, taken on the plane of the line 5--5 of FIGURE 2,

FIGURES 6 and 7 :are transverse, sectional views, taken on the Vplanes of the lines 6-6 and 7--7, respectively, of FIGURE 1,

FIGURES -8, 9 and 10 are views similar to FIGURES 1, 2 and 3, showing a modified form of actuator,

FIGURES 11, 12, 13 and 14 are `sectional views, taken onthe planes of the respective lines 11.-11, 12.-12, 13-13, and 14-14, of FIGURE 8,

`FIGURES 15 and 16 `are'views siimlar to FIGURES 1, 2 Iand FIGURES 8, 9, and

` FIGURE 17 is an enlarged View of the area indicated by lthe dashed-line, rectangular loop 17, in FIGURE 16.

Referring to the drawings by characters of reference there is shown `a switch box 10, suitably secured, as by long screws 12, to the housing 14, containing an actuating unit for the switch. As seen in FIGURE 6, the housing 14 is composed of two

halves

16, 18, separated along a medial, longitudinal plane, and one being constructed in mirror image relation to` the other, and having bores 19 for connecting the parts with screws or bolts. As seenin FIGURE 56, the upper part of housing 14 is square in cross section, with a chamber 2t), circular in cross section, while the lower part is rectangularly oblong in cross section, being narrower than the upper part, and has an inner chamber 22, rectangular in section, .and geometrically similar to the outer cross section of the lower part.

Patented June 21, 1966 ICC Upper chamber 20 of the housing communicates with the exterior through an elongate, gener-ally elliptical slot 24, and communicates with the lower chamber 22, through a similar slot 216, formed in a septum 28, which separates the two chambers. A push rod or actuator 30, with push button head 32, extends from outside the housing through slot 24, chamber 20, and slot 26, into chamber 22, and has a middle, reduced portion 34, deiining a shoulder which serves as a stop for a washer 36. A compression coil spring 38, surrounding reduced section 34 of the push rod, acts between septum, or bridge, 28, and washer 36, urging the latter normally against the top wall of the housing, containing slot 24, which represents the uppermost, or idle position of the push rod.

As the push rod is urged downward, its bottom end, which moves wholly within the lower chamber 22, is constrained to lateral components of motion, and consequent movement in a closed loop, by cam track and follower means, the former provided by grooves inthe chamber, and the latter by lateral protuberances on the push rod. Thus, opposite walls of chamber 22 are each provided with a grooved channel, of larcuate cross section, and g-enerally triangular in overall form, comprising la first section 40 defining a first path, which accommodates the push rod end on its downward stroke, a short, horizontal section 42 defining a second path, 4at the bottom of the stroke, and a generally vertical section 44 defining la third path, which guides the return stroke upwards, and which merges at the .top of the stroke with the initial passage 40, where the push rod is positioned for the next cycle of operation. The grooves just described leave, in each wall, a central island, or'boss, 46. Preferably this boss will be cut away along a line 4S (FIGURES 1 andI 2) to provide a flared, lower end, or mouth, for `the return groove 44, to ensure entry of the follower into the return groove.

The follower means on the push rod are constituted by a pair of oppositely disposed, laterally Iextending pins S0, near the lower end of lower portion 52 of the push rod, with hemispherical outer ends yadapted to substantially mate with, and nest in, the cam grooves, for sliding movement therealong. In the cam and follower action, the lower end of the push rod is urged laterally, by spring action into groove 40 on the first part of the cycle, and in the opposite direction by another spring means, -along bottom groove 42, for entry into return groove 44, at the bottom of the initial stroke. Thus, a double-headedl pin 54, slidable in a lateralopening in a boss 56 on the housing, has la compression spring 58 in surrounding relation to its shank, which urges it into contact with lower portion 52 of the push r-od on a line passing through the upper junction of the two vertical grooves, so that the push rod will always be urged into groove 40 upon initial down- 50 are engaged in groove 40, this bias becomes unnecessary, .and the push rod moves away from pin 54 which remains at the innermost position of its sliding motion, with its outer flange 60, abutting the housing.

The lower end S2 of the push rod carries a metallic, hemispherical head 62, as an insert, which isintended to make simultaneous, circuit-closing-contact with the terminal prongs 64, of leads 66, secured within switch box 10 by bolts 68, serving as binding posts for the circuit leads. As seen in FIGURES 2 and 5, -this circuit-closing contact by the push-rod head is accomplished when the followers 5t) a-re near the bottom of the stroke, and positioned for entry into the short, lower, transverse grooves 42. At this stage the lower end of the push rod` is subject to a spring bias engendered by its contact with and depression of a d-ouble-headed pin 70, slidable in suitable openings in housing 14 and switch box 10, and having an inner, domed head 72, under the constant bias of a surrounding 3 compression spring 74, which maintains the head 72 normally in the path of travel of the push rod end 52 along Ithe path of grooves 40. For guaranteed operation, the conducting head 62 should make bridging contact of the prongs 64 just prior to' arrival of the follower pins to a position permitting entrance into the bottom groove 42, with the prongs yielding in aV slight degree of bend to permit' completion of the downward stroke for such entry. This interval of pre-contact may, -of course, be extremely b-rief, and upon arrival of the followers at the entry position, the spring 74 is immediately effective to move the followers across lower grooves 42, thus opening the circuit, in spite of the fact that finger pressure on the push rod is still effective. Thereafter, the push rod is dev barred by spring 74 from either closing the circuit, or reentering groove 40, and after cessation of the depressing force on lthe push rod head, spring 38 returns the push rod upwardly, with grooves 44 guiding it to the starting position of the switching cycle, and energizing spring 58 in the process. In this upward movement, the guidance of the followers into the return grooves 44 is aided by the ared configuration of the lower ends of these grooves.

The modification illustrated in FIGURES 8 through 14 is generally similar to that just described in respect to the push rod and closed-loop cam grooves, but in lieu of a bridging of leads by the push rod, the l-atter serves to actuate a conventional `push -p-in 84, which is normal component of a commercially available switch, such as a micro-switch. Thus, the housing 76 is generally similar to housing 14, and carries a spring-urged push rod 78, with a lower, spherical head 80, adapted to ride cyclically ina triangular configuration of cam grooves similar to those in FIGUREl 1.

The switch box 82 has the protruding, push pin 84, controlling a circuit represented by

terminals

86, 88, and this push pin in actuated on acontact byra leaf spring 90, secured to an inner wall of the lower compartment of housing 76, by rivets 92, and extending across the grooves representing the path of downward movement of the push rod head 80. For certainty and lrapidity of action, the leaf spring 90 may have the assistance of a push pin 94 slidably mounted -in a tube 96 in switch box 82, and extending into housing v76 through an opening therein, and backed by a compression spring 98, whichV urges theA leaf spring 90 to its normal position, athwart the cam grooves.

It will be seen that, as in the case of the other modification, pressure on the push rod 78 will result in movement of round head 80 downward along the right hand pair of grooves, in which movement the leaf spring 90 is swept aside, against the spring pressure on pin 94, with switch action being effected by pin 84, after contact by leaf 90, and immediately prior to ar-rival of head 80 a-t the position shown in FIGURE 9, where it is ready for entrance into the bottom groove. At this position, shown upon FIGURE 9, both the leaf spring 90 and the springpressed pin 94 urge the head 80 along the bottom groove, and in this movement the pin 84 is released. As in the case of the other modication, duration of the switch action is momentary only. Also similarly to the other modification, the head 80 returns up the left hand grooves, to sta-rting position, after release of pressure from the head of push rod 78. FIGURE shows the positions of the parts after head 80 has been moved to its extreme leftward position as viewed upon FIGURES 8, 9 and 10, and is about to be elevated to the starting position of FIGURE 8 and 11 by the urge of the coil spring surrounding rod 78.

The modification shown in FIGURES through 17, which represents a preferred embodiment of the invention, differs from the first two described modifications in providing an improved application of force vectors, in the wiping action on the laterally applied, spring-biasing means, and in providing a yieldable reciprocating member in the switch-closing mechanism, whereby adjustment of the switch gap lis permissible. Yet another difference resides in the integral construction of the push rod housing and the switch box, whereby all the mechanism may be laid in one half of the shell, and the other half then laid on, and secured by bolts or screws.

Thus, the push rod housing of FIGURES 15 through 17 is integral with the switch box 102, in each of two shell halves, secured together by five screws or bolts through bores 104. Push rod 106 is substantially the same in structure, location and function as rod 30 of FIGURE l, and the cam grooves in which it is guided are the same as the grooves 40 through 44 of FIGURE 1. The elements `differing from what is shown in FIGURE 1 will be best understood with reference to enlarged view FIGURE 17. Therein it will be seen that the lower, lateral, b-iasing means 10S7 is not contacted directly by the head integrally fixed with the lower end of rod 106 but, to the contrary, by a swingable leaf or slab 112, pivoted at the medial partition 114, and extending downward to a position where its lower end portion is in covering relation to the outer end of the reciprocator 108, which latter will presently be described. For pivotal mounting, the leaf 112 has an integral, cylindrical, upper head 116, with axis transversely disposed, which constitutes a set of trunnions, the ends of the head being journalled in suitable bores in the meetingrhalves of partition 114. A cylindrical segment 118, integral with and depending from the lower surface of the partition, serves the dual function of holding the head against downward removal from its trunnion mounting, and of providing a stop, limiting clockwise movement of the leaf. By this arrangement, it will be seen that contact of the push rod with the reciprocator 108 in a manner to provide unfavorable angles of the applied force vector with respect to the axis of the reciprocator, is avoided, and the relatively long, effective radius of leaf 112 gives a force direction which is substantially axial as to the reciprocator 108, and substantially transverse to the cam groove, for equally favorable contact with the push rod. Although the upper biasing means has been shown as structurally similar to that of FIGURE 1, it will be understood that here, also, the intervening, swinging member may be employed to advantage.V

The switch mechanism in the box 102 may be completely assembled, apart from the switch housing, and then deposited, as a unit, in the appropriate niches in one of the housing halves. This mechanism comprises a fixed, but adjustable contact portion 122, and a movable contact portion 124. The fixed portion is based on a metallic bushing, or nipple, 126, axially threaded at its inner end to receive a threaded shank 128, extending within the chamber of box 102, and carrying at its inner end therein, a disc-form head 130, constituting one of the circuit-closing, electrical contacts. The position of head is `adjustable by turning of threaded shank128, for which purpose the outer end of the shank hasa slot 132 to accommodate a screw driver. The shank 128 is locked in adjusted position by means of a screw 134, in a threaded counterbore in nipple 126, and a lead terminal 136 is held in contact with the nipple by means of a nut 138 on screw 134.

The movable portion of the switch contact mechanism comprises a contact disc 140, similar to disc 130, screwconnected to a strip 142 of flexible, conducting material such as braided cable, or fiat leaf, and the flexible strip is in turn screw-connected to a conductor bar 144, embedded in a notch in the box wall, and having a transversely bent, outer end 146, bored to receive a securing screw 148, to which is secured the other terminal, 150, of the circuit leads.

Inner contact disc 140 is part of a reciprocating system,l

tition wall 154 of the housing, and disc 140 has an integral shank 155, slidably mounted in the tube 152, the sliding movement of the sha-nk being limited by a laterally disposedpin 158, carried by the shank, the ends of which extend through oppositely disposed, longitudinal slots 160, in the tube 152.

Wall 154 has a counterbore 162 accommodating a collar 164 on tube 1.52, which is engaged by a compression coil spring 166, surrounding the tube and constantly biasing the tube in a direction inwardly of the housing, that is, away from the position of switch contact. This inward movement is limited by the pin 158, engaging against a boss 168 on wall 154, `which stops the domed, inner end of the tube, and the leaf 112 which it pushes, at a position in the path of push rod 166. (See FIGURE 15.) In this position the switch points, or discs, are open, and the telescoping parts of the plunger 108 a-re extended to their fullest through action of a compression spring 170, carried in the blind passage of tube 152, and acting against shank 156. This expanding movement of adjustment is limited by contact of pin 158 with the outer ends of slots 160. It will be seen that in the case where the adjustment of contact disc 130 would not permit full movement of the rrider, sufficient to clear the cam groove, the inner spring 170 will yield, permiting telescopic collapse of the parts to the extent necessary for such clearance.

While certain embodiments have been shown and described, Ivarious modifications will be apparent, in the light of this disclosure, and the invention should not, therefore, be deemed as limited, except insofar as shall appear from the spirit and scope of the appended claims.

I claim:

1. In a device for momentarily closing an electric circuit, a circuit closer, an actuator having a longitudinal axis, means mounting said actuator for movement along said axis and for pivoting in a plane containing said axis, means engaging and positively guiding one end of said actuator, in succession, from a point of beginning in a rst path along said axis, a second path transversely of said axis, and a third and return path along said axis to said point of beginning, and means operated by and in response to movement of said end of said actuator substantially into the intersection of said rst and second paths to actuate said circuit closer.

2. The device of claim 1, and means urging said actuator along said axis away from said second path to position said one end thereof at said point.

3. The device of claim 2, and means engaging said actuator at said point and urging said one end thereof into said first path.

4. The device of claim 2, and means engaging said actuator at said intersection of said rst and second paths and urging said one end thereof into and along said second path.

5. In a device for momentarily actuating a circuit closer, a casing having spaced side walls, an actuator having a longitudinal axis and extending through an opening in said casing, first means fixed with at least one said side wall and engaging and positively guiding the end of said actuator Within said casing, in succession from a point of beginning, along a first path along said axis, a second path transversely of said axis, and a third and return path along said axis to said point of beginning, second means yieldingly urging said actuator along said axis to position said end thereof at said point, and means operable to actuate a circuit closer by and in response to movement of said one end of said actuator into the intersection of said first and second paths, against the urge of said second means.

6. The device of claim 5, meansengaging said actuator at said point of beginning and urging said end thereof into said first path, and means engaging said actuator at said intersection of said first and second paths and urging said end thereof into and along said second path and into said third and return path.

7. The device of claim 5, said first means comprising first and second closed channels each in a respective one of said side Walls and each having a section defining respective ones of said paths, and means carried by said rod adjacent said one end thereof for guided movement in and along said channels.

8. A device for momentarily actuating a circuit closer, comprising a casing having spaced side walls, a rod having a longitudinal axis and extending into said casing between said walls, means mounting said rod for pivoting in a plane between said walls and containing said axis and for movement relatively to said casing along said axis, there being first and second closed channels each in a respective one of said walls and each defining a first path extending from a point of beginning, along said axis, a second path transversely of said axis in said plane, and a third-path returning to said point, follower means carried by said rod adjacent the end thereof within said casing and slidably fitting said channels for guided movement thereby, spring means yieldingly urging said rod into position locating said follower means at said point of beginning, spring means engaging said rod and urging said follower means when at said point, into said first path, spring means engaging said rod and urging said follower means when at the intersection of said lirst and second paths, into and along said second path and into said third path, a circuit clgser xed with said casing and including a part projecting into said casing, said part being momentarily engaged to close and open a circuit by and in response to movement of said follower means substantially into the intersection of said first and second paths.

References Cited by the Examiner UNITED STATES PATENTS 1,732,577 10/1929 Durdin 20o-s4 2,083,118 6/ 1937 Goldstone. 2,151,858 3/1939 Maysip et al. 74-151 3,142,743 7/1964 Borges 200--160 3,144,537 8/1964 Kiwi. v

ROBERT K. SCHAEFER, Primary Examiner'.

KATHLEEN H. CLAFFY, Examiner.

D. SMITH, I R., Assistant Examiner.

Claims

1. IN A DEVICE FOR MOMENTARILY CLOSING AN ELECTRIC CIRCUIT, A CIRCUIT CLOSER, AN ACTUATOR HAVING A LONGITUDINAL AXIS, MEANS MOUNTING SAID ACTUATOR FOR MOVEMENT ALONG SAID AXIS AND FOR PIVOTING IN A PLANE CONTAINING SAID AXIS, MEANS ENGAGING SAID POSITIVELY GUIDING ONE END OF SAID ACTUATOR, IN SUCCESSION, FROM A POINT OF BEGINNING IN A FIRST PATH ALONG SAID AXIS, A SECOND PATH TRANSVERSELY OF SAID AXIS, AND A THIRD AND RETURN PATH ALONG SAID AXIS TO SAID POINT OF BEGINNING, AND MEANS OPERATED BY AND IN RESPONSE TO MOVEMENT OF SAID END OF SAID ACTUATOR SUBSTANTIALLY INTO THE INTERSECTION OF SAID FIRST AND SECOND PATHS TO ACTUATE SAID CIRCUIT CLOSER.