US2019862A - Switch box - Google Patents

Description

Nov. 5, 1935. E. G. JOHANSSON SWITCH BOX Original Filed Aug. 19, 1931 fez/6% fir Patented Nov. 5, 1935 SWITCH BOX Ernest G.'Johansson, Watertown, Mass., assignor to The Palmer Electric & Manufacturing 00., Waltham, Mass., a corporation of Massachusetts v Original application August 19, 1931, Serial No.

Divided and this application January 4, 1933, Serial No. 650,115

8 Claims. (01. 200-77) This application is divided from my copending application Serial No. 558,038, filed August 19, 19.31. The invention relates to improvements in boxed electrical switches. When current-carrying circuits are made or broken bythe throwing of .a .switch, it is desirable that the closing or opening movement of the make -and-break memher be rapid, especially on the break, so as to minimize sparking at the terminals with resultant injury thereto. To this end a snap-action mechanism is provided .by which movement of the make-and-break member-of theswitch is made against a resilient force up to a certain point, after which this force assists the movement. of the member to, the-end of its stroke andcauses rapid motion thereof. According to the invention the switchis housed in a box a portion of .which is stifily resilient and is employed in producing the snap-action. In the embodiment of theinvention illustrated on thedrawing and. hereinafter described, a box having a bottom wall of sheet metal or other stifily resilient ,material is employed. The operatingmechanism forv the makeand-break member of the switch is so arranged as to distort the bottom of the box. during the early part of its stroke in either direction, the resilient force of the distorted box bottom acting to move the member through the remainder of its stroke. As the bottom of thebox is stiff, the restoring force is considerable so ,that the remainder-of the stroke of the make-and-break member is very rapid. The contact element on the make-and-break member is arranged with reference to the fixed contact or contacts which it engages so that the actual separation of the engaging contacts occurs during the rapid portion of the stroke of the make-,and-break member. I r

The operating means for the make-and-break member may include a rock-shaft. In the embodiment .of the invention hereinafter described, a rock-shaft is mounted parallel to the bottom of the. box and is supplied witha cam member shaped to spring a portion of the shaft and a portion of the box bottom away from each other. In order to obtain a restoring force for the opera-'- tion of themake-and-break membergthe box bottom may be resilient, as hereinbefore set forth, orthe rock-shaft may be resiliently yielding, or

, both the shaft and box bottom may yield.

For a more complete"understanding of the invention, reference may be had to the description thereof which follows, and to the drawing, of which, I V

Figure'l is an elevation, partly broken away to show in section, of a switch box and switch embodying the invention.

Figures 2 and 3 are partial views of the same,

showing the parts in different positions of operation.

Figure 4 isa perspective view of the snap-action the apparatus illustrated, the box will be considered as lying with its back on a horizontal surface, the hinged cover thus forming the top of the box. It is understood, however, that the box in actual use may be mounted in any desired position and is ordinarily fixed to a vertical wall. The bottom of the box is suitably pierced to receive screws l4 by which the box may be secured to a supporting wall l5, and is preferably offset from the supporting wall I5 by small bulges projecting outwardly as at I! from the bottom of the box, preferably around the holes for the screws I4.

The fixed current-carrying elements within the box are all mounted on a suitable unit block 25 which is preferably of molded porcelain or other suitable insulatingmaterial. The block is pierced vertically by a pair of holes 39 into which project portions of the switch elements, these holes The box and cover may bemade 10 serving as cavities or pockets in which the cur-' rent-rupturing separation of switch elements takes place so that the arcs are partially enclosed by the adjacent portions of the block 25. The holes 30 each include a pair of vertical grooves 3| which guide a sliding barrier 33 carrying a makeand-break or movable switch element 40 thereon.

The make-and-break member 49 is arranged to make contact with fixed terminal members 4| and 42 to close the switch when the barrier 33 is moved upward. Suitable means for moving the barrier members 33 up and down are provided. As shown on the drawing, each barrier member is pierced near its lower end as at 34 to receive the reduced end of an arm 35. These arms are preferably made of insulating material such as vulcanized fiber and are mounted on a rock shaft 60 The rock shaft 66 as shown on the drawing is preferably made of fiat bar stock of steel or other suitable material, and preferably has: a bent portionii! at one end acting as a crank arm with handle element 62. The arms 35 which operate the barrier members 33, are preferably slotted so as to fit loosely on the rock shaft. Since this slot in non circular, the arms 35 rock with the shaft 60. The shaft 60 may have a reduced portion 88 to bear in an aperture in a side wall of the box. As shown, an ear 65 is provided as a bearing for the end of the shaft remote from the handle, the ear 65 being secured to the bottom of the box. 1

For the more effective quenching of arcs between the bridging conductors 40 and the con tact members 4| and 42, it is desirable that the slides 33 be snapped or jerked downwardly when the conductors 40 are about to leave contact with the contact members in their circuit-breaking movement. A snap action device may be provided to produce automatically a short, quick downward jerk on the plates 33 at the proper moment when the switch handle is swung to break the circuit. The snap action'device illustrated on the drawing comprises a heart-shaped arm 10 of refractory material, thisarm having a downwardly tapering portion below the shaft 60 terminating in a rounded lower end I3. The arm 10 is of such .a length that in the lower portion of its swing with the rocking of the shaft 60 it engages the bottom of the box or an abutment element thereon. If that portion of the bottom of the box is spaced from the supporting wall l5,.it is free to give slightly. The shaft 60 'may also be slightly resilient. As the end portion 13 of the arm 10 reaches the bottom of its swing, the shaft 60 and a portion of the bottom of the box are sprung away from each other by engagement of the arm 10 with the bottom of the box or an abutment thereon. As the end portion 13 passes the lowermost point of its swing, the powerful restoring force arising from the stiffness of the shaft 60 and the bottom of the box presses strongly against one side edge or the other of the arm 10 and causes an exceedingly quick rotational movement of the shaft through .a small angle. This jerks the plates 33 up or down as the case may be. In the circuit breaking movement, the parts are so arranged that the jerk on the plates 33 comes just as the conductors 40 are leaving contact with the members 4| and 42.

The snap action may be produced by causing the end portion 13 of the arm 10 to engage di-' rectly against the inner face of the bottom of the box. As shown, however, an abutment member is mounted on the bottom of the box in the path of the end portion 13. The abutment member is preferably made of wear resisting material such as hardened steel. While the abutment member may be made in various forms, it is shown on the drawing in the form of a hardened steel pin 14 which may be held loosely against'the bottom of the box by a pair of loops l5 struck up from the bottom. This structure promotes a quick jerk which can be closely timed to occur at any desired point of the stroke of the operating handle. The loose mounting of the pin 14 permits the pin to turn on its axis to present different portions of its periphery for engagement with the arm 10. This greatly prolongs the life of the abutment member.

It is evident that various modifications and changes may be made in the structure herein described and shown, without departing from the spirit or scope of the invention as defined in the following claims.

I claim:

1. Apparatus of the class described, comprising a box having a stiiiiy resilient wall portion, an electrical switch inside said box, means movable back and forth through a definite s roke for 0D- from the surface of the wall on which it is mountportion of its stroke.

2. Apparatus of the class described, comprising a box, an electric switch mounted therein, and 10 means for operating said switch, said means including a make-and-break element, a stifily resilient shaft mounted .in parallel spaced relationship to the bottom of the box and rockable to move said make-and-break element, and a snap action device having an abutment member off the bottom wall of said box and a rigid arm mounted to rock with said shaft and to engage said abutment member.

3. Apparatus of the class described, comprising a box having a bottom, an electric switch mounted within the box and having a make-and-break element, and means for operatingsaid switch, said means including a shaft parallel to said bottom and rockable to move said make-and-break element, and a spring snap action device includ ing means for springing portions of said shaft and adjacent box bottom away from each other when the shaft is in a predetermined phase of its 30 rocking motion.

4. Apparatus of the class described comprising a box, an electric switch mounted within the box and having a make-and-break element, and means for operating said switch, said means including a stiffly resilient shaft rockably mounted 3 in parallel spaced relation to a wall of the box and operably connected with said make-andbreak element, and a spring snap action device having an arm mounted on said shaft to rock therewith and an abutment member mounted in the path of a portion of said arm.

5. Apparatus of the class described comprising a box having a stifily resilient wall, an electric switch mounted therein, and means for operating said switch, said means having a spring snap 45 action device which includes said resilient wall of the box as an active element. 6. Apparatus of theclass described, comprising an electricrswitch, a box containing said switch, said box having cooperating members consisting of the bottom wall thereof and a rockable shaft, one of said members being yieldable, means including said shaft actuable to open and close said switch, and a snap-action device comprising a rigid arm on said shaft and rockable therewith and a wear-piecemounted in the box adjacent to said bottom wall and engageable by a portion of said arm in its rocking motion to spring said arm and. box bottom away from each other.

7. Apparatus of the class described comprising a box adapted to be mounted on a wall, an electric switch mounted in said box, means projecting outwardly from the bottom of the box whereby a substantial portion of said bottom is'spaced ed, switch-operating. means including a shaft rockable to open and 'close the switch, and a snap action device comprising an arm mounted on said shaft to rock therewith and an element projecting inwardly from the bottom of the box into the path of a portion of said arm.

8. Apparatus of the class described, comprising an electric switch, a box containing said switch,

said box having cooperating members consisting 75 of the bottom wall thereof and a rockable shaft, one of said members being yieldable, means including said shaft actuable to open and close said switch, an arm mounted on said shaft and extending toward said wall, the end portion of said arm having converging cam edges, and a cylindrical wear-piece rotatably mounted on said wall in the path of the end portion of said cam for yieldably moving said wall and shaft relative to each other.

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