US2523125A - Switch - Google Patents

Description

Patented Sept. 19, 1950 SWITCH Gordon S. Loy, Belmont, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 30, 1946, Serial No. 706,737

6 Claims.

This invention relates generally to electric control switches, and more specifically to such switches adapted to be operated by housing doors.

Where electrical apparatus is mounted in an enclosure it is generally desirable to provide a control switch for the apparatus to be operated by the door for the enclosure so that the switch will be closed to energize the apparatus when the door is closed, and will open to de-energize the apparatus when the door is opened. While such an arrangement is satisfactory from a safety standpoint, there are occasions when it is necessary to have the apparatus energized when the door for the enclosure is not closed, as during certain repair and test operations, or for emergency operation in cases where the door may be damaged or destroyed entirely.

Accordingly, one object of this invention is to provide in a door-operated type of electric switch adapted to be closed when the door is closed and open when the door is open, novel means for selectively closing the switch when the door is open.

Another object of this invention is to provide in a door-operated type of electric switch adapted to be closed when the door is closed and open when the door is open, novel means for manually closing the switch when the door is open, and for automatically resetting the switch for operation by the door in response to closing of the door.

A more general object of this invention is to provide in a switch which is biased to one operative position and is provided with a reciprocable operating member, novel means for selectively retaining the operating member at its position corresponding to the other operative position of the switch.

Another object of this invention is to provide in a switch which is biased to one operative position and is provided with a reciprocable operating member, novel means for selectively retaining the operating member at its position corresponding to the other operative position of the switch, and operative automatically in response to operatin movement of said member to release the retaining means.

Another object of this invention is to provide in connection with electrical apparatus mounted in a housing, a novel control switch for the apparatus adapted to be closed by closing of the housing door and opened when the door is opened, and yet being capable of manual adjustment to be retained at closed position when the door is open and to be automatically released on a subsequent closing of the door,

Still another object of this invention is to provide a novel attachment for a standard type of switch, whichattachment includes operating and latch means for the switch.

These and other objects of this invention will become more apparent upon consideration of the following description of a preferred embodiment thereof, when taken in connection with the attached drawing, in which:

Figure 1 is a front view of a housing for elec-. trical apparatus embodying a control switch constructed in accordance with this invention;

Fig. 2 is a partial sectional view of the housing shown in Fig.1, with the housin door shown in dot-dash lines at a partially open position;

Fig. 3 is a side view of the switch structure employed with the housing of Figs. 1 and 2; and

Fig. 4 is a longitudinal section view of the switch shown in Fig. 3.

The housing 2 shown in Figs. 1 and 2 may comprise side walls 4, a top wall 6, and a front wall 8 defining an opening for a door Ill. The housing may also include a rear wall (not shown) The door II] is preferably hinged on one side as by hinges i4, and has an operating knob l2 or the like at the opposite side thereof, to facilitate openin and closing of the door.

Any desired electrical apparatus [6 may be mounted within housing 2, and in order to supply electrical energy to such apparatus, supply conductors I8 and 29 are provided with the former being directly connected with apparatus l6, and the latter being connected with apparatus l6 through a control switch 22. The control switch 22 is illustrated as being secured to the inner side at the top of front wall 8 of the housing, as by bolts or rivets 24, in a position such that the operating member of the switch is adapted to be engaged by door In adjacent to the closed position of the door so as to be opened and closed by the door.

Control switch 22 preferably employs a standard design of switch unit 26 of the type having separable contacts, one of which is spring biased out of engagement with the other, and having an actuating plunger which may be depressed to close the contacts, and having some overtravel in the circuit closing direction. Such a switch is illustrated in Figs. 3 and 4 as comprising a generally tubular base 28 of insulating material preferably a molded insulating material, having contact strips 30 inserted in one end of base 28 in opposed relation, with each strip having a laterally extending contact portion 32 adapted to extend towards each other, and to engage an internal shoulder 34 formed integrally with base 28. The contact strips are held in base 28 by a substantially cup-shaped plug 36 which is inserted in the base between the contact strips and is secured therein together with the contact strips 30, by opposed screws 38 extending through apertures in the opposite sides of base 28 and through contact strips 36 to be threadedly engaged in opposite sides of plug 36.

The opposite end 40 of base 28 is interiorly threaded for threadedly receiving one end of a guide tube 42. An operating plunger 44 is provided with an enlarged base portion 46 adapted to relatively closely slidably fit within guide tube 42 and to be normally held in engagement with a shoulder 48 provided at the outer end of guide tube 42, by a coil compression spring 50 reacting between plunger base 46 and shoulder 34 in base 28. Within guide tube 42, plunger 44 is provided with a contact carrying rod 52, preferably threaded into base 46 of the plunger, and provided with a head 54 at its inner end, on which a bridging contact disk 56 is adapted to be held by a coil compression spring'58 reacting between contact disk 56 and plunger base 46.

It is apparent from the foregoing that the switch unit 26 will operate substantially in the manner previously described, that is, the circuit through the switch is normally held open by compression spring 50, which also serves to maintain plunger 44 at an outer position. When it is desired to close the circuit through the switch, plunger 44 is moved inwardly relative to the switch and the, circuit is closed when bridging contact disk 56 engages contact parts 32 of the conducting strips 30. It will be noted that plunger 44 may be moved beyond the point where bridging contact disk 56 engages contact parts 32 because contact disk 56 is slidable on rod 52, and the disk will be held in engagement with contact parts 32 by compression spring 58, and the plunger may have, therefore, over-travel relative to bridging contact disk 56 until the head 54 thereof engages the outer end or plug 36. Obviously, as soon as plunger 44 is released, compression spring 50 Will operate'to restore the plunger to its extended position shown in the drawing.

In accordance ard type switch as the switch unit 26 is adapted to be provided with an operating and control unit which is operable toretain the switch actuating plunger at a closed circuit position, and is adaptedto be automatically released from such a powith this invention, such a standsition-during over-travel of the operating plunger relative to the'bridging contact. For this purpose, a guide tube 60 is internally threaded at one end, so as to be threaded onto the outer end of guide tube 42 and be secured in adjusted position thereon by a lock nut 62. 'A plunger 64 is adapted to be slidably mounted in the outer end of guide tube 60 and hasa reduced outer end portion366', adapted to be actuated by a door, such as the door 10 of housing 2, or the like. The outerend 66 of the plunger may be provided with a transversely extending slot 68, for a purpose to be described. Plunger 64 is provided adjacent its inner end with a transverse pin 10 secured therein and adapted to project therefrom into an elongated slot 12 provided in guide tube 60. Slot [2 extends longitudinally in the direction of sliding movement of the operating plunger, and opens at one side intoa locking recess 14 which extends at an inclination relative to the extent of slot 12; Inorder to mount the switch device illustrated'in the drawing, a mounting bracket 16 is provided with a relatively large threaded opening adapted to be threaded on the outer end of guide tube 68, and to be secured in adjusted position thereon by a lock nut 80. Mounting bracket 16 is also provided with mounting apertures 18 for receiving the mounting bolts 24.

It will now be apparent that with the switch structure in its normal open circuit position illustrated in Fig. 4, the circuit may be closed by pushing plunger 64 to the right to thereby push plunger 44 to the right and close the circuit through the switch unit in the manner described above. Similarly, when the motive force is removed from plunger 64, the switch will automatically be opened by compression spring 50 and the parts restored to the positions illustrated. However, if it is desired to maintain the switch closed without the necessity of continuously exerting a force on plunger 64, the plunger may be pushed to the right until the closed circuit position is reached, whereupon pin 18 on plunger 64 will be opposite locking recess 14 in guide tube 60, so that by rotating plunger 64 in a clockwise direction pin 10 will be moved into locking recess 14 to prevent outward movement of the plunger and bridging contact 56 of the switch, and thereby maintain the switch at a closed circuit position. The transverse slot 68 in the outer end of plunger 64 permits the use of a screw driver, or the like, for rotating the plunger in the manner described above. or course, when it is desired to open the switch after it has been locked closed in the manner described above, plunger 64 may be manually rotated counterclockwise, but this is not necessary in view of the inclined relation of locking recess 14 with respect to slot 12, because it is apparent that if a force is exerted on plunger 64 tending to move it further inwardly so that it will over-travel with respect to bridging contact disk 56, pin 18 will be cammed out of locking recess 14 back into slot 12, so that when such force on the plunger is released, compression spring 50 will be free to move the plunger and bridging contact of the switch to the open circuit position illustrated.

The special utility of the switch structure described above, rendering its special adaption for operation by a housing door will now be apparent, because when such a switch assembly is mounted as shown in Figs. 1 and 2 so that the outer end 66 of plunger 64 is positioned to be engaged by the housing door just prior to complete closing of the door (Fig. 2), so that the plunger will be moved inwardly upon final closing movement of the door, the switch will be closed by the door when the latter is fully closed, and opened only when the door is opened. In case electrical apparatus I6 mounted within the housing is supplied with high voltage, this switch arrangement provides that the apparatus is energized only when the door is closed, so that it is impossible for anyone to open the door and accidentally come into contact with any parts within the 16 with the housing door open has passed, it is necessary that the switch be restored to its normal operation, that is, to be opened and closed by opening and closing of the door. It will be apparent that with the particular arrangement described above it will be impossible for an operator to neglect this feature as might be possible in the case of a switch latch requiring a separate manual operation to release it, because upon a subsequent closing of the door, plunger 64 is automatically released by movement of pin out of locking recess H and is thus automatically moved to its normal position where it will open upon a later opening of the door and will be closed when the door is closed.

From the foregoing, it is apparent that the structure disclosed herein provides a novel switch arrangement employing a switch having contacts and an operating member normally biased to one position, and adapted to be operated against the bias to its other position, together with means selectively operable to hold the switch at such other position against its bias, and means for automatically releasing the switch from such holding means upon predetermined normal operation of the switch. Furthermore, it will be apparent that the switch structure described is especially adapted for operation by a housing door, or the like, especially where the switch acts to control the supply of electrical energy to apparatus mounted within the casing, where it may be desirable to have the switch held at its position corresponding to that occupied when the housing door is closed, even when the door is open. Moreover, the switch structure described is adapted for use with a standard type of switch unit of the general type described.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is desired that this invention be not limited to this particular embodiment inasmuch as it will be apparent, especially to those skilled in the art, that many changes and modifications may be made in this particular structure without departing from the broad spirit and scope of the invention. Accordingly, it is desired that this invention be interpreted as broadly as possible, and that it be limited only as required by the prior art.

I claim as my invention:

1. In a switch, separable contact means, a reciprocable operating member for actuating one of said contact means to open and closed circuit positions, said one contact means and operating member being biased for movement in one direction to one position of said separable contact means, said operating member and movable contact means being normally free to move to said other position upon application of operating force to said operating member sufficient to overcome said bias and being free to return to said one position under the influence of said bias upon removal of said operating force, means providing for over-travel of said operating member with respect to said contact means in the opposite direction beyond the other operative position of said separable contact means, means responsive to movement of said member in another direction when at a position corresponding to said other contact position for holding said member at said position against movement by said bias, and cam means cooperating with a part of said member during over-travel thereof for releasing said holding means by moving said operating member in a direction opposite said other direction to restore said member for reciprocal movement.

2. In a switch, separable contact means, a reciprocable operating member for actuating one of said contact means to open and closed circuit positions, said one contact means and operating member being biased for movement in one direction to one position of said separable contact means, means providing for over-travel of said operating member with respect to said contact means in the opposite direction beyond the other operative position of said separable contact means, locking projection and recess means one of which is movable with said member and the other of which is fixedly mounted, said projection and recess means being normally out of engagement during reciprocation of said member but arranged so that said projection means will engage one side of said recess means when said member is rotated in one direction at a position thereof corresponding to said other contact position for holding said member at said position against said bias, and the other side of said recess means being inclined with respect to the direction of reciprocal movement to positively rotate said member back to normal position in response to over-travel of said member.

3. In a switch, separable contact means, a reciprocable operating member for actuating one of said contact means to open and closed circuit positions, said one contact means and operating member being biased for movement in one direction to one position of said separable contact means, means providing for over-travel of said operating member with respect to said contact means in the opposite direction beyond the other operative position of said separable contact means, a tubular guide for said member, a projection on said member normally received in an elongated opening in said guide during reciprocable movement of said member, said opening having side edges substantially parallel with the direction of movement of said operating member and movable contact means, and one side edge of said opening having an angularly extending recess therein positioned to receive said projection upon rotation of said member when at a position thereof corresponding to said other contact position for holding said member at said position against said bias, and the side of said recess means engaging said projection during over-travel of said member being cam-shaped to cause rotation of said member back to normal position.

4. In switching apparatus having a switch of the type comprising separable contacts biased apart and a contact operating plunger slidable in a guide tube, the combination of a separate operating unit having a second operating plunger slidably mounted in a second guide tube, means securing said tubes together in axially aligned relation to secure said unit in operative relation to said switch, and said second tube and operating plunger having interfitting recess and projection means arranged to retain said second plunger at one position against said bias in response to rotation thereof and to release said second plunger in response to predetermined sliding movement thereof.

5. In switching apparatus having a switch of the type comprising separable contacts biased apart and a contact operating plunger slidable in a guide tube, the combination of a separate operating unit having a second operating plunger slidably mounted in a second guide tube, means securing said tubes together in axially aligned relation to secure said unit in operative relation to said switch, a longitudinally extending slot in said second tube receiving a pin on said second plunger for guiding and limiting reciprocating movement of said second plunger in said second tube, and a recess in one side edge of said slot for receiving said pin when said second plunger is rotated at its closed circuit position to hold said contacts closed against said bias.

6. A switch comprising, separable contact means, a reciprooable operating member for actuating one of said contact means to open and closed circuit positions, said one contact means and operating member being biased for movement in a direction away from the other of said contact means to an open circuit position, said operating member'and movable contact means being normally free to move to closed circuit position upon application of operating force to said member suflicient to overcome said bias and being free to return to open circuit position under the influence of said bias upon removal of said operating force, means providing for over-travel of said operating member with respect to said contact means in the circuit closing direction and beyond the position it occupies when said contact means are first engaged, means responsive to movement of said member in another direction when at a position where said contact means are in engagement for holding said member at such position against movement by said bias, and cam means cooperating with a part of said member during over-travel thereof for releasing said holding means for reciprocal movement by moving said operating member in a direction opposite said other direction.

GORDON S. LEY.

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

UNITED STATES PATENTS Number Name Date 1,309,840 Bramming July 15, 1919 1,394,398 Benjamin Oct. 18, 1921 2,132,428 Meuer Oct. 1'1, 1938 2,156,443 Zook May 2, 1939 2,303,516 Von Mehren Dec. 1. 1942 2,389,259 Horlacher Nov. 20, 1945.

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