US 3712965 A
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Jam-23, 1973 T. B. DALTON 3,712,965
SWITCH OPERATING MECHANISM FOR LIMIT SWITCHES Filed May 10, 1971 INVENTOR THOMAS B. DALTON 37 w, @4474 g Windham,
ATTORNEYS United States Patent US. Cl. 200--17 R 4 Claims ABSTRACT OF THE DISCLOSURE A mechanism for operating a drum switch which includes a switch actuator movable between a first and a second position. A limit arm is rigidly mounted and aligned with the actuator. A lever is pivotally mounted on the limit arm with a spring biasing means further mounted between the limit arm and the lever. The lever is placed into abutment with the switch actuator responsive to movement of the switch to provide a first engagement between the actuator and the lever to depress the biasing means and subsequently to move the actuator from its first to its second position by the lever responsive to the return of the biasing means to its initial condition.
BACKGROUND OF THE INVENTION The present invention relates to a switch actuating means for an electrical switch, particularly one of the drum type. In manually operated drum switches, particularly those with a relatively large number of contacts such as those used for three phase motors or for reversing motors, there is a problem due to the occasional failure of all the contacts to open or to close simultaneously, which failure can result in contact arcing and motor burnout if a switch is left in an intermediate position for an excessively long period of time. Drum switches have detent mechanisms which are prone to becoming stuck between detent positions and, if they are moved too slowly, they can cause some contacts to be opened and others to be closed when all should be opened or closed at the same time.
The present invention makes provision for a switch operating mechanism which is particularly effective to prevent slow drum switch contact and break and indeed provides an improvement that may be used in conjunction with any other electrical switches which may oifer similar problems with respect to arrested movement of the switch actuator between its several positions.
BRIEF DESCRIPTION OF THE DRAWINGS The following is a brief description of the drawings in which like numerals are used to designate like parts of the embodiment of the invention as they may occur in the several views:
FIG. 1 is a diagrammatic illustration of the invention, partly in section, showing the switch as it is moved from its initial positon;
FIG. 2 is a view similar to FIG. 1 in which the switch has been moved to provide a depressing contact between the switch actuator and the lever; and
FIG. 3 is a view similar to FIGS. 1 and 2 in which the switch actuator has been operated through the back movement of the lever and its associated spring.
DETAILED DESCRIPTION OF THE DRAWINGS With reference to FIG. 1, an electrical contactor drum switch is shown, which switch includes an actuator 12 movable between a first neutral or inactive position such as indicated by dash line configuration, and a lower active position indicated by solid line. The switch operator 12 may be of the manually operated type and typically includes a relatively large number of contacts. Included at the end of the switch actuator 12 is an enlarged knob 14. The switch 10 is further mounted on a movable member, indicated generally by the numeral 16, at the left side of the switch 10. A post 18 is shown in part, which post in the present instance is mounted in a stationary position. Fixed to the post 18 by a fastener 19 is a limit arm 20 which is placed in alignment with the end knob 14 of the switch actuator 12. A lever 21 is pivotally mounted proximate the right hand end of the limit arm 20 by a pin 22. In addition, a biasing means embodied as a compression spring 24 is mounted between the lever 21 and an opposed bore 26 formed in the limit arm 20. It will be seen that the lever 21 is normally maintained upwardly due to the action of the compression spring 24, this repre senting the position of the lever 21 prior to its contact with the switch actuator 12. While the present embodiment employs a compression spring, it will be understood that other resilient energy storing devices may be used as the biasing means.
In the illustrated embodiment, the switch 10 is shown attached to a movable member for controlling, for example, its distance of travel, while the limit arm 20 and the switch actuator lever 21 are stationary. It will be understood that this arrangement may be reversed so that the actuating assembly, including the arm 20, may be attached to a movable object, while the switch is held stationary and actuated responsive to the movement of the arm 20. In either case, the basic method of operation of the switch operating mechanism remains the same.
In FIG. 1, the movement of the member 16 and of the switch 10 is downward as indicated by the arrow. FIG. 2 shows a somewhat further advanced movement of the switch 10 in such a manner that the actuator 12 through the knob 14 has depressed the lever 21 from its normally upstanding position to a position in which the lever 21 lies substantially fiat against the upper surface of the limit arm 20. The compression spring 24 is biased downwardly in a state of compression. Thus far, actuating lever 12 has not been moved from its detented position, that is, from the lower one indicated in FIG. 1. Because of the stored energy in the spring 24, the lever 21 is then urged upwardly and causes the switch actuator 12 to flip upwardly from its lower detented position to a neutral position as it is next shown in FIG. 3. With switch actuator =12 returned to its neutral position, it is now readied for further manual operation to an upward position as indicated in dash line form. It will be appreciated that a limit arm and associated lever 21 can be positioned at either or both ends of the switch 10 and movable member 16 so that automatic switching operation can be provided at either extreme of movement of the movable object 16.
It will be seen that I have provided a new and improved switch actuating mechanism. Various modifications to the illustrated embodiment may be made by those skilled in the art without departing from the general spirit of the invention.
1. A switch operating mechanism for a switch of the detent type, said switch having a switch actuator movable between a first detent position and a second detent position for operating it, wherein the improvement comprises: an arm member relatively reciprocally axially movable toward and away from said switch actuator,
a lever pivotally mounted to said arm in a position to move into and out of engagement with said switch actuator upon reciprocal movement of said arm member,
means biasing said lever to a pivoted position outwardly toward said switch actuator, and
means limiting pivotal movement of said arm in a direction away from said switch actuator whereby relative movement of said arm member and said switch actuator produces initial depression of said lever against said biasing means until said limit position of said lever is reached whereupon said actuator is moved by said leverfrom said first position toward said second position, said biasing means urging said lever member outwardly again to impart force to said arm.
2. The combination as set forth in claim 1 wherein said lever is pivotally mounted proximate its one end to said arm member and wherein said biasing means comprises a compression spring operatively connected between the other end of said lever and an adjacent portion of said arm member.
3. A switch mechanism for a switch movable between at least two positions and including means for actuating said switch comprising:
a lever and means pivotally mounting said lever between a first and a second pivoted position,
biasing means urging said lever toward said first position,
said lever and said switch being relatively movable toward and away from a position in which said lever and said switch are in engagement and said switch is moved from one of its positions to the other of its positions,
said biasing means urging one end of said lever toward said first position and in a direction toward engageing an arm and wherein said lever is pivotally mounted proximate one end of said arm and wherein said biasing means comprises a compression spring operatively connected between the other end of said lever and an adja cent portion of said arm.
References Cited 7 UNITED STATES PATENTS 2,198,469 4/ 1940 Woodward 200-17 'R X 2,593,670 4/ 1952 Grikscheit 200-47 3,602,673 18/ 1971 Morin et al 20017 R X 2,984,720 5/1961 Fisher 200-172 A X 2,817,725 12/ 1957 Rochfort et a1. 20047 3,248,956 5/ 1966 Kuhn 20047 X JAMES R. SCOTT, Primary Examiner US Cl. X.R.
ZOO-47,153 T, 172 R; 74-96