US2247080A - Switch operating mechanism - Google Patents

Description

June 24, 1941. w. w. BROWN SWITCH OPERATING MECHANISM Filed 001;. 5i, i940 Invent?Br-: Walter* W own,

His Attorne g.

Patented June 24, 1941 SWITCH OPERATING MECHANHSM Walter W. Brown, Erie, Pa., assignor to General ElectricCompany, a corporation of New York Application October 31, 1940, Serial No. 363,763

(Cl. lat-568) 12 Claims.

My invention relates to switch operating mechanism and is particularly applicable to switch operating mechanism provided with a plurality of cams, such as used in conjunction with electric motor controllers. of the drum .ty-pe.

Where a plurality of cams are mounted along the length of a single shaft it is common practies to mount the cams upon a portion of the shaft having a rectangular cross-section. While this is a simple and effective device for fixing the cams against rotation, it presents considerable inconvenience whenever it is desired to change the angular setting of any one or more of the cams. For example, it is desired to convert a selected switch from normally closed to normally open, it is necessary to change the angular position of its cooperating cam with respect to the shaft. In order to angularly adjust a switchopcrating cam of conventional design it is first necessary to remove from the shaft that cam and all other cams lying between it and the end of the. assembly. This inconvenience is particularly undesirable in certain applications where it is necessary frequently to change the normal position of only a certain selected few of a plurality of cam operated switches. In such applications, while it is advantageous for reasons of constructional simplicity and durability to retain the square-shaft type of mounting for the cams, it is very desirable to have means provided for angularly adjusting the selected cams without the necessity of longitudinally displacing them any substantial distance.

Accordingly, it is an object of my invention to provide mounting means for a switch operating cam permitting angular adjustment of the cam on its shaft.

It is a further object of my invention to provide means for mounting a switch operating cam upon a shaft of non-circular cross-section while permitting angular adjustment of the cam with respect to the shaft without substantial longitudinal displacement.

It is characteristic of my invention that one or more cams constructed in accordance therewith may be mounted on a common shaft with one or more non-adjustable cams and may be adjusted without removing any cam from the shaft.

To the attainment of the foregoing and other objects and advantages my invention is preferably embodied in the detailed construction to be hereinafter more fully described and claimed, and is illustrated in the accompanying drawing in which Fig. 1 is an exploded perspective view of the component parts of my cam assembly; Fig.

2 is a cross-sectional view taken through the center line of the cam shaft and showing the details of the cam and bushing assembly; and Fig. 3 is a perspective View of a cam shaft provided with one cam constructed in accordance with my invention and a plurality of conventional nonadjustable cams.

According to my invention an externally threaded bushing carrying an internally threaded cam is mounted upon'a shaft of non-circular cross-section and means are provided for securing the cam to the bushing in a plurality of angularly spaced positions.

Referring now to the drawing, the numeral Iii represents, a shaft of the type upon which my improved cam is adapted to be mounted. As shown in Figs. 1 and 3, the shaft it consists of one or more end portions of circular cross-section and a cam-supporting portion I! of noncircular cross-section, shown by Way of example as rectangular. As hereinbefore mentioned, cams such as l2 and it of Fig. 3 may be provided with central apertures of the same configuration as the cross-section of the portion ll of the shaft and may be mounted directly upon this portion of the shaft.

Referring now particularly to Fig. 1, my invention comprises a bushing it provided with a rectangular or other non-circular central aperture E5 of the same configuration as the cross-section of the shaft portion H upon which it is to be mounted. The bushing id is preferably of electrical insulating material as indicated on the drawing. The external cylindrical surface of the bushing i4 is threaded, as at It, and is adapted for cooperation with internal threads ll of a circularly apertured cam it. The cam i8 is likewise preferably composed of electrical insulating material.

For the purpose of securing the cam Hi to the bushing i l in any one of a plurality of angularly spaced positions the bushing M is provided with a plurality of recesses 59. From Figs. 1 and 2 it may be seen that each of the recesses 59 is provided with a base portion fill forming a seat for a locking spring 25. Each locking spring 25 includes a diagonally extending portion 26. As best shown in Fig. 2, the springs 25 are not planar figures, but the central diagonally extending portions 28 are bowed upward so that when placed in the recesses 19 the portions 26 of the springs are raised above the base portions 20 of the recesses. It will be understood, of course, that I do not wish to be limited to the particular number of recesses l9 and springs 25 which I have shown and described, but that any desired number of recesses I9 and springs 25 may be located in angularly spaced positions about the bushing I l. For cooperation with any selected locking spring 25 a set screw 27, threaded into a radial aperture 28 of the cam I8, is provided. An end portion 29 of the set screw is provided with one or more diametrical slots 38 of sufiicient width to embrace the portion 26 of any spring 25.

In looking my improved cam to a shaft procomes into contact with the bowed-up portion 26 of the spring 25. Continued rotation of the set screw 2'! will begin to depress the portion 26 of the spring 25. After the portion 26 of the spring has been slightly depressed it will spring upward into locking engagement with the first diametric'al slot 3|] which is brought into alignment therewith. The set screw 21 may thus be screwed down until it is sufiiciently tightly locked by the spring 25.

In order to provide for the slight longitudinal displacement of the cam I8 as it is rotated upon the bushing I4, the bushing I4 is preferably larger in longitudinal dimension than the cam I8, and the recesses I9 have .a longitudinal dimension somewhat greater than th diameter of the set screw 21.

When the cam I8 is fixed in any one of its possible positions, longitudinal displacement of the cam is prevented by engagement of the threads I6 of the bushing I4 with the threads I! of the cam I8, while angular displacement of the cam is pervented by engagement of the sides 3| of the spring with the sides of the recess 9- If the spring 25 should not fit snugly into the recess I9, engagement of the end portion 38 of the set screw 21 with the sides of the aperture will prevent any substantial angular displacement of the cam.

Fig. 3 shows a switch operating mechanism constructed in accordance with my invention and mounted on a shaft I0 which also carries a plurality of cams l2 and I3. All the cams I8, I2 and I3 are mounted upon a non-circular section II of the'shaft II], but the cams I2 and I3 are fixedly mounted directly upon the ortion II while the cam I8 is adjustably mounted by means of the bushing I 4. It will, of course, be understood that Fig. 3 represents only a portion of a cam shaft assembly in which any desirednumber of my improved operating mechanisms are assembled in any desired positions among a plurality of conventional fixedly mounted cams such as l2 and I3.

Fig. 3 also shows a plurality of operating members or switch arms 32, 33 and 34 adapted to be positioned by the cams I2, I3 and I8 when the shaft II] is rotated. Since all the arms are similar, only the arm 32 has been shown in full. As illustrated, the .arm 32 is pivotally mounted upon a pin 35 and carries a movable contact 36 cooperating with a relatively fixed contact 37.

The operating arms 32 63 and 34 are preferably of electrical condflcting material and, being electrically in contact with the contacts 36 and 31, possess a voltage differing appreciably from ground potential. Since the cam shaft III is usually grounded, it will be observed that a potential gradient will exist along the surface of the cam I8 and the bushing I4. The length of insulating surface along this path is considerably greater in my operating mechanism than in the conventional cam assembly shown at I2 and I3 in Fig. 3. The length of the insulating surface in my operating mechanism is increased by two factors; first the end portions of the bushing I 4 which protrude beyond the side surfaces of the cam I8, and second, the threads IE on the bushing I4. By these means, then, the effect of electrical surface creepage, ordinarily disturbing in controllers of this type, is appreciably diminished.

While I have described a particular preferred embodiment of my invention by way of example, I wish to have it understood that I do not wish to be limited thereto, and I therefore contemplate y the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a switch operating mechanism, a plurality of operating members, a cam shaft, a cam non-rotatably mounted upon said shaft engaging one of said members, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface, an internally threaded operating cam mounted on said bushing and engaging one of said members, and means for locking said operating cam to said bushing in any one of a pillrality of spaced angular positions.

2. In a switch operating mechanism, a plurality of pivotally mounted operating members, a cam shaft, a plurality of cams non-rotatably mounted upon said shaft, each of said cams engaging one of said members, a bushing mounted upon said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spacad recesses, an internally threaded operating cam mounted upon said bushing and having a threaded aperture for the reception of a set screw, said operating cam engaging one of said members, and a set screw in said aperture for locking said operating cam to said bushing in any one of a plurality of predetermined spaced angular positions.

3. In a switch operating mechanism, a plurality of pivotally mounted switch operating members, a cam shaft, a plurality of cams non-rotatably mounted upon said shaft, each of said cams engaging one of said members, a bushing mounted upon said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spaced recesses, an internally threaded operating cam mounted upon said bushing and having a threaded aperture for the reception of a set screw, said operating cam being smaller in longitudinal dimension than said bushing and engaging one of said members, a set screw in. said aperture, and a locking spring positioned in each of said recesses for locking engagement with said set screw. 7 V

4. In a switch operating mechanism, a plurality of pivotally mounted switch operating arms, a cam shaft of non-circular cross-section, a plurality of cams non-rotatably mounted upon said shaft, each of said cams engaging one of said arms, a bushing of insulating material mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spaced recesses, a locking spring positioned in each of said recesses, an operating cam of insulating material mounted in threaded engagement with said bushing, said operating cam having a smaller longitudinal dimension than said bushing, and a set screw in said cam provided with a grooved end face and positioned for looking engagement with any one of said locking springs.

5. A cam assembly comprising a cam shaft, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface, an internally threaded cam mounted upon said bushing, a set screw connected to said cam, and a plurality of separate resilient locking means associated with said bushing and arranged selectively to engage said set screw to secure said cam to said bushing in any one of a plurality of predetermined spaced angular positions.

6. A cam assembly comprising a cam shaft, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spaced recesses, an internally threaded cam mounted upon said bushing and having a threaded aperture for the reception of a set screw, and a set screw in said aperture for locking said cam to said bushing in any one of a plurality of predetermined spaced angular positions.

7. A cam assembly comprising a cam shaft, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a'threaded cylindrical external surface provided with a plurality of angularly spaced recesses, an internally threaded cam mounted upon said bushing and having a threaded aperture for the reception of a set screw, a set screw in said aperture, and a locking spring positioned in each of said recesses for locking engagement with said set screw.

8. A cam assembly comprising .a cam shaft of non-circular cross-section, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a plurality of angularly spaced recesses in its external surface, a cam rotatably mounted on said bushing, and a set screw in said cam, a plurality of separate resilient locking means operatively associated with said recesses selectively to lock said cam to said bushing in any one of a plurality of predetermined spaced angular positions.

9. A cam assembly comprising a cam shaft of non-circular cross-section, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a plurality of angularly spaced recesses in its external surface, a cam rotatably mounted on said bushing, a set screw in said cam, and resilient locking means associated with said set screw and said recesses for fixing said cam to said bushing in a plurality of predetermined spaced angular positions.

10. A cam assembly comprising a cam shaft of non-circular cross-section, a bushing mounted on said shaft in fixed relation thereto, said bushing having a plurality of angularly spaced recesses in its external surface, a locking spring positioned in each recess, a cam rotatably mounted on said bushing, and a set screw in said cam positioned for locking engagement with any one of said springs.

11. A cam assembly comp-rising a cam shaft of non-circular cross-section, a bushing mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spaced recesses, a locking spring positioned in each recess, a cam mounted in threaded engagement with said bushing, and a set screw in said cam positioned for locking engagement with any one of said locking springs.

12. A cam assembly comprising a cam shaft of non-circular cross-section, a loushing mounted on said shaft in fixed angular relation thereto, said bushing having a threaded cylindrical external surface provided with a plurality of angularly spaced recesses, a locking spring positioned in each recess, a cam mounted in threaded engagement with said bushing, and a set screw in said a cam provided with .a grooved end face and posi-

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