US3175421A

US3175421A - Adjustable cam mechanism

Info

Publication number: US3175421A
Application number: US24195A
Authority: US
Inventors: James P Watson
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-04-02
Filing date: 1960-04-01
Publication date: 1965-03-30
Anticipated expiration: 1982-03-30

Description

J. P. WATSON ADJUSTABLE CAM MECHANISM Original Filed April 2, 1956 I A 2K 4 g; x in March 30, 1965 6 m H 4 6 2 a A 2 H W y H M fix a, 7 2

United States Patent Ofitice 3,175,421 Patented Mar. 30, 1965 3,175,421 ADJUSTABLE CAM MECHANISM James P. Watson, Whittier, Calif.

(59 Waterway Road, Waterway Village, Jupiter, Fla.) Original application Apr. 2, 1956, Ser. No. 575,467, new

Patent No. 2,964,602, dated Dec. 13, 1960. Divided and this application Apr. 1, 1960, Ser. No. 24,195

3 Claims. (Cl. 74-568) The present invention is a division of copending application Serial No. 575,467 filed April 2, 1956, now Patent No. 2,964,602 in the name of James P. Watson for Snap Acting Mechanism.

The invention relates to an improved adjustable cam mechanism which, although to be described in conjunction with the particular snap acting leaf spring electric switch mechanism of the parent application, has general utility.

It is an object of this invention to provide an adjustable cam mechanism of simple structure having a minimum number of separate parts.

It is another object of this invention to provide a cam mechanism assembly as above wherein a number of such assemblies may be ganged together for operation from a single shaft.

It is another object of this invention to provide a cam actuating mechanism in which the cam may be readily adjusted on its operating shaft without the necessity of opening the housing or casing of the mechanism.

It is another object of this invention to provide a cam mechanism including a rotary cam and cam follower of such design that the cam follower attains a predetermined operating position at a given shaft position irrespective of the direction of rotation of the cam actuating shaft.

Inaccordance with these and other objects which will become apparent hereinafter, preferred forms of the present invention will now be described in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view partially broken away illustrating one form of an adjustable cam arrangement constructed in accordance with the present invention;

FIG. 2 is a partial section of the cam adjusting means shown in FIG. 1 with cam 69 rotated 90 degrees and worm threads 92 engaged with worm wheel teeth 91 FIG. 3 is a perspective view of one of the cams forming a portion of the switch operating mechanism;

FIG. 4 is a fragmentary cross section of earns 69 and 76 from FIG. 1;

FIG. 5 is a section similar to FIG. 4 illustrating a modification of this portion of the mechanism.

As noted above, the improved adjustable cam mechanism of the invention will be described in one embodiment in conjunction with the snap acting switch of copending application Serial No. 575,467 new Patent No. 2,964,602. That switch, as illustrated in FIGS. l-5, includes a leafspring 36 which has a pair of electric contacts 54 and 56 mounted on its opposite sides. These contacts make and break in selective engagement with two respective pairs of fixed contacts 57, 61 and 58, and a further stationary contact (not shown).

A shaft 39 is rotatably mounted in the housing 62 of the switch and is attached to the lower end of the leaf spring 36. The upper end of the leaf spring 36 is attached to a rotatable shaft 47 which is pivotally mounted to a frame cross piece 44 by a pivot mounting 51.

The means for pivoting or rotating the shaft 39 clockwise as seen in FIG. 1 comprises an arm 67 secured to the shaft 39 and extending transversely thereof. At the end of the arm 67 is a ball 68 which is engaged by a rotating cam 69 mounted to be rotated by a shaft means 71.

The cam actuating mechanism for the shaft 39 is shown in cross section in FIG. 4. As shown therein, the shaft means 71 consists of a center shaft which is splined to the interior of a sleeve 73. The cam 69 is frictionally mounted over the sleeve 73 so as to be adjustable thereon, but to be relatively fixed with respect thereto during normal operation of the switch.

The cam 69 is made of somewhat resilient material and is split as shown at 74 so that it may be forced over the sleeve 73 and retained in tight frictional engagement therewith through the resiliency of the cam material.

The cam 69 is one of a pair of cams 69 and 76, the cam '76 also being frictionally mounted on the sleeve 73 axially adjacent the cam 69, as shown in FIG. 4. The cam 76 acts upon a ball 77 formed on the end of another operating arm 78 projecting from the shaft 39 opposite to and in alignment with the arm 67. The cam 69 thus serves to pivot the shaft 39 in a clockwise direction to snap the leaf 36 to the right, and the cam 76 serves to pivot the shaft 39 in a counter-clockwise direction to snap the leaf 36 to the left. By the use of the two arms 67 and 78 with their respective ope-rating cams, no biasing spring is necessary and the leaf 36 remains firm in one position or the other until it is positively driven out of that position by cam action.

The sleeve 73 extends from one wall of the housing 62 to the other wall as shown in FIG. 4 and the axial bore extends clear through the sleeve 73 to permit the shaft 72 to pass completely through the housing 62 if desired. In this way, several housings may be placed side by side with the respective sleeves 73 in alignment and may all be driven from a single shaft 72 passing through or into each of the sleeve 73. To improve tolerance when this type of gauging is employed, the splines or keys 81 ex.- tending inwardly in the bore 79 of the sleeve 73 occupy only the center portion of the sleeve 73 as shown in FIG. 4, so that the spline connection between the shaft 72 and the sleeve 73 is limited to the center of the sleeve. Thus by providing clearance between the shaft 72 and the bore 79, misalignment tolerance is made available in the gauging of several switches together.

Since the leaf 36 is rocked back and forth by the two arms 67 and 78, it will be readily seen that if the two earns 69 and 76 were to be adjusted until they coincided angularly, the mechanism would jam, since there would be simultaneous pressure on the shaft 39' both clockwise and counterclockwise. In order to preclude such relative angular adjustment between the earns 69 and 76, intercngaging stop means between the two cams are provided in the form of arcuate shoulders 82 formed on the respective adjacent faces of the two cams 69 and 76. These shoulders preclude such cam adjustment as would cause jamming in operation.

In use of the switch mechanism of this invention, it is often desirable to be able to adjust the particular point in rotation of the shaft means 71 at which the leaf snaps to the right and also the point at which it snaps to the left. It is for this purpose that the cams 69 and 76 are adjustably, although frictionally, secured to the sleeve 73. In order to rotationally adjust the earns 69 and 76 on the sleeve 73, without having to open the housing 62 in any way, a worm shaft 83 is provided having on one end a ball 84 which is mounted in a socket 86 formed in the bottom wall of the housing 62. The socket 86 communicates with the interior of the housing 62, as shown at 87, in order to allow the worm shaft 83 to project into the vicinity of the earns 69 and 76 and also communicates with the exterior of the housing 62 as shown at 88 in order to allow a wrench 89 to be engaged in a corresponding socket formed in the ball 84.

Each of the cams 69 and 76 is provided with a worm Wheel having teeth 91 preferably formed integral with the cam, and the worm shaft 83 is likewise provided with threads 92 for engaging selectively the teeth 91 on the cams 69 or 76. The universal mounting of the worm shaft 83 in the socket 86 permits it to be engaged selectively with either the teeth 91 on the cam 69 or those on the cam 76, or alternatively to be disengaged from both of the worm wheels as shown in FIG. 1. The worm shaft 83 is normally biased completely out of engagement with either cam by a leaf spring 35.

Following insertion of a wrench 89, one may pivot the shaft 83 into position opposite the desired cam 69 or 76 and then pivot the threads 92 into engagement with the worm wheel teeth 91. While maintaining the worm shaft 83 in this position, rotation of the wrench 89 then causes rotation of the selected cam until the desired adjustment is achieved. Either cam may be thus adjusted independently at will.

The ball and socket mounting of the worm shaft 83 leaves the housing 62 essentially unbroken while still permitting ready external adjustment of either of the cams. The worm thread 92 is shown in engagement with the cam 69 in FIG. 2.

A variant of the coupling between the shaft means 71 and the cams, for example the cam 69, is shown in FIG. 5. In this variant, an outer sleeve 75 is fitted loosely over the sleeve 73a which is splined to the center shaft 72. Thus the outer sleeve 75 becomes, in effect, part of the operating shaft means71a. The

cams

69a and 76a are frictionally mounted over the outer sleeve '75. Outer sleeve '75 is coupled rotatively to sleeve 73a only by a radial tab 108 which extends into a recess or hole 109 in the sleeve 75. The tab and recess thus form a stop means limiting the free rotative movement between outer sleeve '75 and sleeve 73a. There is thus introduced into the system a deliberate but predetermined backlash between the shaft 72 and the

cams

69a and 76a. This backlash, when properly proportioned, has the effect of causing each cam for example the cam 69a to effect snapping of the leaf '56 from one position to the other at the same position of the shaft 72, irrespective of whether the cam 69:: approaches the ball 68 in a clockwise or counter clockwise direction.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be afforded the full scope of the claims.

What is claimed is:

1. Cam actuating mechanism comprising a housing having an exterior wall with a socket formed therein, a shaft journalled within said housing, a first actuating cam frictionally and coaxially mounted on said shaft, a second actuating cam frictionally and coaxially mounted on said shaft, first worm Wheel means mounted on said first actuating cam, second Worm wheel means mounted on said second actuating cam, a normally disengaged worm means including a shank having a ball thereon universally secured in said socket and adjustable from the exterior of said housing, said ball and socket forming a seal, where by said worm means may be selectively engaged with said first worm wheel means or with said second worm wheel means selectively to adjust the angular position of said first actuating cam on said shaft and the angular position of said second actuating cam on said shaft without requiring penetration of said housing.

2. The cam actuating mechanism defined in claim 1 and which includes resilient means biasing said worm means out of engagement with said first worm wheel means and said second worm wheel means.

3. The cam actuating mechanism defined in claim 1 in which said shaft is tubular and which includes an inner shaft mounted loosely and coaxially within said shaft and loosely coupled thereto thru the intermediacy of a radial tab formed on said inner shaft and residing within a slot formed in said shaft, said slot having a greater circumferential dimension than said tab, said coupling introducing the correct amount of rotational slack between said inner shaft and said shaft to cause said actuating cams to produce identical actuations in response to the same inner shaft position attained by either direction of rotation of said inner shaft.

References Cited by the Examiner UNITED STATES PATENTS 475,379 5/92 Baker 7457 712,366 10/02 Donoughe 74-57 1,169,957 2/16 Henry 74-568 X 2,305,540 12/42 Lowther 74-568 2,387,097 10/45 Somes 74568 2,554,545 5/51 Winder 74568 2,594,911 4/52 Goff 74-568 2,903,528 9/59 Kahn 74568 X FOREIGN PATENTS 35,901 12/29 France. 26,555 8/06 Great Britain. of 1905 BROUGHTON G. DURHAM, Primary Examiner.

SAMUEL SPITMAN, Examiner.

Claims

1. CAM ACTUATING MECHANISM COMPRISING A HOUSING HAVING AN EXTERIOR WALL WITH A SOCKET FORMED THEREIN, A SHAFT JOURNALLED WITHIN SAID HOUSING, A FIRST ACTUATING CAM FRICTIONALLY AND COAXIALLY MOUNTED ON SAID SHAFT, A SECOND ACTUATING CAM FRICTIONALLY AND COAXIALLY MOUNTED ON SAID SHAFT, FIRST WORM WHEEL MEANS MOUNTED ON SAID FIRST ACTUATING CAM, SECOND WORM WHEEL MEANS MOUNTED ON SAID SECOND ACTUATING CAM, A NORMALLY DISENGAGED WORM MEANS INCLUDING A SHANK HAVING A BALL THEREON UNIVERSALLY SECURED IN SAID SOCKET AND ADJUSTABLE FROM THE EXTERIOR OF SAID HOUSING, SAID BALL AND SOCKET FORMING A SEAL, WHEREBY SAID WORM MEANS MAY BE SELECTIVELY ENGAGED WITH SAID FIRST WORM WHEEL MEANS OR WITH SAID SECOND WORM WHEEL MEANS SELECTIVELY TO ADJUST THE ANGULAR POSITION OF SAID FIRST ACTUATIN CAM ON SAID SHAFT AND THE ANGULAR POSITION OF SAID SECOND ACTUATING CAM ON SAID SHAFT WITHOUT REQUIRING PENETRATION OF SAID HOUSING.