US2964600A

US2964600A - Switch actuating mechanism

Info

Publication number: US2964600A
Application number: US659509A
Authority: US
Inventors: Marvin S Blemly; Adelbert J Schenk
Original assignee: Jervis B Webb Co
Current assignee: Jervis B Webb Co
Priority date: 1957-05-16
Filing date: 1957-05-16
Publication date: 1960-12-13
Anticipated expiration: 1977-12-13
Also published as: BE560266A; GB814583A; FR1181393A

Description

Dec. 13, 1960 M. s. BLEMLY ETAL 2,964,600

SWITCH ACTUATING MECHANISM Filed May 1a, 1957 2 Sheets-Sheet 1 izibzv/ Dec. 13, 1960 M. s. BLEMLY ET AL 2,964,600

SWITCH ACTUATING MECHANISM Filed May 16, 1957 2 Sheets-Sheet 2 INVENTORS MAAW/V o. 84 6/144 Y United States Patent C) SWITCH ACTUATIN G MECHANISM Marvin S. Blemly, Birmingham, and Adelbert J. Schenk, Huntington Woods, Mich., assignors to Jervis B. Webb Company, Detroit, Mich., a corporation of Michigan Filed May 16, 1957, Ser. No. 659,509

4 Claims. (Cl. 200-'47) This invention relates to an improved construction for mounting and actuating a switch elementparticularly a switch element of the sensitive push button type-to enable such' an element to be used in industrial applications.

Switch elements of the type mentioned are widely employed for limit switch uses, and in this application a need has existed for a satisfactory unit in which such a switch element can be mounted and actuated in response to the operation of moving components of machinery. Such a unit must impart the small amount of movement required for actuation of the switch element in response to contact between a moving machinery part and an actuating arm. Contact forces are large as are contacting movements relative to the amount of movement required for actuation of the switch element.

A number of constructions have been devised for such a unit. In general these include a housing in which the switch element is mounted, an actuating shaft joumalled in the housing with an actuating arm secured to a position of the shaft projecting from the housing, a cam carried by the shaft and a cam follower. Some means are included for actuating the switch element in response to movement of the cam follower.

The present invention offers a simplified arrangement of and relation between these elements which results in a greater degree of flexibility of the unit particularly in terms of the amount of permissible movement, direction of movement and over-travel of the actuating arm, and which will provide improved service life under the conditions of use outlined above.

In the improved construction the cam follower is pivotally mounted in the housing and includes a follower element mounted to contact the periphery of the actuating cam which is formed with a notch to receive the follower element and thereby define one position of the follower arm. Spring means are employed to bias the follower arm into contact with the cam periphery and as a result the follower arm acts to define one position of the actuating-cam when the element on the follower arm is in engagement with the notch thereof. A centering spring is employed to urge the actuating shaft, actuating arm and cam to the centered position defined by the actuating arm. Preferably, this spring is a coil type wound about the shaft and has its ends formed to extend-radially from the center of the shaft to provide a pair of action and reaction arms. A pair of members are provided, each being positioned to contact either of the spring arms. One of these members is fixedly mounted in the housing and the other is rotatable with the actuating shaft. As a result these members and centering spring will return the shaft and cam to a centered position for retention therein by engagement by the follower element on the follower arm and the notch in the cam.

Preferably, one of the centering spring actuating mem bers is secured to the cam and the other to the housing adjacent the cam and these members are relatively positioned in spaced relation to the center of the actuating shaft and are in radial alignment with the center of the shaft when the cam is in its centered position.

The housing is made to provide very rigid support for the actuating shaft and for the actuating arm.

An improved mounting of the actuating arm on the end of the shaft is also provided so that the position of the arm relative to the centered position of the shaft and cam can be positively fixed in a great number of positions.

A presently preferred constructional example of the invention is shown in the accompanying drawings which comprise the following views:

Fig. 1, a plan view of the construction with the housing cover being broken away;

Fig. 2, a sectional elevation taken on the line 22 of Fig. 1;

Fig. 3, an end elevation of the unit shown in Fig. 1;

Fig. 4, an enlarged sectional detail taken on the line 44 of Fig. 2; and

Fig. 5, a sectional detail taken on the line 55 of Fig. 4.

Referring to Figs. 1-3, the unit includes a housing having a base 10 and a cover 11. A switch element 12 and an actuating button 13 is secured to the base by screws 14.

The base 10 includes a thickened, counterbored portion 16, mounting a pair of

ball bearings

17 and 18 which support an actuating shaft 19. The

bearings

17 and 18 are located by an intermediate spacer 20.

The inner-end of the shaft 19 projects beyond counterbored portion 16 and a circular cam 23 is secured thereto. A coil centering spring 21 is mounted on the shaft 19 between the cam and inner-face 22 of the counterbored portion. This spring is formed so that its

ends

24 and 25 extend radially outwardly from the center of shaft 19. These spring ends function as action and reaction arms in combination with a member 26 secured to the cam and projecting toward the counterbored portion of the hous-- ing and a fixed member 27 mounted in the counterbored portion. As can be seen in Fig. 1, these members 26 and. 27 are mounted in spaced relation to the center of theshaft 19 and are radially aligned with the center of the shaft with the parts in the position shown. A plate 28 is secured to the underside of the cam (Fig. 1) and acts as a stop in combination with the fixed member 27.

This position will be referred to as the centered position of the components. It is additionally defined by engagement between a roller follower 30 carried by an actuating arm 31 and a notch 32 formed in the periphery of cam 23 on the approximate radius of the roller follower 30. The actuating arm is secured to a collar 34 which is: pivotally mounted on a screw 35 engaging a boss 36 of the housing. The arm includes an L-shaped actuating tab 83 which is secured to the arm and projects downwardly to engage the push button 13 of the switch. A coil spring. is mounted on the collar 34 and normally urges the roller follower 30 into contact with the periphery of the cam 23 through the reaction of one end 40 of the spring against the housing and the other end 41 of the spring against the tab 38.

The roller follower 30, notch 32 and the actuating cam and location of the tab 38 are inter-related with two considerations in mind, first, to impart a proper amount of actuating movement to the switch push button 13 upon movement of the roller follower out of the notch 32 and onto the circular cam periphery; and second, to give sufiicient depth of engagement of the roller follower 30 in the notch 32 so that the follower arm will act to retain the actuating cam 23 and shaft 19 in normal centered position.

An actuating arm 44 is removably secured by set screws 47 to an arm mounting member 45 which has a hub 46 mounted on the shaft 19 for free rotation. The hub is held on the shaft by a snap ring 48. The hub includes a projecting circular portion 49 equipped with teeth 50' around the outer circumference thereof. A square drive 52 (Fig. 5) is provided on the end of shaft 19 and a locking element 53 engages this square drive and is held on the end of the shaft by a screw 54. The locking element has an inwardly projecting portion 56 (Fig. 5) which has internal teeth 57 to engage the external teeth 50 of the hub 46. This arrangement offers a multiplicity of fixed radial positions of the actuating arm 44 on the shaft 19. For example, if the hub 46 is provided with 25 external teeth 50 and the lock member 53 can be mounted in any one of four positions on the square drive 52, a total of 100 positions of the actuating arm are provided. In other words, the setting of the arm may be changed in increments of approximately 3% degrees.

While preferred embodiments have been described above in detail, it will be understood that numerous modifications might be resorted to without departing from the scope of our invention as defined in the following claims.

We claim:

1. A switch construction of the type comprising a closed housing, a shaft journalled therein with at least one end of the shaft projecting from the housing and carrying an actuating arm, a cam mounted on the shaft in the housing, a cam follower arm pivotally mounted in the housing and a switch element having an actuating button operable by movement of the follower arm; characterized by a roller mounted on free end of the follower arm for contact with the periphery of the cam, said periphery being generally circular and having an arcuate notch formed therein on the approximate radius of said follower arm roller, spring means normally urging said follower arm into contact with said cam periphery whereby said follower roller acts to retain said cam in centered position when engaged in said notch, switch actuating button contacting means carried by said follower arm at a location between the pivot axis thereof and said follower roller, a coil centering spring carried by said shaft axially adjacent said cam, the ends of said spring forming a pair of action and reaction arms extending radially of said shaft, and a pair of action and reaction members positioned between said spring ends in spaced relation on a radial line from the center of said shaft, one of said members being mounted on said cam and the other being fixedly carried by said housing whereby said centering spring will return said shaft and cam to centered position for retention by said follower arm after rotation of said actuating arm in either direction.

2. A switch construction of the type comprising a closed housing, a shaft journalled therein with at least one end of the shaft projecting from the housing and carrying an actuating arm, a cam mounted on the shaft in the housing, a cam follower arm pivotally mounted in the housing and a switch element operable by movement of the follower arm; characterized by a follower element mounted on said follower arm for contact with said cam, said cam having a circular periphery with a notch formed therein to receive said follower element and define one position of said follower arm, spring means biasing said follower arm into contact with said cam whereby said follower arm acts to define one position of said cam when the follower element engages the notch thereof, a centering spring carried by said shaft with the ends of said spring forming a pair of action and reaction arms extending radially of said shaft, a pair of members each positioned to contact either of said arms, one of said members being fixedly carried by said housing and the other being rotatable with said shaft whereby said members and centering spring will return said shaft and cam to the centered position defined by engagement of said follower element in the notch of said cam after movement of said actuating arm to produce rotation of said shaft in either direction, and said housing having a counterbored portion containing a pair of bearings for supporting said shaft, one end of said shaft projecting into said housing beyond said counterbored portion thereof, said cam being secured to the inner end of said shaft, said centering spring being mounted on said shaft between said cam and said counterbored housing portion, one of said spring contacting members being secured to said cam and projecting toward the housing and the other of said spring contacting members being secured to the housing and projecting toward said cam, said two members'being relatively mounted in spaced relation to the center of said shaft.

3. A switch construction according to claim 2 wherein said members are in radial alignment to the center of said shaft when said cam is in the said centered position.

4. A switch construction of the type comprising a closed housing, a shaft journalled therein with at least one end of the shaft projecting from the housing and carrying an actuating arm, a cam mounted on the shaft in the housing, a cam follower arm pivotally mounted in the housing and a switch element having contact means operable by movement of the follower arm; characterized by a follower element mounted on said follower arm for contact with said cam, said cam having a notch formed therein to receive said follower element and define one position of said follower arm, spring means biasing said follower arm into contact with said cam whereby said follower arm acts to define one position of said cam when the follower element engages the notch thereof, means carried by said follower arm for engaging said switch element contact means, a centering spring carried by said shaft with the ends of said spring forming a pair of action and reaction arms extending radially of said shaft, and a pair of members each positioned to contact either of said arms, one of said members being fixedly carried by said housing and the other being rotatable with 'said shaft whereby said members and centering spring will return said shaft and cam to the centered position defined by engagement of said follower element in the notch of said cam after movement of said actuating arm to produce rotation of said shaft in either direction.

References Cited in the file of this patent UNITED STATES PATENTS Short et al Mar. 24, 1959