US3459903A - Rotary cam actuated switch operating plate in a high current switching device - Google Patents

Description

L, .RlcHA soN 3,459,903'L 'ROTARY CA c u TEn'swI c OPERAT PLATE 1N A H CURRENT swI'rcHING n CE Filed Sept. 7, 1967- v United States Patent O U.S. CI. 200-6 7 Claims ABSTRACT OF THE DISCLOSURE A high current sequential switching device for use in a rotary switch in which a shaft for operating the rotors of a plurality of switch sections is rotatably mounted in a frame. A fixed contact member is mounted on the frame radially outwardly from the shaft and a contact carrying leaf spring is spaced radially from the shaft and is biased into engagement with the fixed contact member. A cam y member is pivotally mounted on the frame at a point spaced radially from the shaft and angularly from the contact carrying leaf spring. Detent means is carried by the shaft for intermittently pivoting the cam member against the leaf spring in response to rotation of the shaft to intermittently move the contact on the leaf spring out of engagement lwith the fixed contact member.

Background of the invention It is often desirable to provide for the switching of a higher current than is normally used in rotary switches, as a function of the rotation of the rotary shaft. However, the current capacity of the conventional rotary switch is limited by the size of the rotor and stator contacts, and in most rotary switches the space limitations for the overall switch govern the size of the contacts. Therefore, with the Wide use of small rotary switches, the current capacity is restricted. This invention provides a means for overcoming the limitation on the current capacity of such rotary switches.

Summary of the invention A principal object of this invention is to provide means to allow switching of a higher current than is normally used in rotary switches.

Another object of this invention is to provide, in a rotary switch, a cam-operated leaf-type switch which may be operated in increments the same as, or different from but in multiples of the detent increments of the rotary switch.

A further object of this invention is to provide a means as set forth in the preceding paragraph which is operated as a function of rotation of the rotary shaft of the switch.

Still another object of this invention is to provide, in a rotary switch, a contact carrying leaf spring which is normally biased into engagement with a fixed contact carrying member, a cam plate pivotally mounted on the switch frame and detent means on the rotary shaft of the switch for intermittently pivoting the cam plate against the leaf spring in response to rotation of the shaft to move the contact on the leaf spring out of engagement lwith the fixed contact.

Description of the drawings FIG. 1 is a fragmentary elevation view of a portion of a rotary switch embodying the invention;

FIG. 2 is a sectional view taken generally along the line 2 2 of FIG. 1, with a portion cut away for illustration; and

FIG. 3 is a sectional view taken generally along the line 3--3 of FIG. 2, with the rotary shaft in elevation.

3,459,903 Patented Aug. 5, 1969 ICC Detailed description of the invention The invention is illustrated herein as embodied in a rotary switch to allow switching of a higher current than is normally permitted. FIG. 1 shows a portion of a conventional rotary switch which may have one or more switch sections, one of which is generally indicated at 10. The switch sections are spaced axially along a rotary shaft 12. In a known manner the shaft 12 has a plurality of angular detent positions defining intermittent rotational positions for the shaft. The switch sections and rotary shaft are mounted on the switch frame which includes strut screws 14a, 14b extending generally parallel to the rotary shaft 12 for supporting stators 16 of the respective switch sections 10. `Cylindrical spacers 18 surround strut screws 14 for positioning the switch sections axially along the frame. As is known, a rotor (not shown in the drawing) for each switch section 10 is rotated by the rotary shaft 12 for sequentially making or breaking circuits between the rotor contacts and the contacts spaced angularly around the stator 16. However, the current capacity of the switch is limited by the size of the rotor and stator contacts. And in many situations, space requirements limit the overall size of the rotary switch and in turn limit the size of the contacts.

The device of this invention, for providing high current switching, comprises a cam 20 which Works against a carneengaging portion 21 of a leaf spring 22 which carries a contact 24 at one end thereof. The leaf spring 22 normally urges contact 24 into engagement with a fixed contact member 26. Fixed contact 26 is conductively connected through a bracket 28 to a terminal lug 30. The opposite end of the leaf spring 22 is conductively connected through a bracket 32 to a second terminal lug 34. The brackets 28, 32 and terminal lugs 30, 34 are secured to stator 16 by rivets 36. Obviously, the leaf spring 22 and terminal lugs 34 may be mounted on other portions of the switch frame in any appropriate manner. Leaf spring 22 and fixed contact 26 may be so positioned that the contacts are normally open with cam 20 intermittently closing the contacts.

Cam plate 20 pivots about strut spacer 18 and is sandwiched between a pair of bearing plates 38 which are positioned on the strut screws by spacers 18. The cam plate 20 has an aperture 20a through which rotary shaft 12 extends.The cam plate is actuated by the rotary shaft which, in the embodiment shown in the drawing, is Square in the working area within aperture 20a. To prevent excessive wear of the cam, a roller 42 is loosely set within a recess 44 positioned in the periphery of aperture 20a in radial alignment with the cam-engaging portion 21 of leaf spring 22. Obviously, the roller may be omitted and the periphery of aperture 20a formed with an integral pro` jection to ride on the surface of the square on shaft 12.

In operation, rotation of the rotary shaft 12 causes one of the high points of the square portion of the shaft to come into contact with roller `42. The high point of the square pushes the roller and the cam generally radially outward in an arc about strut screw 14a in the direction of arrow A (FIG. 2) against leaf spring 22 at point B. Opening 20a in cam plate 20 is sufficiently large to permit the cam to move in the direction of arrow A without having the lefthand margin (as seen in FIG. 2) of the aperture engage shaft 12. When a high point of the square has reached its maximum in relation to its engagement with roller 42, contact 24 carried by leaf spring 22 is moved a sufficient distance away from fixed contact member 26 to break the electrical current flowing through them. This position of the cam plate 20, roller 42 and leaf spring 22, when a high point of the square has reached its maximum, is shown by dot-dash lines in FIG. 2.

As is known, the rotary shaft 12 is rotated in increments corresponding to the shaft detent positions established by detent mechanisms for the rotary switch. The orientation of the square on the shaft (for moving cam plate 20) may be such as to allow switching in increments different from but in multiples of the detent increments for the rotary shaft. The high points of the square on the shaft are rounded slightly so that roller 42 rests thereon and maintains contacts 24 and 26 spaced from each other when the shaft is in a detented position. Further rotation of the shaft allows the roller and cam to come back to a position as shown in FIG. 2 with the contacts 24 and 26 again closed. Since the shaft illustrated herein is square,7 four high points are presented for each revolution of the shaft and thus four contact openings and closings. Obviously, variations of this cycle can be accomplished by changing the configuration of the portion of the shaft within opening 20a of cam plate 20 to provide rises and falls for engaging roller `42 to move cam 20. For instance, a double D configuration of the shaft will give two contact openings per revolution with a long off time.

Thus it can be seen that by providing the contact carrying leaf spring 22, which is of a greater size than the contacts normally used with each switch section 10, the same rotary shaft is utilized to allow switching of a higher current than is attainable with the contacts of the switch sections. In addition, this heavy-duty switching is permitted in increments the same as or in multiples of the shaft detent increments.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modications will be obvious to those skilled in the art.

I claim:

1. In a rotary switch, a frame, a shaft rotatably mounted on said frame for operating switch section for the rotary switch, a fixed contact member mounted on said frame radially outwardly from said shaft, a contact carrying leaf spring spaced radially from said shaft with the contact carried by the leaf spring in position for engaging and disengaging the xed contact member, an actuating cam member pivotally mounted on said frame at a point spaced radially from said shaft and spaced from said contact carrying leaf spring angularly about said shaft, means dening an aperture in said cam member, and means on said shaft for intermittently engaging a portion of the periphery of 'said aperture to pivot said cam member against said leaf spring in response to rotation of the shaft to move the contact on said leaf spring with respect to said fixed contact.

2. The rotary switch of claim 1 wherein said shaft has a rectangular cross sectional configuration within said aperture with the high points of said rectangular configuration comprising said means for engaging said cam member to move the leaf spring contact with respect to the fixed contact four times for each revolution of said rotary shaft.

3. The rotary switch of claim 1 including a roller loosely positioned in a recess in the periphery of said aperture in radial alignment with said leaf spring and projecting from the periphery of said aperture for engaging said shaft to move said cam member against said leaf spring.

4. The rotary switch of claim 1 wherein said shaft has a plurality of rises and falls about the periphery of the shaft for intermittently engaging a portion of the periphery of said aperture to move said cam member against said leaf spring in response to rotation of said shaft to move the contact of said leaf spring with respect to said fixed contact.

5. The rotary switch of claim 4 including a roller set loosely within a recess in the periphery of said aperture in radial alignment with said leaf spring and projecting from the periphery of said aperture for engaging the rises and falls on said shaft to move said cam member against said leaf spring.

6. The rotary switch of claim 5 wherein said roller is radially aligned with a mid point of said leaf spring.

7. In a rotary switch, a frame including two diametric strut screws, a switch section including a stator mounted on said diametric strut screws and a rotor, a shaft rotatably mounted on said frame for operating the rotor of said switch section, a fixed contact member mounted on said frame radially outwardly from said shaft, a contact carrying leaf spring spaced radially from said shaft and parallel with a diameter intersecting said strut screws with the contact carried by the leaf spring in position for engaging and disengaging the xed contact member, an actuating cam member pivoted on one of said strut screws for intermittent movement against said leaf spring in response to rotation of said shaft to move the contact of said leaf spring with respect to said fixed contact, and bearing plates on opposite sides of said cam member for positioning said cam member in alignment with said leaf spring.

References Cited UNITED STATES PATENTS 1,766,908 6/1930 Kindl 20G-22 2,225,344 12/ 1940 Kimball 200-6 2,626,334 1/1953 Koenig 200`6 2,939,337 6/ 1960 Sweger 200-6 3,260,803 7/ 1966 Moroishi 200-6 ROBERT K. SCHAEFER, Primary Examiner ROBERT A. VANDERHYE, Assistant Examiner U.S. Cl. X.R.

ZOU-21, 30, 153

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