US3668345A

US3668345A - Electric switch with improved cam operated pivoted contact

Info

Publication number: US3668345A
Application number: US79032A
Authority: US
Inventors: Oka Tsumoru
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1969-10-14
Filing date: 1970-10-08
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

A switch particularly adapted for use with a variable resistance mechanism comprises a first fixed contact having an arcuate contact edge, a second generally U-shaped fixed contact spaced from said first fixed contact, and a resilient movable contact, one end of which is secured to one leg of the second fixed contact, said movable contact being normally flexed with its other free end biased into engagement with the arcuate edge of said first fixed contact. A rotor is provided with an integrally formed projection having a recess adapted to engage the free end of said movable contact in confining relationship. Electrical connection between the first and second fixed contacts through the movable contact is broken as the rotor is rotated in one direction engaging the free end of the movable contact in the recess formed in said projection. The rotation of the rotor in the opposite direction allows the movable contact to resile into operative electrical engagement with said first fixed contact. This is accomplished by means of a stop member on the other leg of said second fixed contact adapted to engage the free end of said movable contact.

Description

United States Patent Tsumoru [21] Appl. No.: 79,032

[30] Foreign Application Priority Data Oct. 14, 1969 Japan ..44/98006 [52] 11.8. CI ..200/6 BB, 200/ l 1 R, 200/166 8H [51] Int. Cl ..H0lh 1/06, HOlh 1/34 [58] Field of Search ..200/5 R, 11 R, 6 BB, 16 R,

200/166 Bl-l; 338/200 [5 6] References Cited UNITED STATES PATENTS 3,324,261 6/1967 Burns ..200/166 BH X- 2,939,337 6/1960 Sweger... ZOO/6 BB X 2,942,221 6/1960 Girolamo ..338/200 2,870,273 1/1959 Merchant ...200/l6 R X 3,221,115 11/1965 Feher ..200/16 R [451 June 6,1972

3,497,643 2/1970 Heath ..200/6 BB Primary Examiner.l. R. Scott Attorneylames and Franklin [57] ABSTRACT A switch particularly adapted for use with a variable resistance mechanism comprises a first fixed contact having an arcuate contact edge, a second generally U-shaped fixed contact spaced from said first fixed contact, and a resilient movable contact, one end of which is secured to one leg of the second fixed contact, said movable contact being normally flexed with its other free end biased into engagement with the arcuate edge of said first fixed contact. A rotor is provided with an integrally formed projection having a recess adapted to engage the free end of said movable contact in confining relationship. Electrical connection between the first and second fixed contacts through the movable contact is broken as the rotor is rotated in onedirection engaging the free end of the movable contact in the recess formed in said projection. The rotation of the rotor in the opposite direction allows the movable contact to resile into operative electrical engagement with said first fixed contact. This is accomplished by means of a stop member on the other leg of said second fixed contact adapted to engage the free end of said movable contact.

21 Claims, 8 Drawing Figures PATENTEnJun 6 I972 SHEET 10F 2 FIG. 2A

i Jr my n B 2 INVENTOR rsu/va/au 0K4 ATTORNEY PATENTEDJun 6 m2 SHEET 2 OF 2 /2 Ya 7a FIG. 3 21 x INVENTOR TSuMOIEU OKA ATTORNEY ELECTRIC SWITCH WITH IMPROVED CAM OPERATED PIVOTED CONTACT This invention relates to an electrical contact switch and more particularly to a switch adapted for use with a variable resistor or rheostat mechanism.

Electrical switches of the type herein described are designed to make and break electrical contact between two fixed contact members in response to the rotation'of a rotor. The same rotor is adapted to control the resistance of a rheostat or potentiometer mechanism which may be connected in the same circuit.

In prior art electrical switches of this type, it has been necessary to provide a switch of considerable size with a large switching angle to effect the necessary switching operation. The use of such large switching angles considerably limits the angle of rotation of the rotor which is effective to vary the resistance of the rheostat mechanism. In addition electrical contact switches of this type are susceptible to deposits of dirt and grime and oxidation of the operative contact surfaces, thereby interfering with the establishment of good electrical contact. Finally, over a period of time wear or deformation of the operative contact elements may have a deleterious effect on the making and breaking of the electrical contact. Accordingly it is a primary object of the present invention to provide a miniature electrical contact switch adapted for use with a rheostat or the like in which the operative switching angle is relatively small.

It is a further object of the present invention to provide an electrical contact switch in which the operative contact elements are adapted to provide a self-cleaning operation on the contact surfaces during operation.

It is yet another object of the present invention to design an electrical contact switch in which the on and off conditions are positively effected and maintained notwithstanding considerable wear and/or pennanent deformation of the operative contact elements.

To these ends the present invention resides in a switch comprising a rotor formed with a projection having a recess therein, two fixed contacts, and an elongated resilient movable contact secured at one end to one of said fixed contacts, its other end being free and normally biased into operative electrical engagement with the other fixed contact by virtue of its resiliency. Rotation of the rotor in a first direction is effective to break electrical contact between the free end of the resilient member and the other fixed contact, the recess in said projection moving into confining engagement with said free end of said movable contact. Means are provided for releasing the free end of the movable contact from its engagement with the recess on said projection as the rotor is rotated in the opposite direction.

To the accomplishment of the above, and to such other objects as may hereinafter appear, thepresent invention relates to an electrical contact switch as defined in the appended claims and as described herein with reference to the accompanying drawings in which:

FIG. I is an exploded perspective view of a switch in accordance with the present invention in association with a variable resistor mechanism;

FIG. 2A is a front elevational view of the assembled switch and variable resistor of FIG. 1;

FIG. 2B is a side elevational and variable resistor of FIG. 1;

FIGS. 3A through 30 are schematic illustrations showing in successive steps the operation of the switch in breaking electrical contact;

FIG. 3D is a schematic illustration showing the method of re-establishing electrical contact; and

FIG. 4 is a schematic illustration of the two fixed contacts showing possible modifications in the shape thereof.

Referring now to the drawingsand specifically to FIGS. 1 and 2A the switching mechanism of the present invention comprises a flat circular switch base 2 of insulating material adapted to mount the operative switching elements. For this view of the assembled switch purpose it is provided with two narrow slots 4 and 5 and is notched at 6 at four evenly spaced points along its periphery.

through corresponding slot 4 in switch base 2 and to be electrically connected to appropriate leads in the circuit. A second fixed contact 16 comprises a generally U-shaped contact member 18 having two

leg portions

20 and 22 respectively extending horizontally in parallel relationship. The smaller leg 20 is provided at its inner edge near its free end with a groove or cut out portion 24 adapted to receive one end of a resilient contact as will hereinafter be described. Fixed contact 16 is likewise provided with a vertically extending terminal 26 adapted to be inserted through corresponding slot 5 in switch base 2 and to be electrically connected to appropriate leads in the circuit.

The resilient contact is generally designated 28 and comprises a strip of resilient metal provided with a slot 30 at one end thereof adapted to engage the cut out portion 24 in leg 20 of fixed contact 16. The other end 32 of movable contact 28 is bent over in a generally U-shaped configuration and constitutes the free movable contact surface thereof. Resilient contact 28 is shown in FIG. 1 in its unstressed or unflexed position in which it will be noted that its

ends

30 and 32 are cally in FIG. 3A movable contact 28 is fixedly secured to fixed contact 16 by the mating of slot 30 and cut out portion 24. For proper electrical contact it may be necessary to apply solder at this connection. Referring again to FIG. 1 a cylindrical metallic cover member generally designated 34 is adapted to house the movable contact 28 and the two

fixed contacts

8 and 16 in the proper operative relationship. For this purpose member 34 is provided with four vertically extending tabs 36 equally spaced along the periphery of its upper surface and adapted to register with peripheral notches 6 on switch base 2. Accordingly, the switch is assembled by securing movable contact 28 to fixed contact 16 as previously described and inserting terminals 14 and 26 through slots 4 and 5, respectively, of switch base 2. Cover member 34 is then inserted over the entire assembly with tabs 36 extending through notches 6. As best shown in FIG. 2A the tabs 36 are bent over onto the base member 2 to secure the switch assembly in place.

Referring again to FIG. 3A it will be seen that in the assembled configuration the resiliency of movable contact 28 is effective to urge its free end 32 forcefully into engagement with the arcuate contact surface 12 of the other fixed contact 8. This constitutes the closed position of the switch.

The foregoing switch assembly is adapted for use with a rotatably adjustable variable resistor or rheostat mechanism. One such mechanism generally designated 38 is illustrated in exploded perspective in the poses, the switch assembly being adapted for use with a variety of mechanisms of this general type. As shown the rheostat assembly comprises a rotor body generally designated 40, a resist'or body generally designated 42 and a control shaft 44.

Resistor body 42 comprises a base 46 having a central aperture 48 and a hollow tubular member 50 extending downwardly therefrom and cooperating with aperture 48 to define a passage through which control shaft 44 extends. Disposed on the upper surface of base 46 is a generally U shaped resistor 52 defining an outer track and an inner conductive track 53 spaced from resistor track 52. The body 42 is provided with three vertically extending terminals 54, 56 and 58, respectively. The outer terminals 54 and 58 are electrically connected to the two legs respectively of the resistor track 52 and the middle terminal 56 is electrically connected to the conductive track 53 in any suitable manner.

I Control shaft 44 is provided with a portion 60 of reduced cross section which carries a nutlike portion 62 at its terminal nutlike body 62 on control shaft 44. Nutlike body 62 is adapted to extend through corresponding aperture 68 thus placing rotor 40 in driving relationship with control shaft 44. Rotor 40 is provided with two brushes 70 and 72 extending therefrom and adapted to ride on resistive track 52 and conductive track 53 respectively as the rotor is driven by means of control shaft 44. In practice terminals 54 and 58 are connected across a voltage source. Terminal 56 constitutes the pick-off terminal and its potential will vary between that of terminals 54 and 58 depending upon the position of brush 70 on resistive track 52 which in turn will depend upon the rotative position of control shaft 44.

Rotor body 66 is provided at its upper surface with an integrally formed vertically extending projection 74 having a generally V-shaped recess 76 adapted to engage the free end 32 of resilient contact 28. As best illustrated in FIG. 3A the rheostat mechanism 38 is assembled inoperative position adjacent the switch assembly with projection 74 extending into the plane of rotation of movable contact 28. Cover member 34 is provided with a second set of four equally spaced tabs 78 extending from its lower surface and adapted to engage four corresponding notches 80 in the periphery of resistor base 46 in the same manner previously described with respect to tabs 36.

The operation of the device will now be explained with reference to FIGS. 3A through 3D. As previously mentioned FIG. 3A schematically illustrates the closed or on position of the movable contact 28 with its free end 32 resiliently pressed against contact surface 12 of fixed contact 8. Projection 74 of rotor 40 is shown spaced from movable contact 28 somewhat to the right thereof. Referring now to FIG. 38, as the rotor is rotated counterclockwise (in the direction of arrow 82) by means of control shaft 44 projection 74 engages free end 32 of movable contact 28 causing the elastic deformation shown in FIG. 3B. Continued counterclockwise rotation of projection 74 will force free end 32 of contact 28 into recess 76 as shown in FIG. 3C. In this position the switch is open, the free end 32 of contact 28 being substantially spaced from contact surface 12 of fixed contact 8 by virtue of its snug engagement within the recess 76 of projection 74. Referring now to FIG. 3D, as rotor 40 and thus projection 74 is rotated clockwise (in the direction of arrow 84) by means of control shaft 44 the free end 32 of movable contact 28 remains confined in recess 76 and travels therewith remaining out of engagement with fixed contact 8 until it reaches the position shown in FIG. 3D. At this point it will be noted that end'32 of contact 28 engages the inclined surface 88 of leg 22 of U- shaped contact 18 and thus further movement of projection 74 will result in the disengagement of free end 32 from recess 76. As a result contact 28 will resile or snap back into the posi tion shown in FIG. 3A to again close the circuit.

In operation tenninals 14 and 26 will normally be connected in the same circuit as terminal 56 on resistor body 42.

- Thus it will be possible by turning a single control shaft to switch on power in the circuit and adjust the desired potential. The range of resistance variation and thus the range of voltages to which terminal 56 may be subjected will depend upon that portion of the turning radius of control shaft 44 which is taken up in the switching action. Thus in order to increase the resistance range it is necessary to decrease the switching angle required to move resilient contact 28 from the position shown in FIG. SC to that position in FIG. 3D.

As best illustrated in FIG. 4 the switching angle may be considerably reduced by modifying the configuration of the contact surface 12 of fixed contact 8 and/or the configuration of the leg 22 of fixed contact 16 defining the stop member. Two such modifications of contact surface 12 are there shown in dotted lines and dot-dash lines, respectively. In this manner the initial off position of projection 74 (FIG. 3C) will be moved somewhat to the right. In addition, leg 22 may be moved to the left to shorten the counterclockwise stroke of movable contact 28 when engaged in recess 76.

It will be apparent from the foregoing that I have provided a switch which is relatively simple in construction and operation and is adapted to make and break a circuit under the control of the rotor of a variable resistance mechanism.

A relatively small switching angle is provided by an appropriate design of the shape of the fixed contacts. Moreover, since the movable contact slides with considerable pressure on the contact surface 12 of fixed contact 8 during switching, there is a self-cleaning effect associated therewith to maintain the contact surfaces free of dirt, grime or other foreign matter.

Finally because contact surface 12 is curved, wear of the contact members and/or permanent deformation of resilient contact 28 will not adversely affect the making or breaking of electrical contact but rather will merely result in the free end 32 of resilient contact 28 engaging a different portion of contact surface 12.

While only one preferred embodiment of the present invention has been specifically described herein, it will be appreciated that many variations may be made therein, all within the scope of the present invention as defined in the following claims.

I claim:

1. An electrical contact switch comprising a frame, a contact fixedly mounted on said frame, a movable contact mounted onsaid frame so as to be normally biased in a given direction against the fixed contact to operatively electrically connect said contacts, and a movable member mounted on said frame movable in a first direction having a substantial component of movement transverse to said given direction and in a second direction and effective on movement thereof in said first direction to holdingly engage said movable contact and carry it generally in said first direction and out of operative engagement with said fixedcontact, and means to release said movable contact from said movable member upon move ment of said movable member in said second direction, thereby allowing said movable contact toreturn to its normally biased position in engagement with said fixed contact.

2. The switch of claim 1, wherein said movable member is provided with a recess adapted to holdingly receive an end of said movable contact thereby to move said received end of said movable contact out of engagement with said fixed contact on movement of said movable member in said first direction.

3. The switch of claim 1, wherein said fixed contact is provided with a curved contact surface. I

4. The switch of claim 2, wherein said fixed contact is provided with a curved contact surface.

5. The switch of claim 2, wherein said movable contact is resilient and is normally biased by its resilience against said fixed contact and wherein said release means is effective to release said received end of said movable contact from its engagement with said recess, thereby to allow said received end of said movable contact to resile into engagement with said fixed contact.

6. The switch of claim 2, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said other end of said movable contact, thereby to disengage said other end of said movable contact from said recess as said movable member moves in said second direction past said stop means.

7. The switch of claim 1, wherein said movable member is operatively connected to the rotor of a variable resistance mechanism.

8. The switch of claim 1, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said movable contact as the latter is holdingly carried by said movable member as the latter moves in said second direction and then disengage said movable contact from said movable member as said movable member moves past said stop means.

9. An electrical contact switch comprising a frame, first and second contacts fixedly mounted on said frame, a movable contact secured at one end to one of said fixed contacts, its other end being normally biased in a given direction against the other of said fixed contacts to operatively electrically connect said fixed contacts, and a movable member mounted on said frame movable therein in a first direction and in a second direction and effective on movement thereof in said first direction to holdingly engage said other end of said movable contact and carry it generally in said first direction and out of operative engagement with said other fixed contact, and means to release said movable contact from said movable member upon movement of said movable member in said second direction thereby allowing said movable contact to return to its normally biased position, said releasing means comprising stop means on said one fixed contact effective to engage said other end of said movable contact thereby to disengage said other end of said movable contact from said recess as said movable member moves in said second direction past said stop means.

10. The switch of claim 9, wherein said other fixed contact is provided with a curved contact surface.

11. The switch of claim 9, wherein said other fixed contact is provided with a curved contact surface.

12. The switch of-claim 9, wherein said movable contact is resilient and is normally biased by its resilience against said other fixed contact and wherein said release means is effective to release said other end of said movable contact from its engagement with said recess, thereby to allow said other end of said movable contact to resile into engagement with said other fixed contact.

13. The switch of claim 9, wherein said operatively connected to the rotor mechanism.

14. An electrical contact switch comprising a frame, a contact fixedly mounted on said frame and having an engageable contact surface, a movable contact mounted on said frame so as to be normally biased in a given direction against said engageable surface of said fixed contact to operatively electrically connect said contacts, and a movable member mounted on said frame and movable in a first direction and in a second direction and effective on movement thereof in said first direction to holdingly engage said movable contact and carry it generally in said first direction and also impart a degree of movement thereto in a direction different from said first direction generally opposite to said given direction, thereby to move said movable contact out of operative engagement with said fixed contact, and means to release said movable contact from said movable member upon movement of said movable member in said second direction, thereby allowing said movable contact to return to its normally biased position in engagement with said fixed contact.

15. The switch of claim 14, wherein said movable member is provided with a recess adapted to holdingly receive an end of said movable contact thereby to move said received end of movable member is of a variable resistance said second direction past 17. The switch of claim 14, wherein said releasing means mounted on said frame adjacent the said movable member in said second direction and effective to engage said movable contact as the latter is holdingly carried lay said movable member as the latter moves in said second irection and then disengage said movable contact from said movable member as said movable member moves past said stop means.

18. An electrical contact switch comprising a frame, a conit generally in said first direction and out of operative engagement with said fixed contact against said bias, and effective upon a first increment of movement thereof in said second direction to holdingly engage said movable contact and carry it generally in said second direction away from said fixed contact against said bias, and means to release said movable contact from said movable member upon a second increment of movable member in said second direction, subsequent to said first increment thereof, thereby allowing said movable contact to return to its normally biased position in engagement with said fixed contact.

19. The switch of claim 18, wherein said movable member is provided with a recess adapted to holdingly receive an end of said movable contact thereby to move said received end of said movable contact out of engagement with said fixed contact on movement of said movable member in said first direction.

20. The switch of claim 19, wherein said releasing means comprises stop means mounted on said frame adjacent the direction and effective to engage said other end of said movable contact, thereby to disengage said other end of said movable contact from said recess as said movable member moves in said second direction past said stop means.

21. The switch of claim 18, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said movable contact as the latter is holdingly carried by said movable member as the latter moves in said second direction and then disengage said movable contact from said movable member as said movable member moves past said stop means.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent; No. 3,668,345 Dated June 6, 1972 Inven tofls) Tsumoru Oka It is certified that error appears iri the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [72] the inventor's name "Oka Tsumoru" should read Tsumoru Oka,

Signed and sealed this 7th day of November 1972.

(SEAL) Attest:

EDWARD M .FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents ORM PO-1050 (10-69) uscoMM-Dc 60376-P69 U.S GOVERNMENT PRINTING OFFICE: I969 0-366-334,

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,668,345 I I D te June 6, 1212 lnvenfofls) Tsumoru Oka It is certified that error'appeai's in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [72] the inventor's name "Oka Tsumoru" should read Tsumoru Oka Signed and sealed this 7th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting' Officer ROBERT GGTTSCHALK Commissioner of Patents FORM 304050 (10-69) USCOMM-DC 603764 69 a U.S. GOVERNMENT PRNYING OFFICE I 969 036B"334.

Claims

1. An electrical contact switch comprising a frame, a contact fixedly mounted on said frame, a movablE contact mounted on said frame so as to be normally biased in a given direction against the fixed contact to operatively electrically connect said contacts, and a movable member mounted on said frame movable in a first direction having a substantial component of movement transverse to said given direction and in a second direction and effective on movement thereof in said first direction to holdingly engage said movable contact and carry it generally in said first direction and out of operative engagement with said fixed contact, and means to release said movable contact from said movable member upon movement of said movable member in said second direction, thereby allowing said movable contact to return to its normally biased position in engagement with said fixed contact.

3. The switch of claim 1, wherein said fixed contact is provided with a curved contact surface.

12. The switch of claim 9, wherein said mOvable contact is resilient and is normally biased by its resilience against said other fixed contact and wherein said release means is effective to release said other end of said movable contact from its engagement with said recess, thereby to allow said other end of said movable contact to resile into engagement with said other fixed contact.

13. The switch of claim 9, wherein said movable member is operatively connected to the rotor of a variable resistance mechanism.

15. The switch of claim 14, wherein said movable member is provided with a recess adapted to holdingly receive an end of said movable contact thereby to move said received end of said movable contact out of engagement with said fixed contact on movement of said movable member in said first direction.

16. The switch of claim 15, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said other end of said movable contact, thereby to disengage said other end of said movable contact from said recess as said movable member moves in said second direction past said stop means.

17. The switch of claim 14, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said movable contact as the latter is holdingly carried by said movable member as the latter moves in said second direction and then disengage said movable contact from said movable member as said movable member moves past said stop means.

18. An electrical contact switch comprising a frame, a contact fixedly mounted on said frame, a movable contact mounted on said frame so as to be normally biased in a given direction against said fixed contact to operatively electrically connect said contacts, and a movable member mounted on said frame and movable in a first direction and in a second direction and effective on movement thereof in said first direction to holdingly engage said movable contact and carry it generally in said first direction and out of operative engagement with said fixed contact against said bias, and effective upon a first increment of movement thereof in said second direction to holdingly engage said movable contact and carry it generally in said second direction away from said fixed contact against said bias, and means to release said movable contact from said movable member upon a second increment of movement of said movable member in said second direction, subsequent to said first increment thereof, thereby allowing said movable contact to return to its normally biased position in engagement with said fixed contact.

20. The switch of claim 19, wherein said releasing means comprises stop means mounted on said frame adjacent the path of movement of said movable member in said second direction and effective to engage said other end of said movable contact, thereby to disengage said other end of said movable contact from said recess as said movable member moves in said second direction past said stop means.