US3617973A - Electric switch - Google Patents

Abstract

An electric switch in which a pair of blades having contacts thereon are mounted on a base. A bimetallic blade is also mounted on said base in engagement with one of said pair of blades to vary the position of their contacts with respect to each other in response to temperature changes. A sleeve adjustably carried in a rigid arm mounted on the base has a pin projecting therefrom for engagement with one of said pair of blades to vary the position of their contacts with respect to each other for controlling the temperature at which said bimetallic blade will effect contact opening and closing. Said pin is also movable with respect to the sleeve by a cam swingably mounted in said sleeve to vary the position of the contacts between an off position in which they are prevented from closing and an on position in which they are opened and closed under the action of the bimetallic blade.

Description

United States Patent Inventor Amos E. Chesnut 1 Columbus, Ind. Appl. No. 47,750 Filed June 19, 1970 Patented Nov. 2, 1971 Assignee Arvin Industries, Inc.

Columbus, Ind.

ELECTRIC SWITCH 6 Claims, 4 Drawing Figs.

US. Cl. 337/375, 337/349, 337/361 Int. Cl H0lh 37/18 Field of Search 337/67, 342, 349, 347, 360, 361, 368, 374, 375; 200/170; 219/515 References Cited UNITED STATES PATENTS 2,741,682 4/1956 Schwaneke et a1. 337/375 Wily/11 Primary Examiner-Bernard A. Gilheany Assistant ExaminerF. E. Bell Attorney-Trask, Jenkins and Hanley ABSTRACT: An electric switch in which a pair of blades having contacts thereon are mounted on a base. A bimetallic blade is also mounted on said base in engagement with one of said pair of blades to vary the position of their contacts with respect to each other in response to temperature changes. A sleeve adjustably carried in a rigid arm mounted on the base has a pin projecting therefrom for engagement with one of said pair of blades to vary the position of their contacts with respect to each other for controlling the temperature at which said bimetallic blade will effect contact opening and closing. Said pin is also movable with respect to the sleeve by a cam swingably mounted in said sleeve to vary the position of the contacts between an off position in which they are prevented from closing and an on position in which they are opened and closed under the action ofthe bimetallic blade.

PATENTEDHM ml 3.617.973

118-3 AMOS E. CH

ELECTRIC SWITCH BACKGROUND OF THE INVENTION Thermostatically controlled electric switches for portable heaters and the like are well known in the art and in wide com mercial use. One such switch is shown in my prior US. Pat. No. 3,27l,546. In such switches there is provided a pair of contact blades, one of which is engaged and moved by a bimetallic blade to open and close the contacts on the blades in response to temperature changes. In order to control the temperature at which the bimetallic blade will effect contact opening or closing an adjustable insulating pin is disposed in engagement with one of the contact blades to vary the spacing between the contacts.

Positive on-off conditions for such switches are provided by two different types of structures. In one such structure, a separate on-off switch is electrically connected to the thermostatic switch. This is a relatively expensive structure, however, since it requires a separate switch with its attendant expense in manufacture, mounting and wiring. In the other structure conventionally used, the insulating pin is moved by the temperature control member to move the blades into extreme relative positions such that the bimetallic blade is rendered ineffective to cause contact closing or opening. This means that the switch can not be moved to its on or off position without changing the thermostat setting.

It is an object of this invention to provide an improved electric switch which will overcome these disadvantages by the provision of an electric switch which will have a thermostatic control capability but which will also provide an on-off control without the necessity of providing any additional separate switch means or require a change in the thermostat setting.

SUMMARY OF THE INVENTION In accordance with one form of the invention, first and second blades provided with first and second contacts are mounted on an insulating base. A bimetallic blade is also mounted on said base and is engageable with said first blade to vary the position of the contacts with respect to each other in response to temperature changes.

A rigid arm is mounted on the base and supports an adjustable sleeve provided with an insulating pin engageable with said second blade to adjust the relative positioning of the contacts and provide calibrated adjustment of the temperature of actuation of the contacts by the bimetallic blade. A cam is adjustably mounted on said sleeve in engagement with said pin. Said cam is adapted to move the pin relative to the sleeve between an off position in which it causes said pin to move the second blade into a position in which the contacts cannot close and an on position in which said pin disposes said second blade in a position in which said bimetallic blade can effect contact closing and opening in response to temperature change.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a side elevation of an electric switch embodying the invention;

FIG. 2 is a fragmentary horizontal section taken on the line 2--2 of FIG. 1;

FIG. 3 is a fragmentary vertical section taken on the line 3-- 3 of FIG. 2; and

FIG. 4 is a front elevation of the control knob shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings, the switch comprises a base formed from a plurality of insulating blocks 12 held in a stacked position by a bolt 14. First and second resilient contact blades 15 and 16 have one of their ends mounted on the base 10 and separated by one of the blocks 12 to electrically insulate them from each other. Desirably, terminals 17 and 18 are mounted on the blades for connecting them to appropriate electrical leads. The blades project outwardly from the base and contacts 20 and 21 are mounted on blades 15 and 16, respectively, adjacent their ends remote from said base. The blades, due to their inherent resiliency, are urged toward each other toward a contact closing position. A bimetallic blade 22, electrically insulated from blade 16 by one of the blocks 12, is also mounted on the base 10. The outer end of blade 22 is bent to engage blade 15 for thus causing the contacts 20 and 21 to be moved into and out of engagement with each other in response to temperature changes.

A rigid arm 24 is mounted on the base 10 in an insulated position from blade 15 by one of the blocks 12. Conveniently, said arm may be provided with wings 26 for mounting it in a heater or other structure. A threaded boss 28 is mounted on the arm for the reception of an adjusting sleeve 30. As shown, an insulating pin 32 is slidably mounted in sleeve 30 and projects outwardly from the inner end thereof through an opening 33 in blade 15 and into engagement with blade 16. Conveniently, the blade 16 may be dented, as at 35, for locating the pin 32 against said blade.

As best shown in FIGS. 2 and 3, the outer end of the sleeve 30 is bifurcated to form a longitudinally extending slot 38 extending inwardly from the outer end of said sleeve. A cam 40 is swingably mounted in the slot 38 by a pin 42 and comprises a cam nose 43 and an arm 44 projecting outwardly from the outer bifurcated end of the sleeve. The pin 32 is held in operative engagement with the cam nose 43 by the inherent resilien' cy of the blade 16. In this manner, the pin 32 is moved toward and away from the blade 16 during rotational adjustment of the sleeve for varying the spacing between the contacts 20 and 21. It is also movable with respect to said sleeve by the cam to move the blade 16 into an off position in which the contacts 20 and 21 can not close and into an on position in which said contacts can open and close in response to movement of the bimetallic blade 22.

A control knob 45 is mounted on the bifurcated end of the sleeve to facilitate the rotational adjustment of said sleeve. As shown, said knob comprises an inner collar 46 received around the sleeve end and interconnected by an annular web 47 to an outer collar 48. A face plate 49 is seated within the collar 48 and extends over the web 47. The cam arm 44 projects outwardly through the collar 46 and is slidably guided in an elongated slot 50 formed in the face plate 49.

The control knob may be rotated in front of suitable indicia on the device upon which the switch in mounted to thus provide calibrated adjustment of the temperature of actuation of the contacts 20 and 21 by the bimetallic blade 22. Conveniently, a finger 52 is struck outwardly from the arm 24 in the path of rotation of a lug 54 mounted on the sleeve 30 to limit rotational movement of said sleeve and thus limit the positioning of contact 21 with respect to contact 20 upon rotation of said sleeve. The finger 52 also carries a loop spring 53 bindingly embracing the sleeve 30 for frictionally retarding rotation of said sleeve and thereby serving to hold the sleeve in the desired position of adjustment.

In the operation of the switch, the cam arm 44 is moved into its downward position as shown in FIG. 3 thereby permitting the pin 32 to slide in the sleeve 30 under the biasing of blade 16 into an on position in which the contacts 20 and 21 are spaced from each other by a distance which will permit them to open and close upon movement of the bimetallic blade 22 in response to temperature changes. The temperature at which the contacts will open and close in response to movement of the bimetallic blade 22 is controlled by rotation of the sleeve 30 to cause the pin 32 to move the blade 16 into the desired spacing with respect to the blade 15. When it is desired to open the switch so that it will not close irrespective of the movements of the blade 22, the cam arm 44 is moved upwardly as viewed in FIG. 3 to cause the cam nose 43 to slide pin 32 inwardly with respect to the sleeve 30 and move the blade 16 into an off position such that its contact 21 will be spaced from contact 20 to prevent the closing of said contacts.

It is to be understood, of course, that if desired, the switch may also have employed with it a tip-over pendulum assembly such as is shown in my aforementioned US. Pat. No. 3,271,546.

I claim:

1. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and projecting outwardly from one end thereof for engagement with one of said and second blades to vary theposition of the contacts with each other upon adjustment of said sleeve, and a cam mounted on said sleeve and engageable with said pin to move said pin to cause it to move one of said first and second blades to vary the position of the contacts with respect to each other irrespective of the adjusting movements of the sleeve.

2. The invention as set forth in claim 1 with the addition that said sleeve has a control knob mounted on its end opposite said pin and said cam projects outwardly from said sleeve through said knob.

3. The invention as set forth in claim 1 in which said first and second blades are spring-biased toward each other, and the spring tension on the blade engageable with the pin holds said pin in engagement with said cam.

4. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and projecting outwardly from one end thereof for engagement with one of said first and second blades to vary the position of the contacts with each other upon adjustment of said sleeve, the end of the sleeve opposite its said one end being bifurcated, a control knob mounted on the bifurcated sleeve end, and a cam swingably mounted in said bifurcated sleeve end having a cam nose engageable with said pin and an arm projecting outwardly through said control knob, said cam being swingable to move said pin to cause it to move one of said first and and second blades to vary the position of the contacts with respect to each other irrespective of the adjusting movements of the sleeve.

5. The invention as set forth in claim 4 in which said control knob has an elongated slot formed therein, and said cam arm is slidably carried in said slot.

6. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and movable with and with respect to said sleeve, said pin being engageable with one of said first and second blades to vary the position of said contacts with respect to each other upon movement of said pin with and with respect to said sleeve, and means projecting outwardly from said sleeve and engaging said pin for sliding pin outwardly with respect to said sleeve toward said first or second blade engaging said pin, said first or second blade said pin urging said pin into engagement with said means whereby said pin is releasably retained in position with respect to said sleeve by said means and said first or second blade engaging said pin.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,617,973 Dated November 2. 1971 Inventofls) Amos E. Chestnut (Assignee Arvin Industr1es,Inc.)

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 50 "in" should be --is-- Column 3, claim 1, line 16, after "said" insert --first-- Column 4, claim 6, line 29 after "sliding" insert --said-- Column 2, line 74 "upwardly" should be "downwardly".

Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims (6)

1. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and projecting outwardly from one end thereof for engagement with one of said and second blades to vary the position of the contacts with each other upon adjustment of said sleeve, and a cam mounted on said sleeve and engageable with said pin to move said pin to cause it to move one of said first and second blades to vary the position of the contacts with respect to each other irrespective of the adjusting movements of the sleeve.

2. The invention as set forth in claim 1 with the addition that said sleeve has a control knob mounted on its end opposite said pin and said cam projects outwardly from said sleeve through said knob.

3. The invention as set forth in claim 1 in which said first and second blades are spring-biased toward each other, and the spring tension on the blade engageable with the pin holds said pin in engagement with said cam.

4. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and projecting outwardly from one end thereof for engagement with one of said first and second blades to vary the position of the contacts with each other upon adjustment of said sleeve, the end of the sleeve opposite its said one end being bifurcated, a control knob mounted on the bifurcated sleeve end, and a cam swingably mounted in said bifurcated sleeve end having a cam nose engageable with said pin and an arm projecting outwardly through said control knob, said cam being swingable to move said pin to cause it to move one of said first and and second blades to vary the position of the contacts with rEspect to each other irrespective of the adjusting movements of the sleeve.

5. The invention as set forth in claim 4 in which said control knob has an elongated slot formed therein, and said cam arm is slidably carried in said slot.

6. An electric switch, comprising a base, first and second blades mounted on said base and having a pair of contacts mounted thereon, a bimetallic blade mounted on said base and engageable with one of said first and second blades to vary the position of said contacts with respect to each other, a rigid arm mounted on said base, a sleeve adjustably movable on said arm, a pin of insulating material slidably carried in said sleeve and movable with and with respect to said sleeve, said pin being engageable with one of said first and second blades to vary the position of said contacts with respect to each other upon movement of said pin with and with respect to said sleeve, and means projecting outwardly from said sleeve and engaging said pin for sliding pin outwardly with respect to said sleeve toward said first or second blade engaging said pin, said first or second blade said pin urging said pin into engagement with said means whereby said pin is releasably retained in position with respect to said sleeve by said means and said first or second blade engaging said pin.

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