US2458807A - Thermostatic switch - Google Patents

Description

Jan. 11, 1949. J. w. TUCKER 2,458,807

THERMOSTATIC SWITCH Filed July 16, 1945 65 Izdeniof' I Lfo/lz /1. YZzc/lfer wmww Patented Jan. 11, 1949 THERMOSTATIC SWITCH John W. Tucker, Peotone, Ill., assignor to Hopax Industries, Inc., Chicago, Ill., a corporation of --Illinois Application July 16, 1945, Serial No. 605,219

This invention relates to thermostatic switches and more particularly to those of the type which are both manually and thermostatically operable.

It is a general object of the present invention to provide an improved thermostatic switch adapted to complete manual operation for opening and closing an electrical circuit, as well as to thermostatically controlled automatic operation for opening the circuit.

Another object of the invention is to provide a thermostatically and manually operable switch wherein the parts are constructed and arranged so that vibration and/or jarring do not materially affect the operation of the switch.

The invention has for a furtherobject the provision of a rugged and light weight switch incorporating a latch type holding mechanism manually operable to open and close the switch contacts and automatically operable in response to flexure of a bimetallic element to open the contacts.

Compactness, freedom from complicated or particularly delicate parts, ease of manufacture and assembly of parts, capability of uniform manufacture in mass production, and lack of the necessity of close and frequent adjustments are among the features coming within the purview of my present invention.

Other objects and advantages of the invention will be apparent from'the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the single sheet of drawings:

Fig. 1 is a perspective view of a switch embodying my invention in a preferred form;

Fig. 2 is a side sectional view of the switch shown in Fig. l with the section taken substantially on the line 2-4 of Fig. 1 and viewed in the direction indicated by the arrows; the operating parts of the switch being shown in their normal positions;

Fig. 3 is a sectional plan view of the switch shown in Fig. 1 with the section taken substantially on a line 3-4 of Fig. 1;

Fig. 4 is a fragmentary view similar to Fig. 2, but indicating portions of the operating parts in diflerent positions of operation than those de-' picted in Fig. 2; and

Fig. 5 is a perspective view oi'- some of the switch parts and illustrates the electrical circuit of the switch.

Referring to the drawings. the thermostatic switch therein illustrated constitutes an exemplary or illustrative embodiment of my inven- 6 Claims. (Cl. 200-116) tion. In this exemplary form, the switch has a base M which is desirably made of molded insulating material such as phenol fiber and includes integrally formed end walls I! and it projecting in parallel relationship to each other and in perpendicular relationship to opposite ends of a bottom portion ll of the base.

A stationary contact I! has a contact portion l6 and a threaded stem portion i1 and is located near the end wall I! of the base. The head portion it of the contact is located by a boss it formed integrally with the base while the stem portion l1 extends through a suitable opening I! in the base and serves to hold and make electrical connection with a switch terminal 20 on the outer surface of the base.

At the other end of the base and near the end wall It, a support bracket 22 is secured to the inner surface of the base by fastening means such as a screw 23 which is threaded into the base. A resilient contact carrying arm 24 is secured at one end to the support bracket 22 by fastening means such as a screw 25 and extends to a position near the head portion It of the stationary contact. At its extending end the resilient contact carrying arm has secured thereto a contact 26 normally spaced from the contact l5 and in alignment for engagement therewith upon flexure of the contact carrying arm. Intermediate its ends the contact carrying arm has a.

longitudinal slot 21 therein which provides a latching shoulder 28.

A latch member 29 having angularly disposed portions 30 and 32 has an end portion 33 disposed in a slot 34 in the base and is supported for rotational swinging movement by means such as a pin 35. The angularly projecting portion 32 of the latch member has one edge shaped to provide a latching shoulder 30 and cam surfaces 31 and 38. The end of the projecting portion 32 adJacent the latching shoulder and cam surfaces extends through the slot 21' in the contact carrying arm so. that the latching shoulder 33 is adapted to engage the latching edge 2! of the contact carrying arm to hold the contacts I! and It in engagement as shown in Fig. 4.

A spring 39 is disposed in a recess ll between the base II and the projecting end I. of the latch member to bias the latch member about its rotational support pin 35 to the latching position. Normally, when the contacts are in the open position, the cam surface I! engages the latching edge 18 to hold the latch member in a predetermined released position. The cam surface 31 is angularly disposed with respect to the latching In the disclosed embodiment the side walls of the housing have end flanges 45 and the front face is provided with end flanges 46 which fit over the end walls l2 and I3 of the base to hold the housing in position relative to the base.

Desirably at the mid portion of the front face 43 of the housing, a laterally disposed sleeve 41 is secured in an aperture 48 and extends through the front face to provide a support for amanually operable actuating member 49. The actuating member 49 is carried by the sleeve for linear sliding movement relative thereto toward and away from the resilient contact carrying arm 24. Undesired removal of the actuating member from the sleeve is prevented by removable fastening means exemplified in the present instance by a resilient c-clip 50 mounted in a suitable groove near the inner end of the actuating member.

Projecting axiallyfrom the inner end of the actuating member 49 is an integral switch actuating stud 52 having an end surface 53 and an angularly disposed cam surface 54; the angularity of the cam surface being such that it extends outwardly toward the'end surface 53 to define a peripheral groove between it and an end shoulder of the actuating member. The lateral dimensions of the switch actuating stud are such that upon inward movement of the actuating member from the normal position shown in Fig. 2, the stud passes the extending end of the projecting portion 32 of the latch member.

A resilient leaf spring 55 has one end anchored adjacent the anchored end of the contact carrying arm and desirably by the same fastening means, such as the screw 25. This leaf spring overlies the surface of the contact carryingarm 24 and has an end portion normally extending angularly away from the surface of the contact carrying arm and into engagement with the end surface 53 (f the switch actuating stud to bias the actuating member to a normal position such that the outer end of the actuating member is extended and the end surface 53 of the actuating stud is spaced from the contactcarrying arm.

Manually effected inward movement of the actuating member flexes the leaf spring 55 toward and into engagement with the contact carrying arm 24 and then flexes the contact carrying arm to a position such as that indicated in Fig. 4 in which the latching shoulder 36 is biased into holding engagement with the latching edge 28. During the inward movement of the actuating member the actuatingstud 52 passes the end of the projecting portion 32 of the latch member and moves toa position such that when the latching shoulder 35 engages the latching edge 28, the cam surface 38 on the projecting portion 32 of the latch member engages the cam surface 54 on the of the actuating member.

'In addition to the manual operation of the *switch for effecting either engagement or disengagement of the contacts, the disclosed switch is adapted to be thermostatically released to open the contacts in response to flexure of a bi-metallic temperature responsive element 56. By preference the bl-metallic element 56 is substantially U-shaped, having side legs 51 and 58 and a connecting portion 59 at one end. The side leg 51 has the end opposite the connecting portion 53 secured to the support bracket 22 by fastening means such as a, rivet 60. The corresponding end of the other side leg 58 is anchored to the base by fastening means such as a screw 52 which extends through the base and is threaded into a switch terminal 63 on the outer surface of the base. The connecting portion 59 of the bi-metallic element overlies the projecting portion 30 of the latch member and has strips 64 of insulating material secured thereto to prevent electrical contact of the bi-metallic .element with either the latch member 29 or the contact carrying arm 24 during the operation of the switch.

As illustrated in Fig. 5, the bi-metallic element 56, in the present instance, is connected in series with the contact carrying arm 24 and serves as a part of the electrical circuit through the switch. It is understood, of course, that the bi-metallic element might be indirectly heated or responsive to any desired controlling temperature. When connected as shown, predetermined heating of the bi-metallic element due to current flow therethrough produces flexure of that element toward the projecting portion 30 of the latch member and upon engagement with that portion of the latch member and continued flexure of the bi-metallic element, the latch member is moved against the biasing force of the spring 39 to effect the automatic release of the contact carrying arm from the circuit closing position. After release of the latch member by the bi-metallic element, the contact carrying arm cannot be relatche'd in the contact closing position until the bi-metallic element has cooled off enough to return to its normal position and thereby release the latch member.

When the switch is assembled, the main operating parts of the switch, including the contacts, contact carrying arm and the bi-metallic element, are secured in their operating positions on the base. The actuating member 49 is assembled with the housing. When the housing is assembled with respect to the base, sheets of insulating material H are desirably placed within the sides of the housing to prevent any possibility of contact of the electrically conductive parts of the switch with the metallic housing, For mounting the switch relative to a panel or the like, threaded bushings 65 are secured to and open outwardly from the front face of the housing.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

' 1. A thermostatic switch comprising, in combination, a base of insulating material having integral end walls projecting therefrom, astationary contact secured to the base near one of the end walls, a switch terminal electrically connected to the stationary contact, a metallic contact support bracket secured to the base near the other of the end walls, a resilient contact arm secured at one end to the support bracket and having a contact on the other end normally spaced from and aligned for engagement with the stationary contact, said contact arm having a longitudinally elongated slot in the mid-portion thereof, a resilient leaf spring element overlying the secured end of the contact arm and extending along the contact arm in normal angularly spaced relation thereto, a substantially U- shaped bimetallic element having side legs and a connecting portion 'spaced'from the contact arm, one of said side legs having an end anchored to the support bracket and the other of said legs having its adjacent end secured to the base, a second switch terminal electrically connected to the last mentioned leg of the bimetallic element, a latch member rotatably secured to the base and having a shoulder underlying the connecting portion of the bimetallic element and a latch tang extending between said legs and through said slot in the contact arm, said latch tang having a shoulder adapted to engage said contact arm to hold the contacts in engagement and a cam surface, a spring biasing the latch member toward the contact holding position, said connecting portion being adapted to engage the first mentioned shoulder upon flexure of the bimetallic element to move the latch member from the contact holding position against the biasing force of said spring, a switch housing carried by the base, a manually operable actuating element car'- ried by the housing for linear movement toward a and from the contact arm against the force of said leaf spring element, said actuating element having an end adapted to force the contact arm to position for engagement by the latch member, and said actuating element having a cam surface adapted to be engaged by the latch tang for effecting release of the latch member from the contact arm upon manual movement of the actuating member away from the contact arm.

2. A thermostatic switch comprising, in combination, a base of insulating material, a pair of switch terminals, a s tionary contact secured to the base and electric y connected to one of the terminals, an electrically conductive contact support bracket secured to the other end of the base, a resilient contact carrying arm anchored at one end to the support bracket and carrying a contact in alignment for engagement with the stationary contact, a resilient leaf spring anchored at the anchored end of the contact arm and extending therealong in normal angularly disposed relationship thereto, said leaf spring being flexible toward and from the contact arm, a substantially U-shaped. bimetallic element having side legs and a connecting portion, the ends of said legs remote from the connecting portion being anchored and electrically connected to the contact arm and the other of said terminals, a,

latch member movably secured to the base and having parts, one of which is adapted to coact with the contact arm to hold the contacts in engagement and the other of which is in alignment with the connecting portion of the bimetallic element, a spring biasing the latch member to the contact holding position, insulating means on said connecting portion adapted to engage the latch member upon flexure of the bimetallic element to move said latch member from the contact holding position, a housing carried by the base, a manually operable actuating element movably carried by the housing and having a part engaging said leaf spring and adapted'weifecrengagementofthecontacts, and said actuating element having means thereon for engaging and effecting release of the latch member upon manual movement of the actuating element away from the contact arm.

3. A thermostatic switch comprising, in combination, a base of insulating material, a pair of switch terminals, a pair of normally separated contacts aligned for engagement, one of said contacts being carried by a resilient contact carrying arm,- and the other of said contacts being electrically connected to one of the switch terminals, said resilient contact carrying arm having one end anchored and having a'slot intermediate the anchored'end and the contact carried thereby, a latch member supported for swingingmovement relative to the base and having two angularly disposed projecting portions, one of said portions projecting through said slot and having a latching surface adapted to engage the contact carrying arm to hold the contacts in engagement, a spring biasing the latch member in a direction to effect engagement of the latching surface with the contact carrying arm, a thermostatic element secured to the base and adapted under predetermined conditions to effect movement of the latching member against the biasing force of said spring to effect release of the contact carrying arm-from the latching surface, a housing mounted on the base. a manually operable switch actuating member movably carried by the housing and having a portion adapted to force the contact carrying arm in one direction to effect engagement of the contacts upon manual movement thereof, and said latch member and actuating member having coacting cam surfaces adapted to interlock upon movement of the actuating member to effect engagement of the contacts, said interlocked cam surfaces being effective to release the latch member from the contact carrying arm upon manual movement of the actuating member in the opposite direction. we 7 4. A thermostatic switch comprising, in com bination, a base of insulating material, a. pair of normally separated contacts mounted relative to said base and in alignment for engagement, one oPsaid contacts being supported for movement toward and from the other by a resilient contact carrying arm, said contact carrying arm having a latching edge intermediate the ends thereof, a latching member supported for swinging movement relative to said base and having a portion movable toward and from said latching edge, said portion including a latching shoulder adapted to engage the contact carrying arm to hold the contacts in engagement andcam surfaces adjacent the latching shoulder angularly disposed relative to one another and to said shoulder, one of said cam surfaces being normally in alignment for engagement with said latching edge and the other extending beyond the latching edge, a spring liasing the latching member in one direction to urge said portion toward the contact carrying arm, a thermostatic member for effecting automatic release of the contact carrying arm from the latch member, an actuating member supported for movement toward and from the contact carrying arm for effecting engagement and disengagement of the contacts, means biasing the actuating member away from the contact carrying am, said actuating member and the latch member being normally disengaged, and said actuating member having a cam surface thereon adapted to be engaged by said extending cam surface of the latch member when the latching shoulder is in engagement with the latching edge, the engaging cam surfaces of theactuating and latch members being so disposed as to effect release of the latching edge from the latching shoulder upon manual movement 01 the actuating member away from the contactcarrying arm.

5.. A thermostatic switch comprising, in combination, a base, a pair of relatively movable contacts aligned for engagement, means biasing the contacts apart, latch means movably supported and having a latching position for holding said contacts in engagement, means biasing the latch means toward said latching position, thermostatic means for effecting movement of the latch means away from the latching position, and a manually operable actuating member movably supported in a position for coaction with one of said contacts and with said latch means, said actuating member including a cam portion and a portion for etfecting engagement of the contacts upon movement in one direction, said latch means including a cam portion coacting with the cam portion of the actuating member when the contacts are closed and operable to move the latch means away from the latching position upon movement of the actuating member in the opposite direction.

6. A thermostatic switch comprising, in combination, support means, a pair of relatively movable contacts having open and closed positions,

toward the latching position, th ermostatie means for moving the latch means away from the latching position, cam means on the latch means coacting with one of said contacts normally to hold the latch means away from the latching'position, and a manually operable actuating means having switch opening and closing positions and adapted to ooact' with one of said contacts and the latch means, means biasing the actuating means to the switch opening position, said actuating means including a portion for moving the contacts to the closed position and an angularly disposed cam surface, and said latch means including a portion adapted to engage the cam surface when the latch means is in the latching position to retain the actuating means in the switch closing position, and said angularly disposed cam surface eiiecting movement of the latch means from the latching position when the actuating means is manually moved to the switch opening position.

JOHN W. TUCKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,232,458 Cavanagh July 3, 1917 1,877,058 Schmid Sept. 13, 1932 1,896,736 Wilms Feb. '7, 1933 2,248,402 Conboy July 8, 1941 2,343,264 Platz Mar. 7, 1944

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