CIRCUIT BREAKER SWITCH
United States Patent 3686601
A push-pull snap action electrical switch including a longitudinally reciprocal shaft arranged to move at least two contact elements into and out of engagement with one another. The contact elements are inherently resilient leaf spring, at least one of which is biased into operative position by means of a thermal responsive element. The thermal responsive element is deflectable out of biasing position due to excess current flowing through it to allow disengagement of the contacts. Snap action is provided by spring means which may be movably mounted within a casing which is threadably or frictionally secured to the switch housing.
US Patent References:
Locking push button mechanism
Wirsching - February 1959 - 2873334
Switch assembly
Jones - April 1958 - 2832851
Electric switch
Kalwo - August 1957 - 2802082
Thermal cutout switches
Marcoz - December 1951 - 2577425
Electric switch
Whyte et al. - July 1947 - 2424527
Locking push button mechanism
Wirsching - February 1959 - 2873334
Switch assembly
Jones - April 1958 - 2832851
Electric switch
Kalwo - August 1957 - 2802082
Thermal cutout switches
Marcoz - December 1951 - 2577425
Electric switch
Whyte et al. - July 1947 - 2424527
Inventors:
Kaczmarek, Bernard (Chicago, IL)
Lander, Vern (Sarasota, FL)
Lander, Vern (Sarasota, FL)
Application Number:
05/052591
Publication Date:
08/22/1972
Filing Date:
07/06/1970
View Patent Images:
Export Citation:
Assignee:
Workman Electronic Products, Incorporated (Sarasota, FL)
Primary Class:
Other Classes:
200/523, 337/343, 200/325
International Classes:
H01H13/26; H01H15/10; H01H73/30; H01H15/00; H01H73/00; H01H13/50; H01H73/30; H01H3/12
Field of Search:
337/53,55,56,57,89,91,343,345,346,347,365,367,368,376,74,348,72,3,66 338/479,157 200/3,159A,169PB,153LB
US Patent References:
| 2293382 | Thermal type overload circuit breaker | August 1942 | Case et al. | |
| 1076896 | October 1913 | Lee | ||
| 2714644 | Thermostat apparatus | August 1955 | Harrison | |
| 3379843 | Simplified circuit breaker device with manual on-off control and manual reset | April 1968 | Shaffer et al. | |
| 2558908 | Circuit breaker switch | July 1951 | Paige | |
| 1930980 | Variable electrical resistor and switch | October 1933 | Maibohn | |
| 3354731 | Plunger actuated switch | November 1967 | Kussmaul | |
| 3081388 | Thermostatic controls | March 1963 | Cox | |
| 2320355 | Circuit breaker | June 1943 | Frank et al. | |
| 2488049 | Thermostatic switch | November 1949 | Bolesky | |
| 1492967 | Automatic cut-out | May 1924 | Donle | |
| 3236971 | Combination on-off switch and circuit-breaker | February 1966 | Cotsworth |
Primary Examiner:
Gilheany, Bernard A.
Assistant Examiner:
Morgan, Dewitt M.
Claims:
What is claimed is
1. An electric switch comprising: a housing, a pair of flexible, resilient contact elements movably mounted on said housing in cooperating relation to one another, reciprocating shaft means having a contact engaging head movably mounted in said housing, said head comprising a plurality of contact engaging surfaces each of which is oriented to engage one of said contact elements, whereby said contact elements are positioned in operative relation to one another upon movement of said shaft means; locking means mounted in cooperative engagement with said reciprocating shaft to maintain it in a predetermined position relative to said contact elements, and thermal responsive means mounted in direct biasing engagement to at least one of said contact elements so as to maintain it in operative relation to the other of said elements.
2. An electrical switch as defined in claim 1 wherein said thermal responsive means is positioned to move out of biasing relation to said flexible, resilient contact element upon reaching a predetermined temperature, whereby said flexible, resilient contact is deflected out of operative relation to the other of said flexible, resilient contact element.
3. An electrical switch as in claim 1 wherein said locking means comprises a spring strip secured to said shaft means, each extremity of said strip including an aperture positioned in surrounding relation to connector means supported by said housing and dimensioned to allow movement of the extremities of said strip to move relative to said connectors, whereby said strip is movably attached to said housing such that longitudinal movement of said reciprocating shaft means causes movement of each extremity of said strip relative to said housing.
4. An electrical switch as in claim 1 wherein said locking means comprises a detent means disposed within said housing adjacent to said head, said head further including a plurality of detent engaging surfaces formed thereon in cooperative position relative to said detent such that reciprocation of said shaft means causes engagement and disengagement between said detent means and said reciprocating shaft means, whereby snap action movement is imparted to said reciprocating shaft means wherein in said reciprocating shaft means is moved into and out of operative position relative to said flexible, resilient contact elements.
5. An electrical switch as in claim 1 comprising of a casing arranged to at least partially surround said locking means, attachment means for connecting said casing to said housing, wherein said locking means comprises a spring means secured between said shaft means and said casing and said attachment means assembly; said casing frictionally secured to said attachment means such that attachment and removal from said attachment means is accomplished due to inherent resiliency of said casing.
6. An electrical switch as in claim 5 wherein said locking means further comprises a restriction formed within said casing, and a lock ring attached to said reciprocating shaft means, said ring positioned on said shaft in relation to said restriction, whereby said reciprocating shaft means is maintained in a predetermined position at least partially due to cooperation of said locking ring with said restriction.
7. An electrical switch as in claim 1 further comprising a mechanical shaft moving means including cam means, said cam means including a plurality of camming surfaces the first of said camming surfaces movably engaging said reciprocating shaft means to move said contact elements into operative engagement with each other, and a second camming surface movably engaging said reciprocating shaft means to move said contact elements out of operative engagement with each other, whereby movement of said cam means causes the opening and closing of said contact elements.
1. An electric switch comprising: a housing, a pair of flexible, resilient contact elements movably mounted on said housing in cooperating relation to one another, reciprocating shaft means having a contact engaging head movably mounted in said housing, said head comprising a plurality of contact engaging surfaces each of which is oriented to engage one of said contact elements, whereby said contact elements are positioned in operative relation to one another upon movement of said shaft means; locking means mounted in cooperative engagement with said reciprocating shaft to maintain it in a predetermined position relative to said contact elements, and thermal responsive means mounted in direct biasing engagement to at least one of said contact elements so as to maintain it in operative relation to the other of said elements.
2. An electrical switch as defined in claim 1 wherein said thermal responsive means is positioned to move out of biasing relation to said flexible, resilient contact element upon reaching a predetermined temperature, whereby said flexible, resilient contact is deflected out of operative relation to the other of said flexible, resilient contact element.
3. An electrical switch as in claim 1 wherein said locking means comprises a spring strip secured to said shaft means, each extremity of said strip including an aperture positioned in surrounding relation to connector means supported by said housing and dimensioned to allow movement of the extremities of said strip to move relative to said connectors, whereby said strip is movably attached to said housing such that longitudinal movement of said reciprocating shaft means causes movement of each extremity of said strip relative to said housing.
4. An electrical switch as in claim 1 wherein said locking means comprises a detent means disposed within said housing adjacent to said head, said head further including a plurality of detent engaging surfaces formed thereon in cooperative position relative to said detent such that reciprocation of said shaft means causes engagement and disengagement between said detent means and said reciprocating shaft means, whereby snap action movement is imparted to said reciprocating shaft means wherein in said reciprocating shaft means is moved into and out of operative position relative to said flexible, resilient contact elements.
5. An electrical switch as in claim 1 comprising of a casing arranged to at least partially surround said locking means, attachment means for connecting said casing to said housing, wherein said locking means comprises a spring means secured between said shaft means and said casing and said attachment means assembly; said casing frictionally secured to said attachment means such that attachment and removal from said attachment means is accomplished due to inherent resiliency of said casing.
6. An electrical switch as in claim 5 wherein said locking means further comprises a restriction formed within said casing, and a lock ring attached to said reciprocating shaft means, said ring positioned on said shaft in relation to said restriction, whereby said reciprocating shaft means is maintained in a predetermined position at least partially due to cooperation of said locking ring with said restriction.
7. An electrical switch as in claim 1 further comprising a mechanical shaft moving means including cam means, said cam means including a plurality of camming surfaces the first of said camming surfaces movably engaging said reciprocating shaft means to move said contact elements into operative engagement with each other, and a second camming surface movably engaging said reciprocating shaft means to move said contact elements out of operative engagement with each other, whereby movement of said cam means causes the opening and closing of said contact elements.
Description:
This invention is directed to an electrical snap action switch having circuit breaker capabilities in the form of a thermal responsive element arranged to physically determine the position of at least one contact element relative to at least one other contact element so as to make or break the circuit of which the switch is a part.
In a number of conventional switches, opening or closing of the contacts usually occurs at a speed dependent upon the manual actuation of a push button or like activating element. When the contacts are slowly closed, a phenomenon known as arcing usually occurs between the contacts before they actually engage each other. The problem of arcing is particularly prevalent when the switch is operated at relatively high voltages. The occurrence of arcing and noise in conventional switches causes a rapid deterioration of the contacts and generally inefficient operation of the switch. Opening and closing of contacts at a consistent and acceptable rate minimizes arcing. Attempts to solve these problems have often resulted in relatively complex switch structures including numerous moving parts which are expensive and difficult to maintain and assemble.
A number of prior art switches are also designed to include an automatic circuit breaking capability during exposure to an overload current. One problem present in a number of these switches is the small amount of breaking power present in small automatic cut out switches. Larger circuit breakers utilize certain electro-magnetic means not practical in smaller switches because of additional expense and space requirements. Many of these presently known switches are quite complicated and include expensive linkages resulting in high manufacturing costs. Other switch structures can be maintained in a contact engaging position to overcome the circuit breaking feature of manually engaging forcing the contact elements. This defeats the purpose of automatic cut out switches by illuminating the safety feature necessary during an overload condition.
Accordingly, it is an object of the present invention to provide a reliable switch having a minimum amount of moving parts and being capable of operating with a snap action to minimize the problem of arcing and noise.
Another object is to provide an electrical switch having a circuit breaking feature by providing a thermal responsive element mounted adjacent to at least one of the contact elements so as to allow it to be deflected out of operative engagement with another contact when an overload occurs.
Still another object is to provide an electrical snap action switch combined with a thermal responsive element to provide the switch with a circuit breaking capability when an overload condition exists.
A further object is to provide a push button type switch wherein the speed in which the contacts engage and disengage is independent of the speed at which the push button is operated.
A still further object is to provide a switch including snap action spring means movably attached to the switch housing to provide an efficient snap action when the switch is moved between operative and inoperative positions.
Another object is to provide a switch wherein the spring means is partially surrounded by a casing resiliently and frictionally secured to the switch housing.
Another object is to provide a switch wherein the spring means is movably mounted within the casing which is threadably attached to the switch housing.
Another object is to provide an electrical switch including a longitudinally movable push button shaft positioned to move at least two contact elements into and out of operative engagement wherein the shaft may be reciprocally moved by means of a rotationally mounted cam means.
Another object is to provide an electrical snap action switch which further includes locking means to maintain the shaft in either operative or inoperative position in accordance with the force of the snap action spring also acting on the shaft.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
This invention is directed to an electrical switch of the snap action type including a shaft longitudinally movably in a reciprocal fashion either by manual operation of a push button or a rotary type activation means. The shaft is arranged on the switch housing in operative relation to at least two leaf spring contact elements. The contact elements are arranged such that longitudinal movement of the shaft allows the contact elements to move into engagement with one another due to their natural resiliency. The contact elements are disengaged by moving the shaft into engagement with at least one of the contact elements thereby forcing it against its natural bias.
This switch may further include a circuit breaker capability by mounting a thermal responsive element adjacent to at least one of the contact elements. The thermal responsive element may be in the form of a bimetal bar positioned to engage the contact element in a biasing relation. This contact element is positioned in operative relation to at least one other contact element. Movement of the shaft to an "on" position allows a contact element to move into engagement with the contact element biased in operative position by the bimetal bar. When the circuit of which the switch is a part is closed or completed, current flows through the bimetal bar. Overheating of the bimetal bar due to the flow of excess current causes it to be deflected out of engagement with the cooperating contact element. This contact element is thereby allowed to move out of engagement with the second contact element and the circuit is broken. The current then stops flowing through the bimetal bar thereby allowing it to cool and return to its normal contact element biasing position. The circuit may again be completed by activation of the shaft into and out of its "on-off" position. If excess current is still flowing through the circuit when the contact elements are again reengaged, the bimetal bar will again be deflected and the circuit will again be broken.
The switch further includes locking means which is arranged to maintain the shaft in its on or off position as desired. The locking means may include a spring detent positioned to cooperate with an extending lip or flange portion mounted on the shaft. Engagement of the detent and flange maintains the shaft against the biasing force of a coil spring mounted in concentric fashion about the shaft. Alternatively, the locking means may include a spring strip movably attached to the switch housing. The mid portion of the strip is attached to the shaft itself such that flexing of the strip provides a snap action to the shaft. The spring strip acts as a locking means due to its natural resiliency which maintains the shaft in the desired "on" or "off" position.
Snap action of the shaft may also be provided by a spring disc attached to the shaft and movably secured to the housing. The spring disc may also perform a locking function due to its natural resiliency acting against the force of a coil spring concentrically arranged about the shaft.
The spring disc may be partially surrounded by a casing having a hollow interior of sufficient size to allow for snap action of the disc. The casing may be attached to the housing of the switch by means of a bushing or similar attachment means. The casing and bushing may be threadably secured or alternately connected together by a quick disconnect frictional engagement due to the resiliency of the casing. Both of these means of securing the casing to the bushing enables rapid and efficient attachment and detachment from one another. A secure sealing relationship between the casing and bushing is also provided minimizing corrosion of the disc.
As pointed out above, engagement of the contacts is caused by longitudinal movement of the shaft. The shaft can be moved by either a push-pull or rotating type knob. Accordingly, one embodiment of the invention is directed to a cam means designed to cooperate with one extremity of the shaft or through a push button mounted thereon.
More specifically, the cam means comprises a first and second cam surface designed to rotate about an axis arranged substantially perpendicular to the axis of the shaft. The first cam surface cooperates with the bottom of a groove arranged in the push button. When the cam means rotates, the reciprocally mounted shaft is forced downward, thereby separating the contact elements. The second camming surface comprises an outwardly extending substantially helically arranged flange. This flange is positioned to cooperate with a lip or ledge arranged on the inner surface of the groove in the push button. Cooperation between the second camming surface and the lip during rotation of the camming means lifts the contact elements, due to their natural resiliency, to engage. The cooperation between the camming surfaces and the push button also overcomes the influence of the locking means on the shaft. Alternatively, the shaft moving means may comprise a conventional push-pull knob connected by a locking pin or the like to the push button or the extremity of the shaft itself. Therefore, another advantage of the present invention is its ability to cooperate with either a push-pull or a rotational control knob thereby making it readily adaptable for use on a variety of conventional appliances.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:
FIGS. 1-3 are cross sectional views of one embodiment of the present invention.
FIGS. 4 and 5 are sectional views of another embodiment of the present invention disclosing a snap action switch.
FIG. 6 is a top plan view of the attachment of the spring disc to the switch housing.
FIG. 7 is a sectional view of a casing structure partially surrounding the spring disc.
FIG. 8 is a sectional view of another embodiment of a casing structure partially surrounding the spring disc.
FIG. 9 is a sectional view of a rotational control knob serving to control engagement of the contact elements.
FIG. 10 is a side view of the rotational control knob of FIG. 9.
FIG. 11 is a sectional view of a push button control knob regulating the engagement of the contact elements.
Similar reference characters refer to similar parts throughout the several views of the drawings.
As shown in FIGS. 1-3, the switch device comprises a housing generally indicated as 10 in which are mounted at least two contact elements 12 and 14. These contact elements may be in the form of leaf springs so as to have an inherent resiliency. Leaf springs 12 and 14 are arranged in cooperating relationship with each other and with a longitudinally reciprocal shaft 16. Shaft 16 extends through cover plate 15 attached to housing 10 by screws 17. A contact engaging head 18 is affixed to the extremity of shaft 16 and includes outwardly extending fingers 20 and 22. A spring detent 24 is mounted within housing 10 to cooperate with finger 20 so as to maintain shaft 16 in depressed open circuit position relative to contact elements 12 and 14. A thermal responsive element in the form of bimetal 26 is arranged within housing 10 in biasing engagement with contact element 14. More specifically, contact element 14 is maintained in operative position relative to contact element 12 by bimetal 26. Movement of shaft 16 into operative position thereby causes engagement between contact elements 12 and 14 and completion of the circuit. As shown in FIG. 2, the downward movement of shaft 16 by means of push button 28 causes the lower extremity of head 18 to engage contact element 12 forcing it out of engagement with contact element 14. Detent 24 engages finger 20 so as to maintain shaft 16 against the biasing force exerted on shaft 16 by coil spring 30.
When it is desired to complete the circuit, shaft 16 is raised into operative position thereby allowing engagement of contact elements 12 and 14 as shown in FIG. 1. When an excess or overflow of current passes through the circuit, thermal responsive element 26 is overheated and accordingly moves out of biasing engagement with contact element 14. This in turn causes contact element 14 to be deflected, due to its inherent resiliency, out of cooperating relation and engagement with contact element 12 as shown in FIG. 3.
As shown in FIGS. 4 and 5, spring strip 32 is connected to shaft 16 and provides it with snap action during its longitudinal movement to engage and disengage contact elements 12 and 14. Spring strip 32 is secured to the housing 10 by means of screws 34 extending through the extremities of strip 32 into mounting bushings 36. As more specifically shown in FIG. 6, each extremity has an elongated slot 38 formed therein to allow relative movement between the strip 32 and the mounting brushing 36, during the snap action of strip 32 from the position shown in FIG. 4 to the contact disengagement position shown in FIG. 5. Strip 32 in addition to providing the snap action to shaft 16 also serves as a locking means to naturally bias shaft 16 in the desired position.
FIG. 7 discloses shaft 16 being moved with a snap action due to spring disc 40. A casing 42 is attached to the cover plate 15 of housing 10 by an attachment means in the form of a bushing 44. Casing 42 frictionally engages bushing 44 so as to partially surround spring disc 40 which is positioned within the hollow interior 46. Casing 42 may be made of a plastic or like elastic material such that it is inherently resilient and consequently may be quickly attached or detached to bushing 44. This engagement also provides a secure sealing engagement with bushing 44 thereby prohibiting exposure of spring disc 40 from any corrosive environment. Shaft 16 is maintained in either operative or inoperative position partially due to the natural bias of spring disc 40 and also due to the cooperation of lock ring 48 with restriction 50 on the interior of casing 42. Both the spring disc 40 and lock ring 50 may serve as a locking means acting against the bias of spring 30 thereby maintaining shaft 16 in a desired position.
Similarly FIG. 8 shows casing 42 being threadably attached at 52 to bushing 44 in order to provide a sealed enclosure for spring disc 40. The extremity or periphery 54 of spring disc 40 is movably positioned between casing 42 and bushing 44 in order to provide for the necessary play during snap action.
FIGS. 9 and 10 disclose a shaft moving means comprising a rotatable control shaft 56 threadably attached to support bushing 58 securing shaft 56 to base plate 60. A potentiometer or like device may be substituted for bushing 58. A cam means generally indicated as 62 is attached to one extremity of shaft 56 and includes a first and second cam surfaces 64 and 66, respectively. Camming means 62 is positioned to cooperate with push button 68 which includes groove 70 and inwardly extending lip 72. More specifically, the first cam surface 64 comprises the peripheral surface of disc 74 and is positioned to engage bottom 76 of groove 70 so as to depress shaft 60 during rotation of shaft 56. Shaft 16 is raised into contact making position through the cooperation of the second helically shaped cam surface 66 cooperating with lip 72 within groove 70.
FIG. 11 is directed to a second shaft moving means comprising a push-pull type plunger generally indicated as 78 and including shaft 80 cooperating with mounting bushing 58 which in turn is secured to mounting plate 82. The lower extremity of shaft 80 is secured to push button 84 by means of locking ring 86 fitted in annular groove 88. The reciprocal movement of shaft 16 is accomplished by a push-pull action on shaft 80 in order to make or break contact element 12 and 14.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in carrying out the above method and article without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.
Now that the invention has been described,
In a number of conventional switches, opening or closing of the contacts usually occurs at a speed dependent upon the manual actuation of a push button or like activating element. When the contacts are slowly closed, a phenomenon known as arcing usually occurs between the contacts before they actually engage each other. The problem of arcing is particularly prevalent when the switch is operated at relatively high voltages. The occurrence of arcing and noise in conventional switches causes a rapid deterioration of the contacts and generally inefficient operation of the switch. Opening and closing of contacts at a consistent and acceptable rate minimizes arcing. Attempts to solve these problems have often resulted in relatively complex switch structures including numerous moving parts which are expensive and difficult to maintain and assemble.
A number of prior art switches are also designed to include an automatic circuit breaking capability during exposure to an overload current. One problem present in a number of these switches is the small amount of breaking power present in small automatic cut out switches. Larger circuit breakers utilize certain electro-magnetic means not practical in smaller switches because of additional expense and space requirements. Many of these presently known switches are quite complicated and include expensive linkages resulting in high manufacturing costs. Other switch structures can be maintained in a contact engaging position to overcome the circuit breaking feature of manually engaging forcing the contact elements. This defeats the purpose of automatic cut out switches by illuminating the safety feature necessary during an overload condition.
Accordingly, it is an object of the present invention to provide a reliable switch having a minimum amount of moving parts and being capable of operating with a snap action to minimize the problem of arcing and noise.
Another object is to provide an electrical switch having a circuit breaking feature by providing a thermal responsive element mounted adjacent to at least one of the contact elements so as to allow it to be deflected out of operative engagement with another contact when an overload occurs.
Still another object is to provide an electrical snap action switch combined with a thermal responsive element to provide the switch with a circuit breaking capability when an overload condition exists.
A further object is to provide a push button type switch wherein the speed in which the contacts engage and disengage is independent of the speed at which the push button is operated.
A still further object is to provide a switch including snap action spring means movably attached to the switch housing to provide an efficient snap action when the switch is moved between operative and inoperative positions.
Another object is to provide a switch wherein the spring means is partially surrounded by a casing resiliently and frictionally secured to the switch housing.
Another object is to provide a switch wherein the spring means is movably mounted within the casing which is threadably attached to the switch housing.
Another object is to provide an electrical switch including a longitudinally movable push button shaft positioned to move at least two contact elements into and out of operative engagement wherein the shaft may be reciprocally moved by means of a rotationally mounted cam means.
Another object is to provide an electrical snap action switch which further includes locking means to maintain the shaft in either operative or inoperative position in accordance with the force of the snap action spring also acting on the shaft.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
This invention is directed to an electrical switch of the snap action type including a shaft longitudinally movably in a reciprocal fashion either by manual operation of a push button or a rotary type activation means. The shaft is arranged on the switch housing in operative relation to at least two leaf spring contact elements. The contact elements are arranged such that longitudinal movement of the shaft allows the contact elements to move into engagement with one another due to their natural resiliency. The contact elements are disengaged by moving the shaft into engagement with at least one of the contact elements thereby forcing it against its natural bias.
This switch may further include a circuit breaker capability by mounting a thermal responsive element adjacent to at least one of the contact elements. The thermal responsive element may be in the form of a bimetal bar positioned to engage the contact element in a biasing relation. This contact element is positioned in operative relation to at least one other contact element. Movement of the shaft to an "on" position allows a contact element to move into engagement with the contact element biased in operative position by the bimetal bar. When the circuit of which the switch is a part is closed or completed, current flows through the bimetal bar. Overheating of the bimetal bar due to the flow of excess current causes it to be deflected out of engagement with the cooperating contact element. This contact element is thereby allowed to move out of engagement with the second contact element and the circuit is broken. The current then stops flowing through the bimetal bar thereby allowing it to cool and return to its normal contact element biasing position. The circuit may again be completed by activation of the shaft into and out of its "on-off" position. If excess current is still flowing through the circuit when the contact elements are again reengaged, the bimetal bar will again be deflected and the circuit will again be broken.
The switch further includes locking means which is arranged to maintain the shaft in its on or off position as desired. The locking means may include a spring detent positioned to cooperate with an extending lip or flange portion mounted on the shaft. Engagement of the detent and flange maintains the shaft against the biasing force of a coil spring mounted in concentric fashion about the shaft. Alternatively, the locking means may include a spring strip movably attached to the switch housing. The mid portion of the strip is attached to the shaft itself such that flexing of the strip provides a snap action to the shaft. The spring strip acts as a locking means due to its natural resiliency which maintains the shaft in the desired "on" or "off" position.
Snap action of the shaft may also be provided by a spring disc attached to the shaft and movably secured to the housing. The spring disc may also perform a locking function due to its natural resiliency acting against the force of a coil spring concentrically arranged about the shaft.
The spring disc may be partially surrounded by a casing having a hollow interior of sufficient size to allow for snap action of the disc. The casing may be attached to the housing of the switch by means of a bushing or similar attachment means. The casing and bushing may be threadably secured or alternately connected together by a quick disconnect frictional engagement due to the resiliency of the casing. Both of these means of securing the casing to the bushing enables rapid and efficient attachment and detachment from one another. A secure sealing relationship between the casing and bushing is also provided minimizing corrosion of the disc.
As pointed out above, engagement of the contacts is caused by longitudinal movement of the shaft. The shaft can be moved by either a push-pull or rotating type knob. Accordingly, one embodiment of the invention is directed to a cam means designed to cooperate with one extremity of the shaft or through a push button mounted thereon.
More specifically, the cam means comprises a first and second cam surface designed to rotate about an axis arranged substantially perpendicular to the axis of the shaft. The first cam surface cooperates with the bottom of a groove arranged in the push button. When the cam means rotates, the reciprocally mounted shaft is forced downward, thereby separating the contact elements. The second camming surface comprises an outwardly extending substantially helically arranged flange. This flange is positioned to cooperate with a lip or ledge arranged on the inner surface of the groove in the push button. Cooperation between the second camming surface and the lip during rotation of the camming means lifts the contact elements, due to their natural resiliency, to engage. The cooperation between the camming surfaces and the push button also overcomes the influence of the locking means on the shaft. Alternatively, the shaft moving means may comprise a conventional push-pull knob connected by a locking pin or the like to the push button or the extremity of the shaft itself. Therefore, another advantage of the present invention is its ability to cooperate with either a push-pull or a rotational control knob thereby making it readily adaptable for use on a variety of conventional appliances.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:
FIGS. 1-3 are cross sectional views of one embodiment of the present invention.
FIGS. 4 and 5 are sectional views of another embodiment of the present invention disclosing a snap action switch.
FIG. 6 is a top plan view of the attachment of the spring disc to the switch housing.
FIG. 7 is a sectional view of a casing structure partially surrounding the spring disc.
FIG. 8 is a sectional view of another embodiment of a casing structure partially surrounding the spring disc.
FIG. 9 is a sectional view of a rotational control knob serving to control engagement of the contact elements.
FIG. 10 is a side view of the rotational control knob of FIG. 9.
FIG. 11 is a sectional view of a push button control knob regulating the engagement of the contact elements.
Similar reference characters refer to similar parts throughout the several views of the drawings.
As shown in FIGS. 1-3, the switch device comprises a housing generally indicated as 10 in which are mounted at least two contact elements 12 and 14. These contact elements may be in the form of leaf springs so as to have an inherent resiliency. Leaf springs 12 and 14 are arranged in cooperating relationship with each other and with a longitudinally reciprocal shaft 16. Shaft 16 extends through cover plate 15 attached to housing 10 by screws 17. A contact engaging head 18 is affixed to the extremity of shaft 16 and includes outwardly extending fingers 20 and 22. A spring detent 24 is mounted within housing 10 to cooperate with finger 20 so as to maintain shaft 16 in depressed open circuit position relative to contact elements 12 and 14. A thermal responsive element in the form of bimetal 26 is arranged within housing 10 in biasing engagement with contact element 14. More specifically, contact element 14 is maintained in operative position relative to contact element 12 by bimetal 26. Movement of shaft 16 into operative position thereby causes engagement between contact elements 12 and 14 and completion of the circuit. As shown in FIG. 2, the downward movement of shaft 16 by means of push button 28 causes the lower extremity of head 18 to engage contact element 12 forcing it out of engagement with contact element 14. Detent 24 engages finger 20 so as to maintain shaft 16 against the biasing force exerted on shaft 16 by coil spring 30.
When it is desired to complete the circuit, shaft 16 is raised into operative position thereby allowing engagement of contact elements 12 and 14 as shown in FIG. 1. When an excess or overflow of current passes through the circuit, thermal responsive element 26 is overheated and accordingly moves out of biasing engagement with contact element 14. This in turn causes contact element 14 to be deflected, due to its inherent resiliency, out of cooperating relation and engagement with contact element 12 as shown in FIG. 3.
As shown in FIGS. 4 and 5, spring strip 32 is connected to shaft 16 and provides it with snap action during its longitudinal movement to engage and disengage contact elements 12 and 14. Spring strip 32 is secured to the housing 10 by means of screws 34 extending through the extremities of strip 32 into mounting bushings 36. As more specifically shown in FIG. 6, each extremity has an elongated slot 38 formed therein to allow relative movement between the strip 32 and the mounting brushing 36, during the snap action of strip 32 from the position shown in FIG. 4 to the contact disengagement position shown in FIG. 5. Strip 32 in addition to providing the snap action to shaft 16 also serves as a locking means to naturally bias shaft 16 in the desired position.
FIG. 7 discloses shaft 16 being moved with a snap action due to spring disc 40. A casing 42 is attached to the cover plate 15 of housing 10 by an attachment means in the form of a bushing 44. Casing 42 frictionally engages bushing 44 so as to partially surround spring disc 40 which is positioned within the hollow interior 46. Casing 42 may be made of a plastic or like elastic material such that it is inherently resilient and consequently may be quickly attached or detached to bushing 44. This engagement also provides a secure sealing engagement with bushing 44 thereby prohibiting exposure of spring disc 40 from any corrosive environment. Shaft 16 is maintained in either operative or inoperative position partially due to the natural bias of spring disc 40 and also due to the cooperation of lock ring 48 with restriction 50 on the interior of casing 42. Both the spring disc 40 and lock ring 50 may serve as a locking means acting against the bias of spring 30 thereby maintaining shaft 16 in a desired position.
Similarly FIG. 8 shows casing 42 being threadably attached at 52 to bushing 44 in order to provide a sealed enclosure for spring disc 40. The extremity or periphery 54 of spring disc 40 is movably positioned between casing 42 and bushing 44 in order to provide for the necessary play during snap action.
FIGS. 9 and 10 disclose a shaft moving means comprising a rotatable control shaft 56 threadably attached to support bushing 58 securing shaft 56 to base plate 60. A potentiometer or like device may be substituted for bushing 58. A cam means generally indicated as 62 is attached to one extremity of shaft 56 and includes a first and second cam surfaces 64 and 66, respectively. Camming means 62 is positioned to cooperate with push button 68 which includes groove 70 and inwardly extending lip 72. More specifically, the first cam surface 64 comprises the peripheral surface of disc 74 and is positioned to engage bottom 76 of groove 70 so as to depress shaft 60 during rotation of shaft 56. Shaft 16 is raised into contact making position through the cooperation of the second helically shaped cam surface 66 cooperating with lip 72 within groove 70.
FIG. 11 is directed to a second shaft moving means comprising a push-pull type plunger generally indicated as 78 and including shaft 80 cooperating with mounting bushing 58 which in turn is secured to mounting plate 82. The lower extremity of shaft 80 is secured to push button 84 by means of locking ring 86 fitted in annular groove 88. The reciprocal movement of shaft 16 is accomplished by a push-pull action on shaft 80 in order to make or break contact element 12 and 14.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in carrying out the above method and article without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.
Now that the invention has been described,