THERMOSTAT WITH MOUNTING MEANS
United States Patent 3827013
There is provided an improved snap disc-operated thermostat switch structure which is characterized by an improved disc retainer and slotted plate mounting structure. The improved disc retainer not only holds the body members together for enclosing the switch mechanism, terminals and leads, but includes slotted plate mounting means projecting outwardly therefrom for insertion into a slot in a plate, e.g., a sheet metal plate as a radiator housing, and snap locking engagement therewith. In more specific embodiments, resilient finger means are provided for coaction with the mounting means to hold the thermostat tightly against the slotted plate, for example, to prevent annoying rattling.
US Patent References:
Thermostatic controls
Cox - March 1963 - 3081388
Manual reset thermostatic control
Odson - November 1965 - 3219783
THERMOSTAT
Snider - October 1970 - 3537052
Thermostatic controls
Cox - March 1963 - 3081388
Manual reset thermostatic control
Odson - November 1965 - 3219783
THERMOSTAT
Snider - October 1970 - 3537052
Inventors:
Kowalski, Walter C. (Mansfield, OH)
Them, Edward G. (Mansfield, OH)
Them, Edward G. (Mansfield, OH)
Application Number:
05/378280
Publication Date:
07/30/1974
Filing Date:
07/11/1973
View Patent Images:
Export Citation:
Assignee:
Therm-O-Disc Incorporated (Mansfield, OH)
Primary Class:
Other Classes:
337/112, 337/372, 337/380
International Classes:
H01H37/54; H01H37/00; H01H37/52
Field of Search:
337/354,372,380,112,113,34
Primary Examiner:
Miller J. D.
Assistant Examiner:
Bell, Fred E.
Attorney, Agent or Firm:
McNenny, Farrington, Pearne & Gordon
Claims:
What is claimed is
1. A disc retainer and slotted plate mounting for a snap disc thermostat switch having a pair of nonconductive mating body sections and internal spaced electric terminals, said retainer comprising a shaped sheet metal body having:
2. an upstanding tab portion, and
3. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
4. A disc retainer and slotted plate mounting in accordance with claim 1 which also includes:
5. resilient finger means partially severed from and raised out of the plane of said planar body portion for urging a slotted plate away from said planar body portion and into contact with said free distal extremity.
6. A disc retainer and slotted plate mounting in accordance with claim 1 wherein the slotted plate mounting means includes a pair of upstanding tab portions each having resilient detent portions.
7. A disc retainer and slotted plate mounting in accordance with claim 1 wherein the rectangular planar body portion includes a centrally located aperture for exposing one surface of said snap disc.
8. A disc retainer and slotted plate mounting in accordance with claim 4 wherein the slotted plate mounting means includes a pair of upstanding tab portions disposed on opposite sides of said aperture, each of said tab portions having resilient detent portions.
9. In a thermostat having an elongated nonconductive body member formed with a lengthwise switch chamber open along one face thereof, first and second terminal units extending lengthwise of said chamber, a single rivet securing each terminal unit in said switch chamber, said terminal units including cooperating switch contacts, one of which is movable between a switch open and a switch closed position, a thermally responsive bimetallic snap disc, a bumper operably coacting between said movable switch contact and said disc to move said movable switch contact between open and closed positions in response to movement of said disc, a nonconductive cover member positioned over said one face of said switch chamber and cooperating with said body member to enclose said terminal units, the improvement which comprises a disc retainer and slotted plate mounting having:
10. an upstanding tab portion, and
11. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
12. In a thermostat having an elongated nonconductive body member formed with a lengthwise switch chamber open along one face thereof and including spaced rivet-receiving recesses extending inwardly from the bottom thereof, first and second terminal units extending lengthwise of said chamber, a single rivet securing each terminal unit in said switch chamber, one end of said rivet being exposed in its respective recess, said terminal units including cooperating switch contacts, one of which is movable between a switch open and a switch closed position, a thermally responsive bimetallic snap disc, a bumper operably coacting between said movable switch contact and said disc to move said movable switch contact between open and closed positions in response to movement of said disc, a nonconductive cover member positioned over said one face of said switch chamber and cooperating with said body member to enclose said terminal units, the improvement which comprises a disc retainer and slotted plate mounting having:
13. an upstanding tab portion, and
14. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
1. A disc retainer and slotted plate mounting for a snap disc thermostat switch having a pair of nonconductive mating body sections and internal spaced electric terminals, said retainer comprising a shaped sheet metal body having:
2. an upstanding tab portion, and
3. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
4. A disc retainer and slotted plate mounting in accordance with claim 1 which also includes:
5. resilient finger means partially severed from and raised out of the plane of said planar body portion for urging a slotted plate away from said planar body portion and into contact with said free distal extremity.
6. A disc retainer and slotted plate mounting in accordance with claim 1 wherein the slotted plate mounting means includes a pair of upstanding tab portions each having resilient detent portions.
7. A disc retainer and slotted plate mounting in accordance with claim 1 wherein the rectangular planar body portion includes a centrally located aperture for exposing one surface of said snap disc.
8. A disc retainer and slotted plate mounting in accordance with claim 4 wherein the slotted plate mounting means includes a pair of upstanding tab portions disposed on opposite sides of said aperture, each of said tab portions having resilient detent portions.
9. In a thermostat having an elongated nonconductive body member formed with a lengthwise switch chamber open along one face thereof, first and second terminal units extending lengthwise of said chamber, a single rivet securing each terminal unit in said switch chamber, said terminal units including cooperating switch contacts, one of which is movable between a switch open and a switch closed position, a thermally responsive bimetallic snap disc, a bumper operably coacting between said movable switch contact and said disc to move said movable switch contact between open and closed positions in response to movement of said disc, a nonconductive cover member positioned over said one face of said switch chamber and cooperating with said body member to enclose said terminal units, the improvement which comprises a disc retainer and slotted plate mounting having:
10. an upstanding tab portion, and
11. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
12. In a thermostat having an elongated nonconductive body member formed with a lengthwise switch chamber open along one face thereof and including spaced rivet-receiving recesses extending inwardly from the bottom thereof, first and second terminal units extending lengthwise of said chamber, a single rivet securing each terminal unit in said switch chamber, one end of said rivet being exposed in its respective recess, said terminal units including cooperating switch contacts, one of which is movable between a switch open and a switch closed position, a thermally responsive bimetallic snap disc, a bumper operably coacting between said movable switch contact and said disc to move said movable switch contact between open and closed positions in response to movement of said disc, a nonconductive cover member positioned over said one face of said switch chamber and cooperating with said body member to enclose said terminal units, the improvement which comprises a disc retainer and slotted plate mounting having:
13. an upstanding tab portion, and
14. a resilient detent portion partially severed from and depressed out of the plane of said tab portion having a proximal end integral with said tab portion and a free distal extremity closer to said planar body portion than said proximal extremity.
Description:
BACKGROUND OF THE INVENTION
The present invention relates generally to snap disc operated thermostatic switches, and more particularly to a novel and improved disc retainer and slotted plate mounting structure which may be manufactured at relatively low cost and obviate a problem which a closely related prior art structure encounters.
PRIOR ART
Various types of snap disc operated thermostatic switches are well known. Examples of such thermostats are illustrated in U.S. Pat. Nos. 3,081,388, 3,219,783, and 3,322,920. Particular attention is directed to U.S. Pat. No. 3,537,052 which shows a snap disc thermostatic switch of the type which is improved by the present invention in the disc retainer and slotted plate mounting structure.
With the advent of modern space heating devices, and particularly installations in dwellings and office buildings which depend upon electric heating elements mounted in or near the baseboard, it has become important to sense extraordinary temperatures in such devices at intervals between the extremities thereof. To this end, simple snap disc-operated thermostatic switch structures constructed in a manner such as those illustrated in the aforementioned U.S. patent specifications and drawings having axial lead members and connected in series have been utilized for this purpose. Thus, when the temperature at a given region in an elongated electrical floorboard heating installation, for example, exceeds a predetermined temperature, a normally closed thermally responsive snap disc thermostatic switch may be operated by the local high temperature to open the circuit and thus shut down the heating element.
The present invention provides a simpler structure less costly to install. In certain embodiments, means are provided to prevent rattling of the attached thermostat units due to induced vibrations which frequently occur in buildings, for example, not only from external sources, but also from the application of an alternating current source to provide heat.
In still more specific embodiments of the present invention, the relative construction of the body members enclosing the switch chamber and the disc-retaining and slotted plate mounting structure is such as to provide ready external access to electrical terminals for checking the circuit to make sure that all members of a given string of series-connected thermostats are providing a complete circuit. The present invention is especially useful in conjunction with structures such as shown in U.S. Pat. No. 3,537,052, the disclosure of which is incorporated herein by reference thereto. The present invention obviates the necessity for a separate clip 17c of such patent which provides means for mounting the thermostatically operated switches onto a surface.
BRIEF STATEMENT OF THE INVENTION
Briefly stated, the present invention is in a thermostatic switch structure which is characterized by a disc retainer and slotted plate mounting for a snap disc thermostat switch having a pair of nonconductive mating body sections and internal spaced electric terminals, the retainer comprising a shaped sheet metal body having a generally rectangular planar body portion for disposition in disc-retaining relation over a thermally responsive snap disc carried by one of the mating body sections, a pair of parallel orthogonally bent body-engaging side members disposed on parallel marginal edges of the planar body portion and including bendable tab portions for grasping and holding the body sections in mated relation.
The slotted plate mounting means extend out of the plane of the planar body portion in a direction opposite to the side members and have an upstanding tab portion and a resilient detent portion partially severed from and depressed out of the plane of the tab portion. The detent portion has a proximal end integral with the tab portion and a free distal extremity closer to the planar body portion than the proximal extremity. In a more specific embodiment, resilient finger means partially severed from and raised out of the plane of the planar body portion are provided for urging a slotted plate away from the planar body portion and into contact with the free distal extremities of the detent portion or portions as the case may be. This latter structure serves to minimize rattling by confining a slotted plate between the ends of the resilient fingers and the free extremities of the detent portions.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be better understood by having reference to the annexed drawings wherein:
FIG. 1 shows on an enlarged scale a plan view of a thermostatically operated switch structure in accordance with the present invention and having a cover body element removed illustrating the structural arrangement of the switch mechanism.
FIG. 2 is a cross-sectional view of the structure shown in FIG. 1 as it appears in the plane indicated by the line 2--2 of FIG. 1 with the exception that the nonconducting body cover plate has been illustrated in position as the device is finally assembled. FIG. 2 also shows the manner in which electrical contact access to one of the terminals is provided.
FIG. 3 is a plan view of a disc retainer and slotted plate mounting in accordance with the present invention.
FIG. 4 is a cross-sectional view of the disc retainer shown in FIG. 3 as it appears in the plane indicated by the line 4--4 of FIG. 3.
FIG. 5 is an end view of the disc retainer shown in FIG. 3.
FIG. 6 is a fragmentary plan view of a slotted plate containing a pair of spaced mounting slots adapted for coaction with the slotted plate mounting means of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
With the exception of the structure and configuration of the disc-retaining and slotted plate mounting device of the present invention, a preferred and specific environment of the present invention corresponds in structure to that shown in FIGS. 3 - 6 inclusive of the aforementioned U.S. Pat. No. 3,537,052. For purposes of completeness and convenience, the description of FIGS. 1 and 2 of the present drawings will be substantially as and utilize for the most part the same numbering as in FIGS. 3 and 6 of U.S. Pat. No. 3,537,052.
Referring to FIGS. 1 and 2 of the drawings hereof, there is provided a main body member 16 and a cover member 17 which are molded of nonconducting material, e.g., plastic, for mating coaction to provide a switch chamber 20 in which the switch elements are located. Mounted within the switch chamber 20 are first and second terminal assemblies or units 22 and 23. The terminal assembly 22 includes the terminal member 24 which is clinched at 26 onto the end of a lead wire 27 to provide an electrical connection therewith. One end of the terminal member 24 is provided with an insulating gripping portion 25 which grips the insulation of the lead wire 27 adjacent to its end. The other end of the terminal member 24 is a flat mounting section 30 positioned to overlie one end of a mobile contact support member 28. The mobile support member 28 is formed of spring material and is provided with stiffening ribs 29 intermediate its ends. A mobile contact 31 is provided on the free end of the contact support 28.
The mobile contact support member 28 may be welded to the terminal member 24 at its proximal extremity. If desired, however, the mobile contact support 28 and the terminal member 22 do not have to be permanently connected so long as a sufficiently good electrical connection is provided along the interface therebetween, for example by silver plating.
A single rivet 41 projects through an opening 42 in the body 16 and the central portion of the terminal assembly 23 to hold the terminal assembly in position against a mounting surface 43 formed in the body 16.
The switch is operated by a bimetallic snap disc 46 which snaps to the second of its two positions of stability when a predetermined elevated temperature is reached. The snap disc 46 is radially located by a shoulder in the body 16 as shown in the aforementioned U.S. Pat. No. 3,537,052. Extending between the disc 46 and the mobile contact support member 28 is an insulating bumper 51 guided in a passage 52 in the body 16. When the disc is in its cool or normal position, the switch is closed, and when the disc snaps through to its high temperature position of stability, the bumper 51 is caused to move up against the support arm 28 to cause the switch to open.
The body member 16 is nonconducting and preferably formed with an upstanding flange 56 which extends up into and mates with a downwardly extending flange 57 on the cover member 17 to provide lateral positioning of the two body members and to provide a path of substantial length between the electrically charged switch element and the exterior of the body. The lower edge of flange 57 seats against a surface 58 on the member 16 to cooperate with the locking tabs hereinafter more particularly described on the disc retainer 18.
The body assembly in cooperation with the disc retainer provides a complete enclosure for the functioning elements of the thermostat so dirt cannot enter the thermostat to cause malfunction. Further, the structure is arranged so that the terminals are aligned with and in substantially the same plane as the switch elements. With this structure, tension loads applied to the lead wires do not cause any lateral deformation of the contact supporting members. Consequently, the lead wires can be subjected to high tension loads without causing any material change in the calibration of the thermostat. Also, with this structure it is possible to make the thermostat so that its width is substantially equal to the diameter of the disc and its thickness is less than its width. Consequently, it can be quite small so that it can be used in confined locations.
FIGS. 3, 4, and 5 show an improved form of disc retainer and slotted plate mounting means in accordance with the present invention. The disc retainer is generally indicated by the number 18 for consistency with the prior U.S. Pat. No. 3,537,052. The improved disc retainer of the present invention is provided with a generally rectangular planar body portion 70 adapted for disc position in disc-retaining relation over the thermally responsive snap disc 46. In the preferred embodiment illustrated, there is provided an aperture 72 of smaller diameter than the diameter of the disc 46. An annular rim 74 is provided and holds the disc 46 securely in position without, however, interfering with its ability to move between its stable conditions in response to temperature change.
The planar body portion 70 is provided with parallel orthogonally bent body-engaging side members 76 and 78 disposed on the parallel marginal edges 80 and 82. Each of the side members 76 and 78 is provided with bendable tab portions for engaging and holding the body sections 16 and 17 in mated relation. Thus, side member 76 (and its corresponding side member 78) is, in a preferred embodiment, provided with first and second bendable tab portions 84 and 86 which are sufficiently dimensioned to extend past the height of body portion 16 and engage the cover portion 17 in suitable recesses therein provided as fully disclosed in U.S. Pat. No. 3,537,052. Also provided are bendable third and fourth tab portions 53 and 53' (best illustrated in FIG. 1) which are bent over mating shoulders 54 and 54' in the body member 16. These latter tabs securely connect the disc retainer to the main body 16 and the longer bendable tabs 84 and 86 separately secure the cover member 17 to the main body member 16.
Up to this point, the structure of the disc retainer member 18 is quite similar to the disc retainer member shown in U.S. Pat. No. 3,537,052.
In accordance with the present invention, however, the disc retainer member 18 is further modified to provide slotted plate mounting means integral therewith and extending out of the plane of the planar body portion 70 and in a direction which is opposite to the side members 76 and 78. The slotted plate mounting means include an upstanding tab portion such as upstanding tab portions 88 and 90, each of which includes resilient detent portions 92 and 94, respectively. The detent portions 92 and 94 are partially severed from and depressed out of the planes of the tab portions 88 and 90, respectively, and have their proximal ends 96 and 98, respectively, integral with the tab portion. The free distal extremities 100 and 102 of the detents 92 and 94, respectively, are preferably although not essentially directed toward each other, i.e., inwardly of the disc retainer body 18, and are closer to the planar body portion 70 than the proximal extremities 96 and 98.
In order to minimize noise which may occur with loose mountings, it is desirable to provide resilient finger means partially severed from and raised out of the plane of the planar body 70. To this end, therefore, there are provided as best shown in FIG. 4 resilient fingers 104 and 106. As shown in FIG. 4, these are bent downwardly out of the plane of the planar body 70 with the free extremities thereof 108 and 110, respectively, lying in a plane which approaches the plane of the free extremities 100 and 102 of the detents 92 and 94, respectively. Desirably, the distance between the plane including the free extremities 108 and 110 of the resilient fingers 104 and 106, respectively, and the plane including the free extremities 100 and 102 of the detents 92 and 94 is less than the thickness of the slotted plate to which the thermostatically responsive switch device is to be attached. Under such circumstances, the resilient fingers 104 and 106 are placed under compressive stress of sufficient magnitude to firmly mount the thermostat on the slotted plate and minimize rattling.
FIG. 6 shows a portion of a slotted plate including slots 112 and 114 which are adapted and located, respectively, to coact with tabs 88 and 90. The extent of deflection of the detent portions 92 and 94 at their distal extremities 100 and 102 is sufficient that resistance to free movement thereof through the slots 112 and 114 is encountered, and when the slotted plate and the thermostat body are seated one relative to the other, the distal extremities 100 and 102 are seated on the surface 116 due to the resilience of the detent portions 92 and 94. The distal extremities 108 and 110 of the finger portions 104 and 106 rest against the opposite side of the plate 111 and urge the surface 116 into firm contact with the detents 92 and 94. Rattling is thereby minimized.
In forming the tabs 88 and 90 by bending them out of the plane of the planar body portion 70, in accordance with FIGS. 3 - 5, it will be observed that the button head 118 of rivet 41 in rivet-receiving recess 119 is exposed. This will also occur with rivet 34 when the body 16 is formed as shown in FIG. 4 of U.S. Pat. No. 3,537,052. This arrangement enables easy testing of the circuit and the thermostat after assembly to determine whether in manufacture the switch is not properly operative after assembly.
The present invention constitutes an improvement over the prior structure because the advantages of the prior structure such as shown in U.S. Pat. No. 3,537,052 are retained and, additionally, the disc retainer and mounting device provides the additional function of enabling ready mounting to a slotted plate which eliminates at least one part and further reduces manufacturing and installation costs. Moreover, the device enables simple testing of the circuit prior to installation but after the thermostat switch structure has been assembled.
Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed.
The present invention relates generally to snap disc operated thermostatic switches, and more particularly to a novel and improved disc retainer and slotted plate mounting structure which may be manufactured at relatively low cost and obviate a problem which a closely related prior art structure encounters.
PRIOR ART
Various types of snap disc operated thermostatic switches are well known. Examples of such thermostats are illustrated in U.S. Pat. Nos. 3,081,388, 3,219,783, and 3,322,920. Particular attention is directed to U.S. Pat. No. 3,537,052 which shows a snap disc thermostatic switch of the type which is improved by the present invention in the disc retainer and slotted plate mounting structure.
With the advent of modern space heating devices, and particularly installations in dwellings and office buildings which depend upon electric heating elements mounted in or near the baseboard, it has become important to sense extraordinary temperatures in such devices at intervals between the extremities thereof. To this end, simple snap disc-operated thermostatic switch structures constructed in a manner such as those illustrated in the aforementioned U.S. patent specifications and drawings having axial lead members and connected in series have been utilized for this purpose. Thus, when the temperature at a given region in an elongated electrical floorboard heating installation, for example, exceeds a predetermined temperature, a normally closed thermally responsive snap disc thermostatic switch may be operated by the local high temperature to open the circuit and thus shut down the heating element.
The present invention provides a simpler structure less costly to install. In certain embodiments, means are provided to prevent rattling of the attached thermostat units due to induced vibrations which frequently occur in buildings, for example, not only from external sources, but also from the application of an alternating current source to provide heat.
In still more specific embodiments of the present invention, the relative construction of the body members enclosing the switch chamber and the disc-retaining and slotted plate mounting structure is such as to provide ready external access to electrical terminals for checking the circuit to make sure that all members of a given string of series-connected thermostats are providing a complete circuit. The present invention is especially useful in conjunction with structures such as shown in U.S. Pat. No. 3,537,052, the disclosure of which is incorporated herein by reference thereto. The present invention obviates the necessity for a separate clip 17c of such patent which provides means for mounting the thermostatically operated switches onto a surface.
BRIEF STATEMENT OF THE INVENTION
Briefly stated, the present invention is in a thermostatic switch structure which is characterized by a disc retainer and slotted plate mounting for a snap disc thermostat switch having a pair of nonconductive mating body sections and internal spaced electric terminals, the retainer comprising a shaped sheet metal body having a generally rectangular planar body portion for disposition in disc-retaining relation over a thermally responsive snap disc carried by one of the mating body sections, a pair of parallel orthogonally bent body-engaging side members disposed on parallel marginal edges of the planar body portion and including bendable tab portions for grasping and holding the body sections in mated relation.
The slotted plate mounting means extend out of the plane of the planar body portion in a direction opposite to the side members and have an upstanding tab portion and a resilient detent portion partially severed from and depressed out of the plane of the tab portion. The detent portion has a proximal end integral with the tab portion and a free distal extremity closer to the planar body portion than the proximal extremity. In a more specific embodiment, resilient finger means partially severed from and raised out of the plane of the planar body portion are provided for urging a slotted plate away from the planar body portion and into contact with the free distal extremities of the detent portion or portions as the case may be. This latter structure serves to minimize rattling by confining a slotted plate between the ends of the resilient fingers and the free extremities of the detent portions.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be better understood by having reference to the annexed drawings wherein:
FIG. 1 shows on an enlarged scale a plan view of a thermostatically operated switch structure in accordance with the present invention and having a cover body element removed illustrating the structural arrangement of the switch mechanism.
FIG. 2 is a cross-sectional view of the structure shown in FIG. 1 as it appears in the plane indicated by the line 2--2 of FIG. 1 with the exception that the nonconducting body cover plate has been illustrated in position as the device is finally assembled. FIG. 2 also shows the manner in which electrical contact access to one of the terminals is provided.
FIG. 3 is a plan view of a disc retainer and slotted plate mounting in accordance with the present invention.
FIG. 4 is a cross-sectional view of the disc retainer shown in FIG. 3 as it appears in the plane indicated by the line 4--4 of FIG. 3.
FIG. 5 is an end view of the disc retainer shown in FIG. 3.
FIG. 6 is a fragmentary plan view of a slotted plate containing a pair of spaced mounting slots adapted for coaction with the slotted plate mounting means of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
With the exception of the structure and configuration of the disc-retaining and slotted plate mounting device of the present invention, a preferred and specific environment of the present invention corresponds in structure to that shown in FIGS. 3 - 6 inclusive of the aforementioned U.S. Pat. No. 3,537,052. For purposes of completeness and convenience, the description of FIGS. 1 and 2 of the present drawings will be substantially as and utilize for the most part the same numbering as in FIGS. 3 and 6 of U.S. Pat. No. 3,537,052.
Referring to FIGS. 1 and 2 of the drawings hereof, there is provided a main body member 16 and a cover member 17 which are molded of nonconducting material, e.g., plastic, for mating coaction to provide a switch chamber 20 in which the switch elements are located. Mounted within the switch chamber 20 are first and second terminal assemblies or units 22 and 23. The terminal assembly 22 includes the terminal member 24 which is clinched at 26 onto the end of a lead wire 27 to provide an electrical connection therewith. One end of the terminal member 24 is provided with an insulating gripping portion 25 which grips the insulation of the lead wire 27 adjacent to its end. The other end of the terminal member 24 is a flat mounting section 30 positioned to overlie one end of a mobile contact support member 28. The mobile support member 28 is formed of spring material and is provided with stiffening ribs 29 intermediate its ends. A mobile contact 31 is provided on the free end of the contact support 28.
The mobile contact support member 28 may be welded to the terminal member 24 at its proximal extremity. If desired, however, the mobile contact support 28 and the terminal member 22 do not have to be permanently connected so long as a sufficiently good electrical connection is provided along the interface therebetween, for example by silver plating.
A single rivet 41 projects through an opening 42 in the body 16 and the central portion of the terminal assembly 23 to hold the terminal assembly in position against a mounting surface 43 formed in the body 16.
The switch is operated by a bimetallic snap disc 46 which snaps to the second of its two positions of stability when a predetermined elevated temperature is reached. The snap disc 46 is radially located by a shoulder in the body 16 as shown in the aforementioned U.S. Pat. No. 3,537,052. Extending between the disc 46 and the mobile contact support member 28 is an insulating bumper 51 guided in a passage 52 in the body 16. When the disc is in its cool or normal position, the switch is closed, and when the disc snaps through to its high temperature position of stability, the bumper 51 is caused to move up against the support arm 28 to cause the switch to open.
The body member 16 is nonconducting and preferably formed with an upstanding flange 56 which extends up into and mates with a downwardly extending flange 57 on the cover member 17 to provide lateral positioning of the two body members and to provide a path of substantial length between the electrically charged switch element and the exterior of the body. The lower edge of flange 57 seats against a surface 58 on the member 16 to cooperate with the locking tabs hereinafter more particularly described on the disc retainer 18.
The body assembly in cooperation with the disc retainer provides a complete enclosure for the functioning elements of the thermostat so dirt cannot enter the thermostat to cause malfunction. Further, the structure is arranged so that the terminals are aligned with and in substantially the same plane as the switch elements. With this structure, tension loads applied to the lead wires do not cause any lateral deformation of the contact supporting members. Consequently, the lead wires can be subjected to high tension loads without causing any material change in the calibration of the thermostat. Also, with this structure it is possible to make the thermostat so that its width is substantially equal to the diameter of the disc and its thickness is less than its width. Consequently, it can be quite small so that it can be used in confined locations.
FIGS. 3, 4, and 5 show an improved form of disc retainer and slotted plate mounting means in accordance with the present invention. The disc retainer is generally indicated by the number 18 for consistency with the prior U.S. Pat. No. 3,537,052. The improved disc retainer of the present invention is provided with a generally rectangular planar body portion 70 adapted for disc position in disc-retaining relation over the thermally responsive snap disc 46. In the preferred embodiment illustrated, there is provided an aperture 72 of smaller diameter than the diameter of the disc 46. An annular rim 74 is provided and holds the disc 46 securely in position without, however, interfering with its ability to move between its stable conditions in response to temperature change.
The planar body portion 70 is provided with parallel orthogonally bent body-engaging side members 76 and 78 disposed on the parallel marginal edges 80 and 82. Each of the side members 76 and 78 is provided with bendable tab portions for engaging and holding the body sections 16 and 17 in mated relation. Thus, side member 76 (and its corresponding side member 78) is, in a preferred embodiment, provided with first and second bendable tab portions 84 and 86 which are sufficiently dimensioned to extend past the height of body portion 16 and engage the cover portion 17 in suitable recesses therein provided as fully disclosed in U.S. Pat. No. 3,537,052. Also provided are bendable third and fourth tab portions 53 and 53' (best illustrated in FIG. 1) which are bent over mating shoulders 54 and 54' in the body member 16. These latter tabs securely connect the disc retainer to the main body 16 and the longer bendable tabs 84 and 86 separately secure the cover member 17 to the main body member 16.
Up to this point, the structure of the disc retainer member 18 is quite similar to the disc retainer member shown in U.S. Pat. No. 3,537,052.
In accordance with the present invention, however, the disc retainer member 18 is further modified to provide slotted plate mounting means integral therewith and extending out of the plane of the planar body portion 70 and in a direction which is opposite to the side members 76 and 78. The slotted plate mounting means include an upstanding tab portion such as upstanding tab portions 88 and 90, each of which includes resilient detent portions 92 and 94, respectively. The detent portions 92 and 94 are partially severed from and depressed out of the planes of the tab portions 88 and 90, respectively, and have their proximal ends 96 and 98, respectively, integral with the tab portion. The free distal extremities 100 and 102 of the detents 92 and 94, respectively, are preferably although not essentially directed toward each other, i.e., inwardly of the disc retainer body 18, and are closer to the planar body portion 70 than the proximal extremities 96 and 98.
In order to minimize noise which may occur with loose mountings, it is desirable to provide resilient finger means partially severed from and raised out of the plane of the planar body 70. To this end, therefore, there are provided as best shown in FIG. 4 resilient fingers 104 and 106. As shown in FIG. 4, these are bent downwardly out of the plane of the planar body 70 with the free extremities thereof 108 and 110, respectively, lying in a plane which approaches the plane of the free extremities 100 and 102 of the detents 92 and 94, respectively. Desirably, the distance between the plane including the free extremities 108 and 110 of the resilient fingers 104 and 106, respectively, and the plane including the free extremities 100 and 102 of the detents 92 and 94 is less than the thickness of the slotted plate to which the thermostatically responsive switch device is to be attached. Under such circumstances, the resilient fingers 104 and 106 are placed under compressive stress of sufficient magnitude to firmly mount the thermostat on the slotted plate and minimize rattling.
FIG. 6 shows a portion of a slotted plate including slots 112 and 114 which are adapted and located, respectively, to coact with tabs 88 and 90. The extent of deflection of the detent portions 92 and 94 at their distal extremities 100 and 102 is sufficient that resistance to free movement thereof through the slots 112 and 114 is encountered, and when the slotted plate and the thermostat body are seated one relative to the other, the distal extremities 100 and 102 are seated on the surface 116 due to the resilience of the detent portions 92 and 94. The distal extremities 108 and 110 of the finger portions 104 and 106 rest against the opposite side of the plate 111 and urge the surface 116 into firm contact with the detents 92 and 94. Rattling is thereby minimized.
In forming the tabs 88 and 90 by bending them out of the plane of the planar body portion 70, in accordance with FIGS. 3 - 5, it will be observed that the button head 118 of rivet 41 in rivet-receiving recess 119 is exposed. This will also occur with rivet 34 when the body 16 is formed as shown in FIG. 4 of U.S. Pat. No. 3,537,052. This arrangement enables easy testing of the circuit and the thermostat after assembly to determine whether in manufacture the switch is not properly operative after assembly.
The present invention constitutes an improvement over the prior structure because the advantages of the prior structure such as shown in U.S. Pat. No. 3,537,052 are retained and, additionally, the disc retainer and mounting device provides the additional function of enabling ready mounting to a slotted plate which eliminates at least one part and further reduces manufacturing and installation costs. Moreover, the device enables simple testing of the circuit prior to installation but after the thermostat switch structure has been assembled.
Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed.