US2834853A - Snap-acting bimetal device - Google Patents
Snap-acting bimetal device Download PDFInfo
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- US2834853A US2834853A US652500A US65250057A US2834853A US 2834853 A US2834853 A US 2834853A US 652500 A US652500 A US 652500A US 65250057 A US65250057 A US 65250057A US 2834853 A US2834853 A US 2834853A
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- bimetal
- snap
- strip portion
- strip
- blank
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H37/5418—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting using cantilevered bimetallic snap elements
Definitions
- This invention relates to snap-acting devices and more particularly to snap-acting bimetal elements useful in thermostatic switches.
- An object of the invention is to provide a thermostatic device which operates with a positive snap action in both make and break action.
- Another object of this invention is to provide a snapaeting thermostatic switch having a relatively wide gap between the fixed and movable contacts in the open position.
- thermostatic switches having the characteristics mentioned above have employed a fiat bimetal element mounted at one end in a cantilever fashion with its opposite end which carries a contact moving with a snap action between two stable positions.
- a bimetal element is provided with three substantially parallel legs of which the outer two are deformed to arch or bow the center leg in such a manner that the internal stresses developed by the bimetal with temperature change cause the free end of the element to move over a comparatively large distance with a snap action.
- bimetal elements are not adapted for convenient calibration or adjustment of their operating characteristics such as the make and break temperatures. Very small variations in the deformation of the legs result in substantially large variations in the bimetal element operating characteristics and as a result, such bimetal elements have been diflicult to calibrate with operating characteristics within narrow limits or even with operating characteristics uniform from one elemen to the next.
- a further object of the present invention is to provide a new form of snap-acting elements for thermostatic switches which is efficient in operation and which can be economically manufactured with uniformity in calibration.
- Still another object is to provide a snap-acting thermostatic switch in which the stressing means are self-contained and which require no external springs or applied forces to produce a snap action.
- Figure 1 is a plan view of a longitudinally curved bimetal blank.
- Figure 2 is a longitudinal side view of the bimetal blank.
- Figure 3 is a plan view of a snap-acting member formed from the bimetal blank of Figures 1 and 2.
- Figure 4 is a longitudinal side view of the snap-acting member.
- Figure 5 is a plan view of the snap-acting member secured to a support in a switch assembly.
- Figure 6 is a side elevation of Figure 5.
- Figure 7 is a plan view of another form of the snapacting member.
- Figure 8 is a longitudinal side view of the snap-acting member in Figure 7.
- a longitudinally curved bimetal blank 10 having substantially triangular shape with a central aperture or slot 11 which separates the blank 10 into a first strip portion 12 and a. second strip portion 13 integrally joined at their separated ends by a base portion 14.
- the blank 10 is provided with a hole 15 located in the base portion 14.
- the blank 10 is a one piece stamping from a flat sheet of thermostatic bimetal material composed of two thin layers of metal bonded together and having different temperature coeflicients of expansion.
- the high expansion layer is preferably disposed on the lower or contactcarrying side of the blank 10.
- the bimetal blank 10 is provided with a permanent longitudinally curved or bowed form so that the high expansive side of the blank is concave. The radius of curvature will vary with the snap and reset temperature requirements as well as the thickness, hardness, and type of thermostatic bimetal employed.
- Snap action in the bimetal member 16 of Figures 3 and 4 is accomplished by stamping a permanently set small indentation or crimp 17 in the narrow strip portion 13. This indentation draws the ends of the strip portion 13 closer together to produce a tension force in the narrow strip portion 13 and a compression force in the wide strip portion 12. These forces together with that resulting from the longitudinal curvature of the blank 10 stress the bimetal member 16 such that its surface has a non-developable concave-convex form. This non-developable surface form gives the snap-acting member a rigidity which in a switch assembly provides good contact pressure even under conditions of severe vibration.
- the member 16 With strip portions having the correct dimensional proportions, forming, and crimping, the member 16 will move with a snap action when heated to a predetermined temperature. With the application of heat, the greater expansion of the metal on the concave surface of the bimetal member 16 causes it to become convex at a predetermined temperature with a pronounced snap action. When the bimetal cools sutficiently, the member 16 snaps back to its original contour.
- the stressing means are entirely self-contained and no external springs or applied forces are required to produce snap-action.
- Strip portion 12 preferably should be 1.4 to 2.4 times as wide as strip portion 13. No snap action is obtained with bimetal members having width ratios much beyond these limits. It is also preferable that the narrow strip portion be longer than the wider strip portion in order that its length may change at a greater rate than that of the wider strip portion.
- Figures 7 and 8 illustrate a modification of the above bimetal member in which the triangular shape is more pronounced.
- the member 18 is constructed in the same manner as member 16 shown in Figures 3 and 4, and accordingly, its parts have been designated with the same reference numerals. Member 18 differs from member 16 only in its shape which is somewhat less suitable for extremely compact switch assemblies.
- Figures 5 and 6 illustrate the use of the member 16 of Figures 3 and 4 as part of a switch assembly such as nected to terminal 25. Since thesurface of the member 16 id eiirved, the area of contact between the bimetal member 16 and contact 23 is kept to a minimum to avoid any effect on the operating characteristics of the bimetal em -.7
- the amount of longitudinal curvature of the blank 10 and the amount of crimping of the narrow strip portion 13 may be readily varied to control the snap or operating temperature and the reset temperature of the snapacting member 16.
- the final curvature of the member 16 determines the snap temperature and is dependent upon both the longitudinal curvature of the blank 10 and the crimping of the narrow strip portion 13.
- the snap temperature is relatively independent of the longitudinal curvature of the blank it) and varies mainly with changes in the depth ofjcrimping in the narrow strip portion113. Greater depthof crimping in the narrow strip portion 13 results in a higher snap temperature.
- the reset temperature varies substantially with changes in either the longitudinal curvature or the depth of crimping. For any particular amount of crimping, the reset temperature will decrease with a decrease in longitudinal curvature. If the longitudinal curvature of the blank 10 is fixed, the reset temperature will decrease with increase in the depth of the crimp 17 in the narrow strip portion 13. I i i 7 By properly correlating the longitudinal curvature of the blank 10 with the depth of crimping in the narrow strip portion 13, both the snap and reset-temperatures may be readily maintained within narrow limits. Variations in the bimetal thickness, hardness, or characteristics are easily compensated for by suitably adjusting the forming dies for the longitudinal curvature and/or the crimp. Furthermore, no hand adjustment or calibration of the switch assembly employing these snap-acting members is required as the blades are pro-formed with the desired operating characteristics.
- a substantially triangular bimetal member having a base portion and cqnverging sides meeting at an apex portion, said bimetal member having an aperture cxtending longitudinally between said base and apex portions with edges substantially parallel to said converging sides to form a first strip portionon one side of said aperture and a second narrower strip portion (if greater length on the other side of said aper-ture, said stripportions being longitudinally curved convexly from a common plane, and said second strip portion having atransversely extending crimp stressing said bimetal member into' a non-developable form.
- Ir1 thermally responsive device a slotted integral bimetal member having converging first and second strip portions joined b y a base portionat their separated ends, said second strip portion having a generally uniform Width less than that of said first strip portion and having a length greater than that of said first strip portion, said first and second strip portion being deformed to stress s aid bimetal into a concavo-convex non-developable form, one of said strip portions being in tension and the other being in compression to provide for snap action of said bimetal member.
- thermally responsive switch comprising: a supportmernber; a first contact carried by said support member; a slotted integral bimetal member of substantially triangular shape having a base portion and converging Sides meeting at an apex portion, said bimetal member having an aperture extending longitudinally between said base and apex safeties edges substantially parallel to said converging sides to form a first strip portion on one side of said aperture and a second narrower strip portion of greater length on the other side of said aperture, said strip portions being longitudinally curved convexly from a common plane, said second strip portion having a transversely extending crimp stressing said bimetal member into a non developable form, said bimetal member being supported at oneend thereof by said sup port member such that one end of said base portion is freely flexible in the presence of thermal stresses for movement relative to the other end of said base portion; and a second contact actuated by said bimetal member co-operating with said first contact.
- an elongated bimetal member having a single longitudinally extendingaperture of substantially triangular shape separating said member into a first and a second non-parallel strip portions integrally joined together at their ends and having generally uniform widths, said first strip portion being wider and shorter than said second strip portion, said strip portions being longitudinally curved convcxly from a common plane, and said second strip portion being further deformed to stress said member into a concaveconvex non-developable form.
- a sub stantially triangular bimetal member having a base portion and converging sides meeting at an apex portion
- sa id bimetal member having an aperture extending longitudinally between saidbase and apex portions with edges substantially parallel to said converging sides to form a first strip portion on one side of said aperture and a second narrower strip portion of greater length on the other side of said aperture, said strip portions being initially longitudinally curved convexly from a common plane, said second strip portion being additionally provided with a transversely extending crimp stressing said bimetal member into a non-develop able form, and the base portion adjacent one strip portion being freely flexible in the presence of thermal stresses for movement relative to the base portion adjacent the other of said strip portions 7.
- a thermally responsive switch comprising: a support member; a fixed contact'carried by said support member; a bimetal member of substantially triangular shape mounted upon said support member; a movable contact member carried by said bimetal member for engagement with said fixed contact; said bimetal member comprising first and second strip portions joined by a base portion at their separated ends; said second strip portion having a generally uniform width less than that of said first strip portion and having a length greater than that of said first strip portion; said first and second strip portions being initially formed with a longitudinally convex curvature away from a common plane; said second strip portion being additionally formed with a transversely extending crimp buckling said bimetal member in a direction at anangle to said longitudinal convex curvature to stress said bimetal member into a non-developable form; and means attaching said bimetal member to said support member such that the base portion adjacent one strip portion is freely flexible in the presence of thermal stresses for movement relative to the base portion adjacent the other of said strip portions.
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Thermally Actuated Switches (AREA)
Description
y 13, 58 s. R. HOOD 2,834,853
' SNAP-ACTING BIMETAL DEVIICE Filed April 12, 1957 "IT 5-; l
UnitedStates Patent Q SNAP-ACTING BIMETAL DEVICE Stanley R. Hood, Birmingham, Mich., assignor to Essex Wire Corporation Application April 12, 1957, Serial No. 652,500
7 Claims. (Cl. 200-138) This invention relates to snap-acting devices and more particularly to snap-acting bimetal elements useful in thermostatic switches.
An object of the invention is to provide a thermostatic device which operates with a positive snap action in both make and break action.
Another object of this invention is to provide a snapaeting thermostatic switch having a relatively wide gap between the fixed and movable contacts in the open position.
Known forms of thermostatic switches having the characteristics mentioned above have employed a fiat bimetal element mounted at one end in a cantilever fashion with its opposite end which carries a contact moving with a snap action between two stable positions. Generally such a bimetal element is provided with three substantially parallel legs of which the outer two are deformed to arch or bow the center leg in such a manner that the internal stresses developed by the bimetal with temperature change cause the free end of the element to move over a comparatively large distance with a snap action.
These three-legged type of bimetal elements are not adapted for convenient calibration or adjustment of their operating characteristics such as the make and break temperatures. Very small variations in the deformation of the legs result in substantially large variations in the bimetal element operating characteristics and as a result, such bimetal elements have been diflicult to calibrate with operating characteristics within narrow limits or even with operating characteristics uniform from one elemen to the next.
Accordingly a further object of the present invention is to provide a new form of snap-acting elements for thermostatic switches which is efficient in operation and which can be economically manufactured with uniformity in calibration.
Still another object is to provide a snap-acting thermostatic switch in which the stressing means are self-contained and which require no external springs or applied forces to produce a snap action.
Other objects and advantages of the invention will be apparent from the following description and the accompanying drawing, in which:
Figure 1 is a plan view of a longitudinally curved bimetal blank.
Figure 2 is a longitudinal side view of the bimetal blank.
Figure 3 is a plan view of a snap-acting member formed from the bimetal blank of Figures 1 and 2.
Figure 4 is a longitudinal side view of the snap-acting member.
Figure 5 is a plan view of the snap-acting member secured to a support in a switch assembly.
Figure 6 is a side elevation of Figure 5.
Figure 7 is a plan view of another form of the snapacting member.
Figure 8 is a longitudinal side view of the snap-acting member in Figure 7.
Referring to Figures 1 and 2, there is shown a longitudinally curved bimetal blank 10 having substantially triangular shape with a central aperture or slot 11 which separates the blank 10 into a first strip portion 12 and a. second strip portion 13 integrally joined at their separated ends by a base portion 14. For mounting the snapacting member to be formed from the blank in a switch assembly, the blank 10 is provided with a hole 15 located in the base portion 14.
The blank 10 is a one piece stamping from a flat sheet of thermostatic bimetal material composed of two thin layers of metal bonded together and having different temperature coeflicients of expansion. For use in the switch assembly of Figures 5 and 6, the high expansion layer is preferably disposed on the lower or contactcarrying side of the blank 10. The bimetal blank 10 is provided with a permanent longitudinally curved or bowed form so that the high expansive side of the blank is concave. The radius of curvature will vary with the snap and reset temperature requirements as well as the thickness, hardness, and type of thermostatic bimetal employed.
Snap action in the bimetal member 16 of Figures 3 and 4 is accomplished by stamping a permanently set small indentation or crimp 17 in the narrow strip portion 13. This indentation draws the ends of the strip portion 13 closer together to produce a tension force in the narrow strip portion 13 and a compression force in the wide strip portion 12. These forces together with that resulting from the longitudinal curvature of the blank 10 stress the bimetal member 16 such that its surface has a non-developable concave-convex form. This non-developable surface form gives the snap-acting member a rigidity which in a switch assembly provides good contact pressure even under conditions of severe vibration.
With strip portions having the correct dimensional proportions, forming, and crimping, the member 16 will move with a snap action when heated to a predetermined temperature. With the application of heat, the greater expansion of the metal on the concave surface of the bimetal member 16 causes it to become convex at a predetermined temperature with a pronounced snap action. When the bimetal cools sutficiently, the member 16 snaps back to its original contour. The stressing means are entirely self-contained and no external springs or applied forces are required to produce snap-action.
It is important that the two strip portions 12 and 13 have the correct proportions. Strip portion 12 preferably should be 1.4 to 2.4 times as wide as strip portion 13. No snap action is obtained with bimetal members having width ratios much beyond these limits. It is also preferable that the narrow strip portion be longer than the wider strip portion in order that its length may change at a greater rate than that of the wider strip portion.
Figures 7 and 8 illustrate a modification of the above bimetal member in which the triangular shape is more pronounced. The member 18 is constructed in the same manner as member 16 shown in Figures 3 and 4, and accordingly, its parts have been designated with the same reference numerals. Member 18 differs from member 16 only in its shape which is somewhat less suitable for extremely compact switch assemblies.
Figures 5 and 6 illustrate the use of the member 16 of Figures 3 and 4 as part of a switch assembly such as nected to terminal 25. Since thesurface of the member 16 id eiirved, the area of contact between the bimetal member 16 and contact 23 is kept to a minimum to avoid any effect on the operating characteristics of the bimetal em -.7
amount of longitudinal curvature of the blank 10 and the amount of crimping of the narrow strip portion 13 may be readily varied to control the snap or operating temperature and the reset temperature of the snapacting member 16. The final curvature of the member 16 determines the snap temperature and is dependent upon both the longitudinal curvature of the blank 10 and the crimping of the narrow strip portion 13. Actually, the snap temperature is relatively independent of the longitudinal curvature of the blank it) and varies mainly with changes in the depth ofjcrimping in the narrow strip portion113. Greater depthof crimping in the narrow strip portion 13 results in a higher snap temperature.
The reset temperature varies substantially with changes in either the longitudinal curvature or the depth of crimping. For any particular amount of crimping, the reset temperature will decrease with a decrease in longitudinal curvature. If the longitudinal curvature of the blank 10 is fixed, the reset temperature will decrease with increase in the depth of the crimp 17 in the narrow strip portion 13. I i i 7 By properly correlating the longitudinal curvature of the blank 10 with the depth of crimping in the narrow strip portion 13, both the snap and reset-temperatures may be readily maintained within narrow limits. Variations in the bimetal thickness, hardness, or characteristics are easily compensated for by suitably adjusting the forming dies for the longitudinal curvature and/or the crimp. Furthermore, no hand adjustment or calibration of the switch assembly employing these snap-acting members is required as the blades are pro-formed with the desired operating characteristics.
While preferred embodiments of the invention have been illustrated, it should be understood that other modifications may be made without departing from the spirit and the scope of the invention as defined in the claims which follows.
I claim as my invention:
1. In a thermally responsive snap action device, a substantially triangular bimetal member having a base portion and cqnverging sides meeting at an apex portion, said bimetal member having an aperture cxtending longitudinally between said base and apex portions with edges substantially parallel to said converging sides to form a first strip portionon one side of said aperture and a second narrower strip portion (if greater length on the other side of said aper-ture, said stripportions being longitudinally curved convexly from a common plane, and said second strip portion having atransversely extending crimp stressing said bimetal member into' a non-developable form.
2. Ir1 thermally responsive device, a slotted integral bimetal member having converging first and second strip portions joined b y a base portionat their separated ends, said second strip portion having a generally uniform Width less than that of said first strip portion and having a length greater than that of said first strip portion, said first and second strip portion being deformed to stress s aid bimetal into a concavo-convex non-developable form, one of said strip portions being in tension and the other being in compression to provide for snap action of said bimetal member. I v
I 3. The bimetal member defined claim 2 and further eharaeterized by said first leg being 1.4 to 2.4 times as wide as sa d sesame leg.
4, thermally responsive switch comprising: a supportmernber; a first contact carried by said support member; a slotted integral bimetal member of substantially triangular shape having a base portion and converging Sides meeting at an apex portion, said bimetal member having an aperture extending longitudinally between said base and apex safeties edges substantially parallel to said converging sides to form a first strip portion on one side of said aperture and a second narrower strip portion of greater length on the other side of said aperture, said strip portions being longitudinally curved convexly from a common plane, said second strip portion having a transversely extending crimp stressing said bimetal member into a non developable form, said bimetal member being supported at oneend thereof by said sup port member such that one end of said base portion is freely flexible in the presence of thermal stresses for movement relative to the other end of said base portion; and a second contact actuated by said bimetal member co-operating with said first contact.
5. in a thermally responsive snap-action device, an elongated bimetal member having a single longitudinally extendingaperture of substantially triangular shape separating said member into a first and a second non-parallel strip portions integrally joined together at their ends and having generally uniform widths, said first strip portion being wider and shorter than said second strip portion, said strip portions being longitudinally curved convcxly from a common plane, and said second strip portion being further deformed to stress said member into a concaveconvex non-developable form.
6. In a thermally responsive snap action device, a sub stantially triangular bimetal member having a base portion and converging sides meeting at an apex portion, sa id bimetal member having an aperture extending longitudinally between saidbase and apex portions with edges substantially parallel to said converging sides to form a first strip portion on one side of said aperture and a second narrower strip portion of greater length on the other side of said aperture, said strip portions being initially longitudinally curved convexly from a common plane, said second strip portion being additionally provided with a transversely extending crimp stressing said bimetal member into a non-develop able form, and the base portion adjacent one strip portion being freely flexible in the presence of thermal stresses for movement relative to the base portion adjacent the other of said strip portions 7. A thermally responsive switch comprising: a support member; a fixed contact'carried by said support member; a bimetal member of substantially triangular shape mounted upon said support member; a movable contact member carried by said bimetal member for engagement with said fixed contact; said bimetal member comprising first and second strip portions joined by a base portion at their separated ends; said second strip portion having a generally uniform width less than that of said first strip portion and having a length greater than that of said first strip portion; said first and second strip portions being initially formed with a longitudinally convex curvature away from a common plane; said second strip portion being additionally formed with a transversely extending crimp buckling said bimetal member in a direction at anangle to said longitudinal convex curvature to stress said bimetal member into a non-developable form; and means attaching said bimetal member to said support member such that the base portion adjacent one strip portion is freely flexible in the presence of thermal stresses for movement relative to the base portion adjacent the other of said strip portions.
References Cited in the file of this patent UNITED STATES PATENTS 2,171,895 Sardeson Sept. 5, 1939 2,363,280 Arnold Nov. 21, 1944 2 ,425,717 Bean Aug 19', 1 947 2,432,488 Peacock et al Dec. 9, 1947
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US652500A US2834853A (en) | 1957-04-12 | 1957-04-12 | Snap-acting bimetal device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US652500A US2834853A (en) | 1957-04-12 | 1957-04-12 | Snap-acting bimetal device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2834853A true US2834853A (en) | 1958-05-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US652500A Expired - Lifetime US2834853A (en) | 1957-04-12 | 1957-04-12 | Snap-acting bimetal device |
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| Country | Link |
|---|---|
| US (1) | US2834853A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2879355A (en) * | 1957-06-06 | 1959-03-24 | Hoda Corp | Snap action device |
| US3057981A (en) * | 1961-03-23 | 1962-10-09 | Charles V Todoran | Electric socket adapter with fuse plug |
| US3110788A (en) * | 1959-11-17 | 1963-11-12 | Signal Stat Corp | Automatic re-set thermostatic circuit breaker |
| US3112384A (en) * | 1959-07-29 | 1963-11-26 | Texas Instruments Inc | Thermal relays |
| US3256406A (en) * | 1963-04-25 | 1966-06-14 | Ideal Corp | Single-curved vane-type thermally actuated switch |
| US3275773A (en) * | 1964-04-09 | 1966-09-27 | Grover Products Corp | Over-center snap switch |
| EP0376660A2 (en) * | 1988-12-28 | 1990-07-04 | Otter Controls Limited | Improvements relating to thermal switches |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2171895A (en) * | 1937-02-23 | 1939-09-05 | Mcgraw Electric Co | Compensated bimetal thermostat |
| US2363280A (en) * | 1941-05-14 | 1944-11-21 | Westinghouse Electric & Mfg Co | Circuit controller |
| US2425717A (en) * | 1942-06-25 | 1947-08-19 | F A Smith Mfg Company | Thermostatic switch assembly |
| US2432488A (en) * | 1944-03-27 | 1947-12-09 | Sylvania Electric Prod | Glow starter for electric discharge devices |
-
1957
- 1957-04-12 US US652500A patent/US2834853A/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2171895A (en) * | 1937-02-23 | 1939-09-05 | Mcgraw Electric Co | Compensated bimetal thermostat |
| US2363280A (en) * | 1941-05-14 | 1944-11-21 | Westinghouse Electric & Mfg Co | Circuit controller |
| US2425717A (en) * | 1942-06-25 | 1947-08-19 | F A Smith Mfg Company | Thermostatic switch assembly |
| US2432488A (en) * | 1944-03-27 | 1947-12-09 | Sylvania Electric Prod | Glow starter for electric discharge devices |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2879355A (en) * | 1957-06-06 | 1959-03-24 | Hoda Corp | Snap action device |
| US3112384A (en) * | 1959-07-29 | 1963-11-26 | Texas Instruments Inc | Thermal relays |
| US3110788A (en) * | 1959-11-17 | 1963-11-12 | Signal Stat Corp | Automatic re-set thermostatic circuit breaker |
| US3057981A (en) * | 1961-03-23 | 1962-10-09 | Charles V Todoran | Electric socket adapter with fuse plug |
| US3256406A (en) * | 1963-04-25 | 1966-06-14 | Ideal Corp | Single-curved vane-type thermally actuated switch |
| US3275773A (en) * | 1964-04-09 | 1966-09-27 | Grover Products Corp | Over-center snap switch |
| EP0376660A2 (en) * | 1988-12-28 | 1990-07-04 | Otter Controls Limited | Improvements relating to thermal switches |
| EP0376660A3 (en) * | 1988-12-28 | 1991-09-25 | Otter Controls Limited | Improvements relating to thermal switches |
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