EP0172416B1 - A self-protected sheathed resistor - Google Patents
A self-protected sheathed resistor Download PDFInfo
- Publication number
- EP0172416B1 EP0172416B1 EP85109056A EP85109056A EP0172416B1 EP 0172416 B1 EP0172416 B1 EP 0172416B1 EP 85109056 A EP85109056 A EP 85109056A EP 85109056 A EP85109056 A EP 85109056A EP 0172416 B1 EP0172416 B1 EP 0172416B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- switch
- housing
- flange
- heating device
- pushbutton
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0202—Switches
- H05B1/0216—Switches actuated by the expansion of a solid element, e.g. wire or rod
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/78—Heating arrangements specially adapted for immersion heating
- H05B3/82—Fixedly-mounted immersion heaters
Definitions
- This invention relates to a temperature limiter particularly useful with electric heater elements of the sheathed type operating in air and/or liquid media.
- a heating device as claimed comprising a sheathed resistance heating element and temperature controlling and limiting means, so arranged to provide for temperature controlling and limiting effects and thereby protect said sheated resistance heating element against overheating.
Landscapes
- Resistance Heating (AREA)
- Control Of Resistance Heating (AREA)
- Catching Or Destruction (AREA)
- Non-Adjustable Resistors (AREA)
- Materials For Photolithography (AREA)
- Photoreceptors In Electrophotography (AREA)
Abstract
Description
- This invention relates to a temperature limiter particularly useful with electric heater elements of the sheathed type operating in air and/or liquid media.
- As is known, temperature limiters currently known in the art generally operate either on a liquid expansion, or on the differential thermal expansion between two metals, or even, on changes of electric quantities in electronic components.
- In actual practice, prior limiters exhibit difficulties of application and thermal contact with the heater elements owing to theformation, overtime, of oxide or lime or other heat-insulating materials deriving from the type of utilization, whereby the temperature limiter is either caused to be inoperative over time or to operate at different temperature values from the preset ones.
- Temperature limiters which comprise a rod to be used in combination with a sheathed resistor are known, e.g. from GB-A-1408388, GB-A--1223165, GB-A-1010375, GB-A-964355, GB-A-591997 and DE-A-3 401 937.
- The thermal differential expansion between the rod and the sheath of the sheathed resistor results in the opening of the circuit of a switch which interrupts the flow of electric power, thus preventing the resistor from overheating.
- The solutions proposed to obviate the mentioned prior art shortcomings, in particular those related to the use of sheathed electric heating elements in air and/or liquids, have, however, an excessive cost when compared to the cost of the sheathed electric heater element itself to which the temperature limiter is to be applied.
- In the light of such problems, it is a primary object of this invention to obviate the above mentioned drawbacks affecting the prior art by providing a temperature limiter which operates on the principle of the thermal differential expansion of the materials constituting the sheathed heating element to which the limiter is to be applied, in particular, sheathed (armored) electric resistance heating elements operating in air and/or liquids, said limiter being adapted to perform its action always atthe same temperature overtime, without any problems of thermal contact.
- Afurther object of this invention is to exploit said temperature limiter as a safety switch adapted to cut off the electric power supply to the sheathed heating element on exceeding a given temperature and/or as a temperature regulator or safety thermostat for the plurality of uses in which sheathed electric heating elements which can cooperate with the temperature limiter of this invention are required to operate.
- Another object of this invention is to provide a temperature limiter with an extremely simple construction, which can be easily applied to existing sheathed electric heating elements.
- An important object of this invention is to provide a temperature limiter or safety thermostat which is highly reliable and inexpensive.
- These and other objects, such as will be apparent hereinafter, are achieved by a heating device, as claimed comprising a sheathed resistance heating element and temperature controlling and limiting means, so arranged to provide for temperature controlling and limiting effects and thereby protect said sheated resistance heating element against overheating.
- Further features and advantages will be apparent from the following detailed description of a heating device according to the invention, as illustrated by way of example, in the accompanying drawing, where:
- Figure 1 is a perspective view of the heating device according to the invention and incorporating a sheathed heating element of known design (see, e.g. DE-A-3 401 937);
- Figure 2 shows diagrammatically a side view of the switch in the closed circuit position thereof and in normal operation;
- Figure 3 is a side view of the switch of Figure 2 in the open circuit position and with the sheathed resistor in the overheated state thereof; and
- Figure 4 is a partly sectioned front view of the switch of Figures 2 and 3, wherein the pushbutton drawn in solid lines is indicative of normal operation, while the one shown in dashed lines is indicative of the resistor being overheated and the electric circuit opened.
- With reference to the cited figures, the sheathed
electric resistor 10 comprises a tubular metal sheath 11, acoiled resistance heater 12 enclosed in the sheath 11 and embedded in aninsulating material 14. The twoelectric terminals - Close to the
terminals flange 17 to provide a rigid form of connection. There is provided a normally closed contact microswitch, whosehousing 18 is supported on theflange 17 and arigid rod 19 connected, at itsend 20, to themicroswitch housing 18 and, at itsend 21, to thepoint 22 on the sheath. - DE-A-3 401 937 discloses a quite similar structure, whereby, however, the microswitch is maintained closed by the pushing action of the rigid rod. Contrary to said known device, whereby the microswitch housing is rigidly connected to the flange, according to the present invention, a fulcrum means is provided to support the
switch housing 18 on theflange 17, this fulcrum means permitting the rocking movement of theswitch housing 18 relatively to theflange 17. Theswitch housing 18 comprises acontrol pushbutton 23 for the switch itself. Thepushbutton 23 is movable relative theswitch housing 18 and effects, when depressed, opening of the normally closed circuit of the switch. The movement of therod 19 caused by the differential thermal expansion of the sheath 11 causes theswitch housing 18 to rock toward theflange 17 and hence the actuation of the push-button 23 which, under the action from theflange 17 and therod 19, is pushed back into theswitch housing 18 and causes the circuit to be opened. - The fulcrum means which connects the
flange 17 to theswitch 18 comprises, for example, two supportingmembers 31; in the drawing the second supportingmember 31 is not visible, being arranged symmetrically. The supportingmembers 31 may be formed from a small plate bent to a "U", with the base of said "U" attached to theflange 17. The supportingmembers 31 support apin 30 which engages pivotably with theswitch housing 18. Thepin 30 is the fulcrum around which the rocking movement of theswitch housing 18 takes place. Therod 19 is connected to theswitch housing 18 through a hinge connection which enables theswitch housing 18 to rotate around therod 19. The end of the rod 19 (not shown in the drawing) is configured T-like. The two wings of the "T" engage in two seats provided in theswitch housing 18. - The
point 32 of theswitch housing 18 whereto therod 19 is journalled lies preferably between thepin 30 andpushbutton 23. - Electrically conductive elastic means are provided which comprise, for example, a
wire 40 bent to a U-like shape, in order to effect the electric connection of theelectric terminal 41 of the switch andterminal 16 of theresistance heater 12. The elasticity of thewire 40 bent to a U-like shape enables theswitch housing 18 to rock relative to theflange 17 andfulcrum 30. Resetting of the circuit of the switch to the closed condition may take place either manually or automatically. Where resetting is provided automatically, known elastic means not forming a part of this invention, which normally resist actuation of thepushbutton 23, automatically determine, on release of the urge from therod 19, resetting to the closed circuit conditions. Where resetting occurs manually, according to a preferred embodiment of the invention, thepushbutton 23 further comprises elastic locking means adapted to lock thepushbutton 23 in the open circuit position and to resist the action of the cited known elastic means which would tend to close the circuit on removal of the urge from therod 19. The elastic locking means according to this invention comprise apin 50 movable crosswise to the direction of movement of the push-button 23. Thepin 50 engages, under the urge of elastic means of its own, comprising for example thespring 51, into at least oneseat 52 correspondingly provided in the body of theswitch housing 18. Theseat 52 is provided at a relative position between thepushbutton 23 and the switch which causes the electric circuit to be opened. - Preferably, a
second seat 53 for thepin 50 is provided at a relative position between the push-button 23 and the switch such that, whenpin 50 engages into saidsecond seat 53, the electric circuit is closed.
Claims (9)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT85109056T ATE37127T1 (en) | 1984-08-22 | 1985-07-19 | OVERLOAD PROTECTED SHEET RESISTOR. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT8422902U IT8422902V0 (en) | 1984-08-22 | 1984-08-22 | SELF-PROTECTED ARMORED ELECTRIC HEATER. |
IT2290284U | 1984-08-22 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0172416A1 EP0172416A1 (en) | 1986-02-26 |
EP0172416B1 true EP0172416B1 (en) | 1988-09-07 |
EP0172416B2 EP0172416B2 (en) | 1992-08-26 |
Family
ID=11201709
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85109056A Expired - Lifetime EP0172416B2 (en) | 1984-08-22 | 1985-07-19 | A self-protected sheathed resistor |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0172416B2 (en) |
AT (1) | ATE37127T1 (en) |
DE (1) | DE3564899D1 (en) |
IT (1) | IT8422902V0 (en) |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB591997A (en) * | 1944-07-31 | 1947-09-04 | Arthur Harry Walter | Improvements in or relating to thermostatically-controlled electric heating units |
DE1138173B (en) * | 1960-08-04 | 1962-10-18 | Forbach G M B H & Co K G | Temperature protection device for the electric hot water heater or the like. |
US3585359A (en) * | 1969-10-24 | 1971-06-15 | Emerson Electric Co | Electric heating elements |
IT8321433V0 (en) * | 1983-04-05 | 1983-04-05 | Irca Spa | TEMPERATURE LIMITER IN PARTICULAR FOR ELECTRIC HEATING ELEMENTS. |
-
1984
- 1984-08-22 IT IT8422902U patent/IT8422902V0/en unknown
-
1985
- 1985-07-19 AT AT85109056T patent/ATE37127T1/en not_active IP Right Cessation
- 1985-07-19 EP EP85109056A patent/EP0172416B2/en not_active Expired - Lifetime
- 1985-07-19 DE DE8585109056T patent/DE3564899D1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
IT8422902V0 (en) | 1984-08-22 |
EP0172416B2 (en) | 1992-08-26 |
DE3564899D1 (en) | 1988-10-13 |
EP0172416A1 (en) | 1986-02-26 |
ATE37127T1 (en) | 1988-09-15 |
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