Margaryan, Hayk (Mananjyan str, 1-17 Yerevan, 6, 37500, AM)
| 1. | A temperature controller, comprising a cover and a base, made of an electrically insulating material, such as a plastic, and forming a space with a thermally sensitive element mounted therein, with the said element having a Ushaped profile made of bimetal strip, the said strip having one end attached to a mechanical tension regulator inside the bimetal body, while the other free end having a permanent magnet attached thereon; a displacement transfer element transferring the displacement of the said thermally sensitive element to two movable contacts secured on a conducting bar supported by a spring; two fixed contacts attached to terminals and allowing interaction with the said movable contacts; a magnetic interaction gap adjustment assembly made of ferromagnetic material and disposed opposite the said permanent magnet; characterized by that the mechanical tension regulator inside the bimetal body is realized as a branch piece of the said base, having a Ushaped profile and positioned in the space bounded by a Ushaped profile of the said thermally sensitive element, the said branch piece having the free end attached to the strip of thermally sensitive element and a spring mounted between the end of said branch piece, while the ends are connected by a displacement transfer element moving the free end relative to the fixed end, the said transfer element being made of an electrically insulating material, in form of a bar continuing the said bimetal strip, while the displacement transfer element bears a springsupported conducting plate. |
| 2. | A temperature controller according to claim 1, characterized by that the said branch piece of base having a Ushaped profile is mounted in inclined position inside the space formed by the said thermally sensitive element. |
| 3. | A temperature controller according to claim 1, characterized by that the said displacement transfer element moving the free end relative to the fixed end of the branch piece is embodied as a screw pair. |
| 4. | A temperature controller according to claim I5 characterized by that the said magnetic interaction gap adjustment assembly is embodied as a stopper screw. |
| 5. | A temperature controller according to claim 1, characterized by that the said spring supported conducting plate is positioned transversally to the said transfer element bar. |
Technical Field
The present invention relates to automatic temperature stabilization and control devices, embodied as a switch either closing or opening the electrical circuit of a heating or cooling apparatus connected thereto. Known are the temperature controllers having thermally sensitive elements made of variously bent bimetal strips, which produce a snap-switching operation at a certain critical temperature due to magnetic interaction forces. A bimetal strip held by the magnetic interaction forces accumulates energy as the temperature is varied. When the critical temperature is reached, the magnetic interaction force and the force generated by thermal stress in the bimetal strip become equal, while the accumulated energy provides snap action. Background Art
Known is the thermal controller [1] having its thermally sensitive element in form of a bimetal strip twisted into a spiral, in which one end is movable and has a permanent magnet attached thereto, while the other end can be adjustably secured. The permanent magnet attached to the movable end of bimetal strip interacts with a counterpart magnetic element, enacting the motion of a rod inside a separately positioned magnetic switch, fixed in one of two stable states determined by the temperature. The shortcoming of this thermal controller is complexity of its structure.
The closest prior art taken as a prototype is the thermal controller [2], comprising a cover and a base, both made of an electrically insulating material, say a plastic, and forming a space including a thermally sensitive element positioned therein, in form a U-shaped bimetal strip having one end attached to a mechanical stress regulator inside the bimetal body and the other end free and having a permanent magnet attached thereon; a motion transfer element from the thermally sensitive element to two movable contacts attached to an electrically conducting bar supported by a spring; two fixed contacts attached to terminals, mounted to provide interaction of fixed and movable contacts; magnetic gap width adjustment assembly made of a ferromagnetic material and positioned in front of a permanent magnet. The shortcoming of this thermal controller is complexity of its structure, due to the presence of a mechanical stress regulator inside the bimetal body and high precision of its embodiment. Disclosure of the Invention
It is the purpose of this invention to design a temperature controller having simpler structure than in the prior art.
For effecting this purpose, the following modification are introduced in the know thermal controller comprising a cover and a base, both made of an electrically insulating material, say a plastic, and forming a space including a thermally sensitive element positioned therein, in form a U-shaped bimetal strip having one end attached to a mechanical stress regulator inside the bimetal body and the other end free and having a permanent magnet attached thereon; a motion transfer element from the thermally sensitive element to two movable contacts attached to an electrically conducting bar supported by a spring; two fixed contacts attached to terminals, mounted to provide interaction of fixed and movable contacts; magnetic gap width adjustment assembly made of a ferromagnetic material and positioned in front of a permanent magnet:
Mechanical stress regulator inside the bimetal body is realized as a U-shaped in profile branch piece of the base, positioned inside the space bounded by a U-shaped profile of thermally sensitive element. Movable end of the said branch piece has bimetal strip of thermally sensitive element attached thereto.
A spring is used between the branch piece ends, while the ends themselves are connected by a transfer element displacing the movable end relative to the fixed end.
The said transfer element is made of electrically insulating material, in form of a band continuing the bimetal strip. The spring-supported conducting bar is mounted on the transfer element.
The proposed temperature controller also has distinguishing features in that the U-shaped profile of the base branch piece is positioned inclined in the space formed by the thermally sensitive element; the transfer element displacing the movable end relative to the fixed end is implemented in form of a screw pair; the magnetic gap width adjustment assembly is realized in form of anchored screw; while the spring-supported conducting bar is positioned transversally to the band of transfer element.
Fig. 1 is a section through a temperature controller; Fig. 2 is a section along the I - I axis; Fig. 3 is cross section in the domain of transfer element including the spring-supported conducting bar and movable contacts. Temperature controller of the invention, comprising a base 1 and cover 2, generally made of an electrically insulating material, and particularly of a plastic, and forming a space in which a thermally sensitive element is positioned, having a U-shaped profile and made of a bimetal strip 3, with a permanent magnet 5 attached to the end 4; a displacement transfer element 6, generally made of an electrically insulating material and shaped as a band continuing the bimetal strip 3 and having a conducting bar transversally attached thereon, being supported by a spring 7 and bearing movable contacts 8. The other end of bimetal strip 3 is attached to a mechanical stress regulator in bimetal body. The said mechanical stress regulator is embodied as a branch piece 11 of base I 5 having a U-shaped profile, a movable end 12 and a fixed end 13, with a spring 14 mounted between the ends, connected also by a screw 16 having a collar 15 designed to adjust the gap width between the ends 12 and 13, while the end 10 of a thermally sensitive strip 3 is connected with the movable end 12 of the branch piece 11. The branch piece 11 has stiffening ribs 17 provided thereon and is positioned in the space formed by the thermally sensitive strip 3, in such a way that the surfaces forming the U-shaped profile are oriented in the same direction, while the symmetry axes of the U-shaped elements are intersecting. A magnetic interaction gap width regulator 18 is mounted in the body of base I 5 in a position allowing interaction with a permanent magnet 5, realized as a stopper screw made of a soft ferromagnetic material. The poles of the permanent magnet 5 are aligned along the course axis of the screw 18 adjusting the gap width of magnetic interaction. For example, if the end of a permanent magnet 5 adjacent to the thermally sensitive bimetal strip 3 has S-polarity, then the end opposite the screw 16 has N- polarity, and vice- versa. Terminals 20 bearing fixed contacts 19 thereon are mounted in the body of base I 5 allowing interaction of the movable contacts 8 with fixed contacts 19. Same-axis openings 21 are provided in the body of base 1 and cover 2 for mounting. The narrow part of the base 1 end has normally extended ridges 22 which facilitate mounting of the cover 2, while the protrusion located over the terminals plays also the role of a limiter for displacement of the transfer element 6. Thermal exchange windows 23 are provided in the body of cover 2.
The proposed execution of mechanical stress regulator inside the bimetal body provides a simpler structure of the temperature controller.
Indeed, regulation of mechanical stress in the bimetal body, and thus control of the stabilized temperature, is performed both in the prototype and in the present invention by deflection of the bimetal strip end attached to the regulator from a certain direction, through rotation around a certain axis. Selection of the rotation axis determines the character of controlled temperature dependence on the deflection value. It is preferable that this dependence shall have a linear character.
Embodiment of these tasks is reached in the prototype by means of a complicated and multi- element structure of the temperature controller.
In the proposed temperature controller, the collar 15 of the screw 16 securely fixes the end 10 of bimetal strip 3 on the movable end 12 of the branch piece 11. Deflection of the end 10 of
bimetal strip 3 is performed by simple turn of the screw 16 and is fixed in the desired position by a spring 14. Inclined position of the branch piece 11 strengthened by rigidity ribs 17 forms a virtual axis, the rotation around which provides linear dependence of temperature on the deflection value. The displacement transfer element 6 made of electrically insulating material, in form of a band continuing the bimetal strip 3, and transversal mounting of a spring-supported conducting bar 9 thereon, having movable contacts 8, provide the following advantages:
• electrical insulation of the bimetal strip 3;
• a simpler mechanism of bimetal strip displacement transfer to movable contacts; • optimal disposition of movable contacts 8 and fixed contacts 19.
Magnetic interaction gap regulator embodied in form of a stopper screw 18 reduces the mass and makes easier the adjustment of temperature controller.
Temperature controller of the present invention may be embodied both with normally closed and normally open contacts. Both heating and cooling appliances may be connected for control. Operation principle of the proposed temperature controller is independent of the above factors.
For definiteness, only the temperature controller with normally closed contacts will be considered below, with a heating appliance being connected thereto.
Stopper screw 18 is used to select the gap width of magnetic interaction for the given position of contacts and range of stabilized temperature, in process of the temperature controller adjustment. No adjustment is allowed during operation. In the considered example, the initial temperature of controlled appliance should be clearly lower than the initial temperature of stabilization range.
Stabilized temperature of the controlled appliance is set by turning of the screw 16, until the mark provided thereon is coincident with a value indicated on the scale of cover 2 (not shown in the accompanying figures).
As the temperature is increased, the end 4 of bimetal strip 3 tends to move in the direction normal to the strip and disconnect the contacts. However, the magnetic attraction force of the magnet 5 and the element 18 retain the end 4 in the initial position. During this process, the bimetal strip 3 does not perform any work and accumulates mechanical energy. When the stabilization temperature is reached, the energy accumulated in the bimetal strip becomes sufficient to perform work against the magnetic attraction force. The force deflecting the end 4 becomes equal to the retaining magnetic force, moving the end 4 increasing the gap width between the magnet 5 and the element 18. Since the magnetic attraction force strongly falls, as the distance between the magnet and the attracted body is increased, while the deflecting force determined by the temperature is independent of the distance, the displacement of the end 4 is effected with acceleration. The bar 9 with movable contacts 8 also undergoes accelerated motion, disconnecting with a snap the electrical circuit of appliance.
When the temperature is decreased, the described events occur in inverse succession. However, the repeated on-switching of the appliance circuit takes place at a lower stabilization temperature, due to hysteretic effect.
It should be noted that the end of closing and the start of opening processes take place in the most favorable mode, since the spring 7 eliminates the possible chatter of the contacts.
Temperature controllers manufactured on basis of the present invention had the following characteristics: • range of the stabilized temperature (or action temperature ): 0 to 70 C;
• hysteresis (return temperature): 3 to 6° C;
• weight, max 12 grams
Prior art publications:
1. US Patent no. 6707371, Int. CL 7 HOlH 37/66, 16 March 2004.
2. DE Patent no. 198 01258, Int. Cl. 7 HOlH 37/66, 12 Aug. 1999.