Automatic temperature and humidity regulation – Thermostatic – Expanding fluid
Reexamination Certificate
2003-09-30
2004-11-16
Jiang, Chen Wen (Department: 3744)
Automatic temperature and humidity regulation
Thermostatic
Expanding fluid
C123S552000
Reexamination Certificate
active
06817540
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermo element suitable for use in an electronic control thermostat that performs control to vary the water temperature in an engine cooling water temperature control system that variably sets the cooling water temperature in accordance with the load of the internal combustion engine (called the ‘engine’ hereinafter) employed in an automobile or the like, for example.
BACKGROUND ART
Generally, a thermo element functions as an actuator that performs drive control of a thermostat valve or similar by causing a moving piston to advance toward and withdraw from the outside of a wax case in accordance with a change in the volume of thermo wax which is encapsulated in the case as a thermally expanding body. Further, as an example of a thermo element of this type, a thermo element is known which is constituted by providing, in or outside the case, heater means for performing control of the thermo wax temperature so as to permit control of the change in the volume of the thermo wax by means of heat which is generated by heater means.
As an example of a thermo element that comprises heater means of this type, a thermostat actuation member that comprises an electrical-resistance heating element, as illustrated by Japanese Patent Application Laid Open No. H8-222101, for example, is known. This conventional technology involves a wax-type thermal element structure in which an electrical-resistance heating element is disposed so as to be embedded in part of the wax encapsulated in the casing, and connecting wire material, which allows electricity to flow to the electrical-resistance heating element within the wax, is withdrawn in a hermetically sealed state via a harness withdrawal portion which is provided by encapsulating sealing material at an end of the casing.
However, in the case of the above-described conventional thermo element, because a resistive heating element is used as the heater means, not only is it difficult to set the heat generation temperature to a preset target temperature and to maintain and control this temperature, there have also been cases where a controller for performing control of the electrification of the resistive heating element must be provided outside the element and electrification control from the outside is necessary.
Furthermore, in the case of the above-described conventional thermo element, an element with a structure in which a heater made of metal foil is attached to a flat metal plate is employed as the electrical-resistance heating element and this element is simply embedded in the wax so as to face the wax. Because only the plate-shaped surface to which the metal foil of the metal plate is attached generates heat, although heat propagates to parts close to the heat-generating part of this surface, because the interval between the heat-generating part and the inner circumferential surface of the casing is not constant, the propagation of heat inside the casing is non-uniform, and the generation of a temperature variation was inevitable. There was therefore also the problem that it was difficult to efficiently raise the temperature of the whole of the wax encapsulated in the casing with this electrical-resistance heating element.
In addition, because two harnesses to which connecting wire material drawn from the heater means was soldered were withdrawn from a harness withdrawal portion that was formed by integrally molded sealing material, the sealing performance in this part was a problem and there was a risk of wax leaking to the outside as a result of the high pressures generated when the wax encapsulated in the casing expanded as a result of a rise in temperature.
The present invention was conceived in view of this matter, an object thereof being to provide a thermo element which not only permits the temperature of the whole of a thermally expanding body such as wax encapsulated in a case to be efficiently raised by means of heater means, and in which element the structure of a terminal withdrawal portion for controlling the electrification of the heater means from the outside is simple and affords a reliable sealing state, but which also allows control of the electrification of the heater means to be dispensed with.
DISCLOSURE OF THE INVENTION
In order to achieve this object, the thermo element according to the present invention (the invention according to claim
1
) is a thermo element equipped with a thermally expanding body which is encapsulated in a tube-type case and which serves to allow a moving piston to advance toward and withdraw from the outside of the case in accordance with a change in the volume of the thermally expanding body that accompanies a variation in the temperature thereof, and a heating element which is disposed in the case and thermally affects the thermally expanding body, characterized in that the heating element has a substantially tubular shape and is disposed so as to be embedded in the thermally expanding body in a substantially central position in the case; an electrode member, which is connected to an external power supply via a terminal withdrawal portion provided at the end of the case on the opposite side to the piston, is disposed on the inner circumferential side of the heating element; a plate spring member which also serves as a heat radiation fin for radiating heat to the thermally expanding body is disposed at the circumference of the heating element between this circumference and the inside wall portion of the case, the plate spring member having a larger surface area than the heating element.
The thermo element according to the present invention (the invention according to claim
2
) is the thermo element according to claim
1
, characterized in that the terminal withdrawal portion comprises: an insulating tube body which is held at an end of the case in a state where sealing material is interposed between the insulating tube body and the end of the case; and a terminal which is arranged penetratingly within the insulating tube body in a state where sealing material is interposed between the terminal and the insulating tube body, the terminal being electrically connected to an electrode member which is provided in the heating element.
The thermo element according to the present invention (the invention according to claim
3
) is the thermo element according to claim
1
or
2
, characterized in that the plate spring member consists of an electrically conductive material and functions as a second terminal that permits electrical conduction between the heating element and the case by contacting the outer circumference of the heating element and the inside wall portion of the case.
The thermo element according to the present invention (the invention according to claim
4
) is the thermo element according to any one of claims
1
to
3
, characterized in that the electrode member comprises an electrically conductive plate spring member; and spring elements that cause a pressure contact force to act on the inner circumference of the heating element are provided on the electrode member.
The thermo element according to the present invention (the invention according to claim
5
) is the thermo element according to claim
1
, characterized in that the terminal withdrawal portion comprises: an insulating tube body which is held at an end of the case in a state where sealing material is interposed between the insulating tube body and the end of the case; and first and second terminals which are arranged penetratingly within the insulating tube body in a state in which sealing material is interposed between each of these terminals and the insulating tube body, the first terminal being electrically connected to an electrode member which is disposed on the inner circumferential side of the heating element, and the second terminal being electrically connected to at least either the plate spring member disposed on the outer circumferential side of the heating element or the outer circumferential side of the heating element.
The thermo element according to the prese
Aburakawa Masahiro
Suda Hiroshi
Jiang Chen Wen
Nippon Thermostat Co., Ltd.
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