JPH06101627A - Thermoelement - Google Patents

Abstract

PURPOSE:To optionally control the moving quantity of a piston, by heatcontrolling a heating part, heating a thermal expansion body on receiving the moved quantity of the piston, in a unit in which the piston is moved according to volume change due to heating the thermal expansion body. CONSTITUTION:Desired piston moving quantity is set by a piston moving quantity setting circuit 15 to output voltage ER according to the set quantity. When the expended quantity of a piston 12 at a point of this time is made zero, the output voltage ES of a piston moving quantity detection sensor 14 is zero, and a + signal according to the difference (ER-ES) is outputted from a D.C. voltage amplifier 16. Consequently, a transistor TRS3 of a switching circuit 18 is turned ON, electrification is started to a heater 6 from a power amplifier 17, and a piston 12 is extended due to the heating expansion of wax 5. Since the value of the output voltage ES of the sensor 14 increase following the extending, the output of the D.C. voltage amplifier 16 is made zero when ER-ES=0, breaking electrification to the heater 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelement in which a piston expands or contracts depending on whether or not a heat-expanding body is heated.
The present invention relates to a feedback control type thermoelement that controls heating of a thermal expansion body based on the detected movement amount.

[0002]

2. Description of the Related Art Generally, a thermoelement has a case in which a thermal expansion body such as wax that expands and contracts due to a temperature change is built in, and a volume change of the thermal expansion body operates an operating portion such as a piston. It is used as an actuator for operating various devices such as a temperature-sensitive automatic valve for adjusting the cooling water temperature of an internal combustion engine and a temperature-sensitive switch.

[0003]

However, in the conventional thermoelement, a plurality of waxes having different thermal expansion coefficients are appropriately mixed to obtain a desired piston stroke. However, the wax as the thermal expansion body is a case. The piston stroke cannot be changed after it is enclosed because it is built in and is in the sealed state.Also, the piston stroke as an error due to the secular change of the thermoelement, that is, deterioration of the thermal expansion body and friction of the moving parts Since there is no particular measure to deal with the change, it is unavoidable that the accuracy in the operation of the device is deteriorated during long-term use. Further, when waiting for the piston to contract due to contraction of the heated thermal expansion body due to natural cooling, there is a problem in that the piston may not be contracted promptly. Further, when the heating of the thermal expansion body is stopped to cause the piston to retract, there is a problem that the piston may be caught in the middle due to friction and the contraction of the piston may not follow the contraction of the thermal expansion body smoothly. It was

The present invention was devised in order to solve the above-mentioned problems, and it is possible to arbitrarily control the piston movement amount by receiving feedback of the piston movement amount. The purpose is to provide a thermoelement that can operate the equipment with high accuracy for a long period of time without being affected by the error that should occur due to changes, and also to quickly retract the piston after heating is stopped. The purpose is to provide a thermoelement that can Further, another object of the present invention is to provide a thermoelement that can smoothly and surely retract the piston.

[0005]

In order to solve the above problems, the present invention incorporates a thermal expansion body which expands by heating and contracts by stopping heating in a case. In the thermoelement that takes out the volume change of the expansion body as the movement of the piston for operating the equipment,
A heating unit for heating the thermal expansion body, a piston movement amount detection unit for detecting the movement amount of the piston, and a movement amount of the piston detected by the piston movement amount detection unit, and the heating unit. And a piston movement amount setting unit capable of arbitrarily controlling the movement amount of the piston by performing the heating control.

Further, in a thermoelement, a thermal expansion body which expands when heated and contracts when heating is stopped is built in a case, and a volume change of the thermal expansion body is taken out as movement of a piston for operating a device. , A heating / cooling unit for heating and cooling the thermal expansion body, a piston movement amount detection unit for detecting the movement amount of the piston, and a piston movement amount detected by the piston movement amount detection unit. And a piston movement amount setting unit that can arbitrarily control the movement amount of the piston by performing heating / cooling control of the heating / cooling unit.

Further, an elastic body, in which an elastic force is applied to the piston in the contracting direction of the piston, is arranged in the piston portion.

[0008]

[Operation] The heating unit heats the thermal expansion body by controlling the heating of the piston movement amount setting unit. This heating causes the thermal expansion body to expand, and the piston extends accordingly. The extension of the piston is detected by the piston movement amount detection unit, and the detection data is sent to the piston movement amount setting unit one by one. The piston movement amount setting unit receives the sending data and controls to stop the heating of the thermal expansion body when the piston reaches a predetermined extension amount set in advance. As a result, expansion of the thermal expansion body stops and extension of the piston stops. That is, the piston extends to the extension amount preset by the piston movement amount setting unit and stops.

Further, when the heating of the thermal expansion body is stopped and the piston is retracted, the thermal expansion body which is heated and has heat is cooled to accelerate the contraction of the thermal expansion body.
Therefore, the retracting operation of the piston becomes faster accordingly. Further, due to the action of the elastic force of the elastic body arranged in the piston portion, the piston is smoothly and reliably retracted without being stopped by being caught on the way.

[0010]

Embodiments of the present invention will be described with reference to the drawings.
Hereinafter, the description from the first embodiment to the third embodiment will be sequentially performed. First, FIG. 1 shows the configuration of the first embodiment, showing a vertical cross-sectional view of a thermoelement in which each part is formed in a cylindrical shape as a whole and an electric circuit diagram mounted on a substrate (not shown). There is. In the first embodiment, a heater provided in the wax case is used to heat the wax as the thermal expansion body, and after the heating by the heater is stopped, an electronic cooling element provided at the bottom of the wax case is used. By cooling the wax with the wax, the piston can be contracted quickly.

In the figure, reference numeral 1 is a thermoelement, and the thermoelement 1 includes a wax case 2 containing a wax 5 as a thermal expansion body, an operating part guide 3,
Also, it is roughly configured from the operating unit 4. Of these, the wax case 2 is provided with a heater 6 for heating the wax 5 on its inner peripheral surface. When a current is passed through the heater 6, heat is generated to heat the wax 5. ing. Further, an electronic cooling unit 7 formed of a semiconductor element and having a cooling capacity is provided on the bottom surface of the wax case 2, and the electronic cooling unit 7 is provided with:
By supplying an electric current from an electric circuit described later, the bottom surface of the wax case 2 is cooled and the heated wax 5 is cooled. Reference numerals 7a and 7b are heat absorbing / radiating fins of the electronic cooling unit 7.

The principle of cooling by the electronic cooling unit 7 is based on the well-known Peltier effect. To explain the principle in general, if two different kinds of metals or semiconductors are connected in series and a current is passed, Heat generation and heat absorption, that is, a cooling phenomenon occurs at this joint. In this case, if the direction of the flowing current is reversed, heat generation and absorption also occur at the opposite positions, and the amount of heat generated and the cooling capacity can be changed by changing the value of the flowing current.

Referring again to FIG. 1, reference numeral 8 is a diaphragm for transmitting the expansion force of the heated wax 5 to the operating portion 4 via the semi-fluid body 9. That is, when the wax 5 expands due to the heating of the heater 6, the expansion force pushes the diaphragm 8 upward, and the pressing force is applied to the semi-fluid body 9, the rubber piston 10, and the resin plate 1.
1, and is transmitted to the piston 12, and a required device operation is performed by the extension output of the piston 12. Actuator guide 3
Surrounds the operating portion 4 having the above-mentioned configuration and guides the operation. That is, the operating portion guide 3 is joined to the wax case 2 by a fitting or caulking process at the lower portion A of the operating portion guide 3, and the spring 13 as the elastic body is arranged above the operating portion guide 3. Space B is formed. This spring 13 is
The elastic force is urged in the retracting direction (downward direction of the drawing) of the piston 12 at the locking portion C by being wound around the upper portion having a small diameter, and the urged elasticity is exerted. Due to the force, when the piston is retracted, the piston is smoothly and reliably retracted without being caught on the way due to friction or the like. In addition, the uppermost part D of the operating part guide 3
The part is formed with the smallest diameter in the operating part guide 3,
A piston movement amount detection sensor 14 that detects the movement amount of the piston 12 and sends out a voltage or current according to the detected movement amount is fitted on the outer peripheral surface of this portion.

Next, an electric circuit portion mounted on a substrate (not shown) will be described. Reference numeral 15 is a piston movement amount setting circuit, and when a desired piston movement amount is set, a voltage ER corresponding to this set amount is output. Reference numeral 16 is a DC voltage amplifier for receiving a differential voltage between the output voltage ER from the piston movement amount setting section and the output voltage ES corresponding to the movement amount of the piston output from the piston movement amount detection sensor 14 and amplifying it. is there. 17
Is a power amplifier that receives the output of the DC voltage amplifier 16 and amplifies it, and amplifies the power for heating the heater 6. Further, 18 is a transistor TRS1, TR
S2 and TRS3 are provided, and an electric current is applied to the electronic cooling unit 7 when cooling the thermal expansion body, and the heater 6 is used when heating.
It is a switching circuit that switches an electric circuit so that a current flows through it.

In the thermoelement constructed as described above, first, the desired piston movement amount is set by the piston movement amount setting circuit 15. When this setting is performed, the voltage ER corresponding to the set amount is output, but if the amount of extension of the piston 12 at this point is zero, the output voltage ES from the piston movement amount detection sensor 14 is zero. , The differential voltage becomes ER -ES> 0, and the output of the DC voltage amplifier 16 becomes positive. Therefore, the transistor TRS3 of the switching circuit 18 is turned on, whereby the power from the power amplifier 17 is applied to the heater 6, the wax 5 is heated, and the piston 12 extends. As the piston 12 extends, the piston movement amount detection sensor 1
The output voltage ES from 4 rises. Then, when the value of the output voltage ES becomes the differential voltage ER-ES = 0, the output of the DC voltage amplifier 16 becomes zero. As a result, the transistor TRS3 is turned off and the output from the power amplifier 17 to the heater 6 is also cut off, so that the wax 5
Is stopped, and the extension of the piston 12 is also stopped by stopping this heating.

On the other hand, when the set voltage ER set by the piston movement amount setting circuit 15 is reduced to ER-ES <0, the output of the DC voltage amplifier 16 becomes negative, so that the transistor TRS1 of the switching circuit 18 is turned off. ， TRS2 is O
As a result, the electric current flows through the electronic cooling unit 7 and the wax case 2 is cooled. The wax 5 contained in the wax case 2 by this cooling
Are cooled and contract. Following this contraction, piston 1
2 shrinks, but in this shrinkage of the piston 12,
Due to the action of the elastic force of the spring 13 arranged on the piston 12, the retraction is smoothly and reliably performed without being caught in the middle. The output voltage ES of the piston movement amount detection sensor 14 also decreases due to the contraction of the piston,
In this case, the piston 12 has the differential voltage ER -ES = 0.
Degenerate until. As described above, the piston 12 always outputs the voltage ER corresponding to the piston movement amount set by the piston movement amount setting circuit 15 and the piston 12 detected by the piston movement amount detection sensor.
It will stand still under the condition that the output voltage ES corresponding to the amount of movement of is equal.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing the configuration of the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the wax 5 is heated not only by the electronic cooling unit 7 of the first embodiment without using a heater, but also by heating. The point is that the switching circuit 18 of the circuit portion is omitted. That is, this electronic cooling unit 7
Uses the principle of the Peltier effect as described above, and has a cooling capacity on one side and a heating capacity on the other side. In the second embodiment, the wax is heated by utilizing this heating ability. As described above, by adopting a configuration in which heating and cooling are performed by an electronic element, it is possible to expect an effect that a thermoelement having a longer life can be realized while facilitating the manufacture and reducing the number of failures.

In FIG. 2, as described above, the thermoelement 1 in the second embodiment is different from the heater 6 in the first embodiment only in that the switching circuit 18 of the electric circuit portion is omitted, and the other components are the same. The structure is basically the same as that of the first embodiment. That is, reference numeral 15 is a piston movement amount setting circuit, and when a desired piston movement amount is set, a voltage ER corresponding to this setting amount is output. 20
Is the output voltage ER from this piston movement amount setting circuit 15.
And a voltage difference ES from the piston movement amount detection sensor 14 and a voltage ES depending on the movement amount of the piston, and amplifies the voltage difference. Reference numeral 21 is a power amplifier that amplifies a positive or negative voltage to be output to the electronic cooling unit 7. In the electronic cooling unit 7, in this embodiment, the joint surface with the wax case 2 is heated by the application of the positive voltage, and the joint surface with the wax case 2 is conversely cooled by the application of the negative voltage.

In the above construction, first, when a desired piston movement amount is set by the piston movement amount setting circuit 15, a voltage ER corresponding to this setting amount is output.
If the differential voltage from the output voltage ES from the piston movement amount detection sensor 14 at this time point is ER-ES> 0, a positive voltage is output from the power amplifier 21 and applied to the electronic cooling unit 7. By the application of this positive voltage, the electronic cooling unit 7 heats the wax case 2 at the joint surface with the wax case 2 as described above, and the wax 5 is heated and expanded by this heating. This expansion causes the piston 12 to extend. By the extension of the piston 12, the piston movement amount detection sensor 1
When the output voltage ES from 4 rises and ER-ES = 0, the output of the power amplifier 21 is stopped, whereby the heating of the wax case 2 by the electronic cooling unit 7 is also stopped. By stopping this heating, extension of the piston 12 also stops. That is, the piston 12 stands still under the condition of ER = ES.

On the other hand, the set voltage ER set by the piston movement amount setting circuit 15 is decreased so that the differential voltage becomes ER-ES <
When it becomes 0, the output voltage of the power amplifier 21 becomes negative. When this negative output voltage is applied to the electronic cooling unit 7, as described above, the wax case 2
The wax case 2 is cooled by the cooling of the joint surface of the wax case 2. By this cooling, the wax 5 is cooled and contracts, and the piston 12 also contracts following the contraction of the wax. In this case, the piston 12 has the differential voltage ER -E.
It degenerates to a position where S = 0, stops, and then stops at this position. When the piston 12 is contracted, the piston 12 is contracted smoothly and surely to a predetermined position without being caught in the middle by the elastic force of the spring 13 arranged in the piston 12 portion as in the first embodiment. .
In this way, the piston 12 remains stationary under the condition that ER = ES.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing the configuration of the third exemplary embodiment of the present invention. The third embodiment has a simple structure in which the electronic cooling unit 7 is removed from the first embodiment and the heated wax is cooled naturally. Accordingly, the switching circuit 18 for switching the circuit for applying the voltage to the electronic cooling unit 7 in the first embodiment is omitted. The DC voltage amplifier 16 and the power amplifier 17 in the first embodiment are collectively shown as a DC voltage / power amplifier 22.

Output V0 of this DC voltage / power amplifier 22
Is the voltage V0 for heating the heater 6 only under the condition that the differential voltage between the output voltage ER of the piston movement amount setting circuit 15 and the output voltage ES from the piston movement amount detection sensor 14 is ER-ES> 0, that is, positive. Is output. In FIG. 3, first, when a desired piston movement amount is set by the piston movement amount setting circuit 15, a voltage ER corresponding to this setting amount is output. At this time, the differential voltage from the output voltage ES from the piston movement amount detection sensor 14 is E
If R-ES> 0, the heater 6 is heated by the output of the DC voltage / power amplifier 22, the wax 5 is expanded by this heating, and the piston 12 is extended by this expansion force. Due to the extension of the piston 12, the output voltage ES from the piston movement amount detection sensor 14 rises and ER -E
DC voltage / power amplifier 22 when S = 0
Output is stopped, heating of the heater 6 is also stopped, and extension of the piston 12 is stopped. That is, the piston 12 stands still under the condition of ER = ES as in the above embodiment.

On the other hand, the set voltage ER by the piston movement amount setting circuit 15 is decreased so that the differential voltage becomes ER-ES <
When it becomes 0, the wax 5 is not heated, the wax 5 shrinks by natural cooling, and the piston 12 also shrinks following this shrinkage. In this case, due to the elastic force of the spring 13 arranged in the piston 12, the piston 12 is smoothly and surely retracted without being caught on the way. The output voltage ES of the piston movement amount detection sensor 14 also decreases due to the contraction of the piston 12, and the piston 12 contracts and stands still to the position where the differential voltage ER -ES = 0 is the same as in the above-described embodiment. is there.

[0024]

As described above, according to the present invention, the heating portion for heating the thermal expansion body contained in the case, the piston movement amount detection portion for detecting the movement amount of the piston, and the piston movement amount detection The amount of piston extension can be controlled by a configuration that includes a piston movement amount setting unit that can control the amount of movement of the piston by controlling the heating of the heating unit by receiving data from the unit. Therefore, the thermoelement can be operated with high accuracy for a long period of time without being affected by an error that should occur due to the secular change of the thermoelement. In addition, the structure that accelerates the contraction of the thermal expansion body by cooling the thermal expansion body after the heating is stopped enables the piston to perform the contracting operation quickly, and the elastic force is applied in the contracting direction of the piston. With the configuration in which the elastic body is provided on the piston, the thermoelement can be smoothly and reliably retracted without being caught by the piston due to friction or the like when the piston retracts.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

[Explanation of symbols]

 1 ・ ・ Thermo element 2 ・ ・ Wax case 3 ・ ・ Operating part guide 4 ・ ・ Operating part 5 ・ ・ Wax 6 ・ ・ Heater 7 ・ ・ Electronic cooling unit 7a, 7b ・ Suction / radiating fin 8 ・ ・ Diaphragm 9 ・ ・Semi-fluid 10, Rubber piston 11, Resin plate 12, Piston 13, Spring 14, Piston movement amount detection sensor 15, Piston movement amount setting circuit 16, DC voltage amplifier 17, Power amplifier 18, Switching circuit 20, DC voltage amplifier 21, power amplifier 22, DC voltage, power amplifier

Claims (3)

[Claims] 1. A thermoelement in which a thermal expansion body that expands when heated and contracts when heating is stopped is built in a case, and a volume change of this thermal expansion body is taken out as movement of a piston for operating a device. A heating unit for heating the thermal expansion body, a piston movement amount detection unit for detecting the movement amount of the piston, and a heating unit that receives the movement amount of the piston detected by the piston movement amount detection unit. And a piston movement amount setting unit capable of arbitrarily controlling the movement amount of the piston by controlling heating of the portion. 2. A thermoelement in which a thermal expansion body which expands when heated and contracts when heating is stopped is built in a case, and a volume change of this thermal expansion body is taken out as movement of a piston for operating a device. A heating / cooling unit for heating and cooling the thermal expansion body; a piston movement amount detection unit for detecting the movement amount of the piston; and a piston movement amount detected by the piston movement amount detection unit. And a piston movement amount setting unit capable of arbitrarily controlling the movement amount of the piston by performing heating / cooling control of the heating / cooling unit. 3. An elastic body in which an elastic force is applied in the direction of contraction of the piston is arranged in the piston portion so that the piston can be reliably contracted when the thermal expansion member contracts. The thermoelement according to claim 1 or 2, characterized in that