Thermoelement

Abstract

[Problem] To provide a thermoelement with a piston that plunges and retracts in association with volumetric expansion of a volumetrically-expanding body, reducing actuation failures in a mechanical mechanism without the use of a complex electrical control mechanism. [Solution] This thermoelement is characterized by comprising: a vessel; a volumetrically-expanding body which is accommodated in the vessel and which undergoes volumetric expansion and volumetric contraction in response to ambient temperature changes; a first piston that is actuated by a change of volume in the volumetrically-expanding body in response to an ambient temperature change in the vessel; a second piston, of a different diameter than the first piston, that is actuated by a change of volume in the volumetrically-expanding body in response to an ambient temperature change in the vessel; a first sealing member disposed at one end of the vessel and having a first through-hole; and a second sealing member disposed at the other end of the vessel and having a second through-hole of a different diameter than the first through-hole, wherein the first piston slides freely through the first sealing member, the second piston slides freely through the second sealing member, and the leading ends of the first and second pistons contact each other, directly or indirectly, inside the vessel.

Description

Thermoelement

[0001] The present invention relates to a thermoelement, and more particularly to a thermoelement used in a thermostat device or the like.

[0002] Conventionally, thermostat devices (also called thermoactuators) have been used to open and close valves in cooling systems for automobiles, etc., using thermoelements that incorporate a thermal expansion body that expands and contracts in response to temperature changes in the object being detected and that have a piston that is actuated by changes in the volume of the thermal expansion body.

[0003] In extremely cold environments such as those found in North America, conventional exhaust heat recovery devices remove the heat from the exhaust gases generated when starting an engine, such as a car, through a heat exchanger. This causes the moisture contained in the exhaust gases to freeze inside the muffler due to the outside air, preventing the exhaust gases from being properly discharged.

[0004] As a countermeasure for this, for example, an electrically controlled thermoactuator as disclosed in Patent Document 1 is used.

[0005] Conventional electrically controlled thermoactuator structures have a mechanism in which a heater is installed inside the thermoelement, and when electricity is applied to the heater in an extremely low temperature environment, the wax, which is a thermal expansion material inside the thermoelement, is forcibly melted, causing the wax to expand in volume, thereby pushing up and operating the piston.

[0006] Patent No. 7126475

[0007] However, in the mechanism of Patent Document 1, when the heater is energized, the heat from the heater is not transferred to the wax in the housing cup but escapes to the metal cup portion due to the balance of thermal conductivity, and the desired operation cannot be obtained.

[0008] The present invention has been devised to solve the above problems, and its purpose is to provide a thermoelement that reduces malfunctions using a mechanical mechanism without using a complex electrical control mechanism, and improves the degree of freedom in the amount of protrusion and recession by allowing the piston to protrude and retract into the housing cup depending on the degree of volumetric expansion of the volumetric expansion body.

[0009] A thermoelement according to a first aspect of the present invention is a thermoelement comprising: a container; a volume expansion body housed in the container and which expands and contracts in volume with changes in ambient temperature; a first piston that operates in response to a change in volume of the volume expansion body with changes in the ambient temperature of the container; a second piston that has a different diameter from the first piston and operates in response to a change in volume of the volume expansion body with changes in the ambient temperature of the container; a first sealing member that is disposed at one end of the container and has a first through hole; and a second sealing member that is disposed at the other end of the container and has a second through hole whose diameter is different from that of the first through hole, wherein the first piston slidably passes through the first sealing member and the second piston slidably passes through the second sealing member, and wherein tips of the first piston and the second piston come into direct or indirect contact with each other within the container.

[0010] The thermoelement according to the second invention is characterized in that, in the first invention, a first biasing force from a first biasing member and a second biasing force from a second biasing member are respectively biased in a retreating (returning) direction on the first piston and the second piston, and the magnitude of the first biasing force is greater than the second biasing force.

[0011] The thermo-element according to the third invention is characterized in that, in the second invention, the relationship between the first biasing force and the second biasing force is configured to satisfy the following relational expression (1):

[0012] A thermo-element according to a fourth aspect of the present invention is the thermo-element of the third aspect, characterized in that it has a locking structure that stops the first piston at a predetermined protruding / retracting amount even when the ambient temperature rises.

[0013] The thermoelement according to the fifth invention is the thermoelement according to the fourth invention, characterized in that the first piston is provided with a stopper to prevent the first piston from entering the container more than a predetermined distance.

[0014] The thermoelement according to the sixth invention is characterized in that, in the fifth invention, the first sealing member and the second sealing member are integrally formed as a sealing member, and the first piston and the second piston are configured to come into direct or indirect contact with each other within a through hole of the sealing member.

[0015] The thermoelement according to the seventh invention is the thermoelement according to the fifth or sixth invention, characterized in that the second piston has a cover equipped with a stopper mechanism to prevent the second piston from sinking to a predetermined extent.

[0016] The thermoelement according to the eighth invention is the thermoelement according to the fifth or sixth invention, characterized in that the second piston is provided with a stopper mechanism to prevent the second piston from sinking to a predetermined extent.

[0017] The thermoelement according to the ninth invention is characterized in that, in the fifth or sixth invention, it has a lid on the first piston side that moves integrally with the container, and is configured so that the stopper and the lid are engaged by the first biasing member.

[0018] According to the first to ninth inventions, it is possible to realize a thermoelement with improved freedom in the amount of protrusion and recession by using a mechanical mechanism to reduce malfunctions without using a complex electrical control mechanism and by protruding and recessing the piston into the cup according to the degree of volume expansion of the volume expansion body.

[0019] FIG. 1 is a cross-sectional view showing the configuration of a thermoelement according to an embodiment of the present invention. FIG. 2(a) is a diagram illustrating the operation of the thermoelement in response to changes in ambient temperature shown in FIG. 1, and FIG. 2(b) is a diagram illustrating the state of FIG. 2(a). FIG. 3 is a characteristic diagram showing the relationship between the temperature of the thermoelement shown in FIG. 2(a) and the amount of protrusion and recession. FIG. 4 is a characteristic diagram showing the relationship between the temperature of the thermoelement shown in FIG. 2(a) and the wax volume. FIG. 5(a) is a detailed explanatory diagram illustrating the operation of FIG. 2(a) in a temperature range between A and B°C, and FIG. 5(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and recession in the temperature range between A and B°C. FIG. 6(a) is a detailed explanatory diagram illustrating the operation of FIG. 2(a) in a temperature range between B and C°C, and FIG. 6(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and recession in the temperature range between B and C°C. FIG. 7(a) is a detailed explanatory diagram of the operation image of FIG. 2(a) at C°C, and FIG. 7(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and depression at C°C. FIG. 8(a) is a detailed explanatory diagram of the operation image of FIG. 2(a) in the temperature range C-D°C, and FIG. 8(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and depression in the temperature range C-D°C. FIG. 9(a) is a detailed explanatory diagram of the operation image of FIG. 2(a) at D°C, and FIG. 9(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and depression at D°C. FIG. 10(a) is a detailed explanatory diagram of the operation image of FIG. 2(a) in the temperature range D-E°C, and FIG. 10(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and depression in the temperature range D-E°C. Fig. 11(a) is a detailed explanatory diagram of the operation image of Fig. 2(a) above E°C, and Fig. 11(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and retraction when operating above E°C. Fig. 12 is a conceptual diagram of the use of a thermoactuator to which the present invention is applied, where (a) is when the cooling water is low temperature, (b) is when the cooling water is medium temperature, and (c) is when the cooling water is high temperature. Fig. 13 is a cross-sectional view showing the configuration of a thermoelement according to another embodiment of the present invention. Fig. 14 is a characteristic diagram showing the relationship between the temperature of a conventional thermoelement and the amount of protrusion and retraction.

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermoelement according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0021] The thermoelement of this embodiment comprises a container (housing cup), a volume expansion body housed in the container and whose volume expands and contracts with changes in ambient temperature, a first piston that operates in response to a change in the volume of the volume expansion body with changes in the ambient temperature of the container, a second piston of a different diameter than the first piston that operates in response to a change in the volume of the volume expansion body with changes in the ambient temperature of the container, a first sealing member disposed at one end of the container and having a first through hole, and a second sealing member disposed at the other end of the container and having a second through hole of a different diameter than the first through hole, wherein the first piston slidably passes through the first sealing member, the second piston slidably passes through the second sealing member, and tips of the first piston and second piston are in direct or indirect contact within the container. This makes it possible to realize a thermoelement in which a piston protrudes and retracts with the volume expansion of the volume expansion body, without using a complex electrical control mechanism and with a mechanical mechanism that reduces malfunctions.

[0022] <Configuration of Thermoelement> The configuration of a thermoelement 100 according to an embodiment of the present invention will be described using Fig. 1. Fig. 1 is a cross-sectional view showing the configuration of a thermoelement 100 according to an embodiment of the present invention, and shows the configuration of a packing-type thermoelement.

[0023] As shown in FIG. 1 , a thermo-element 100 according to an embodiment of the present invention includes a spring (low load) 1, a spring (high load) 2, a lid 3, a piston (large diameter) 4, a cover 5, a seal (backup ring) 6, a packing (large diameter) 7, a volume expansion body 8, a housing cup 9, a piston (small diameter) 10, a packing (small diameter) 11, a seal (backup ring) 12, and a cover 13.

[0024] <Explanation of the thermoelement configuration> The thermoelement 100 uses a piston (large diameter) 4 and a piston (small diameter) 10 of different diameters, a high-load spring 2, a low-load spring 1, and a housing cup 9 that penetrates vertically, and autonomously controls the pistons 4 and 10 in response to changes in the ambient temperature, and by combining it with various locking structures, improves the degree of freedom to change the desired amount of protrusion and retraction.

[0025] The spring 1 is a low-load spring that generates a biasing force and is engaged with the housing cup 9. The spring 1 constitutes a second biasing member.

[0026] The spring 2 is a high-load spring, and is engaged with the flange of the piston 4 and the lid 3. The spring 2 constitutes a first biasing member.

[0027] The lid 3 functions as a stopper for the piston 4 .

[0028] The piston 4 is a piston rod made of stainless steel that can be freely protruded and retracted, and constitutes a large-diameter piston serving as a first piston.

[0029] The cover 5 is a lid that serves as a lid for the housing cup 9 .

[0030] The seal 6 is a backup ring.

[0031] The packing 7 is a rubber seal packing (sealing member) for the piston 4. The packing 7 constitutes a first sealing member.

[0032] The volume expansion body 8 is enclosed in a housing cup 9 and expands and contracts in volume in response to changes in the ambient temperature. The volume expansion body 8 changes the volume of the housing cup 9 in response to changes in the ambient temperature, thereby operating the piston (large diameter) 4 and / or the piston (small diameter) 10. The volume expansion body 8 is, for example, a wax such as paraffin wax. In the following, in this embodiment, an example in which wax is used as the volume expansion body 8 will be described.

[0033] The housing cup 9 is a container made of metal such as brass in which a volume expansion body (for example, wax) 8 is sealed.

[0034] The piston 10 is a stainless steel piston rod that can be freely extended and retracted, and constitutes a small-diameter piston serving as a second piston having a different diameter from the piston 4 .

[0035] The packing 11 is a rubber seal packing (sealing member) for the piston 10. The packing 11 constitutes a second sealing member.

[0036] The seal 12 is a backup ring.

[0037] The cover 13 serves as a lid for the housing cup 9 on the piston 10 side.

[0038] The pistons 4 and 10 are configured so that their tips come into direct or indirect contact with each other, and as the temperature around the thermo-element 100 rises, the wax 8 inside the housing cup 9 expands, causing the pistons 4 and 10 to operate autonomously, causing the piston 4 to protrude from the housing cup 9. Of course, the wax enclosed in the housing cup 9 is not limited to paraffin wax, and any substance that has predetermined thermal expansion characteristics with a relatively large change in volume, such as microwax, can be applied to the present invention.

[0039] FIG. 2(a) is a diagram illustrating the operation of the thermoelement in response to changes in ambient temperature shown in FIG. 1, and FIG. 2(b) is a diagram illustrating the state of FIG. 2(a). FIG. 3 is a characteristic diagram showing the relationship between the temperature of the thermoelement shown in FIG. 2(a) and the protrusion / recession amount. FIG. 4 is a characteristic diagram showing the relationship between the temperature of the thermoelement shown in FIG. 2(a) and the wax volume and protrusion / recession amount. Here, the protrusion / recession amount refers to the length of movement of the thermoelement in the protrusion direction (extending direction) or the recession direction (returning direction) from the initial position of the tip of the thermoelement. This protrusion / recession amount is determined by the location where the thermoelement 100 is mounted, and the determined protrusion / recession amount is referred to as the predetermined protrusion / recession amount. The operating range of the piston 4 or piston 10 is also determined, and this determined value is referred to as the predetermined value. The piston 4 or piston 10 cannot operate above the predetermined value.

[0040] The overall operation of the thermo-element according to the embodiment of the present invention will be described below with reference to FIGS. 2(a), 2(b), 3 and 4. FIG.

[0041] As shown in Figure 2(a), when the ambient fluid temperature changes from a low temperature range to a high temperature range, the state of the wax changes. In the temperature ranges between A and B °C, between B and C °C, at C °C, between C and D °C, at D °C, between D and E °C, and above E °C, as shown in Figure 2(b), in the temperature range between A and B °C, the wax is solid and the volume is small. In the temperature range between B and C °C, the wax is partially melted and the volume is small. At C °C, the wax is partially melted and the volume is medium. In the temperature range between C and D °C, the wax is partially melted and the volume is medium. At D °C, the wax is partially melted and the volume is medium. In the temperature range between D and E °C, the wax is partially melted and the volume is large. At temperatures above E °C, the wax is liquid and the volume is largest.

[0042] In a typical thermoelement with one piston, as shown in Figure 4, the wax volume expands as the temperature rises and contracts as the temperature drops, so the protrusion / recession amount changes in a monotonically increasing (decreasing) manner. In Figure 4, the vertical axis represents the wax volume (mm 3 ), and the horizontal axis is temperature (°C).

[0043] For a typical thermoelement with one piston, for example, let's assume that the initial protrusion / recession length Q1 is Q2, Q3, Q4, and Q5, and the monotonically increasing (decreasing) protrusion / recession lengths Q1, Q2, Q3, Q4, and Q5 represent the monotonically increasing (decreasing) change in the protrusion / recession amount, with the thermoelement tip displacing upward as the temperature rises and decreasing as the temperature drops, as shown in Figure 14. In Figure 3, the vertical axis represents the protrusion / recession amount (mm) and the horizontal axis represents temperature (°C). The temperature ranges in Figures 3 and 4 need only satisfy the relationship A<B<C<D<E. These ranges vary depending on the thermoelement's application, so Figure 3 is a conceptual diagram (image) rather than a specific temperature. The same applies to Figures 5(b) through 11(b) described below.

[0044] In the thermoelement of the present invention, as shown in Figure 3, the autonomous operation of the large diameter piston 4 and small diameter piston 10, the action of the high load spring 2 and low load spring 1, and the action of various locking structures cause a predetermined change in the protrusion / recession length due to a volume change accompanying a change in the state of the wax, and even if the wax becomes liquid, a slight volume expansion occurs, resulting in the relationship between the protrusion / recession amount and temperature characteristics shown in Figure 3.

[0045] Figure 5(a) is a detailed explanatory diagram of the operation image in the temperature range between A and B degrees Celsius in Figure 2(a), and Figure 5(b) is a characteristic diagram showing the relationship between the temperature of the thermoelement and the amount of protrusion and depression when operating in the temperature range between A and B degrees Celsius.

[0046] 5(a) shows the state (starting point) in the low temperature range where the tip of the thermoelement is at the protruding / retracting length P1, with the piston 4 (large diameter) being pushed in the direction of sinking into the housing cup 9 by the return load of the spring (high load) 2, and the wax 8 is in its smallest volume because it is in a solid state. Because the piston (large diameter) 4 is being pushed in the direction of sinking into the housing cup 9, the piston (small diameter) 10 is pushed in the direction of protruding from the housing cup 9, and the state is shown where the tip of the thermoelement is at the protruding / retracting length P1.

[0047] Here, the spring (high load) 2 must have a load that can push out the piston (small diameter) 10 and deflect the spring (low load) 1. If the load is low, the piston (large diameter) 4 cannot push the piston (small diameter) 10 in the direction that it protrudes from the housing cup 9, and the piston does not displace.

[0048] 5(b) shows the state in which the wax 8 is solid. Because the wax 8 is solid, its volume is smallest, and the return load of the spring (heavy load) 2 pushes the piston (large diameter) 4 in the direction of sinking into the housing cup 9. As the piston (large diameter) 4 is pushed in the direction of sinking into the housing cup 9, the piston (small diameter) 10 is pushed in the direction of protruding from the housing cup 9.

[0049] Figure 6(a) is a detailed explanatory diagram of the operating image in the temperature range between B and C°C in Figure 2(a), and Figure 6(b) is a characteristic diagram showing the relationship between the temperature between B and C°C and the amount of protrusion and retraction of the tip of the thermo-element.

[0050] 6(a) shows the state in which the tip of the thermo-element is displaced from protruding / retracting length P1 to protruding / retracting length P2 in the temperature range between B and C° C. In the temperature range between B and C° C, the wax 8 partially melts, causing a greater volume expansion than in the temperature range between A and B° C. This generates internal pressure within the housing cup 9, causing the piston (small diameter) 10 and piston (large diameter) 4 to protrude from within the housing cup 9 against the biasing forces of the spring (low load) 1 and spring (high load) 2. The cross-sectional area of ​​the piston (large diameter) 4 and the biasing force generated by the spring (high load) 2 are set so that the force generated by the internal pressure to cause the piston (large diameter) 4 to protrude from the housing cup 9 is greater than the biasing force generated by the spring (high load) 2, and the cross-sectional area of ​​the piston (small diameter) 10 and the biasing force generated by the spring (low load) 1 are set so that the force generated by the internal pressure to cause the piston (small diameter) 10 to protrude from the housing cup 9 is smaller than the biasing force generated by the spring (low load) 1.Therefore, when the tips of the piston (large diameter) 4 and piston (small diameter) 10 are in contact, the piston (large diameter) 4 moves in the direction of protruding from the housing cup 9, and the piston (small diameter) 10 moves in the direction of sinking into the housing cup 9.

[0051] As shown in Figure 6(b), the amount of volumetric expansion of the wax 8 must match the total volume of the piston (large diameter) 4 and piston (small diameter) 10 protruding and retracting from the housing cup 9. Therefore, the piston (large diameter) 4 and piston (small diameter) 10 protrude and retract from the housing cup 9 in accordance with the amount of volumetric expansion of the wax 8 that corresponds to the temperature within the temperature range between B and C degrees Celsius, and the tip of the thermoelement is positioned within a range from protrusion / retraction amount P1 to protrusion / retraction length P2 that corresponds to the temperature within the temperature range between B and C degrees Celsius.

[0052] FIG. 7(a) is a detailed explanatory diagram of the operation image at C°C in FIG. 2(a), and FIG. 7(b) is a characteristic diagram showing the relationship between the temperature at C°C and the tip protrusion / recession length of the thermo-element.

[0053] 7(a) shows the state where the tip of the thermo-element is positioned at protruding / retracting length P2 at C° C. At C° C, the wax 8 melts more than in the temperature range between B and C° C, causing volume expansion, and internal pressure is generated within the housing cup 9 to protrude the piston (small diameter) 10 and the piston (large diameter) 4 from within the housing cup 9 against the biasing forces of the spring (low load) 1 and the spring (high load) 2. The cross-sectional area of ​​the piston (large diameter) 4 and the biasing force generated by the spring (high load) 2 are set so that the force generated by the internal pressure to cause the piston (large diameter) 4 to protrude from the housing cup 9 is greater than the biasing force generated by the spring (high load) 2, and the cross-sectional area of ​​the piston (small diameter) 10 and the biasing force generated by the spring (low load) 1 are set so that the force generated by the internal pressure to cause the piston (small diameter) 10 to protrude from the housing cup 9 is smaller than the biasing force generated by the spring (low load) 1.Therefore, when the tips of the piston (large diameter) 4 and piston (small diameter) 10 are in contact, the piston (large diameter) 4 moves in a direction protruding from the housing cup 9, and the piston (small diameter) 10 tries to move in a direction to sink into the housing cup 9, but a stopper provided on the piston (small diameter) 10 comes into contact with the cover 13, preventing the piston (small diameter) 10 from moving further in a direction to sink into the housing cup 9.

[0054] As shown in FIG. 7(b), the tip of the thermo-element is located within the range of the protruding and retracting length P2.

[0055] Figure 8(a) is a detailed explanatory diagram of the operating image in the temperature range between C and D°C in Figure 2(a), and Figure 8(b) is a characteristic diagram showing the relationship between the temperature in the temperature range between C and D°C and the amount of protrusion and recession of the tip of the thermoelement.

[0056] 8(a) shows the state in which the tip of the thermo-element is at a protruding / retracting length P2 in the temperature range between C and D° C. In the temperature range between C and D° C., the wax 8 partially melts, causing a greater volume expansion than at temperature C, generating internal pressure within the housing cup 9 that attempts to protrude the piston (small diameter) 10 and piston (large diameter) 4 from within the housing cup 9 against the biasing forces of the spring (low load) 1 and spring (high load) 2. The cross-sectional area of ​​the piston (large diameter) 4 and the biasing force generated by the spring (high load) 2 are set so that the force generated by the internal pressure to cause the piston (large diameter) 4 to protrude from the housing cup 9 is greater than the biasing force generated by the spring (high load) 2, and the cross-sectional area of ​​the piston (small diameter) 10 and the biasing force generated by the spring (low load) 1 are set so that the force generated by the internal pressure to cause the piston (small diameter) 10 to protrude from the housing cup 9 is smaller than the biasing force generated by the spring (low load) 1.Furthermore, since the stopper provided on the piston (small diameter) 10 comes into contact with the cover 13 and the piston (small diameter) 10 cannot move in the direction of sinking into the housing cup 9, only the piston (large diameter) 4 moves in the direction of protruding from the housing cup 9.

[0057] 8(b), the piston (small diameter) 10 does not move in the direction of either sinking or protruding into the housing cup 9, so the tip of the thermo-element is located within the range of the protrusion / retraction length P2. The amount of protrusion / retraction of the protrusion / retraction length P2 can be adjusted by adjusting the thickness of the stopper provided on the piston (small diameter) 10.

[0058] FIG. 9(a) is a detailed explanatory diagram of the operation image at D°C in FIG. 2(a), and FIG. 9(b) is a characteristic diagram showing the relationship between the temperature at D°C and the amount of protrusion and retraction of the thermo-element tip.

[0059] 9(a) shows the state where the tip of the thermo-element is positioned at protruding / retracting length P2 at D° C. At D° C, the wax 8 melts more than in the temperature range between C and D° C, causing volume expansion, and internal pressure is generated within the housing cup 9 to protrude the piston (small diameter) 10 and the piston (large diameter) 4 from within the housing cup 9 against the biasing forces of the spring (low load) 1 and the spring (high load) 2. The cross-sectional area of ​​piston (large diameter) 4 and the biasing force generated by spring (high load) 2 are set so that the force generated by the internal pressure to cause piston (large diameter) 4 to protrude from housing cup 9 is greater than the biasing force generated by spring (high load) 2, and the cross-sectional area of ​​piston (small diameter) 10 and the biasing force generated by spring (low load) 1 are set so that the force generated by the internal pressure to cause piston (small diameter) 10 to protrude from housing cup 9 is smaller than the biasing force generated by spring (low load) 1.In addition, the stopper provided on piston (small diameter) 10 contacts cover 13 and prevents piston (small diameter) 10 from moving in the direction of sinking into housing cup 9.Therefore, in the temperature range between C and D degrees Celsius, only piston (large diameter) 4 moves in the direction of protruding from housing cup 9, but at D degrees Celsius, piston (large diameter) 4 contacts lid 3 and cannot move in the direction of protruding from housing cup 9.

[0060] As shown in FIG. 9(b), the tip of the thermo-element is located at a protruding / recessed length P2.

[0061] Figure 10(a) is a detailed explanatory diagram of the operating image in the temperature range between D and E°C in Figure 2(a), and Figure 10(b) is a characteristic diagram showing the relationship between the temperature in the temperature range between D and E°C and the protruding and recessed length of the thermoelement tip.

[0062] 10(a) shows the state in which the tip of the thermoelement is displaced from protruding / retracting length P2 to protruding / retracting length P3 in the temperature range between D and E°C. In the temperature range between D and E°C, wax 8 partially melts, causing a greater volume expansion than at D°C. This generates internal pressure within housing cup 9, forcing piston (small diameter) 10 and piston (large diameter) 4 to protrude from housing cup 9 against the biasing forces of spring (low load) 1 and spring (high load) 2. A force is applied by the internal pressure to protrude piston (large diameter) 4 from housing cup 9, but piston (large diameter) 4 comes into contact with lid 3, preventing piston (large diameter) 4 from moving in the direction of protrusion from housing cup 9. Therefore, piston (small diameter) 10 moves in the direction of protrusion from housing cup 9 by the amount of volume expansion of wax 8 compared to D°C, against the biasing force generated by spring (low load) 1.

[0063] As shown in Figure 10(b), the amount of volumetric expansion of the wax 8 must match the total volume of the piston (large diameter) 4 and piston (small diameter) 10 protruding from and retracted into the housing cup 9. Therefore, in accordance with the amount of volumetric expansion of the wax 8 that corresponds to the temperature within the temperature range between D and E degrees Celsius, the piston (large diameter) 4 protrudes from the housing cup 9 until it comes into contact with the lid 3, and the piston (small diameter) 10 moves in the direction of protruding from the housing cup 9, so that the tip of the thermoelement is positioned within the range of protrusion / retraction length P2 to protrusion / retraction length P3 that corresponds to the temperature within the temperature range between D and E degrees Celsius.

[0064] FIG. 11(a) is a detailed explanatory diagram of the operation image in the temperature range of E°C or higher in FIG. 2(a), and FIG. 11(b) is a characteristic diagram showing the relationship between the temperature in the temperature range of E°C or higher and the protruding and recessed length of the thermo-element tip.

[0065] 11(a) shows that in the temperature range of E°C or higher, all of the wax 8 melts, causing a greater volume expansion than in the temperature range between D and E°C, and internal pressure is generated within the housing cup 9 in an attempt to protrude the piston (small diameter) 10 and the piston (large diameter) 4 from within the housing cup 9 against the biasing forces of the spring (low load) 1 and the spring (high load) 2. A force is applied by the internal pressure to protrude the piston (large diameter) 4 from the housing cup 9, but the piston (large diameter) 4 comes into contact with the lid 3 and is unable to move in the direction protruding from the housing cup 9, and the piston (small diameter) 10 moves in the direction protruding from the housing cup 9 by an amount equal to the volume expansion of the wax 8 compared to that at D°C, against the biasing force generated by the spring (low load) 1.

[0066] 11(b), the amount of volumetric expansion of the wax 8 must match the total volume of the piston (large diameter) 4 and piston (small diameter) 10 protruding from and retracting into the housing cup 9, so that the piston (large diameter) 4 protrudes from the housing cup 9 until it contacts the lid 3 in accordance with the amount of volumetric expansion of the wax 8 corresponding to the temperature in the temperature range between D and E°C, and the piston (small diameter) 10 moves in the direction of protruding from the housing cup 9, thereby positioning the tip of the thermoelement at a protrusion / retraction length of P3 or more corresponding to the temperature in the temperature range above E°C. Note that the liquid phase volume expansion coefficient of the wax 8 in the temperature range above E°C is smaller than the melt volume expansion coefficient in the temperature range between D and E°C, so the displacement gradient with respect to temperature at the tip of the thermoelement in the temperature range above E°C is smaller than that in the temperature range between D and E°C.

[0067] Figure 12 shows an image of the use of a thermoactuator to which the present invention is applied, where (a) shows when the coolant temperature is low, (b) shows when the coolant temperature is medium, and (c) shows when the coolant temperature is high. In Figures 12(a), (b), and (c), the thick arrows indicate the flow of exhaust gas, and the dashed arrows indicate the flow of coolant.

[0068] 12(a), 12(b), and 12(c), by using the thermoelement 120 of the present invention, as the temperature of the cooling water increases, the valve 122 in the flow path through which the exhaust gas flows to the heat exchanger 121 can be changed from open to closed to open. The thermoelement 120 of the present invention has the same configuration as that shown in FIG. 1 or 13, and therefore will not be described here.

[0069] Fig. 13 is a cross-sectional view showing the configuration of a thermoelement according to another embodiment of the present invention. The thermoelement 200 shown in Fig. 13 shows a sleeve-type thermoelement configuration, and since the configuration other than the configuration of the sleeve 14 and the seals 6' and 12' is the same as that of the thermoelement in Fig. 1, a description thereof will be omitted and only the different configuration will be described.

[0070] The first and second sealing members are integrally configured to form the sealing member, and the first piston and the second piston are configured to come into direct or indirect contact with each other within the through-hole of the sealing member. With the sleeve-type configuration, the piston is protected by the sleeve, which improves reliability compared to a packing type that does not have a sleeve.

[0071] As described above, the thermoelements of this embodiment and other embodiments do not utilize heater heat, eliminating the risk of inoperability due to heat loss and enabling operation in low-temperature environments. While water and aqueous solutions have the drawback of being unable to select a melting point and having a low expansion coefficient, the use of paraffin wax allows operation at any temperature and has a high expansion coefficient, making them superior to the thermoelement of Japanese Patent No. 6,399,585, which uses two types of thermal expansion bodies. Instead of a complex electrical control mechanism, wax is simply sealed inside the pellet of an existing configuration, reducing the number of parts and lowering manufacturing costs. Because no electrical control mechanism is required, the thermoelement is smaller and parts cost is lower than conventional electrical thermoactuators. Since assembly of the electrical control mechanism is not required, productivity is improved. In addition to the normal thermostat operation, the thermoelement is re-operable, allowing it to operate in other fields by opening the valve at extremely low temperatures, closing it at room temperature, and opening it at high temperatures (or closing the valve at low temperatures, opening at room temperature, and closing at high temperatures). Because it operates autonomously, there is no need for wiring or drive control devices on the vehicle side.

[0072] Although the thermoelement according to the embodiment of the present invention has been described in detail above, the above-described and illustrated embodiments are merely specific examples of the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these embodiments. In particular, the materials of each component are merely examples, and it goes without saying that they can be appropriately changed to other materials having equivalent strength.

[0073] 100, 200: Thermoelement 1: Spring (second biasing member) 2: Spring (first biasing member) 3: Lid 4: Piston (first piston) 5: Cover (large diameter) 6: Seal (backup ring) 6': Seal (backup ring) 7: Packing (sealing member) 8: Volume expansion body 9: Housing cup 10: Piston (second piston) 11: Packing (sealing member) 12: Seal (backup ring) 12': Seal (backup ring) 13: Cover (small diameter) 14: Sleeve (sealing member) 120: Thermoelement 121: Heat exchanger 122: Valve

Claims

1. A thermo-element, comprising: a container; a volume expander accommodated in the container and expanding or contracting in volume due to a change in ambient temperature; a first piston actuated by a volume change of the volume expander due to a change in ambient temperature of the container; a second piston having a different diameter from the first piston and actuated by a volume change of the volume expander due to a change in ambient temperature of the container; a first sealing member disposed at one end of the container and having a first through-hole; and a second sealing member disposed at the other end of the container and having a second through-hole with a different diameter from the first through-hole, wherein the first piston slidably penetrates the first sealing member, the second piston slidably penetrates the second sealing member, and the tips of the first piston and the second piston are configured to be in direct or indirect contact with each other inside the container.

2. The thermo-element according to claim 1, wherein a first biasing force by a first biasing member and a second biasing force by a second biasing member are configured to bias the first piston and the second piston in the retracting direction, respectively, and the magnitude of the first biasing force is configured to be greater than that of the second biasing force.

3. The thermoelement according to claim 2, wherein the relationship between the first biasing force and the second biasing force is configured to satisfy the following relational expression (1).

4. The thermo-element according to claim 3, further comprising a locking structure configured to stop the first piston at a predetermined protrusion / retraction amount even when the ambient temperature rises.

5. The thermo-element according to claim 4, wherein a stopper is configured on the first piston so that the first piston does not enter the container by more than a predetermined value.

6. The thermo-element according to claim 5, wherein the first sealing member and the second sealing member integrally form a sealing member, and the first piston and the second piston are configured to be in direct or indirect contact with each other inside the through-hole of the sealing member.

7. The thermo-element according to claim 5 or 6, wherein the second piston has a cover provided with a stopper mechanism so that the second piston does not sink to a predetermined protrusion / retraction amount.

8. The thermo-element according to claim 5 or 6, wherein the second piston is provided with a stopper mechanism so that the second piston does not sink to a predetermined protrusion / retraction amount.

9. The thermoelement according to claim 5 or 6, further comprising a lid that is movable integrally with the container on the side of the first piston, wherein the stopper and the lid are configured such that the first biasing member is locked thereto.

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