JP7469967B2 - Thermoelectric power generation device - Google Patents

Description

The present invention relates to a thermoelectric power generation device.

Patent document 1 discloses a thermoelectric power generation device that generates electromotive force due to the temperature difference between a high-temperature side and a low-temperature side. The thermoelectric power generation device of Patent document 1 includes a thermoelectric conversion element that generates electromotive force due to the temperature difference between one end of the high-temperature side and the other end of the low-temperature side, and a sealing member that seals the thermoelectric conversion element.

The sealing member is composed of a first member and a second member. The first member of the sealing member has an abutment member that faces one end of the thermoelectric conversion element. A thermally conductive member is provided between the other end of the thermoelectric conversion element and the second member of the sealing member, and the thermally conductive member is cooled by the cooling means via the second member. By providing a thermally conductive member inside the sealing member, it is possible to ensure a certain degree of thickness of the sealing member, and to mitigate the effect of thermal deformation of the sealing member on heat transfer between each member.

JP 2018-10908 A

The components that generate heat conduction between the thermoelectric conversion element, such as the first member, second member, and heat-conducting member disclosed in Patent Document 1, are generally made of metals that have excellent thermal conductivity while taking into consideration weight and cost.

When different metal materials are used for each component of a thermoelectric power generation device, there is a risk of electrical corrosion occurring between the components made of different materials when they come into contact with each other. This electrical corrosion may reduce the durability of the thermoelectric power generation device.

The present invention was made in consideration of the above problems, and aims to improve the durability of thermoelectric power generation devices.

The present invention is a thermoelectric power generation device comprising a first member and a second member made of different metals, a thermoelectric conversion element thermally connected to each of the first member and the second member and converting the temperature difference between the first member and the second member into electric power, a first heat conduction member provided on the first member and supporting the thermoelectric conversion element, and a second heat conduction member provided on the second member and supporting the thermoelectric conversion element together with the first heat conduction member, wherein the first heat conduction member is made of the same metal as the first member and the second heat conduction member is made of the same metal as the second member, and the first heat conduction member and the second heat conduction member are formed in a rod shape and support the thermoelectric conversion element at their respective ends .

In this invention, the heat conductive member is made of the same material as the first member when attached to the first member, and is made of the same material as the second member when attached to the second member, thereby suppressing the occurrence of electrolytic corrosion between the heat conductive member and the first and second members.

The present invention is also characterized in that the first member is attached to a heat source, the second member is configured as a heat sink for dissipating heat from the second member to the atmosphere, the second member and the second heat conduction member are formed of a material having a higher thermal conductivity than the first heat conduction member, and the length of the second heat conduction member is longer than the length of the first heat conduction member.

The present invention is also characterized in that the first member and the first heat conduction member are formed of steel, the second member and the second heat conduction member are formed of an aluminum-based or copper-based material, the first member is attached to a heat source, the second member is configured as a heat sink for dissipating heat from the second member to the atmosphere , and the length of the second heat conduction member is longer than the length of the first heat conduction member.

In these inventions , the power generation efficiency of the thermal power generation device can be increased by configuring the second heat conductive member, which has a higher thermal conductivity than the first heat conductive member, to be long.

The present invention is also characterized in that it includes a resin insulating member that is formed into a cylindrical shape and sandwiched between a first member and a second member, and the first member and the second member are connected to each other via the insulating member.

In this invention, the first and second members are insulated from each other by the insulating member, and direct contact between the two members is avoided, preventing the occurrence of electrolytic corrosion.

The present invention further comprises a first screw member provided on one of the first member and the second member and having a female thread formed thereon, and a second screw member made of resin having a male thread formed thereon that screws into the female thread of the first screw portion and connects the first member and the second member by inserting the other of the first member and the second member and screwing into the first screw member, and is characterized in that a gap is formed between the first screw member and the other of the first member and the second member, so that they are separated from each other without contacting each other.

In this invention, the first member and the second member are connected by a resin screw made of resin, so that the occurrence of electrolytic corrosion caused by using a metal screw member is prevented. In addition, the occurrence of electrolytic corrosion caused by contact between the connecting member and the other of the first member and the second member is prevented.

The present invention improves the durability of the thermoelectric power generation device.

1 is a partial cross-sectional view of a hydraulic cylinder to which a thermoelectric power generating device according to an embodiment of the present invention is attached. 2 is a partially enlarged cross-sectional view of a hydraulic cylinder to which a thermoelectric power generating device according to an embodiment of the present invention is attached. FIG. 3 is a plan view of a heat dissipation member of a thermoelectric power generating device according to an embodiment of the present invention. FIG. 3 is a plan view of a spacer of a thermoelectric power generating device according to an embodiment of the present invention. FIG. 1A and 1B are cross-sectional views for explaining a method for manufacturing a thermoelectric power generating device according to an embodiment of the present invention, showing a state in which a heat dissipation member and a spacer are assembled. FIG. 11 is a cross-sectional view showing a thermoelectric power generating device according to a modified example of an embodiment of the present invention.

The following describes a thermoelectric power generation device 100 according to an embodiment of the present invention with reference to the drawings.

The thermoelectric power generation device 100 is used, for example, as a power source for a sensor device 101 installed in the fluid pressure system of a construction machine (such as a hydraulic excavator).

First, referring to FIG. 1, we will explain the sensor device 101 to which the thermal power generation device 100 is applied.

The following describes the case where the sensor device 101 is an oil leak sensor that detects hydraulic oil leakage that occurs in a hydraulic cylinder 1 (fluid pressure cylinder) of a fluid pressure system that drives a drive object (not shown) such as a boom, arm, and bucket.

As shown in FIG. 1, the hydraulic cylinder 1 comprises a cylindrical cylinder tube 2, a piston rod 3 inserted into the cylinder tube 2, and a piston 4 provided at the base end of the piston rod 3. The piston 4 is provided so as to be able to slide freely along the inner circumferential surface of the cylinder tube 2. The inside of the cylinder tube 2 is divided by the piston 4 into a rod side chamber 2a and an anti-rod side chamber 2b.

The tip of the piston rod 3 extends from the open end of the cylinder tube 2. When hydraulic oil is selectively introduced from a hydraulic source (not shown) into the rod side chamber 2a or the anti-rod side chamber 2b, the piston rod 3 moves relative to the cylinder tube 2. This causes the hydraulic cylinder 1 to expand and contract.

A cylinder head 5 through which the piston rod 3 is inserted is provided at the open end of the cylinder tube 2. The cylinder head 5 is fastened to the open end of the cylinder tube 2 using a number of bolts 6. The cylinder tube 2 and the cylinder head 5 are made of an iron-based material, specifically, steel.

As shown in FIG. 2, the cylinder head 5 is provided with a rod seal 7a that seals the annular gap (hereinafter referred to as the "annular gap 8") between the outer peripheral surface of the piston rod 3 and the inner peripheral surface of the cylinder head 5, a detection seal 7b that seals the annular gap 8 and defines a detection space 9 together with the rod seal 7a, a bush 7c that slidably supports the piston rod 3, and a dust seal 7d that scrapes off dust adhering to the outer peripheral surface of the piston rod 3 and prevents dust from entering the cylinder tube 2 from the outside.

The sensor device 101 is attached to the outer periphery of the cylinder head 5 of the hydraulic cylinder 1, and detects the pressure of the hydraulic oil leaking from the annular gap 8 between the outer periphery of the piston rod 3 and the inner periphery of the cylinder head 5. The detection result of the sensor device 101 is transmitted to the controller 102 by wireless communication. The controller 102 determines the presence or absence of oil leakage in the hydraulic cylinder 1 based on the detection result of the sensor device 101.

The sensor device 101 includes a thermoelectric generator 100 that generates electricity using the temperature difference between the housing 20 as a first member and the heat dissipation member 30 as a second member, a pressure sensor 80 as a sensor unit that detects the pressure of hydraulic oil leaking from the rod side chamber 2a of the hydraulic cylinder 1 into the annular gap 8, and a circuit board 81 to which the thermoelectric generator 100 and the pressure sensor 80 are electrically connected via wiring 16, 82, respectively. The circuit board 81 is equipped with a power supply circuit that supplies the power generated by the thermoelectric generator 100 to the pressure sensor 80, and a communication circuit that wirelessly transmits the detection result of the pressure sensor 80 to the controller 102.

The thermoelectric power generation device 100 comprises a case 10 and a thermoelectric conversion element (hereinafter simply referred to as "thermoelectric element 15") that is housed in the case 10 and generates an electromotive force in response to the temperature difference between the heat absorption surface 15a and the heat dissipation surface 15b.

The case 10 has a housing 20 attached to the cylinder head 5 of the hydraulic cylinder 1, a heat dissipation member 30 configured as a heat sink with multiple fins 31a on its outer periphery, and a spacer 40 as a resin insulating member that is sandwiched between the housing 20 and the heat dissipation member 30 and surrounds the thermoelectric element 15.

The housing 20 is made of the same iron-based material (more specifically, steel) as the cylinder head 5 of the hydraulic cylinder 1, and is attached to the cylinder head 5. By making the housing 20 out of steel, the durability of the housing 20 (and thus the case 10) is ensured, and the occurrence of electrolytic corrosion between the housing 20 and the cylinder head 5 to which it is attached can be prevented. Heat generated in the hydraulic cylinder 1, which is the heat source, is transferred to the housing 20 through the cylinder head 5.

The housing 20 is formed with an accommodating recess 21 that opens on the end face and accommodates the thermoelectric element 15, a sensor accommodating hole 22 that opens into the accommodating recess 21 and accommodates the pressure sensor 80, and a communication passage 23 that opens into the abutment surface of the housing 20 that abuts against the cylinder head 5 of the hydraulic cylinder 1 and also opens into the sensor accommodating hole 22. The communication passage 23 communicates with the detection space 9 through a head-side passage 9a formed in the cylinder head 5 of the hydraulic cylinder 1. As a result, the pressure of the hydraulic oil that has leaked into the detection space 9 through the annular gap 8 is guided to the sensor accommodating hole 22 through the head-side passage 9a and the communication passage 23, and the pressure is detected by the pressure sensor 80.

The housing 20 is fitted with a first heat conducting member 50 as a heat conducting member that transfers heat from the housing 20 to the heat absorbing surface 15a of the thermoelectric element 15. The first heat conducting member 50 is a cylindrical rod-shaped member made of the same material as the housing 20 (steel in this embodiment), and one end is attached to the bottom of the housing recess 21 of the housing 20 by a mounting bolt 70. The mounting bolt 70 is a stud bolt (fully threaded bolt) with threads formed at both ends, and both ends are screwed into the bottom of the housing recess 21 and the female threads formed on one end face of the first heat conducting member 50, respectively. The thermoelectric element 15 is attached to the other end (tip) of the first heat conducting member 50 by an adhesive 55. The adhesive 55 is a liquid adhesive with excellent thermal conductivity. The adhesive 55 is not limited to a liquid adhesive, and may be a solid adhesive or a sheet-like adhesive tape.

The heat dissipation member 30 is made of a material with excellent thermal conductivity, such as an aluminum-based or copper-based material. In this way, the heat dissipation member 30 is made of a metal different from the housing 20, which is made of steel, and has better thermal conductivity than the housing 20.

The heat dissipation member 30 is formed in a cylindrical shape with one end closed. A plurality of annular fins 31a are arranged in the axial direction on the outer periphery of the heat dissipation member 30. A boss portion 32 is provided at the bottom of the heat dissipation member 30, protruding in the axial direction toward the outside of the heat dissipation member 30.

As shown in Figures 2 and 3, a slit 32b through which the circuit board 81 is inserted is formed in the bottom of the heat dissipation member 30. A part of the circuit board 81 protrudes from the storage space S1 inside the housing 20 and spacer 40 described below through the slit 32b into the inner space S2 of the heat dissipation member 30. Note that Figure 3 is a plan view of the heat dissipation member 30 as viewed from the direction of the arrow A in Figure 2.

The inner space S2 of the heat dissipation member 30 is potted and sealed with molded resin 35 together with a part of the circuit board 81 and the head of a resin screw 72 described later. In this way, the circuit board 81 is not entirely housed inside the metal housing 20 or heat dissipation member 30, but a part of it protrudes outside the storage space S1 inside the housing 20, specifically into the inner space S2 of the heat dissipation member 30 facing (exposed) to the outside of the thermal power generation device 100. This allows wireless communication to be stably performed by the communication means provided on the circuit board 81. The inner space S2 of the heat dissipation member 30 is sealed with molded resin 35, but since resin is less likely to interfere with communication radio waves than metal, sealing with molded resin 35 can sufficiently stabilize wireless communication. The molded resin 35 is not an essential component, and the inner space S2 does not have to be potted.

A second heat conducting member 51 is attached to the heat dissipation member 30 as a heat conducting member that transfers heat from the heat dissipation surface 15b of the thermoelectric element 15 to the heat dissipation member 30. The second heat conducting member 51 is a cylindrical rod-shaped member made of the same material as the heat dissipation member 30 and has approximately the same diameter as the first heat conducting member 50. The second heat conducting member 51 has an attachment bolt 71 inserted into one end and is attached to the tip surface 32a of the boss portion 32 of the heat dissipation member 30 by the attachment bolt 71. The attachment bolt 71 is inserted through the insertion hole 30a at the bottom of the heat dissipation member 30 and screwed into the female thread provided at one end of the second heat conducting member 51. The thermoelectric element 15 is attached to the other end (tip) of the second heat conducting member 51 by adhesive 55.

In this way, the thermoelectric element 15 is sandwiched (supported) between the first heat conducting member 50 attached to the housing 20 and the second heat conducting member 51 attached to the heat dissipation member 30.

The spacer 40 is made of a resin material with high thermal insulation properties. The spacer 40 has a through hole 40a along the central axis at its radial center, and is formed in a cylindrical shape to surround the thermoelectric element 15. The spacer 40 is sandwiched between the housing 20 and the heat dissipation member 30, and is connected to the housing 20 and the heat dissipation member 30 by an adhesive (not shown). The spacer 40 has a main body portion 41 whose outer peripheral surface is formed in a tapered shape, and an insertion portion 42 that is inserted into the accommodation recess 21 of the housing 20.

The outer periphery of the main body 41 is tapered so that the outer diameter increases as it moves away from the housing 20 along the axial direction of the spacer 40, in other words, from the housing 20 toward the heat dissipation member 30. The insertion portion 42 is formed so as to protrude axially from the end of the main body 41 toward the housing 20. The outer diameter of the insertion portion 42 is smaller than the outer diameter of the end of the main body 41 (the minimum outer diameter of the main body 41), and a step surface formed by the difference in outer diameter between the insertion portion 42 and the main body 41 abuts against the end face of the housing 20.

The storage recess 21 of the housing 20 and the through hole 40a of the spacer 40 form a storage space S1 that stores the thermoelectric element 15. As shown in FIG. 4, the inner peripheral surface of the spacer 40 is formed with axially extending slits 40b into which both edges of the circuit board 81 are inserted to support the circuit board 81. Note that FIG. 4 is a plan view of the spacer 40 as viewed from the direction of the arrow A in FIG. 2. Also, in FIG. 4, the circuit board 81 is shown diagrammatically by a two-dot chain line.

The inner circumferential surface of the through hole 40a of the spacer 40 is formed with an axially extending accommodation groove 40c into which the first heat conducting member 50 and the second heat conducting member 51 are inserted. The accommodation groove 40c has a substantially semicircular cross section that matches the outer shape of the first heat conducting member 50 and the second heat conducting member 51. The accommodation groove 40c, the first heat conducting member 50, and the second heat conducting member 51 are provided at positions offset from the center of the accommodation recess 21 of the housing 20 (see Figures 2 and 4). The accommodation groove 40c serves to circumferentially align the first heat conducting member 50 and the second heat conducting member 51 when assembling the thermal power generation device 100 and the sensor device 101.

As shown in FIG. 2, the boss portion 32 of the heat dissipation member 30 is inserted into the through hole 40a of the spacer 40 from the side opposite the housing 20. As a result, one opening of the through hole 40a of the spacer 40 is blocked by the heat dissipation member 30. In other words, the storage space S1 formed by the storage recess 21 of the housing 20 and the through hole 40a of the spacer 40 is blocked by the heat dissipation member 30.

The housing 20 and the heat dissipation member 30 are connected to each other via the spacer 40, and are not in direct contact with each other. Therefore, the spacer 40 suppresses heat conduction between the housing 20 and the heat dissipation member 30. Furthermore, the resin spacer 40 prevents direct contact between the housing 20 and the heat dissipation member 30, which are made of different materials, and therefore prevents the occurrence of electrolytic corrosion due to contact between the housing 20 and the heat dissipation member 30.

In this way, the spacer 40 not only functions as a spacer that prevents direct contact between the housing 20 and the heat dissipation member 30, but also functions as a heat insulating member that suppresses heat conduction between the housing 20 and the heat dissipation member 30. Furthermore, the spacer 40 is provided to surround the thermoelectric element 15, and together with the housing 20 forms the accommodation space S1 that accommodates the thermoelectric element 15. As a result, the spacer 40 suppresses temperature changes in the accommodation space S1 due to the influence of the outside air, specifically, temperature changes in the first heat conduction member 50 and the second heat conduction member 51.

The housing 20 and the heat dissipation member 30 are connected to each other by a connecting member 52 as a first screw member provided on the housing 20 and having a female thread at its tip, and a resin screw 72 as a second screw member made of resin and having a male thread that passes through the heat dissipation member 30 and screws into the female thread of the connecting member 52. In other words, the housing 20 and the connecting member 52 are connected via the spacer 40, and are also connected by the connecting member 52 and the resin screw 72.

The connecting member 52 is a cylindrical member made of the same material (steel) as the housing 20, and one end is attached to the bottom of the accommodation recess 21 of the housing 20. By making the connecting member 52 attached to the housing 20 out of the same material as the housing 20, the occurrence of electrolytic corrosion between the housing 20 and the connecting member 52 is prevented.

The connecting member 52, like the first heat conduction member 50, is attached to the housing 20 by a mounting bolt 73 such as a stud bolt that screws into both the bottom of the accommodating recess 21 and the connecting member 52. The other end of the connecting member 52 is separated from the tip surface 32a of the boss portion 32 of the heat dissipation member 30 without contacting it. In other words, in the axial direction of the connecting member 52, a gap is formed between the tip of the connecting member 52 and the heat dissipation member 30, and the connecting member 52 and the heat dissipation member 30 are configured not to come into contact with each other. Although detailed illustration is omitted, in this embodiment, three connecting members 52 are attached to the housing 20.

The resin screw 72 is made of a resin material with excellent heat insulating properties. The resin screw 72 is inserted through an insertion hole 32c formed in the bottom (boss portion 32) of the heat dissipation member 30 and screwed into the connecting member 52. Three insertion holes 32c are formed in the bottom of the heat dissipation member 30 corresponding to the connecting members 52 (see FIG. 3). The housing 20 and the heat dissipation member 30 are screwed together by tightening the resin screw 72 with a predetermined tightening force. Note that even when the resin screw 72 is tightened with a predetermined tightening force, a gap exists between the connecting member 52 and the bottom of the heat dissipation member 30.

The thermoelectric element 15 is a Seebeck element that has a heat absorption surface 15a and a heat dissipation surface 15b that are a pair of parallel flat surfaces, and generates an electromotive force due to the temperature difference between the heat absorption surface 15a and the heat dissipation surface 15b. The thermoelectric element 15 has the heat absorption surface 15a bonded to the tip surface of the first heat conduction member 50 by adhesive 55, and the heat dissipation surface 15b bonded to the tip surface of the second heat conduction member 51. In this way, the heat absorption surface 15a is thermally connected to the housing 20 through the first heat conduction member 50. Also, the heat dissipation surface 15b is thermally connected to the heat dissipation member 30 through the second heat conduction member 51. It is desirable to use an adhesive 55 with excellent thermal conductivity.

The thermoelectric element 15 absorbs heat on the heat absorption surface 15a and dissipates heat from the heat dissipation surface 15b, which generates a temperature difference inside and generates an electromotive force. In other words, the thermoelectric element 15 generates an electromotive force according to the difference between the temperature of the housing 20 transferred to the heat absorption surface 15a through the first heat conductive member 50 and the temperature of the heat dissipation member 30 transferred to the heat dissipation surface 15b through the second heat conductive member 51. The electromotive force of the thermoelectric element 15 is supplied to the circuit board 81 connected through the wiring 16.

As described above, in the thermal power generation device 100, heat generated in the hydraulic cylinder 1 is absorbed from the housing 20 through the first heat conductive member 50 to the heat absorption surface 15a of the thermoelectric element 15. The heat absorbed by the heat absorption surface 15a of the thermoelectric element 15 is dissipated from the heat dissipation surface 15b through the second heat conductive member 51 and the heat dissipation member 30 into the atmosphere, generating electricity by the thermoelectric element 15. The power generated by the thermoelectric element 15 of the thermal power generation device 100 is supplied to the circuit board 81, which drives the pressure sensor 80 and the communication circuit. In this way, the sensor device 101 can be driven independently without receiving power supply from the outside by including the thermal power generation device 100 that generates electricity using heat generated in the hydraulic cylinder 1, which is the sensing target. Therefore, there is no need to route wiring for supplying power to the sensor device 101 around the sensor device 101 and the hydraulic cylinder 1, making it easy to install the sensor device 101.

The axial length L1 of the first heat conduction member 50 attached to the housing 20 is shorter than the axial length L2 of the second heat conduction member 51 attached to the heat dissipation member 30. As described above, the first heat conduction member 50 and the second heat conduction member 51 are formed into cylindrical shapes of approximately the same diameter. By configuring the second heat conduction member 51, which has relatively excellent thermal conductivity, to be longer than the first heat conduction member 50, the power generation efficiency of the thermal power generation device 100 can be improved.

Next, we will explain the manufacturing method of the sensor device 101.

In this embodiment, the heat dissipation member 30, the spacer 40, the thermoelectric element 15, the circuit board 81, and the pressure sensor 80 are assembled, and the assembly is attached to the housing 20 to manufacture the sensor device 101. A detailed description is given below.

First, the second heat conducting member 51 is attached to the heat dissipation member 30 using the mounting bolts 71.

Next, the heat dissipation member 30 and the spacer 40 are assembled. Specifically, the second heat conduction member 51 is inserted into the receiving groove 40c on the inner circumference of the spacer 40 while the boss portion 32 of the heat dissipation member 30 is inserted into the through hole 40a of the spacer 40, and the heat dissipation member 30 and the spacer 40 are bonded together with an adhesive.

Next, the pressure sensor 80 and the thermoelectric element 15 are connected to the circuit board 81 by the wiring 16, 82. Furthermore, the circuit board 81 is inserted from the opening of the spacer 40 into the slit 40b (see FIG. 4) on the inner circumferential surface, and passed through the slit 32b (see FIG. 3) formed in the boss portion 32 of the heat dissipation member 30, with a portion of it protruding into the inner space S2 of the heat dissipation member 30. In this manner, an assembly including the heat dissipation member 30 is constructed.

Next, adhesive 55 is applied to the tip of the second heat conducting member 51. At this time, as shown in FIG. 5, for example, the central axis of the heat dissipation member 30 extends substantially horizontally, and the second heat conducting member 51 attached to the heat dissipation member 30 is positioned vertically below the central axis of the heat dissipation member 30, and the adhesive 55 is applied to the tip of the second heat conducting member 51 in such a position. In FIG. 5, the lower side in the figure indicates the vertically downward direction, and the left and right directions indicate the horizontal direction. In this way, the space C formed by the tip of the second heat conducting member 51 and the accommodation groove 40c on the inner circumference of the spacer 40 functions as a pocket for storing the adhesive 55, so that the adhesive 55 can be prevented from dripping from the tip of the second heat conducting member 51. Then, the thermoelectric element 15 is pressed against the adhesive 55 attached to the tip of the second heat conducting member 51 in this way, and the adhesive 55 is cured after a predetermined time has elapsed. As a result, the thermoelectric element 15 is attached to the tip of the second heat conducting member 51.

Next, the first heat transfer member 50 is attached to the bottom of the housing 20 with the mounting bolts 70, and the connecting member 52 is attached to the bottom of the housing 20 with the mounting bolts 73.

Next, the assembly including the heat dissipation member 30 is assembled with the housing 20. Specifically, first, adhesive 55 is applied to the tip of the first heat conductive member 50. Then, the spacer 40 is inserted into the housing recess 21 of the housing 20 so as to align the positions of the first heat conductive member 50 and the housing groove 40c (see Figures 4 and 5) on the inner circumference of the spacer 40. Furthermore, the thermoelectric element 15 attached to the tip of the second heat conductive member 51 is pressed against the adhesive 55 applied to the tip of the first heat conductive member 50, and the thermoelectric element 15 is bonded to the tip of the first heat conductive member 50. In addition, as the spacer 40 is inserted into the housing recess 21 of the housing 20, the pressure sensor 80 is accommodated in the sensor accommodation hole 22 at the bottom of the housing 20 and attached to the housing 20. Furthermore, adhesive is also applied between the spacer 40 and the housing 20, and the two are fixed by the adhesive.

Next, the resin screw 72 is inserted into the through hole 32c of the boss portion 32 from inside the heat dissipation member 30 and screwed into the connecting member 52 to fasten it with a predetermined tightening force. Then, the inner space S2 of the heat dissipation member 30 is filled with the molded resin 35.

The above steps complete the assembly of the sensor device 101 shown in Figure 2.

The assembly of the sensor device 101 is not limited to the order described above, and the order may be changed as far as possible. In addition, each process may be performed simultaneously as far as possible. For example, it is cumbersome to connect the thermoelectric element 15 and the pressure sensor 80 to the circuit board 81 while adhering the thermoelectric element 15 to the first heat conductive member 50 of the housing 20 and attaching the pressure sensor 80 to the housing 20. For this reason, in order to efficiently assemble the sensor device 101, it is desirable to connect the thermoelectric element 15, the pressure sensor 80, and the circuit board 81 in advance as described above to form an assembly, and then attach the assembly to the heat dissipation member 30 (and the spacer 40).

The above embodiment provides the following advantages:

In the thermal power generation device 100, the first heat conduction member 50 attached to the housing 20 is made of steel, which is the same material as the housing 20, and the second heat conduction member 51 attached to the heat dissipation member 30 is made of an aluminum-based or copper-based material, which is the same material as the heat dissipation member 30. This makes it possible to prevent the occurrence of electrical corrosion between the housing 20 and the first heat conduction member 50, and between the heat dissipation member 30 and the second heat conduction member 51. This makes it possible to improve the durability of the thermal power generation device 100.

In addition, the housing 20 and the heat dissipation member 30 are connected to each other via a spacer 40 and do not come into direct contact with each other. This makes it possible to prevent electrolytic corrosion caused by contact between the housing 20 and the heat dissipation member 30.

The housing 20 and the heat dissipation member 30 are fastened together by a connecting member 52 provided on the housing 20 and a resin screw 72 that passes through the heat dissipation member 30. Because the resin screw 72 is made of resin rather than metal, the occurrence of electrolytic corrosion between the connecting member 52 and the resin screw 72 can be prevented.

In addition, the connecting member 52 and the heat dissipation member 30 do not come into contact with each other, and a gap is formed between them. This suppresses heat conduction between the housing 20 and the heat dissipation member 30 through the connecting member 52, and prevents the occurrence of electrolytic corrosion between the connecting member 52 and the heat dissipation member 30.

The housing 20 attached to the cylinder head 5 of the hydraulic cylinder 1 and the first heat conduction member 50 attached to the housing 20 are made of steel, which is the same material as the cylinder head 5. The heat dissipation member 30 and the second heat conduction member 51 are made of an aluminum-based or copper-based material that has excellent thermal conductivity. The second heat conduction member 51 is longer than the first heat conduction member 50. In this way, by configuring the second heat conduction member 51, which has relatively excellent thermal conductivity, to be longer than the first heat conduction member 50, the power generation efficiency of the thermal power generation device 100 can be improved.

Next, modified examples of this embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the configuration shown in the modified example with the configuration described in the above embodiment, or to combine the configurations described in the different modified examples below.

The heat conducting members (first heat conducting member 50, second heat conducting member 51) refer to members that are formed separately from the housing 20 or heat dissipation member 30 and are attached to the housing 20 or heat dissipation member 30, and do not include a form in which the heat conducting members are formed integrally with the housing 20 or heat dissipation member 30 (in other words, the heat conducting members are part of the housing 20 or heat dissipation member 30).

In addition, it is not essential that both the first heat conducting member 50 and the second heat conducting member 51 are provided; it is sufficient that at least one of them is provided. For example, in the modified example shown in FIG. 6, the thermoelectric power generating device 100 includes the second heat conducting member 51 but does not include the first heat conducting member 50 as in the above embodiment, and the thermoelectric element 15 is directly attached to the housing 20 by adhesive 55. Although not shown in the figures, the thermoelectric power generating device 100 may include the first heat conducting member 50 but not the second heat conducting member 51.

In addition, the connecting member 52 and the plastic screw 72 are not essential components, and other means may be used to connect the housing 20 and the heat dissipation member 30.

In addition, in the above embodiment, the thermoelectric power generation device 100 is used in a sensor device 101 that detects oil leakage occurring in the hydraulic cylinder 1. In contrast, the thermoelectric power generation device 100 is not limited to being used as a sensor device 101, and may be used in other devices.

The configuration, operation, and effects of the embodiment of the present invention are summarized below.

The thermoelectric power generation device 100 comprises a housing 20 and a heat dissipation member 30 made of different metals, a thermoelectric element 15 that is thermally connected to each of the housing 20 and the heat dissipation member 30 and generates an electromotive force in response to the temperature difference between the housing 20 and the heat dissipation member 30, and a heat conduction member (first heat conduction member 50, second heat conduction member 51) that is provided on one of the housing 20 and the heat dissipation member 30 and supports the thermoelectric element 15, and the heat conduction member is made of the same metal as one of the housing 20 and the heat dissipation member 30 on which the heat conduction member is provided.

The thermoelectric power generation device 100 also includes a housing 20 and a heat dissipation member 30 made of different metals, a thermoelectric element 15 that is thermally connected to the housing 20 and the heat dissipation member 30 and generates an electromotive force in response to the temperature difference between the housing 20 and the heat dissipation member 30, a first heat conduction member 50 attached to the housing 20 and supporting the thermoelectric element 15, and a second heat conduction member 51 attached to the heat dissipation member 30 and supporting the thermoelectric element 15 together with the first heat conduction member 50, where the first heat conduction member 50 is made of the same metal as the housing 20, and the second heat conduction member 51 is made of the same metal as the heat dissipation member 30.

In these configurations, when the heat conducting member is attached to the housing 20, it is made of the same material as the housing 20, and when the heat conducting member is attached to the heat dissipation member 30, it is made of the same material as the heat dissipation member 30. This prevents electrolytic corrosion from occurring between the housing 20 or heat dissipation member 30 and the heat conducting member. This improves the durability of the thermoelectric generator 100.

In the thermal power generation device 100, the housing 20 and the first heat conducting member 50 are made of steel, the heat dissipation member 30 and the second heat conducting member 51 are made of aluminum or copper-based materials, the housing 20 is attached to the heat source (hydraulic cylinder 1), the heat dissipation member 30 is configured as a heat sink for dissipating heat from the heat dissipation member 30 to the atmosphere, the first heat conducting member 50 and the second heat conducting member 51 are formed in a rod shape, and the length L2 of the second heat conducting member 51 is longer than the length L1 of the first heat conducting member 50.

In this configuration, the second heat conducting member 51, which has a relatively high thermal conductivity, is configured to be longer than the first heat conducting member 50, thereby improving the power generation efficiency of the thermoelectric power generating device 100.

The thermoelectric generator 100 further includes a resin spacer 40 that is formed into a cylindrical shape and sandwiched between the housing 20 and the heat dissipation member 30, and the housing 20 and the heat dissipation member 30 are connected to each other via the resin spacer 40 that insulates the housing 20 and the heat dissipation member 30.

In this configuration, the spacer 40 insulates the housing 20 from the heat dissipation member 30, and prevents direct contact between the two, preventing the occurrence of electrolytic corrosion.

The thermoelectric generator 100 further includes a connecting member 52 that is provided on one of the housing 20 and the heat dissipation member 30 and has a female thread, and a resin screw 72 that is formed with a male thread that screws into the connecting member 52 and passes through the other of the housing 20 and the heat dissipation member 30 to connect the housing 20 and the heat dissipation member 30. A gap is formed between the connecting member 52 and the heat dissipation member 30, and they are separated from each other without touching each other.

In this configuration, the housing 20 and the heat dissipation member 30 are connected by resin screws 72, which prevents the occurrence of electrolytic corrosion caused by the use of metal screw members. In addition, the occurrence of electrolytic corrosion caused by contact between the connecting member 52 and the heat dissipation member 30 is prevented.

Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

1...hydraulic cylinder (heat source), 15...thermoelectric conversion element, 20...housing (first member), 30...heat dissipation member (second member), 40...spacer (insulating member), 50...first heat conductive member (heat conductive member), 51...second heat conductive member (heat conductive member), 52...connecting member (first screw member), 72...plastic screw (second screw member), 100...thermoelectric power generation device

Claims (5)

A first member and a second member made of different metals;
a thermoelectric conversion element thermally connected to each of the first member and the second member, the thermoelectric conversion element converting a temperature difference between the first member and the second member into electric power;
a first thermal conductive member provided on the first member and supporting the thermoelectric conversion element;
a second heat conducting member provided on the second member and supporting the thermoelectric conversion element together with the first heat conducting member,
the first thermally conductive member is made of the same metal as the first member;
the second thermally conductive member is made of the same metal as the second member;
A thermoelectric power generating device, characterized in that the first heat conducting member and the second heat conducting member are formed in a rod shape and support the thermoelectric conversion element at their respective ends . The first member is attached to a heat source,
The second member is configured as a heat sink for dissipating heat of the second member to the atmosphere,
the second member and the second thermal conductive member are formed of a material having a higher thermal conductivity than the first thermal conductive member,
The thermoelectric power generating device according to claim 1 , wherein the second heat conducting member is longer in length than the first heat conducting member. the first member and the first thermal conductive member are formed of a steel material,
the second member and the second thermal conductive member are formed of an aluminum-based or copper-based material,
The first member is attached to a heat source,
The second member is configured as a heat sink for dissipating heat of the second member to the atmosphere,
The thermoelectric power generating device according to claim 1 , wherein the second heat conducting member is longer in length than the first heat conducting member. a resin heat insulating member formed in a cylindrical shape and sandwiched between the first member and the second member;
4. The thermoelectric generator according to claim 1, wherein the first member and the second member are connected to each other via the heat insulating member. a first threaded member provided on one of the first member and the second member and having a female thread;
a second screw member made of resin, the second screw member having a male thread that screws into the female thread of the first screw member, and the second screw member being inserted through the other of the first member and the second member and screwed into the first screw member to connect the first member and the second member;
A thermoelectric generator according to any one of claims 1 to 4, characterized in that a gap is formed between the first screw member and the other of the first member and the second member, and the first screw member and the second member are spaced apart without contacting each other.

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