Heating apparatus

Abstract

To suppress an occurrence of an ion migration during an operation of a heating apparatus including a ceramic heater.SOLUTION: A heating apparatus 1 includes: a ceramic heater 10 having a cylindrical ceramic base and a linear resistance heating element embedded in the ceramic base, in which a base part 111 on which a first electrode pad 13 connected to one end of the resistance heating element and a second electrode pad 14 connected to the other end of the resistance heating element are formed, and a heating part 112 heated by the resistance heating element are formed; a first conductive member 61 connected to the first electrode pad 13; a second conductive member 62 connected to the second electrode pad 14; and a housing 20 that houses the ceramic heater 10. The housing 20 includes a first space S1 that accommodates the heating part 112 and a second space S2 that accommodates the base part 111. Then, the second space S2 is filled with a sealing member.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a heating device. [Background technology]

[0002] Ceramic heaters, which have a ceramic base with a resistance heating element embedded therein, are small and lightweight and have excellent insulation and temperature rise properties, and are therefore used for a variety of purposes. Patent Document 1 discloses a heating device that heats a medium such as a liquid using a ceramic heater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-160310 Summary of the Invention

[0004] When a medium is heated using a heating device equipped with a ceramic heater, the inside of the heating device becomes hot due to the heating of the medium. Furthermore, for example, when the heating device is installed in a vehicle, the external environment may be highly humid. In such a case, external humidity may enter the heating device, causing the inside of the heating device to become highly humid. When electricity is applied to the ceramic heater under such high-temperature, high-humidity conditions, ion migration may occur between a pair of conductive members that supply power to the ceramic heater. If ion migration occurs, the pair of conductive members may short-circuit, potentially damaging a control board or the like that controls the power supplied to the ceramic heater.

[0005] The present disclosure has an object to solve the above-mentioned problems. That is, one object of the present disclosure is to suppress the occurrence of ion migration during operation of a heating device equipped with a ceramic heater.

[0006] The heating device (1) according to the present disclosure includes a ceramic heater (10) having a cylindrical ceramic substrate and a resistance heating element embedded in the ceramic substrate, the ceramic heater (10) including a base (111) on the surface of which is formed a first electrode (13) connected to one end of the resistance heating element and a second electrode (14) connected to the other end of the resistance heating element, a heating element (112) heated by the resistance heating element, a first conductive member (61) connected to the first electrode (13), a second conductive member (62) connected to the second electrode (14), and a housing (20) that accommodates the ceramic heater (10). The housing (20) is formed with a first space (S1) that accommodates the heating element (112) and a second space (S2) that accommodates the base (111). A sealing member is filled in the second space (S2).

[0007] According to the heating device of the present disclosure, a sealing member is filled into the second space of the housing. A base of a ceramic heater is disposed in the second space, and a pair of electrodes (first and second electrodes) is formed on the surface of the base. A pair of conductive members (first and second conductive members) is connected to each of the pair of electrodes. Therefore, the base of the ceramic heater, the pair of electrodes (first and second electrodes), and the pair of conductive members (first and second conductive members) disposed in the second space are sealed by the sealing member filled into the second space. This ensures insulation between the pair of conductive members and removes moisture from the surrounding area. This prevents the second space from becoming highly humid, thereby suppressing ion migration between the pair of conductive members.

[0008] The pair of conductive members (first conductive member and second conductive member) are connected to a power supply source such as a control board to apply a predetermined voltage between the pair of electrodes. Because the power supply source is not disposed in the second space, the pair of conductive members have portions that are disposed in the second space and portions that are not disposed therein. Therefore, the portions of the pair of conductive members that are not disposed in the second space are not filled with sealing material. However, the portion of the conductive members that occurs in the vicinity of the electrode is the portion of the conductive members that is located in the vicinity of the electrode. Because the portion that is located in the vicinity of the electrode is disposed in the second space, filling this portion with sealing material can sufficiently suppress the occurrence of ion migration, even if the other portions are not filled with sealing material.

[0009] In this specification, the sealing member is a solid member that can insulate a component placed in a space by embedding the component and remove air from around the component. The sealing member preferably has low hygroscopicity and insulating properties. A potting agent is typically used as the sealing member. By using a potting agent as the sealing member, the second space can be easily filled with the sealing member. However, a potting agent with high hygroscopicity should not be used because ion migration may occur through the interior of the potting agent.

[0010] In one aspect of the heating device according to the present disclosure, the heating device (1) includes a fixing member (40) for fixing the ceramic heater (10) to the housing (20). The fixing member (40) is disposed in the second space (S2) and includes an enclosing portion (42) configured to surround the base (111), the first conductive member (61), and the second conductive member (62). A sealing member is filled in the enclosing space (S21), which is the internal space of the enclosing portion (42).

[0011] According to the above configuration, by filling the internal space (enclosed space) of the enclosed portion with a sealing material, it is possible to suppress the occurrence of ion migration between the first conductive member and the second conductive member arranged in the enclosed space.

[0012] In another aspect of the heating device according to the present disclosure, a ceramic heater (10) includes a cylindrical portion (11) having a base portion (111) and a heating portion (112) formed continuously in the axial direction, and a flange portion (12) extending radially outward from the cylindrical portion (11) from a boundary between the base portion (111) and the heating portion (112). A stepped wall portion (24) is formed between the first space (S1) and the second space (S2) of the housing (20), the stepped wall portion (24) communicating the first space (S1) and the second space (S2) and having a circular hole (244) with a diameter smaller than the outer diameter of the flange portion (12). The flange portion (12) abuts against the stepped wall portion (24), thereby separating the first space (S1) and the second space (S2).

[0013] According to the above configuration, the flange portion of the ceramic heater can separate the first space and the second space within the housing.

[0014] In yet another aspect of the heating device according to the present disclosure, the ceramic heater (10) is disposed in the housing (20) such that the axial direction of the cylindrical portion (11) is along a first direction (front-rear direction). The surrounding portion (42) includes a pair of opposing pieces (421, 421) spaced apart from each other in a second direction (left-right direction) perpendicular to the first direction (front-rear direction) and arranged opposite to each other so as to cover both sides of the base portion (111), a connecting piece (422) connecting one end (front end) of the pair of opposing pieces (421, 421) in the first direction (front-rear direction), and a bottom piece (423) closing an opening surrounded by one end (lower end) of the pair of opposing pieces (421, 421) and one end (lower end) of the connecting piece (422) in a third direction (up-down direction) perpendicular to the first direction (front-rear direction) and the second direction (left-right direction). The enclosed space (S21) is formed by a space surrounded by the pair of opposing pieces (421, 421), the connecting piece (422), and the bottom piece (423).

[0015] According to the above configuration, the sealing member can be filled into the enclosed space surrounded by the pair of opposing pieces, the connecting piece, and the bottom piece of the surrounding portion.

[0016] In yet another aspect of the heating device according to the present disclosure, the fixing member (40) has a pressing portion (43) formed to extend in directions (left-right and up-down directions) perpendicular to the first direction (front-rear direction) from the other end (rear end) of the pair of opposing pieces (421, 421) in the first direction (front-rear direction) and the other end (rear end) of the bottom piece (423) in the first direction (front-rear direction). The pressing portion (43) abuts against the flange portion (12), thereby fixing the ceramic heater (10) by the fixing member (40).

[0017] According to the above configuration, the ceramic heater can be fixed in the housing by the fixing member. Furthermore, when the retaining portion abuts against the flange portion, the enclosed space is surrounded by the pair of opposing pieces, the connecting piece, the bottom piece, and the flange portion. Therefore, if the enclosed space is a substantially rectangular parallelepiped space, five sides of the enclosed space are surrounded by the above-mentioned surfaces, and only one side of the enclosed space is open. Therefore, by filling the sealing member through the open surface, the sealing member can be retained within the enclosed space.

[0018] In yet another aspect of the heating device according to the present disclosure, the fixing member (40) has a cylindrical inlet passage portion (41) that has one end that opens to the connecting piece (422) and extends in a direction opposite to the enclosed space (S21). A base portion (111) disposed in the enclosed space (S21) is connected to one end of the inlet passage portion (41), thereby communicating the internal space of the inlet passage portion (41) with the internal space of the base portion (111).

[0019] According to the above configuration, the medium can be caused to flow from the inlet passage of the fixing member into the base of the ceramic heater and the internal space of the heating portion, and further the medium can be introduced from the heating portion into the first space of the housing.

[0020] In yet another aspect of the heating device according to the present disclosure, the housing (20) has a third space (S3) separated from the first space (S1), and a control board (30) for controlling the supply of electricity to the resistance heating element is disposed in the third space (S3). The first conductive member (61) and the second conductive member (62) extend from the first electrode (13) and the second electrode (14), respectively, toward the control board (30), and their respective tips are connected to the control board (30).

[0021] According to the above configuration, the control board can be housed in the heating device, and the pair of conductive members (first conductive member, second conductive member) can be connected to the control board.

[0022] In yet another aspect of the heating device according to the present disclosure, the housing (20) is formed with an outlet passage (27) for allowing the medium to flow out of the first space (S1). The heating device (1) also includes a first temperature sensor (71) for detecting the temperature of the medium flowing through the inlet passage (41) and a second temperature sensor (72) for detecting the temperature of the medium flowing through the outlet passage (27). A signal representing the temperature detected by the first temperature sensor (71) and a signal representing the temperature detected by the second temperature sensor (72) are transmitted to the control board (30).

[0023] According to the above configuration, the control board can control the power supply to the resistance heating element based on the temperature detected by the first temperature sensor or the temperature detected by the second temperature sensor.

[0024] In yet another aspect of the heating device according to the present disclosure, the sealing member is a potting agent whose main component is any of an olefin-based resin, an epoxy-based resin, and a silyl group-containing special polymer.

[0025] The potting material described above has low moisture absorption and high insulating properties, and therefore, by using the potting material described above as a sealing member, it is possible to sufficiently suppress the occurrence of ion migration.

[0026] In yet another aspect of the present disclosure, a heating device (1) is used to heat a medium flowing through a flow path formed in a device mounted on a vehicle.

[0027] According to the above configuration, it is possible to heat a medium flowing through a flow path formed in a device installed in a vehicle, such as a refrigerant flowing through a refrigerant circuit of a vehicle air conditioner or a temperature-control fluid flowing through a flow path formed in a temperature control device of an on-board battery. [Brief explanation of the drawings]

[0028] [Figure 1A] 1 is a perspective view of a heating device according to an embodiment; [Figure 1B] FIG. [Figure 2] FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1A. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. [Figure 6] FIG. 10 is a view of the cylindrical portion as seen from the right. [Figure 7] FIG. 4 is a cross-sectional view of the housing shown in FIG. 3. [Figure 8] FIG. 5 is a cross-sectional view of the housing shown in FIG. [Figure 9] 9 is a schematic view of the housing of FIG. 8 as viewed from the direction A. FIG. [Figure 10] FIG. 4 is an enlarged view of part B in FIG. 3. [Figure 11] FIG. 5 is an enlarged view of part C in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1A is a perspective view of a heating device 1 according to this embodiment, and FIG. 1B is a plan view of the heating device 1. FIG. 2 is an exploded perspective view of the heating device 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. In these and other drawings, when describing the heating device 1 and its components using directions, the front-to-back direction (first direction), left-to-right direction (second direction), and up-to-down direction (third direction) shown in FIG. 1A are used. These directions are mutually orthogonal. Furthermore, one of the front-to-back directions is referred to as the front, and the other as the rear; one of the left-to-right directions is referred to as the right, and the other as the left; and one of the up-to-down directions is referred to as the top, and the other as the bottom. Even when describing components of the heating device 1 individually, the directions shown in FIG. 1 when the components are assembled to the heating device 1 will be used. Note that the upper plate 70 shown in FIG. 1A is only shown in FIG. 1A and is not shown in other drawings.

[0030] The heating device 1 according to this embodiment can be mounted on a vehicle. The heating device 1 can be used to heat a medium flowing through a flow path formed in a device mounted on the vehicle. Examples of devices mounted on a vehicle include a vehicle air conditioning device and an on-board battery. Examples of flow paths formed in a device mounted on a vehicle include a refrigerant circuit of a vehicle air conditioning device and a flow path formed in a temperature control device for controlling the temperature of an on-board battery. Examples of a medium flowing through a flow path formed in a device mounted on a vehicle include a refrigerant flowing through a refrigerant circuit of a vehicle air conditioning device and a temperature control fluid flowing through a flow path formed in a temperature control device for an on-board battery. In this specification, the term "medium" is a general term for a fluid used to transfer heat. In the following, an example will be described in which a liquid such as a liquid refrigerant or coolant is used as the medium.

[0031] As shown in FIG. 2, the heating device 1 includes a ceramic heater 10, a housing 20, a control board 30, a fixing bracket 40, and an inlet plate 50.

[0032] The ceramic heater 10 has a cylindrical portion 11 and a flange portion 12. The cylindrical portion 11 is a portion formed in a cylindrical shape with both ends open. The flange portion 12 is formed in a ring shape and is fixed coaxially to the outer peripheral wall surface of the cylindrical portion 11.

[0033] FIG. 5 is a view of the cylindrical portion 11 as seen from above, and FIG. 6 is a view of the cylindrical portion 11 as seen from the right. In FIG. 6, a portion of the cylindrical portion 11 is shown in cross section. The cylindrical portion 11 has a resistance heating element and a ceramic base. The resistance heating element is a linear member that generates heat when electricity is passed through it, and is composed of a long conductor that forms a predetermined pattern. An example of the resistance heating element is tungsten. The resistance heating element is embedded in a cylindrical ceramic base. The ceramic base is a member for heating an object to be heated, and is heated by the resistance heating element embedded in it. The ceramic base is made of ceramic. The ceramic base is made of alumina, for example.

[0034] The cylindrical portion 11 can be produced, for example, as follows: A resistance heating element formed in a predetermined pattern is sandwiched between two ceramic green sheets to produce a laminate, and the laminate is then wound around a cylindrical ceramic body. Thereafter, the ceramic body around which the laminate is wound is fired, thereby producing the cylindrical portion 11 having the resistance heating element and the ceramic base in which the resistance heating element is embedded.

[0035] As shown in Figures 5 and 6, the cylindrical portion 11 is formed with a base portion 111 and a heating portion 112. The base portion 111 is formed in a region including the front end portion of the cylindrical portion 11. The heating portion 112 is composed of the portion of the cylindrical portion 11 other than the base portion 111. The base portion 111 and the heating portion 112 are formed continuously in the axial direction. The axial length of the heating portion 112 is longer than the axial length of the base portion 111.

[0036] A first electrode pad 13 (first electrode) and a second electrode pad 14 (second electrode) are formed on the outer peripheral surface (surface) of the base 111. Both the first electrode pad 13 and the second electrode pad 14 are made of a conductive material such as metal. One end of a first conductive member 61 shown in FIG. 2 is connected to the first electrode pad 13. One end of a second conductive member 62 is connected to the second electrode pad 14. Lead terminals are exemplified as the first conductive member 61 and the second conductive member 62. The other ends of the first conductive member 61 and the second conductive member 62 are electrically connected to predetermined positions on the control board 30, respectively.

[0037] The resistance heating element of the cylindrical portion 11 is embedded in a cylindrical ceramic base so as to form a predetermined pattern mainly inside the heating portion 112. Therefore, the heating portion 112 is the portion that is heated by the resistance heating element. Both ends of the resistance heating element are extended to the base portion 111, and the respective ends of the resistance heating element are connected to a first electrode pad 13 and a second electrode pad 14 formed on the outer peripheral surface of the base portion 111. Therefore, when a predetermined voltage is applied between the first electrode pad 13 (first conductive member 61) and the second electrode pad 14 (second conductive member 62), electricity is passed through the resistance heating element (current flows).

[0038] The flange portion 12 is formed in a ring shape from ceramic. The flange portion 12 may be formed from the same material as the ceramic substrate that constitutes the cylindrical portion 11. For example, the flange portion 12 can be formed from alumina. The flange portion 12 is joined to the cylindrical portion 11 by, for example, brazing. The flange portion 12 extends radially outward from the boundary position between the base portion 111 and the heating portion 112 of the cylindrical portion 11. Therefore, the flange portion 12 divides the cylindrical portion 11 into the base portion 111 and the heating portion 112.

[0039] The housing 20 functions as a container for accommodating the ceramic heater 10 and the control board 30, and also forms a flow path for the liquid heated by the heating device 1. Fig. 7 shows a cross-sectional view of the housing 20 shown in Fig. 3, and Fig. 8 shows a cross-sectional view of the housing 20 shown in Fig. 4.

[0040] As shown in FIGS. 7 and 8, the housing 20 has a heating chamber 21 (first chamber), a power supply chamber 22 (second chamber), and a substrate accommodating chamber 23 (third chamber). A first space S1 is formed within the heating chamber 21, a second space S2 is formed within the power supply chamber 22, and a third space S3 is formed within the substrate accommodating chamber 23. That is, the housing 20 is formed with the first space S1, the second space S2, and the third space S3. The first space S1 accommodates the heating portion 112 of the ceramic heater 10 and is a space in which a flow path for a liquid serving as a heated object is formed. The second space S2 accommodates the base 111 and flange portion 12 of the ceramic heater 10. The third space S3 accommodates the control board 30.

[0041] As shown in FIG. 2, the second space S2 is formed in the front portion of the housing 20 and is a space with an open front end. The power supply chamber 22 that forms the second space S2 has a right front wall portion 221, a left front wall portion 222, a bottom wall portion 223, and an upper wall portion 224. The right front wall portion 221 and the left front wall portion 222 are arranged facing each other with a space between them in the left-right direction and are wall members having surfaces that are perpendicular to the left-right direction (surfaces that extend in the front-rear and up-down directions). The bottom wall portion 223 is formed in a flat plate shape so as to connect the lower end edge of the right front wall portion 221 to the lower end edge of the left front wall portion 222. The upper wall portion 224 is formed so as to connect the upper end edge of the right front wall portion 221 to the upper end edge of the left front wall portion 222. The second space S2 is formed by the space surrounded by these wall portions.

[0042] The third space S3 is formed in the upper portion of the housing 20 and is a space with an open upper end. The substrate accommodating chamber 23 that forms the third space S3 has a right rear wall portion 231, a left rear wall portion 232, a rear wall portion 233, and a partition wall portion 234. The right rear wall portion 231 and the left rear wall portion 232 are wall members that are arranged facing each other and spaced apart in the left-right direction, and have surfaces that are perpendicular to the left-right direction. The vertical length of the right rear wall portion 231 is shorter than the vertical length of the right front wall portion 221, and the vertical length of the left rear wall portion 232 is shorter than the vertical length of the left front wall portion 222. The right rear wall 231 is formed integrally with the upper half of the right front wall 221 so as to extend rearward from the rear end of the upper half of the right front wall 221, and the left rear wall 232 is formed integrally with the upper half of the left front wall 222 so as to extend rearward from the rear end of the upper half of the left front wall 222. The rear wall 233 is formed in a flat plate shape so as to connect the rear end edge of the right rear wall 231 and the rear end edge of the left rear wall 232, and is a wall member having a surface perpendicular to the front-rear direction (a surface extending in the left-right and up-down directions). The partition wall 234 is formed in a flat plate shape so as to close an opening formed by the lower end edge of the right rear wall 231, the lower end edge of the left rear wall 232, and the lower end edge of the rear wall 233. The space surrounded by these walls forms a third space S3.

[0043] The first space S1 is formed behind the second space S2 and below the third space S3. As shown in FIGS. 7 and 8, the first space S1 has a truncated cone shape with an axis parallel to the front-rear direction and tapering toward the rear. The heating chamber 21 forming the first space S1 has a peripheral wall 211 and a leading wall 212. The peripheral wall 211 is a wall member whose inner peripheral surface forms the side periphery of the truncated cone-shaped first space S1. The upper portion of the peripheral wall 211 is connected to the lower end of the partition wall 234 of the substrate accommodating chamber 23. The leading wall 212 is a wall member whose surface is perpendicular to the front-rear direction and whose front surface forms the ceiling of the truncated cone-shaped first space S1. FIG. 9 is a schematic diagram of the housing 20 in FIG. 8 as viewed from direction A. As shown in FIG. 9, the leading wall 212 has a generally semicircular shape that is convex downward when viewed from the rear. The upper portion of the tip wall portion 212 is integrally connected to the lower end portion of the rear wall portion 233 of the substrate accommodating chamber 23 .

[0044] As shown in FIGS. 3 and 7, an outlet passage 27 is formed in the peripheral wall 211 of the heating chamber 21 of the housing 20. The outlet passage 27 is formed in a cylindrical shape so as to protrude leftward from a predetermined position in front of and on the left side of the peripheral wall 211. The outlet passage 27 is a piping member for causing the liquid in the first space S1 to flow out. Also, as shown in FIG. 3, an outlet temperature sensor 72 is attached to the outlet passage 27. The outlet temperature sensor 72 detects the temperature of the liquid flowing in the outlet passage 27 and transmits a signal indicating the detected temperature to the control board 30.

[0045] As shown in FIGS. 7 and 8 , a stepped wall portion 24 is formed at the rear end of each of the right front wall portion 221, the left front wall portion 222, and the bottom wall portion 223 that constitute the power supply chamber 22. The stepped wall portion 24 is formed between the first space S1 and the second space S2. The stepped wall portion 24 has an inner circumferential wall surface 241 and a seating surface 242. The inner circumferential wall surface 241 is a cylindrical inner wall surface with an axis in the front-rear direction, and its diameter is approximately equal to the outer diameter of the flange portion 12. The seating surface 242 is formed radially inward from the rear end of the inner circumferential wall surface 241. The seating surface 242 is formed in a ring shape and faces forward. An O-ring groove 243 is formed in this seating surface 242. An O-ring 81 (see FIG. 2) is fitted into the O-ring groove 243. A circular hole 244 is formed on the inner periphery of the ring-shaped seating surface 242. The diameter of the circular hole 244 is smaller than the outer diameter of the flange portion 12. The opening surface of this circular hole 244 forms the bottom surface (front surface) of the first space S1 having a truncated cone shape. Therefore, the first space S1 and the second space S2 communicate with each other via the circular hole 244.

[0046] 8, a gap is formed between the upper portion of the stepped wall portion 24 and the upper wall portion 224, and the second space S2 and the third space S3 communicate with each other through this gap. On the other hand, the third space S3 is liquid-tightly partitioned from the first space S1 by the partition wall portion 234.

[0047] 4, the control board 30 is accommodated in the third space S3 of the housing 20. The control board 30 is placed horizontally on the partition wall portion 234 of the board accommodating chamber 23 within the third space S3 via a spacer SP. The control board 30 is a control device for controlling the supply of electricity to the resistance heating element.

[0048] The ceramic heater 10 is accommodated in the first space S1 and the second space S2 of the housing 20. When accommodating the ceramic heater 10 in the housing 20, the ceramic heater 10 is inserted from the front-end opening of the second space S2 of the housing 20. At this time, the ceramic heater 10 is inserted into the second space S2 from the rear end side of the heating portion 112. The heating portion 112 of the ceramic heater 10 is further inserted into the first space S1 through the circular hole 244 of the stepped wall portion 24. Then, with the rear portion of the flange portion 12 of the ceramic heater 10 fitted into the inner circumferential wall surface 241 of the stepped wall portion 24 of the housing 20, the outer circumferential portion of the rear end surface of the flange portion 12 abuts against the seat surface 242 of the stepped wall portion 24, thereby locking the flange portion 12 to the stepped wall portion 24. As a result, the ceramic heater 10 is disposed in the housing 20 so that the axial direction of the cylindrical portion 11 of the ceramic heater 10 is aligned with the front-rear direction. 3 and 4, the heating portion 112 of the ceramic heater 10 is accommodated in the first space S1, and the base 111 and flange 12 of the ceramic heater 10 are accommodated in the second space S2. The ceramic heater 10 is inserted into the housing 20 so that the first electrode pad 13 and the second electrode pad 14 provided on the base 111 of the ceramic heater 10 are spaced apart in the left-right direction. At this time, a first conductive member 61, one end of which is connected to the first electrode pad 13, and a second conductive member 62, one end of which is connected to the second electrode pad 14, extend upward and rearward from the respective electrode pads 13, 14 toward the control board 30 in the third space S3. The other ends (tips) of these conductive members 61, 62 enter the third space S3 through the gap between the stepped wall portion 24 and the upper wall portion 224 and are electrically connected to predetermined positions on the control board 30 in the third space S3. In this case, the first conductive member 61 and the second conductive member 62 may be connected directly to a predetermined position on the control board 30, or may be connected to a predetermined position on the control board 30 via another conductive member.

[0049] The fixing bracket 40 is provided to fix the ceramic heater 10 to the housing 20. As shown in FIG.

[0050] The inlet passage 41 is formed in a cylindrical shape with a front end opening and a rear end opening. As shown in FIG. 2, the surrounding portion 42 includes a pair of opposing pieces 421 and a connecting piece 422. The pair of opposing pieces 421 are spaced apart from each other in the left-right direction and are plate-like portions having surfaces perpendicular to the left-right direction (surfaces extending in the up-down and front-rear directions). The connecting piece 422 is a plate-like portion connecting the front ends of the pair of opposing pieces 421 and 421. The surrounding portion 42 further includes a bottom piece 423 (see FIG. 4). The bottom piece 423 is a plate-like portion configured to close the opening surrounded by the lower ends of the pair of opposing pieces 421 and 421 and the lower end of the connecting piece 422. The bottom piece 423 is formed in a plate-like shape with surfaces perpendicular to the up-down direction so as to extend rearward from the lower end edge of the connecting piece 422, and its left and right sides are connected to the lower ends of the pair of opposing pieces 421 and 421, respectively. The pair of opposing pieces 421, 421, the connecting piece 422, and the bottom piece 423 form within the surrounding portion 42 a substantially rectangular parallelepiped space (surrounding space) that is open at the top and rear.

[0051] The rear end of the inlet passage portion 41 opens to the connecting piece 422. The inlet passage portion 41 is formed to extend from the opening to the connecting piece 422 in the direction opposite (forward) to the internal space of the surrounding portion 42 (surrounding space).

[0052] The retaining portion 43 is formed in a flat plate shape so as to extend in directions perpendicular to the front-rear direction (left-right and up-down directions) from the rear ends of the pair of opposing pieces 421, 421 of the surrounding portion 42 and the rear end of the bottom piece 423. The retaining portion 43 is formed so as to extend outward from the enclosed space without entering the rear opening of the enclosed space.

[0053] The fixing bracket 40 is disposed in front of the ceramic heater 10 disposed in the housing 20. Specifically, as shown in Figures 3 and 4, it is disposed relative to the ceramic heater 10 so that the pressing portion 43 abuts against the flange portion 12 of the ceramic heater 10 disposed in the housing 20 from the front. At this time, the pressing portion 43 and the surrounding portion 42 of the fixing bracket 40 are disposed in the second space S2 of the housing 20. The base portion 111 of the cylindrical portion 11 of the ceramic heater 10 is disposed in the surrounding space surrounded by the surrounding portion 42 disposed in the second space S2. Meanwhile, the inlet passage portion 41 of the fixing bracket 40 is disposed in a state where it protrudes forward from the second space S2 of the housing 20. The inlet passage 41 and the cylindrical portion 11 of the ceramic heater 10 are arranged coaxially, and the rear end opening edge of the inlet passage 41 and the front end opening edge of the base 111 of the ceramic heater 10 are abutted together, with the gap between them being sealed by an O-ring 82 (see FIG. 2). This allows communication between the space inside the inlet passage 41 and the space inside the base 111. An inlet temperature sensor 71 is attached to the inlet passage 41. The inlet temperature sensor 71 detects the temperature of the liquid flowing inside the inlet passage 41 and sends a signal indicating the detected temperature to the control board 30.

[0054] FIG. 10 is an enlarged view of portion B in FIG. 3, and FIG. 11 is an enlarged view of portion C in FIG. 4. As described above, the surrounding portion 42 of the fixing bracket 40 is disposed in the second space S2 of the housing 20. Therefore, as shown in FIGS. 10 and 11, a surrounding space S21, which is a space surrounded by the surrounding portion 42, is formed in the second space S2. The surrounding portion 42 is configured to surround the base 111, the first electrode pad 13 and the second electrode pad 14 formed on the outer peripheral surface of the base 111, the first conductive member 61 having one end connected to the first electrode pad 13, and the second conductive member 62 having one end connected to the second electrode pad 14. In other words, the base 111 of the ceramic heater 10, the first electrode pad 13, the second electrode pad 14, the first conductive member 61, and the second conductive member 62 are disposed in the surrounding space S21 surrounded by the surrounding portion 42. At this time, the pair of opposing pieces 421, 421 of the surrounding portion 42 are arranged opposite to each other and spaced apart in the left-right direction so as to cover both sides (right and left) of the base portion 111 of the cylindrical portion 11.

[0055] Additionally, the retaining portion 43 of the fixing bracket 40 abuts against the flange portion 12 of the ceramic heater 10. As a result, the rear opening of the enclosed space S21 is blocked by the flange portion 12. Furthermore, the rear end of the inlet passage portion 41, which opens to the connecting piece 422 of the enclosed portion 42, is blocked by the front end of the base portion 111 of the ceramic heater 10 and the O-ring 82. Therefore, the front surface of the substantially rectangular parallelepiped enclosed space S21 faces the connecting piece 422, the rear surface faces the flange portion 12, the left and right surfaces face the pair of opposing pieces 421, 421, and the bottom surface faces the bottom piece 423. In other words, five sides of the substantially rectangular parallelepiped enclosed space S21 are surrounded by wall members. Therefore, only the top end of the enclosed space S21 is open.

[0056] The enclosed space S21 is filled with a potting agent as a sealing material. As described above, since the enclosed space S21 is open only at its upper end, by filling the enclosed space S21 with the potting agent from the open upper end, the potting agent is contained within the enclosed space S21 and does not leak out to the outside. When the potting agent filled in the enclosed space S21 solidifies, the components disposed in the enclosed space S21, specifically, the base 111 of the ceramic heater 10, the first electrode pad 13, the second electrode pad 14, the first conductive member 61, and the second conductive member 62, are embedded and sealed in the potting agent. Note that portions of the first conductive member 61 and the second conductive member 62 are embedded in the potting agent. Specifically, the portion of the first conductive member 61 connected to the first electrode pad 13 and its adjacent portion, and the portion of the second conductive member 62 connected to the second electrode pad 14 and its adjacent portion are embedded (sealed) in the potting agent.

[0057] In this embodiment, a potting agent whose main component is an olefin-based resin is used as the potting agent. However, potting agents with other components can also be used. For example, potting agents whose main component is an epoxy resin (epoxy-based resin) or a silyl group-containing special polymer can be used. However, potting agents whose main component is a silicone resin are not used.

[0058] As shown in Figures 1A, 1B, and 2, the inlet plate 50 has a water inlet 51, a bracket accommodating section 52, and a lid section 53. The water inlet 51 is cylindrical with an axis along the front-to-rear direction. Liquid to be heated by the heating device 1 is supplied from the front end of the water inlet 51. The rear end of the water inlet 51 opens into the bracket accommodating section 52. The bracket accommodating section 52 is formed in a bag shape so that the inlet passage section 41 of the fixed bracket 40 can be accommodated therein. The lid section 53 is formed from the rear end of the bracket accommodating section 52. The lid section 53 is formed in a flat plate shape with a surface perpendicular to the front-to-rear direction so that its outer shape matches the outer shape of the front-end opening of the second space S2 (power supply chamber 22) of the housing.

[0059] 3 and 4, the outer periphery of the cover 53 of the inlet plate 50 abuts against the front end surfaces of the right front wall 221, left front wall 222, bottom wall 223, and top wall 224 that constitute the power supply chamber 22 of the housing 20. At this time, the inlet passage 41 of the fixed bracket 40 is housed in the bracket housing 52 of the inlet plate 50. The inlet passage 41 housed in the bracket housing 52 is arranged coaxially with the water inlet 51 of the inlet plate 50, and its front opening edge abuts against the rear opening edge of the water inlet 51, with the gap between them being sealed by an O-ring 83 (see FIG. 2). This connects the internal spaces of the water inlet 51 and the inlet passage 41.

[0060] As shown in FIG. 2 , protrusions 531 protruding outward are provided at multiple locations along the periphery of the lid portion 53, and circular holes are formed in these protrusions 531 that penetrate in the front-to-rear direction. Furthermore, protrusions 226 protruding outward are provided at multiple locations along the periphery of the front-end opening edge of the power supply chamber 22 of the housing 20, and screw holes are formed in these protrusions 226. These screw holes open to the front of the protrusions 226 and extend rearward from the opening. The positions of the multiple protrusions 531 and the positions of the multiple protrusions 226 coincide in the front-to-rear direction when the outer periphery of the lid portion 53 is butted against the front-end surfaces of the power supply chamber 22 (right front wall 221, left front wall 222, bottom wall 223, and top wall 224) of the housing 20. Therefore, the circular holes formed in the protrusions 531 and the screw holes formed in the protrusions 226 are coaxially arranged in the front-to-rear direction. Then, by inserting a screw into the circular hole formed in the protrusion 531 and threading this screw into the screw hole of the protrusion 226, the inlet plate 50 is attached to the housing 20 and the front end opening of the second space S2 of the housing 20 is closed by the lid portion 53.

[0061] Furthermore, the screw fastening force generated when fixing the inlet plate 50 to the housing 20 acts on the fixing bracket 40 arranged behind the inlet plate 50. As a result, the pressing portion 43 of the fixing bracket 40 is pressed strongly against the flange portion 12 of the ceramic heater 10, and the flange portion 12 of the ceramic heater 10 is further pressed strongly via the O-ring 81 against the seat surface 242 of the stepped wall portion 24 of the housing 20. In this way, the pressing portion 43 of the fixing bracket 40 comes into strong contact with the flange portion 12, thereby fixing the ceramic heater 10 to the housing 20, and the flange portion 12 and the O-ring 81 liquid-tightly partition the first space S1 and the second space S2 within the housing 20.

[0062] 2, a connector connection portion 28 is formed on the right rear side wall portion 231 of the housing 20. An electric wire for connecting the control board 30 arranged in the third space S3 of the housing 20 to an external electronic device is inserted into this connector connection portion 28. Also, as shown in FIG. 1A, an upper plate 70 for closing an upper opening of the third space S3 of the housing 20 is attached to the housing 20.

[0063] In the heating device 1 configured as described above, liquid as a heated object is introduced through the water inlet 51 of the inlet plate 50. As shown by the arrows in FIG. 3 , the liquid introduced into the water inlet 51 is supplied from the water inlet 51 to the inlet passage 41 of the fixing bracket 40 and then flows into the heating portion 112 via the base 111 of the cylindrical portion 11 of the ceramic heater 10. The liquid that flows into the heating portion 112 flows from front to rear inside the heating portion 112 and exits the heating portion 112 from its rear end. The liquid that exits the heating portion 112 flows into the first space S1, turns back at the rear end of the first space S1, and then flows from rear to front through the space between the outer peripheral surface of the heating portion 112 and the inner peripheral surface of the peripheral wall portion 211 of the housing 20. The liquid that flows from rear to front inside the first space S1 in this manner flows out into the outlet passage 27 and is discharged from the outlet passage 27 to the outside.

[0064] Furthermore, when liquid is flowing through the housing 20 of the heating device 1 as described above, a predetermined voltage is applied from the control board 30 between the first conductive member 61 (first electrode pad 13) and the second conductive member 62 (second electrode pad 14). This causes electricity to flow through the resistance heating element of the ceramic heater 10, causing the resistance heating element to generate heat, which in turn heats the heating portion 112 of the ceramic heater 10. Therefore, the liquid flowing inside the heating portion 112 and in the space between the outer peripheral surface of the heating portion 112 and the inner peripheral surface of the peripheral wall portion 211, i.e., the liquid flowing within the first space S1 of the housing 20, is heated by the heating portion 112. The liquid heated in this manner is discharged from the outlet passage 27.

[0065] Furthermore, the control board 30 acquires the temperature of the liquid introduced into the heating device 1 as the inlet temperature Tin based on a signal received from the inlet temperature sensor 71, and acquires the temperature of the liquid heated by the heating device 1 as the outlet temperature Tout based on a signal received from the outlet temperature sensor 72. The control board 30 then controls the amount of electricity (output) supplied to the resistance heating element so that the outlet temperature Tout coincides with a predetermined target temperature T*. In this case, for example, electricity supplied to the resistance heating element can be controlled by PI control based on the deviation between the outlet temperature Tout and the target temperature T* so that the outlet temperature Tout coincides with the target temperature T*.

[0066] While the heating device 1 heats the liquid, the second space S2 in the housing 20 becomes hot due to the influence of the ceramic heater 10 heating the liquid. Furthermore, water vapor in the air enters the second space S2, creating a high-humidity state in the second space S2. Therefore, while the heating device 1 is operating, the atmosphere in the second space S2 becomes hot and humid. When a predetermined voltage is applied to the first conductive member 61 and the second conductive member 62 disposed in the second space S2 in such a high-temperature, high-humidity state, causing a current to flow through the resistance heating element, ion migration is likely to occur. Ion migration is particularly likely to occur between the first conductive member 61 and the second conductive member 62, which supply power to the resistance heating element. Ion migration between the first conductive member 61 and the second conductive member 62 could cause a short circuit and damage the control board 30. Therefore, it is necessary to suppress ion migration between the first conductive member 61 and the second conductive member 62.

[0067] In the heating device 1 according to this embodiment, a potting agent is filled into the enclosed space S21, which is surrounded by the enclosed portion 42 of the fixing bracket 40 disposed in the second space S2. Therefore, the components disposed in the enclosed space S21, specifically, the base 111 of the ceramic heater 10, the first electrode pad 13, the second electrode pad 14, the first conductive member 61, and the second conductive member 62, are embedded and sealed in the potting agent. Therefore, the potting agent removes air from around these components, thereby removing moisture from around these components. Furthermore, because the potting agent is made of an insulating material with low hygroscopicity, ion migration does not occur within the potting agent. Therefore, ion migration between the first conductive member 61 and the second conductive member 62 embedded in the potting agent within the enclosed space S21 can be suppressed.

[0068] Furthermore, by filling the enclosed space S21 with a potting agent, it is possible to reliably insulate the first electrode pad 13 and the second electrode pad 14 in the enclosed space S21, and to insulate these electrode pads from the fixing bracket 40. Furthermore, the potting agent filled in the enclosed space S21 can fix the ceramic heater 10 to the fixing bracket 40.

[0069] Because the first conductive member 61 and the second conductive member 62 extend from the enclosed space S21 toward the control board 30, only the portions disposed in the enclosed space S21 are sealed with the potting material, and the portions protruding from the enclosed space S21 are not embedded in the potting material. However, ion migration is likely to occur in areas close to the electrode pads 13 and 14 to which one end of each conductive member 61 and 62 is connected. Furthermore, because the portion of the first conductive member 61 near the portion connected to the first electrode pad 13 and the portion of the second conductive member 62 near the portion connected to the second electrode pad 14 are disposed within the enclosed space S21, these portions are embedded and sealed in the potting material. Therefore, sealing these portions with the potting material sufficiently suppresses the occurrence of ion migration.

[0070] Although the embodiments of the present disclosure have been described above, the technology of the present disclosure is not limited to the above embodiments. For example, in the above embodiments, an example was shown in which a potting agent primarily composed of an olefin resin was used as the sealing material filled in the enclosed space S21. However, any sealing material other than a potting agent primarily composed of an olefin resin can be used as long as it is insulating, has low hygroscopicity, and can be filled into the enclosed space S21. Furthermore, in the above embodiments, the sealing material can suppress the occurrence of ion migration. However, the sealing material can also suppress the occurrence of electrolytic corrosion of the sealed components and the formation of whiskers in the sealed components. Furthermore, the enclosed space S21 does not need to be completely filled with the potting material; it is sufficient that the potting material is filled in the enclosed space S21 to the extent that it fills the areas where ion migration occurs. Furthermore, the control board 30 may use a signal received from the inlet temperature sensor 71 to control the power supply to the resistance heating element or for other control purposes. Furthermore, the directions defined in the above embodiment for explaining the configuration of the heating device 1 are merely examples, and in actual use, the heating device 1 can be operated in various directions. In this way, the technology according to the present disclosure can be modified without departing from the spirit thereof.

[0071] Furthermore, the present disclosure may include the following aspects. [1] a ceramic heater having a cylindrical ceramic base and a resistance heating element embedded in the ceramic base, the ceramic heater having a base portion on the surface of which a first electrode connected to one end of the resistance heating element and a second electrode connected to the other end of the resistance heating element are formed, and a heating portion heated by the resistance heating element; a first conductive member connected to the first electrode; a second conductive member connected to the second electrode; a housing that accommodates the ceramic heater; A heating device comprising: The housing is formed with a first space for accommodating the heating portion and a second space for accommodating the base portion, A sealing member is filled in the second space. heating device. [2] [1] The heating device according to a fixing member for fixing the ceramic heater to the housing; the fixing member includes a surrounding portion disposed in the second space and configured to surround the base portion, the first conductive member, and the second conductive member; The sealing member is filled in an enclosed space, which is an internal space of the enclosed portion. heating device. [3] [1] or [2], the heating device according to the ceramic heater comprises a cylindrical portion in which the base portion and the heating portion are formed continuously in the axial direction, and a flange portion extending radially outward from a boundary position between the base portion and the heating portion of the cylindrical portion, a stepped wall portion is formed between the first space and the second space of the housing, the stepped wall portion communicating with the first space and the second space and including a circular hole having a diameter smaller than an outer diameter of the flange portion; The flange portion abuts against the stepped wall portion, thereby dividing the first space and the second space. heating device. [4] [3] The heating device according to [3], the ceramic heater is disposed in the housing such that the axial direction of the cylindrical portion is along a first direction, the surrounding portion has a pair of opposing pieces spaced apart from each other in a second direction perpendicular to the first direction and arranged opposite to each other so as to cover both sides of the base portion, a connecting piece connecting one ends of the pair of opposing pieces in the first direction, and a bottom piece closing an opening surrounded by one ends of the pair of opposing pieces and one end of the connecting piece in a third direction perpendicular to the first direction and the second direction, The enclosed space is formed by a space surrounded by the pair of opposing pieces, the connecting piece, and the bottom piece. heating device. [5] [4] The heating device according to [4], the fixing member has a pressing portion formed so as to extend in a direction perpendicular to the first direction from the other end portions of the pair of opposing pieces in the first direction and the other end portion of the bottom piece in the first direction, The ceramic heater is fixed by the fixing member when the pressing portion abuts against the flange portion. heating device. [6] [4] or [5], the heating device according to the fixing member has one end that opens to the connecting piece and a cylindrical inlet passage portion that extends in a direction opposite to the enclosed space, The base portion disposed in the enclosed space is connected to one end of the inlet passage portion, thereby communicating an internal space of the inlet passage portion with an internal space of the base. heating device. [7] [1] to [6], the heating device according to any one of [1] to [6], The housing has a third space partitioned from the second space, a control board for controlling the supply of electricity to the resistance heating element is disposed in the third space; the first conductive member and the second conductive member extend from the first electrode and the second electrode toward the control board, respectively, and have their respective tip ends connected to the control board; heating device. [8] [1] to [7], the heating device according to any one of the above items, The housing has an outlet passage formed therein for allowing the medium to flow out of the first space, a first temperature sensor that detects the temperature of a medium flowing through the inlet passage portion, and a second temperature sensor that detects the temperature of a medium flowing through the outlet passage portion, a signal representing the temperature detected by the first temperature sensor and a signal representing the temperature detected by the second temperature sensor are transmitted to the control board; heating device. [9] [1] to [8], wherein the heating device is The sealing member is a potting agent containing, as a main component, any one of an olefin-based resin, an epoxy-based resin, and a silyl group-containing special polymer. heating device.

[10] [1] to [9], the heating device according to any one of the above, A heating device used to heat a medium flowing through a flow path formed in a device mounted on a vehicle. [Explanation of symbols]

[0072] 1...heating device, 10...ceramic heater, 11...cylindrical portion, 111...base portion, 112...heating portion, 12...flange portion, 13...first electrode pad (first electrode), 14...second electrode pad (second electrode), 20...housing, 21...heating chamber, 211...circumferential wall portion, 212...tip wall portion, 22...power supply chamber, 221...right front wall portion, 222...left front wall portion, 223...bottom wall portion, 224...upper wall portion, 23...substrate accommodating chamber, 231...right rear wall portion, 232...left rear wall portion, 233...rear wall portion, 234...partition wall portion, 24...step wall portion, 241...inner peripheral wall surface, 242...seat surface, 243...ring groove, 244...circular hole, 27...outlet passage portion, 30...control board, 40...fixing bracket (fixing member), 41...inlet passage portion, 42...surrounding portion, 421...facing piece, 422...connecting piece, 423...bottom piece, 43...holding portion, 50...inlet plate, 51...water inlet, 52...bracket accommodating portion, 53...lid portion, 61...first conductive member, 62...second conductive member, 70...upper plate, 71...inlet temperature sensor, 72...outlet temperature sensor, S1...first space, S2...second space, S21...surrounding space, S3...third space

Claims

1. a ceramic heater having a cylindrical ceramic base and a resistance heating element embedded in the ceramic base, the ceramic heater having a base portion on the surface of which a first electrode connected to one end of the resistance heating element and a second electrode connected to the other end of the resistance heating element are formed, and a heating portion heated by the resistance heating element; a first conductive member connected to the first electrode; a second conductive member connected to the second electrode; a housing that accommodates the ceramic heater; A heating device comprising: The housing is formed with a first space for accommodating the heating portion and a second space for accommodating the base portion, A sealing member is filled in the second space. heating device.

2. The heating device according to claim 1, a fixing member for fixing the ceramic heater to the housing; the fixing member includes a surrounding portion disposed in the second space and configured to surround the base portion, the first conductive member, and the second conductive member; The sealing member is filled in an enclosed space, which is an internal space of the enclosed portion. heating device.

3. The heating device according to claim 2, the ceramic heater comprises a cylindrical portion in which the base portion and the heating portion are formed continuously in the axial direction, and a flange portion extending radially outward from a boundary position between the base portion and the heating portion of the cylindrical portion, a stepped wall portion is formed between the first space and the second space of the housing, the stepped wall portion communicating with the first space and the second space and including a circular hole having a diameter smaller than an outer diameter of the flange portion; The flange portion abuts against the stepped wall portion, thereby dividing the first space and the second space. heating device.

4. The heating device according to claim 3, the ceramic heater is disposed in the housing such that the axial direction of the cylindrical portion is along a first direction, the surrounding portion has a pair of opposing pieces spaced apart from each other in a second direction perpendicular to the first direction and arranged opposite to each other so as to cover both sides of the base portion, a connecting piece connecting one end of the pair of opposing pieces in the first direction, and a bottom piece closing an opening surrounded by one end of the pair of opposing pieces and one end of the connecting piece in a third direction perpendicular to the first direction and the second direction, The enclosed space is formed by a space surrounded by the pair of opposing pieces, the connecting piece, and the bottom piece. heating device.

5. The heating device according to claim 4, the fixing member has a pressing portion formed so as to extend in a direction perpendicular to the first direction from the other end portions of the pair of opposing pieces in the first direction and the other end portion of the bottom piece in the first direction, The ceramic heater is fixed by the fixing member when the pressing portion abuts against the flange portion. heating device.

6. The heating device according to claim 5, the fixing member has one end that opens to the connecting piece and a cylindrical inlet passage portion that extends in a direction opposite to the enclosed space, The base portion disposed in the enclosed space is connected to one end of the inlet passage portion, thereby communicating an internal space of the inlet passage portion with an internal space of the base. heating device.

7. The heating device according to claim 3, The housing has a third space defined by the first space, a control board for controlling the supply of electricity to the resistance heating element is disposed in the third space; the first conductive member and the second conductive member extend from the first electrode and the second electrode toward the control board, respectively, and have their respective tip ends connected to the control board; heating device.

8. The heating device according to claim 7, The housing has an outlet passage formed therein for allowing the medium to flow out of the first space, a first temperature sensor that detects the temperature of a medium flowing through the inlet passage portion, and a second temperature sensor that detects the temperature of a medium flowing through the outlet passage portion, a signal representing the temperature detected by the first temperature sensor and a signal representing the temperature detected by the second temperature sensor are transmitted to the control board; heating device.

9. The heating device according to claim 3, The sealing member is a potting agent containing, as a main component, any one of an olefin-based resin, an epoxy-based resin, and a silyl group-containing special polymer. heating device.

10. 10. The heating device according to claim 1, A heating device used to heat a medium flowing through a flow path formed in a device mounted on a vehicle.

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