WO2023095517A1 - Heat medium heating device - Google Patents

Abstract

[Problem] To provide a heat medium heating device which can suppress heating components, such as a transistor, from being overheated while suppressing an increase in manufacturing costs. [Solution] This heat medium heating device includes: a heater which generates heat due to energization and heats a heat medium inside a housing; and a control board 4 on which a heater control circuit for controlling the energization of the heater is mounted, and which is screwed and fixed to the housing. Formed on the control board 4 are first to third heat transfer patterns 51-53 that extend from the vicinity of heating components (first IGBT 31, second IGBT 32, and voltage dividing resistors R3, R4) constituting the heater control circuit toward a through-hole 41, which is a screw fixing section.

Description

Heat medium heating device

The present invention relates to a heat medium heating device that heats a heat medium.

A liquid heating device described in Patent Document 1 is known as an example of a heat medium heating device. The liquid heating device described in Patent Document 1 includes a tank that stores a liquid heat medium, an electric heater that heats the liquid heat medium in the tank, and a transistor that controls current supplied to the electric heater. and the tank has a heat radiating portion for radiating the heat of the transistor to the liquid heat medium.

JP 2015-137784 A

In the liquid heating device described in Patent Document 1, since the tank is provided with the heat radiating portion for radiating the heat of the transistor, the shape of the tank becomes large and/or complicated, which makes the manufacturing of the device difficult. Costs may increase.

Therefore, an object of the present invention is to provide a heat medium heating device capable of suppressing overheating of heat-generating components such as transistors while suppressing an increase in manufacturing costs.

According to one aspect of the present invention, a housing, a heater that generates heat when energized to heat a heat medium in the housing, and a heater control circuit that controls energization to the heater are mounted and screwed to the housing. A heat medium heating device including a control board is provided. In this heat medium heating device, the control board is provided with a heat conducting portion extending from the vicinity of at least one heat-generating component constituting the heater control circuit toward the screwing portion.

According to the present invention, it is possible to provide a heat medium heating device capable of suppressing overheating of heat-generating components such as transistors while suppressing an increase in manufacturing costs.

1 is a diagram conceptually showing an in-vehicle heating device to which a heat medium heating device according to an embodiment is applied; FIG. FIG. 3 is a diagram showing a configuration example of a heater control circuit that controls energization to the heater of the heat medium heating device according to the embodiment; 1 is a schematic top view of an example of a heat medium heating device according to an embodiment; FIG. FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3; 4 is a cross-sectional view taken along the line BB of FIG. 3; FIG. 4 is a cross-sectional view taken along line CC of FIG. 3; FIG. FIG. 7 is a cross-sectional view taken along line DD of FIG. 6; FIG. 4A is a schematic top view of the control board, and FIG. 4B is a schematic bottom view of the control board. FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 conceptually shows an in-vehicle heating device 10 to which a heat medium heating device 1 according to one embodiment of the present invention is applied. The vehicle-mounted heating device 10 shown in FIG. Water (including water mixed with antifreeze or the like) is usually used as the heat medium. Therefore, the heat medium heating device 1 is also called a water heating device.

The heat medium heating device 1 is provided at the first position of the heat medium circulation path 11 . The heat medium heating device 1 has a heater 3 that generates heat when energized, and is configured to heat the heat medium flowing through the heat medium circulation path 11 . Specifically, the heat medium heating device 1 heats a heat medium that has flowed in from an inflow portion (an inflow port 23, which will be described later) by the heater 3, and the heated heat medium flows out from an outflow portion (an outflow port 24, which will be described later). It is configured to allow Although not particularly limited, in the present embodiment, the heater 3 is composed of a pair of heaters (first heater 3A and second heater 3B) electrically connected in parallel. Note that the heat medium heating device 1 will be described in detail later.

A heat exchanger 12 is provided at the second position of the heat medium circuit 11 . The heat exchanger 12 is arranged in a ventilation duct 13 that blows air for air conditioning into the vehicle interior, and generates air for heating the vehicle interior by heat exchange between the heat medium heated by the heat medium heating device 1 and the air. A bypass passage 14 bypassing the heat exchanger 12 is provided in the ventilation duct 13 , and an air mix damper 15 controls the flow of air in the ventilation duct 13 .

FIG. 2 is a diagram showing one configuration example of the heater control circuit 30 that controls the energization of the heaters 3 (the first heater 3A and the second heater 3B).

In this embodiment, the heater control circuit 30 is configured to apply the voltage of the high voltage power supply to the heater 3 .

Referring to FIG. 2, in the heater control circuit 30, a first IGBT (insulated gate bipolar transistor) 31 as a switching element is provided on the output side (voltage side) of the high voltage power supply from the heater 3. A second IGBT 32 is provided as a switching element on the ground side of the high voltage power supply. The first and second IGBTs 31 and 32 can be turned ON/OFF according to signals input to their gates. Two output terminals of an IGBT driver 33 are connected to the gates of the first and second IGBTs 31 and 32, respectively.

The IGBT driver 33 has two input terminals and two output terminals, and can individually turn on/off the first and second IGBTs 31 and 32 by output signals corresponding to the input signals. is. Two output terminals of a microcomputer (CPU) 34 are connected to two input terminals of the IGBT driver 33, respectively.

The microcomputer 34 generates a command signal for the IGBT driver 33 mainly based on the heating request. Specifically, the microcomputer 34 sets the ratio of the ON time of the heater 3 based on the heating request, generates a PWM signal corresponding to the set ON time, and outputs the PWM signal to the IGBT driver 33 . That is, the microcomputer 34 controls the ratio of the ON time of the first and second IGBT transistors 31 and 32 via the IGBT driver 33, thereby controlling the temperature of the heater 3 and the heat generated by the heater 3. Control the temperature of the medium.

Detection results of various detection units (first temperature detection unit 35, second temperature detection unit 36, voltage detection unit 37, current detection unit 38) are input to the microcomputer 34 for overheat protection.

The first temperature detection unit 35 detects temperatures of the first and second IGBTs 31 and 32 . The first temperature detection unit 35 includes a first thermistor Th1 arranged near the first and second IGBTs 31 and 32 . Specifically, in the present embodiment, the first temperature detection unit 35 includes a resistor R1 and a first It includes a thermistor Th1 and is configured to output the terminal voltage V1 of the first thermistor Th1 to the microcomputer 34 as the temperature equivalent voltage of the first and second IGBTs 31 and 32 .

The second temperature detection unit 36 detects the temperature of the heater 3 (including the temperature of the heat medium heated by the heater 3). The second temperature detection unit 36 includes a second thermistor Th2 arranged near the heater 3 . Specifically, in the present embodiment, the second temperature detection unit 36 includes a resistor R2 and a second thermistor Th2 connected in series between a constant voltage power supply (denoted as "5 V" in the drawing) and the ground. It is configured to output the terminal voltage V2 of the second thermistor Th2 to the microcomputer 34 as the voltage corresponding to the temperature of the heater 3 .

A voltage detection unit 37 detects the voltage applied to the heater 3 . In this embodiment, the voltage detection unit 37 includes voltage dividing resistors R3 and R4 connected in series between the output side (voltage side) of the high voltage power supply and the ground side, and the terminal voltage of the ground side resistor R4 is V3 is configured to be output to the microcomputer 34 as a value equivalent to the voltage applied to the heater 3 .

The current detection unit 38 detects currents flowing through the first IGBT 31 , the second IGBT 32 and the heater 3 . In this embodiment, the current detection unit 38 includes a resistor R5 provided between the second IGBT 32 and the ground side of the high-voltage power supply, and an operational amplifier OP that detects a potential difference ΔV across the resistor R5. The potential difference ΔV detected by the OP is output to the microcomputer 34 as a current equivalent value flowing through the first IGBT 31 , the second IGBT 32 and the heater 3 .

The microcomputer 34 detects the temperatures of the first and second IGBTs 31 and 32 based on the terminal voltage V1 of the first thermistor Th1 input from the first temperature detection unit 35, 2 The temperature of the heater 3 is detected based on the terminal voltage V2 of the thermistor Th2, and the voltage applied to the heater 3 is detected based on the terminal voltage V3 of the resistor R4 input from the voltage detection unit 37. Further, the microcomputer 34 detects the current (=ΔV /R5).

Then, the microcomputer 34 detects when the temperature of the first and second IGBTs 31 and 32 exceeds a predetermined value, when the temperature of the heater 3 exceeds a predetermined value, and when the voltage applied to the heater 3 exceeds a predetermined value. or when the current flowing through the first IGBT 31 , the second IGBT 32 and the heater 3 exceeds a predetermined value, a forced OFF signal is output to the IGBT driver 33 . In other words, the microcomputer 34 stops outputting the PWM signal to the IGBT driver 33 . As a result, the first and second IGBTs 31 and 32 are forcibly turned OFF, and power supply to the heater 3 is stopped. As a result, it is possible to protect the first and second IGBTs 31 and 32 and the heater 3 from overheating.

Next, the heat medium heating device 1 will be described with reference to FIGS. 3 to 7. FIG. 3 is a schematic top view of an example of the heat medium heating device 1, FIG. 4 is a cross-sectional view along line AA in FIG. 3, and FIG. 5 is a schematic cross-sectional view along line BB in FIG. 6 is a CC sectional view of FIG. 3, and FIG. 7 is a DD sectional view of FIG.

The heat medium heating device 1 has a housing 2 . The housing 2 is constructed by integrally fastening a plurality of housing members (here, a first housing member 2A, a second housing member 2B, and a third housing portion 2C) with bolts (not shown) or the like.

The housing 2 has therein a heater accommodation chamber 21 that accommodates the heaters 3 (the first heater 3A and the second heater 3B) and a board accommodation chamber 22 that accommodates the control board 4 on which the heater control circuit 30 is mounted. In this embodiment, the heater accommodation chamber 21 is formed by fastening the first housing member 2A and the second housing member 2B together, and the substrate accommodation chamber 22 is formed by joining the first housing member 2A and the second housing member 2B. is formed by further fastening the third housing member 2C to the fastening body.

The heater accommodation chamber 21 includes a first accommodation portion 21A, a second accommodation portion 21B, and a communication portion 21C that communicates the first accommodation portion 21A and the second accommodation portion 21B. 21 A of 1st accommodating parts and the 2nd accommodating part 21B are provided in parallel, 21 C of communication parts connect these between 21 A of 1st accommodating parts, and the 2nd accommodating part 21B. The first heater 3A is accommodated in the first accommodation portion 21A, and the second heater 3B is accommodated in the second accommodation portion 21B.

In this embodiment, the first heater 3A and the second heater 3B have a substantially cylindrical outer shape. The first housing portion 21A and the second housing portion 21B are formed as substantially cylindrical spaces having a larger diameter than the first heater 3A and the second heater 3B. Therefore, a first annular space is formed between the inner surface of the first accommodating portion 21A and the outer surface of the first heater 3A, and a second annular space is formed between the inner surface of the second accommodating portion 21B and the outer surface of the second heater 3B. An annular space is formed. These first and second annular spaces communicate with each other through a communicating portion 21C.

In addition, the housing 2 has an inlet 23 through which the heat medium flows into the heater housing chamber 21 and an outlet 24 through which the heat medium flows out of the heater housing chamber 21 . The inflow port 23 is formed to allow the heat medium to flow into one side of the heater housing chamber 21 (first housing portion 21A) in the longitudinal direction, and the outflow port 24 is formed in the heater housing chamber 21 (first housing portion 21A). It is formed so that the heat medium flows out from the other side in the longitudinal direction. In this embodiment, the inlet 23 and the outlet 24 are provided on the same side surface of the housing 2 . However, it is not limited to this, and the inflow port 23 and the outflow port 24 may be formed on different sides of the housing 2 .

The heater housing chamber 21 , the inlet 23 and the outlet 24 constitute a heat medium flow path within the housing 2 , and this heat medium flow path constitutes a part of the heat medium circulation path 11 . That is, the heat medium flowing through the heat medium circulation path 11 flows into the heater housing chamber 21 through the inlet 23 , flows through the heater housing chamber 21 , and then flows out of the heater housing chamber 21 through the outlet 24 . It has become. When the heat medium flows through the heater housing chamber 21, more specifically, when it mainly flows through the first annular space and the second annular space, the heater 3 (the first heater 3A and the second heater 3B) heated.

The substrate storage chamber 22 is provided adjacent to the heater storage chamber 21 with the wall portion 25 interposed therebetween. Specifically, in the housing 2 , the board storage chamber 22 is separated from the heater storage chamber 21 by a wall portion 25 , and the heater storage chamber 21 is arranged on one side (lower side) of the wall portion 25 , and the wall A substrate receiving chamber 22 is arranged on the other side (upper side) of the portion 25 . In other words, the wall portion 25 defines a portion of the heater housing chamber 21 and a portion of the substrate housing chamber 22 .

A plurality of (here, four) board mounting portions 26 for mounting the control board 4 are provided in the board housing chamber 22 . In this embodiment, the plurality of board mounting portions 26 are provided on the wall portion 25 . Specifically, each of the plurality of board mounting portions 26 is formed in a boss shape protruding from the wall portion 25 to the other side (upper side), and a screw hole (not shown) is formed on the upper surface.

Here, the control board 4 will be explained. FIG. 8 shows an example of the control board 4. As shown in FIG. 8A is a schematic top view of the control board 4, and FIG. 8B is a schematic bottom view of the control board 4. FIG. As described above, the heater control circuit 30 is mounted on the control board 4. FIGS. Only heat generating components that generate relatively large amounts of heat, specifically the first IGBT 31, the second IGBT 32, the voltage dividing resistor R3 and the voltage dividing resistor R4 are shown.

A plurality of (that is, four) screw insertion holes 41 corresponding to the plurality of board mounting portions 26 are formed in the control board 4 . In this embodiment, the control board 4 is formed in a substantially rectangular shape when viewed from above, and screw insertion holes 41 are formed in the vicinity of each of its four corners. In the control board 4, the fixing screws 5 (see FIGS. 4 to 6) inserted through the plurality of screw insertion holes 41 are screwed into the corresponding screw holes formed on the upper surface of the board mounting portion 26. By fitting together, they are fixed (screwed) to the upper surfaces of the plurality of substrate mounting portions 26 .

In this embodiment, the first IGBT 31 and the second IGBT 32 are mounted on the lower surface of the control board 4, that is, the surface on the heater housing chamber 21 side. That is, the first IGBT 31 and the second IGBT 32 are arranged on the lower surface side of the control board 4, and their leads (not shown) are connected to circuit patterns (not shown) formed on the control board 4. . Preferably, the first IGBT 31 and the second IGBT 32 are arranged at positions on the control board 4 on the side of the inlet 23 (positions closer to the inlet 23 than the outlet 24) when viewed from above. 8A and 8B, reference numeral 42 denotes a lead insertion hole into which the lead of the first IGBT 31 is inserted, and reference numeral 43 denotes a lead into which the lead of the second IGBT 32 is inserted. It shows an insertion hole.

On the other hand, the voltage dividing resistor R3 and the voltage dividing resistor R4 are mounted on the upper surface of the control board 4. That is, the voltage dividing resistor R3 and the voltage dividing resistor R4 are arranged on the upper surface side of the control board 4, and their leads (not shown) are connected to circuit patterns (not shown) formed on the control board 4. However, the present invention is not limited to this, and the voltage dividing resistor R3 and the voltage dividing resistor R4 may be mounted on the lower surface of the control board 4 in the same manner as the first IGBT31 and the second IGBT32.

By the way, if the heat-generating parts are in an overheated state or a state close to it, the desired performance cannot be obtained. As a countermeasure against overheating of heat-generating components, it is common to dissipate the heat generated by heat-generating components by using heat sinks or heat sinks. It costs a minute. Therefore, in this embodiment, the increase in cost is suppressed by taking the following measures for the control board 4 .

In the present embodiment, on the control board 4, there is a heat conducting element extending from the heat-generating component or its vicinity (hereinafter simply referred to as "the vicinity of the heat-generating component") to one of the plurality of screw insertion holes 41, that is, toward the screwing portion. department is provided. The heat conducting part is not particularly limited as long as its heat conductivity is higher than that of the main body of the control board 4 . For example, the heat-conducting portion may be a heat-conducting pattern formed on the control substrate 4 by etching or the like, similar to the circuit pattern. In this case, the thermally conductive pattern may be formed of the same material as the circuit pattern (eg, copper foil), but does not form an electrical circuit (ie, is configured not to carry current).

Specifically, in the present embodiment, on the control board 4 , a first IGBT 31 extending from the vicinity of the first IGBT 31 toward the screw insertion hole 41 closest to the first IGBT 31 among the plurality of screw insertion holes 41 is provided. A thermally conductive pattern 51 is formed as a thermally conductive portion. The first heat conductive pattern 51 is made of the same material as the circuit pattern, and extends to a position separated from the screw insertion hole 41 by an insulating distance. The first heat conduction pattern 51 includes a bottom side first heat conduction pattern 51A formed on the bottom surface of the control board 4, that is, on the same surface as the surface of the control board 4 on which the first IGBTs 31 are mounted. 4, that is, on the surface opposite to the surface of the control board 4 on which the first IGBTs 31 are mounted.

When the control board 4 is attached to the board attachment portion 26 , the vicinity of the screw insertion hole 41 on the bottom surface of the control board 4 contacts the top surface of the board attachment portion 26 . The substrate mounting portion 26 is a part of the housing 2 and its temperature is lower than that of the heated first IGBT 31 . In particular, in the present embodiment, the board mounting portion 26 is formed so as to protrude from the wall portion 25 that defines a part of the heater accommodation chamber 21 , and the heater accommodation chamber 21 is one of the heat medium flow paths in the housing 2 . make up the department. Therefore, the heat medium flowing through the heater housing chamber 21 can maintain the temperature of the substrate mounting portion 26 sufficiently lower than that of the heated first IGBT 31 .

Therefore, the heat generated by the first IGBT 31 is transferred to the vicinity of the screw insertion hole 41 by the first heat conduction pattern 51 (the first heat conduction pattern 51A on the lower surface and the first heat conduction pattern 51B on the upper surface), From there, the heat can be further transferred to the board mounting portion 26 (housing 2) and the heat medium. That is, the heat generated by the first IGBT 31 can be dissipated in the order of the first thermal conductive pattern 51→the board mounting portion 26 (housing 2)→the heat medium. Therefore, the first IGBT 31 and its periphery are prevented from being overheated.

Further, on the control board 4, a second heat conduction pattern 52 extending from the vicinity of the second IGBT 32 toward the screw insertion hole 41 closest to the second IGBT 32 among the plurality of screw insertion holes 41 is a heat conduction portion. is formed as Like the first heat conduction pattern 51, the second heat conduction pattern 52 is made of the same material as the circuit pattern, and extends to a position separated from the screw insertion hole 41 by an insulating distance. The second heat conduction pattern 52 includes a bottom side second heat conduction pattern 52A formed on the bottom surface of the control substrate 4, that is, on the same surface as the surface of the control substrate 4 on which the second IGBTs 32 are mounted, and the control substrate. 4, that is, on the surface opposite to the surface of the control board 4 on which the second IGBTs 32 are mounted.

Therefore, as in the case of the first IGBT 31, the heat generated by the second IGBT 32 is dissipated by the second heat conduction pattern 52 (the second heat conduction pattern 52A on the lower surface and the second heat conduction pattern 52B on the upper surface). The heat can be transferred to the vicinity of the insertion hole 41 and from there to the substrate mounting portion 26 (housing 2) and the heat medium. In other words, the heat generated by the second IGBT 32 can be dissipated like the second heat conduction pattern 52→the board mounting portion 27 (housing 2)→the heat medium, and the second IGBT 32 and its surroundings can be overheated. Suppressed.

Further, on the control board 4, from the vicinity of the voltage dividing resistor R3 and the voltage dividing resistor R4, it extends toward the screw insertion hole 41 closest to the voltage dividing resistor R3 and the voltage dividing resistor R4 among the plurality of screw insertion holes 41. A third heat conductive pattern 53 is formed. The third heat conduction pattern 53 is formed on the lower surface of the control board 4, that is, on the surface opposite to the surface of the control board 4 on which the voltage dividing resistors R3 and R4 are mounted. The third heat-conducting pattern 53 has a size that covers most of the voltage dividing resistors R3 and R4, preferably a size that includes all of the voltage dividing resistors R3 and R4. .

Therefore, as in the case of the first and second IGBTs 31 and 32, the heat generated by the voltage dividing resistor R3 and the voltage dividing resistor R4 is transferred to the vicinity of the screw insertion hole 41 by the third heat conduction pattern 53. from which the heat can be further transferred to the board mounting part 26 (housing 2) and the heat medium. That is, the heat generated by the voltage dividing resistor R3 and the voltage dividing resistor R4 can be released through the third heat conduction pattern 53→the board mounting portion 27 (housing 2)→the heat medium, and the voltage dividing resistor R3, the voltage dividing resistor R4, and the Overheating of the surrounding area is suppressed.

According to the heat medium heating device 1 according to the embodiment, the following effects can be obtained.

In the heat medium heating device 1 according to the embodiment, the control board 4 on which the heater control circuit 30 is mounted is screwed to a plurality of board mounting portions 26 that are part of the housing 2 . Further, on the control board 4, from the vicinity of the heat-generating components (the first IGBT 31, the second IGBT 32, the voltage dividing resistor R3, and the voltage dividing resistor R4) among the plurality of electronic components constituting the heater control circuit 30, A heat conducting portion (first heat conducting pattern 51, second heat conducting pattern 52, and third heat conducting pattern 53) extending toward the screwing portion (screw insertion hole 41) is provided. Furthermore, the plurality of board mounting portions 26 are provided on a wall portion 25 that defines a portion of the heater accommodation chamber 21 that constitutes a portion of the heat medium flow path in the housing 2 . Therefore, the heat generated by the heat-generating component can be transferred by the heat-conducting portion to the vicinity of the screw insertion hole 41, and further heat-transferred from there to the board mounting portion 26 (housing 2) and the heat medium. Therefore, overheating of the heat-generating component and its surroundings is suppressed. Moreover, conventionally, only the control board 4 needs to be changed, and there is no need to add parts or change the shape of the housing 2 . Therefore, an increase in manufacturing cost is also suppressed.

In the above-described embodiment, the first thermally conductive pattern 51 includes the first lower thermally conductive pattern 51A and the first upper thermally conductive pattern 51B. However, the first heat conduction pattern 51 is not limited to this, and may be composed of either the bottom side first heat conduction pattern 51A or the top side first heat conduction pattern 51B. Similarly, the second heat-conducting pattern 52 may be composed of either the bottom-side second heat-conducting pattern 52A or the top-side second heat-conducting pattern 52B.

Also, in the above-described embodiment, the first to third heat conductive patterns 51 to 53 are made of the same material as the circuit pattern (that is, conductive material). However, the present invention is not limited to this, and the first to third heat conductive patterns may be made of a material different from that of the circuit pattern. Note that when the first to third heat conduction patterns are formed of a non-conductive material, the first heat conduction pattern 51 is formed to extend from the vicinity of the first IGBT 31 to the screw insertion hole 41, and the second heat conduction pattern The pattern 52 is formed to extend from the vicinity of the second IGBT 32 to the screw insertion hole 41, and the third heat conduction pattern 53 extends from the vicinity of the voltage dividing resistors R3 and R4 to the screw insertion hole 41. can be formed as

Further, in the above-described embodiment, the heater 3 is composed of a pair of heaters (the first heater 3A and the second heater 3B), and the first heater 3A and the second heater 3B have substantially cylindrical outer shapes. there is However, it is not limited to this. The heater 3 may have any number and shape as long as it generates heat when energized to heat the heat medium.

Although further detailed description is omitted, the leads of the first IGBT 31 and the leads of the second IGBT 32 may be extended to bring the first IGBT 31 and the second IGBT 32 closer to or in contact with the wall portion 25 . By doing so, it is possible to more effectively suppress the overheating of the first IGBT 31 and the second IGBT 32 .

Although the embodiments and some modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications, and further modifications and changes can be made based on the technical idea of the present invention. is of course possible.

DESCRIPTION OF SYMBOLS 1...Heat-medium heating apparatus 2...Housing 3...Heater 3A...First heater 3B...Second heater 4...Control board 5...Heat conduction part 21...Heater accommodation chamber 22...Substrate accommodation chamber, 25 Wall portion 26 Substrate mounting portion 30 Heater control circuit 31 First IGBT (heat generating component) 32 Second IGBT (heat generating component) 51 First heat conduction pattern (heat conduction portion ), 52... Second heat conduction pattern (heat conduction part), 53... Third heat conduction pattern (heat conduction part), R3, R4... Voltage dividing resistor (heat generating component)

Claims (5)

1. A heat medium heater including a housing, a heater that generates heat when energized to heat a heat medium within the housing, and a control board that is mounted with a heater control circuit that controls energization of the heater and is screwed to the housing. a device,
   A heat medium heating device, wherein a heat conducting portion extending from the vicinity of at least one heat-generating component constituting the heater control circuit toward a screwing portion is provided on the control board.
2. The housing has a heater accommodating chamber that accommodates the heater and forms part of the heat medium flow path, and a plurality of substrate mounting portions that are provided on a wall portion that defines part of the heater accommodating chamber. ,
   The control board is screwed to the plurality of board mounting portions,
   The heat medium heating device according to claim 1.
3. The heat medium heating device according to claim 1 or 2, wherein the heat conducting portion is provided on the same surface as the surface of the control board on which the heat generating component is mounted.
4. The heat medium heating device according to any one of claims 1 to 3, wherein the heat conducting portion is provided on the surface of the control board opposite to the surface on which the heat generating component is mounted.
5. The heat medium heating device according to claims 1 to 4, wherein the heat conducting part is a heat conducting pattern formed on the control board.

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