Vehicle heat transfer fluid heating device

Abstract

To provide a vehicle heat medium heating device capable of surely stopping power supply to a heat without occurrence of malfunction even if flooding into a housing occurs.SOLUTION: A vehicle heat medium heating device 1 includes: a heater 3 which heats a heat medium in a housing; a control board 4 on which a heater control circuit 30 is mounted; and a pair of conductive pads 6a and 6b provided on the control board 4 while being spaced apart from each other and separately from the heater control circuit 30 and having conductivity. A breaker 4e is provided in a first power line 4a from a positive electrode of an external power source B. One conductive pad 6a is electrically connected to an intermediate line 4a1 in the first power line 4a, and the other conductive pad 6b is electrically connected to a second power line 4b from a negative electrode of the external power source B. In a state where the housing is fixed in a predetermined reference posture on a vehicle, the pair of conductive pads 6a and 6b is positioned lower than circuit elements of the heater control circuit 30.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle heat medium heating device for heating a heat medium.

Background Art

[0002] As an example of a vehicle heat medium heating device, a heat medium heating device described in Patent Document 1 is known. The heat medium heating device described in Patent Document 1 includes a housing (case), a heater disposed in the housing for heating a heat medium, and a substrate disposed in the housing. A control circuit for controlling the power supplied to the heater is provided on the substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the heat medium heating device described in Patent Document 1, a control circuit for controlling the power supplied to the heater is provided on the substrate disposed in the housing. Therefore, even if water or the like enters the housing and flooding occurs, there is a problem that it is necessary to stop the power supply to the heater without malfunction.

[0005] Therefore, an object of the present invention is to provide a vehicle heat medium heating device that can surely stop the power supply to the heater without malfunction even if flooding occurs inside the housing.

Means for Solving the Problems

[0006] According to one aspect of the present invention, a vehicle heat transfer medium heating device is provided, which includes a housing, a heater that generates heat by being supplied with power from an external power source to heat a heat transfer medium within the housing, and a control board on which a heater control circuit for controlling the power supply to the heater is mounted and which is housed within the housing. The vehicle heat transfer medium heating device includes a pair of conductive pads that are electrically conductive and are provided on the control board at a distance from each other and separately from the heater control circuit. In the vehicle heat transfer medium heating device, a first power line that electrically connects one pole of the external power source to the heater control circuit is provided with a circuit breaker that cuts off the power supply when a current exceeding a predetermined value flows, one of the pair of conductive pads is electrically connected to an intermediate line between the circuit breaker and the heater control circuit in the first power line, and the other of the pair of conductive pads is electrically connected to a second power line that electrically connects the other pole of the external power source to the heater control circuit, and when the housing is fixed to the vehicle in a predetermined reference position, the pair of conductive pads are located below the circuit elements that constitute the heater control circuit. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a vehicle heat transfer medium heating device that can reliably stop the power supply to the heater without malfunctioning, even if water enters the housing. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram conceptually shows an on-board heating system to which a vehicle heat transfer medium heating device according to the embodiment is applied. [Figure 2] This figure shows an example configuration of a heater control circuit that controls the power supply to the heater of a vehicle heat transfer medium heating device according to an embodiment. [Figure 3] This is a schematic top view of an example of a vehicle heat transfer medium heating device according to an embodiment. [Figure 4] This is a cross-sectional view AA in Figure 3. [Figure 5] Figure 3 is a cross-sectional view of BB. [Figure 6] Figure 3 is a cross-sectional view of CC. [Figure 7] Figure 6 is a cross-sectional view of the DD. [Figure 8] This is a diagram showing the control board of a vehicle heat transfer medium heating device according to an embodiment. [Figure 9] This figure shows a modified example of the heater control circuit. [Figure 10] This figure shows an example of a control board on which the heater control circuit shown in Figure 9 is implemented. [Figure 11] This figure shows another modified example of the heater control circuit. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described based on the attached drawings.

[0010] Figure 1 conceptually shows an on-board heating system 10 to which a vehicle heat transfer medium heating device 1 according to one embodiment of the present invention is applied. The on-board heating system 10 shown in Figure 1 is configured such that a heat transfer medium is circulated through a heat transfer medium circulation path 11 by a pump P. Water (including water mixed with antifreeze, etc.) is usually used as the heat transfer medium. Therefore, the vehicle heat transfer medium heating device 1 is also called a water heating device.

[0011] The vehicle heat transfer medium heating device 1 is installed at the first position of the heat transfer medium circulation path 11. The vehicle heat transfer medium heating device 1 has a heater 3 that generates heat when an electric current is applied, and is configured to heat the heat transfer medium flowing through the heat transfer medium circulation path 11. Specifically, the vehicle heat transfer medium heating device 1 is configured to heat the heat transfer medium that flows in from the inlet (inlet 23, described later) with the heater 3, and to discharge the heated heat transfer medium from the outlet (outlet 24, described later). Although not particularly limited, in this embodiment the heater 3 is composed of a pair of heaters (first heater 3A and second heater 3B) that are electrically connected in parallel. The vehicle heat transfer medium heating device 1 will be described in detail later.

[0012] A heat exchanger 12 is provided at the second position of the heat medium circulation path 11. The heat exchanger 12 is disposed 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 vehicle heat medium heating device 1 and air. Note that a bypass passage 14 that bypasses the heat exchanger 12 is provided in the ventilation duct 13, and the air flow in the ventilation duct 13 is controlled by an air mix damper 15.

[0013] FIG. 2 conceptually shows a configuration example of a heater control circuit 30 that controls power supply to a heater 3 (first heater 3A and second heater 3B).

[0014] The vehicle heat medium heating device 1 has a control board 4, and the heater control circuit 30 is mounted on the control board 4. In the present embodiment, the heater control circuit 30 is configured to supply power from an external power source B, which is a high-voltage power source mounted on the vehicle, to the heater 3. That is, the heater 3 generates heat by power supply from the external power source B to heat the heat medium.

[0015] 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 positive electrode side (output side) of the external power source B with respect to the heater 3, and a second IGBT 32 as a switching element is provided on the negative electrode side (ground side) of the external power source B with respect to the heater 3. The first and second IGBTs 31 and 32 can turn on / off energization according to signals input to the gates. Two output terminals of an IGBT driver 33 are respectively connected to the gates of the first and second IGBTs 31 and 32.

[0016] The IGBT driver 33 has two input terminals and two output terminals, and can individually turn on / off and drive the first and second IGBTs 31 and 32 by output signals corresponding to the input signals. Two output terminals of a microcomputer (CPU) 34 are respectively connected to the two input terminals of the IGBT driver 33.

[0017] The microcomputer 34 mainly generates a command signal for the IGBT driver 33 based on the heating demand. Specifically, the microcomputer 34 sets the ratio of the ON time of the heater 3 based on the heating demand, generates a PWM signal corresponding to the set ON time, and outputs it 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 further the temperature of the heat medium heated by the heater 3.

[0018] Although not shown in FIG. 2, the heater control circuit 30 is provided with a first temperature detection unit for detecting the temperatures of the first and second IGBTs 31 and 32, a second temperature detection unit for detecting the temperature of the heater 3 (including the temperature of the heat medium heated by the heater 3), a voltage detection unit for detecting the voltage applied to the heater 3, a current detection unit for detecting the currents flowing through the first and second IGBTs 31 and 32 and the heater 3, etc., for overheat protection and fault detection. The detection results of these respective detection units can be input to, for example, the microcomputer 34 and used to determine the control signal to the IGBT driver 33.

[0019] For example, when the temperatures of the first and second IGBTs 31 and 32 exceed a predetermined value, when the temperature of the heater 3 exceeds a predetermined value, when the voltage applied to the heater 3 exceeds a predetermined value, or when the currents flowing through the first IGBT 31, the second IGBT 32 and the heater 3 exceed a predetermined value, the microcomputer 34 outputs a control signal for forcibly turning OFF the first and second IGBTs 31 and 32 to the IGBT driver 33. As a result, the first and second IGBTs 31 and 32 are forcibly turned OFF, and the power supply to the heater 3 is stopped. As a result, overheat protection and fault detection of the first and second IGBTs 31 and 32 and the heater 3 can be achieved.

[0020] Here, the heater control circuit 30 is connected to a first power supply line 4a and a second power supply line 4b, which constitute the power supply line from the external power supply B to the heater control circuit 30. Furthermore, the heater control circuit 30 is connected to a first heater line 4c and a second heater line 4d, which constitute the power supply line from the heater control circuit 30 to the heater 3.

[0021] The first power line 4a electrically connects one pole of the external power supply B to the heater control circuit 30 (control board 4), and the second power line 4b electrically connects the other pole of the external power supply B to the heater control circuit 30 (control board 4).

[0022] In this embodiment, the first power line 4a extends from the positive side of the external power supply B, and the second power line 4b extends from the negative side (ground side) of the external power supply B. On the control board 4, there are positive-side power line connection part 35a, negative-side power line connection part 35b, positive-side heater line connection part 35c, and negative-side heater line connection part 35d, all of which are conductive and constitute part of the circuit pattern of the heater control circuit 30. Furthermore, the positive-side power line connection part 35a and the positive-side heater line connection part 35c are connected via a positive-side wiring pattern 35e formed on the control board 4, and the negative-side power line connection part 35b and the negative-side heater line connection part 35d are connected via a negative-side wiring pattern 35f formed on the control board 4. Each of these connection points (35a, 35b, 35c, 35d) and each pattern (35e, 35f) is a circuit pattern and is part of the circuit elements that make up the heater control circuit 30.

[0023] Specifically, the first power line 4a electrically connects the positive terminal of the external power supply B to the positive terminal side power line connection part 35a, the second power line 4b electrically connects the negative terminal of the external power supply B to the negative terminal side power line connection part 35b, the first heater line 4c connects the positive terminal side heater line connection part 35c to the positive terminal side terminal of the heater 3, and the second heater line 4d connects the negative terminal side heater line connection part 35d to the negative terminal side terminal of the heater 3. In this embodiment, the second power line 4b is directly connected to the negative terminal of the external power supply B. However, it is not limited to this, and if the negative terminal of the external power supply B is connected to the vehicle body via an earth wire and grounded, the second power line 4b may be connected to the vehicle body and then connected to the negative terminal of the external power supply B via the vehicle body and the earth wire.

[0024] Next, the vehicle heat transfer medium heating device 1 will be described with reference to Figures 3 to 7. Figure 3 is a schematic top view of an example of the vehicle heat transfer medium heating device 1, Figure 4 is a cross-sectional view AA of Figure 3, Figure 5 is a schematic cross-sectional view BB of Figure 3, Figure 6 is a cross-sectional view CC of Figure 3, and Figure 7 is a cross-sectional view DD of Figure 6.

[0025] The vehicle heat transfer 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 part 2C) with bolts (not shown) or the like.

[0026] The housing 2 has a heater housing chamber 21 for housing heaters 3 (first heater 3A, second heater 3B) and a board housing chamber 22 for housing a control board 4 on which a heater control circuit 30 is mounted. In this embodiment, the heater housing chamber 21 is formed by fastening a first housing member 2A and a second housing member 2B together, and the board housing chamber 22 is formed by further fastening a third housing member 2C to the fastening between the first housing member 2A and the second housing member 2B.

[0027] The heater housing chamber 21 includes a first housing section 21A, a second housing section 21B, and a connecting section 21C that connects the first housing section 21A and the second housing section 21B. The first housing section 21A and the second housing section 21B are arranged in parallel, and the connecting section 21C connects them. The first heater 3A is housed in the first housing section 21A, and the second heater 3B is housed in the second housing section 21B.

[0028] 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 with 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 housing 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 housing portion 21B and the outer surface of the second heater 3B. These first and second annular spaces are in communication with each other via a connecting portion 21C.

[0029] Furthermore, the housing 2 has an inlet 23 for introducing a heat transfer medium into the heater chamber 21 and an outlet 24 for releasing the heat transfer medium from the heater chamber 21. The inlet 23 is formed to introduce the heat transfer medium into one longitudinal side of the heater chamber 21 (first housing section 21A), and the outlet 24 is formed to release the heat transfer medium from the other longitudinal side of the heater chamber 21 (first housing section 21A). In this embodiment, the inlet 23 and the outlet 24 are provided on the same side of the housing 2. However, it is not limited to this, and the inlet 23 and the outlet 24 may be formed on different sides of the housing 2.

[0030] The heater chamber 21, inlet 23, and outlet 24 constitute a heat transfer medium flow path within the housing 2, and this heat transfer medium flow path constitutes part of the heat transfer medium circulation path 11. In other words, the heat transfer medium flowing through the heat transfer medium circulation path 11 flows into the heater chamber 21 via the inlet 23, flows through the heater chamber 21, and then flows out of the heater chamber 21 via the outlet 24. The heat transfer medium is heated by the heater 3 (first heater 3A, second heater 3B) as it flows through the heater chamber 21, or more specifically, as it flows mainly through the first annular space and the second annular space.

[0031] The circuit board housing chamber 22 is located adjacent to the heater housing chamber 21, separated by a wall 25. Specifically, within the housing 2, the circuit board housing chamber 22 is separated from the heater housing chamber 21 by a wall 25, with the heater housing chamber 21 located on one side (lower side) of the wall 25 and the circuit board housing chamber 22 located on the other side (upper side) of the wall 25. The circuit board housing chamber 22 is provided with multiple (four in this case) circuit board mounting sections 26 for mounting the control board 4.

[0032] Although not shown in the figure, sealing members are provided between the first housing member 2A and the second housing member 2B, between the first housing member 2A and the third housing member 2C, and between the second housing member 2B and the third housing member 2C. These sealing members fasten adjacent housing members together in an airtight and liquid-tight manner. Furthermore, although not shown in the figure, the power supply lines from the external power source B to the heater control circuit 30 (first power line 4a and second power line 4b) and the power supply lines from the heater control circuit 30 to the heater 3 (first heater line 4c and second heater line 4d) extend through the wall of the housing 2 in an airtight and liquid-tight manner. In other words, sealing members are also provided between the through-holes for the power supply lines in the housing 2 and the power supply line portions. Therefore, the housing 2 has a structure that can prevent water from entering the inside of the substrate housing chamber 22, that is, to prevent water from entering the substrate housing chamber 22.

[0033] As described above, the vehicle heat transfer medium heating device 1 comprises a housing 2, a heater 3 that generates heat from power supplied from an external power source B to heat the heat transfer medium inside the housing 2, and a control board 4 on which a heater control circuit 30 that controls the power supply to the heater 3 is mounted and which is housed inside the housing 2.

[0034] Here, we will describe the control board 4 in detail. Figure 8 shows an example of the control board 4. As mentioned above, the heater control circuit 30 is mounted on the control board 4, but Figure 8 shows only the first IGBT 31, the second IGBT 32, the IGBT driver 33, the microcontroller 34, the positive side power line connection 35a, the negative side power line connection 35b, the positive side heater line connection 35c, and the negative side heater line connection 35d, which are the circuit elements including the electronic components and circuit patterns that make up the heater control circuit 30.

[0035] The control board 4 has multiple (i.e., four) screw insertion holes 41 that correspond to multiple board mounting portions 26. In this embodiment, the control board 4 is formed in a substantially rectangular shape in plan view, and screw insertion holes 41 are formed near each of its four corners. The control board 4 is then fixed (screwed) to the upper surfaces of the multiple board mounting portions 26 by screwing fixing screws 5 (see Figures 4 to 6), which are inserted through each of the multiple screw insertion holes 41, into screw holes formed on the upper surfaces of the corresponding board mounting portions 26.

[0036] Incidentally, while the housing 2 has a structure that can prevent water from entering the substrate housing chamber 22, if the sealing member deteriorates due to aging or other reasons, the desired sealing performance may not be achieved, and water may enter the substrate housing chamber 22. If water or other liquid enters the substrate housing chamber 22, there is a risk that an unintended current path (high current path) may be formed in the heater control circuit 30 (control board 4) through the infiltrated liquid. In this case, some of the electronic components constituting the heater control circuit 30 may be located on the current path formed by the water ingress, resulting in unintended high voltage being applied to the electronic components or high current flowing through them. As a result, the heater control circuit 30's intended overheat protection and fault detection may not be properly executed, and there is a risk that control will continue in a malfunctioning state (in other words, an ambiguous / unstable state in which the intended control does not function satisfactorily). Therefore, in this embodiment, the control board 4 is provided with the following countermeasures so that even if water enters the housing 2, the power supply to the heater 3 will be stopped without malfunction.

[0037] Referring to Figures 2 and 8, the vehicle heat transfer medium heating device 1 includes a pair of conductive pads 6a and 6b that are spaced apart from each other on the control board 4 and separate from the heater control circuit 30, and are electrically conductive. The first power line 4a extending from the external power supply B is provided with a circuit breaker 4e that cuts off the power supply when a current exceeding a predetermined value flows through it. Although not particularly limited, in this embodiment the circuit breaker 4e is composed of a fuse that melts when a current exceeding a predetermined value flows through it.

[0038] One of the pair of conductive pads 6a and 6b (hereinafter referred to as the first conductive pad 6a as appropriate) is electrically connected to the intermediate line 4a1 between the circuit breaker 4e and the heater control circuit 30 in the first power supply line 4a via the first branch line 4f. In this embodiment, the first conductive pad 6a is connected to the positive electrode of the external power supply B via the first branch line 4f and the first power supply line 4a. Therefore, the first conductive pad 6a is also called a high-voltage positive electrode pad.

[0039] The other of the pair of conductive pads (hereinafter referred to as the second conductive pad 6b as appropriate) is electrically connected to the second power supply line 4b via the second branch line 4g. In this embodiment, the second conductive pad 6b is connected to the negative electrode of the external power supply B via the second branch line 4g and the second power supply line 4b. Therefore, the second conductive pad 6b is also called the high-voltage negative electrode pad.

[0040] The first conductive pad 6a and the second conductive pad 6b may be conductive patterns formed on the control substrate 4 by etching or the like, similar to the circuit pattern of the heater control circuit 30. In this case, the first conductive pad 6a and the second conductive pad 6b may be formed from the same material as the circuit pattern (e.g., copper foil), but they do not constitute the original electrical circuit of the heater control circuit 30. The first conductive pad 6a and the second conductive pad 6b are exposed on the control substrate 4 and are separated from each other by a predetermined insulating distance.

[0041] Here, the vehicle heat transfer medium heating device 1 is mounted in the required space in the vehicle, and the orientation of the housing 2 when mounted in the vehicle is often predetermined according to the vehicle's specifications. Hereafter, this predetermined orientation of the housing 2 will be referred to as the predetermined reference orientation. The housing 2 can then be fixed to the vehicle in the predetermined reference orientation. Although not particularly limited, in this embodiment, when the housing 2 is fixed to the vehicle in the predetermined reference orientation, the control board 4 takes an upright or inclined position relative to the vertical (gravity direction). Therefore, when water enters the board housing chamber 22 and the water level gradually rises, the lower edge of the rectangular control board 4 is the first to be submerged in the liquid.

[0042] The pair of conductive pads 6a and 6b are located below the circuit elements, including the electronic components and circuit patterns that constitute the heater control circuit 30, when the housing 2 is fixed to the vehicle in the predetermined reference position. Therefore, on the control board 4, the circuit elements that constitute the heater control circuit 30 (such as the first IGBT 31, the second IGBT 32, the IGBT driver 33, the microcontroller 34, the first temperature detection unit, the second temperature detection unit, the voltage detection unit, the current detection unit, the positive side power line connection part 35a, the negative side power line connection part 35b, the positive side heater line connection part 35c, the negative side heater line connection part 35d, the positive side wiring pattern 35e, and the negative side wiring pattern 35f) are not located in the gap (space) between the pair of conductive pads 6a and 6b or below the pair of conductive pads 6a and 6b. In other words, within the housing 2 in the predetermined reference position, the circuit elements of the heater control circuit 30 are located above the pair of conductive pads 6a and 6b.

[0043] In this embodiment, the pair of conductive pads 6a and 6b are provided near the edge of the control board 4. As described above, for example, the control board 4 is formed in a substantially rectangular shape in plan view. And, for example, in the predetermined reference orientation, the edges of the control board 4 corresponding to the pair of conductive pads 6a and 6b extend in a direction perpendicular to the vertical direction (i.e., the horizontal direction). Also, for example, the pair of conductive pads 6a and 6b are provided near the longitudinal center of the edge corresponding to the lower side of the four sides of the control board 4 in the predetermined reference orientation. In this embodiment, the pair of conductive pads 6a and 6b are spaced apart from each other in the longitudinal direction (here, the horizontal direction) of the edge corresponding to the lower side.

[0044] Next, the operation of the vehicle heat transfer medium heating device 1 according to this embodiment will be explained using the case where water ingress occurs into the housing 2 (substrate housing chamber 22) as an example.

[0045] In the vehicle heat transfer medium heating device 1, when a liquid such as water gradually enters the substrate housing chamber 22, the water level in the substrate housing chamber 22 gradually rises. Let's assume that the water level in the substrate housing chamber 22 exceeds the lower edge of the control board 4 housed in the substrate housing chamber 22, and then reaches a position (a predetermined water level) corresponding to the pair of conductive pads 6a and 6b. At this time, the gap (space) between the pair of conductive pads 6a and 6b is filled with the invading liquid, intentionally creating a short circuit between the pair of conductive pads 6a and 6b. As a result, a current exceeding a predetermined value flows through the circuit breaker 4e, and the power supply from the external power source B is cut off by the circuit breaker 4e. In other words, the pair of conductive pads 6a and 6b can be said to be functioning as a water ingress detection sensor (or water leakage detection sensor).

[0046] Furthermore, even if the water level rises to the portion of the circuit elements constituting the heater control circuit 30 after the power supply is cut off by the circuit breaker 4e, the power supply to the heater control circuit 30 has already been cut off. Therefore, a short circuit will not be formed between the circuit elements of the heater control circuit 30, and as a result, it is prevented that high voltage will not be applied or large currents will not flow between unintended circuit elements.

[0047] In the vehicle heat transfer medium heating device 1 according to this embodiment, the first conductive pad 6a and the second conductive pad 6b, which are provided separately from the heater control circuit 30 and are conductive, on the control board 4 at a distance from each other, are located below the circuit elements constituting the heater control circuit 30 when the housing 2 is fixed to the vehicle in a predetermined reference position. As a result, even if water enters the housing 2 (board housing chamber 22), a short circuit can be intentionally formed between the first conductive pad 6a and the second conductive pad 6b before liquid such as water reaches the circuit elements of the heater control circuit 30. Then, by flowing a large current through this intentionally formed short circuit, the circuit breaker 4e can quickly shut off the power supply from the external power source B. Therefore, when water enters the housing 2, a short circuit is formed between the circuit elements of the heater control circuit 30, preventing high voltage from being applied or large current from flowing between unintended circuit elements. Therefore, in the event of water ingress into the housing 2, the heater control circuit 30's intended overheat protection and fault detection functions will not be properly executed, and the system will not continue operating in a malfunctioning state. This ensures that the vehicle heat transfer medium heating device 1 can reliably stop the power supply to the heater 3 without malfunctioning, even if water ingress into the housing 2.

[0048] In this embodiment, a pair of conductive pads 6a and 6b are provided near the edge of the control board 4. This allows for a wide mounting area for the heater control circuit 30 on the control board 4, while also enabling a quick shutdown of the power supply to the heater 3 in the event of water ingress.

[0049] Incidentally, if the vehicle specifications are changed, the housing 2, while fixed to the vehicle, may take a different position from the predetermined reference position that was originally planned. In such a case, when the housing 2 is fixed to the vehicle in a position different from the predetermined reference position, the pair of conductive pads 6a and 6b may not be located below the circuit elements that constitute the heater control circuit 30. If such a situation is anticipated, the vehicle heat transfer medium heating device 1 may be provided with a pair of spare conductive pads 7a and 7b in addition to the pair of conductive pads 6a and 6b, as shown in the modified examples in Figures 9 and 10 below.

[0050] Figure 9 shows a modified example of the heater control circuit 30, and Figure 10 shows an example of a control board 4 on which the heater control circuit 30 shown in Figure 9 is mounted. The differences between the modified vehicle heat transfer medium heating device 1 and the above embodiment will be described below.

[0051] Referring to Figures 9 and 10, the modified vehicle heat transfer medium heating device 1 includes a pair of spare conductive pads 7a and 7b in addition to the pair of conductive pads 6a and 6b. The pair of spare conductive pads 7a and 7b are provided on the control board 4, spaced apart from each other, and are separate from the heater control circuit 30 and the pair of conductive pads 6a and 6b, and are conductive. One of the pair of spare conductive pads 7a and 7b is electrically connected to the intermediate line 4a1 of the first power line 4a, and the other of the pair of spare conductive pads 7a and 7b is electrically connected to the second power line 4b. When the housing 2 is fixed to the vehicle in a predetermined pre-position different from the predetermined reference position, the pair of spare conductive pads 7a and 7b are located below the circuit elements constituting the heater control circuit 30.

[0052] Specifically, the pair of spare conductive pads 7a and 7b are conductive patterns formed on the control board 4 by etching or the like, similar to the pair of conductive pads 6a and 6b, but they do not constitute the original electrical circuit of the heater control circuit 30. The pair of spare conductive pads 7a and 7b are also exposed on the control board 4 and are separated from each other by a predetermined insulating distance. Although not particularly limited, two of the four sides of the rectangular control board 4 extend in a direction perpendicular to the sides corresponding to the pair of conductive pads 6a and 6b, and the edge corresponding to one of these two sides constitutes the lower edge of the control board 4 in the predetermined pre-position. The pair of spare conductive pads 7a and 7b are provided near the edge that constitutes the lower edge of the control board 4 in the predetermined pre-position, and are separated from each other in a direction along that edge (horizontal in the pre-position state).

[0053] Even if the housing 2 assumes a different posture from the predetermined reference posture initially planned, this different posture can often be anticipated in advance. Therefore, the predetermined backup posture can be anticipated beforehand. When the housing 2 is fixed to the vehicle in the predetermined backup posture, the vehicle heat transfer medium heating device 1 can reliably stop the power supply to the heater 3 without malfunctioning, even if water enters the housing 2, thanks to the pair of backup conductive pads 7a and 7b.

[0054] In addition, there may be cases where multiple postures different from the predetermined standard posture can be anticipated in advance. In this case, as shown in Figure 11, the vehicle heat transfer medium heating device 1 only needs to be equipped with a number of spare conductive pads 7a and 7b corresponding to the number of anticipated postures (3 patterns in Figure 11). Specifically, the pair of spare conductive pads 7a and 7b are provided near the edges of three sides of the four sides, excluding the sides corresponding to the pair of conductive pads 6a and 6b. In other words, when multiple (3 in Figure 11) predetermined spare postures are defined, the pair of spare conductive pads 7a and 7b are provided near the edge of the control board 4 for each spare posture. This improves the degree of freedom in the fixing posture of the housing 2 to the vehicle.

[0055] Furthermore, the pair of conductive pads 6a, 6b and the pair of spare conductive pads 7a, 7b are provided near the longitudinal center of the edge of the control board 4, but are not limited to this, and may be provided at the corners of the control board 4 included in the edge of the control board 4. The first power line 4a on which the circuit breaker 4e is provided is connected to the positive terminal (output side) of the external power supply B, but is not limited to this. The first power line 4a on which the circuit breaker 4e is provided may be connected to the negative terminal (ground side) of the external power supply B. In other words, the circuit breaker 4e may be provided not only on the positive terminal side power line, but also on the negative terminal side power line.

[0056] Although embodiments and some modifications of the present invention have been described above, the present invention is not limited to the embodiments and modifications described above, and further modifications and changes are possible based on the technical idea of ​​the present invention. [Explanation of Symbols]

[0057] 1...Vehicle heat transfer medium heating device, 2...Housing, 3...Heater, 4...Control board, 4a...First power line, 4a1...Intermediate line, 4b...Second power line, 4e...Circuit breaker, 6a, 6b...Pair of conductive pads, 7a, 7b...Pair of spare conductive pads, 30...Heater control circuit, 31...First IGBT (circuit element), 32...Second IGBT (circuit element), 33...IGBT driver (circuit element), 34...Microcontroller (circuit element), 35a...Positive side power line connection (circuit element), 35b...Negative side power line connection (circuit element), 35c...Positive side heater line connection (circuit element), 35d...Negative side heater line connection (circuit element), 35e...Positive side wiring pattern (circuit element), 35f...Negative side wiring pattern (circuit element), B...External power supply

Claims

1. A vehicle heat transfer medium heating device comprising a housing, a heater that generates heat by being powered from an external power source to heat a heat transfer medium inside the housing, and a control board on which a heater control circuit for controlling the power supply to the heater is mounted and housed inside the housing, The control board includes a pair of conductive pads that are provided on the control board separately from the heater control circuit and spaced apart from each other, and are conductive, and a pair of spare conductive pads that are provided on the control board separately from the heater control circuit and the pair of conductive pads and are conductive, A circuit breaker is provided in the first power line that electrically connects one pole of the external power supply to the heater control circuit, which cuts off the power supply when a current exceeding a predetermined value flows through it. One of the pair of conductive pads is electrically connected to the intermediate line between the circuit breaker and the heater control circuit in the first power line. The other of the pair of conductive pads is electrically connected to a second power line that electrically connects the other pole of the external power supply to the heater control circuit. When the housing is fixed to the vehicle in a predetermined reference position, the pair of conductive pads are located below the circuit elements constituting the heater control circuit. One of the pair of spare conductive pads is electrically connected to the intermediate line of the first power line, The other of the pair of spare conductive pads is electrically connected to the second power line. A vehicle heat transfer medium heating device, wherein, when the housing is fixed to the vehicle in a predetermined pre-position different from the predetermined reference position, the pair of pre-conductive pads are located below the circuit elements.

2. The vehicle heat transfer medium heating device according to claim 1, wherein the pair of conductive pads are provided near the edge of the control board.

3. Multiple predetermined pre-positions are defined, The vehicle heat transfer medium heating device according to claim 1 or 2, wherein the pair of spare conductive pads are provided near the edge of the control board for each spare position.

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