Heat-medium-heating device

Abstract

[Problem] To provide a heat-medium-heating device with which a plurality of power switching elements for controlling energization of electric heaters can be maintained in an appropriate temperature zone. [Solution] A heat-medium-heating device 1 comprises heat medium flow passages 9, 11 provided within a housing 2, electric heaters 18, 19 for heating a heat medium flowing through the heat medium flow passages, and a plurality of power switching elements 22-24 for controlling energization of the electric heaters. Each power switching element is disposed in a heat exchange relationship with the heat medium flowing through the heat medium flow paths. Among the power switching elements, the power switching element 24 having the greatest heat generation amount by energization is arranged farther upstream with respect to the flow of the heat medium than the other power switching elements 22, 23.

Description

Heat medium heating device

[0001] The present invention relates to a heat medium heating device that uses an electric heater to heat a heat medium flowing through a heat medium flow path formed in a housing.

[0002] A conventional heat medium heating device used for air conditioning the interior of a vehicle has a heat medium flow path formed in a housing, and a cylindrical electric heater called a cartridge heater is arranged in this heat medium flow path to heat the heat medium flowing through the heat medium flow path. In this case, for example, two heat medium flow paths are provided in the housing, and one end of each heat medium flow path is connected by a communication path, and an electric heater is arranged in each heat medium flow path, and the heat medium flowing in through a heat medium inlet port formed at the other end of one heat medium flow path is heated by each electric heater and then flows out from a heat medium outlet port formed at the other end of the other heat medium flow path (see, for example, Patent Document 1).

[0003] Special table 2016-536197 publication

[0004] Here, the current supply to each electric heater is controlled using a power switching element such as an IGBT, but it is also possible to provide an additional power switching element that adjusts the overall power of the two electric heaters. In this case, the currents flowing through each power switching element will join together and flow through the power switching element that adjusts the overall power, which may result in the greatest heat generation and the risk of failure.

[0005] The present invention has been made to solve the above-mentioned conventional technical problems, and aims to provide a heat medium heating device that can maintain a plurality of power switching elements that control the current supply to an electric heater in an appropriate temperature range.

[0006] In order to solve the above problems, the heat medium heating device of the present invention comprises a heat medium flow path provided in a housing, an electric heater that heats the heat medium flowing through this heat medium flow path, and a plurality of power switching elements that control the supply of current to the electric heater, wherein each power switching element is arranged in a heat exchange relationship with the heat medium flowing through the heat medium flow path, and among the power switching elements, the power switching element that generates the greatest amount of heat when energized is arranged upstream of the other power switching elements with respect to the flow of the heat medium.

[0007] The heat transfer medium heating device of the invention of claim 2 is characterized in that in the above invention, a plurality of heat transfer medium flow paths are provided within the housing, an electric heater is disposed in each heat transfer medium flow path, and a power switching element is provided to control the supply of electricity to each electric heater.

[0008] The heat medium heating device of the invention of claim 3 is characterized in that it comprises a specific power switching element through which currents flowing through the power switching elements of the above invention join together, and this specific power switching element is arranged upstream of the other power switching elements in the flow of the heat medium.

[0009] The heat medium heating device of the invention of claim 4 is characterized in that it is provided in the above invention and includes a control board provided within a housing and on which a control device for controlling the electric heaters is mounted, and the control device controls the supply of electricity to the electric heaters using power switching elements for controlling the supply of electricity to each electric heater, and adjusts the overall power of each electric heater using a specific power switching element.

[0010] According to the present invention, in a heat medium heating device including a heat medium flow path provided in a housing, an electric heater for heating the heat medium flowing through the heat medium flow path, and a plurality of power switching elements for controlling the supply of electricity to the electric heater, each power switching element is arranged in a heat exchange relationship with the heat medium flowing through the heat medium flow path, so that each power switching element is cooled by the heat medium and the heat medium is heated.

[0011] In this case, among the power switching elements, the power switching element that generates the greatest amount of heat when energized is positioned upstream of the flow of the heat medium relative to the other power switching elements. Therefore, the power switching element that generates the greatest amount of heat exchanges heat with the heat medium with the lowest temperature that has flowed into the heat medium flow path, and is efficiently cooled, while the heat medium is effectively heated.

[0012] This makes it possible to efficiently heat the heat medium and maintain all power switching elements in an appropriate temperature range, thereby preventing breakdowns in the power switching elements.

[0013] For example, in the case of the invention of claim 2, where a plurality of heat medium flow paths are provided within the housing and an electric heater is disposed in each heat medium flow path, and where power switching elements are provided to control the current supply to each electric heater, and a specific power switching element through which the currents flowing through each power switching element join together as in the invention of claim 3, this specific power switching element is disposed upstream of the other power switching elements in terms of the flow of the heat medium.

[0014] As in the invention of claim 4, the control device controls the power supply to the electric heaters, for example, by using power switching elements for controlling the power supply to each electric heater, and the overall power of each electric heater is adjusted by a specific power switching element.

[0015] It is a perspective view showing the appearance of a heat medium heating device according to an embodiment of the present invention. It is a schematic cross-sectional plan view for explaining a flow path of a heat medium in the heat medium heating device of Fig. 1. It is a plan view showing the interior of the heat medium heating device of Fig. 1. It is a longitudinal cross-sectional side view of the heat medium heating device corresponding to Fig. 3. It is an electric circuit diagram of a control device of the heat medium heating device of Fig. 1.

[0016]

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a perspective view showing the appearance of a heat medium heating device 1 according to an embodiment of the present invention, Fig. 2 is a schematic cross-sectional plan view illustrating the flow of heat medium within the heat medium heating device 1, Fig. 3 is a plan view showing the inside of the main body 3 of the housing 2 of the heat medium heating device 1 in Fig. 1 with the cover 4 removed, and Fig. 4 is a vertical cross-sectional side view of Fig. 3.

[0017] The heat medium heating device 1 of the embodiment is used to air-condition the interior of a vehicle (not shown), and has a housing 2 composed of a main body 3 and a cover 4 attached to the main body 3. In the embodiment, two flow path sections 6 and 7 (made of metal) are arranged side by side within the main body 3 of the housing 2, spaced apart from each other by a gap 8, and heat medium flow paths 9 and 11 are formed within the flow path sections 6 and 7, respectively. That is, the heat medium flow paths 9 and 11 are arranged spaced apart from each other by the gap 8.

[0018] A communication part 13 having a communication flow path 12 formed therein is connected to one end of the flow path parts 6, 7, and one end of both heat medium flow paths 9, 11 are connected by this communication flow path 12. A heat medium inlet part 16 is connected to the other end of one heat medium flow path 9, and a heat medium outlet part 17 is connected to the other end of the other heat medium flow path 11.

[0019] In each figure, reference numerals 18 and 19 denote rod-shaped electric heaters (heat generating elements) constituted by cartridge heaters (cylindrical heaters) in this embodiment, and electric heater (electric heater 1) 18 is inserted into one heat medium flow path 9 with a gap between it and the inner surface of flow path portion 6, while electric heater (electric heater 2) 19 is inserted into the other heat medium flow path 11 with a gap between it and the inner surface of flow path portion 7.

[0020] A control board 21 is provided at a position on the cover 4 side of each of the flow passage sections 6, 7 inside the main body 3. On this control board 21, a power switching element 22 (IGBT1) for controlling the supply of electricity to the electric heater 18, a power switching element 23 (IGBT2) for controlling the supply of electricity to the electric heater 19, and a power switching element 24 (IGBT3) for adjusting the overall power of each of the electric heaters 18, 19 are mounted.

[0021] In this embodiment, the plurality of power switching elements 22 to 24 are configured by IGBTs. Also mounted on the control board 21 are a capacitor 26 and a choke coil 27 that configure a noise filter 25. The capacitor 26 and the choke coil 27 are circuit components that are larger in size than the power switching elements 22 to 24. The power switching elements 22 to 24, the capacitor 26, the choke coil 27, etc. configure a control device 31 (FIG. 5) for the heat medium heating device 1.

[0022] Furthermore, each of the power switching elements 22 to 24 is mounted on the surface of the control board 21 facing the flow path sections 9 and 11, and is attached in a heat exchange relationship with the flow path section 6. As a result, each of the power switching elements 22 to 24 is arranged in a heat exchange relationship with the heat medium flowing in the heat medium flow path 9. Furthermore, the power switching element 24 (a specific power switching element) is arranged upstream of the other power switching elements 22 and 23 with respect to the flow of the refrigerant (FIG. 3).

[0023] Furthermore, a capacitor 26 and a choke coil 27 are also mounted on the surface of the control board 21 on the side of each of the flow path sections 9 and 11, and are inserted and arranged in the gap 8 between the flow path section 6 (heat medium flow path 9) and the flow path section 7 (heat medium flow path 11) (FIGS. 3 and 4).

[0024] Next, Figure 5 shows the electrical circuit of the control device 31. The noise filter 25 mentioned above is connected to the vehicle battery (DC power source) (not shown). The power switching element 22 and the electric heater 18 are connected in series, and the power switching element 23 and the electric heater 19 are connected in series, with these two series circuits being connected in parallel. The power switching element 24 is connected in series to these parallel circuits, and a current sensor 32 is connected in series to the power switching element 24.

[0025] The power switching elements 22 and 23 are connected to the positive electrode side of the noise filter 25, and the current sensor 32 is connected to the negative electrode side. As a result, the currents that flow through the two power switching elements 22 and 23 join together and flow through the power switching element 24.

[0026] 5, reference numeral 36 denotes a control unit configured by a microcomputer, and drivers 37, 38, and 39 are connected to the output of this control unit 36. Driver 37 is connected to the gate of power switching element 22, and driver 38 is connected to the gate of power switching element 23. Driver 39 is connected to the gate of power switching element 24.

[0027] The control unit 36 ​​receives the output of the current sensor 32, as well as the outputs of the inlet temperature sensor 41 and the outlet temperature sensor 42. The inlet temperature sensor 41 detects the temperature of the heat medium flowing into the heat medium flow path 9 from the heat medium inlet portion 16, and the outlet temperature sensor 42 detects the temperature of the heat medium flowing out from the heat medium outlet portion 17. In this application, the heat medium flowing in from the heat medium inlet portion 16 means the heat medium immediately before or immediately after entering the heat medium inlet portion 16, and the heat medium flowing out from the heat medium outlet portion 17 means the heat medium immediately before or immediately after exiting the heat medium outlet portion 17.

[0028] Next, we will explain the operation of the heat medium heating device 1 configured as described above. A heat medium circuit (not shown) is connected to the heat medium inlet portion 16, and a heat medium (water in this embodiment) is caused to flow from the heat medium inlet portion 16 into the heat medium flow path 9 by a pump (not shown). The heat medium that has flowed into the heat medium flow path 9 flows into the heat medium flow path 11 via the communication flow path 12, and then flows out of the heat medium outlet portion 17 into the heat medium circuit described above.

[0029] Meanwhile, the control unit 36 ​​of the control device 31 controls the switching of the power switching elements 22 to 24 by the drivers 37 to 39 based on the outputs of the inlet temperature sensor 41, the outlet temperature sensor 42, and the current sensor 32. As a result, the electric heaters 18, 19 are energized and generate heat, so that the heat medium that has flowed into the heat medium flow path 9 is heated as it passes around the electric heater 18, and is further heated as it enters the heat medium flow path 11 and passes around the electric heater 19.

[0030] A heater core disposed in the HV unit of the vehicle is connected to the heat medium circuit, and the heat medium heated by the heat medium heating device 1 is circulated through this heater core. Air supplied to the vehicle cabin is passed through the heater core, thereby heating the cabin.

[0031] The control unit 36 ​​controls the switching of the power switching elements 22, 23 based on the temperature of the inflowing heat medium detected by the inlet temperature sensor 41 and the temperature of the outflowing heat medium detected by the outlet temperature sensor 42, and controls the supply of electricity to each of the electric heaters 18, 19. The currents flowing through these power switching elements 22, 23 (electric heaters 18, 19) join together and flow to a power switching element (specific power switching element) 24. The control unit 36 ​​controls the switching of the power switching element 24 based on the value of this joined current detected by the current sensor 32, and adjusts the overall power of each of the electric heaters 18, 19.

[0032] Here, the currents flowing through the power switching elements 22, 23 are joined together and flow through the power switching element 24 (specific power switching element), so the power switching element 24 generates more heat than the power switching elements 22, 23 and generates the greatest amount of heat. However, because the power switching element 24 is arranged upstream of the other power switching elements 22, 23 with respect to the flow of the heat medium, it exchanges heat with the heat medium that has the lowest temperature and has flowed into the heat medium flow path 9.

[0033] As a result, the heat from the power switching element 24, which generates the most heat, is smoothly transferred to the heat medium, so that the power switching element 24 is effectively cooled and the temperature of the heat medium is efficiently increased by the heat from the power switching element 24. Note that the heat generated by the power switching elements 22 and 23 is also transferred to the heat medium downstream of the power switching element 24, so that the power switching elements 22 and 23 are also cooled and the temperature of the heat medium further increases.

[0034] As a result, the heat medium can be efficiently heated, and all of the power switching elements 22 to 24 can be maintained in an appropriate temperature range, thereby preventing failure of the power switching elements 22 to 24.

[0035] As described above, in the heat medium heating device 1, the heat medium flow paths 9, 11 are arranged at a distance from each other, so that heat exchange between the heat medium flow paths 9, 11 does not occur. Therefore, even when the temperature of the heat medium flowing in from the heat medium inlet portion 16 is detected by the inlet temperature sensor 41 as in the embodiment and the electric heaters 18, 19 are controlled based on the temperature, it is possible to avoid the inconvenience of detecting an erroneous temperature.

[0036] Furthermore, even when the electric heaters 18, 19 are disposed in the heat medium flow paths 9, 11, respectively, to heat the heat medium flowing in from the heat medium inlet portion 16 and cause the heat medium to flow out from the heat medium outlet portion 17, as in the embodiment, it is possible to avoid the inconvenience of the outflowing refrigerant being cooled by the inflowing refrigerant.

[0037] In particular, a control board 21 on which circuit components constituting a control device 31 for controlling the electric heaters 18, 19 are mounted is provided inside the housing 2, and the capacitor 26 and choke coil 27, which are circuit components constituting a noise filter 25 of this control board 21, are arranged within the gap 8 between each heat medium flow path 9, 11. Therefore, the dead space (gap 8) between each heat medium flow path 9, 11 can be effectively used for arranging the circuit components, and the heat medium heating device 1 can be made smaller.

[0038] In particular, in the embodiment, the capacitor 26 and the choke coil 27, which are circuit components larger in size than the power switching elements 22 to 24, are arranged within the space 8, which effectively reduces the size of the entire device. Furthermore, even if it becomes necessary to change the capacitor 26 or the choke coil 27 to meet the required specifications, the heat medium heating device 1 can be accommodated within the space 8 without increasing its size, which increases the degree of freedom in design.

[0039] On the other hand, since the power switching elements 22 to 24 are arranged in a heat exchange relationship with the heat medium, the heat generated by the power switching elements 22 to 24 heats the heat medium, and the power switching elements 22 to 24 themselves can be cooled.

[0040] In the embodiment, the capacitor 26 and the choke coil 27 are disposed within the gap 8, but only one of them is effective. Also, in the embodiment, the inlet temperature sensor 41 and the outlet temperature sensor 42 are provided to control the energization of the electric heaters 18, 19, but control may be performed using only the inlet temperature sensor 41 or only the outlet temperature sensor 42.

[0041] Furthermore, although the embodiment has been described as having two heat medium flow paths 9 and 11, the present invention is also effective when more heat medium flow paths are configured and arranged at a distance from each other. Furthermore, although the power switching elements 22 to 24 are configured as IGBTs in the embodiment, they may be configured as MOSFETs or the like. Furthermore, although the embodiment has been described as being a heat medium heating device used in vehicle air conditioning, the heat medium heating device 1 is not limited to this, and it goes without saying that it is effective in any heating system that uses a heat medium.

[0042] REFERENCE SIGNS LIST 1 Heat medium heating device 2 Housing 8 Spacing 9, 11 Heat medium flow path 12 Communication flow path 16 Heat medium inlet portion 17 Heat medium outlet portion 18, 19 Electric heater 21 Control board 22 to 24 Power switching element 25 Noise filter 26 Capacitor 27 Choke coil 31 Control device 32 Current sensor 36 Control unit 41 Inlet temperature sensor 42 Outlet temperature sensor

Claims

1. A heat medium heating device comprising a heat medium flow path provided within a housing, an electric heater for heating the heat medium flowing through the heat medium flow path, and a plurality of power switching elements for controlling the supply of current to the electric heater, wherein each of the power switching elements is disposed in a heat exchange relationship with the heat medium flowing through the heat medium flow path, and among the power switching elements, a power switching element which generates the greatest amount of heat when current is applied is disposed upstream of the other power switching elements with respect to the flow of the heat medium.

2. The heat medium heating device according to claim 1, characterized in that a plurality of heat medium flow paths are provided within the housing, an electric heater is disposed in each heat medium flow path, and a power switching element is provided for controlling the supply of electricity to each electric heater.

3. The heat medium heating device according to claim 2, further comprising a specific power switching element through which currents flowing through the respective power switching elements are joined together, and the specific power switching element is disposed upstream of the flow of the heat medium relative to the other power switching elements.

4. The heat medium heating device according to claim 3, further comprising a control board mounted with a control device for controlling the electric heaters, the control device controlling the power supply to the electric heaters by power switching elements for controlling the power supply to each of the electric heaters, and adjusting the overall power of each of the electric heaters by the specific power switching element.

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