JP7779809B2 - complex device - Google Patents

Description

The present invention relates to a combined device having a refrigerant compression function and a heat medium heating function.

Patent Document 1 describes a vehicle air conditioning system that can be used in vehicles such as hybrid and electric vehicles. The vehicle air conditioning system described in Patent Document 1 has a refrigerant circuit that includes an electric compressor that compresses a refrigerant, a radiator that dissipates heat from the refrigerant discharged from the electric compressor to heat the air supplied to the vehicle cabin, an expansion valve that reduces the pressure and expands the heat-dissipated refrigerant, and a heat exchanger equivalent to an evaporator that exchanges heat between the reduced-pressure, expanded refrigerant and outside air. The vehicle air conditioning system described in Patent Document 1 also has an electric heat medium heater that heats the heat medium to assist the radiator in heating the vehicle cabin, and a heat medium-air heat exchanger that heats the air supplied to the vehicle cabin with the heated heat medium.

Japanese Patent Application Laid-Open No. 2014-213765

The vehicle air conditioning system described in Patent Document 1 is capable of compensating for the lack of heating capacity provided by the radiator. However, the vehicle air conditioning system described in Patent Document 1 has an electric compressor, a heat medium heater, and other components installed separately. This makes the entire system larger, leaving room for improvement in terms of installation space, etc.

The present invention aims to provide a combined device that can contribute to the miniaturization of vehicle air conditioning systems and the like, and to prevent damage caused by surge voltages to switching elements used in combined devices for power supply, etc., while suppressing increases in switching loss.

One aspect of the present invention provides a combined device having refrigerant compression and heat medium heating functions. The combined device includes a compressor housing that houses a compression mechanism that compresses the refrigerant and an electric motor that drives the compression mechanism, and has a refrigerant inlet through which the refrigerant flows into the compressor housing and a refrigerant outlet through which the refrigerant compressed by the compression mechanism flows out to the outside; a heater housing that houses an electric heater that heats a heat medium, and has a heat medium inlet through which the heat medium flows into the compressor housing and a heat medium outlet through which the heat medium heated by the electric heater flows out to the outside; and a circuit housing that houses a circuit board mounted with electronic circuits including a motor drive circuit that drives the electric motor and a heater control circuit that controls the electric heater. The compressor housing, heater housing, and circuit housing are integrally joined. Furthermore, the motor drive circuit and heater control circuit each include a switching element. The switching frequency of the switching elements of the heater control circuit is set lower than the switching frequency of the switching elements of the motor drive circuit, the switching speed of the switching elements of the heater control circuit is set slower than the switching speed of the switching elements of the motor drive circuit, and the electronic circuit is configured so that the parasitic inductance of the wiring connected to the switching elements of the motor drive circuit is smaller than the parasitic inductance of the wiring connected to the switching elements of the heater control circuit.

The present invention provides a combined device that can contribute to the miniaturization of vehicle air conditioning systems and the like. Furthermore, the present invention can prevent damage caused by surge voltages to switching elements used in combined devices for power supply, etc., while suppressing increases in switching loss.

FIG. 1 is a front view of a multifunction device according to an embodiment. FIG. 2 is a right side view of the multifunction peripheral according to the embodiment. FIG. 2 is a top view of the multifunction device according to the embodiment. 3 is a partial schematic cross-sectional view of the composite device according to the embodiment, which corresponds to the cross-sectional view taken along line AA in FIG. 2. FIG. 2 is a diagram illustrating an example of the configuration of a main part of an electronic circuit including a motor drive circuit and a heater control circuit of a multifunction peripheral according to an embodiment. FIG. 4 is a partial schematic cross-sectional view of the composite device according to the embodiment, which corresponds to the cross-sectional view taken along line BB in FIG. 3. FIG. 2 is a block diagram showing a schematic configuration of a control system of the multifunction peripheral according to the embodiment. 3A and 3B are diagrams showing examples of wiring patterns of a circuit board on which the electronic circuit is mounted.

The following describes an embodiment of the present invention with reference to the accompanying drawings.

Figures 1 to 4 show the general configuration of a multifunction device 1 according to an embodiment of the present invention. Figure 1 is a front view of the multifunction device 1 according to an embodiment, Figure 2 is a right side view of the multifunction device 1 according to an embodiment, Figure 3 is a top view of the multifunction device 1 according to an embodiment, and Figure 4 is a partial schematic cross-sectional view of the multifunction device according to an embodiment, which corresponds to the A-A cross-sectional view of Figure 2.

The combined device 1 according to this embodiment has a refrigerant compression function that compresses a refrigerant and a heat medium heating function that heats a heat medium separate from the refrigerant. In other words, the combined device 1 has a configuration in which a refrigerant compressor and a heat medium heating device are integrated.

The combined device 1 can be applied to the vehicle air conditioning system described above. That is, the combined device 1 can be incorporated into a refrigerant circuit through which a refrigerant circulates and a heat medium circuit through which a heat medium circulates using a pump unit such as an electric pump. For example, the refrigerant compression function unit of the combined device 1 can be incorporated into the refrigerant circuit and configured to compress the refrigerant that has passed through an expansion valve and an evaporator (or an equivalent heat exchanger) and supply the compressed refrigerant to a radiator (refrigerant-air heat exchanger) that heats the air supplied to the vehicle cabin. The heat medium heating function unit of the combined device 1 can be incorporated into the heat medium circuit and configured to heat the heat medium that has passed through a heat medium-air heat exchanger that heats the air supplied to the vehicle cabin and supply the heated heat medium to the heat medium-air heat exchanger. The refrigerant and heat medium can each be selected arbitrarily. For example, a gaseous refrigerant can be used as the refrigerant, and a liquid can be used as the heat medium. Although not particularly limited, water (including water mixed with antifreeze, etc.) is typically used as the heat medium. Therefore, the heat medium heating function (heat medium heating device) can also be referred to as a water heating function (water heating device).

Referring to Figures 1 to 4, the composite device 1 has a housing 2. The housing 2 of the composite device 1 includes a first housing 2A, a second housing 2B, a third housing 2C, a first cover 2D, a second cover 2E, and a third cover 2F, which are integrally joined (fastened) together by fastening members such as bolts (not shown).

The first housing 2A is formed in a generally cylindrical shape. A compression mechanism 3 that compresses the refrigerant and an electric motor 4 that drives the compression mechanism 3 are housed within the first housing 2A in series in the axial direction. Although not limited to this, the compression mechanism 3 may be a scroll compression mechanism including a fixed scroll and a movable (orbiting) scroll. The output shaft 4a of the electric motor 4 is connected to the compression mechanism 3 (e.g., the movable (orbiting) scroll).

One of the two open ends of the first housing 2A (the lower open end in Figures 1 and 2), i.e., the open end of the first housing 2A on the compression mechanism 3 side, is closed by a first cover 2D. The first housing 2A, which houses the compression mechanism 3 that compresses the refrigerant and the electric motor 4 that drives it, may also be referred to as the "compressor housing."

The second housing 2B is located to the side of the first housing 2A. The second housing 2B is formed in a generally rectangular cylindrical shape. An electric heater 5 that heats the heat medium is housed inside the second housing 2B.

One of the two open ends of the second housing 2B (the lower open end in Figures 1 and 2) is closed by a second cover 2E. The second housing 2B, which houses the electric heater 5 that heats the heat medium, may also be referred to as the "heater housing."

The third housing 2C is box-shaped and open at the top. The third housing 2C houses a motor drive circuit 20 that drives (controls) the electric motor 4 and a heater control circuit 30 that controls the electric heater 5. Specifically, in this embodiment, the third housing 2C houses a circuit board 6 on which electronic circuits including the motor drive circuit 20 and the heater control circuit 30 are mounted.

The bottom wall 7 of the third housing 2C closes the other open end of the first housing 2A (the upper open end in Figures 1 and 2), i.e., the open end of the first housing 2A facing the electric motor 4, and the other open end of the second housing 2B (the upper open end in Figures 1 and 2). This separates the interior of the first housing 2A from the interior of the third housing 2C, and separates the interior of the second housing 2B from the interior of the third housing 2C. In other words, the bottom wall 7 of the third housing 2C has a first partition 71 that separates the interior of the first housing 2A from the interior of the third housing 2C, and a second partition 72 that separates the interior of the second housing 2B from the interior of the third housing 2C.

The top surface (open end) of the third housing 2C is closed by the third cover 2F. The third housing 2C, which houses the motor drive circuit 20 and heater control circuit 30 (specifically, the circuit board 6 on which the electronic circuits including these are mounted), may also be referred to as the "circuit housing" or "board housing."

In the combined device 1, the refrigerant compression function (electric compressor) is realized mainly by the compression mechanism 3, electric motor 4, and motor drive circuit 20, and the heat medium heating function (heat medium heating device) is realized mainly by the electric heater 5 and heater control circuit 30.

The first housing 2A is formed with a refrigerant inlet 8 for allowing the refrigerant circulating through the refrigerant circuit to flow into the interior. The refrigerant to be introduced is, for example, a refrigerant that has passed through an expansion valve and an evaporator (or an equivalent heat exchanger), i.e., a low-temperature, low-pressure refrigerant. In this embodiment, the refrigerant inlet 8 is provided in the portion of the first housing 2A facing the third housing 2C, i.e., near the first partition 71 that separates the interior of the first housing 2A from the interior of the third housing 2C. Preferably, the refrigerant inlet 8 is configured to allow the refrigerant circulating through the refrigerant circuit to flow into the first housing 2A so that at least a portion of the refrigerant flows along the first partition 71.

The (low-temperature, low-pressure) refrigerant that flows into the first housing 2A through the refrigerant inlet 8 flows through the first housing 2A and is drawn into the compression mechanism 3. The refrigerant drawn into the compression mechanism 3 is compressed by the compression mechanism 3 and discharged as high-temperature, high-pressure refrigerant. The discharged (high-temperature, high-pressure) refrigerant flows out through the refrigerant outlet 9 formed in the first housing 2A and is supplied, for example, to the radiator (refrigerant-air heat exchanger) mentioned above.

In this embodiment, the refrigerant outlet 9 is located on the first cover 2D side of the first housing 2A, i.e., at a position spaced apart from the refrigerant inlet 8 in the vertical direction in Figures 1 and 2. Therefore, in this embodiment, the refrigerant that flows into the first housing 2A from the refrigerant inlet 8 flows from the top to the bottom within the first housing 2A in Figures 1 and 2.

The first partition 71 can be cooled by the (low-temperature, low-pressure) refrigerant flowing into the first housing 2A through the refrigerant inlet 8. The electric motor 4 can also be cooled by the refrigerant flowing inside the first housing 2A. The refrigerant inlet 8, the interior of the first housing 2A, and the refrigerant outlet 9 constitute part of the refrigerant circuit.

The second housing 2B is formed with a heat medium inlet 10 for allowing the heat medium circulating through the heat medium circuit to flow into the interior. The heat medium to be introduced is, for example, a heat medium that has passed through the heat medium-air heat exchanger described above, i.e., a low-temperature heat medium. In this embodiment, the heat medium inlet 10 is provided in the portion of the second housing 2B facing the third housing 2C, i.e., near the second partition 72 that separates the interior of the second housing 2B from the interior of the third housing 2C, and on the far side in FIG. 1 (right side in FIG. 2). Preferably, the heat medium inlet 10 is configured to allow the heat medium circulating through the heat medium circuit to flow into the second housing 2B so that at least a portion of the heat medium flows along the second partition 72.

The (low-temperature) heat medium that flows into the second housing 2B through the heat medium inlet 10 flows inside the second housing 2B, where it is heated by the electric heater 5 and increases in temperature. The heated heat medium flows out through the heat medium outlet 11 formed in the second housing 2B and is supplied, for example, to the heat medium-air heat exchanger described above.

In this embodiment, the heat medium outlet 11 is located near the second partition 72 that separates the interior of the second housing 2B from the interior of the third housing 2C, and on the near side in FIG. 1 (left side in FIG. 2). Therefore, in this embodiment, the heat medium that flows into the second housing 2B from the heat medium inlet 10 flows within the second housing 2B along the second partition 72 from right to left in FIGS. 2 and 4. In other words, in the combined device 1, the flow direction of the heat medium is approximately perpendicular to the flow direction of the refrigerant.

The second partition 72 can be cooled by a (low-temperature) heat medium flowing into the second housing 2B through the heat medium inlet 10. The heat medium inlet 10, the interior of the second housing 2B, and the heat medium outlet 11 form part of the heat medium circuit.

Although not shown in the figure, the power supply line from the motor drive circuit 20 to the electric motor 4 and the power supply line from the heater control circuit 30 to the electric heater 5 each extend through the bottom wall 7 of the third housing 2C in an airtight and liquid-tight manner.

Next, we will explain the motor drive circuit 20 that drives the electric motor 4 and the heater control circuit 30 that controls the electric heater 5. Figure 5 is a diagram showing an example of the main configuration of the electronic circuit including the motor drive circuit 20 and the heater control circuit 30.

In this embodiment, the motor drive circuit 20 is configured to drive (control) the electric motor 4 by converting DC voltage from a high-voltage power supply HV, such as a high-voltage battery mounted on the vehicle, into three-phase AC voltage and supplying it to the electric motor 4. The heater control circuit 30 is also configured to control the temperature of the electric heater 5 by controlling the application of power from the high-voltage power supply HV to the electric heater 5 (the flow of electricity between the high-voltage power supply HV and the electric heater 5). Furthermore, in this embodiment, the electronic circuit includes a smoothing capacitor SC that smoothes the DC voltage from the high-voltage power supply HV.

As shown in FIG. 5, in the electronic circuit, smoothing capacitor SC is connected between the power line (HV+) and ground line (HVGND) of the high-voltage power supply HV. Smoothing capacitor SC smoothes the DC voltage supplied from the high-voltage power supply HV to the motor drive circuit 20 and heater control circuit 30.

The motor drive circuit 20 includes a first power module 21 and a first driver 22. Note that the motor drive circuit 20 may also refer to the state including the smoothing capacitor SC.

The first power module 21 includes six power switching elements (hereinafter simply referred to as "first switching elements") Q1-Q6 and six diodes D1-D6. Although not limited to these, the first switching elements Q1-Q6 may be IGBTs (insulated gate bipolar transistors). By PWM-controlling the first switching elements Q1-Q6, the first power module 21 converts the DC voltage from the high-voltage power supply HV into three-phase AC voltage and supplies it to the electric motor 4.

Specifically, the first power module 21 has a U-phase arm, a V-phase arm, and a W-phase arm arranged in parallel with each other between the power line of the high-voltage power supply HV and the ground line.

The U-phase arm has two first switching elements Q1 and Q2 connected in series, and diodes D1 and D2 connected in anti-parallel to each of the first switching elements Q1 and Q2, respectively.

Two first switching elements Q3 and Q4 are connected in series in the V-phase arm, and diodes D3 and D4 are connected in anti-parallel to each of the first switching elements Q3 and Q4, respectively.

Two first switching elements Q5 and Q6 are connected in series in the W-phase arm, and diodes D5 and D6 are connected in anti-parallel to each of the first switching elements Q5 and Q6, respectively.

Furthermore, the midpoints of the U-, V-, and W-phase arms are connected at one end to the other end of the U-, V-, and W-phase coils of the electric motor 4, which are star-connected. In other words, the midpoints of the first switching elements Q1 and Q2 of the U-phase arm are connected to the U-phase coil, the midpoints of the first switching elements Q3 and Q4 of the V-phase arm are connected to the V-phase coil, and the midpoints of the first switching elements Q5 and Q6 of the W-phase arm are connected to the W-phase coil.

Therefore, by controlling (PWM-controlled) the ratio between the ON periods of the first switching elements Q1, Q3, and Q5 on the power line side of each phase arm and the ON periods of the first switching elements Q2, Q4, and Q6 on the ground line side, the first power module 21 converts the DC voltage from the high-voltage power supply HV, smoothed by the smoothing capacitor SC, into a three-phase AC voltage and supplies it to the electric motor 4, thereby driving the electric motor 4 and the compression mechanism 3.

The first driver 22 drives (switches) the gates of the first switching elements Q1 to Q6 on and off based on a control signal (PWM signal) from the control unit 15 (described later).

In other words, in this embodiment, the operation of the motor drive circuit 20 (the switching operation of the first switching elements Q1 to Q6), and ultimately the operation of the electric motor 4 and compression mechanism 3 (i.e., the refrigerant compression function), is controlled by the control unit 15.

The heater control circuit 30 has a second power module 31 and a second driver 32.

The second power module 31 includes two switching elements (hereinafter referred to as "second switching elements") Q7 and Q8 that control the application of power from the high-voltage power supply HV to the electric heater 5. Like the first switching elements Q1 to Q6 of the motor drive circuit 20, the second switching elements Q7 and Q8 may be IGBTs. In this embodiment, one of the two second switching elements Q7 and Q8, the second switching element Q7, is located closer to the output side (voltage side) of the high-voltage power supply HV than the electric heater 5, and the other second switching element Q8 is located closer to the ground side of the high-voltage power supply HV than the electric heater 5.

The second power module 31 controls (PWM control) the second switching elements Q7 and Q8 to turn on and off the current between the high-voltage power supply HV and the electric heater 5, thereby controlling the temperature of the electric heater 5 and, further, the temperature of the heat medium heated by the electric heater 5.

Like the first driver 22 of the motor drive circuit 20, the second driver 32 drives (switches) the second switching elements Q7 and Q8 (their gates) on and off based on a control signal (PWM signal) from the control unit 15.

In other words, in this embodiment, the operation of the heater control circuit 30 (second switching elements Q7, Q8), and therefore the operation of the electric heater 5 (heat medium heating function), is controlled by the control unit 15.

Now, with reference to Figure 6, we will explain the arrangement of the smoothing capacitor SC, the first switching elements Q1-Q6 of the motor drive circuit 20, and the second switching elements Q7 and Q8 of the heater control circuit 30. Figure 6 is a partial schematic cross-sectional view of the multifunction device 1 (corresponding to the B-B cross-sectional view in Figure 3).

As described above, the electronic circuitry including the motor drive circuit 20 and heater control circuit 30 (and smoothing capacitor SC) is mounted on a circuit board 6 and housed in the third housing space S3. As shown in FIG. 6, the circuit board 6 is attached to, for example, a plurality of board mounting portions 12 provided within the third housing space S3. In this embodiment, each of the plurality of board mounting portions 12 is formed in the shape of a boss that protrudes upward (away from the first housing 2A and the second housing 2B) from the bottom wall 7 of the third housing 2C, and the circuit board 6 is attached to the upper surface of the plurality of board mounting portions 12 with screws 13.

In this embodiment, the smoothing capacitor SC, the first switching elements Q1-Q6 of the motor drive circuit 20, and the second switching elements Q7 and Q8 of the heater control circuit 30 are positioned so that they can be cooled by the refrigerant that flows into the first housing 2A from the refrigerant inlet 8.

Specifically, the smoothing capacitor SC, the first switching elements Q1-Q6 of the motor drive circuit 20, and the second switching elements Q7 and Q8 of the heater control circuit 30 are mounted on the underside of the circuit board 6 attached to the board mounting portion 12 (the surface facing the bottom wall 7 of the third housing 2C), and are arranged so as to be in thermal contact with the first partition 71 that separates the interior of the first housing 2A from the interior of the third housing 2C. Here, "in thermal contact with the first partition 71" means being in a state where heat exchange is possible with the first partition 71, and includes being in direct contact with the first partition 71, being close enough to the first partition 71 so that heat exchange is possible, and being in indirect contact with the first partition 71 via a heat exchange member or the like with high thermal conductivity.

Figure 7 is a block diagram showing the schematic configuration of the control system of the combined device 1 according to this embodiment. As shown in Figure 7, in this embodiment, operation requests (including start requests and stop requests) for the refrigerant compression function and operation requests (including start requests and stop requests) for the heat medium heating function are input to the control unit 15 of the combined device 1 from a higher-level control device (for example, the control device of the vehicle air conditioning system described above).

The control unit 15 also receives the detection results of various detectors, such as the first temperature detector 51, which detects the temperature of the first switching elements Q1 to Q6 or their correlation values, and the second temperature detector 52, which detects the temperature of the second switching elements Q7 and Q8 or their correlation values.

The control unit 15 then supplies control signals to the first driver 22 and/or second driver 32 in response to the input operation request from the higher-level control device and/or the detection results of the various detection units, thereby controlling the operation of the first switching elements Q1 to Q6 (i.e., the operation of the motor drive circuit 20) and/or the second switching elements Q7 and Q8 (i.e., the operation of the heater control circuit 30).

The wiring of the electronic circuit, i.e., the wiring pattern on the circuit board 6, has parasitic inductance. The parasitic inductance of wiring tends to increase as the length of the wiring increases. Furthermore, if the parasitic inductance of the wiring between the smoothing capacitor SC and each of the first switching elements Q1-Q6 of the motor drive circuit 20 and the second switching elements Q7 and Q8 of the heater control circuit 30 in the electronic circuit is L, then the surge voltage ΔV generated when each switching element is switched (turned off) is ΔV = L × di/dt. Here, "di/dt" is the slope of the current flowing through the switching element and depends on the switching (turned off) speed of the switching element.

In order to operate switching elements efficiently, it is better to increase the switching speed of the switching elements. However, increasing the switching speed increases "di/dt" and the surge voltage ΔV. If the surge voltage ΔV exceeds the withstand voltage of the switching element, it may damage the switching element. For this reason, the switching speed of multiple switching elements used in the same circuit is usually limited by the parasitic inductance of the wiring associated with the switching element located farthest from the smoothing capacitor (the switching element with the longest wiring length). In other words, switching elements other than the switching element located farthest from the smoothing capacitor are also set to have slow switching speeds, just like the switching element located farthest from the smoothing capacitor. This results in overall switching losses increasing more than necessary.

In other words, it is difficult to operate all switching elements efficiently while preventing damage to each switching element due to surge voltages.

The multifunction device 1 according to the embodiment employs the following configuration to address the above problem.

(1) First, the drive frequency (switching frequency) of the second switching elements Q7 and Q8 of the heater control circuit 30 is lower than the drive frequency (switching frequency) of the first switching elements Q1 to Q6 of the motor drive circuit 20.

The motor drive circuit 20 (its first switching elements Q1 to Q6) converts the DC voltage from the high-voltage power supply HV into three-phase AC voltage. If the switching frequency of the first switching elements Q1 to Q6 becomes low, distortion may occur in the output waveform. If distortion occurs in the output waveform, stable operation of the electric motor 4 cannot be achieved. For this reason, the switching frequency of the first switching elements Q1 to Q6 of the motor drive circuit 20 must be set to a certain level. For example, the switching frequency of the first switching elements Q1 to Q6 needs to be on the order of kHz or higher.

On the other hand, since the heater control circuit 30 (the second switching elements Q7, Q8) turns on and off the current between the high-voltage power supply HV and the electric heater 5, the switching frequency of the second switching elements Q7, Q8 does not need to be very high. For example, a switching frequency on the order of Hz is sufficient for the second switching elements Q7, Q8.

Therefore, in this embodiment, the switching frequency of the second switching elements Q7 and Q8 is set lower than the switching frequency of the first switching elements Q1 to Q6.

(2) Next, the switching speed of the second switching elements Q7 and Q8 of the heater control circuit 30 is slower than the switching speed of the first switching elements Q1 to Q6 of the motor drive circuit 20.

Slowing the switching speed of a switching element reduces "di/dt." This reduces the surge voltage ΔV that occurs when the switching element switches (turns off). Therefore, slowing the switching speed of a switching element can prevent the surge voltage ΔV that occurs when switching (turns off) from exceeding the withstand voltage of the switching element, preventing damage to the switching element due to the surge voltage. However, slowing the switching speed of a switching element increases switching losses (reducing efficiency).

As described in (1) above, in this embodiment, the switching frequency of the second switching elements Q7, Q8 of the heater control circuit 30 is set lower than the switching frequency of the first switching elements Q1 to Q6 of the motor drive circuit 20. In other words, the second switching elements Q7, Q8 switch less frequently than the first switching elements Q1 to Q6. This means that even if the switching speed of the second switching elements Q7, Q8 is slowed, the increase in switching loss is smaller than when the switching speed of the first switching elements Q1 to Q6 is slowed. In other words, the increase in switching loss overall can be suppressed.

In this embodiment, therefore, the switching speed of the second switching elements Q7, Q8 is set slower than the switching speed of the first switching elements Q1 to Q6. Although not particularly limited, in this embodiment, the gate resistance (not shown) of the second switching elements Q7, Q8 has a higher resistance value than the gate resistance (not shown) of the first switching elements Q1 to Q6 of the motor drive circuit 20, which causes the switching speed of the second switching elements Q7, Q8 to be slower than the switching speed of the first switching elements Q1 to Q6.

(3) In the electronic circuit, the parasitic inductance of the wiring related to the first switching elements Q1 to Q6 of the motor drive circuit 20 is smaller than the parasitic inductance of the wiring related to the second switching elements Q7 and Q8 of the heater control circuit 30.

As described in (2) above, in this embodiment, the switching speed of the second switching elements Q7, Q8 is set slower than the switching speed of the first switching elements Q1 to Q6. Therefore, the "di/dt" of the second switching elements Q7, Q8 is smaller than the "di/dt" of the first switching elements Q1 to Q6. This means that, when considering the surge voltage ΔV (= L × di/dt), the parasitic inductance of the wiring associated with the second switching elements Q7, Q8 may be greater than the parasitic inductance of the wiring associated with the first switching elements Q1 to Q6. In other words, even if the parasitic inductance of the wiring associated with the second switching elements Q7, Q8 is greater than the parasitic inductance of the wiring associated with the first switching elements Q1 to Q6, it is possible to prevent the surge voltage ΔV generated when the second switching elements Q7, Q8 are switched (turned off) from exceeding the breakdown voltage of the second switching elements Q7, Q8.

Therefore, in this embodiment, the electronic circuit is configured so that the parasitic inductance of the wiring related to the first switching elements Q1 to Q6 of the motor drive circuit 20 is smaller than the parasitic inductance of the wiring related to the second switching elements Q7 and Q8 of the heater control circuit 30.

The parasitic inductance of wiring decreases as the wiring length decreases. Therefore, in the electronic circuit of this embodiment, smoothing capacitor SC is positioned closer to the first switching elements Q1-Q6 of the motor drive circuit 20 than to the second switching elements Q7, Q8 of the heater control circuit 30 (see Figure 5). As a result, the length of the wiring related to the first switching elements Q1-Q6 (specifically, the wiring between smoothing capacitor SC and the first switching elements Q1-Q6) is shorter than the length of the wiring related to the second switching elements Q7, Q8 (specifically, the wiring between smoothing capacitor SC and the second switching elements Q7, Q8).

Furthermore, the wider the wiring (thicker the wiring), the smaller the parasitic inductance of the wiring. Therefore, in the electronic circuit of this embodiment, the wiring related to the first switching elements Q1 to Q6 is made wider (thicker) than the wiring related to the second switching elements Q7 and Q8. However, in this embodiment, the wiring related to the second switching elements Q7 and Q8 includes a shared portion with the wiring related to the first switching elements Q1 to Q6. Therefore, in this embodiment, the wiring between the smoothing capacitor SC and the first switching elements Q1 to Q6 (the wiring surrounded by the dashed line in Figure 5) is made wider (thicker) than the portion of the wiring between the smoothing capacitor SC and the second switching elements Q7 and Q8 other than the shared portion, i.e., the wiring between the first switching elements Q1 to Q6 and the second switching elements Q7 and Q8 (the wiring surrounded by the dashed line in Figure 5).

8, on the underside of the circuit board 6 (the surface facing the bottom wall 7 of the third housing 2C), the smoothing capacitor SC is positioned (mounted) closer to the first switching elements Q1 to Q6 of the motor drive circuit 20 than the second switching elements Q7 and Q8 of the heater control circuit 30. Furthermore, on the upper surface of the circuit board 6 (the surface facing the third cover 2F), the lengths of the wiring patterns P1a and P1b between the smoothing capacitor SC and the first switching elements Q1 to Q6 are shorter than the lengths of the wiring patterns P1a+P2a and P1b+P2b between the smoothing capacitor SC and the second switching elements Q7 and Q8. Furthermore, the wiring patterns P1a and P1b between the smoothing capacitor SC and the first switching elements Q1 to Q6 are formed wider than other wiring patterns on the circuit board 6, such as the second wiring patterns P2a and P2b between the first switching elements Q1 to Q6 and the second switching elements Q7 and Q8, and the third wiring patterns P3a and P3b extending from the second switching elements Q7 and Q8 toward the electric heater 5.

The multifunction device 1 according to this embodiment provides the following advantages:

The combined device 1 according to this embodiment includes a first housing (compressor housing) 2A that houses a compression mechanism 3 that compresses a refrigerant and an electric motor 4 that drives the compression mechanism 3 and has a refrigerant inlet 8 and a refrigerant outlet 9; a second housing (heater housing) 2B that houses an electric heater 5 that heats a heat medium and has a heat medium inlet 10 and a heat medium outlet 11; and a third housing (circuit housing) 2C that houses a circuit board 6 on which electronic circuits are mounted, including a motor drive circuit 20 that drives the electric motor 4 and a heater control circuit 30 that controls the electric heater 5. The first housing (compressor housing) 2A, second housing 2B (heater housing), and third housing (circuit housing) 2C are integrally joined together.

This type of combined device 1 can function as both a refrigerant compressor (electric compressor) that compresses a refrigerant and a heat medium heater that heats a heat medium, and can heat the heat medium while compressing the refrigerant. Therefore, the combined device 1 can be applied to the vehicle air conditioning system described above. Furthermore, by applying the combined device 1 to a vehicle air conditioning system, it is possible to reduce the size of the vehicle air conditioning system compared to conventional configurations that have separate electric compressors and heat medium heaters.

In the composite device 1, the motor drive circuit 20 includes first switching elements Q1-Q6 that convert DC voltage into three-phase AC voltage, and the heater control circuit 30 includes second switching elements Q7, Q8 that turn on and off the power to the electric heater 5. The switching frequency (drive frequency) of the second switching elements Q7, Q8 is set lower than the switching frequency (drive frequency) of the first switching elements Q1-Q6, the switching speed of the second switching elements Q7, Q8 is set slower than the switching speed of the first switching elements Q1-Q6, and the electronic circuit is configured so that the parasitic inductance of the wiring related to the first switching elements Q1-Q6 is smaller than the parasitic inductance of the wiring related to the second switching elements Q7, Q8.

Specifically, on the circuit board 6, the smoothing capacitor SC is positioned closer to the first switching elements Q1 to Q6 of the motor drive circuit 20 than the second switching elements Q7 and Q8 of the heater control circuit 30, and the length of the wiring patterns P1a and P1b between the smoothing capacitor SC and the first switching elements Q1 to Q6 is shorter than the length of the wiring patterns P1a + P2a and P1b + P2b between the smoothing capacitor SC and the second switching elements Q7 and Q8. Furthermore, the wiring patterns P1a and P1b between the smoothing capacitor SC and the first switching elements Q1 to Q6 are formed wider than the other wiring patterns on the circuit board 6, including the wiring patterns P2a and P2b between the first switching elements Q1 to Q6 and the second switching elements Q7 and Q8.

As a result, damage to the first switching elements Q1-Q6 and the second switching elements Q7, Q8 due to surge voltages can be prevented without impairing the refrigerant compression function or the heat medium heating function, while an increase in switching loss due to the first switching elements Q1-Q6 and the second switching elements Q7, Q8 can be suppressed. Specifically, for the first switching elements Q1-Q6, by reducing the parasitic inductance of the associated wiring, damage due to surge voltages can be prevented without slowing the switching speed (increasing switching loss). On the other hand, for the second switching elements Q7, Q8, damage due to surge voltages can be prevented by slowing the switching speed, and an increase in switching loss can be suppressed by lowering the switching frequency. As a result, in the combined device 1, it is possible to both prevent damage to the first switching elements Q1-Q6 and the second switching elements Q7, Q8 due to surge voltages and suppress an increase in switching loss due to the first switching elements Q1-Q6 and the second switching elements Q7, Q8.

In addition, in the combined device 1, the refrigerant inlet 8 of the first housing (compressor housing) 2A is located near the first partition 71 that separates the interior of the first housing (compressor housing) 2A from the interior of the third housing (circuit housing) 2C, and within the third housing (circuit housing) 2C, the smoothing capacitor SC, first switching elements Q1 to Q6, and second switching elements Q7 and Q8 are arranged so as to be in thermal contact with the first partition 71.

As a result, the smoothing capacitor SC, first switching elements Q1-Q6, and second switching elements Q7 and Q8 can be effectively cooled by heat exchange with the first partition 71, which can be cooled by the refrigerant flowing into the first housing (compressor housing). In other words, high cooling (heat dissipation) performance is ensured for the smoothing capacitor SC, first switching elements Q1-Q6, and second switching elements Q7 and Q8, resulting in stable operation of the combined device 1.

In the above-described embodiment, the smoothing capacitor SC, the first switching elements Q1 to Q6, and the second switching elements Q7 and Q8 are arranged in thermal contact with the first partition 71. However, this is not limited to this. In the combined device 1, the heat medium inlet 10 of the second housing (heater housing) 2B is located near the second partition 72 that separates the interior of the second housing 2B (heater housing) 2B from the interior of the third housing (circuit housing) 2C, and the second partition 72 can be cooled by the heat medium flowing into the second housing 2B. Therefore, the smoothing capacitor SC, the first switching elements Q1 to Q6, and the second switching elements Q7 and Q8 may be arranged in thermal contact with the second partition 72. Alternatively, portions of the smoothing capacitor SC, the first switching elements Q1 to Q6, and the second switching elements Q7 and Q8 may be arranged in thermal contact with the first partition 71, and the remainders may be arranged in thermal contact with the second partition 72. This also ensures cooling (heat dissipation) for the smoothing capacitor SC, first switching elements Q1 to Q6, and second switching elements Q7 and Q8.

Furthermore, the above description mainly focuses on the case where the combined device 1 is applied to a vehicle air conditioning system. However, this is not limited to this. The combined device 1 can be applied to various devices and systems that use an electric compressor to compress a refrigerant and a heat medium heater to heat a heat medium.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and modifications and variations are possible based on the technical concept of the present invention.

1...combined device, 2...housing, 2A...first housing (compressor housing), 2B...second housing (heater housing), 2C...third housing (circuit housing), 3...compression mechanism, 4...electric motor, 5...electric heater, 6...circuit board, 8...refrigerant inlet, 9...refrigerant outlet, 10...heat medium inlet, 11...heat medium outlet, 15...control unit, 20...motor drive circuit, 30...heater control circuit, Q1-Q6...first switching element (switching element of motor drive circuit), Q7, Q8...second switching element (switching element of heater control circuit), SC...smoothing capacitor

Claims (6)

A composite device having a refrigerant compression function and a heat medium heating function,
a compressor housing that accommodates a compression mechanism that compresses a refrigerant and an electric motor that drives the compression mechanism, and that has a refrigerant inlet through which the refrigerant flows into the compressor housing and a refrigerant outlet through which the refrigerant compressed by the compression mechanism flows out of the compressor housing;
a heater housing that accommodates an electric heater for heating a heat medium and has a heat medium inlet for allowing the heat medium to flow into the heater housing and a heat medium outlet for allowing the heat medium heated by the electric heater to flow out of the heater housing;
a circuit housing that accommodates a circuit board on which electronic circuits including a motor drive circuit that drives the electric motor and a heater control circuit that controls the electric heater are mounted;
Including,
the compressor housing, the heater housing, and the circuit housing are integrally joined together;
the motor drive circuit and the heater control circuit each include a switching element,
a switching frequency of a switching element of the heater control circuit is set lower than a switching frequency of a switching element of the motor drive circuit;
a switching speed of a switching element of the heater control circuit is set slower than a switching speed of a switching element of the motor drive circuit;
the electronic circuit is formed so that a parasitic inductance of wiring relating to the switching elements of the motor drive circuit is smaller than a parasitic inductance of wiring relating to the switching elements of the heater control circuit.
Composite device. a switching element of the motor drive circuit configured to convert a DC voltage from a power supply into an AC voltage;
a switching element of the heater control circuit configured to turn on/off the current flow between the power source and the electric heater;
the electronic circuit further includes a smoothing capacitor that smoothes the DC voltage from the power supply;
On the circuit board, the smoothing capacitor is disposed closer to the switching element of the motor drive circuit than to the switching element of the heater control circuit.
The composite device according to claim 1 . The composite device described in claim 2, wherein, on the circuit board, the length of the wiring pattern between the smoothing capacitor and the switching element of the motor drive circuit is shorter than the length of the wiring pattern between the smoothing capacitor and the switching element of the heater control circuit. The composite device described in claim 2, wherein the wiring pattern between the smoothing capacitor and the switching element of the motor drive circuit on the circuit board is formed wider than other wiring patterns. an interior of the compressor housing and an interior of the circuit housing are separated by a first partition portion, and the refrigerant inlet of the compressor housing is provided in the vicinity of the first partition portion,
Within the circuit housing, the smoothing capacitor, the switching element of the motor drive circuit, and the switching element of the heater control circuit are arranged to be in thermal contact with the first partition portion.
The composite device according to any one of claims 2 to 4. an interior of the heater housing and an interior of the circuit housing are separated by a second partition, and the heat medium inlet of the heater housing is provided near the second partition,
Within the circuit housing, the smoothing capacitor, the switching element of the motor drive circuit, and the switching element of the heater control circuit are arranged to be in thermal contact with the second partition portion.
The composite device according to any one of claims 2 to 4.