Cooler and power conversion device

Abstract

A fourth refrigerant passage (740) is defined by a fourth top surface on which a third communication hole (753) opens, a fourth bottom surface (746) that is positioned below the fourth top surface in the Z direction and on which a discharge pipe (702) opens, and an annular surface (747) that connects the fourth top surface and the fourth bottom surface (746). The annular surface has a fourth left surface (741) and a fourth right surface 742 that are separated in the X direction, and a fourth front surface (743) and a fourth rear surface (744) that are separated in the Y direction. The fourth left surface, the fourth rear surface, the fourth right surface, and the fourth front surface are connected in this order around the Z direction. Refrigerant that travels from a second side surface toward a first side surface in the X direction flows into the third communication hole. The opening of a third connection hole is located closer to the fourth right surface in the X direction than the opening of the discharge pipe. The opening of the discharge pipe is located closer to the fourth rear surface in the Y direction than the opening of the third communication hole.

Description

Cooler and power conversion device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-111133 filed in Japan on July 10, 2024, and the contents of the original application are incorporated by reference in their entirety.

[0002] The disclosure described herein relates to a cooler and a power conversion device.

[0003] Patent Document 1 discloses an electric work vehicle that is provided with a cooling path for cooling an inverter.

[0004] Japanese Patent Application Laid-Open No. 2023-95635

[0005] In the electric work vehicle of Patent Document 1, a refrigerant flows through the hollow portion of the cooling passage. The refrigerant flows through the cooling passage by an electric pump. The refrigerant flows in the extension direction of the cooling passage, but if the extension direction is changed from a linear direction, the refrigerant collides with the wall surface that defines the cooling flow path, which reduces the flow rate of the refrigerant.

[0006] An object of the present disclosure is to provide a cooler and a power conversion device in which a decrease in the flow velocity of a refrigerant is suppressed.

[0007] The disclosed aspect is a cooler for cooling a power conversion circuit, having a cooling flow path defined by an upper surface having a first inlet through which a refrigerant flows, a lower surface located vertically lower than the first inlet and having a second inlet through which the refrigerant that has flowed into the first inlet flows, and an annular surface connecting the upper surface and the lower surface, wherein the annular surface has a first side surface and a second side surface that are spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side surface and a fourth side surface that are spaced apart in a vertical direction perpendicular to the horizontal direction, and the first side surface, the fourth side surface, the second side surface, and the third side surface are connected in order around the vertical direction to form an annular surface, and the refrigerant flows into the first inlet from the second side surface toward the first side surface in the horizontal direction, and the first inlet is located closer to the second side surface in the horizontal direction than the second inlet, and the second inlet is located closer to the fourth side surface in the vertical direction than the first inlet.

[0008] The disclosed aspect is a power conversion device having a power conversion circuit and a cooler that cools the power conversion circuit, wherein the cooler has a cooling flow path defined by an upper surface having a first inlet through which a refrigerant flows, a lower surface located vertically lower than the first inlet and having a second inlet through which the refrigerant that has flowed into the first inlet flows, and an annular surface connecting the upper surface and the lower surface, wherein the annular surface has a first side surface and a second side surface that are spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side surface and a fourth side surface that are spaced apart in a vertical direction perpendicular to the vertical and horizontal directions, and the first side surface, the fourth side surface, the second side surface, and the third side surface are connected in order around the vertical direction to form an annular surface, wherein the refrigerant flows into the first inlet in the horizontal direction from the second side surface toward the first side surface, and the first inlet is located closer to the second side surface in the horizontal direction than the second inlet, The second inlet is located closer to the fourth side surface than the first inlet in the vertical direction.

[0009] This allows the refrigerant that flows into the cooling channel from the first inlet to more easily flow horizontally toward the first side surface. The refrigerant then more easily flows vertically toward the second inlet, which is located closer to the fourth side surface than the first inlet. As a result, the refrigerant is more likely to swirl within the cooling channel before flowing vertically from the first inlet to the second inlet. This increases the flow rate of the refrigerant within the cooling channel. A decrease in the flow rate of the refrigerant is suppressed.

[0010] The reference numbers in parentheses above merely indicate the corresponding relationship with the configurations described in the embodiments below, and do not in any way limit the technical scope.

[0011] 7 is a circuit diagram for explaining an in-vehicle system. 10 is a perspective view for explaining a case and a refrigerant passage. 11 is a cross-sectional view taken along line III-III in FIG. 2. 12 is a cross-sectional view taken along line IV-IV in FIG. 2. 13 is a schematic view for explaining a refrigerant passage. 14 is a top view for explaining a third refrigerant passage. 15 is a side view for explaining a fourth refrigerant passage. 16 is a plan view taken from the direction of the arrows attached to line VIII-VIII in FIG. 7. 17 is a plan view taken from the direction of the arrows attached to line IX-IX in FIG. 7. 18 is a side view for explaining a fourth refrigerant passage. 19 is a plan view taken from the direction of the arrows attached to line XI-XI in FIG.

[0012] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. Portions corresponding to matters described in the previous embodiments may be assigned the same reference numerals in the subsequent embodiments, and duplicated descriptions may be omitted. When only a portion of the configuration is described in each embodiment, the description of the previous embodiment may be applied to the remaining portions of the configuration.

[0013] In each embodiment, it is possible to combine parts that are specifically expressly permitted to be combined with each other. Furthermore, even if it is not explicitly stated that a combination is possible, it is also possible to partially combine multiple embodiments, an embodiment and a variation, or multiple variation embodiments, as long as there is no particular problem with the combination.

[0014] In the following description, the three mutually orthogonal directions are referred to as the X, Y, and Z directions. The X, Y, and Z directions are linear directions. In the drawings, the "directions" are omitted and the directions are simply shown as X, Y, and Z. The flow direction of the refrigerant, which will be described later, is indicated by solid arrows in the drawings.

[0015] When the present disclosure is mounted on a vehicle, the X direction is along the left-right direction of the vehicle. The Y direction is along the forward and backward direction of the vehicle. The Z direction is along the vertical direction of the vehicle. When the vehicle is parked on a horizontal surface, the plane defined by the X direction and the Y direction is along the horizontal direction. The Z direction is along the vertical direction. In the following, embodiments will be described on the assumption that the plane defined by the X direction and the Y direction is along the horizontal direction and the Z direction is along the vertical direction. The X direction corresponds to the horizontal direction. The Y direction corresponds to the vertical direction.

[0016] First Embodiment In-Vehicle System First, an in-vehicle system 100 to which a power conversion device 300 is applied will be outlined with reference to Fig. 1. The in-vehicle system 100 is a system for an electric vehicle. The in-vehicle system 100 has a battery 200, a power conversion device 300, and a motor 400.

[0017] The in-vehicle system 100 also has multiple ECUs (not shown). These multiple ECUs transmit and receive signals to each other via bus wiring. The multiple ECUs cooperate to control the electric vehicle. The power running and regeneration of the motor 400 are controlled according to the SOC of the battery 200 through the control of the multiple ECUs. ECU stands for electronic control unit. SOC stands for state of charge.

[0018] The ECU has at least one central processing unit (CPU) and at least one memory device (MMR) as a recording medium for recording programs and data. The ECU is provided by a microcomputer equipped with a computer-readable recording medium. The recording medium is a non-transitory tangible recording medium that non-temporarily stores a computer-readable program. The recording medium can be provided as a semiconductor memory, a magnetic disk, or the like.

[0019] Battery 200 has a plurality of secondary batteries. These secondary batteries are connected in series to form a battery stack. The SOC of this battery stack corresponds to the SOC of battery 200. The secondary batteries may be solid-state batteries, lithium-ion secondary batteries, nickel-metal hydride secondary batteries, organic radical batteries, or the like.

[0020] The power conversion device 300 performs power conversion between the battery 200 and the motor 400. The power conversion device 300 converts DC power from the battery 200 into AC power. The power conversion device 300 converts AC power generated by power generation (regeneration) by the motor 400 into DC power.

[0021] The motor 400 is connected to an axle of the electric vehicle (not shown). The rotational energy (power) of the motor 400 is transmitted to the running wheels of the electric vehicle via the axle. Conversely, the rotational energy of the running wheels is transmitted to the motor 400 via the axle.

[0022] The motor 400 is powered by AC power supplied from the power converter 300. This provides propulsion force to the running wheels. The motor 400 also regenerates power using rotational energy transmitted from the running wheels. The regenerated AC power is converted into DC power by the power converter 300. This DC power is supplied to the battery 200 and various electrical loads mounted on the electric vehicle.

[0023] <Power Conversion Apparatus> Next, the power conversion apparatus 300 will be described. The power conversion apparatus 300 has a power conversion circuit 500 and a case 600. The power conversion circuit 500 has the components shown in Fig. 1. The case 600 has the components shown in Fig. 2.

[0024] 3 and 4, the components of the power conversion circuit 500 are housed in a case 600. The case 600 is provided with a refrigerant passage 700 through which a refrigerant passes. The refrigerant passing through this refrigerant passage 700 suppresses a rise in temperature of the power conversion circuit 500. The case 600 corresponds to a cooler.

[0025] <Power Conversion Circuit> The power conversion circuit 500 includes an inverter 510. The inverter 510 converts DC power from the battery 200 into AC power. This AC power is supplied to the motor 400. The inverter 510 also converts AC power generated by the motor 400 into DC power. This DC power is supplied to the battery 200. The power conversion circuit 500 may also include a converter that steps up or steps down the input voltage and outputs it.

[0026] The power conversion circuit 500 has an N bus bar 501 and a P bus bar 502. The battery 200 is connected to the N bus bar 501 and the P bus bar 502. The N bus bar 501 is connected to the negative electrode of the battery 200. The P bus bar 502 is connected to the positive electrode of the battery 200.

[0027] The power conversion circuit 500 also has a U-phase bus bar 503, a V-phase bus bar 504, and a W-phase bus bar 505. The inverter 510 and the motor 400 are electrically connected via the U-phase bus bar 503, the V-phase bus bar 504, and the W-phase bus bar 505. In Fig. 1, the connection portions of the various bus bars are indicated by white circles. These connection portions are electrically connected by, for example, bolts or welding.

[0028] <Inverter> The inverter 510 has a smoothing capacitor 520 and a switch group 530. The smoothing capacitor 520 and the switch group 530 are electrically connected to an N bus bar 501 and a P bus bar 502.

[0029] The smoothing capacitor 520 is housed in a capacitor case 521, which is shown schematically in FIG. 3. The capacitor case 521 is made of an insulating resin material. The N bus bar 501 and a portion of the P bus bar 502 are housed in the capacitor case 521. The capacitor case 521 is fixed to the case 600.

[0030] The switch group 530 includes a U-phase switch module 531, a V-phase switch module 532, and a W-phase switch module 533. These three-phase switch modules have a high-side switch 541 and a low-side switch 542. The three-phase switch module also has a high-side diode 541a and a low-side diode 542a.

[0031] The switches and diodes included in the three-phase switch module are housed in a switch case 543, which is shown schematically in Figures 3 and 4. The switch case 543 is made of an insulating resin material. In this embodiment, the switches and diodes included in the three-phase switch module are housed in one switch case 543. Of course, it is also possible to employ a configuration in which the switches and diodes included in the three-phase switch module are housed individually in three switch cases 543.

[0032] In this embodiment, n-channel IGBTs are used as the high-side switch 541 and the low-side switch 542. As shown in Fig. 1, the emitter electrode of the high-side switch 541 and the collector electrode of the low-side switch 542 are connected together, thereby connecting the high-side switch 541 and the low-side switch 542 in series.

[0033] The cathode electrode of the high-side diode 541a is connected to the collector electrode of the high-side switch 541. The anode electrode of the high-side diode 541a is connected to the emitter electrode of the high-side switch 541. As a result, the high-side diode 541a is connected in anti-parallel to the high-side switch 541.

[0034] Similarly, the cathode electrode of the low-side diode 542a is connected to the collector electrode of the low-side switch 542. The anode electrode of the low-side diode 542a is connected to the emitter electrode of the low-side switch 542. As a result, the low-side diode 542a is connected in anti-parallel to the low-side switch 542.

[0035] As described above, the switch is housed in switch case 543. Exposed from switch case 543 are a tip of collector terminal 540a connected to the collector electrode of high-side switch 541 and a tip of output terminal 540b connected to the midpoint between high-side switch 541 and low-side switch 542. Also exposed from switch case 543 are a tip of emitter terminal 540c connected to the emitter electrode of low-side switch 542 and a tip of gate terminal 540d connected to the gate electrodes of high-side switch 541 and low-side switch 542.

[0036] 1, the collector terminal 540a is connected to the P bus bar 502. The emitter terminal 540c is connected to the N bus bar 501. With this electrical connection, the high-side switch 541 and the low-side switch 542 are connected in series in this order from the P bus bar 502 to the N bus bar 501.

[0037] A U-phase bus bar 503 is connected to an output terminal 540b of the U-phase switch module 531. A V-phase bus bar 504 is connected to an output terminal 540b of the V-phase switch module 532. A W-phase bus bar 505 is connected to an output terminal 540b of the W-phase switch module 533.

[0038] The motor 400 has a U-phase stator coil, a V-phase stator coil, and a W-phase stator coil. A U-phase bus bar 503 is electrically connected to the U-phase stator coil. A V-phase bus bar 504 is electrically connected to the V-phase stator coil. A W-phase bus bar 505 is electrically connected to the W-phase stator coil. This electrically connects the inverter 510 and the motor 400.

[0039] The gate terminals 540d of the high-side switches 541 and low-side switches 542 included in the U-phase switch modules 531 to W-phase switch modules 533 are connected to the gate driver.

[0040] The gate driver, together with some of the multiple ECUs described above, is included in the circuit board 550 shown in FIG. 1. The ECU generates a control signal and outputs it to the gate driver. The gate driver amplifies the control signal and outputs it to gate terminal 540d. This allows the high-side switch 541 and low-side switch 542 to be controlled to open or close by the ECU. Note that the board on which the gate driver is mounted and the board on which the ECU is mounted may be separate.

[0041] The ECU generates a pulse signal as a control signal. The ECU adjusts the on-duty ratio and frequency of this pulse signal. The on-duty ratio and frequency are determined based on the outputs of various sensors.

[0042] When motor 400 is powered, a control signal is output from the ECU to PWM-control high-side switch 541 and low-side switch 542 of the three-phase switch module. This generates a three-phase AC current in power conversion circuit 500. This three-phase AC current is input to three-phase stator coils. This generates a three-phase rotating magnetic field in the three-phase stator coils. The interaction between this three-phase rotating magnetic field and the magnetic field generated by the rotor of motor 400 generates a rotational torque in the rotor.

[0043] When the motor 400 generates (regenerates) electricity using the rotational energy of the running wheels, the ECU, for example, stops outputting the control signal. As a result, the AC power generated by the power generation passes through the diodes of the three-phase switch module. As a result, the AC power is converted into DC power.

[0044] The types of switch elements included in the U-phase switch module 531 to W-phase switch module 533 are not particularly limited, and MOSFETs, for example, can be used. The switches, diodes, and other semiconductor elements included in these three-phase switch modules can be manufactured using semiconductors such as Si and wide-gap semiconductors such as SiC. The constituent materials of the semiconductor elements are not particularly limited.

[0045] Furthermore, the number of high-side switches 541 and low-side switches 542 included in the three-phase switch module is not limited to one. At least one of the three-phase switch modules may include a plurality of high-side switches 541 connected in parallel and a plurality of low-side switches 542 connected in parallel. The number of switches connected in parallel can be determined based on the rated current of the switches and the amount of current that can be passed through the power conversion circuit 500, etc.

[0046] <Case> The case 600 is made of a high-permeability material that has a higher magnetic permeability than air. Specifically, the case 600 is made of a metal material such as alumina or iron. The case 600 houses the capacitor case 521 and the switch case 543. The case 600 houses the components of the power conversion circuit 500 shown in FIG. 1 . The case 600 also houses a current sensor (not shown) and the like.

[0047] As shown schematically in FIGS. 2 to 4, the case 600 has, as its major components, a first case 610, a second case 620, and a third case 630. The first case 610 and the third case 630 are arranged side by side in the Z direction with the second case 620 interposed therebetween. The first case 610 and the second case 620 are connected via a seal, and the second case 620 and the third case 630 are connected via a seal. This forms a refrigerant passage 700 inside the case 600. The refrigerant passage 700 is mainly defined by the walls of the first case 610, the second case 620, and the third case 630. In addition to the case 600, FIGS. 2 and 3 also show a capacitor case 521 and a switch case 543.

[0048] The first case 610 has a first upper surface 610a and a first lower surface 610b aligned in the Z direction. The second case 620 has a second upper surface 620a and a second lower surface 620b aligned in the Z direction. The third case 630 has a third upper surface 630a and a third lower surface 630b aligned in the Z direction.

[0049] The first case 610 and the second case 620 are connected in a manner that the first upper surface 610a and the second lower surface 620b face each other in the Z direction. The second case 620 and the third case 630 are connected in a manner that the second upper surface 620a and the third lower surface 630b face each other in the Z direction.

[0050] 3 and 4 , the first upper surface 610a and the second lower surface 620b are partially undulating in the Z direction. Furthermore, the third lower surface 630b is along a plane perpendicular to the Z direction, but the second upper surface 620a is partially undulating in the Z direction. The first upper surface 610a and the second lower surface 620b are partially in contact with each other, and these two surfaces form a portion of the refrigerant passage 700. The second upper surface 620a and the third lower surface 630b are partially in contact with each other, and these two surfaces form a portion of the refrigerant passage 700.

[0051] Further, a through hole penetrating second upper surface 620a and second lower surface 620b is formed in second case 620. This through hole also constitutes part of refrigerant passage 700. This through hole communicates between the space defined by first upper surface 610a and second lower surface 620b and the space defined by second upper surface 620a and third lower surface 630b.

[0052] As shown in FIG. 5 , an input pipe 701 and a discharge pipe 702 are connected to a refrigerant passage 700. The input pipe 701 and the discharge pipe 702 are connected to a pump (not shown). The refrigerant that flows from the input pipe 701 into the refrigerant passage 700 exchanges heat with the components of the power conversion circuit 500 housed in the case 600. The refrigerant that has exchanged heat is returned to the pump via the discharge pipe 702. The temperature of the refrigerant returned to the pump is lowered by a cooler such as a radiator. The lowered temperature refrigerant is supplied back to the input pipe 701. The input pipe 701 is formed by the second case 620, and the discharge pipe 702 is formed by the third case 630. However, the input pipe 701 and the discharge pipe 702 may be formed separately from the case 600.

[0053] <Refrigerant Passage> The refrigerant passage 700 has a first refrigerant passage 710, a second refrigerant passage 720, a third refrigerant passage 730, and a fourth refrigerant passage 740. The refrigerant passage 700 also has a first communication hole 751, a second communication hole 752, and a third communication hole 753.

[0054] The first upper surface 610a and the second lower surface 620b define the first refrigerant passage 710, the second refrigerant passage 720, and the fourth refrigerant passage 740. The first communication hole 751 is also defined by the first upper surface 610a and the second lower surface 620b.

[0055] The third refrigerant passage 730 is a space defined by the second upper surface 620a and the third lower surface 620b. The first communication hole 751 and the second communication hole 752 are through holes that penetrate the second upper surface 620a and the second lower surface 620b of the second case 620.

[0056] An input pipe 701 is connected to a first refrigerant passage 710. The first refrigerant passage 710 and the second refrigerant passage 720 communicate with each other via a first communication hole 751. The second refrigerant passage 720 and the third refrigerant passage 730 communicate with each other via a second communication hole 752. The third refrigerant passage 730 and the fourth refrigerant passage 740 communicate with each other via a third communication hole 753. An exhaust pipe 702 is connected to the fourth refrigerant passage 740.

[0057] Due to this mechanical configuration, the refrigerant supplied to the input pipe 701 passes through the first refrigerant passage 710, the first communication hole 751, the second refrigerant passage 720, the second communication hole 752, the third refrigerant passage 730, the third communication hole 753, and the fourth refrigerant passage 740 in that order, before being discharged into the discharge pipe 702.

[0058] The first refrigerant passage 710 is located upstream in the direction of refrigerant flow, and the fourth refrigerant passage 740 is located downstream. As the refrigerant travels from upstream to downstream, it exchanges heat with various components of the power conversion circuit 500 housed in the case 600. Therefore, the temperature of the refrigerant is higher downstream than upstream.

[0059] The capacitor case 521 is provided on the second upper surface 620a of the second case 620. The first refrigerant passage 710 and the capacitor case 521 are aligned in the Z direction. The capacitor case 521 is pressed against the second case 620 by bolts or the like. This allows for active thermal conduction between the capacitor case 521 and the second case 620. The rise in temperature of the smoothing capacitor 520 housed in the capacitor case 521 is suppressed mainly by the refrigerant passing through the first refrigerant passage 710.

[0060] The refrigerant that has exchanged heat with smoothing capacitor 520 flows from first refrigerant passage 710 to second refrigerant passage 720. This refrigerant flows from second refrigerant passage 720 to third refrigerant passage 730. In this way, second refrigerant passage 720 functions to relay between first refrigerant passage 710 and third refrigerant passage 730.

[0061] The switch case 543 is provided on the third upper surface 630a of the third case 630. The third refrigerant passage 730 and the switch case 543 are aligned in the Z direction. The switch case 543 is pressed against the third case 630 by a fixing member (not shown). This allows active thermal conduction between the switch case 543 and the third case 630. The rise in temperature of the switch group 530 housed in the switch case 543 is suppressed mainly by the refrigerant passing through the third refrigerant passage 730.

[0062] The refrigerant that has exchanged heat with switch group 530 flows from third refrigerant passage 730 to fourth refrigerant passage 740. This refrigerant is returned to the pump. The temperature of this refrigerant is lowered by a cooler and is supplied to first refrigerant passage 710 again.

[0063] <Refrigerant Flow Speed> When the refrigerant passes through the refrigerant passage 700, the flow direction changes depending on the shape of the refrigerant passage 700. This causes a pressure loss, which reduces the refrigerant flow speed. As a result, there is a concern that the cooling effect of the refrigerant on the power conversion circuit 500 may be reduced.

[0064] <Refrigerant Passage> In order to solve this problem, the present disclosure has devised a shape for the refrigerant passage 700. The refrigerant passage 700 will be described in detail below.

[0065] 5, the input pipe 701, the first refrigerant passage 710, the second refrigerant passage 720, and the third refrigerant passage 730 are aligned in order in the Y direction. The fourth refrigerant passage 740 and the second refrigerant passage 720 are aligned in the X direction.

[0066] In the Z direction, the first refrigerant passage 710 is located below the second refrigerant passage 720, the third refrigerant passage 730, and the fourth refrigerant passage 740. The second refrigerant passage 720 is located between the first refrigerant passage 710 and the third refrigerant passage 730 in the Z direction. The third refrigerant passage 730 is located above the first refrigerant passage 710, the second refrigerant passage 720, and the fourth refrigerant passage 740 in the Z direction. The position of the fourth refrigerant passage 740 in the Z direction is the same as the position of the second refrigerant passage 720 in the Z direction.

[0067] The first refrigerant passage 710 and the second refrigerant passage 720 are not aligned in the Z direction, but are aligned in the Y direction. The second refrigerant passage 720 and the third refrigerant passage 730 are aligned in the Z direction. The third refrigerant passage 730 and the fourth refrigerant passage 740 are aligned in the Z direction. Furthermore, the fourth refrigerant passage 740 and the discharge pipe 702 are aligned in the Z direction.

[0068] A refrigerant flows through the refrigerant passage 700, but because the refrigerant is a fluid, its flow direction is not uniquely determined. However, for ease of explanation, in this disclosure, the direction in which the refrigerant is expected to flow will be referred to as the refrigerant flow direction. When the refrigerant passage 700 is filled with refrigerant, the refrigerant flowing through the refrigerant passage 700 is expected to flow mainly along the extension direction of the wall surfaces that define the refrigerant passage 700. Of course, this refrigerant flow direction is the same for the input pipe 701 and the discharge pipe 702.

[0069] The input pipe 701 extends in the Y direction. Therefore, the flow direction of the refrigerant that flows into this input pipe 701 is also the Y direction. The refrigerant flowing in the Y direction flows into the first refrigerant passage 710.

[0070] The first refrigerant passage 710 extends in the Y direction. The first refrigerant passage 710 is short in the Z direction but wide in the X direction. The width of the first refrigerant passage 710 in the X direction gradually widens, remains constant, and then gradually narrows as it moves from the input pipe 701 to the first communicating hole 751. In this way, the shape of the first refrigerant passage 710 changes as it moves from the input pipe 701 to the first communicating hole 751. However, the flow path cross-sectional area of ​​the first refrigerant passage is constant.

[0071] The refrigerant flowing through the first refrigerant passage 710 flows mainly in the Y direction. At the same time, as the refrigerant flowing through the first refrigerant passage 710 travels from the input pipe 701 toward the second refrigerant passage 720, it flows away from the input pipe 701 in the X direction, and after reaching a constant flow, it flows gradually toward the first communicating hole 751 in the X direction.

[0072] The refrigerant flowing in the Y and X directions flows into the second refrigerant passage 720 through the first communication holes 751. The shape of the first communication holes 751 is the same as the shape of the first refrigerant passage 710 on the second refrigerant passage 720 side.

[0073] 3 and 5 , the length of the first communication hole 751 in the Y direction is shorter than its lengths in the X and Z directions. The first communication hole 751 opens to the wall surface that defines the first refrigerant passage 710 and the wall surface that defines the second refrigerant passage 720, and these two opening shapes are identical. In this embodiment, the positions of these two openings in the X and Z directions are identical.

[0074] Due to this configuration, the flow direction of the refrigerant flowing through the first communication hole 751 is unlikely to be corrected by the wall surfaces that form the first communication hole 751. Refrigerant flowing in the Y direction and X direction described above flows into the second refrigerant passage 720. Note that the first communication hole 751 is merely defined for convenience in order to separate the first refrigerant passage 710 and the second refrigerant passage 720, and the first refrigerant passage 710 and the second refrigerant passage 720 may also be configured to be continuously connected.

[0075] The second refrigerant passage 720 extends in both the Y direction and the Z direction. The flow path cross-sectional area of ​​the second refrigerant passage 720 gradually narrows in the Y direction as it moves away from the first refrigerant passage 710. The width of the second refrigerant passage 720 in the X direction gradually narrows as it moves from the first refrigerant passage 710 toward the third refrigerant passage 730.

[0076] Due to this shape, the refrigerant flowing through the second refrigerant passage 720 flows in the Y direction, the Z direction, and the X direction. The refrigerant flowing through the second refrigerant passage 720 flows in the Y direction while resisting gravity. At the same time, as the refrigerant flowing through the second refrigerant passage 720 moves from the first communication hole 751 to the second communication hole 752 in the Y direction and the Z direction, it gradually moves closer to the second communication hole 752 in the X direction.

[0077] The refrigerant flowing in the Y, Z, and X directions flows into the second communication hole 752. The second communication hole 752 extends in the Z direction. The second communication hole 752 is aligned with the switch case 543 in the Z direction. The second communication hole 752 opens into the wall surface defining the second refrigerant passage 720 and the wall surface defining the third refrigerant passage 730, and these two opening shapes are identical. The positions of these two openings in the X and Y directions are identical. Therefore, the flow direction of the refrigerant that flows from the second refrigerant passage 720 into the second communication hole 752 is changed from the Y, Z, and X directions to mainly the Z direction. The refrigerant flowing in the Z direction flows up into the third refrigerant passage 730.

[0078] The third refrigerant passage 730 extends in the X direction. The flow path cross-sectional area of ​​the third refrigerant passage 730 is constant. The third refrigerant passage 730 is short in the Z direction but wide in the Y direction. The width of the third refrigerant passage 730 in the Y direction is constant. The opening locations of the second communication holes 752 and the third communication holes 753 in the third refrigerant passage 730 are separated in the X direction and located at the same position in the Y direction. Therefore, the refrigerant flowing through the third refrigerant passage 730 flows mainly in the X direction. The refrigerant flowing through this third refrigerant passage 730 in the X direction flows down into the third communication holes 753.

[0079] The third communication hole 753 extends in the Z direction. The third communication hole 753 opens to the wall surface that defines the third refrigerant passage 730 and the wall surface that defines the fourth refrigerant passage 740. These two openings have the same shape and are positioned in the same way in the X and Y directions.

[0080] The fourth refrigerant passage 740 extends in the Z direction. The refrigerant flows down into this fourth refrigerant passage 740 from the third communication hole 753. The discharge pipe 702 is connected to the fourth refrigerant passage 740. The refrigerant that flows into the fourth refrigerant passage 740 flows into the discharge pipe 702. The refrigerant that flows into the discharge pipe 702 is returned to the pump as described above. Note that the refrigerant may be made to flow in an annular buffer space between the discharge pipe 702 and the pump. This buffer space is defined in the case 600.

[0081] 3 and 4 , the second communication hole 752 extends in the Z direction. The second communication hole 752 opens into a region in the second lower surface 620b that defines the second refrigerant passage 720. At the same time, the second communication hole 752 opens into a region in the second upper surface 620a that defines the third refrigerant passage 730. The two opening shapes of the second communication holes 752 are the same.

[0082] As shown in FIG. 6, the opening shape of the second communication hole 752 is defined by a left edge 752a and a right edge 752b spaced apart in the X direction, and a front edge 752c and a rear edge 752d spaced apart in the Y direction.

[0083] The left edge 752a is farther away from the fourth refrigerant passage 740 in the X direction than the right edge 752b. The front edge 752c is located closer to the first refrigerant passage 710 in the Y direction than the rear edge 752d. The left edge 752a, the rear edge 752d, the right edge 752b, and the front edge 752c are connected in order to form the opening of the annular second communication hole 752. The opening of the second communication hole 752 is longer in the Y direction than in the X direction.

[0084] The front edge 752c and the rear edge 752d extend in the X direction. The rear edge 752d is shorter in length in the X direction than the front edge 752c.

[0085] The left edge 752a extends in the Y direction. The right edge 752b extends in a direction inclined relative to the Y direction. The right edge 752b is inclined such that the distance between the right edge 752b and the left edge 752a in the X direction gradually increases from the rear edge 752d to the front edge 752c in the Y direction.

[0086] Due to this opening shape, the refrigerant that flows up from the second communication hole 752 to the third refrigerant passage 730 flows more in the X direction than in the Y direction, as shown by the solid arrow in Figure 6. The refrigerant that flows up to the third refrigerant passage 730 flows in the third refrigerant passage 730 toward the third communication hole 753 that is aligned with but spaced apart from the second communication hole 752 in the X direction.

[0087] <Third Refrigerant Passage> As described above, third refrigerant passage 730 is defined by second upper surface 620a of second case 620 and third lower surface 630b of third case 630. In the following, to simplify the description of third refrigerant passage 730, the wall surfaces defining third refrigerant passage 730 are divided into six surfaces. That is, the wall surfaces defining third refrigerant passage 730 are divided into a third left surface 731 and a third right surface 732 that are spaced apart from each other in the X direction, a third front surface 733 and a third rear surface 734 that are spaced apart from each other in the Y direction, and a third top surface 735 and a third bottom surface 736 that are spaced apart from each other in the Z direction.

[0088] The third left surface 731 is farther from the fourth refrigerant passage 740 in the X direction than the third right surface 732. The third front surface 733 is located closer to the first refrigerant passage 710 in the Y direction than the third rear surface 734. The third top surface 735 is located higher than the third bottom surface 736 in the Z direction.

[0089] The third left surface 731, the third rear surface 734, the third right surface 732, and the third front surface 733 are connected in this order to form a third annular surface 737. An opening located on the upper side of the third annular surface 737 in the Z direction is closed by a third top surface 735, and an opening located on the lower side of the third annular surface 737 in the Z direction is closed by a third bottom surface 736.

[0090] The third refrigerant passage 730 corresponds to the inlet flow path. The third left surface 731 corresponds to the left surface. The third right surface 732 corresponds to the right surface. The third front surface 733 corresponds to the front surface. The third rear surface 734 corresponds to the rear surface. The third top surface 735 corresponds to the top surface. The third bottom surface 736 corresponds to the bottom surface. The third annular surface 737 corresponds to the partition surface.

[0091] A second communication hole 752 opens on the third bottom surface 736 toward the third left surface 731. A third communication hole 753 opens on the third bottom surface 736 toward the third right surface 732. The opening of the second communication hole 752 and the opening of the third communication hole 753 are lined up but spaced apart in the X direction. In the X direction, there is a gap between the opening of the second communication hole 752 and the third left surface 731, and there is a gap between the opening of the third communication hole 753 and the third right surface 732. The second communication hole 752 corresponds to an upstream port.

[0092] Furthermore, the opening of the second communication hole 752 and the opening of the third communication hole 753 are located toward the center in the Y direction between the third front surface 733 and the third rear surface 734. These two openings are not located at the ends in the Y direction on the third front surface 733 side or the third rear surface 734 side. Gaps are defined between the two openings and the third front surface 733, and between the two openings and the third rear surface 734.

[0093] The length and position of the central side of the third refrigerant passage 730 in the Y direction are determined by the Y direction lengths and positions of the openings of the second communication hole 752 and the third communication hole 753. The Y direction length of the central side of the third refrigerant passage 730 is equal to or greater than one-third of the Y direction distance between the third front surface 733 and the third rear surface 734, and is less than one-third of the Y direction distance at the two end sides. In this embodiment, the Y direction length of the central side of the third refrigerant passage 730 is longer than the sum of the Y direction lengths of the two end sides. However, the Y direction length of the central side of the third refrigerant passage 730 may be equal to the sum of the Y direction lengths of the two end sides. The Y direction length of the central side of the third refrigerant passage 730 may also be shorter than the sum of the Y direction lengths of the two end sides.

[0094] <Heat Dissipation Fins> As shown in Figures 3 and 4, a plurality of heat dissipation fins 738 are formed on the third top surface 735. In Figure 6, these heat dissipation fins 738 are indicated by dashed lines. The heat dissipation fins 738 are arranged at intervals in a direction perpendicular to the Z direction. Some of the heat dissipation fins 738 are aligned with the second communication holes 752 in the Z direction.

[0095] The distribution density of the multiple heat dissipation fins 738 is higher on the central side between the third front surface 733 and the third rear surface 734 in the Y direction than on the end sides of the third front surface 733 and the third rear surface 734. In this embodiment, the multiple heat dissipation fins 738 are located only on the central side between the third front surface 733 and the third rear surface 734. The multiple heat dissipation fins 738 are not located on the end sides of the third front surface 733 and the third rear surface 734.

[0096] The plurality of heat dissipation fins 738 are spaced apart in the Y direction from the third front surface 733. The plurality of heat dissipation fins 738 are spaced apart in the Y direction from the third rear surface 734. The shortest distance between the plurality of heat dissipation fins 738 is longer than the shortest distance between any two adjacent heat dissipation fins 738 among the plurality of heat dissipation fins 738.

[0097] 6 , the refrigerant that has flowed from the second communication hole 752 into the third refrigerant passage 730 tends to flow in the X direction rather than the Y direction due to the opening shape of the second communication hole 752 at the third bottom surface 736. This refrigerant actively tries to flow in the X direction from the third left surface 731 to the third right surface 732.

[0098] Naturally, this refrigerant attempts to flow through the center and the two ends in the Y direction of the third refrigerant passage 730. However, as described above, the multiple heat dissipation fins 738 are located on the center side in the Y direction of the third refrigerant passage 730. In contrast, nothing is provided on the two ends in the Y direction of the third refrigerant passage 730. These two ends form gaps extending in the X direction.

[0099] Therefore, the flow resistance is higher at the center than at the ends of the third refrigerant passage 730. As indicated by the thickness and length of the solid arrows, the flow velocity of the refrigerant flowing in the X direction through the third refrigerant passage 730 tends to be faster at the ends than at the center.

[0100] The refrigerant flowing in the X direction from the third left surface 731 to the third right surface 732 along the center side of the third refrigerant passage 730 in the Y direction flows down into the third communication hole 753 with its flow direction being disturbed by the heat dissipation fins 738. The heat dissipation fins 738 may be aligned in the Z direction with the region of the third communication hole 753 on the third left surface 731 side.

[0101] In contrast, a portion of the refrigerant flowing in the X direction from the third left surface 731 to the third right surface 732 at the end of the third refrigerant passage 730 on the third front surface 733 side in the Y direction flows through the gap in the Y direction between the third communication hole 753 and the third front surface 733. A portion of the refrigerant flowing in the X direction from the third left surface 731 to the third right surface 732 at the end of the third refrigerant passage 730 on the third rear surface 734 side in the Y direction flows through the gap in the Y direction between the third communication hole 753 and the third rear surface 734.

[0102] The refrigerant that has flowed through these two gaps in the Y direction flows into a gap that extends in the Y direction between the third communication hole 753 and the third right surface 732 and connects to the gap extending in the X direction described above. The refrigerant then changes its flow direction due to the third right surface 732. The refrigerant flows in the X direction from the third right surface 732 to the third left surface 731. The refrigerant having this X-direction component flows down into the third communication hole 753.

[0103] In the present embodiment, an example has been shown in which gaps are formed both between the third communication hole 753 and the third front surface 733 in the Y direction and between the third communication hole 753 and the third rear surface 734. However, a configuration in which only one of these two gaps is formed may also be employed.

[0104] In this embodiment, the heat dissipation fins 738 are located at the center of the third refrigerant passage 730 in the Y direction, not at the ends. However, the heat dissipation fins 738 may be located not only at the center of the third refrigerant passage 730 but also at the ends. The heat dissipation fins 738 may be located on at least one of the third front surface 733 side and the third rear surface 734 side. In this case, however, the distribution density of the heat dissipation fins 738 in the Y direction will be higher at the center than at the ends.

[0105] In this embodiment, an example has been shown in which the flow resistance is higher at the center of the third refrigerant passage 730 in the Y direction than at the ends thereof by devising a distribution of the heat dissipation fins 738. However, the flow resistance may be changed between the center and ends of the third refrigerant passage 730 by placing something that has high flow resistance in a specific area, other than the heat dissipation fins 738, or by changing the shape of the third refrigerant passage 730 itself. The configuration for achieving high and low flow resistance is not particularly limited.

[0106] 6 , the opening shape of the third communication hole 753 is rectangular. This opening is longer in the Y direction than in the X direction. Therefore, refrigerant flowing in the X direction can flow more easily into the third communication hole 753 than refrigerant flowing in the Y direction.

[0107] As shown in FIG. 4 , the length of the third communication hole 753 in the Z direction is shorter than the length in the X direction. As described above, the length of the third communication hole 753 in the X direction is shorter than the length in the Y direction. Therefore, the length of the third communication hole 753 in the Z direction is shorter than the lengths in the X and Y directions. In this embodiment, as shown in FIG. 4 , the length of the third communication hole 753 in the Z direction is shorter than the length of the second communication hole 752 in the Z direction. Note that the length of the third communication hole 753 in the Z direction may be shorter than the length in the Y direction but longer than the length in the X direction.

[0108] As described above, the length of the third communication hole 753 in the Z direction is short. Therefore, the flow direction of the refrigerant flowing down the third communication hole 753 is less likely to be corrected by the wall surface that constitutes the third communication hole 753.

[0109] The refrigerant flowing in the X direction from the third right surface 732 to the third left surface 731 flows down from the third communication hole 753 to the fourth refrigerant passage 740. The refrigerant flowing in the X direction and the Z direction flows into the fourth refrigerant passage 740.

[0110] The wall surfaces defining the third communication hole 753 may be inclined with respect to the Z direction so that refrigerant flowing in the X direction and the Z direction can easily flow into the fourth refrigerant passage 740. For example, the X-direction separation distance between two of the annular wall surfaces defining the third communication hole 753 and spaced apart in the X direction may gradually increase as the distance approaches in the Z direction from the third refrigerant passage 730 to the fourth refrigerant passage 740. The two wall surfaces spaced apart in the X direction may be inclined such that the X-direction separation distance from the third right surface 732 gradually increases as the distance approaches in the Z direction from the third refrigerant passage 730 to the fourth refrigerant passage 740.

[0111] <Fourth Refrigerant Passage> As described above, fourth refrigerant passage 740 is defined by second lower surface 620b of second case 620 and first upper surface 610a of first case 610. In the following, to simplify the description of fourth refrigerant passage 740, the wall surfaces defining fourth refrigerant passage 740 will be divided into six surfaces. As shown in Figures 7 to 9 , the wall surfaces defining fourth refrigerant passage 740 are divided into a fourth left surface 741 and a fourth right surface 742 that are spaced apart from each other in the X direction, a fourth front surface 743 and a fourth rear surface 744 that are spaced apart from each other in the Y direction, and a fourth top surface 745 and a fourth bottom surface 746 that are spaced apart from each other in the Z direction.

[0112] The fourth left surface 741 is located closer to the second refrigerant passage 720 in the X direction than the fourth right surface 742. The fourth front surface 743 is located closer to the first refrigerant passage 710 in the Y direction than the fourth rear surface 744. The fourth top surface 745 is located higher than the fourth bottom surface 746 in the Z direction.

[0113] The fourth left surface 741, the fourth rear surface 744, the fourth right surface 742, and the fourth front surface 743 are connected in this order to form a fourth annular surface 747. An opening located on the upper side of the fourth annular surface 747 in the Z direction is closed by a fourth top surface 745, and an opening located on the lower side of the fourth annular surface 747 in the Z direction is closed by a fourth bottom surface 746.

[0114] The fourth refrigerant passage 740 corresponds to the cooling flow path. The fourth left surface 741 corresponds to the first side surface. The fourth right surface 742 corresponds to the second side surface. The fourth front surface 743 corresponds to the third side surface. The fourth rear surface 744 corresponds to the fourth side surface. The fourth top surface 745 corresponds to the top surface. The fourth bottom surface 746 corresponds to the bottom surface. The fourth annular surface 747 corresponds to the annular surface.

[0115] As shown in Figures 8 and 9, the fourth left surface 741 and the fourth right surface 742 extend in the Y direction. These two surfaces are aligned along a plane perpendicular to the X direction. In contrast, the fourth front surface 743 and the fourth rear surface 744 extend in the X direction. The fourth front surface 743 has a curved shape that is recessed so as to extend away from the fourth rear surface 744 in the Y direction. The fourth rear surface 744 also has a curved shape that is recessed so as to extend away from the fourth front surface 743 in the Y direction.

[0116] A third communication hole 753 opens in the fourth top surface 745. The third communication hole 753 is located closer to the fourth right surface 742 than the fourth left surface 741 in the X direction. The third communication hole 753 is located closer to the fourth front surface 743 than the fourth rear surface 744 in the Y direction. The third communication hole 753 corresponds to a first inlet.

[0117] The discharge pipe 702 opens into the fourth bottom surface 746. The discharge pipe 702 is located closer to the fourth left surface 741 than the fourth right surface 742 in the X direction. The discharge pipe 702 is located closer to the fourth rear surface 744 than the fourth front surface 743 in the Y direction. The discharge pipe 702 corresponds to a second inlet.

[0118] In this way, the third communication hole 753 and the discharge pipe 702 are spaced apart in the X direction and also in the Y direction. In the X direction, the third communication hole 753 is located closer to the fourth right surface 742 than the discharge pipe 702. In the Y direction, the discharge pipe 702 is located closer to the fourth rear surface 744 than the third communication hole 753. The positions of the third communication hole 753 and the discharge pipe 702 in the X direction do not match, and their positions in the Y direction do not match either. Note that the position of a portion of the third communication hole 753 in the Y direction may match the position of a portion of the discharge pipe 702 in the Y direction.

[0119] The opening shape of the third communication hole 753 is different from the opening shape of the discharge pipe 702. The opening shape of the third communication hole 753 is rectangular, while the opening shape of the discharge pipe 702 is circular.

[0120] The third communication hole 753 is longer in the Y direction than in the X direction. The third communication hole 753 has a larger opening area than the discharge pipe 702.

[0121] As described above, the refrigerant flowing in the X direction from the third right surface 732 to the third left surface 731 flows into the third communication hole 753. That is, as shown by the white arrows in FIG. 8 , the refrigerant flowing in the X direction from the fourth right surface 742 to the fourth left surface 741 flows into the third communication hole 753. This refrigerant falls toward the fourth bottom surface 746 in the Z direction and flows toward the fourth left surface 741 in the X direction. When the refrigerant collides with the fourth left surface 741, its flow direction is reversed. The refrigerant flows from the fourth left surface 741 to the fourth right surface 742 in the X direction.

[0122] As described above, the discharge pipe 702, which is the destination of the refrigerant, is separated in the Y direction from the third communication hole 753. Therefore, as described above, the refrigerant falls in the Z direction due to gravity, and the refrigerant changes its flow direction from the X direction between the fourth right surface 742 and the fourth left surface 741 and flows in the Y direction toward the discharge pipe 702. Therefore, the refrigerant flows in a vortex.

[0123] The refrigerant that has flowed toward fourth rear surface 744 where discharge pipe 702 is located flows along the curved shape of fourth rear surface 744. As indicated by the solid arrows in Figure 8, the refrigerant flows in a vortex shape within fourth refrigerant passage 740. The refrigerant then finally flows into discharge pipe 702.

[0124] The refrigerant flows through the fourth refrigerant passage 740, and a part of the refrigerant also flows on the side of the fourth front face 743. This refrigerant flows along the curved shape of the fourth front face 743.

[0125] <Operation and Effect> Refrigerant flowing in the X direction from the fourth right surface 742 to the fourth left surface 741 flows into the fourth refrigerant passage 740 through the third communication hole 753. In the fourth refrigerant passage 740, the third communication hole 753 is located closer to the fourth right surface 742 than the discharge pipe 702. The discharge pipe 702 is located closer to the fourth rear surface 744 than the third communication hole 753. The third communication hole 753 and the discharge pipe 702 are spaced apart in the X direction and also in the Y direction.

[0126] As a result, the refrigerant that flows into the fourth refrigerant passage 740 from the third communication hole 753 tends to flow toward the fourth left surface 741 in the X direction. The refrigerant also tends to flow toward the discharge pipe 702, which is located closer to the fourth rear surface 744 than the third communication hole 753, in the Y direction. As a result, the refrigerant tends to swirl in the fourth refrigerant passage 740 before flowing down from the third communication hole 753 to the discharge pipe 702 in the Z direction. This tends to increase the flow rate of the refrigerant in the fourth refrigerant passage 740.

[0127] The third communication hole 753 is longer in the Y direction than in the X direction. This allows refrigerant with a flow direction in the X direction to easily flow into the third communication hole 753. The refrigerant flowing from the fourth right surface 742 toward the fourth left surface 741 in the X direction easily flows from the third communication hole 753 toward the fourth left surface 741.

[0128] The fourth rear surface 744 has a curved shape that is recessed in the Y direction so as to move away from the fourth front surface 743. This makes it easier for the refrigerant to flow along the curved shape of the fourth rear surface 744. The refrigerant is more likely to swirl within the fourth refrigerant passage 740.

[0129] The opening area of ​​the discharge pipe 702 is smaller than that of the third communication hole 753. This makes it easier for the flow rate of the refrigerant passing through the discharge pipe 702 to be greater than the flow rate of the refrigerant passing through the third communication hole 753. In other words, the flow rate of the refrigerant in the fourth refrigerant passage 740 is easier to increase.

[0130] The fourth front surface 743 has a curved shape that is recessed in the Y direction so as to move away from the fourth rear surface 744. This makes it easier for the refrigerant to flow along the curved shape of the fourth front surface 743. As a result, the refrigerant is more likely to swirl within the fourth refrigerant passage 740.

[0131] A plurality of heat dissipation fins 738 are located toward the center in the Y direction between the third front surface 733 and the third rear surface 734. The two ends of the third refrigerant passage 730 in the Y direction form gaps extending in the X direction. A gap extending in the Y direction is formed between the third communication hole 753 and the third right surface 732.

[0132] Therefore, the flow direction of the refrigerant flowing from the third left surface 731 to the third right surface 732 in the X direction along the center side of the third refrigerant passage 730 in the Y direction is disturbed by the heat dissipation fins 738. This randomly flowing refrigerant flows down into the third communication hole 753. However, refrigerant flowing through the gap at the end side of the third refrigerant passage 730 from the third left surface 731 to the third right surface 732 in the X direction flows into the gap between the third communication hole 753 and the third right surface 732. This refrigerant then changes its flow direction due to the third right surface 732. Refrigerant flowing from the third right surface 732 to the third left surface 731 in the X direction flows down into the third communication hole 753. As a result, refrigerant flowing from the third right surface 732 to the third left surface 731 in the X direction flows down into the third communication hole 753.

[0133] Some of the multiple heat dissipation fins 738 are aligned in the Z direction with the second communication holes 752. This makes it easier to suppress a temperature rise in the third case 630 in which the heat dissipation fins 738 are provided. As a result, it is easier to suppress a temperature rise in the switch case 543 provided in the third case 630.

[0134] The third communication hole 753 is longer in the Y direction than in the X direction.

[0135] This allows refrigerant with a flow direction in the X direction to easily flow into the third communication hole 753. In other words, refrigerant with a flow direction in the X direction from the third right surface 732 to the third left surface 731 easily flows into the third communication hole 753.

[0136] The length of the third communication hole 753 in the Z direction is shorter than the length in the X direction and the length in the Y direction.

[0137] This prevents the wall surfaces that define the third communication hole 753 from correcting the flow direction of the refrigerant flowing through the third communication hole 753. The refrigerant is more likely to flow down from the third communication hole 753 to the fourth refrigerant passage 740 in the flow direction from the third right surface 732 to the third left surface 731 in the X direction. That is, the refrigerant is more likely to flow down from the third communication hole 753 to the fourth refrigerant passage 740 in the flow direction from the fourth right surface 742 to the fourth left surface 741 in the X direction.

[0138] The opening shape of the second communication hole 752 is defined by a left edge 752a and a right edge 752b that are spaced apart in the X direction, and a rear edge 752d and a front edge 752c that are spaced apart in the Y direction. The right edge 752b is inclined so that the distance between it and the left edge 752a in the X direction gradually increases from the rear edge 752d to the front edge 752c in the Y direction.

[0139] Therefore, the refrigerant that flows up from the second communication hole 752 to the third refrigerant passage 730 flows more in the X direction than in the Y direction. This refrigerant is more likely to flow in the X direction along which the third refrigerant passage 730 extends.

[0140] Furthermore, the front edge portion 752c is located closer to the first refrigerant passage 710 in the Y direction than the rear edge portion 752d. That is, the front edge portion 752c is located closer to the condenser case 521 in the Y direction than the rear edge portion 752d.

[0141] The refrigerant that flows from the second communication hole 752 into the third refrigerant passage 730 is more likely to flow toward the front edge 752c in the Y direction than toward the rear edge 752d. The flow rate of the refrigerant flowing toward the front edge 752c is more likely to be faster than that toward the rear edge 752d. Therefore, the refrigerant flowing through the third refrigerant passage 730 is more likely to suppress a temperature rise in the condenser case 521 located on the front edge 752c side.

[0142] Second Embodiment In this embodiment, differences from the first embodiment will be mainly described. Hereinafter, other embodiments will also be described, focusing on differences from the previously described embodiment. Configurations, actions, and effects that are not particularly described in other embodiments are the same as those in the previously described embodiment.

[0143] 10 and 11 , the fourth front surface 743 side of the fourth bottom surface 746 is inclined such that the distance from the third communication hole 753 in the Z direction gradually increases as the distance moves from the fourth front surface 743 toward the fourth rear surface 744 in the Y direction. In other words, the fourth front surface 743 side of the fourth bottom surface 746 is inclined such that the distance from the third communication hole 753 in the Z direction gradually decreases as the distance moves from the fourth rear surface 744 toward the fourth front surface 743 in the Y direction. The fourth front surface 743 side of the fourth bottom surface 746 is inclined such that the distance from the third communication hole 753 in the Z direction gradually decreases as the distance moves from the center between the fourth front surface 743 and the fourth rear surface 744 toward the fourth front surface 743 in the Y direction. In FIG. 11 , the inclined portions of the fourth bottom surface 746 are hatched. The third communication hole 753 is aligned in the Z direction with the inclined portion of the fourth bottom surface 746 .

[0144] This allows the refrigerant to easily flow from the fourth front surface 743 side where the third communication hole 753 is located to the fourth rear surface 744 side where the discharge pipe 702 is located.

[0145] <Other Modifications> The disclosure of this specification is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and elements shown in the embodiments, and can be implemented in various modifications. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses embodiments in which parts and elements of the embodiments are omitted. The disclosure encompasses the substitution or combination of parts and elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0146] In the present embodiment, an example has been shown in which the power conversion device 300 is employed in the in-vehicle system 100 of an electric vehicle. However, the use of the power conversion device 300 is not limited to the above example. The power conversion device 300 can be appropriately employed in hybrid automobiles, trucks, drones, robots, home appliances, and the like.

[0147] In the present embodiment, the case 600 is shown as both housing and cooling the power conversion circuit 500. However, the two functions of housing and cooling may be separated. That is, the case 600 may simply house the power conversion circuit 500. A component separate from the case 600 may be configured as a cooler having a refrigerant passage 700 for cooling the power conversion circuit 500.

[0148] <Disclosure of Technical Ideas> This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, where the subsequent clause alternatively refers to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, where the subsequent clause refers to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0149] <Technical Idea 1> A cooler for cooling a power conversion circuit (500), comprising: an upper surface (745) having an opening for a first inlet (753) through which a refrigerant flows; a lower surface (746) located vertically lower than the first inlet and having an opening for a second inlet (702) through which the refrigerant that has flowed into the first inlet flows; and an annular surface (747) connecting the upper surface and the lower surface; wherein the annular surface has a first side surface (741) and a second side surface (742) that are spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side surface (743) and a fourth side surface (744) that are spaced apart in a vertical direction perpendicular to the vertical direction and the horizontal direction, and the first side surface, the fourth side surface, the second side surface, and the third side surface are connected in order around the vertical direction to form an annular shape; The cooler, wherein the refrigerant flows into the first inlet from the second side surface toward the first side surface in the horizontal direction, the first inlet is located closer to the second side surface in the horizontal direction than the second inlet, and the second inlet is located closer to the fourth side surface in the vertical direction than the first inlet. <Technical Idea 2> The cooler according to Technical Idea 1, wherein the first inlet is longer in the vertical direction than in the horizontal direction. <Technical Idea 3> The cooler according to Technical Idea 1 or Technical Idea 2, wherein the fourth side surface has a curved shape that is recessed so as to move away from the third side surface in the vertical direction. <Technical Idea 4> The cooler according to any one of Technical Ideas 1 to 3, wherein the second inlet has a smaller opening area than the first inlet. <Technical Idea 5> The cooler according to any one of Technical Ideas 1 to 4, wherein the third side surface side of the lower surface is inclined so that the distance from the first inlet in the vertical direction gradually increases as the distance increases from the third side surface toward the fourth side surface in the vertical direction. <Technical Idea 6> The cooler according to any one of Technical Ideas 1 to 5, wherein the third side surface has a curved shape that is recessed so as to move away from the fourth side surface in the vertical direction. <Technical Idea 7> The cooler according to any one of Technical Ideas 1 to 6, which cools and houses the power conversion circuit.<Technical Idea 8> In addition to the cooling flow path, the refrigerant cooling device has an inflow flow path (730) located above the cooling flow path in the vertical direction, and a plurality of heat dissipation fins (738) provided in the inflow flow path, wherein the inflow flow path is partitioned by a left surface (731) and a right surface (732) spaced apart in the horizontal direction, a front surface (733) and a rear surface (734) spaced apart in the vertical direction, and a top surface (735) and a bottom surface (736) spaced apart in the vertical direction, and the left surface, the rear surface, the right surface, and the front surface are connected in this order around the vertical direction to form an annular partition surface (737), of which two openings the opening located above in the vertical direction is closed by the top surface, and the remaining opening is closed by the bottom surface, the first inflow port opens on the right surface side of the bottom surface, and an upstream port (752) through which the refrigerant flows opens on the left surface side of the bottom surface, The cooler according to any one of Technical Ideas 1 to 7, wherein a plurality of the heat dissipation fins are provided between the first inlet and the upstream port in the horizontal direction, a distribution density of the plurality of heat dissipation fins in the vertical direction is higher at a center side between the front surface and the rear surface than at an end side, a gap is provided between the first inlet and the front surface and / or between the first inlet and the rear surface in the vertical direction, and a gap is provided between the first inlet and the right surface in the horizontal direction. <Technical Idea 9> The cooler according to Technical Idea 8, wherein the plurality of heat dissipation fins are arranged at a distance from each other in a direction perpendicular to the vertical direction, and a distance between the plurality of heat dissipation fins and the front surface and a distance between the plurality of heat dissipation fins and the rear surface are longer than a distance between two adjacently arranged heat dissipation fins among the plurality of heat dissipation fins. <Technical Idea 10> The cooler according to Technical Idea 8 or Technical Idea 9, wherein the length of the first inlet in the longitudinal direction is longer than the length of the first inlet in the lateral direction, and the length of the first inlet in the vertical direction is shorter than the length of the first inlet in the longitudinal direction. <Technical Idea 11> The cooler according to any one of Technical Ideas 8 to 10, wherein some of the plurality of heat dissipation fins are aligned with the upstream port in the vertical direction.<Technical Idea 12> A power conversion device having a power conversion circuit (500) and a cooler (600) that cools the power conversion circuit, wherein the cooler has a cooling flow path (740) defined by an upper surface (745) having a first inlet (753) through which a refrigerant flows, a lower surface (746) that is located vertically below the first inlet and has a second inlet (702) through which the refrigerant that has flowed into the first inlet flows, and an annular surface (747) that connects the upper surface and the lower surface, The annular surface has a first side (741) and a second side (742) that are spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side (743) and a fourth side (744) that are spaced apart in a vertical direction perpendicular to the vertical and horizontal directions, and is formed into a ring by connecting the first side, the fourth side, the second side, and the third side in order around the vertical direction, and the refrigerant flows into the first inlet from the second side toward the first side in the horizontal direction, and the first inlet is located closer to the second side in the horizontal direction than the second inlet, and the second inlet is located closer to the fourth side in the vertical direction than the first inlet.

Claims

1. A cooler for cooling a power conversion circuit (500), comprising: an upper surface (745) having an opening for a first inlet (753) through which a refrigerant flows; a lower surface (746) located vertically below the first inlet and having an opening for a second inlet (702) through which the refrigerant that has flowed into the first inlet flows; and an annular surface (747) connecting the upper surface and the lower surface; wherein the annular surface has a first side surface (741) and a second side surface (742) spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side surface (743) and a fourth side surface (744) spaced apart in a vertical direction perpendicular to the vertical direction and the horizontal direction, and the first side surface, the fourth side surface, the second side surface, and the third side surface are connected in order around the vertical direction to form an annular shape; The refrigerant flows into the first inlet from the second side surface toward the first side surface in the horizontal direction, the first inlet is located closer to the second side surface in the horizontal direction than the second inlet, and the second inlet is located closer to the fourth side surface in the vertical direction than the first inlet.

2. The cooler according to claim 1, wherein the first inlet is longer in the vertical direction than in the horizontal direction.

3. A cooler according to claim 1 or claim 2, wherein the fourth side surface has a curved shape that is recessed so as to move away from the third side surface in the vertical direction.

4. A cooler according to claim 1 or claim 2, wherein the second inlet has an opening area smaller than that of the first inlet.

5. A cooler as described in claim 1 or claim 2, wherein the third side surface of the lower surface is inclined so that the distance from the first inlet in the vertical direction gradually increases as the distance moves from the third side surface to the fourth side surface in the longitudinal direction.

6. A cooler according to claim 1 or claim 2, wherein the third side surface has a curved shape that is concave so as to move away from the fourth side surface in the vertical direction.

7. A cooler according to claim 1 or 2, which cools and houses the power conversion circuit.

8. In addition to the cooling flow path, the cooling device has an inlet flow path (730) located above the cooling flow path in the vertical direction, and a plurality of heat dissipation fins (738) provided in the inlet flow path, wherein the inlet flow path is partitioned by a left surface (731) and a right surface (732) spaced apart in the horizontal direction, a front surface (733) and a rear surface (734) spaced apart in the vertical direction, and a top surface (735) and a bottom surface (736) spaced apart in the vertical direction, and the left surface, the rear surface, the right surface, and the front surface are connected in this order around the vertical direction to form an annular partition surface (737), of which two openings the opening located above in the vertical direction is closed by the top surface, and the remaining opening is closed by the bottom surface, wherein the first inlet opens on the right surface side of the bottom surface, and an upstream opening (752) through which the refrigerant flows opens on the left surface side of the bottom surface, The cooler of claim 1, wherein a plurality of the heat dissipation fins are provided between the first inlet and the upstream port in the horizontal direction, the distribution density of the plurality of heat dissipation fins in the vertical direction is higher at the center between the front surface and the rear surface than at the ends, a gap is formed between the first inlet and the front surface in the vertical direction and / or between the first inlet and the rear surface, and a gap is formed between the first inlet and the right surface in the horizontal direction.

9. A cooler as described in claim 8, wherein the plurality of heat dissipation fins are arranged at intervals in a direction perpendicular to the vertical direction, and the distance between the plurality of heat dissipation fins and the front surface and the distance between the plurality of heat dissipation fins and the rear surface are longer than the distance between any two of the plurality of heat dissipation fins that are arranged adjacent to each other.

10. A cooler as described in claim 8, wherein the length of the first inlet in the vertical direction is longer than the length of the first inlet in the horizontal direction, and the length of the first inlet in the vertical direction is shorter than the length of the first inlet in the vertical direction.

11. The cooler according to claim 8, wherein a portion of the plurality of heat dissipating fins are aligned vertically with the upstream opening.

12. A power conversion device having a power conversion circuit (500) and a cooler (600) for cooling the power conversion circuit, wherein the cooler has a cooling flow path (740) defined by an upper surface (745) having a first inlet (753) through which a refrigerant flows, a lower surface (746) located vertically below the first inlet and having a second inlet (702) through which the refrigerant that has flowed into the first inlet flows, and an annular surface (747) connecting the upper surface and the lower surface; The annular surface has a first side (741) and a second side (742) that are spaced apart in a horizontal direction perpendicular to the vertical direction, and a third side (743) and a fourth side (744) that are spaced apart in a vertical direction perpendicular to the vertical and horizontal directions, and is formed into a ring by connecting the first side, the fourth side, the second side, and the third side in order around the vertical direction, and the refrigerant flows into the first inlet from the second side toward the first side in the horizontal direction, and the first inlet is located closer to the second side in the horizontal direction than the second inlet, and the second inlet is located closer to the fourth side in the vertical direction than the first inlet.

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