JP2014087245A - Power control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which uses a structure peculiar to a power control unit for supplying a motor for travelling with power to inexpensively produce a pressure control part that reduces pressure difference between an inside and an outside of a case.SOLUTION: In a power control unit 10, a case 12 is provided with an opening 13 for exposing a terminal connecting a cable 3 that supplies a motor with power. A cover (cap 7) for closing the opening is provided with a pressure control part. The pressure control part is typically an air hole 7a provided with a ventilation film 8 that passes gas but not fluid. There are a plurality of cables which supply the motor with power, and each one of them is thick. The opening 13 connecting such cables are equivalently large. Since the opening part cover has an equivalent area, it is very convenient to provide the pressure control part. Normally, the opening cover is made of resin, so that manufacturing is easier when installing the control pressure part in the opening cover made of resin and requires lower costs than when installing the same in a metal case.

Description

  The present invention relates to a power control unit that is mounted on an electric vehicle and supplies electric power to a motor for traveling. The electric vehicle in this specification includes a fuel cell vehicle and a hybrid vehicle including both a motor and an engine for traveling.

  An electronic device mounted in an engine compartment of an electric vehicle is sealed in a case for waterproofing. However, if only sealed, the internal pressure of the case changes according to a change in atmospheric pressure (for example, when driving to a place with a high altitude), and the change in internal pressure may cause deterioration of the sealing member that seals the case. In view of this, for example, Patent Document 1 proposes that a case of an electronic device is provided with a pressure adjusting unit that reduces a pressure difference inside and outside the case. Specifically, the pressure adjusting unit is a vent hole provided with a gas permeable membrane that allows passage of gas and blocks passage of liquid. Even for an electric vehicle not equipped with an engine, for convenience of explanation, a space for accommodating a drive system device such as a motor is referred to as an “engine compartment”.

JP 2006-135250 A

  In many cases, the case of an electronic device is made of metal, and it is costly to provide a pressure adjusting unit (typically, a vent hole having a gas permeable membrane) in the metal case. The present specification provides a technology that uses a structure unique to a power control unit that supplies power to a motor for traveling, and realizes a pressure adjustment unit that reduces a pressure difference between the inside and outside of the case at a low cost.

  The power control unit includes an opening in the case for exposing a connection terminal in order to connect a cable for supplying power to the motor. Since a cable for supplying electric power to the motor is called a “power cable”, in the present specification, such a cable may be referred to as a “power cable” hereinafter.

  On the other hand, a cover is attached to the opening. In the technology disclosed in this specification, a pressure adjusting unit that reduces the pressure difference between the inside and outside of the power control unit is provided in the cover (opening cover). As described above, the pressure adjusting unit may typically be a vent hole including a vent film that allows gas to pass but not liquid to pass. Since power is supplied to the motor for traveling, the power cable is relatively thick. Furthermore, in an electric vehicle equipped with a three-phase AC motor for traveling, three power cables are required, and the opening for connecting the power cable is also suitable. Will have a size of Therefore, since the opening cover has a corresponding area, it is convenient to provide the pressure adjusting portion. Since the opening cover is usually made of resin, it is easier to manufacture and can be realized at a lower cost if the pressure adjusting portion is provided in the resin opening cover than providing the pressure adjusting portion in the metal case.

  The opening cover must seal the opening. Therefore, the opening cover is preferably composed of a resin frame fixed around the opening with a face seal and a resin cap fitted into the frame with a shaft seal. The cover is composed of a frame and a cap. The frame is in close contact with the housing with a face seal, and the cap is in close contact with the frame with a shaft seal. By adopting such a structure, it is possible to easily replace only the cap provided with the pressure adjusting unit.

  The cap has a U-shaped cross section, and it is preferable that a gap is secured between the bolt for fixing the cable to the terminal in the opening and the pressure adjusting unit. By providing a space also inside the pressure adjusting unit (inside the casing of the power control unit), air can easily flow and the ventilation effect is increased. In addition, a cross section here means the cross section in the surface orthogonal to the plane containing an opening part.

  In the case where the pressure adjusting unit is a vent hole provided with a gas permeable membrane that allows gas to pass but not liquid, the gas permeable membrane is not high in strength. Therefore, it is preferable that the power control unit disclosed in the present specification further includes a metal overcover that covers the pressure adjusting portion (vent hole) with a gap. The metal overcover protects the gas permeable membrane, and a clearance is provided between the overcover and the air vent to ensure an air flow path. The metal overcover also serves as a shield shell that blocks external electromagnetic noise from the terminals in the opening.

  Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a perspective view which shows the external appearance of a power control unit. It is a disassembled perspective view of an opening part periphery. FIG. 3 is an exploded view in a section taken along line III-III in FIG. 1. It is sectional drawing of the III-III line arrow of FIG.

  A power control unit 10 according to an embodiment will be described with reference to the drawings. For simplification, the power control unit (Power Control Unit) 10 is simply referred to as PCU 10 below. The PCU 10 is a device that is mounted on an electric vehicle and converts battery power into alternating current and outputs the alternating current to a motor for traveling. The PCU 10 includes a booster circuit that boosts the voltage of the battery, and an inverter circuit that converts the boosted direct current into alternating current. Description of the configuration of the booster circuit and the inverter circuit is omitted.

  FIG. 1 shows an external view of the PCU 10. The PCU 10 is mounted immediately above the drive train 20 that houses a motor for traveling (not shown). The PCU 10 according to the embodiment is fixed by a bracket 21 with a gap 22 immediately above the drive train 20. The PCU 10 and the motor are electrically connected by a power cable 3 (see FIG. 2) that supplies electric power. The electric vehicle of the embodiment has two driving three-phase AC motors mounted in the drive train 20, and from the PCU 10, three sets of UVW three phases and one set of power cables are extended to a total of six sets. Yes. The power cable 3 is connected to the drive train 20 directly below the PCU 10, passes through a gap 22 immediately below the PCU 10, and is connected to a terminal on the PCU side through an opening 13 provided in the side surface 12 a of the casing 12 of the PCU 10. The The housing 12 is made of metal (typically aluminum). In FIG. 1, the opening 13 is covered with the shield shell 9.

  FIG. 2 shows an exploded perspective view around the opening 13. FIG. 3 shows an exploded view taken along the line III-III in FIG. In FIG. 2, it should be noted that the power cable 3 is divided on the way to help understanding. In FIG. 3, illustration of the power cable 3 from the middle (motor side) is omitted.

  Six PCU side terminals 14 can be seen through the opening 13. In other words, six PCU side terminals 14 are exposed through the opening 13. As described above, one end of the power cable 3 is connected to the drive train 20 immediately below the PCU 2, and the other end is connected to the PCU side terminal 14 through the opening 13. Since the drive train 20 is equipped with two UVW three-phase AC motors, the number of power cables is six (3 UVWs × 2 sets). Since the traveling motor has a large output of several tens of kilowatts, each power cable is thick, and since there are six power cables, the opening 13 has a corresponding size.

  The six cable side terminals 2 are supported by the terminal holder 4 so that each one does not fall apart. In FIG. 2, the terminal holder 4 and the frame body 6 are depicted as separate parts, but this is for the purpose of facilitating understanding. In fact, the terminal holder 4 and the frame body 6 are integrated. The terminal holder 4 and the frame 6 are integrally formed by resin injection molding. The upper surface 4b of the terminal holder 4 is joined to the notch 6c of the frame body 6 (see FIGS. 2 and 3). Hereinafter, a combination of the terminal holder 4 and the frame 6 is referred to as a connector frame 5.

  The connector frame 5 is fixed to the side surface 12 a of the housing 12 of the PCU 10 with bolts 32. Although not shown in FIG. 2, as shown in FIG. 3, the connector frame 5 is a casing of the PCU 2 with a planar sealing material (face seal 46) sandwiched around the opening 13. Twelve side surfaces 12 a are fixed with bolts 32. More specifically, the bottom surface of the connector frame 5 (the bottom surface 6a of the frame body 6 and the bottom surface 4a of the terminal holder 4) faces the side surface 12a of the housing 12, and the connector frame is sandwiched between them with a surface seal 46 interposed therebetween. 5 is fixed to the side surface 12a with four bolts 32. The connector frame 5 is cylindrical and has a hollow inside. Therefore, after the connector frame 5 including the terminal holder 4 is fixed to the housing 12, the bolt 31 is passed inside the cylinder, and the PCU side terminal 14 and the cable side terminal 2 are fastened and connected to each other. Although only one bolt 31 is illustrated in FIG. 2, the six PCU side terminals 14 and the six cable side terminals 2 are fixed to each other by the bolts 31.

  After all the PCU side terminals 14 and the cable side terminals 2 are fixed, the cap 7 is fitted to the cylindrical portion to close the opening 13. The cap 7 is made of resin. The cap 7 has a bottomed cylindrical shape, and the outer peripheral surface 7 b of the cylindrical portion is fitted with the inner peripheral surface of the cylindrical portion of the connector frame 5 (the inner peripheral surface 6 b of the frame body 6). The space between the outer peripheral surface 7b of the cylindrical portion and the inner peripheral surface of the cylindrical portion of the connector frame 5 (the inner peripheral surface 6b of the frame body 6) is sealed with an O-ring 47. That is, the cylindrical part of the connector frame 5 and the cap 7 are fitted together with a shaft seal.

  A vent hole 7a is provided substantially at the center of the bottom of the cap 7, and the vent hole 7a is covered with a vent film 8 that allows gas to pass but does not allow liquid to pass. Specifically, for example, Gore-Tex (registered trademark), which is a waterproof and moisture-permeable material, is used for the ventilation film 8. A shield shell 9 that covers both the cap 7 and the connector frame 5 is attached to the outside of the cap 7. The shield shell 9 is fixed to the side surface 12 a of the housing 12 with a bolt 33 so as to cover the connector frame 5. The shield shell 9 is made of metal, protects the air permeable membrane 8, blocks external electromagnetic noise, and prevents electromagnetic noise from being applied to the PCU side terminal 14 and the cable side terminal 2.

  FIG. 4 is a cross-sectional view taken along the line III-III in FIG. As shown in FIG. 4, the shield shell 9 covers the vent hole 7a with a gap Sa therebetween. The cap 7 has a U-shaped cross section (a cross section in a plane that intersects the plane including the opening 13) that opens toward the inside of the PCU 10, and a gap Sb is formed between the bolt 31 and the vent hole 7a. It is secured. That is, gaps Sa and Sb are secured before and after the vent hole 7a. Further, a gap is provided below the shield shell 9 (in the negative direction of the Z axis in the drawing) from the outside to the ventilation hole 7a. As shown by an arrow A in FIG. Gas can permeate through the air holes 7a.

  As described above, the PCU 10 includes the opening 13 that connects the power cable 3 and includes the opening cover (the connector frame 5 and the cap 7) that covers the opening 13. The opening cover (cap 7) is provided with a vent hole 7a, and a vent film 8 that allows gas to pass but not liquid is attached to the vent hole 7a. Since the air inside the PCU 10 can enter and exit through the gas permeable membrane, the internal pressure of the PCU 10 is always kept equal to the external pressure. Therefore, there is no pressure difference between the inside and outside of the PCU 10, and a load due to the pressure difference between the inside and outside is not applied to the seal member (for example, the face seal 46 or the O-ring 47) provided in the PCU 10.

  The gas permeable membrane 8 is made of a material that allows gas to pass through but does not allow liquid to pass through. Water droplets (rainwater, etc.) do not enter the inside of the PCU 10 through the gas permeable membrane 8. Furthermore, since the shield shell 9 covers the upper side of the gas permeable membrane 8, the adhesion of water droplets to the gas permeable membrane 8 is also reduced.

  Moreover, since the space | gap is ensured before and behind the vent hole 7a, air flows smoothly through the vent hole 7a. Further, since the air hole 7a having the air permeable film 8 is covered with a metal cover (shield shell 9), the air permeable film 8 is not broken by hitting anything.

  The vent hole 7 a having the vent film 8 is provided in a resin cover (cap 7) that covers the opening 13 for connecting the power cable 3. There are a plurality of power cables 3 (six in the case of the embodiment), and since each one is thick, the opening 13 has a corresponding area. Accordingly, the opening cover (cap 7) also has a corresponding area. Since the cap 7 has a corresponding area, it is convenient to provide a vent hole. Further, the vent hole 7a can be formed at the same time as the resin cover (cap 7) is formed, so that it can be obtained with little cost.

  Points to be noted regarding the technology described in the embodiments will be described. In the embodiment, the vent hole 7a is circular, but is not limited to circular. Further, the number of vent holes 7a is not limited to one. The vent hole 7a provided with the vent film 8 that allows gas to pass but does not allow liquid to pass is an example of the pressure adjusting unit. The pressure adjusting unit is not limited to the vent hole 7a as long as it can prevent a liquid from entering and at the same time reduce the pressure difference inside and outside the power controller. The cap 7 corresponds to an example of a cover that closes the opening 13. The connector frame 5 may constitute a part of the “cover for closing the opening 13”. The metal shield shell 9 corresponds to an example of an over cover.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Cable side terminal 3: Power cable 4: Terminal holder 5: Connector frame 6: Frame body 7: Cap 7a: Vent (pressure-regulating part)
8: Ventilation membrane 9: Shield shell 10: Power control unit (PCU)
12: Housing 13: Opening 14: PCU side terminal 20: Drive train 21: Brackets 31, 32, 33: Bolt 46: Face seal 47: O-ring

Claims (5)

It is a power control unit that supplies power to the motor for running,
An opening for exposing the terminal that connects the cable that supplies power to the motor is provided in the casing of the power control unit, and the cover that closes the opening reduces the pressure difference inside and outside the power control unit. A power control unit for an electric vehicle, characterized in that a pressure adjusting unit is provided.   2. The power control unit according to claim 1, wherein the pressure adjusting unit is a ventilation hole provided with a ventilation film that allows gas to pass but does not allow liquid to pass.   The said cover is comprised by the resin-made frame fixed to the periphery of the said opening part with a face seal, and the resin-made cap fitted to a frame with a shaft seal. The power control unit according to 1 or 2.   4. The power control unit according to claim 3, wherein the cap has a U-shaped cross section, and a gap is secured between a bolt for fixing the cable to the terminal and a pressure adjusting unit.   The power control unit according to any one of claims 1 to 4, further comprising a metal overcover that covers the pressure adjusting unit with a gap therebetween.

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