JP2007294806A - Cooling structure of electric device, and motor driven vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of an electric device which can suppress generation of a circulating current via an engagement member, and to provide a motor driven vehicle having such a structure. <P>SOLUTION: The cooling structure of an electric device comprises a semiconductor element 95, a heat sink 10 on which the semiconductor element 95 is mounted, a case 20 containing a metal different from the material of the heat sink 10 and joined to the heat sink 10 in such a manner that a coolant passage 30 is defined between the case and the heat sink 10, a bolt 40 which tightens the heat sink 10 and the case 20, and a washer 50 provided between the bolt 40 and the heat sink 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cooling structure for an electric device and an electric vehicle, and more particularly to a cooling structure for an electric device in which a refrigerant passage is formed between different types of metals having different ionization tendencies and an electric vehicle including the structure.

A cooling structure in which a coolant channel is formed inside a metal member is conventionally known.
For example, in Japanese Patent Application Laid-Open No. 2005-221091 (Patent Document 1), in a water-cooled radiator that cools a laser diode array with cooling water that flows through a channel formed inside, It is disclosed to provide a titanium oxide layer that covers the surface and electrically insulates the cooling water from the radiator.

  Japanese Patent Laying-Open No. 2005-302886 (Patent Document 2) discloses a cooling structure in which a coolant chamber is formed between a base plate on which a semiconductor chip is mounted and a heat sink. Here, a rubber member is provided between the base plate and the heat sink.

  Japanese Utility Model Laid-Open No. 64-35794 (Patent Document 3) discloses a cooling structure in which an O-ring is provided on a joint surface between a cooling plate and a flange portion assembled to the plate.

Japanese Laid-Open Patent Publication No. 57-37258 (Patent Document 4) discloses a semiconductor device in which an insulating seat is interposed between a semiconductor element and a water cooling block.
JP 2005-221091 A Japanese Patent Laying-Open No. 2005-302886 Japanese Utility Model Publication No. 64-35794 JP 57-37258 A

  When dissimilar metals having different ionization tendencies are joined together and a refrigerant flow path is formed inside them, a circulating current flowing between the dissimilar metals via the refrigerant is likely to be generated. Such circulating current causes electrolytic corrosion and corrodes the member defining the refrigerant flow path.

  In patent document 1, the protective layer which electrically insulates a cooling water and a heat radiator is formed. However, in this case, it is necessary to provide a protective layer over the entire cooling channel, which complicates the manufacturing process. In Patent Document 2, a rubber member is provided between the base plate and the heat sink. However, since the base plate and the heat sink are connected by screws, a circulating current may be generated via the screws. . A configuration that solves the above problem is not disclosed in Patent Documents 3 and 4.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a cooling structure for an electric device capable of suppressing the generation of a circulating current through a fastening member with a simple configuration, and It is providing the electric vehicle provided with this structure.

  The cooling structure for an electrical device according to the present invention includes an electrical component, a first metal member on which the electrical component is mounted, a metal different from the first metal member, and is joined to the first metal member. At least one of the second metal member constituting the refrigerant passage, the conductive fastening member for fastening the first and second metal members, and the fastening member and the first and second metal members. And an insulating part provided between the two.

  According to the said structure, generation | occurrence | production of the circulating current which flows between 1st and 2nd metal members via a refrigerant | coolant and a fastening member can be suppressed by providing an insulating part.

  In the specification of the present application, “electrical component” includes both an electronic component included in a circuit that performs information processing and a device for generating power and light.

  In the cooling structure for the electric device, preferably, the insulating portion includes a washer for a fastening member. Thereby, generation | occurrence | production of a circulating current can be suppressed with a simple structure. Further, since the washer and the insulating portion can be used together, the generation of circulating current can be suppressed without increasing the number of parts.

  In the cooling structure of the electric device, as one example, at least one of the first and second metal members has an opening through which the fastening member is inserted, and the washer is formed of the first and second metal members. It is provided so as to be located on the wall surface of the hole from at least one main surface.

  In this case, it is possible to suppress the current from the fastening member from flowing through the metallic member through the main surface of the metallic member and the wall surface of the hole. As a result, the generation of the circulating current can be effectively suppressed.

  Preferably, the cooling structure for the electric device further includes another insulating portion provided on the joint surface between the first and second metal members. Thereby, generation | occurrence | production of the circulating current which flows without passing through a fastening member can be suppressed.

  In the cooling structure of the electric device, as another example, the other insulating portion is a seal member that seals the joint portion between the first and second metal members.

  In this case, since the sealing member and the insulating portion can be used together, the generation of circulating current can be suppressed without increasing the number of parts.

  The electric vehicle according to the present invention includes the above-described cooling structure for electric equipment. Thus, an electric vehicle in which corrosion of the metal member that defines the refrigerant passage is suppressed is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the electrolytic corrosion by the circulating current which flows between dissimilar metals can be suppressed.

  Embodiments of the present invention will be described below. Note that the same or corresponding parts are denoted by the same reference numerals, and the description thereof may not be repeated.

  Note that in the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. In the following embodiments, each component is not necessarily essential for the present invention unless otherwise specified. In addition, when there are a plurality of embodiments below, it is planned from the beginning to appropriately combine the features of each embodiment unless otherwise specified.

  FIG. 1 is a diagram showing a hybrid vehicle (HV) including a cooling structure for an electrical device according to an embodiment of the present invention. In the present specification, the “electric vehicle” is not limited to the hybrid vehicle, and for example, a fuel cell vehicle and an electric vehicle are also included in the “electric vehicle”. An engine as an “internal combustion engine” to be described later may be a gasoline engine or a diesel engine. A capacitor may be used instead of the secondary battery described later.

  Referring to FIG. 1, hybrid vehicle 1 includes an engine 100, a motor generator 200, a PCU (Power Control Unit) 300, a battery 400 that is a chargeable / dischargeable secondary battery, a power split mechanism 500, a differential, and the like. It includes a mechanism 600, a drive shaft 700, and drive wheels 800L and 800R that are front wheels.

  As shown in FIG. 1, engine 100, motor generator 200, PCU 300, and power split mechanism 500 are arranged in the engine room. Motor generator 200 and PCU 300 are connected by a cable 300A. PCU 300 and battery 400 are connected by a cable 400A. A power output device including engine 100 and motor generator 200 is connected to differential mechanism 600 through power split mechanism 500. Differential mechanism 600 is coupled to drive wheels 800L and 800R via drive shaft 700.

  Next, the configuration of the motor generator 200 and its periphery will be described in more detail with reference to FIG.

  Referring to FIG. 2, motor generator 200 includes motor generators 210 and 220. Motor generators 210 and 220 are rotating electrical machines having at least one function of an electric motor and a generator. A speed reduction mechanism 550 is provided between the power split mechanism 500 and the differential mechanism 600. Differential mechanism 600 is connected to drive shaft 700 via drive shaft receiving portion 650. Motor generators 210 and 220, power split mechanism 500, reduction mechanism 550 and differential mechanism 600 are provided in casing 900.

  Motor generators 210 and 220 are electrically connected to cables 300A1 and 300A2 via terminal blocks 910 and 920 provided in housing 900, respectively. The other ends of the cables 300A1 and 300A2 are connected to the PCU 300. PCU 300 is electrically connected to battery 400 via cable 400A. Thereby, battery 400 and motor generators 210 and 220 are electrically connected.

  Power split device 500 is constituted by a plurality of planetary gears, for example, and has a power split function and a speed reduction function. Here, the ring gear in the plurality of planetary gears may be constituted by one cylindrical member.

  When the hybrid vehicle travels, the power output from the engine 100 is transmitted to the shaft 150 and divided into two paths by the power split mechanism 500.

  One of the two paths is a path that is transmitted from the speed reduction mechanism 550 to the drive shaft receiving portion 650 via the differential mechanism 600. The driving force transmitted to the drive shaft receiving portion 650 is transmitted as a rotational force to the drive wheels 800L and 800R via the drive shaft 700, thereby causing the vehicle to travel.

  The other is a path for driving the motor generator 210 to generate power. Motor generator 210 generates power using the engine power distributed by power split device 500. The electric power generated by the motor generator 210 is properly used according to the running state of the vehicle and the state of the battery 400. For example, during normal traveling and sudden acceleration of the vehicle, the electric power generated by motor generator 210 is directly used as electric power for driving motor generator 220. On the other hand, under the conditions determined in battery 400, the electric power generated by motor generator 210 is stored in battery 400 through an inverter and a converter provided in PCU 300.

  Motor generator 220 is driven by at least one of the electric power stored in battery 400 and the electric power generated by motor generator 210. The driving force of motor generator 220 is transmitted from reduction mechanism 550 to drive shaft receiving portion 650 via differential mechanism 600. By doing so, the driving force of engine 100 can be assisted by the driving force from motor generator 220, or hybrid vehicle 1 can be driven only by the driving force from motor generator 220.

  On the other hand, during regenerative braking of hybrid vehicle 1, drive wheels 800L and 800R are rotated by the inertial force of the vehicle body. Motor generator 220 is driven through drive shaft receiving portion 650, differential mechanism 600 and reduction mechanism 550 by the rotational force from drive wheels 800 </ b> L and 800 </ b> R. At this time, the motor generator 220 operates as a generator. Thus, motor generator 220 functions as a regenerative brake that converts braking energy into electric power. The electric power generated by the motor generator 220 is stored in the battery 400 via an inverter provided in the PCU 300.

  FIG. 3 is a circuit diagram showing a configuration of a main part of PCU 300. Referring to FIG. 3, PCU 300 includes a converter 310, inverters 320 (321 and 322), a control device 330, and capacitors C1 and C2. Converter 310 is connected between battery 400 and inverter 320, and inverters 321 and 322 are connected to motor generators 210 and 220, respectively.

  Converter 310 includes power transistors Q1 and Q2, diodes D1 and D2, and a reactor L. Power transistors Q1 and Q2 are connected in series and receive a control signal from control device 330 as a base. Diodes D1 and D2 are connected between the collector and emitter of power transistors Q1 and Q2, respectively, so that current flows from the emitter side to the collector side of power transistors Q1 and Q2. Reactor L has one end connected to a power supply line connected to the positive electrode of battery 400, and the other end connected to a connection point between power transistors Q1 and Q2.

Converter 310 uses reactor L to boost the DC voltage received from battery 400 and supplies the boosted voltage to the power supply line. Converter 310 steps down the DC voltage received from inverter 320 and charges battery 400.

  Inverters 321 and 322 include U-phase arms 321U and 322U, V-phase arms 321V and 322V, and W-phase arms 321W and 322W, respectively. U-phase arm 321U, V-phase arm 321V and W-phase arm 321W are connected in parallel between nodes N1 and N2. Similarly, U-phase arm 322U, V-phase arm 322V, and W-phase arm 322W are connected in parallel between nodes N1 and N2.

  U-phase arm 321U includes two NPN transistors Q3 and Q4 connected in series. Similarly, U-phase arm 322U, V-phase arms 321V and 322V, and W-phase arms 321W and 322W each include two NPN transistors Q5 to Q14 connected in series. Further, diodes D3 to D14 for passing a current from the emitter side to the collector side are connected between the collector and emitter of each NPN transistor Q3 to Q14.

  An intermediate point of each phase arm of inverters 321 and 322 is connected to each phase end of each phase coil of motor generators 210 and 220, respectively. In motor generators 210 and 220, one end of three coils of U, V, and W phases is commonly connected to the midpoint.

  Capacitor C1 is connected to battery 400 in parallel. Capacitor C2 is connected in parallel to inverters 321 and 322. Capacitors C1 and C2 smooth the voltage level of the power supply line.

  Inverters 321, 322 drive motor generators 210, 220 by converting the DC voltage from capacitor C2 into an AC voltage based on a drive signal from control device 330.

  Current sensors 340U, 340V, 340W, 350U, 350V, and 350W detect currents flowing through motor generators 210 and 220, respectively, and output the detected currents to control device 330.

  Control device 330 calculates each phase coil voltage of motor generators 210 and 220 based on the motor torque command value, each phase current value of motor generators 210 and 220, and the input voltage of inverters 321 and 322. Based on this, a PWM (Pulse Width Modulation) signal for turning on / off the power transistors Q3 to Q14 is generated and output to the inverters 321 and 322.

  Control device 330 calculates the duty ratio of power transistors Q1 and Q2 for optimizing the input voltage of inverter 320 based on the motor torque command value and the motor rotation speed described above, and power based on the calculation result. A PWM signal for turning on / off the transistors Q1 and Q2 is generated and output to the converter 310.

  Further, control device 330 controls switching operations of power transistors Q <b> 1 to Q <b> 14 in converter 310 and inverter 320 in order to charge battery 400 by converting AC power generated by motor generators 210 and 220 into DC power.

  During the operation of the PCU 300, the electronic components constituting the converter 310 and the inverter 320 generate heat. Therefore, a device for cooling them is necessary.

  FIG. 4 is a cross-sectional view showing a cooling structure included in the PCU 300. Referring to FIG. 4, the cooling structure according to the present embodiment includes heat radiating plate 10, case 20, refrigerant passage 30, bolt 40, washer 50, and gasket 60.

  The heat sink 10 is a metal plate made of copper, for example. A semiconductor element 95 is mounted on the heat sink 10 via solders 70A and 70B, metal plates 80A and 80B, and an insulating plate 90. The semiconductor element 95 corresponds to, for example, the power transistors Q1 to Q14 described with reference to FIG.

  Case 20 is a metal case made of, for example, aluminum. By combining the heat radiating plate 10 and the case 20, a coolant passage 30 through which a coolant for cooling the semiconductor element 95 flows is formed. As the refrigerant, for example, LLC (Long Life Coolant) is used. The heat radiating plate 10 and the case 20 are fastened by bolts 40. Bolt 40 is made of, for example, iron.

  The washer 50 is a “washer” for the bolt 40. The gasket 60 is a “seal member” that seals the joint between the heat sink 10 and the case 20. The washer 50 and the gasket 60 are formed of an insulating material at least on the surface.

  Since the heat radiating plate 10 is a member on which the semiconductor element 95 that is a “heating element” is mounted, it is desired that the heat radiating plate 10 be made of a material having a high heat transfer coefficient in order to perform efficient cooling. . In consideration of thermal contraction when the solder 70A provided on the heat sink 10 is cured, it is desirable to configure the heat sink 10 with a material whose linear expansion coefficient is relatively close to the solder 70A or the like. From such a viewpoint, for example, copper is suitable as a material for the heat sink 10.

  On the other hand, the case 20 is a member larger than the heat radiating plate 10 in the example of FIG. 4 and is not a member on which the semiconductor element 95 that is a “heating element” is directly mounted. In addition, it is desired that the case 20 be made of a material suitable for weight reduction. From such a viewpoint, for example, aluminum is suitable as a material for the case 20.

  As described above, there are cases where it is desired to form the heat sink 10 and the case 20 from different metals. In this case, the ionization tendency of the metal constituting the heat radiating plate 10 is different from the ionization tendency of the metal constituting the case 20. As a result, there is a concern that a circulating current flows between the radiator plate 10 and the case 20 via the refrigerant in the refrigerant passage 30, and electrolytic corrosion occurs in the radiator plate 10 and the case 20. On the other hand, in the cooling structure according to the present embodiment, the generation of the circulating current is suppressed by using the insulating washer 50 and the gasket 60.

  5 is a perspective view showing the washer 50, and FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. Referring to FIGS. 5 and 6, washer 50 has a substantially L-shaped cross-sectional shape, a first portion 51 located on the main surface of heat sink 10, and an opening 10 </ b> A through which bolt 40 is inserted. And a second portion 52 located on the wall surface. The washer 50 is formed by providing an insulating portion 50D (insulating coating) on the surface of a conductive portion 50C made of metal, for example.

  FIG. 7 is a cross-sectional view showing the gasket 60. Referring to FIG. 7, gasket 60 is a metal gasket and is formed by providing insulating portion 60D (insulating coating) on the surface of conductive portion 60C.

  Next, a mechanism for suppressing circulating current through the refrigerant by the washer 50 and the gasket 60 will be described with reference to FIG. Referring to FIG. 8, by providing a washer 50 whose surface is made of an insulating material, an electric loop (arrow A in FIG. 8) that circulates between heat sink 10, bolt 40, and case 20 through the refrigerant is eliminated. be able to. Moreover, by providing the gasket 60 whose surface is made of an insulating material, it is possible to eliminate an electric loop (arrow B in FIG. 8) that circulates between the heat sink 10 and the case 20 via the refrigerant. As a result, the electric corrosion of the heat sink 10 and the case 20 can be prevented.

  Next, a modified example of the cooling structure will be described with reference to FIGS. In the example of FIG. 9, the bolt 40 is inserted into the opening 10 </ b> A provided in the heat radiating plate 10 and the opening 20 </ b> A provided in the case 20. The heat sink 10 and the case 20 are fastened by bolts 40 and nuts 41. The example of FIG. 9 also has the same effect as the effect described in FIG. In the example of FIG. 10, a washer 50A made of a conductive material is used as a washer for the bolt 40, and an insulating portion 20A is formed in a portion of the case 20 where the bolt 40 is fixed. In this way, even when a conductive washer is used, an electric loop (an arrow A in FIG. 10) that circulates between the radiator plate 10, the bolt 40, and the case 20 through the refrigerant, as in the case of FIG. Can be eliminated.

  According to the cooling structure for an electric device according to the present embodiment, the washer 50 (or the insulating portion 20A) is provided between the heat radiating plate 10 (or the case 20) that defines the refrigerant passage 30 and the bolt 40, As described above, it is possible to suppress the generation of circulating current that flows between the heat sink 10 and the case 20 via the refrigerant and the bolt 40.

  Moreover, according to the cooling structure of the electric equipment according to the present embodiment, by using the washer 50 whose surface is insulated, the generation of circulating current can be suppressed with a simple configuration. In addition, the washer 50 is provided so as to be positioned on the wall surface of the opening 10A (20A) from the main surface of the heat sink 10 (or case 20), so that the main surface and the opening of the heat sink 10 (or case 20) are opened. It can suppress that the electric current from the volt | bolt 40 (or nut 41) flows into the heat sink 10 (or case 20) via the wall surface of hole 10A (20A). As a result, the generation of the circulating current can be effectively suppressed.

  Further, by providing the gasket 60 on the joint surface between the heat sink 10 and the case 20, it is possible to suppress the generation of a circulating current flowing between the heat sink 10 and the case 20 without using the bolt 40. Here, by using the gasket 60 having sealing properties and insulating properties, it is possible to suppress the generation of circulating current without increasing the number of components.

  The above configuration is summarized as follows. In other words, the cooling structure for an electric device according to the present embodiment includes a semiconductor element 95 as an “electric part”, a radiator plate 10 as a “first metal member” on which the semiconductor element 95 is mounted, and a radiator plate. 10 includes a metal different from that of the heat sink 10 and is joined to the heat sink 10 to form the refrigerant passage 30 as a “second metal member” case 20, and the heat sink 10 and the case 20 are fastened to “conductive”. A bolt 40 as a “fastening member” and a washer 50 (or an insulating portion 20A) as an “insulating part” provided between the bolt 40 and the heat sink 10 (or the case 20) are provided. In addition, the cooling structure for an electric device according to the present embodiment further includes a gasket 60 as “another insulating portion” provided on the joining surface of the heat radiating plate 10 and the case 20.

  The PCU 300 is an example of an “electric device”, and the “electric device” is not limited to this. As other “electric equipment” mounted on the vehicle, for example, motor generators 210 and 220 may be considered. Further, the “electric device” does not necessarily have to be mounted on the vehicle.

  Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the hybrid vehicle containing the cooling structure of the electric equipment which concerns on one embodiment of this invention. It is a figure explaining the drive unit in the hybrid vehicle shown by FIG. It is a circuit diagram which shows the structure of the principal part of PCU shown by FIG. 1, FIG. It is sectional drawing which shows the cooling structure of the electric equipment which concerns on one embodiment of this invention. It is the perspective view which showed the washer for electric corrosion prevention shown by FIG. It is VI-VI sectional drawing in FIG. It is sectional drawing which showed the gasket shown by FIG. It is a figure explaining the suppression mechanism of the circulating current through a refrigerant | coolant. It is sectional drawing which shows the modification of the cooling structure of the electric equipment which concerns on one embodiment of this invention. It is sectional drawing which shows the other modification of the cooling structure of the electric equipment which concerns on one embodiment of this invention.

Explanation of symbols

  1 hybrid vehicle, 10 heat sink, 10A, 20A opening, 20 case, 20A insulating part, 30 refrigerant passage, 40 bolt, 41 nut, 50, 50A washer, 50C, 60C conductive part, 50D, 60D insulating part, 51st 1 part, 52 2nd part, 60 gasket, 70A, 70B solder, 80A, 80B metal plate, 90 insulating plate, 95 semiconductor element, 100 engine, 150 shaft, 200, 210, 220 motor generator, 300 PCU, 300A, 400A Cable, 310 converter, 320 inverter, 321U, 322U U-phase arm, 321V, 322V V-phase arm, 321W, 322W W-phase arm, 330 controller, 340U, 340V, 340W, 350U, 350V, 350W Sa, 400 battery, 500 power split device, 550 reduction gear mechanism, 600 differential mechanism, 650 a drive shaft receiving portion 700 drive shaft, 800L, 800R driven wheels, 900 housing, 910, 920 terminal block.

Claims (6)

Electrical components,
A first metal member on which the electrical component is mounted;
A second metal member that includes a different metal from the first metal member and forms a refrigerant passage by being joined to the first metal member;
A conductive fastening member for fastening the first and second metal members;
A cooling structure for an electric device, comprising: an insulating portion provided between the fastening member and at least one of the first and second metal members.   The cooling structure for an electric device according to claim 1, wherein the insulating portion includes a washer for the fastening member. At least one of the first and second metal members has an opening through which the fastening member is inserted;
The cooling structure for an electric device according to claim 2, wherein the washer is provided so as to be positioned on a wall surface of the opening from at least one main surface of the first and second metal members.   The cooling structure for an electric device according to any one of claims 1 to 3, further comprising another insulating portion provided on a joint surface between the first and second metal members.   5. The cooling structure for an electric device according to claim 1, wherein the other insulating portion is a seal member that seals a joint portion between the first and second metal members.   An electric vehicle including the cooling structure for an electric device according to any one of claims 1 to 5.

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