JP2005245150A - Rotary electric machine for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary electric machine in which reliability of a power semiconductor element and a power module can be enhanced. <P>SOLUTION: The rotary electric machine for vehicle comprises a rotor 3 fixed with a fan 11 at the end part, a stator core 5, and brackets 9 and 10 constituting a housing for containing them wherein the brackets 9 and 10 hold the rotor 3 and fixed with a power module. The power module has a multilayer structure of a semiconductor element 20 and an insulating board 22 mounting the semiconductor element 20 wherein the insulating board 22 is fixed to the brackets 9 and 10. The insulating board 22 of the power module is fixed to the brackets 9 and 10 through a heat transfer member 24. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotating electrical machine for a vehicle, and more particularly to a power module structure of a rotating electrical machine on which a power semiconductor element for electric power (for example, a rectifying element, a voltage regulator, a power converter, etc.) is mounted.

  Patent Document 1 describes a module in which electronic components (capacitor, transistor, etc.) of an automatic voltage regulator of a vehicular generator are modularized on a board, and the board is fixed to the outer surface of a rear bracket of the generator. . The substrate is a printed circuit board made of resin, and has a structure that is mounted away from the bracket surface.

Japanese Patent Application Laid-Open No. H10-228688 describes a voltage regulator (a rectifier having a power transistor as a semiconductor rectifier built in a case) fixed to the outer surface of a generator housing (rear bracket). In the voltage regulator in this case, the case and its lid form a cooling fin, and the voltage regulator is fixed to the inner surface of the lid. Therefore, the heat generated from the power semiconductor rectifier of the voltage regulator is transmitted from the lid through the case to the rear bracket and dissipated, and a part of the heat is dissipated into the air.
JP-A-9-331645 JP-A-8-336258

  In the field of rotating electrical machines for vehicles, as described above, a voltage regulator and a power element such as a diode are mounted on a bracket of a generator (for example, an alternator). However, from the environmental point of view, as motor generators that have both drive and power generation functions have been developed by a single rotating electrical machine due to the need for engine idling stop, power converters such as inverters have been modularized. Mounting as a power module on rotating electrical machines (electric motors, generators) is also under consideration.

  The power module usually has a laminated structure of a power semiconductor element-solder-insulated substrate with copper bonded on both sides-solder-copper or aluminum base, and the base is attached to a heat sink via a heat conducting member. It has a structure.

  The reliability of the power module improves heat dissipation and the temperature of the semiconductor itself is also a problem. However, in order to ensure reliability, thermal fatigue of the solder that joins the semiconductor to the insulating substrate and the insulating substrate to the base The cycle becomes important. In particular, fatigue of solder between the insulating substrate and the base has a large difference in linear expansion between the insulating substrate and the base member, and has a great influence on reliability.

  This invention is made | formed in view of the above point, The objective is to provide the rotary electric machine for vehicles which improved the reliability of the power module.

In order to achieve the above object, the present invention basically provides a vehicular rotating electrical machine configured as follows.
One is a rotating electrical machine for a vehicle, a fan is attached to an end of the rotor, and a power module for electric power is attached to a bracket that holds the rotor and constitutes a housing of the rotating electrical machine. The power module includes a semiconductor element and an insulating substrate on which the semiconductor element is mounted, and the insulating substrate is attached to the bracket directly or via a heat transfer member.

  The insulating substrate is made of silicon nitride having a high bending strength.

  According to the present invention, it is possible to provide a vehicular rotating electrical machine with improved cooling and high reliability.

The best mode for carrying out the present invention will be described.
Embodiments of a rotating electrical machine for a vehicle according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a rotating electrical machine according to an embodiment of the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is a schematic diagram of a laminated structure of power modules used in the above embodiment. The rotary electric machine in a present Example has illustrated the alternator for vehicles as an example. In FIG. 1, the pulley 2 side attached to one end of the rotor shaft 1 is defined as “front side” and the opposite side is defined as “rear side”.

  A rotor 3 fitted with a field coil 4 is fixed to the rotor shaft 1, and a stator core 5 is disposed around the rotor 3 via a minute gap. A stator coil 6 is attached to the stator core 5. Both ends of the rotor shaft 1 are held by a pair of brackets (front bracket, rear bracket) 9 and 10 via bearings 7 and 8. Further, the front bracket 9 and the rear bracket 10 sandwich the stator core 5.

  Fans 11 are fixed to both ends of the rotor 3, and cooling air passes through the alternator through external air intake portions (not shown) provided in the bracket when the rotor 3 rotates. The cooling air takes heat generated from the field coil 4 and the stator core 5 of the alternator to increase the power generation efficiency.

  A slip ring 12 for supplying current to the field coil 4 is disposed around one end 1a of the rotor shaft protruding from one bracket (rear bracket) 10. The slip ring 12, an output terminal 13 for outputting the electric power induced in the stator core 6, a power module 14 for controlling the output electric power, and a rectifying diode (not shown) are attached to the outer surface of the rear bracket 10. It has been. These accessory parts are covered with a rear cover 15. Reference numeral 16 denotes a magnet for detecting the rotation of the rotor.

  As shown in FIG. 3, the power module 14 includes a power semiconductor element 20, for example, a MOS (complementary metal oxide semiconductor), an IGBT (insulated gate transistor), and the semiconductor element 20 includes a solder layer 21. Further, it is configured to be connected to the semiconductor element 20, the solder layer 21, the insulating substrate 22 laminate, and the bus bar 29 molded in the resin case 30 by wire bonding 28.

  The insulating substrate 22 of the power module 14 is attached to the rear bracket 10 with screws or the like. Grease 24 is interposed between the power module mounting surface, that is, the insulating substrate 22 and the rear bracket 10.

  The inner surface of the rear bracket opposite to the power module mounting surface is opposed to one end surface of the rotor 3 to which the fan 11 is mounted. The rear bracket 10 to which the power module 14 is attached, the insulating substrate 22, and the semiconductor element 20 form a laminated structure. The insulating substrate 22 is made of silicon nitride or the like having a high bending strength. Fins 17 having a heat radiation function are provided on the inner surface of the rear bracket 10 to which the power module 14 is attached.

  In the present embodiment, a semiconductor element for power adjustment is illustrated as the power module 14, but the power module may be a rectifier diode used in an AC rotating machine such as an alternator.

  The power module 14 is accommodated in a case 26 formed on the surface of the insulating substrate 22 and covered with a cover 27. Further, the power semiconductor element 20 of the power module 14 is connected to the bus bar 29 via the wire bonding 28.

  According to the present embodiment, the rear bracket 10 can be used as a heat radiating plate, and the heat generated by the semiconductor element 20 can be radiated by the insulating substrate 22 in surface contact via the grease 24 that is a heat transfer member. Further, the rear bracket 10 and the insulating substrate 22 are in surface contact with slip, and the difference in linear expansion generated between the rear bracket 10 and the insulating substrate 22 can be absorbed by the slip. Therefore, the reliability can be improved by improving the cooling of the power module 14 and omitting the solder under the insulating substrate.

The longitudinal cross-sectional view of the rotary electric machine for vehicles of an Example. The partial expanded sectional view of the rotary electric machine for vehicles of an Example. The schematic diagram of the power module used for the rotary electric machine for vehicles of an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Rotor, 10 ... Bracket (rear bracket), 11 ... Fan, 14 ... Power module, 15 ... Rear cover, 17 ... Fin, 20 ... Power semiconductor element, 22 ... Insulating substrate

Claims (3)

A vehicular rotating electrical machine comprising a rotor having a fan attached to an end thereof, a stator core, and a bracket constituting a housing for housing the rotor, the bracket holding the rotor and having a power module for electric power attached thereto In
The vehicular rotating electrical machine according to claim 1, wherein the power module has a laminated structure including a semiconductor element and an insulating substrate on which the semiconductor element is mounted, and the insulating substrate is attached to the bracket. The rotating electrical machine for a vehicle according to claim 1,
The vehicular rotating electrical machine, wherein the insulating substrate of the power module is attached to the bracket via a heat transfer member. The rotating electrical machine for a vehicle according to claim 1 or 2,
The electric rotating machine for vehicles, wherein the insulating substrate of the power module is made of silicon nitride.

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