JP2002119029A - Ac generator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC generator for a vehicle where the size of commutator element can be made small and reliability can be improved. SOLUTION: A commutator device, included in the AC generator for a vehicle, is constituted by inserting forcibly a disk 160 of the commutator element 55 in a drive hole formed in a thermally radiating plate 53. The disk 160 is formed of chromium copper, which is harder than the radiating plate 53, formed by using tough pitch copper or Mg base aluminum. The position of a soldering surface 168 of the disk 160 is set at a position lower than the upper end position of a knurled part 166.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle alternator mounted on a passenger car, a truck and the like.

[0002]

2. Description of the Related Art An alternator for a vehicle generates electric power by motive power transmitted from an engine, charges a battery, and ignites the engine, supplies power to lighting and other various electric components. In order to maintain or improve market competitiveness, reduction in size and weight, increase in output, and cost reduction are important issues. Among these problems, as one of means for achieving a reduction in size and weight and a reduction in cost, there is known a method in which aluminum is used as a material of a radiator plate of a rectifier incorporated in a vehicle alternator. However, it is not easy to solder the rectifying element to the aluminum heat sink. For example, it is difficult to directly solder the aluminum radiator plate. Therefore, it is necessary to employ a method of plating the radiator plate and then soldering the rectifying element, which is troublesome and costly. For this reason, when a rectifying element is joined to an aluminum radiator plate, see Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 2671, a knurled portion provided on the outer periphery of a metal pedestal of a rectifying element is press-fitted into a through-hole or a concave portion formed in an aluminum radiator plate to provide mechanical fixation and electrical fixing. A technique for realizing both simple connections is widely used. Such a technique is also effective when the material of the radiator plate is copper, and soldering work is not required when attaching the rectifying element to the radiator plate, so that the working efficiency can be improved.

FIG. 7 is a partial sectional view of a conventional rectifier, and mainly shows a structure around a rectifier. FIG.
In the conventional rectifier shown in FIG. 1, a rectifier 102 is driven and fixed in a driving hole formed in a heat sink 100.
No need for soldering. This rectifying element 102
Semiconductor pellets 108 are solder 106
And the semiconductor pellet 10
A lead 112 is soldered to the upper part of the chip 8 by solder 110, and the entire semiconductor pellet 108 is covered with a protective layer 114 made of silicon rubber or resin. Further, in the rectifier shown in FIG. 7, the semiconductor pellet 1 of the disk 104 is larger than the height of the end face of the heat sink 100.
08 is set low.

FIG. 8 is a diagram showing a partial structure of another conventional rectifier. Compared to the rectifier shown in FIG.
The thickness of the disk 104a included in the rectifying element 102a is increased, and the resin ring 11 is formed around the protective layer 114a.
6 is different.

FIG. 9 is a view showing a partial structure of still another conventional rectifier. The difference from the rectifier shown in FIG. 8 is that the resin ring 116 is eliminated by extending the outer peripheral portion of the disk 104b to the lead 112 side.

[0006]

In the conventional rectifier shown in FIG. 7, when the disk 104 is made of copper and the radiator plate 100 is made of copper or high-strength aluminum, the disk 104 is radiated from the radiator plate. A large stress is generated in the semiconductor pellet 108 when the semiconductor pellet 108 is implanted into the semiconductor chip 100, causing mechanical damage to the semiconductor pellet. In addition, an excessive stress is always applied to the solder 106 joining the disk 104 and the semiconductor pellet 108. State
There has been a problem that thermal fatigue is likely to occur and reliability is reduced.

In order to prevent such mechanical damage to the semiconductor pellet and thermal fatigue to the solder, the thickness of the disk is set to be equal to or larger than the thickness of the radiator plate as in the rectifier shown in FIG. 8 or FIG. However, in this case, there is a problem that the amount of material used for the disk increases and the size of the rectifying element increases. Further, in the rectifying device shown in FIG. 8, the resin ring 116 is required for the rectifying element, which increases the number of components, which is not preferable from the viewpoint of cost reduction and the like. Further, the rectifying device shown in FIG. 9 is not preferable because the processing of the disk is not easy and the process becomes complicated.

The present invention has been made in view of the above points, and an object of the present invention is to reduce the size of a rectifying element and improve the reliability of a vehicle AC generator. Is to provide.

[0009]

In order to solve the above-mentioned problems, an automotive alternator according to the present invention has a heat radiating plate provided with a rectifying device including a plurality of rectifying elements and a heat radiating plate. And a semiconductor element including a semiconductor pellet and a disk on which the semiconductor pellet is disposed, and the disk is formed of a material harder than the heat sink. Since the disk is made of a hard material, the mechanical damage that occurs in the semiconductor pellet when the rectifying element is pressed into the driving hole of the heat sink can be reduced, and the stress that occurs in the solder between the disk and the semiconductor pellet can be reduced. Therefore, the reliability can be improved by reducing the occurrence of thermal fatigue.

[0010] Specifically, it is desirable that the material of the above-mentioned disk is chromium copper and the material of the heat sink is copper, aluminum or an aluminum alloy. By forming the disk using chromium copper, which is a copper alloy, it is possible to realize a disk that is harder than copper or aluminum, which is the material of the heat sink. In particular, when aluminum or an aluminum alloy is used for the heat sink, it is possible to reduce the weight and cost of the rectifier and the vehicle alternator as a whole.

A knurled surface is formed on the outer periphery of the disk at a position facing the heat radiating plate, and the position of the soldering surface of the semiconductor pellet on the disk is higher than the upper end position of the knurled surface. It is desirable to set low. By forming the disk with a hard material, even if the position of the soldering surface on the disk is lower than the upper end position of the knurled surface, that is, the end surface position of the heat sink, excessive stress on this soldering surface Can be prevented from occurring. For this reason, the thickness of the disk can be reduced, and the size of the rectifying element can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle AC generator according to an embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing the overall configuration of an automotive alternator. The automotive alternator 1 shown in FIG. 1 includes a stator 2, a rotor 3, a brush device 4, a rectifier 5, a frame 6, a rear cover 7, a pulley 8, and the like.

The stator 2 includes a stator core 21 and three-phase stator windings 23 wound at predetermined intervals around a plurality of slots formed in the stator core 21.

The rotor 3 has a field winding 31 formed by winding an insulated copper wire in a cylindrical and concentric manner, each of which has a length of 6 mm.
The rotation axis 33 is provided by the pole core 32 having the claw portions.
Has a structure sandwiched from both sides. Also,
An axial cooling fan 34 is attached to the end face of the pole core 32 on the front side by welding or the like to discharge the cooling air sucked from the front side in the axial direction and the radial direction. Similarly, a centrifugal cooling fan 35 is attached to the end face of the pole core 32 on the rear side by welding or the like in order to radially discharge the cooling air sucked from the rear side.

The brush device 4 is composed of the rectifier 5 and the rotor 3
For passing an exciting current to 31 in the field winding of
Slip ring 3 formed on rotating shaft 33 of rotor 3
Brushes 41 and 42 for pressing the respective brushes 6 and 37 are provided.

The rectifier 5 rectifies a three-phase AC voltage, which is an output voltage of the three-phase stator winding 23, to obtain DC output power, and includes a terminal block including wiring electrodes therein. 51, a positive-side radiator plate 52 and a negative-side radiator plate 53 arranged at predetermined intervals, and a plurality of rectifying elements 54, 55 attached by press-fitting into driving holes provided in the respective radiator plates. It is comprised including. Details of the rectifier 5 will be described later.

The frame 6 houses the stator 2 and the rotor 3, supports the rotor 3 so as to be rotatable about a rotation shaft 33, and has the outer periphery of the pole core 32 of the rotor 3. Is fixed to the stator 2 disposed with a predetermined gap therebetween. The frame 6 is provided with a cooling air discharge window 61 at a portion facing the stator winding 23 protruding from the axial end surface of the stator core 21 and a cooling air intake window 62 at the axial end surface. I have.

The rear cover 7 includes a brush device 4, a rectifying device 5 and an I
This is to cover the entire C regulator 12 and protect them.

AC generator 1 for vehicle having the above structure
Is connected to the pulley 8 via a belt or the like by an engine (not shown).
When the rotational force is transmitted, the rotor 3 rotates in a predetermined direction. In this state, by applying an excitation voltage to the field winding 31 of the rotor 3 from the outside, each claw of the pole core 32 is excited, and a three-phase AC voltage can be generated in the stator winding 23. The DC output power is taken out from the output terminal of the rectifier 5.

Next, details of the rectifier 5 will be described. FIG. 2 is a plan view showing a detailed structure of the rectifier 5. FIG. 3 shows a vehicle alternator 1 including a rectifier 5.
5 is a partial cross-sectional view showing a cross-sectional structure near the rear cover 7 and the rectifier 5. FIG. 4 shows the negative-side heat sink 53.
It is a figure showing the detailed shape of. FIG. 5 is a diagram showing the structure of a single rectifying element. In the following, mainly the negative electrode side heat sink 53
And the rectifying element 55 will be described.
The same applies to the rectifying element 54 and the rectifying element 54, and a detailed description is omitted.

As shown in FIG. 4, four driving holes 150 for press-fitting and mounting the rectifying element 55 are formed in the negative-side radiation plate 53. These driving holes 150 are through holes, and the diameter thereof is set to a value slightly smaller than the outer diameter of the rectifying element 55.

The rectifying element 55 includes a disk 160, a semiconductor pellet 162, and leads 164. The disk 160 has a knurled portion 166 on the outer periphery,
It has a cylindrical shape in which a concave portion 167 is formed on one end surface, and the bottom surface of the concave portion 167 becomes a soldering surface 168 for joining the semiconductor pellet 162. For example, in the present embodiment, the disk 160 is formed of chromium copper having a chromium (Cr) content of about 1.0 wt%. The heat radiating plate 53 is made of tough pitch copper (C1100) or high-strength Mg-based aluminum (A5052).

In the rectifying element 55, a semiconductor pellet 162 is soldered on a disk 160 by solder 161.
Further, a lead 164 is provided above the semiconductor pellet 162.
Are soldered by solder 163. Further, a protective layer 165 made of silicon rubber or resin is formed so as to cover the entire semiconductor pellet 162.

Further, in this embodiment, the position of the soldering surface 168 of the disk 160 is set lower than the upper end position of the knurl portion 166, that is, the end surface position of the heat sink 53.

As described above, in this embodiment, the heat sink 53
Is formed of tough pitch copper or a high-strength aluminum alloy, the disk 160 of the rectifying element 55 is formed of chromium copper, which is a harder material. For this reason, the soldering surface 168 on the disk 160 is
Even if it is set lower than the upper end position of 66, it is possible to prevent the generation of excessive stress in the semiconductor pellet 162, and further, it is possible to prevent the generation of excessive stress in the solder 161 on the soldering surface 168. . Therefore, mechanical damage to the semiconductor pellets can be prevented, and the life can be prevented from being shortened due to thermal fatigue, and the reliability of the rectifier 5 and the vehicle alternator 1 as a whole can be improved. Further, since the soldering surface 168 can be set lower than the upper end position of the knurl portion 166, the thickness of the disk 160 can be reduced, and the size of the rectifying element 55 can be reduced.

When a high-strength aluminum alloy or aluminum is used as the heat sink 53, the weight and cost can be reduced as compared with the case where copper is used.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the embodiment described above,
The disk 160 such as the rectifying element 55 is formed of chromium copper, and the radiator plate 53 and the like are formed of tough pitch copper or Mg-based aluminum. May be a combination other than these.

In the above-described embodiment, the heat sink 53
However, as shown in FIG. 6, a recessed punched hole may be formed in the heat sink 53a, and the disk 160a of the rectifying element 55a may be pressed into the recess. Even in this case, the disk 160
It is possible to reduce distortion due to excessive stress generated in the solder 161 on a.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of a vehicle alternator.

FIG. 2 is a plan view showing a detailed structure of a rectifier.

FIG. 3 is a partial sectional view of an automotive alternator including a rectifier.

FIG. 4 is a diagram showing a detailed shape of a negative electrode side heat sink.

FIG. 5 is a diagram showing a structure of a rectifying element alone.

FIG. 6 is a partial sectional view showing a modification of the rectifier.

FIG. 7 is a partial cross-sectional view of a conventional rectifier.

FIG. 8 is a partial sectional view of a conventional rectifier.

FIG. 9 is a partial sectional view of a conventional rectifier.

[Explanation of symbols]

 52, 53 Heatsink 54, 55 Rectifier 160 Disk 161 163 Solder 162 Semiconductor pellet 164 Lead 165 Protective layer 166 Knurl 167 Concave 168 Soldering surface

Claims (2)

[Claims] 1. An automotive alternator in which a rectifier including a plurality of rectifying elements and a radiator plate is incorporated, wherein the radiator plate has a driving hole into which the rectifier element is press-fitted. The element is configured to include a semiconductor pellet and a disk on which the semiconductor pellet is disposed, wherein the disk is formed of a material harder than the heat sink. 2. The disk according to claim 1, wherein a knurled surface is formed on the outer periphery of the disk at a position facing the heat sink, and a position of a soldering surface of the semiconductor pellet on the disk is the position of the knurl. An alternator for a vehicle, wherein the alternator is set lower than the upper end position of the knurled surface.