JPH0793805B2 - AC generator for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vehicle alternator equipped with a rectifying device,
In particular, the present invention relates to a vehicle AC generator that is suitable for a small size, light weight, and high output by improving the cooling performance of a rectifier.

[Conventional technology]

A conventional rectifier for an alternator for a vehicle is disclosed in JP-A-61-1805.
As described in No. 56, a plurality of rectifying elements with different polarities are installed in each pair of cooling fins, and a synthetic resin insulating bush is sandwiched between the pair of cooling fins. Thus, the fins are electrically insulated from each other and a gap is provided between the two fins.

[Problems to be solved by the invention]

However, in the above-mentioned prior art, no consideration is given to the heat conduction between the pair of cooling fins, and the cooling fin of the pair of cooling fins that is in contact with the bracket for fixing the rectifying device, that is, the (-) side Regarding the cooling fin, high cooling performance can be obtained by cooling with cooling air and heat conduction to the bracket, but the other cooling fin fixed via an insulating bush, that is, the (+) side cooling fin. With regard to (2), since the insulating bush has poor heat conductivity, there is almost no cooling due to heat conduction in that part, and cooling is performed only with cooling air, and the cooling performance is poor compared to the cooling fins mentioned at the beginning. There is a problem that the temperature of the rectifying element provided in the cooling fin becomes high.

An object of the present invention is to provide a vehicle AC generator equipped with a rectifying device with improved cooling performance of cooling fins.

[Means for solving problems]

The above-mentioned object is to conduct heat to both surfaces of the glass cloth as a means for flowing the heat of the (+) side cooling fin to the (−) side cooling fin between the (−) side cooling fin and the (+) side cooling fin. This is achieved by arranging a sheet-shaped electric insulating member made of a material having a good thermal conductivity and an electrical insulation, which is coated with a silicone rubber having a good property, and a spacer member made of a material having a good thermal conductivity.

[Action]

The heat generated by the rectifying element provided in the (+) side cooling fin diffuses in the (+) side cooling fin and is transmitted to the cooling air. On the other hand, the heat generated by the rectifying element provided in the (−) side cooling fin diffuses in the (−) side fin and is transmitted to the cooling air, and the (−) side cooling fin is in contact with the bracket. It is also transmitted to this bracket. Therefore, the (−) side cooling fin has a lower temperature than the (+) side cooling fin because heat is conducted to the bracket. Therefore,
There is a temperature difference between the (+) side cooling fin and the (-) side cooling fin, and the heat of the (+) side cooling fin has good thermal conductivity and is electrically insulating disposed between the two cooling fins. The sheet-shaped electric insulating member made of the above material and the spacer member made of the material having good thermal conductivity are transmitted to the (−) side cooling fin, and are transmitted from this cooling fin to the bracket. As the electric insulating member, a sheet-like member in which both surfaces of glass cloth are coated with silicon rubber having heat conductivity is suitable.

By the way, in general, a material having a good electrical insulation usually has a poor thermal conductivity, and even if a material having a good thermal conductivity is used as a material for the electrical insulating member, there is a limit to the improvement of the thermal conductivity. . That is, it is difficult to achieve both electrical insulation and thermal conductivity. In the present invention, a thin sheet-like material such as glass cloth is used as the electric insulating material to prevent deterioration of thermal conductivity, and the both sides thereof are coated with a silicon rubber having thermal conductivity so that thermal conductivity can be improved. The heat resistance of the electrical insulating member is reduced when the heat of the (+) side cooling fins flows to the (-) side cooling fins. Further, by disposing the spacer member separately from the electrically insulating member, it is not necessary for the spacer member to have electrical insulation properties, and it is possible to use one having extremely good thermal conductivity. Thus, by combining the sheet-like electric insulating member and the spacer member, heat can be satisfactorily flown from the (+) side cooling fin to the (-) side cooling fin while ensuring the electric insulation. Therefore, the cooling performance of the (+) side cooling fin is improved, and the rectifying element provided in the (+) side cooling fin can be effectively cooled.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

Referring to FIG. 1, an automotive alternator according to an embodiment of the present invention has a rotor 1, which is a bracket 2,3.
It is rotatably supported using bearings 4 and 5. The rotor 1 passes through a pulley 6 and is rotated by a motor. Further, a stator 7 is located around the rotor 1, and the stator 7 is
It is sandwiched by a pair of brackets 2 and 3 and generates an alternating current. A full-wave rectifier 8 is attached to the bracket 2, and the alternating current generated by the stator 7 is rectified by the rectifier 8 and taken out as an output.

Cooling fans 9 and 10 are attached to both end faces of the rotor, and a plurality of ventilation holes 11 and 12 are provided in the brackets 2 and 3, and the cooling fans 9 and 10 rotating with the rotor allow the ventilation holes 11 and 12 to pass through. The cooling air of the air as shown by the arrow is generated, whereby the rotor 1, the stator 7, and the rectifying device 8 are cooled.

As shown in an enlarged view in FIGS. 2 and 3, the rectifying device 8 has a pair of generally horseshoe-shaped cooling fins 20 and 21, and these cooling fins 20 and 21 are provided on the side opposite to the bracket 2. A plurality of recesses 22, 23 are formed on the surface, and these recesses 22, 23 are formed.
The rectifying elements having different polarities, that is, the diode elements 24 and 25 are mounted on the cooling fin 20 with the cooling fin 20 as part of the (-) side circuit and the cooling fin 21 as part of the (+) side circuit. That is, the diode elements 24 each function as a (−) side diode element by connecting the cathode side to the common fin 20 of the recess 22 and the terminal plate 26 to the opposite pole side, and the diode elements 25 are respectively connected to the anode side. It is connected to the common fin 21 of the concave portion 23 and the terminal plate 27 is connected to the opposite pole side to function as a (+) side diode element.

On the surface of the (−) side cooling fin 20 on the side opposite to the bracket 2, as a means for forming a gap between the cooling fins 20 and 21, a protrusion 28 is formed.
Is provided. Since the protrusion 28 forms a part of the cooling fin 20, it is made of a material having excellent thermal conductivity, such as copper or aluminum, like the cooling fin. Between the protrusion 28 of the (−) side cooling fin 20 and the (+) side cooling fin 21, the insulating member, that is, the insulator thin film 29 made of a material having excellent thermal conductivity and electrical insulation is narrowed. I have it. This insulator thin film 29 can be made of, for example, an insulating sheet known as a thermoflow sheet in which both surfaces of a glass cloth are coated with special silicon having thermal conductivity.

The cooling fins 20 and 21 are integrally fixed to and held by the bracket 2 by the bolts 30 and the nuts 31 in a state where the insulator thin film 29 is sandwiched by the protrusions 28.

According to such a configuration, the heat radiation of the cooling fins 20 and 21 to the cooling wind induced by the cooling fan 9 is caused by the gap between the cooling fins formed by the protrusion 28 provided on the (−) side cooling fin 20. The area is increased, and the heat generated by the (−) side diode element 24 and the (+) side diode element 25 is diffused in the (−) side cooling fin 20 and the (+) side cooling fin 21, respectively, and the large heat is dissipated. It is transmitted to the cooling air by the area. Further, since the (−) side cooling fin 20 is in contact with the bracket 2, its heat is also directly transmitted to this bracket 2 as indicated by arrow A. In addition, a part of the heat is transmitted to the bolt 30 and the nut 31 through the contact portion with the bolt 30.
Is transmitted to bracket 2. Therefore, the (-) side cooling fin
The temperature of 20 is lower than that of the (+) side cooling fin 21 because heat is conducted to the bracket 2. Therefore, a temperature difference occurs between the (+) side cooling fin (20) and the (-) side cooling fin 21, and the heat of the (+) side cooling fin 21 is equal to that of the two cooling fins.
It passes through the insulator thin film 29 having excellent heat conductivity sandwiched between 20, 21 and the protrusion 28 having good heat conductivity, and is transmitted to the (-) side cooling fin 20 as indicated by an arrow B, and this cooling fin It is transmitted from 20 to bracket 2. A part of the heat is also transmitted to the bracket 2 from the bolt 30 and the nut 31. By the way, in general, a material having a good electric insulation is not so good in thermal conductivity, and even if a material having a good thermal conductivity is used as the material of the insulator thin film 29, there is a limit to the improvement of the thermal conductivity. . That is, it is difficult to achieve both electrical insulation and thermal conductivity. In this embodiment, by thinning the insulator thin film 29 into a sheet shape, the thermal resistance of the insulator thin film 29 when the heat of the (+) side cooling fin flows to the (−) side cooling fin is reduced. Further, the protrusion 28 arranged between the (+) side cooling fin and the (−) side cooling fin together with the insulator thin film 29 does not need to have electrical insulation, and is a cooling fin excellent in thermal conductivity. The same conductor can be used. Thus, by combining the sheet-shaped insulator thin film 29 and the protrusion 28, heat can be satisfactorily flown from the (+) side cooling fin to the (-) side cooling fin while ensuring electrical insulation. Therefore, the cooling performance of the (+) side cooling fin 21 is improved to the same extent as the (−) side cooling fin 20, and not only the diode element 24 provided in the (−) side cooling fin 20 but also the (+) side cooling fin. The diode element 25 provided on the fin 21 can also be effectively cooled.

FIG. 4 shows the experimental results of the temperature rise of the diode elements in the conventional vehicle AC generator and the vehicle AC generator of the above embodiment. In the figure, A is a diagram showing a temperature rise value of a (+) side diode element of a conventional product, B is a diagram showing a temperature rise value of the same (−) side diode element, and C is a present embodiment. It is a diagram which shows the temperature rise value of the (+) side diode element of a product, and D is a diagram which shows the temperature rise value of the same (−) side diode element. From this experimental result, it can be seen that the temperature of the (+) side diode element can be reduced by about 10 ° C. near the maximum temperature in the present example, as compared with the conventional product.

In the above embodiments, the projection 28 is provided on the cooling fin 20 as a means for forming a gap between the cooling fins 20 and 21. However, this is an example, and other configurations can be adopted as a means for forming the void. FIGS. 5 and 6 show another embodiment in this regard, and the same members as those shown in FIGS. 1 to 3 are designated by the same reference numerals.

In the embodiment shown in FIG. 5, the (-) side cooling fin 20 is provided.
Instead of providing the protrusion 28 on the cooling fin 20, the cooling fin 20 is partially bent to form a bent portion 40, and the insulator thin film 29 is sandwiched between the bent portion 40 and the (+) side cooling fin 21. It was configured.

Further, in the embodiment shown in FIG. 6, instead of providing the projection 28 on the cooling fin 20, it is made of a material having excellent thermal conductivity, for example, a metal such as copper or aluminum, or a ceramic having good thermal conductivity. A separate bush 41 is sandwiched between the pair of cooling fins 20 and 21, and the insulator thin film 29 is attached to the bush 4
Between 1 and at least one of the cooling fins 20 and 21,
In the illustrated embodiment, the bush 41 and the (+) side cooling fin 21 are sandwiched between them. However, when a metal such as copper or aluminum is used as the material of the bush 41, the bush 41 does not have electric insulation, but even in this case, the insulation thin film 29 maintains the electric insulation. Since there is no problem, it is possible to achieve both electrical insulation and thermal conductivity.

It will be apparent that the same effects as those of the embodiment shown in FIGS. 1 to 3 can be obtained by such a configuration.

〔The invention's effect〕

As is clear from the above, according to the vehicle alternator of the present invention, it is possible to provide a gap between the two cooling fins,
The heat dissipation area of the cooling fin can be made large, and the heat generated by the (+) side diode element is transmitted to the bracket through the (+) side cooling fin, the electrically insulating member and the (-) side cooling fin. Therefore, high cooling performance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an entire vehicular AC generator according to an embodiment of the present invention, and FIG. 2 is a half sectional view of a rectifying device for the vehicular AC generator. FIG. 3 is a plan view of the rectifier, FIG. 4 is a view showing an experimental result of measuring the temperature rise of the cooling fins of the vehicle AC generator and the conventional product, and FIG. FIG. 6 is a partial sectional view of a vehicle AC generator according to another embodiment of the present invention, and FIG. 6 is a partial sectional view of a vehicle AC generator according to still another embodiment of the present invention. Explanation of symbols 8 …… Rectifier, 20,21 …… Cooling fin 24,25 …… Diode element (rectifier) 28 …… Projection (means for forming void) 29 …… Insulator thin film (electrically insulating member)

Claims (4)

[Claims] 1. A plurality of (-) side cooling fins fixed to a bracket so as to be able to conduct heat, and a plurality of (+) side cooling fins which are arranged with a space for the (-) side cooling fins. In a vehicular AC generator equipped with a rectifying device having a different polarity rectifying element, the heat of the (+) side cooling fin is provided between the (-) side cooling fin and the (+) side cooling fin. As a means for flowing the (-) side cooling fin, a sheet-like electric insulating member made of a material having good thermal conductivity and electrical insulation in which both surfaces of the glass cloth are coated with silicon rubber having thermal conductivity, and a good thermal conductivity An alternating current generator for a vehicle, characterized in that a spacer member made of a conductive material is arranged. 2. The vehicle according to claim 1, wherein the spacer member is a protrusion provided on at least one of the (-) side cooling fin and the (+) side cooling fin. AC generator. 3. The spacer member is a bent portion provided on at least one of the (−) side cooling fin and the (+) side cooling fin.
The vehicle AC generator according to the item. 4. The vehicle AC generator according to claim 1, wherein the spacer member is a bush separate from the (-) side cooling fin and the (+) side cooling fin. Machine.