JP2002142424A - Alternator for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously attain high output and improvement for mass production in an alternator for vehicle by ensuring high reliability of diode through improvement of the cooling performance for generation of heat of diode with a simplified structure. SOLUTION: The alternator comprises a pre-bracket 10 and a post-bracket 11 for supporting a stator 40 and a rotating shaft 6, a rectifier 35 consisting of a diode minus cooling plate 21 and a diode plus cooling plate 22 mounting a diode 32 and a fan 16 for blowing the air to the surrounding of the diode plus cooling plate 22. A cooling member 25 is provided at the position within the ventilating route of the fan 16 through thermal connection to the diode plus cooling plate 22 or rectifier 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular alternator, and more particularly to a vehicular alternator having a rectifier.

[0002]

2. Description of the Related Art A vehicle alternator, commonly called an alternator, is driven by an engine such as an internal combustion engine of a vehicle to supply power to various electric components in the vehicle. Usually, the vehicle alternator is driven by a belt by a pulley provided on a drive shaft of the internal combustion engine. The output generated by the vehicle AC generator is AC, but the number of revolutions of the internal combustion engine that performs DC conversion with a rectifier having a diode attached to the generator varies, but must be supplied to electrical components. The required voltage requires a constant voltage of, for example, 13.5 V. Therefore, the DC output voltage of the generator is detected by the voltage regulator, and the voltage is maintained at a constant voltage by adjusting the current supplied to the exciting coil. The excitation coil, the stator coil, the diode, and the voltage regulator in the automotive alternator naturally generate heat because current flows during power generation.
Therefore, it is necessary to cool them so as not to overheat. Conventionally, in order to remove this heat generation, these are air-cooled by fans provided before and after the rotor in the axial direction.

[0003] However, as the power consumption of the electrical components increases, the output of the vehicle alternator is required to increase, and the exciter coil, the stator coil, the diode, and the heat generation of the voltage regulator in the vehicle alternator. Is increasing. For this reason, it is conceivable to increase the cooling capacity by increasing the fan airflow.However, the temperature of the exciting coil and stator coil can be relatively easily reduced by increasing the fan airflow, but the diode has dimensional restrictions. Due to the large size, it is difficult to sufficiently reduce the temperature only by increasing the fan airflow, and how to cool the diode is a point for improving the output of the AC generator for air-cooled vehicles.

Japanese Patent Laid-Open Publication No. Hei 8-126274 discloses a conventional rectifying device for a vehicle AC generator, in which a plurality of rectifying diodes are held in an end frame that constitutes an outer frame of the generator. ) Side cooling fins and (+) side cooling fins and a heat conductive insulating sheet member interposed therebetween so as to be superimposed, and elastic heat conductive paste-like insulation is provided between each cooling fin and the heat conductive insulating sheet member. By using a rectifier with a member or a heat conductive sheet-shaped insulating member interposed, the temperature difference between the (+) side cooling fins and the (−) side cooling fins is reduced, thereby improving the cooling efficiency of the rectifier. It is shown.

[0005]

However, Japanese Unexamined Patent Publication No. 8-126274 discloses that heat generated by a rectifier diode provided on a (+) side cooling fin is supplied to a (−) side via a heat conducting member. It has been shown that the heat is transmitted to the cooling fins and is cooled by being transferred to the end frame together with the heat generated by the (−) side rectifier diode, and that the heat transfer is improved. In order to cope with the further increase, it is desired to further improve the cooling performance against heat generation of the diode without largely changing the conventional structure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle alternator which has a simple structure and greatly improves the cooling performance against the heat generated by the diode, thereby ensuring the reliability of the diode and achieving both high output and mass productivity. Is to get

[0007]

A first feature of the present invention to achieve the above object is that a rotating shaft through which a rotational force is transmitted from a vehicle engine via a pulley, and which is fixed to the rotating shaft, A rotor that is excited by an exciting coil, a stator that is disposed outside the rotor and has a stator coil wound thereon, and that supports the stator from a pulley side and that the rotating shaft is supported via a bearing. A front bracket for supporting the stator, a rear bracket for supporting the stator from the side opposite to the pulley, and supporting the rotary shaft via a bearing, and a diode minus cooling in which a plurality of negative poles on the negative output side of the vehicle alternator are fixed. Plate, a diode plus cooling plate to which a plus output side diode of a plurality of vehicle alternators is fixed, and an electrical connection between the diode minus cooling plate and the diode plus cooling plate. A vehicle comprising: an insulating member that insulates, a diode minus cooling plate, a fixing member that fixes the insulating member and the diode plus cooling plate to the rear bracket, and a fan that ventilates the bracket. AC generator for
A cooling member is provided in the ventilation path of the fan and thermally connected to the diode plus cooling plate.

Preferably, the cooling member is thermally connected to the diode plus cooling plate while maintaining electrical insulation, and the cooling member is thermally connected to the fixing member, and the fixing member is thermally conductive. And a thermally connected and fixed to the rear bracket.

Preferably, a mold terminal having good heat conduction and electrical insulation is interposed between the cooling member and the diode plus cooling plate.

A second feature of the present invention is that a rotating shaft to which torque is transmitted from a vehicle engine via a pulley, a rotor fixed to the rotating shaft and excited by an exciting coil, And a stator on which a stator coil is wound, and while supporting the stator from the pulley side,
A front bracket that supports the rotating shaft via a bearing,
A rear bracket that supports the stator from the side opposite to the pulley and supports the rotating shaft via a bearing, a diode minus cooling plate to which a minus output side diode of a plurality of vehicle alternators is fixed, and a plurality of vehicles A diode plus cooling plate to which a plus output side diode of the alternator is fixed, an insulating member that electrically insulates the diode minus cooling plate and the diode plus cooling plate, and the diode minus which is sequentially arranged from the rear bracket side. In a vehicle alternator including a cooling plate, a fixing member for fixing the insulating member and the diode plus cooling plate to the rear bracket, and a fan that ventilates the bracket, the fixing member penetrates the insulating member. The diode minus cooling plate and the diode plug. Lies in the formation of the gap between the cooling plate.

A third feature of the present invention is that a rotating shaft to which torque is transmitted from a vehicle engine via a pulley, a rotor fixed to the rotating shaft and excited by an exciting coil, And a stator on which a stator coil is wound, and while supporting the stator from the pulley side,
A front bracket that supports the rotating shaft via a bearing,
A rear bracket that supports the stator from the side opposite to the pulley and supports the rotating shaft via a bearing, a diode minus cooling plate to which a minus output side diode of a plurality of vehicle alternators is fixed, and a plurality of vehicles A diode plus cooling plate to which the plus output side diode of the alternator is fixed, an insulating member that electrically insulates the diode minus cooling plate and the diode plus cooling plate, and the diode minus which is arranged in order from the rear bracket side. An alternator for a vehicle comprising a cooling plate, a fixing member for fixing the insulating member and the diode plus cooling plate to the rear bracket, and a fan that ventilates the inside of the bracket, wherein the diode minus cooling plate and the rear bracket are provided. And a cylindrical spacer through which the fixing member penetrates is provided. In that the Domainasu cooling plate to form a gap between the rear bracket.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the second and subsequent embodiments, some of the components common to the first embodiment are omitted, and
A duplicate description will be omitted. The same reference numerals in the drawings of the respective embodiments indicate the same or corresponding components.

First, a first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a vehicle alternator according to a first embodiment of the present invention. FIG. 2 is an explanatory view showing a state in which a cooling member of a rectifier portion of the vehicle alternator of FIG. 1 is omitted.
FIG. 4 is a sectional perspective view of a cooling member used in the automotive alternator of FIG. 1, and FIG. 4 is a sectional perspective view showing a modification of the cooling member of FIG.

The rotor 1 is fixed to a rotating shaft 6,
Excited by the exciting coil 4, the rotor claws 2 generate N and S poles in the circumferential direction of the rotor according to the number of poles. DC current is supplied to the exciting coil 4 by a slip ring. The slip ring includes a brush 9 mainly composed of carbon held by a brush holder and a brush ring 34 fixed to the rotating shaft 6. Note that a connection terminal 7 is provided between the slip ring and the exciting coil 4, and a lead wire from the slip ring and a conductive wire of the exciting coil 4 are connected here to improve the assemblability. Although not shown, the exciting coil 4 is formed by winding a conductor wire having an insulating coating on a bobbin having electrical insulation many times. The bobbin is made of a material having a small thermal resistance so that heat generated by the exciting coil 4 can be easily transmitted to the rotor, for example, an organic resin such as an epoxy resin in which aluminum oxide powder is dispersed and improved in thermal conductivity, iron, or the like. A composite material in which an insulating paint or resin is coated on the surface of the metal described above is preferable.

Centrifugal fans 15, 1 are provided on both end faces of the rotor 1.
6 are provided. The front bracket 10 and the rear bracket 11 have openings 10a, 10b, 11a, 11b at locations communicating with the suction side and the discharge side of the fans 15, 16, respectively.
Is open. The fan 15 sends the cooling air to the opening 1.
After sucking in from 0a and ventilating the inside of the front bracket, it is discharged from the opening 10b. Further, the fan 16 sucks the cooling air from the opening 11a and ventilates the inside of the rear bracket, and then discharges the opening 11 by dripping. Rear bracket 1
On the first side, the suction side and the discharge side of the fan 16 are structurally divided by a fan guide 33, and the fan guide 3
The openings 11a and 11b are located on both sides of the opening 3. It is desirable that the ventilation area formed by the brackets 10 and 11 and the fan guide 33 be as large as possible so as not to cause ventilation resistance of the fan. The arrows in the figure indicate the flow of wind by the fans 15 and 16.

The stator 40 has a stator coil 31 embedded in a slot provided in a stator core 8 made of laminated steel plates. The number of slots is three times the number of poles because three-phase alternating current is generated. The stator coil 31 is formed by winding a large number of insulated conductors, and in the slot, an insulating sheet is sandwiched between the stator coil 8 and the stator core 8 to provide insulation that also serves to protect the insulation of the conductor. The insulated wire is
A square line is desirable in order to increase the conductor line occupancy of the slot. However, round wire is easier to manufacture and wind. In any case, the voids in the slots are impregnated with varnish, resin or the like to fix the conductors together and to facilitate the heat generated by the coils to the stator 8. The stator core 8 is sandwiched between the front bracket 10 and the rear bracket 11, and is firmly fixed with through bolts (not shown).

The rotating shaft 6 has bearings 1 on both sides thereof.
The front bracket 10 and the rear bracket 11 are rotatably supported through the bracket 8. A pulley 1 for transmitting power from the engine is provided at the front bracket side end of the rotating shaft 6.
2 are provided. The front bracket 10 and the rear bracket 11 are provided with support legs 10c and 11d for fixing the vehicle alternator main body to the engine. The rear bracket 11 is provided with a voltage regulator 3 for adjusting the current to the exciting coil 4 and keeping the generated voltage constant regardless of the rotation speed.
0 and a rectifier 35 for converting an alternating current generated by the stator coil 31 to a direct current are fixed.

The rectifier 35 includes a diode 32, a diode minus cooling plate 21 and a diode plus cooling plate 22 to which the diode 32 is attached, and an insulating sheet (not shown) disposed between the cooling plates 21 and 22. )
, A molded terminal 23, a cooling member 25, and a fixing member 24 for fixing these to the rear bracket 11. Specifically, the diode minus cooling plate 21, the insulating sheet, the diode plus cooling plate 22, the mold terminal 23, and the cooling member 25 are arranged from the inner surface of the rear bracket 11.
These are arranged in a stacked state in this order, and a through hole communicating with them is provided so that the fixing member 24 penetrates from the cooling member 25 side. To the rear bracket 11,
The rectifier 35 is fixed to the rear bracket 11 by pressing the cooling member 25 toward the rear bracket 11.

The diode minus cooling plate 21 is made of a member having good heat conductivity, has a plurality of diodes 32 attached to the surface on the side opposite to the rear bracket 11, and has heat conductive grease between the rear bracket 11 and the like. To reduce the thermal resistance between them, and are thermally connected to the rear bracket 11. Thereby, the heat generated in the diode 32 is
The heat is transmitted to the rear bracket 11 and is radiated from the rear bracket 11.

The diode plus cooling plate 22 is made of a member having good heat conduction. A plurality of diodes 32 are mounted on the surface on the opposite side of the rear bracket 11, and an insulating member is provided between the diode and the cooling plate 21. It is arranged via a molded terminal 23 between the constituent insulating sheet and the cooling member 25, and is electrically insulated and thermally connected thereto.

The insulating sheet sandwiched between the diode minus cooling plate 21 and the diode plus cooling plate 22
It is desirable to protrude outward from both cooling plates 21 and 22 to maintain the insulation distance between the positive and negative electrodes. This insulating sheet has a high thermal conductivity in order to reduce the thermal resistance from the diode minus cooling plate 21 to the diode plus cooling plate 22. As a result, part of the heat generated by the diode 32 attached to the diode plus cooling plate 22 is transmitted from the diode plus cooling plate 22 to the diode minus cooling plate 21 via the insulating sheet, and further transmitted to the rear bracket 11. Bracket 1 after being told
Radiated from 1

Diode plus cooling plate 22 and cooling member 2
5, the molded terminal 23 is for fixing the diode terminal and the stator coil lead-out part.
It is composed of an electrically insulating member. If possible, a member having good heat conduction is desirable. Thereby, the cooling member 25 and the fixed member 24 are connected to the diode plus cooling plate 2.
2 are electrically insulated.

The cooling member 25 is made of a member having good heat conduction, is provided so as to be thermally connected to the diode plus cooling plate 22, and is provided in the air passage of the fan 16, and is provided with the diode plus cooling member. It has a size protruding outward from the plate 22 and a large surface area. Specifically, the cooling member 25 is made of aluminum, and includes a flat plate portion 25a that contacts the molded terminal 23 and a plurality of fins 25b that protrude from the flat plate portion 25a, as is apparent from FIG. I have. The ventilation path where the cooling member 25 is disposed has a small air ventilation area. If the number of fins of the cooling member 25 is too large, the ventilation resistance becomes too large. Therefore, the cooling member is balanced with the ventilation resistance and the cooling performance. It is necessary to determine 25 heat transfer areas. Note that a through hole 26 for passing the fixing member 24 is formed in the flat plate portion 25a.

With this configuration, part of the heat generated by the diode 32 attached to the diode-plus cooling plate 22 is transmitted from the diode-plus cooling plate 22 to the cooling member 25, and is radiated into the air passed by the fan 16. Is done.

The fixing member 24 is made of a member having good heat conduction. One end of the fixing member 24 is in close contact with the cooling member 25 and is thermally connected thereto.
1 to be thermally connected. It is preferable to use a thermally conductive grease in order to improve the thermal contact between the two. Part of the heat generated by the diode 32 attached to the diode plus cooling plate 22 is transferred from the diode plus cooling plate 22 to the cooling member 2 via the mold terminal 23.
5 and further transmitted from the cooling member 25 to the rear bracket 11 and radiated from the rear bracket 11.

Next, a modification of the cooling member 25 will be described with reference to FIG. The cooling member 25 of this modified example is a simple flat aluminum plate, and is used when there is not enough room in the gap between the molded terminal 23 and the fan guide 33. By flowing the cooling air as indicated by the arrow in FIG. 4, a high cooling effect can be obtained with almost no increase in ventilation resistance.
In this case, if the cooling member 25 and the fan guide 33 are too close to each other, the ventilation resistance increases. The cooling member 25 shown in FIGS. 3 and 4 is an example, and it is desirable to set the shape according to the space in which the cooling member 25 is mounted.

According to the embodiment described above, the fan 1
Since the cooling member 25 which is located in the ventilation passage 6 and is thermally connected to the diode plus cooling plate 22 is provided, the heat generated by the diode 32 attached to the diode plus cooling plate 22 is transmitted to the cooling member 25. The heat can be radiated from the cooling member 25 into the air flowing through the ventilation path, and the reliability of the diode 32 can be ensured with a simple configuration.
As a result, it is possible to provide an automotive alternator that can achieve both high output and mass productivity.

Further, the cooling member 25 is thermally connected to the diode plus cooling plate 22 while maintaining electrical insulation, and the cooling member 25 is thermally connected to the fixing member 24, and the fixing member 24 is electrically conductive. Since it is a good member and is thermally connected to and fixed to the rear bracket 11, the heat generated by the diode 32 attached to the diode plus cooling plate 22 is transmitted to the fixing member 24, and further, the fixing member 2
4 to the rear bracket 11 to radiate heat from the rear bracket 11. Accordingly, the diode 32 can be cooled without increasing the number of components.

Further, since the mold terminal 23 having good heat conduction and electrical insulation is interposed between the cooling member 25 and the diode plus cooling plate 22, there is no need to separately provide an electrical insulation member. With a simple configuration, the cooling performance of the diode 32 can be improved while ensuring electrical insulation.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a sectional view of a main part of an automotive alternator according to a second embodiment of the present invention. This embodiment is different from the first embodiment as described below, and the other points are basically the same as the first embodiment.

In this embodiment, an insulating member 27 is formed in a cylindrical shape at a portion where the fixing member 24 penetrates, and a gap is provided between the diode minus cooling plate 21 and the diode plus cooling plate 22. Since the cooling air flows through this space, the diode minus cooling plate 21 and the diode plus cooling plate 22 can be directly cooled. In particular,
Since there is no obstruction to cooling and ventilation such as the mold terminal 23 on this surface, cooling can be performed effectively. In addition, it is desirable to provide a gap of about 2 mm or more from the viewpoint of ventilation resistance.

As described above, the diode minus the cooling plate 2
1 and the diode plus cooling plate 22 are directly cooled by the cooling air, so that the diode minus cooling plate 21 is cooled.
And the diode 32 attached to the diode plus cooling plate 22 can be reliably cooled, and the reliability of the diode 32 can be secured with a simple configuration. As a result, it is possible to provide an automotive alternator that can achieve both high output and mass productivity.

Although the cooling member is not shown in FIG. 5, if the clearance between the mold terminal 23 and the fan guide 33 still has room even when the cylindrical insulating member 27 of this embodiment is provided, FIG. The cooling performance can be further improved by providing the cooling member 25 shown in FIG.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a sectional view of a main part of an automotive alternator according to a third embodiment of the present invention. This embodiment is different from the first embodiment as described below, and the other points are basically the same as the first embodiment.

In this embodiment, the diode minus the cooling plate 2
A cylindrical spacer 36 through which the fixing member 24 penetrates is provided between the first bracket 1 and the rear bracket 11 so that the diode minus the cooling plate 2
Since the gap between the first bracket 11 and the rear bracket 11 is formed to be a ventilation path for the fan 16, the diode minus cooling plate 21 can be directly cooled by the cooling air flowing through this gap. In particular, an opening 11 is formed in a portion of the rear bracket 11 facing the diode minus cooling plate 21.
By providing c, the cooling air can be more effectively taken in and the diode minus cooling plate 21 can be cooled. Thus, with a simple configuration, the reliability of the diode 32 can be secured, and a vehicular AC generator that can achieve both high output and mass productivity can be provided.

[0036]

As described above, according to the present invention,
With a simple configuration, the reliability of the diode is ensured by greatly improving the cooling performance against the heat of the diode,
An AC generator for a vehicle that can achieve both high output and mass productivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an automotive alternator according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of a state in which a cooling member of a rectifier section of the automotive alternator of FIG. 1 is omitted.

FIG. 3 is a sectional perspective view of a cooling member used in the vehicle alternator of FIG. 1;

FIG. 4 is a sectional perspective view showing a modification of the cooling member of FIG. 3;

FIG. 5 is a sectional view of a main part of an automotive alternator according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a main part of an automotive alternator according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotor, 2 ... Rotor claw, 4 ... Excitation coil, 6 ... Rotor shaft, 8 ... Stator core, 9 ... Brush ring, 10 ... Front bracket, 10a, 10b ... Opening, 11 ... Rear bracket, 11a, 11b, 11c: Opening, 12: Pulley, 15, 16: Fan, 18: Bearing, 21: Diode minus cooling plate, 22: Diode plus cooling plate, 23: Mold terminal, 24: Fixing member, 25: Cooling Member, 26: Through-hole, 27: Insulating member, 30: Voltage regulator, 31: Stator coil, 32: Diode, 33: Fan guide, 34: Brush, 35: Rectifier, 36: Cylindrical spacer, 40 …stator.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keizo Kawamura 502 Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. (72) Susumu Sasaki 2520 Takada, Hitachinaka-shi, Ibaraki Hitachi, Ltd. (72) Inventor Makoto Hirama 2477 Takaba, Hitachinaka-shi, Ibaraki F-term in Hitachi Car Engineering Co., Ltd.F-term (reference) PP32

Claims (5)

[Claims] A rotating shaft to which torque is transmitted from a vehicle engine via a pulley; a rotor fixed to the rotating shaft and excited by an exciting coil; and a rotor disposed outside the rotor. A stator on which a stator coil is wound, a front bracket for supporting the stator from a pulley side, supporting the rotary shaft via a bearing, and supporting the stator from a side opposite to the pulley; A rear bracket that supports the rotating shaft via a diode, a diode minus cooling plate to which the minus output side diodes of the plurality of vehicle alternators are fixed, and a diode plus to which the plus output side diodes of the plurality of vehicle alternators are fixed. A cooling plate, an insulating member for electrically insulating between the diode minus cooling plate and the diode plus cooling plate, and the diode arranged in order from the rear bracket side In a vehicle AC generator including a cooling member, a fixing member for fixing the insulating member and the diode-plus cooling plate to a rear bracket, and a fan that ventilates the bracket, the alternator is located in a ventilation path of the fan. And a cooling member thermally connected to the diode plus cooling plate. 2. The vehicle alternator according to claim 1, wherein said cooling member is thermally connected to said diode plus cooling plate while maintaining electrical insulation, and said cooling member is connected to said fixing member. An alternating current generator for a vehicle, wherein the alternator is thermally connected, the fixing member is a member having good thermal conductivity, and is thermally connected and fixed to the rear bracket. 3. A vehicular alternator according to claim 2, wherein a molded terminal having good heat conduction and electrical insulation is interposed between said cooling member and said diode plus cooling plate. Characteristic alternator for vehicles. 4. A rotating shaft to which torque is transmitted from a vehicle engine via a pulley, a rotor fixed to the rotating shaft and excited by an exciting coil, and arranged outside the rotor. A stator on which a stator coil is wound, a front bracket for supporting the stator from a pulley side, supporting the rotary shaft via a bearing, and supporting the stator from a side opposite to the pulley; A rear bracket that supports the rotating shaft via a diode, a diode minus cooling plate to which the minus output side diodes of the plurality of vehicle alternators are fixed, and a diode plus to which the plus output side diodes of the plurality of vehicle alternators are fixed. A cooling plate, an insulating member for electrically insulating between the diode minus cooling plate and the diode plus cooling plate, and In a vehicle alternator comprising an auto minus cooling plate, a fixing member for fixing the insulating member and the diode plus cooling plate to the rear bracket, and a fan that ventilates the bracket, the insulating member may be provided with the fixing member. An AC generator for a vehicle, characterized in that it is formed in a cylindrical shape at a portion through which the diode penetrates to form a gap between the diode minus cooling plate and the diode plus cooling plate. 5. A rotating shaft to which torque is transmitted from a vehicle engine via a pulley, a rotor fixed to the rotating shaft and excited by an exciting coil, and disposed outside the rotor. A stator on which a stator coil is wound, a front bracket for supporting the stator from a pulley side, supporting the rotary shaft via a bearing, and supporting the stator from a side opposite to the pulley; A rear bracket that supports the rotating shaft via a diode, a diode minus cooling plate to which the minus output side diodes of the plurality of vehicle alternators are fixed, and a diode plus to which the plus output side diodes of the plurality of vehicle alternators are fixed. A cooling plate, an insulating member for electrically insulating between the diode minus cooling plate and the diode plus cooling plate, and An automotive alternator including an auto minus cooling plate, a fixing member for fixing the insulating member and the diode plus cooling plate to the rear bracket, and a fan that ventilates the inside of the bracket. An alternator for a vehicle, wherein a cylindrical spacer through which the fixing member penetrates is provided between the rear bracket and the rear bracket to form a gap between the diode minus cooling plate and the rear bracket.