JPH0678504A - Ac generator for vehicle - Google Patents

Abstract

PURPOSE:To suppress a temperature rise of diodes in an AC generator for a vehicle by interposing a ring-shaped heat insulating material between a stator core and a rear bracket. CONSTITUTION:In a generator, a rotating magnetic field traverses a stator coil 5 (5a, 5b), so that it is electromagnetically induced to generate AC voltage. Next, an AC output generated in the stator coil 5 is connected to a connection terminal 20, buried in a diode terminal block 21, through a stator coil output wire 27, to flow an output current in diode elements 22, 23 full-wave rectified. In a conduction part, a temperature rise is generated by heating due to electrification, but the stator coil 5 is directly cooled by cooling air generated by rotating a fan, in addition, to diffuse heat to a stator core 4 further radiated to a front bracket 1. However, since a ring-shaped heat insulating material 3 is provided between the stator core 4 and a rear bracket 2 radiation from the stator core 4 to the rear bracket 2 is impeded, to suppress a temperature rise of diodes in low level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC generator mounted on a vehicle or the like, and more particularly to a cooling structure for the generator.

[0002]

2. Description of the Related Art A conventional vehicle alternator has a structure in which a stator core and a rear bracket are directly fitted to each other as shown in Japanese Utility Model Publication No. 1-147666. Therefore, a part of the heat generated in the stator coil and the stator core due to the power generation is transferred to the rear bracket through the stator core by heat conduction, and the temperature of the rear bracket is increased. Further, a part of the heat is transferred to the rear bracket by radiation from the end of the stator coil, thereby raising the temperature of the rear bracket.

On the other hand, the rear bracket is provided with a diode bridge for rectifying generated alternating current into direct current and a regulator for controlling generated voltage.
In particular, since the heat generated from the diode due to the rectification is radiated to the rear bracket, the heat radiation is influenced by the heat transmitted from the stator core side. In the current technology, the heat resistance temperature of the diode and regulator is lower than that of the stator coil, so the vital point of the vehicle alternator is the diode and regulator. When the output is improved, especially the diode exceeds the guaranteed temperature. To do.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling structure for suppressing a temperature rise of a diode of a vehicle AC generator.

[0005]

The above object is to interpose a ring-shaped heat insulating material between the stator core and the rear bracket, and to provide a heat insulating material on the portion of the inner circumference of the rear bracket facing the end of the stator coil. This is accomplished by depositing a heat-reflective material through.

[0006]

With the above structure, the temperature of the diode can be kept lower than in the prior art because the heat from the stator core side is cut off from the rear bracket to which the diode and the regulator are attached.

[0007]

Embodiments of the present invention will be described with reference to FIGS. In FIG. 1, a pair of front bracket 1 and rear bracket 2 that form the outer shell of the generator are fixed by a plurality of bolts (not shown) via a ring-shaped heat insulating material 3 and a stator core 4 around which a three-phase stator coil 5 is wound. . Cylindrical bearing boxes projecting toward the inside of the generator are formed near the center of the side surfaces of the brackets 1 and 2, and bearings 7 and 8 are attached to the respective bearing boxes, and a shaft 9 is freely rotatable from these bearings. Supported by.

A pair of rotor cores 10 each having an even number of claw-shaped magnetic poles with a minute gap maintained on the inner peripheral side of the stator core.
Is fixed to the shaft 9 while holding the field coil 11 inside. A pulley 6 is fixed to the tip of the shaft. Cooling fans 12a and 12b are fixed to the side surfaces of the pair of rotor cores 10, respectively.
The axial ends of a and 12b respectively face the inner side surface of the bracket 1 and the side surface of the fan guide 16 with an appropriate gap.

The slip ring 1 is coaxial with the shaft 9.
3 is fixed, and the brush 14a slides on the ring. The brush 14 a is housed in the brush holder 14 and indirectly fixed to the bracket 2.

Along with the brush holder 14, a regulator 22 for controlling the output voltage to be constant and a diode bridge 15 for full-wave rectifying the output current of the stator coil 5 are arranged on the same plane.

The ring-shaped heat insulating material 3 is made of a synthetic resin having a high heat insulating property or a metal having a relatively low thermal conductivity such as titanium or ferritic stainless steel.
It is sandwiched between the stator core 4 and the rear bracket 2, and they are fixed by a plurality of bolts (not shown).

In the diode bridge 15, a plurality of diode elements for full-wave rectifying the output of the stator coil 5 are embedded (+) side diode cooling fins 18, (-).
It is composed of the side diode cooling fin 19, a thin insulating sheet 17 for insulating both cooling fins, and a diode terminal block 21, and one surface of the (-) diode cooling fin is closely attached to the rear bracket 2.

The operation of the generator having the above structure will be described below. A field current flows to the field coil 11 via the brush 14 and the slip ring 13, and at the same time, a driving force is transmitted to the pulley 6 by an engine (not shown) or the like, and a rotating magnetic field is generated when the rotor core 10 fixed to the shaft 9 rotates. To do. When the rotating magnetic field crosses the stator coil 5, the stator coil is electromagnetically induced and an alternating voltage is generated.

The AC output generated in the stator coil is fed to the diode terminal block 21 via the stator coil output line 27.
Is connected to the connection terminal 20 embedded in the connection terminal 20, and the output current flows into the diode elements 22 and 23 connected to the connection terminal 20 for full-wave rectification.

At this time, since the output voltage of the generator changes depending on the rotation speed, the regulator 22 appropriately interrupts the field current so that the output voltage is controlled to be constant.

At this time, the temperature of the current-carrying portion rises due to the heat generated by the current-carrying.

With respect to the cooling system for removing the generated heat, the fans 12a and 12b fixed to the side surface of the rotor core 10 rotate as the shaft 9 rotates, so that cooling air flows into the generator and is discharged. Fan 12a
Of the cooling air is introduced from the intake port 1a of the front bracket 1 to cool the outer wall of the front bearing 7, cool the side surface of the rotor core 10a and then cool the stator coil 5a on the front side, and exhaust the exhaust port 1b of the front bracket 1. More discharged.

By the rotation of the rear fan 12b,
Cooling air is introduced from the intake port 2a of the rear bracket 2,
After cooling the outer wall of the rear bracket and the rear bearing 8 to cool the diode bridge 15 and the regulator, the rear stator coil 5b is cooled after passing through the suction port 24 of the fan guide and then discharged from the exhaust port 2b of the rear bracket 2. To be done.

To describe the cooling of the diode bridge 15 in more detail, the heat generated in the (-) diode element 22 is diffused to the (-) cooling fin 19 and radiated to the rear bracket 2 with which one surface of the cooling fin is in contact.
The heat generated in the (+) diode element 23 is diffused to the (+) cooling fin, and then is conducted to the thin film insulating sheet 17 having excellent thermal conductivity and the (-) cooling fin, and radiated to the rear bracket. The heat radiated to the rear bracket is transferred to the cooling air generated by the rotation of the fan 12b.

As described above, the cooling of the stator coil is directly performed by the cooling air generated by the rotation of the fan, is diffused to the stator core, and is further radiated to the front bracket. However, since there is a ring-shaped heat insulating material between the stator core and the rear bracket, heat dissipation from the stator core to the rear bracket is blocked.

Therefore, the temperature of the rear bracket can be kept lower than in the prior art, and the heat radiation from the diode to the rear bracket can be promoted, so that the temperature rise of the diode can be kept low.

Next, another embodiment will be described with reference to FIGS. In FIG. 4, reference numeral 25 is a metal material such as titanium or ferritic stainless steel, and 26 is a non-metal material such as a synthetic resin having excellent heat insulating properties. As shown in FIGS. It has a structure in which a metal material is covered with a non-metal material. The surface where this ring-shaped heat insulating material contacts the stator core or the rear bracket is composed of both metal and non-metal parts, but this metal part should have the necessary dimensions as a strength member. They are arranged at appropriate intervals on the circumference.

If this non-metal material is made of a material having a vibration absorbing property in addition to a heat insulating property such as rubber, a vibration absorbing effect can be obtained.

Further, the non-metal portion may be replaced with a void, and the air in the void serves as a heat insulating material.

Next, the prevention of heat radiation from the stator coil to the rear bracket will be described with reference to FIG. Reference numeral 29 denotes a surface 28 that faces the stator coil on the inner circumference of the rear bracket.
A heat-insulating material adhered to the surface of which a heat-reflecting material 30, such as aluminum foil, is adhered. This has the effect of reflecting the heat radiation from the stator coil and suppressing the temperature rise of the rear bracket, as a result of which the heat dissipation from the diode to the rear bracket is promoted and the temperature rise of the diode can be kept low.

[0026]

According to the present invention, the stator core and the rear bracket can be insulated from each other, so that the influence of heat from the stator core on the rear bracket can be blocked. Furthermore, since it is possible to prevent heat radiation from the stator coil to the rear bracket, the temperature of the rear bracket can be lowered correspondingly, and as a result, heat dissipation to the rear bracket of the diode is promoted and the temperature rise of the diode can be suppressed to a low level. I can.

Further, by using a material having a vibration absorbing function such as rubber as the heat insulating material, it is possible to obtain a vibration damping effect.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of a generator that is an embodiment of the present invention.

FIG. 2 shows a partial cross-sectional view of a diode section.

FIG. 3 shows a front view of a ring-shaped heat insulating material.

FIG. 4 shows a cross-sectional view at EE in FIG.

FIG. 5 shows a view from B of FIG.

FIG. 6 is a partial sectional view showing a heat radiation prevention structure.

[Explanation of symbols]

1 ... Front bracket, 2 ... Rear bracket, 3 ... Ring-shaped heat insulating material, 4 ... Stator core, 5 ... Stator coil, 10 ... Rotor core, 15 ... Diode bridge, 1
6 ... Fan guide, 29 ... Insulating material, 30 ... Heat reflecting material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keigo Naoi, Keigo Naoi 2520, Takaba, Katsuta-shi, Ibaraki Hitachi, Ltd., Automotive Equipment Division (72) Yoshiaki Honda Honda, Inc. 2520, Takaba, Katsuta, Ibaraki Hitachi, Ltd. Mfg. Co., Ltd. Automotive Equipment Division (72) Inventor Toshikazu Usami 2520, Takaba, Katsuta-shi, Ibaraki Hitachi Ltd. Automotive Equipment Division, Hitachi, Ltd. (72) Kenji Ishihara Katsuta, Ibaraki Pref. Automotive Engineering Co., Ltd.

Claims (4)

[Claims] 1. A stator core around which a stator coil is wound, a front bracket and a rear bracket that support the stator core and a rotating shaft through bearings, respectively, and a diode and a voltage for AC rectification on the rear bracket side. An automotive alternator comprising a regulator for adjustment, characterized in that a ring-shaped heat insulating material is interposed between the stator core and the rear bracket. 2. The ring-shaped heat insulating material according to claim 1,
An alternator for vehicles, characterized by being made of non-metal, metal, or a composite material thereof. 3. The vehicle alternator according to claim 1, wherein a material having heat reflectivity is adhered to a portion of the inner peripheral surface of the rear bracket facing the stator coil via a heat insulating material. 4. The vehicle alternator according to claim 2, wherein the heat insulating material is made of a material having a vibration absorbing property such as rubber.