JPH02283916A - Alternator for automobile - Google Patents

Abstract

PURPOSE:To prevent the temperature of a roller bearing from rising, by disposing a ceramic material having a low thermal conductivity between a rotary shaft onto which a rotor is fitted and the inner race of the roller bearing. CONSTITUTION:A rear bracket 1 and a front bracket 2 are coupled together by means of bolts 3 so as to form a casing. A roller bearing 4 attached to the rear bracket 1 and a roller bearing 5 attached to the front bracket 2 bear a rotary shaft 6. A ceramic material having a low thermal conductivity is disposed between the rotary shaft 6 for a rotor 7 in the casing and the inner races 4, 5 of the roller bearings 4, 5. Alternatively, the inner races of the roller bearings 4, 5 may be formed of a ceramic material. As a result, the temperature of the roller bearings may be prevented from rising, thereby it is possible to prolong the life of the roller bearings.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an alternator for an automobile.

[Prior Art] In a conventional automobile alternator, a normal steel rolling bearing is used as a bearing.

[Problem to be solved by the invention]

When ordinary steel rolling bearings are used in bearings, such as those used in conventional automobile alternators, the rolling bearings greatly increase the heat generated during operation, especially the heat generated by the rotor, due to heat conduction through the rotating shaft. Warm up. As a result, there are problems such as grease leakage, reduced grease life, and reduced rolling fatigue life due to reduced hardness of the bearing ring.

Additionally, components such as seals and cages of rolling bearings must be heat resistant.

This problem becomes even more pronounced when the alternator rotates at a higher speed to achieve higher output.

[Means to solve the problem]

In the automotive alternator according to the present invention, a ceramic material with low thermal conductivity is interposed between the rotating shaft to which the rotor is attached and the inner ring of the rolling bearing that supports the rotating shaft, and the intervening means includes: The inner ring of the rolling bearing that supports the rotating shaft to which the rotor is attached is made of ceramic, or the inner peripheral surface and both end surfaces of the inner ring of the rolling bearing are coated with ceramics, or the rotating shaft to which the rotor is attached is coated with ceramics. Either the outer surface is coated with ceramics.

[For production]

When the above-mentioned automatic alternator is operated, the heat generated in the rotor is transferred to the rolling bearing through the rotating shaft. The temperature rise of the rolling bearing is prevented by the ceramic layer on the circumferential surface and both end surfaces, or the ceramic layer on the outer circumferential surface of the rotating shaft.

〔Example〕

Embodiments of the invention will be described with reference to the drawings.

The drawings illustrate one type of automotive alternator.

Rear bracket 1 and front bracket 2 are connected by bolt 3
are integrally connected to form the casing. A rotating shaft 6 is rotatably supported by a rolling bearing 4 attached to the rear bracket 1 and a rolling bearing 5 attached to the front brackets 1 to 2, and a rotor 7 is mounted on the rotating shaft 6 within the casing. A pole 8 and a slip ring 9 are attached, and a fan lO and a pulley 11 are mounted on the side protruding from the front bracket 2.

On the inner surface of the casing, there is a stator 1 facing the rotor 7.
2, brushes 13 are attached to the slip rings 9, respectively.

Note that reference numerals 14, 15, and 16 indicate the rectifying element, rotor coil, and stator coil.

In the above automatic alternator, in the first embodiment, the inner rings 4a and 5a of the rolling bearings 4 and 5 are made of Ceraminox, and in the second embodiment, the inner rings 4a and 5a of the rolling bearings 4 and 5 are made of Ceraminox.
The inner circumferential surface and both end surfaces of a are coated with ceramics. This coating may be applied, for example, by thermal spraying, or by applying a baking treatment after applying adhesive-type or paint-type ceramics.

Similarly, in the third embodiment, the outer peripheral surface of the rotating shaft 6 is coated with ceramics.

Examples of ceramic materials include A120J, Zr
02, Si3N4, SiC, etc., but Al2O3 is actually suitable because of its ease of processing. Their thermal conductivity is much lower than steel.

The above-mentioned automatic alternator is operated by rotating a rotating shaft 6, that is, a rotor 7, through a pulley 11 by belt transmission. At that time, the heat generated especially in the rotor 7 is cooled down by the fan IO that rotates together with the rotor 7.
In the first embodiment, the remaining heat is conducted to the rolling bearings 4, 5 through the rotating shaft 6 by the ceramic inner rings 4a, 5a of the rolling bearings 4.5 themselves.
In the second embodiment, the inner ring 4a of the rolling bearing 4.5,
In the third embodiment, due to the ceramic layer 5a.

Each of these is blocked by the ceramic layer on the outer peripheral surface of the rotating shaft 6, and the temperature of the rolling bearing 4.5 is prevented from rising.

[Effects of the Invention] In the automotive alternator of the present invention, the heat generated during operation, especially the heat generated in the rotor, is transferred to the ceramic inner ring of the rolling bearing itself, the ceramic layer of the inner ring of the rolling bearing, or the outer peripheral surface of the rotating shaft. The ceramic layer prevents heat conduction to the rolling bearing via the rotating shaft, and prevents the temperature of the rolling bearing from rising. As a result, grease leaks,
This prevents a decrease in grease life and hardness of the bearing ring.

The life of rolling bearings is extended. Furthermore, since the temperature of the rolling bearing is prevented from rising, inexpensive components that are not heat resistant can be used as the seals, retainers, and other components of the rolling bearing.

[Brief explanation of drawings]

The drawing is a sectional view of an automotive alternator in an embodiment of the present invention. 1: Rear bracket 2: Front bracket 3: Bolt 4.5: Rolling bearing 4a, 5a: Domestic import 6゛Rotating shaft 9 Nisso ring 12, Stator 15 Rotor coil 7: Rotor 8: Pole 10: Fan 11: Pulley 13: Brush I4. Rectifying element 16: stator coil

Claims (4)

[Claims] (1) Automotive alternator in which a ceramic material with low thermal conductivity is interposed between the rotating shaft to which the rotor is attached and the inner ring of the rolling bearing that supports the rotating shaft. (2) An automotive alternator in which the inner ring of the rolling bearing that supports the rotating shaft to which the rotor is attached is made of ceramics with low thermal conductivity. (3) An automotive alternator in which the inner peripheral surface and both end surfaces of the inner ring of the rolling bearing that supports the rotating shaft to which the rotor is attached are coated with ceramics having low thermal conductivity. (4) An automotive alternator in which the outer circumferential surface of the rotating shaft, on which the rotor is attached and is supported by rolling bearings, is coated with ceramics with low thermal conductivity.