GB2282709A

GB2282709A - A vehicular AC generator

Info

Publication number: GB2282709A
Application number: GB9410148A
Authority: GB
Inventors: Toshinori Tanaka; Yasuhiro Yoshida
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1993-10-06
Filing date: 1994-05-20
Publication date: 1995-04-12
Anticipated expiration: 2014-05-20
Also published as: JP2814890B2; GB2282709B; HK1002816A1; GB9410148D0; JPH07107704A

Abstract

A vehicular AC generator comprises a magnetic rotor 14, an excitation coil 10, a stator 3, and end brackets 1, 2 retaining the stator core and supporting the rotor shaft 5. Plural axial inlet openings 1a, 2a are provided in end faces of the brackets, and for plural outlet openings 1b, 2b are provided at outer peripheral faces of the brackets, for circulating cooling air, and fans 11, 12 are attached to end faces of the rotor pole core or cores 8, 9 for drawing cooling air through the inlet openings in the brackets. The outer configuration shape of the plurality of inlet openings 1a is non-circular. <IMAGE>

Description

A VEHICULAR AC GENERATOR The present invention relates to an alternating current generator which is used in an engine of a vehicle such as a motorcar.

Figure 5 is an axially sectional diagram showing a conventional three-phase vehicular AC generator which is shown, for instance, in Japanese Unexamined Patent Publication No. 7039/1991, and Figure 6 is a diagram viewing Figure 5 from the right hand side thereof.

In Figures 5 and 6, numeral 1 designates a front side bracket, numeral 2 designates a rear side bracket, and numeral 3 designates a stator which is composed of a stator core 3a and a stator coil 3b that is wound around the stator core 3a. Notations la and 2a designate pluralities of inlet openings respectively provided on end faces of the two brackets 1 and 2. A shape surrounding the plurality of inlet openings la or 2a (hereinafter, outer configuration shape) is circular (hatched portion in Figure 6). Notations lb and 2b designate pluralities of outlet openings respectively provided at outer peripheral portions of the two brackets 1 and 2. Numeral 4 designates a bolt which clamps the stator core 3a by fitting rims of openings of the two brackets 1 and 2 to outer peripheral end portions of the stator core 3a. Numeral 5 designates a shaft which is rotatably supported by the two brackets 1 and 2 through bearings 6 and 7 that are also supported by the two brackets 1 and 2. Numerals 8 and 9 designate magnetic pole cores which are fixed to the shaft 5 and which are disposed inside of the stator 3, and numeral 10 designates an excitation coil which is inserted into the inner peripheries of the magnetic pole cores 8 and 9.

Numerals 11 and 12 designate a pair of fans which are fixed to the respective end faces of the magnetic pole cores 8 and 9 and which are rotated concurrently with the rotation of the shaft 5. Numeral 13 designates slip rings attached to the shaft 5, and numeral 14 designates a rotor which is composed of the shaft 5, the magnetic pole cores 8 and 9, the excitation coil 10, the fans 11 and 12, and the slip rings 13.

Numeral 15 designates an electric collector for feeding electricity which incorporates inside thereof brushes 15a which abrasively contact the slip rings 13.

Numeral 16 designates a rectifier which converts an alternating current into a direct current by rectifying the alternating current that is induced in the stator coil 3b by feeding an excitation current from the brushes 15a to the excitation coil 10 through the slip rings 13 and by rotating the excitation coil 10 and the magnetic pole cores 8 and 9 by an engine (not shown) through a pulley 17. Notation 16a designates a heat sink for radiating heat that is generated at the rectifier 16.

Numeral 18 designates a voltage regulator which regulates a terminal voltage by detecting a generator voltage and by controlling the excitation current, and notation 18a designates a heat sink for the voltage regulator 18.

Next, an explanation will be given of the operation of the conventional alternating current generator.

Cooling air flows in the generator from the plurality of inlet openings la of the front side bracket 1 as shown by an arrow mark 19 by-rotating the fan 11, cools the bearing 6, the magnetic pole core 8, the excitation coil 10, the stator core 3a and the stator coil 3b, and is exhausted from the plurality of outlet openings lb to the outside. Similarly, cooling air flows in the generator from the plurality of inlet openings 2a of the rear side bracket 2 as shown by an arrow mark 20 by rotating the fan 12, cools the bearing 7, the voltage regulator 18, the rectifier 16, the magnetic pole core 9, the excitation coil 10, the stator core 3a and the stator coil 3b, and is exhausted to the outside from the plurality of outlet openings 2b.

In the conventional vehicular AC generator, the outer configuration shape of the plurality of the inlet openings la is circular as shown in Figure 6. Therefore, the order dispersion effect of a wind sound is not sufficient.

The order dispersion effect signifies that a high noise level in a comparatively narrow frequency range of a noise is converted and dispersed into that in a wider frequency range and a total noise level of a noise which is synthesized by respective frequency components, is lowered.

Therefore, sonic pressures of specified order components, for instance, 6-th order component, 12-th order component and the like are enhanced as shown in Figure 7, thereby generating an unpleasant sound.

Further, in another conventional generator, the order dispersion effect of a wind sound is not sufficient since the outer configuration shape of the plurality of inlet openings is circular. As shown in Figure 8, the sonic pressures of the 6-th order component, 12-th order component and the like are similarly enhanced and an unpleasant sound is generated.

It is an object of the present invention to resolve the above problems and to provide a vehicular AC generator which achieves the dispersion of the order components of a wind sound, reduces the wind sound and accordingly diminishes the unpleasant sound.

This is achieved by providing that the envelope bounding the plurality of inlet openings is non-circular.

According to one aspect of the present invention, there is provided a vehicular AC generator comprising: a rotor with a rotor shaft and excited by an excitation coil; a stator core surrounding the rotor; end brackets retaining the stator core and supporting the rotor; a plurality of inlet openings provided in an end face of at least one bracket in the axial direction of the bracket for intake of cooling air; a plurality of outlet openings provided in an outer peripheral face ofthe said at least one bracket for egress of cooling air; and at least one fan attached to an end face of the rotor or cores for drawing cooling air through the inlet openings; wherein the outer configuration shape of the said plurality of inlet openings is non-circular.

In a preferred arrangement the generator is a three-phase AC generator and the non-circular envelope is a polygon of which the number of angles is not a multiple of three, and is preferably equal to four.

According to another aspect of the present invention, there is provided a vehicular AC generator comprising: a magnetic pole core or cores fixed to a shaft and excited by an excitation coil; a stator core surrounding the magnetic pole core and attached with a stator coil; brackets retaining the stator core and supporting the shaft; pluralities of inlet openings provided at end faces of the brackets in the axial direction of the brackets for circulating cooling air; pluralities of outlet openings provided at outer peripheral faces of the brackets for circulating cooling air; and fans attached to end faces of the magnetic pole core or cores for introducing cooling air from the pluralities of inlet openings into the brackets; wherein an outer configuration shape of the pluralities of inlet openings is non-circular.

According to the present invention, the dispersion of the order components of a wind sound is achieved and the wind sound is reduced since the outer configuration shape of the pluralities of inlet openings is non-circular.

In the drawings: Figure 1 is a diagram viewing from an end face of a bracket and showing Example 1 of this invention; Figure 2 is an analytical diagram of wind sound frequencies in Example 1 of this invention; Figure 3 is a diagram viewing from an end face of a bracket and showing Example 3 of this invention; Figure 4 is an analytical diagram of wind sound frequencies in Example 3 of this invention; Figure 5 is an axially sectional diagram showing a conventional example; Figure 6 is a diagram viewing Figure 5 from the right hand side thereof; Figure 7 is an analytical diagram of wind sound frequencies in the conventional Example; and Figure 8 is an analytical diagram of wind sound frequencies in another conventional Example.

EXAMPLE 1 An explanation will be given of an example in reference to Figures 1 and 2. Figure 1 is a diagram viewing from an end face of a bracket, and Figure 2 is an analytical diagram of wind sound frequencies. A portion which is the same with or corresponding to one in the aforementioned conventional example, is attached with the same notation and the explanation will be omitted. In Figure 1, notation 1A designates a plurality of inlet openings which are provided at an end face of the front side bracket 1. As shown in Figure 1, the outer configuration shape of the plurality of inlet openings at the end face of the bracket (an outer configuration of the hatched portion in the drawing) is a quadrangle.

Further, the pole number of the alternating current generator is 12, the number of vanes of the front side fan is 10, and the number of vanes of the rear side fan is 14.

In this way, when the outer configuration shape of the plurality of inlet openings la is made quadrangular, in comparison with the data shown in Figure 7 for the plurality of inlet openings la having a circular outer configuration shape, the dispersion of the order components of a wind sound is achieved as shown in Figure 2, and therefore, the wind sound is diminished.

Further, the above explanation has been given to the plurality of inlet openings la of the front side bracket 1. However, a similar effect can naturally be provided with respect to the plurality of inlet openings 2a of the rear side bracket 2.

EXAMPLE 2 In the above Example 1, the outer configuration of the plurality of the inlet openings la is quadrangular.

However, a similar effect can be achieved when the outer configuration shape is a polygon, the number of angles of which excludes a multiple of 3, such as a pentagon, a heptagon, or an octagon. A polygon having the number of angles which is equal to a multiple of 3 such as a triangle is avoided to prevent the order components such as 6-th component, 9-th component, 12-th component or the like from being superposed and enhanced.

EXAMPLE 3 In this Example, a plurality of inlet openings 1B are provided with a rhombic outer configuration shape.

Figure 3 is a diagram viewing from an end face of a bracket, and Figure 4 is an analytical diagram of wind sound frequency. When the outer configuration shape of the plurality of inlet openings lb is a rhombus as shown in Figure 3, in comparison with the data shown in Figure 8, the order components such as 6-th component, 12-th component and the like are diminished as shown in Figure 4, and the sound pressure level of a total of components is lowered. Further, in this Example as in Example 1, the pole number is 12, the number of vanes of the front side one is 10, and the number of vanes of the rear side fan is 14.

As stated above, according to the present invention, the dispersion of the order components of a wind sound is achieved and the reduction of the wind sound and accordingly the reduction of an unpleasant sound is achieved by making the outer configuration of the plurality of inlet openings a non-circular shape.

Claims

CLAIMS:

1. A vehicular AC generator comprising: a rotor with a rotor shaft and excited by an excitation coil; a stator core surrounding the rotor; end brackets retaining the stator core and supporting the rotor; a plurality of inlet openings provided itl an end face of at least one bracket in the axial direction of the bracket for intake of cooling air; a plurality of outlet openings provided in an outer peripheral face of the said at least one bracket for egress of cooling air; and at least one fan attached to an end face ofthe rotor or cores for drawing cooling air through the inlet openings; wherein the outer configuration shape ofthe said plurality of inlet openings is non-circular.

2. A vehicular AC generator comprising: a magnetic pole core or cores fixed to a shaft and excited by an excitation coil; a stator core surrounding the magnetic pole core and attached with a stator coil; brackets retaining the stator core and supporting the shaft; pluralities of inlet openings provided at end faces ofthe brackets in the axial direction ofthe brackets for circulating cooling air; pluralities of outlet openings provided at outer peripheral faces of the brackets for circulating cooling air; and fans attached to end faces ofthe magnetic pole core or cores for introducing cooling air from the pluralities of inlet openings into the brackets; wherein an outer configuration shape ofthe pluralities of inlet openings is noncircular.

3. The vehicular AC generator according to Claim 2, wherein the vehicular AC generator is a three-phase alternating current generator and the outer configuration shape of the pluralities of inlet openings is polygonal wherein the number of angles of the outer configuration shape is not a multiple of three.

4. The vehicular AC generator according to Claim 3, wherein the outer configuration shape of the plurality of inlet openings is quadrangular.

5. A vehicular AC generator substantially as herein described with reference to figures 1 and 2 or figures 3 and 4 of the accompanying drawings.