JP2001086668A - Alternator for car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the sixth harmonic component which produces the loudest magnetic sound by arranging portions of different permeability on the magnetic pole surfaces of a stator, in an AC generator for cars which has a rectifying circuit within for converting AC voltage into DC voltage. SOLUTION: Teeth and slots are arranged in a stator core 105, and stator coils 106 are wound in the slots of the recessions of the stator core 105 into three phases. When claw-shaped magnetic poles are rotated by drive of an engine and magnetized, three-phase induced voltages are generated in the stator coils 106. The teeth 121 and slots 122 are formed alternately in the stator core 105, and the inlet width S of each slot 122 is larger a little bit than the wire diameter of the stator coils 106 arranged in the slots. The width (m) of a groove portion formed in the center part of each tooth 121 is approximately the same as the inlet width S of each slot. Consequently, noise of an AC generator for cars is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternator for a vehicle, and more particularly to an alternator for a vehicle suitable as a power generator for an automobile.

[0002]

2. Description of the Related Art A conventional vehicle alternator is disclosed in Japanese Unexamined Patent Publication No.
As described in Japanese Patent Application Laid-Open No. 215288, there is disclosed an apparatus in which a chamfer is provided at an end of a claw-shaped magnetic pole to reduce magnetic noise.

[0003]

SUMMARY OF THE INVENTION In the above prior art, it is an object of the present invention to moderate the magnetic fluctuation of the claw magnetic pole to reduce the magnetic excitation force. However, it cannot be said that the rectification ripples due to the three-phase full-wave rectification and the sixth harmonic of the slot ripples, which are basically present, are sufficiently reduced.

An object of the present invention is to provide a low-noise automotive alternator in which the sixth harmonic component having the largest magnetic sound is reduced to reduce the noise of the automotive alternator. is there.

[0005]

In order to achieve the above object, according to the present invention, a groove is arranged on a surface of a stator pole facing a rotor, and the order of slot ripple is twelfth harmonic, which is twice the current order. As the wave, the magnitude of the sixth harmonic is reduced by shifting the order of the sixth harmonic of the rectifying ripple and the harmonic, thereby reducing the electromagnetic exciting force. Further, the chattering sound of the teeth is reduced by connecting and fixing the bottom surfaces of the grooves provided on the surfaces of the teeth using an electron beam or laser welding.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a longitudinal sectional view of an air-cooled vehicle alternator 1. First, the configuration will be described. The vehicle alternator 1 of the present embodiment includes two brackets,
This bracket includes a front bracket 103 disposed on the pulley 102 side and a rear bracket 104 opposite the pulley side.
Consists of A shaft 101 is supported at the center of both brackets via a pulley-side bearing and an anti-pulley-side bearing.
Is attached, and a slip ring 1 is attached to the other end.
10 is attached. The pulley 102 is connected to a pulley arranged on the output shaft of the engine via a belt,
It rotates in proportion to the engine speed. A brush 111 is slidably attached to the slip ring 110 and supplies a field current from the brush 111 to a field winding 107 described later. The field winding 107 is wound around a bobbin 123 made of a liquid crystal polymer or a high heat conductive PPS which is a good heat conductor. Further, a rotor (rotor) is attached to the center of the shaft 101. A pair of claw-shaped magnetic poles 108 having a claw shape are arranged on the outer periphery of the rotor, and two cooling fans 115 for cooling heat generated by the stator windings are provided on the axial surface. Be placed.

A yoke 116 is arranged at the center of the rotor, and a field winding 107
Is wound, and a slip ring 110 is
The claw-shaped magnetic pole 108
Is magnetized. As described above, the bobbin 123 of the field winding 107 is made of a good heat generating conductor, and the heat generated by the field winding 107 is transferred to the yoke 116 and the claw-shaped magnetic pole 1.
08 is easy to tell. The reason is that deterioration of cooling of the field winding 107 is improved by the permanent magnet 112 disposed between the claw magnetic poles, which will be described later. That is, when the permanent magnet 112 is not provided, the cooling wind easily passes through the surface of the field winding 107. However, the flow of the cooling wind is hindered by the permanent magnet entering between the claw magnetic poles. This is because heat is transmitted to the claw poles by heat conduction to promote cooling. A pair of claw-shaped magnetic poles 1
A permanent magnet 112 is arranged between the claw poles 08 and a permanent magnet cover 113 for preventing the permanent magnet 112 from jumping out is provided at the outermost periphery of the claw-shaped magnetic pole 108 of the rotor. A stator core 105 is disposed between the pulley-side front bracket 103 and the anti-pulley-side rear bracket 104, and the rotor is disposed on an inner peripheral side of the stator core 105. Further, the permanent magnet cover 113 disposed on the surface of the claw-shaped magnetic pole 108 is disposed at a slight distance (mechanical gap) from the inner peripheral surface of the stator core 105. The mechanical gap length (air gap length) is a predetermined interval required from the relationship of mechanical characteristics, and is generally about 0.3 to 0.5 mm.

The mechanical gap may be equal to the magnetic gap depending on the material of the permanent magnet cover 113. However, when a cover made of a non-magnetic material is used, the magnetic gap length is equal to the mechanical gap. It is larger than the length by the thickness of the nonmagnetic cover.

A tooth and a slot are arranged on the stator core 105, and a stator winding 106 is wound in three phases in a slot corresponding to a concave portion of the stator core 105. When the rotor 108 is rotated and magnetized, a three-phase induced voltage is generated in the stator winding 106. The stator core 105 is fixed between the front bracket 103 and the rear bracket 104 by a spigot.
A rectifier diode 109 constituting a rectifier circuit and an IC regulator 114 for adjusting a generated voltage are arranged inside the rear bracket 104 on the side opposite to the pulley.

These rectifier diodes 109 perform full-wave rectification on the three-phase AC voltage generated in the stator winding 106 and convert it to a DC voltage. The IC regulator 114 controls the field winding current so that the DC voltage rectified by the diode for charging the battery is maintained at a constant voltage of about 14.3 V.

The alternator 1 for a vehicle configured as described above.
When the pulley 102 is rotated by the driving of the engine, the shaft 101 rotates together with the slip ring 110 and the rotor, and the DC current from the brush 111 is supplied to the field winding 107 inside the rotor, thereby causing the field winding 107 to rotate. Line 107
Operate to form an N pole and an S pole for each magnetic pole of the claw-shaped magnetic pole 108. The magnetic flux generated by the field winding 107 exits from the claw portion of the N-pole claw-shaped magnetic pole 108, and forms a magnetic circuit that returns to the claw portion of the S-pole claw-shaped magnetic pole 108 through the stator core 105. When the magnetic flux of this magnetic circuit links the stator winding 106, a three-phase induced voltage is generated in the stator winding 106. The three-phase induced voltage is full-wave rectified by the rectifier diode 109 and converted into a DC voltage. At this time, it is well known that ripple occurs every 60 electrical degrees. The rectified DC voltage is about 14.
IC regulator 1 so as to have a constant voltage of about 3V
This is achieved by controlling the field winding current at 14. The polarity of the permanent magnet 112 disposed between the claw magnetic poles described above is
It is magnetized in a direction in which the claw magnetic pole faces the same pole, and is for increasing the effective magnetic flux passing through the stator winding 106. In the present embodiment, a neodymium magnet having high residual magnetic flux density and high coercive force and high heat resistance is used between the claw magnetic poles.

The stator winding 106 is formed by a method in which one continuous round enameled wire is wound in a required number of turns in a ring shape, transformed into a star shape according to the number of poles, and inserted into a slot. And is produced by a method excellent in mass productivity. For this reason, the enameled wire used is of a round shape so that there is no problem even if there is a slight distortion when wound in a ring shape. Further, in the present embodiment, a thick wire is arranged in the stator slot in order to reduce the resistance value of the stator winding 106, but a structure in which the slot entrance is narrowed in order to reduce the size of the slot ripple. Therefore, the number of parallel circuits of the stator windings is increased, and the diameter of the windings is configured to be approximately the same as the conventional one. Thus, the workability is improved by making the winding diameter the same as the conventional one.

Next, the grooves provided in the stator core 105 will be described with reference to FIG. In FIG. 2A, the stator core 105
In this configuration, the teeth 121 and the slots 122 are provided alternately, and the entrance width S of the slot 122 is slightly larger than the wire diameter of the stator winding 106 disposed in the slot. As the slot entrance width S is reduced, the slot ripple component is reduced, which is effective in reducing magnetic noise. However, if the slot entrance width S is reduced, not only does the insertion workability of the stator winding 106 deteriorate, but if it is made too small, insertion becomes impossible. For this reason, the width is currently about 1.0 to 2.5 mm. In the present invention, the slot entrance width S is set to about 1.5 mm, and the width m of the groove provided in the center of the teeth 121 is made substantially the same as the slot entrance width S. In addition, since the effect of the groove can be expected if the depth of the groove is about 2 to 5 times the gap length, the depth of the groove is set to 1 mm in this embodiment. In this way, by providing a portion of the teeth 121 with a portion having a large magnetic resistance similar to that of the slot entrance, in other words, a portion having a small magnetic permeability, the slot ripple frequency without a groove is doubled, and the rectifying ripple frequency and the rectifying ripple frequency are doubled. By preventing this, the generation of magnetic noise is suppressed. The rectification ripple described here refers to a voltage ripple cycle repeated every 60 degrees in electrical angle by three-phase full-wave rectification.

FIG. 2B illustrates the shape of the groove provided in the teeth 121. In FIG. 2A, the upper width m1 of the groove and the width of the lower part m2 of the groove are the same. However, when the slot entrance of the surface of the teeth 121 facing the rotor is chamfered, a newly provided groove is provided. Is such that the upper width m1 is wider than the lower width m2. The chamfer angle of the groove is substantially the same as the chamfer angle provided at the tooth slot entrance. That is, in FIG.
a 'and bb' are parallel, and cc 'and dd' are parallel. As described above, the chamfer angles of the teeth groove and the slot entrance are substantially the same, and the magnetic pole shape is made symmetric so that magnetic fluctuations are made uniform to reduce magnetic noise. If the chamfer angle is increased, the apparent gap length increases and the performance decreases, so it is desirable to determine the size in balance with the required performance. In the above description, measures to reduce magnetic noise were described.However, when the rotor actually rotates, wind noise is generated due to the unevenness of the slot entrance and the newly provided groove. In addition, the occurrence of wind noise can be reduced by filling the recesses with resin or the like. In addition, if the teeth are long, chatter noise at the tip of the teeth is likely to be generated, but if the bottom of the newly provided groove is connected and fixed by welding with an electron beam, laser, etc., this chatter noise will be generated There is an effect that can be suppressed.

FIG. 2 (c) shows a stator coil 1 in a slot.
This shows a state in which the slot entrance and the groove are closed with a filler 127 such as a resin after the insertion of No. 06. As shown in this figure, by making the stator surface flat without irregularities, there is an effect that wind noise can be reduced. FIG.
Has been described in the case where one groove is provided on the inner surface of the stator, but the same effect can be obtained by providing a plurality of grooves. In the case where a plurality of grooves are provided, the output characteristics slightly decrease because the apparent gap length increases.

FIG. 3 shows a structure in which a space is provided in a portion near the rotor of the teeth instead of the groove in FIG. 2, and achieves the same effect as the case where the groove shown in FIG. 2 is provided. In this case, a portion where a hole is formed as a space needs to be very close to the gap length, so that a connection portion between the space and the gap is 0.05 mm to 0.5 mm or less. Also in this case, it is better that the slot entrance width S and the outer diameter m of the hole provided for the space are almost the same or the space m is slightly larger. Although the space 126 shown in the figure is circular, it may be square or elliptical.

The rectification ripple is a voltage ripple cycle of full-wave rectification, and occurs every 60 degrees in electrical angle.

Further, the slot ripple cycle is also
The electric angle is 60 degrees in the 36 slots of the pole, and the same sixth harmonic component.

For this reason, only the sixth harmonic component is conspicuous among the harmonic components due to the respective ripples. That is, assuming that one rotation of the rotor is the primary rotation component, the 36th harmonic component is significantly conspicuous. In the present invention, the sixth harmonic of the slot ripple is provided as a groove in the center of the tooth, while the rectifying ripple is kept as it is, so that the harmonic number of the slot ripple is 12th order and the component per one rotation of the rotor is 72%. Next, the generation of magnetic noise is reduced by dispersing the order.

Next, a case where the present invention is applied to a vehicle AC generator having a water cooling structure according to a second embodiment will be described with reference to FIG. FIG. 4 is a longitudinal sectional view of the vehicle alternator 1. First, the configuration will be described. The automotive alternator 1 of the present embodiment includes two brackets on both sides of the housing. The brackets include a front bracket 103 arranged on the pulley 102 side and a rear bracket 104 on the opposite side of the pulley. Shaft 1 in the center of both brackets
Reference numeral 01 is supported via a pulley-side bearing and an anti-pulley-side bearing. A pulley 102 is attached to one end of the shaft 101, and a slip ring 110 is attached to the other end. The above-described pulley-side bearing has a bearing retainer provided on the front bracket 103 as a detent for the outer ring of the bearing. The pulley 102 is connected via a belt to a pulley disposed on the output shaft of the engine, and rotates in proportion to the rotation speed of the engine. A brush 111 is slidably attached to the slip ring 110, and the brush 111
Supplies a field current to a field winding 107 described later. The field winding 107 is wound around a bobbin 123 made of a liquid crystal polymer having good heat conduction or high heat conduction PPS. Further, a rotor (rotor) is attached to the center of the shaft 101. A pair of claw-shaped magnetic poles 108 having a claw shape are arranged on the outer periphery of the rotor. The yoke 116 has a field winding 107 at the center of the rotor.
Is wound, and a slip ring 110 is
The claw-shaped magnetic pole 108
Is magnetized. A permanent magnet 112 is arranged between the claw magnetic poles of the pair of claw-shaped magnetic poles 108, and a permanent magnet cover 113 for preventing the permanent magnet 112 from jumping out is arranged at the outermost periphery of the claw-shaped magnetic poles 108. This permanent magnet cover 1
Reference numeral 13 is made of a non-magnetic stainless steel having a thickness of about 0.3 to 0.5 mm. A housing 120 having a stator core 105 built therein is disposed between the pulley-side front bracket 103 and the anti-pulley-side rear bracket 104, and the inner surface of the stator core 105 has a claw-shaped magnetic pole 108 as a rotor. Are arranged at a slight distance (mechanical gap) from the permanent magnet cover 113 disposed at a distance.
This mechanical gap length is a predetermined interval required from the relationship of mechanical characteristics, and is generally 0.3 to 0.5.
mm. Therefore, when the thickness of the stainless steel permanent magnet cover is taken into account, the magnetic gap lengths are the sum of the respective magnetic gap lengths, and are 0.6 to 1.0 mm. Stator core 105
Are provided with teeth and slots. A stator winding 106 is wound in three phases in a slot portion corresponding to the concave portion of the stator core 105, and the claw-shaped magnetic pole 108 is rotated by driving the engine. When magnetized, the stator winding 1
At 06, a three-phase induced voltage is generated. The stator core 105 is fixed to the inside of the housing 120 by swallowing, and the stator windings 106 in the slots of the stator core 105 are fixed.
Is filled with a good heat conductor 119, and as a result, the stator core 105 and the stator winding 1
06 and the housing 115 are integrally molded with a good heat conductor 119 and are thermally connected.

The good heat conductor mentioned here is a silicon rubber type having a higher thermal conductivity than air, an epoxy resin having a high thermal conductivity, or the like. A water passage 117 through which the cooling water flows is formed in the housing 120. A rectifier diode 109 is provided on the side of the housing 120 opposite to the pulley.
Is also connected in series with the water channel 117 provided in the housing in the axial direction. A rear plate 118 is arranged to close the cooling water passage 117 of the rectifier diode 109, and the rectifier diode 109 is arranged on the rear plate 118. A seal member (not shown) for preventing water leakage is arranged between the housing 120 and the rear plate 118 to prevent water leakage. The rear plate 118 is fixed to the housing 120 using eight screws by a rear bracket 104 disposed outside the rear plate 118. Non-pulley side rear bracket 104
Inside the rectifier diode 1 that constitutes the full-wave rectifier circuit
The negative side of 09 is directly fixed to a rear plate 118 for sealing the cooling water channel 117, and the rectifying diode on the positive side is disposed on the negative side via an insulating paper. Further, an IC regulator 114 for adjusting the generated voltage is arranged such that the cooling surface is in contact with the rear bracket 104. These rectifier diodes 109
Converts the three-phase AC voltage generated in the stator winding 106 into a DC voltage by full-wave rectification. The IC regulator 114 controls the field winding current so that the DC voltage rectified by the diode for charging the battery is maintained at a constant voltage of about 14.3 V.

The alternator 1 for a vehicle configured as described above.
When the pulley 102 is rotated by the driving of the engine, the shaft 101 rotates together with the slip ring 110 and the rotor, and the DC current from the brush 111 is supplied to the field winding 107 inside the rotor, thereby causing the field winding 107 to rotate. Line 107
Operate to form an N pole and an S pole for each magnetic pole of the claw-shaped magnetic pole 108. The magnetic flux generated by the field winding 107 exits from the claw portion of the N-pole claw-shaped magnetic pole 108, and forms a magnetic circuit that returns to the claw portion of the S-pole claw-shaped magnetic pole 108 through the stator core 105. When the magnetic flux of this magnetic circuit links the stator winding 106, a three-phase induced voltage is generated in the stator winding 106. The three-phase induced voltage is full-wave rectified by the rectifier diode 109 and converted into a DC voltage. This is achieved by controlling the field winding current by the IC regulator 114 so that the rectified DC voltage becomes a constant voltage of about 14.3 V. The above-described permanent magnets 112 arranged between the claw magnetic poles are magnetized in a direction in which the same poles face each other between the claw magnetic poles, and are for increasing the effective magnetic flux passing through the stator winding 106. In this embodiment, since the water cooling is adopted as the cooling method, the cooling effect at a low speed is large. Therefore, a neodymium magnet having high heat resistance and a large residual magnetic flux density is used between the claw magnetic poles.

Next, cooling of heat generated by copper loss generated in the stator winding 106 will be described. As mentioned earlier,
The stator core 105 on which the stator windings 106 are arranged is fixed to the housing 120 by flicking, and has a structure in which heat is easily transmitted to the housing 120. Further, as described above, the heat radiation path of heat is made of a resin having high thermal conductivity so that the stator winding 106 and the inner surface of the housing 120 can be in thermal contact with each other in order to improve the heat radiation of the stator winding 106. Provided. A plurality of holes penetrate the outer periphery of the housing 120 in the axial direction, and the water passage is closed by the front bracket 103 and the rear plate 118 to form a water passage in a zigzag shape. The cooling water is configured to flow through a zigzag water channel between the housing 120 and the outer peripheral surface, and can be cooled from the outer peripheral surface of the stator core 105. Further, heat generated due to copper loss of the field winding 107 generated inside the rotor is radiated to the front bracket 103 and the housing 120 via the internal air.

As to the effect, the order of the magnetic sound generation can be dispersed by shifting the slot ripple component to the twelfth harmonic component as in the air cooler shown in FIG. It is intended to reduce noise.

The slot ripple frequency of the present invention can be increased by forming grooves on the tooth surface, but the number of slots per phase can be reduced from the current one to two per pole and the same can be applied to a 12 pole 72 slot shape. Has a significant effect.

According to the present invention, there is an effect of noise reduction by making the order of the rectified ripple and the order of the slot ripple which are the causes of the magnetic sound do not coincide with each other. Further, by filling the grooves provided on the teeth surface with resin, varnish, or the like, generation of wind noise can be prevented, and there is an effect of reducing magnetic noise and wind noise.

Although the description has been given of the case where the permanent magnet is arranged between the claw magnetic poles in the text, it is needless to say that the same effect can be obtained even when there is no permanent magnet between the claw magnetic poles.

[0028]

As described above, according to the present invention, there is an effect of reducing the noise of the vehicle alternator.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an air-cooled vehicle alternator.

FIG. 2 is an enlarged view of a tooth portion for explaining a groove provided at a tooth tip portion.

FIG. 3 is an enlarged view of a tooth part for explaining a space provided at a tooth tip part.

FIG. 4 is a longitudinal sectional view of an AC generator for a water-cooled vehicle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Alternator for vehicles, 101 ... Shaft, 102 ... Pulley, 103 ... Front bracket, 104 ... Rear bracket, 105 ... Stator core, 106 ... Stator winding, 1
07: field winding, 108: claw-shaped magnetic pole, 109: rectifier diode, 110: slip ring, 111: brush, 1
12: permanent magnet, 113: permanent magnet cover, 114: I
C regulator, 115 cooling fan, 116 yoke, 117 water channel, 118 rear plate, 119 good heat conductor, 120 housing, 121 teeth, 1
22 ... slot, 123 ... bobbin, 124 ... good heat conductor, 125 ... groove, 126 ... space, 127 ... filler.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Honda 2520 Oita Takaba, Hitachinaka-shi, Ibaraki Co., Ltd. Within the Hitachi, Ltd. Automotive Equipment Group (72) Inventor Masami Takano 2520 Oita-Koba, Hitachinaka-shi, Ibaraki Co., Ltd. (72) Inventor Atsushi Suzuki 502 Kandachi-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Kenichiro Matsubara 502-Kindachi-cho, Tsuchiura-shi, Ibaraki Hitachi, Ltd. F-term in the mechanical research laboratory (reference)

Claims (7)

[Claims] 1. A rotor comprising: a pair of opposed claw-shaped magnetic poles each having a plurality of claw portions formed at a tip portion; and a field winding for magnetizing the claw-shaped magnetic poles; And a stator having a stator winding that generates an AC voltage by the magnetization of the claw-shaped magnetic pole, and a rectifier circuit that converts the AC voltage into a DC voltage. In a vehicle alternator, at least one or more portions having different magnetic permeability are arranged on the magnetic pole surface of the stator. 2. The vehicle alternator according to claim 1, wherein a groove is arranged on a surface of a magnetic pole of the stator. 3. An alternator for a vehicle, wherein the groove according to claim 2 has a chamfer angle equal to a chamfer angle of a tooth end. 4. The vehicle alternator according to claim 1, wherein a closed space is arranged near the magnetic pole surface of the stator. 5. The alternator for a vehicle according to claim 2, wherein the width of the groove arranged on the surface of the stator is wider on the inlet side than on the bottom side. 6. An alternator for a vehicle, wherein the groove and the slot entrance according to claim 2 are made uneven by resin or the like. 7. An alternator for a vehicle, wherein the bottom of the groove according to claim 2 is joined by welding of an electron beam, a laser or the like.