JP3561927B2 - AC generator for vehicles - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a cooling structure for a vehicle alternator .
[0002]
[Prior art]
JP equitable 4-24939 discloses to the present Applicant's application, a centrifugal fan provided at both ends of the rotor core, the cooling windows that blowoff cooling air are opened in the peripheral wall of the housing while cooling the coil end of the stator coil In the cooling structure, the temperature of the coil end is lowered by providing a cooling air blowing passage in the coil end in a direction parallel to the blowing direction of the centrifugal fan.
[0003]
[Problems to be solved by the invention]
However, forming a large number of air passages as described above in the coil end of the stator coil in a direction parallel to the blowing direction of the centrifugal fan as in the above-described prior art complicates the winding operation of the stator coil.
Further, providing a large number of air passages at the coil end causes the windings of the respective coils to extend around these air passages, thereby increasing the wire length of the stator coil and increasing the copper loss of the stator coil. .
[0004]
Furthermore, since the axial dimension of the coil end of the stator coil increases, there is a disadvantage that the cross-sectional area of the blow-out flow path between the end face of the coil end and the inner end face of the housing is reduced, and the cooling air flow is reduced. There is a concern that cooling may deteriorate in other parts.
Of course, although there is an increase in the amount of cooling air through the air passage, the fluid pressure loss in the air passage having a complicated shape inside the coil end is large, and it is not possible to compensate for the decrease in the amount of cooling air in the blow-out channel. It is necessary to increase the size of the housing in order to secure a required amount of cooling air.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle AC generator capable of favorably cooling a coil end of a stator coil while avoiding a decrease in cooling air volume and an increase in physique. And
[0006]
[Means for Solving the Problems]
An automotive alternator according to the present invention includes a housing having a cooling window opened on a peripheral wall, a stator coil wound around a stator core fixed to the housing, and a rotatable housing inside the stator core. And a fan fixed to the end face of the rotor core and located at the inner peripheral side of the cooling window and blowing at least a part of the cooling air in a centrifugal direction, and at least a part of the cooling air is In a vehicle alternator that blows out from a fan, passes through a blowout flow path between an inner end surface of the housing and a coil end of the stator coil, and flows into the cooling window,
An end surface of the coil end of the stator coil facing the blowout flow path has a step in the axial direction.
More specifically , the housing is formed by fastening a front frame and a rear frame to each other with a fastening bolt, and a thin portion around the through-hole for inserting the fastening bolt, which is formed through the front frame or the rear frame, is formed by the blowout. The coil end has a projecting portion projecting into the flow path, and the coil end has a groove extending radially at an angular position where the projecting portion exists.
In a preferred aspect, the axial length of the coil end from the end surface of the stator core at the angular position where the overhang portion exists to the end surface of the coil end is a, from the end surface of the stator core at the angular position where the overhang portion does not exist. When the axial length of the coil end up to the end face of the coil end is b, a / b is set to 0.7 to 0.8 .

[0007]
[Action and effect of the invention]
Cooling air (at least a part of) from the fan passes through a blowing flow path between the inner end face of the housing and the coil end of the stator coil, and is blown out of a cooling window opened in a peripheral wall of the housing.
The end face of the coil end of the stator coil facing the outlet flow path has a step in the axial direction.
[0008]
By doing so, it is possible to increase the contact area (radiation area) of the stator coil in contact with the cooling air while minimizing the reduction in the cross-sectional area of the blow-out channel.
Further, it is possible to avoid an increase in the wire length of the stator coil and an increase in the resistance loss as compared with the above-described conventional technology, and it is possible to secure a cooling air flow without increasing the physical size.
[0009]
Further, since it is not necessary to form an air passage having a complicated shape at the coil end as in the above-described prior art, the stator coil forming step becomes relatively easy.
[0010]
【Example】
FIG. 1 illustrates an automotive alternator according to an embodiment of the present invention.
First, the basic configuration of this generator will be briefly described.
A frame (housing in the present invention) 1 composed of a front frame 11 and a rear frame 12 is fastened by a plurality of fastening bolts 13, the frame 1 rotatably supports a rotating shaft 2, and a rotating shaft 2 A field core (rotor core in the present invention) 31 is fixed, and a field coil (rotor coil) 32 is wound around the field core 31. Field iron core 31 and field coil 32 constitute a rotor. An armature core (stator core according to the present invention) 33 is fixed to the inner peripheral surface of the frame 1 so as to surround the field core 31, and an armature coil (stator coil according to the present invention) 34 is wound around the armature core 33. Is equipped. The armature core 33 and the armature coil 34 constitute a stator.
[0011]
A cover 4 made of aluminum, resin, or the like is fixed so as to surround the rear end surface of the rear frame 12, and an electric component room S is formed between the rear frame 12 and the cover 4. A rectifying device 41, a brush 42, and a regulator 43 are accommodated in the electric component room S.
When the rotating shaft 2 is belt-driven by the engine (not shown) through the pulley 21 and energized by energizing the field coil 32, the three-phase AC voltage generated in the armature coil 34 is converted by the rectifier into a three-phase AC voltage. Wave rectification is performed and output.
[0012]
A mixed flow fan 5 and a centrifugal fan 6 are fixed to the rotating shaft 2 with a field iron core 31 interposed therebetween. The centrifugal fan 6 constitutes a fan referred to in the present invention.
On the peripheral wall of the front frame 11, a number of cooling windows w 'are opened in a line in the circumferential direction around the mixed flow fan 5, and on the peripheral wall of the rear frame 12, a number of cooling windows surrounding the centrifugal fan 6 are provided. w are opened in a line in the circumferential direction.
[0013]
The centrifugal component 100 of the wind generated by the mixed flow fan 5 is blown out from the cooling window w 'while cooling the coil end 34F on the front side of the stator coil 34, and the axial component 101 flows between the poles of the rotor core 31. It penetrates in the axial direction to reach the rear end face of the rotor core 31, is deflected in the centrifugal direction by the disk portion of the centrifugal fan 6, penetrates through the rear coil end 34 </ b> R of the stator coil 34, or It is blown out from the cooling window w while cooling the coil end 34R by flowing through a blowout flow path P described later along the surface and the end face.
[0014]
Most of the wind 102 generated by the centrifugal fan 6 blows out from the cooling window w in the centrifugal direction through the blowing flow path P between the end face of the rear coil end 34R of the stator coil 34 and the inner end face of the rear frame 12. Is done.
Hereinafter, the characteristic portions of the present embodiment will be described.
As shown in FIG. 1, the front frame 11 and the rear frame 12 are fastened by a plurality (four in this example) of fastening bolts 13, and the bottom surface of a nut 14 screwed to the fastening bolt 13 is a rear frame 12. , And strongly presses the seating surface 12x toward the front side.
[0015]
The seat surface 12x is formed near the cooling window w in order to reduce the outer diameter and the axial length of the rear frame 12 (hereinafter, referred to as axial length). Therefore, the cylindrical portion around the through-hole 12e for fitting the fastening bolt 13 through the rear frame 12 has the overhang portion 12b (see FIG. 3) that overhangs the above-mentioned blow-out flow path P, and eventually the blow-out flow The projecting portion 12b is formed on the road P at intervals of 90 degrees in the circumferential direction.
[0016]
In this embodiment, in consideration of the presence of the overhang portion 12b, as shown in FIG. 3, at the angular position where the overhang portion 12b exists, the shaft length a from the end face of the stator core 33 to the end face of the coil end 34R is conventionally set as shown in FIG. 4), the shaft length b from the end face of the stator core 33 to the end face of the coil end 34R is set to be longer than the shaft length a at the angular position where the overhang portion 12b does not exist.
[0017]
More specifically, as shown in FIG. 2, the coil end 34R has a groove 340 extending in the radial direction at an angular position where the overhang portion 12b exists. The circumferential dimension of the groove 340 is D, and the axial dimension is L.
This produces the following effects.
First, since the coil end 34R can protrude more in the axial direction than the conventional coil end (see FIG. 4), the cooling effect of the coil end 34R is improved. In addition, since the end face of the coil end 34R is uneven, the surface area increases, and the cooling effect is improved.
[0018]
Secondly, the coil end 34R nevertheless does not protrude axially rearward at the angular position where the overhang portion 12b exists, so that the coil end 34R does not contact the overhang portion 12b. .
Third, the cooling air 102 blown out from the centrifugal fan 6 in the centrifugal direction is blown out in the centrifugal direction and flows into the blow-out flow path P. However, despite the presence of the overhang portion 12b, the blow-out flow path P The required width can be provided in the axial direction over the entire circumference, and the cooling air 102 can be blown out smoothly.
[0019]
In order to provide the above-described unevenness on the coil end 34R, a stator coil provided with such unevenness in advance is fitted into each slot of the stator core 33 , or a stator coil not subjected to unevenness processing is inserted into each slot of the stator core 33. After fitting, the coil end 34R may be forcibly deformed.
(Modification) In the above embodiment, it is possible to increase the surface area of the coil end 34R while securing the blowing flow path P, and it is possible to reduce the temperature of the coil end 34R.
[0020]
However, if the axial dimension fb between the protruding end surface (convex end surface) of the coil end 34R and the inner end surface of the rear frame 12 is excessively reduced, the fluid resistance is reduced even if the outlet cross-sectional area of the groove 340 increases. Will increase.
This is because the blowout direction of the cooling air 102 blown out from the centrifugal fan 6 has a centrifugal direction component and a circumferential direction component. When the axial dimension fb is reduced, the fluid pressure loss with respect to the circumferential direction component of the cooling wind 102 increases. It is because it becomes.
[0021]
Therefore, in this embodiment, by setting the ratio a / b of the two axial lengths a and b to 0.7 to 0.8, it is possible to achieve both improvement of the cooling performance of the coil end 34R and suppression of a decrease in the amount of cooling air. I have .
[0022]
However, the outer diameter of the centrifugal fan 6 is 90.8 mm, the number of revolutions is 3500 rpm, the blowing temperature is about 150 ° C., and the f of the fan is 25.1 mm. It can be seen that the temperature of the stator coil decreases as the length a of the coil end 34R increases as long as the shaft length a of the coil end 34R is secured to some extent.
(Experiment 2)
Next, in the conventional alternator (see FIG. 4) used in Experiment 1, a conventional product in which the shaft length a of the coil end was 19 mm, a comparative example product in which the shaft length a of the conventional product was extended to 22 mm, and the above-described embodiment. FIG. 7 shows the results of an experiment with the example product at different rotation speeds.
[0023]
However, the shaft length a of the product of this embodiment is 19 mm, the shaft length b is 22 mm, L is 3 mm, D is 18 mm, and other conditions are the same as those of the conventional product.
From this experimental result, it is understood that the cooling effect of the coil end 34R of the product of the present embodiment is the most excellent.
(Experiment 3)
Next, regarding the product of the present example used in Experiment 2, the axial length b was fixed, and the step ba was variously changed by excavating the groove 340. Show the relationship.
[0024]
When the step ba was dug by 6 mm, the cooling air flow increased by 120 cm ³ / min, and the temperature of the stator coil 34 decreased by about 5 ° C.
For this reason, it is suitable that the step ba is about 2 to 6 mm, preferably 3 to 5 mm. Incidentally, f, L, and D in this case were the same as above.
(Example 2)
In the above embodiment, the groove 340 is formed straight in the centrifugal direction. The cooling air 102 is formed by being inclined in a circumferential direction that is close to the blowing direction of the cooling air 102 from the centrifugal fan 6. By doing so, the circumferential component of the cooling air 102 blown from the centrifugal fan 6 is not sharply bent in the centrifugal direction, and the fluid pressure loss can be further reduced. (Example 3)
Another embodiment will be described with reference to FIG.
[0025]
In this embodiment, the end face of the coil end 34F on the front side in FIG. 1 is also provided with irregularities in the axial direction. Accordingly, the coil end 34F has the groove 341 extending in the radial direction periodically in the circumferential direction.
The effect is essentially the same as in the first embodiment.
Note that, similarly to this embodiment, in the first embodiment, the groove 340 may be formed periodically in the circumferential direction irrespective of the overhang portion 12b.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an automotive alternator according to an embodiment.
FIG. 2 is a partially enlarged plan view of a rear coil end of the stator coil of FIG. 1;
FIG. 3 is a partially enlarged sectional view of a rear coil end of the stator coil of FIG. 2;
FIG. 4 is a partially enlarged sectional view of a rear coil end of a conventional stator coil.
FIG. 5 is a partially enlarged sectional view of a front coil end of the stator coil of FIG. 2;
FIG. 6 is a characteristic diagram showing a relationship between an axial length a and a stator coil temperature.
FIG. 7 is a characteristic diagram showing a relationship between a stator coil temperature and the like and a rotation speed of the product of the present embodiment.
FIG. 8 is a characteristic diagram showing a relationship between a step ba, a cooling air flow rate, and a stator coil temperature of the embodiment example of FIG. 1;
[Explanation of symbols]
6 is a centrifugal fan (fan in the present invention), 11 is a front frame (housing), 12 is a rear frame (housing), 31 is a field core (rotor core), 33 is an armature core (stator core), and 34 is a stator coil. , 34R are coil ends of the stator coil, w is a cooling window, P is a blow-out channel, and 340 is a groove (step).

Claims (2)

A housing having a cooling window opened in a peripheral wall, a stator coil wound around a stator core fixed to the housing, a rotor core rotatably held by the housing inside the stator core, and the cooling window A fan fixed to the end face of the rotor core positioned on the inner peripheral side and blowing at least a part of the cooling air in a centrifugal direction, and at least a part of the cooling air blown out of the fan and an inner end face of the housing. In the vehicle alternator, which flows into the cooling window through an outlet flow path between the coil ends of the stator coil,
An end face of the coil end of the stator coil facing the blowout channel has a step in an axial direction,
The housing is formed by fastening the front frame and the rear frame with fastening bolts,
A thin portion around the through-hole for fitting the fastening bolt, which is formed in the front frame or the rear frame, has a protruding portion that protrudes into the blowout channel,
The alternator for a vehicle, wherein the coil end has a groove extending in a radial direction at an angular position where the overhang portion exists. The vehicle alternator according to claim 1,
Wherein the axial length of the coil end from the end face of the stator core to the end surface of the coil end at the angular position overhang exists a, the coil end from the end face of the stator core in an angular position which does not exist the overhang portion A / b is set to 0.7 to 0.8, where b is the axial length of the coil end up to the end surface of the vehicle .

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