The present invention relates to an AC power generator which outputs AC voltage from a stator coil along with rotation of a rotor, and in particular, relates to a vehicular AC power generator that charges an on-vehicle battery and supplies power to an on-vehicle electric device.
In recent years, in vehicular AC power generators, engine noise has been reduced in accordance with social requests for reducing vehicle exterior noise and for the purpose of improving merchantability by improvement in vehicle interior silence. Along with this, noise from a fan of the vehicular AC power generator which rotates at comparatively high speed has become harsh. This fan noise is, for example, a sound caused when cooling air in the radial direction from the fan interferes with a coil end, a magnetic pole, and the like of a stator which are cooled by the cooling air, and a wind noise caused by rotation of the fan itself. For example, as shown in FIG. 19 in Patent Document 1, it is disclosed that a rotor has eight claw magnetic poles, blades of a fan are provided two by two on a pair of the claw magnetic poles positioned symmetrically with respect to the rotation axis, so as to contact therewith, and blades are provided one by one on the other claw magnetic poles so as to contact therewith.
Patent Document 1: Japanese Patent No. 3279258
Patent Document 2: Japanese Laid-Open Patent Publication No. 3-218241
Therefore, the interval between the two blades provided two by two in a contact manner is narrow, and the interval between the blades provided one by one is wider than the former interval. In such blade arrangement, the frequency of noise caused by the blades having a narrow interval and the frequency of noise caused by the blades having a wide interval are greatly different from each other, and if the frequency of noise caused by the blades having a wide interval coincides with the frequency of noise occurring from the claw magnetic poles, further great noise can occur.
In addition, since the two pairs of the blades having narrow intervals are located opposite to each other with respect to the rotation axis, change in the blade interval periodically occurs per 180 degrees, and thus there is a problem that noises occurring due to the periodicity are strengthened by each other and thereby increased, for example.
A vehicular AC power generator according to the present invention includes: a pole core housed inside a frame and having claw magnetic poles, the pole core being configured to rotate in synchronization with a rotary shaft; and a cooling fan fixed in an annular shape to the pole core. Cooling air introduced from outside by rotation of the cooling fan is caused to flow inside the frame so that the cooling air cools a stator winding and an AC output rectification element. The cooling fan has blade portions composed of a main plate and a plurality of blade standing from the main plate. The number of the blade portions is larger than the number of poles of the pole core. Two or more of the blade portions are in contact with an end surface of each of two or more of the claw magnetic poles that are adjacent to each other.
The vehicular AC power generator of the present invention can suppress deformation of the blade portions caused by rotation and can suppress increase in noise occurring from the fan.
In
The rotor 8 includes: a field winding 9 which generates a magnetic flux by exciting current flowing therethrough; and a pole core 10 which is provided so as to cover the field winding 9 and in which magnetic poles are formed by the magnetic flux. The stator 12 includes: a cylindrical stator core 13 and a stator winding 14 which is wound around the stator core 13 and causes alternating current by variation in the magnetic flux from the field winding 9 along with rotation of the rotor 8.
The stator 12 is provided so as to surround the rotor 8, with the stator core 13 held by the opening ends of the front bracket 2 and the rear bracket 3 from both sides in the axial direction.
The bearing 5 on the rear side is fixed via a folder 26 to a bearing mounting portion 25 provided to the rear bracket 3.
The blade 52 is joined to the main plate 51 at the base of the blade and stands orthogonally. As shown in a top view of the rear fan 11b in
Further, as shown in
Next, operation of the vehicular AC power generator 1 configured as described above will be described. It is noted that the vehicular AC power generator 1 operates as a six-phase AC power generator having sixteen poles and ninety-six slots, but the number of poles and the number of slots are not limited thereto.
In the vehicular AC power generator 1, current is supplied from a battery (not shown) to the field winding 9 of the rotor 8 via the brush 16 and the slip rings 15, whereby a magnetic flux is generated. By the magnetic flux, N poles and S poles are alternately formed along the circumferential direction at the outer circumferential surface of the pole core 10. Meanwhile, rotation torque of an engine is transmitted from an output shaft of the engine to the shaft 6 via a belt (not shown) and the pulley 7, whereby the rotor 8 is rotated. Thus, a rotating magnetic field is given to the stator winding 14 of the stator 12, whereby an electromotive force is generated in the stator winding 14. AC current generated by the electromotive force is rectified by the rectification device 30 to charge the battery or to be supplied to an on-vehicle electric load.
The fans 11a, 11b rotate in conjunction with the rotor 8. On the front side, cooling air is sucked into the front bracket 2 through a front air inlet 2a and flows to near the rotor 8 in the rotation-axis direction 18. There, the cooling air bends in the centrifugal direction by the front fan 11a, to be discharged through a front air outlet 2b. On the rear side, cooling air is sucked into the protection cover 40 through a suction port provided in the protection cover 40, flows through heat dissipation fins provided to a plus-side heat sink 31 and a minus-side heat sink 32, toward a rear air inlet 3a of the rear bracket 3, and then flows to near the rotor 8 in the direction opposite to the rotation-axis direction 18. There, the cooling air bends in the centrifugal direction by the rear fan 11b, to be discharged through a rear air outlet 3b.
A part of heat generated by the stator 12 is dissipated from a coil end 12a to the cooling air bent outward in the radial direction by the fans 11a, 11b and discharged through the front air outlet 2b and the rear air outlet 3b, and another part of the heat is transmitted to the front bracket 2 and the rear bracket 3 and then dissipated from plural front ribs 19 of the front air outlet 2b and plural rear ribs 20 to the cooling air, whereby the stator 12 is cooled. A plus-side rectification element and a minus-side rectification element of the rectification device 30 are cooled by the cooling air flowing through the heat dissipation fins provided to the plus-side heat sink 31 and the minus-side heat sink 32.
Here, the rear fan 11b and the pole core 10 according to the present invention will be described. The rotor 8 of the vehicular AC power generator 1 rotates at two to three times the rotation rate of the engine, and therefore often rotates at a high speed of 10000 rpm or more. By the high-speed rotation, a great centrifugal force is applied to each blade portion 56 including the blade 52, and if the centrifugal force exceeds an allowable stress of the material of the blades, the blade portion 56 deforms so as to move outward in the radial direction and toward the side opposite to the rotation-axis direction 18.
The above deformation of the blade portion 56 means that the height h of the blade 52 decreases. Thus, the flow amount of cooling air generated by the rear fan 11b decreases, so that the temperatures of parts rise. In addition, each blade distal end 57 moves outward in the radial direction, and therefore there is a possibility that the blade distal end 57 collides with the coil end 12a or the stator core 13 of the stator 12 and thus they are broken.
In order to prevent such cooling performance reduction or breakage, it is necessary to suppress deformation of the blade portions 56 including the blades 52. The frequency of noise occurring from the pole core 10 is associated with the number of poles, and in the present configuration, the frequency is eight times the rotation rate. Therefore, if the number of the blades is eight, the noise having a frequency that is eight times the rotation rate is strengthened, so that the noise increases.
In order to suppress increase in noise and ensure the cooling air amount, it is necessary to provide a larger number of blades than the number of poles. However, in the case of using such a fan as to be manufactured by making cuts in a sheet metal and then performing a bending process, the main plate 51 joined to the base of the blade 52 is present on the opposite rotation-direction side and no main plate 51 is present on the rotation-direction side. Therefore, the circumferential-direction distance between the blade groove ends 54 of the adjacent blades is shortened, so that the blade portion 56 becomes more likely to deform.
In addition, as shown in
3, blade pitch numbers are assigned up to 13). In the narrow-pitch part 63, the adjacent pitches are slightly changed from each other. On the other hand, in the wide-pitch part 62, the average blade pitch is set to be 1.3 to 1.5 times the average blade pitch in the narrow-pitch part 63, and the pitches (in
However, in the above configuration, the circumferential-direction distance between the blade groove ends 54 of the blade portions 56 in the narrow-pitch part 63 is further shortened.
Accordingly, in order to suppress deformation of the blade portions 56, the blades 52 in the narrow-pitch part 63 are arranged such that, for example, the flat surface part of the end surface of one claw magnetic pole 60a is in contact with the two blade portions 56a, 56b, a side of the blade portion 56a that is close to the blade groove end 54a is in contact with the flat surface part of the end surface of the claw magnetic pole 60a, and the outer circumferential side of the blade portion 56a is located between the claw magnetic pole 60a and the adjacent magnetic pole 60b. The other one blade portion 56b is arranged such that the outer circumferential side of the blade portion 56b is in contact with the flat surface part of the end surface of the claw magnetic pole 60a, and a side of the blade portion 56b that is close to the blade groove end 54b is located between the claw magnetic pole 60a and the adjacent claw magnetic pole 60c. According to this configuration, one claw magnetic pole 60 and two blades 52 have such a positional relationship as to form one structural unit, and such structural units are arranged adjacent to each other in the part 63 where the pitches of the blades 52 are narrow, whereby deformation of the blades is suppressed and increase in noise is also suppressed.
Thus, in embodiment 1, owing to the above arrangement of the claw magnetic poles 60 and the blades 52, deformation of the blade portions caused by rotation can be suppressed, whereby reduction in cooling performance due to reduction of the air flow amount, and the like can be suppressed, and in addition, increase in noise occurring from the fan can be suppressed.
It is noted that, within the scope of the present invention, the above embodiments may be modified or simplified as appropriate. In the present embodiment, only the rear side has been mentioned, but also on the front side, by configuring the fan and the pole core in the same manner as in the present embodiment, the same effects such as noise reduction and suppression of deformation of the blade portions can be obtained.
1 vehicular AC power generator
2 front bracket
2
a front air inlet
2
b front air outlet
3 rear bracket
4 casing
5 bearing
6 shaft
7 pulley
8 rotor
9 field winding
10 pole core
11
a front fan
11
b rear fan
12 stator
13 stator core
14 stator winding
15 slip ring
16 brush
17 brush holder
18 rotation-axis direction
19 front rib
20 rear rib
22 voltage regulator
24 connector
25 bearing mounting portion
26 folder
30 rectification device
31 plus-side heat sink
32 minus-side heat sink
40 protection cover
51 main plate
52 blade
53 hole
54, 54a, 54b blade groove end
56, 56a, 56b blade portion
57 blade distal end
60, 60a, 60b, 60c claw magnetic pole
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2015/076078 | 9/15/2015 | WO | 00 |