GB2281818A

GB2281818A - Cooling fan for a vehicle alternator

Info

Publication number: GB2281818A
Application number: GB9324585A
Authority: GB
Inventors: Nam-Kook Kim; Yong-Tak Jeon; Hyo-Soo Jeon; Jin-Ho Park; Seong-Yup Yim
Original assignee: Mando Machinery Corp
Current assignee: Mando Machinery Corp
Priority date: 1993-09-06
Filing date: 1993-11-30
Publication date: 1995-03-15
Anticipated expiration: 2013-11-30
Also published as: JP2654618B2; FR2709888A1; GB2281818B; FR2709888B1; GB9324585D0; KR0118770B1; JPH07203659A; DE4401625A1; KR950010289A

Description

N AN ALTERNATOR WITH COOLING FAN FOR A VEHICLE The present invention

relates to an alternator with cooling fan for a motor vehicle. 5 Such alternators with fans are widely used in automobiles and other vehicles because of their capacity to be charged at low speed.

For example, an AC generator is disclosed in Japanese Patent Showa No. 57-95150 which has a ventilation unit equipped with front and rear brackets facing a shaft, a rectifier installed in one of the brackets, a stator mounted between the brackets, a rotating rotor installed on each bracket, and a cooling fan, located adjacent to the outer end face of the front bracket and rear bracket, fixed to the rotor. A centrifugal ventilation fan is mounted on the end of the semi-cooling fan of the rotor. A first air inlet opening for the inflow of cooled air is formed on the end of one of the brackets where the centrifugal fan is fixed, a second air outlet opening for discharging the cooled air is formed on the ventilation part of one of the brackets where the first air inlet opening is formed, a third air outlet opening for discharging the cooled air is formed on the shaft-directed end face of the remaining bracket, and a fourth air inlet opening for the inflow of the cooled air is formed in the ventilation unit of one of the brackets. The cooled air is sucked in through the first air inlet opening and discharged through the second air outlet opening as the centrifugal fan rotates. Some of the cooled air sucked in through the first air inlet opening is discharged out through the third air outlet opening after passing across the rotor and stator as the cooling fan rotates, and cooled'air sucked in through the fourth air inlet opening is discharged out through the third air outlet opening.

An alternator is also described in Japanese Patent Showa No. 57-95150 in which the second cooling fan blade is formed at an obtuse or acute angle relative to the side of the field core. This increases the amount of cooled air 5 inflow for better cooling efficiency.

The alternator described in Japanese Patent Showa No. 63-15652 has a cooling fan with arc shaped blades whose inner surfaces face the rotating shaft. The inner part of each blade is angled at ten degrees relative to a line extending from the shaft, and the outer part of each blade is angled at about 15 to 200 relative to a line extending from the shaft.

15. An alternator described in Japanese Patent Heisei No.

1-157251 has cooling fan blades formed at obtuse angles relative to the side of the field core. The number of blades is the same as that of the finger parts of the rotor pole.

Japanese Patent Heisei No. 59-178935 describes an alternator which has cooling fan blades formed at obtuse angles relative to the side of the field core.

United States Patent No. 4,549,103 discloses a vehicle alternator having a cooling fan secured to one end face of a rotor designed to produce radial and axial flows of cooling air. The radial air flow passes across a stator coil and outwardly through air outlet openings formed in a peripheral wall portion of a housing. The axial air flow passes through spaces between respective fingers of rotor core and also through an air gap between the rotor and stator, so that the rotor and stator coils are reliably cooled by the cooling fan. In an embodiment, an additional radial-flow fan is provided and mounted on the rotor-.in face-to-face contacting relationship with the other end face of the rotor.

It is an object of the present invention to provide a fan for a vehicle which has higher cooling efficiency than 5 the prior art mechanisms.

According to a first aspect of the present invention there is provided a fan for a vehicle comprising a rotor having a rotor shaft carrying a rotor, a stator having a stator core arranged coaxially with and surrounding said rotor and having at least one electrical supply wire electrically connected thereto, and a rotatable fa n supported by said rotor to be rotatable thereby, said rotatable fan having a generally planar part which extends substantially radially with respect to said rotor, wherein the fan comprises a plurality of blades extending at an angle to said generally planar part, and wherein, to enhance the cooling effect of the fan, each blade extends at an angle to said generally planar part which is greater than 60, and more than fourteen blades are provided.

Preferably, each said fan blade extends at an angle of substantially 700 to said generally planar part.

The angle of said blade makes it possible to include more than fourteen blades on the fan, for example sixteen or seventeen blades may be provided. This increases the cooling efficiency of the fan.

The present invention also extends to a fan for a vehicle comprising a rotor having a rotor shaft carrying a rotor, a stator having a stator core arranged coaxially with and surrounding said rotor and having at least one electrical supply wire electrically connected thereto, and a rotatable fan supported by said rotor to be rotatable thereby, said rotatable fan having a generally planar part which extends substantially radially with respect to said rotor, wherein the fan comprises a plurality of blades extending at an angle to said generally planar part, and wherein the rotor shaft is provided with a longitudinally extending groove which is aligned with a recess in the generally planar part of said fan and through which the or an electrical supply wire extends.

Preferably, a second said fan also having a generally planar part extending substantially radially to said rotor is provided, each of said fans being connected to a respective axial end of said rotor, and each said fan carrying a respective plurality of blades.

Embodiments of the present invention will hereinafter be described, by way of example, by reference to the accompanying drawings, in which:

Figure 1 is a cross sectional view of a conventional alternator, Figure 2 is a cross sectional view of a rotor assembly of the alternator of Figure 1, Figure 3 is a side view of the rotor assembly of Figure 2, Figure 4 shows a cross sectional view of an AC generator and fan of an embodiment of the present invention, Figure 5 is a cross sectional view of a rotor assembly of the fan of Figure 4, Figure 6 is a side view of a rotor assembly of the fan of Figures 4 and 5, Figures 7 and 8 are examples of comparative experiments between the conventional alternator and the fan of the embodiment of the present invention, and Figure 9 is a graph showing the air flow induced as a function of the blade angle.

In the drawings, the following references are used to identify features of the structure.

la, lb: Bracket, lc: Cover, 2: Stator Core, 2a:

Stator Coil, 3: Rotor, 3a: Rotor Shaft, 4a, 4b: Cooling Fans, 4b-1: Blade, 4b-2: Bending Unit, 4b-3: Plate Units, 4b-4: Rib Units, 5a: Front Bearing, 5b: Rear Bearing, 6: Rectifier, 6a: Heat Sink of the Rectifier, 6b: Terminal, 7: Brush Holder, 8: Pulley, 9: Bobbin, 10:

Field Coil, 10a: Protracting Wire of the Field Coil, 11: Slip Ring Stator Core, lla, llb: Slip Ring, 11c, lld: Terminal of the Slip Ring, 12a, 12b: Pole Core, 13: Field Core, 6: Outlet Angle.

The present invention relates to an AC generator and fan for a vehicle such as automobile. Generally, AC generators are widely used because of their capacity to be charged at low speed. Also, the electric capacity of the generator is not limited according to the rectifying condition.

A conventional alternator is illustrated in Figure 1 and comprises a rotor shaft 3a carrying a pulley 8 and rotor 3. A front bearing 5a is installed between the rotor shaft 3a and the pulley 8, and a rear bearing 5b is installed on the opposite side of the pulley 8. A steel cooling fan 4a, 4b is installed on both axial ends of the rotor 3. A stator core 2 surrounds the exterior of the rotor 3. A pair of brackets la, lb support the rotor 3 and the stator core 2. A rectifier is installed in the bracket lb, and a brush holder 7 is provided where a rectifier and voltage regulator are fixed.

As shown in Figure 2 where-a rotor of a conventional alternator is illustrated, the rotor 3 comprises a field core 13 on which a field coil 10 is wound, a pair of pole cores 12a, 12b, located on both ends of field core 13, and fixed to the field core 13 by the rotor shaft 3a, and a bobbin 9 that supports a protracted wire 10a of the field core. Furthermore, as illustrated in Figure 3, there are fourteen blades 4b-1 and two bending units 4b-2 on a cooling fan 4b. Each blade 4b-1 of the cooling fan is formed in such a way that it extends at an angle of 600 relative to the generally flat major section of the fan which extends substantially radially of the rotor shaft.

In the conventional alternator illustrated, the cooling fan 4b is mounted on one end face of the pole core 12b by a projection welding method after the protracted wire 10a of the field coil 10 is connected to terminals llc, lld of slip rings lla, llb. Therefore, to prevent the protracted wire 10a from being pressed and cut by plates 4b-3 when assembling the cooling fan 4b, bending unites are mounted on the cooling fan 4b so as to draw out the protracted wire 10a through a tunnel-type space formed by the bending units 4b-2 of the cooling fan 4b and one end face of the pole core 12b.

However, the conventional manufacturing method so far described has a number of shortcomings. Thus, when drawing out the protected wire 10a of the field coil 10 as described, the bending units 4b-2 must be mounted on the cooling fan 4b thereby making it necessary to go through a bending process, which is an extra manufacturing process, in order to install the cooling fan 4b. Also, when assembling the cooling fan 4b, the bending units 4b-2 of the cooling fan 4b must be aligned to the protracted wire 10a in order to prevent the protracting wire 10a from being cut by plate units 4b-3 of the cooling fan 4b. Moreover, the bending units 4b-2 of the cooling fan 4b experience deformation since they must be elongated as much as the bent length in order to prevent the blade 4b-1 from moving when being bent. Thus the thickness of the bending units 4b-2 becomes thinner than the thickness of plate units thereby reducing the strength of the cooling fan when the rotor accelerates or decelerates suddenly. Another weakness of the conventional manufacturing method is that the number of blades that can be installed is limited to fourteen.

Figure 4 is a cross sectional view of an embodiment of an alternator of the present invention and Figure 5 a cross sectional view illustrating its rotor. The alternator comprises a rotor shaft 3a carrying a pulley 8 and a rotor 3, a front bearing 5 installed between the rotor shaft 3a and the pulley 8, and a rear bearing 5b installed on the opposite side of the pulley 8. Steel cooling fans 4a and 4b are installed on opposite axial ends of the rotor 3. A stator core is provided and surrounds and protects the exterior of the rotor 3. The rotor shaft 3a also supports a pair of brackets la, 1b which support the rotor 3 and the stator core 2. A rectifier 6 is installed on the exterior of the bracket lb, as is a brush holder 7 with a voltage regulator. A synthetic resin cover lc covers the brush holder 7. The rotor 3 of the alternator of the embodiment of the invention is mounted on both ends of the field core on which a stator core 10 is wound and a field core 13 is made up of a pair of pole cores 12a, 12 that are fixed together with the field core 13 by the rotor shaft 3a. A pair of slip rings 11a, 11b are used to supply current to a field core 10 through a protracting wire 10a of the field coil 10. A bobbin 9 supports the protracting wire 10a when the protracting wire 10a is drawn out from the field coil

10. The path of the protracting wire 10a of the field coil on the cooling fan 4b is maintained as empty space with no installed structures. The shape of the cooling fan at this part is maintained by rib units 4b-4 installed on the circumference of the cooling fan.

The blades 4b-1 are each formed in such a way that it extends at an angle of substantially 70 relative to the generally flat major section of the cooling fan 4b. Consequently, the number of blades of the alternator of an embodiment of the present invention can be increased to fourteen or more, for example, to sixteen or seventeen blades.

In the illustrated embodiment, an alternator with sixteen blades is shown. In the alternator having the previously mentioned structure, the protracting wire 10a of the field coil 10 is drawn out to terminals llc, lld of the slip rings lla, llb along a groove on the rotor shaft 3a. The cooling fan 4b is assembled on one end face of the pole core 12b by front bearing 5a projection welding method before or after connecting the protracting wire 10a to terminals llc, lld. This is clearly illustrated in Figure 6. Accordingly, the cooling fan 4b, with its sixteen blades, induces the air flow that cools the rectifier or stator coil.

Also, structures such as plate units 4b-3 or bending units 4b-2 are not installed on the path of the protracting wire of the field coil 10 of the cooling fan unlike the case illustrated in Figure 3 where the structure of the conventional alternator is given. Therefore, the protracting wire 10a of the field coil 10 can not be cut by the plate units 4b-3 of the cooling fan. Moreover, the bending process can be omitted during manufacture of the cooling fan 4b and the assembling process can be carried Z1 out more easily. Furthermore, the strength of the cooling fan 4b is not decreased at all as the thickness of the bending units 4b-2 becomes thinner than the thickness of the plate units.

Finally, by angling each blade 4b-1 to 700 relative to the flat major section of the cooling fan, the number of blades 4b-1 of the cooling fan 4b that can be formed is increased from fourteen, for example, to sixteen. With the increased number of blades, the amount of air flow induced by the cooling fan while the rotor core 3 is being rotated is increased and as a result, the cooling capacity and durability of the alternator improves.

In Figures 7 and 8, the results of air flow measurement and temperature rising tests on each part of the alternator according to the number of rotating speeds of both the conventional cooling fan illustrated in Figure 3 and the cooling fan of the present invention is shown.

As shown in the graphs of Figures 7 and 8, the amount of air flow induced by the cooling fan of the present invention is about 5% higher than that of the conventional cooling fan when run at 500ORPM. Also, the cooling fan of the present invention is found to be capable of reducing the temperature of the stator coil about 5C more than the conventional one.

Figure 9 is a graph showing the change in the amount of air flow induced as the angle of each blade respective to the flat major section of the fan is varied while other parts of the cooling fan remain unchanged.

That is, Figure 9 illustrates that the amount of air flow induced reaches its maximum when the blade angle is set to 700. In addition, the cooling effect improves as the amount of air flow induced is increased.

Claims

A fan for a vehicle comprising a rotor having a rotor shaft carrying a rotor core, a stator having a stator core arranged coaxially with and surrounding said rotor and having at least one electrical supply wire electrically connected thereto, and a rotatable fan supported by said rotor to be rotatable thereby, said rotatable fan having a generally planar part which extends substantially radially with respect to said rotor, wherein the fan comprises a plurality of blades extending at an angle to said generally planar part, and wherein, to enhance the cooling effect of the fan, each blade extends at an angle to said generally planar part which is greater than 60% and more than fourteen blades are provided.
2. A fan as claimed in Claim 1, wherein each said fan blade extends at an angle of substantially 70 to said generally planar part.
3. A fan as claimed in Claim 1 or Claim 2, wherein the fan has sixteen blades.
4. A fan as claimed in Claim 1 or Claim 2, wherein the fan has seventeen blades.
5. A fan for a vehicle comprising a rotor having a rotor shaft carrying a rotor, a stator having a stator core arranged coaxially with and surrounding said rotor and having at least one electrical supply wire electrically connected thereto, and a rotatable fan supported by said rotor to be rotatable thereby, said rotatable fan having a generally planar part which extends substantially radially with respect to said rotor, wherein the fan comprises a plurality of blades extending at an angle to said generally planar part, and wherein the rotor shaft is provided with a longitudinally extending groove which is aligned with a recess in the generally planar part of said fan and through which the or an electrical supply wire extends.
6. A fan as claimed in Claim 5, wherein, to enhance the cooling effect of the fan, each blade extends at an angle to said generally planar part which is greater than 600, and more than fourteen blades are provided.
7. A fan as claimed in Claim 6, wherein each said fan blade extends at an angle of substantially 700 to said generally planar part.
8. A fan as claimed in Claim 6 or 7, wherein the fan has sixteen blades.
9. A fan as claimed in Claim 6 or 7, wherein the fan has seventeen blades.
10. A fan as claimed in any preceding claim, wherein a second said fan also having a generally planar part ' extending substantially radially to said rotor is provided, each of said fans being connected to a respective axial end of said rotor, and each said fan carrying a respective plurality of blades.
11. A fan as claimed in any preceding claim, wherein leaf units are provided circumferentially of the fan for maintaining its shape.
12. A vehicle alternator with an enhanced cooling mechanism whose sixteen blades are angled at 70 relative to the flat major section of the fan comprising, a rotor shaft having a pulley and a rotor from which a protracting wire is drawn out; and a front bearing installed between a rotor shaft and pulley, a rear bearing installed on the opposite side of a pulley, a steel cooling fan installed on both ends of a rotor, a stator core that protects the exterior of the rotor, a pair of brackets that support the rotor and stator core, a rectifier installed in the electrical bracket, and a brush holder with a voltage regulator.
13. A vehicle alternator with an enhanced cooling mechanism as claimed in Claim 12, wherein leaf units for 10. maintaining the shape of the cooling fan are installed on the circumference of the cooling fan.
14. A vehicle alternator with an enhanced cooling mechanism as claimed in Claim 12 or 13, wherein each blade of the cooling fan is angled at 700 relative to the main part of the cooling fan and the number of total blades formed is seventeen.
15. A fan for a vehicle substantially as hereinbefore described with reference to the accompanying drawings.

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