Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-03-06
2001-01-30
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S179000, C310S180000, C310S263000, C310S06000A
Reexamination Certificate
active
06181045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an alternator for a vehicle such as a passenger automotive vehicle or a truck.
2. Description of the Related Art
There have been various proposals to provide small-size high-power alternators for vehicles.
Japanese published unexamined patent application 6-46550 discloses a way of improving the power generation performance which uses a permanent magnet.
To meet demands for downsizing, it is necessary to use a small-size cooling fan in an alternator. The rate of air flow generated by the small-size cooling fan is relatively low. On the other hand, a high-power alternator generates an increased rate of heat. Thus, a high-power alternator with a small-size cooling fan tends to have the problem of a temperature rise.
Accordingly, to provide a small-size high-power alternator, it is necessary to remove the problem of a temperature rise. Especially, it is necessary to implement effective heat radiation from electric conductors in a power generating stator under the size restrictions.
Japanese published unexamined patent application 7-194060 discloses that water having a high heat radiation efficiency is used as coolant for an alternator. The alternator in Japanese application 7-194060 needs pipings for the cooling water, and a water jacket in the alternator body. Accordingly, the alternator in Japanese application 7-194060 tends to be heavy and large in size. Thus, the alternator in Japanese application 7-194060 does not meet demands for downsizing.
General prior-art air-cooling techniques have a step of decreasing the temperature of coil end portions of electric conductors in a stator. The coil end portions are also referred to as the bridge portions.
Japanese published examined patent application 4-24939, Japanese published unexamined patent application 63-59744, Japanese published examined utility model application 1-27406, and Japanese published unexamined patent application 57-132743 disclose improvements on bridge portions.
According to these prior-art air-cooling techniques, pieces of an electric conductor which form bridge portions are arranged so that winds can efficiently flow therebetween and improved heat radiation can be attained. In the prior-art air-cooling techniques, bridge portions of electrical conductive wires are partially spaced from each other, and are in a flat and regular arrangement as a whole. In the prior-art air-cooling techniques, the bridge portions interfere with paths for cooling winds, and hence offer great resistances to the cooling winds. An impregnation agent for fixing the bridge portions covers the surfaces thereof, and provides an increased resistance to the cooling winds. Accordingly, the prior-art air-cooling techniques are poor in cooling performance.
In a general prior-art structure, an electric conductor in a stator is coated with an insulating film, and an impregnation agent for fixing the electric conductor is applied onto the insulating film. It is well-known that the insulating film considerably deteriorates the heat radiation from the electric conductor. Since sufficient insulation is necessary, it is impractical to remove or thin the insulating film.
In a prior-art structure, the heat resisting property (the allowable temperature) of electric conductors coated with insulating layers is decided by the heat-deterioration temperature of the insulating layers in a region where the electric conductors overlap each other. Thus, it is difficult to improve the heat resisting property (the allowable temperature).
SUMMARY OF THE INVENTION
This invention has been carried out in view of the above-mentioned problems.
It is an object of this invention to provide an alternator for a vehicle in which all electric conductors forming bridge portions are sufficiently exposed to cooling winds so that the cooling performance is remarkably improved.
It is another object of this invention to provide an alternator for a vehicle which is excellent in cooling performance, insulating performance, and heat resisting property.
In order to attain the above-mentioned objects, this invention is designed as follows.
According to this invention, pieces of an electric conductor in bridge portions are spaced from each other, and insulating layers in the bridge portions are thinner than insulating layers in accommodated portions placed in slots.
According to this invention, electric insulating members are provided between the accommodated portions of the electric conductor and a core, and provide electric insulation between the accommodated portions of the electric conductor and the core. On the other hand, pieces of the electric conductor in the bridge portions are spaced from each other to provide electric insulation between the pieces of the electric conductor in the bridge portions.
According to this invention, the bridge portions of the electric conductor are smaller in cross-sectional area than the accommodated portions of the electric conductor.
According to this invention, the bridge portions of the electric conductor are spaced from each other by a distance of 0.5 mm or more, and are electrically insulated from each other.
According to this invention, a cooling fan is disposed at least at one axial end of the rotor opposing the stator.
According to this invention, the bridge portions of the electric conductor have first portions and second portions, the first portions extending and inclining in circumferential directions, the second portions extending in radial directions. In addition, axial-direction positions of the second portions are in an axial-direction range where the cooling fan is present.
In this invention, R′>r≧R>r′ for at least one side of the stator and the rotor, where R denotes a radial-direction inside diameter of the bridge portions of the electric conductor, and R′ denotes an inside diameter of the iron core, and r denotes a pole core outside diameter of the rotor, and r′ denotes an outside diameter of the cooling fan.
According to this invention, the electric conductor comprises a plurality of approximately U-shaped segments having straight portions inserted into the slots, and one side surface of the iron core is formed by turn portions of the U-shaped segments. In addition, the straight portions are uniformly arrayed and accommodated in said slots.
According to this invention, the insulating layers comprise insulating cover films on the electric conductor, and fixed insulating films formed by an impregnation process, and the bridge portions have only the insulating cover films or the fixed insulating films.
According to this invention, the insulating layers are absent from the electric conductor in the bridge portions. Thus, the electric conductor is naked metallic members at the bridge portions.
In this invention, pieces of the electric conductor in the bridge portions are spaced from each other, and the insulating layers in the bridge portions are thin. Therefore, the heat radiation from the surfaces of the electric conductor is remarkably improved, and a rise in the temperature of the electric conductor can be effectively suppressed. Thus, the heat deterioration of the insulating layer is suppressed. Since the pieces of the electric conductor in the bridge portions are spaced from each other, it is possible to improve both the heat resisting property (the allowable temperature) and the insulating performance related to the electric conductor.
In this invention, electric insulating members are provided between the accommodated portions of the electric conductor and the core of said stator, and provide electric insulation between the accommodated portions of the electric conductor and the core. On the other hand, pieces of the electric conductor in the bridge portions are spaced from each other to prevent the pieces of the electric conductor in the bridge portions from interfering with each other and also to provide electric insulation between the pieces of the electric conductor in the bridge portions.
In this invention, the
Kusase Shin
Shiga Tsutomu
Umeda Atsushi
Denso Corporation
Mullins Burton
Pillsbury Madison & Sutro LLP
LandOfFree
Alternator for vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Alternator for vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alternator for vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2549548