Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2003-01-16
2004-04-20
Le, Dang (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S064000, C310S089000
Reexamination Certificate
active
06724108
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to an AC (alternating current) generator, and in particular, to an automotive AC generator with a rectifier capable of rectifying generated AC power into DC (direct current) power.
2. Description of Related Art
In a recent automotive vehicle, an effective capacity inside the passenger compartment has been desired to be larger. In realizing such an object, one countermeasure is to reduce the space of the engine room. It is also required that an automotive AC generator be downsized.
Under such circumstances, a significant subject to be resolved is that the cooling performance of a rectifier mounted to the automotive AC generator is maintained or improved. This subject is not an easy matter, because saving the space in the engine room will lead to deteriorated temperature environment therein and downsizing the automotive AC generator itself will lead to deterioration in the cooling efficiency thereof.
FIG. 10
shows an automotive AC generator according to a first conventional example. This generator adopts a configuration for improving the cooling efficiency, in which both of positive and negative fins
101
and
102
on which rectifying elements
100
are mounted are arranged, in an overlaid fashion, in parallel to each other in an axial direction thereof. A protective cover
103
has two cooling air inlets
104
opened at predetermined portions near the rectifying elements
100
. Cooling air is thus directly introduced to the rectifying elements
100
(precisely, to the back surfaces of the fins
101
and
102
) are cooled down by the introduced cooling air.
However, the above first conventional example has an inconvenience, which is concerned with the circulation of the cooling air. To be specific, the cooling air that has been introduced is directly blown onto a predetermined region on each of the backs of the cooling fins
101
and
102
, such a region almost corresponding to each of the positions of the rectifying elements
100
or thereabout. But the cooling air is reluctant to circulating around each of the cooling fins
101
and
102
toward the surface on which element connection terminals are located thereon, respectively. In addition, one rectifying element located outward in the radial direction is placed in the downstream flow of the cooling air that passes by the other rectifying elements. Thus, it is obliged that the rectifying elements located radially outward are cooled down by the cooling air of which temperature has already been raised considerably. Therefore, the above cooling configuration has faced the problem that the cooling efficiency was not sufficient.
In consideration of the above inconvenience, the present applicant has already provided a second conventional example according to Japanese Patent Laid-open publication No. 11(1999)-164538, which is typically shown in
FIGS. 11 and 12
. This example concerns an automotive AC generator that has a larger-diameter fin
503
located near to a rear frame
3
b
and a smaller-diameter fin
501
located near to a protective cover
8
. Rectifying elements
502
and
504
are arranged on the fins
501
and
503
, respectively, in the axial direction of the generator. The rectifying elements
502
and
504
come face to face with each other with a predetermined gap left therebetween, but both the fins
501
and
503
are mutually shifted outward or inward in the radial direction. The protective cover
8
has axial openings
801
, each of which permits air to pass therethrough directly to each positive rectifying element
502
. Additionally, there is formed a radial air passage
801
between the larger-diameter fin
503
and the rear frame
3
b
in such a manner that the air passage
801
passes by the central position of each of the negative rectifying elements
504
. A radial opening
802
that allows air to be directly introduced to one end of the radial air passage
810
that is located outward in the radial direction. This cooling configuration causes the cooling air to circulate the gap between both the element-mounting surfaces of the fins
501
and
503
. Hence the cooling air that has been taken in passes along the surfaces of the cooling fins
501
and
503
on which the rectifying elements
502
and
504
are disposed, respectively.
In the above automotive AC generator according to the second conventional example, however, there is still a problem that the larger-diameter fin
503
may suffer from a shortage of the cooling capacity, although the radial air passage
810
allows the cooling air to pass along the frontal and rear surfaces of the larger-diameter fin
503
. Practically, if the amount of flow of air from a cooling fan
21
is reduced on account of, for example, making the entire size of the automotive AC generator compact, the amount of flow of cooling air that passes the radial air passage
810
formed between the rear frame
3
b
and the larger-diameter fin
503
is also reduced. In such an occasion, the cooling performance for the larger-diameter fin
503
will decrease, with the result that the rectifying elements
504
secured on the larger-diameter fin
503
are subjected to a rise in its temperature.
SUMMARY OF THE INVENTION
The present invention has been performed in consideration of the above-described drawback, and an object of the present invention is to provide an automotive AC generator with a rectifier including a larger-diameter fin, which is able to provide the larger-diameter fin with cooling air in a more effective way so that the cooling performance of the larger-diameter fin is increased dramatically.
In order to achieve the above object, the present invention provides a vehicle AC generator comprising: a frame, having a radial direction and an axial direction, formed to have an inner wall area, a radially inner end, and a radially outer end in the radial direction and an outer end portion in the axial direction; a stator secured on the inner wall area of the frame; a rotor rotatably supported at the frame; a rectifier including a plurality of rectifying elements and being secured on the outer end portion of the frame, said plurality of rectifying elements being classified into a first group of rectifying elements and a second group of rectifying elements; a protective cover having an inner end portion and being secured on the outer end portion of the frame to cover the rectifier; and a cooling fan secured at the rotator and configured to take in cooling air from one side on which the rectifier is located. The rectifier comprises a larger-diameter fin disposed to extend in the radial direction with facing the outer end portion of the frame, said larger-diameter fin serving as both of a cooling member for the first group of rectifying elements and a connecting conductive member of the first group of rectifying elements mounted on the larger-diameter fin; and a smaller-diameter fin disposed to face the inner end portion of the protective cover, said smaller-diameter fin serving as both of another cooling member for the second group of rectifying elements and another connecting conductive member of the second group of rectifying elements mounted on the larger-diameter fin. The protective cover comprises an axial opening facing the smaller-diameter fin and being formed through the frame to take cooling air in. The frame comprises a radial opening formed with the aid of the radially outer end of the frame to take cooling air in, a radial air passage formed with facing the larger-diameter fin and formed to circulate the cooling air taken in through the radial opening along the larger-diameter fin inwardly in the radial direction, and a plurality of grooves each positionally corresponding to a mounted position of each rectifying element on the larger-diameter fin and being formed on the radial air passage to connect the radially outer end and the radially inner end of the frame.
Accordingly, the cooling air taken in through the radial opening is able to cool down the larger-diameter fin.
Denso Corporation
Le Dang
Oliff & Berridg,e PLC
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