Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-08-09
2001-09-04
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S064000
Reexamination Certificate
active
06285100
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is based on an electrical machine, preferably a rotary current generator or three-phase generator with a rectifier component.
In a known solution of the type mentioned above (U.S. Pat. No. 5,451,823), the positive and negative diodes of a rectifier component are each fastened to a cooling member or heat sink and electrically connected therewith by a connection. The heat sinks are fastened to the end face of an end shield for a rotary current generator so as to be sandwiched with an insulating plate added therebetween. The lower heat sink is attached to the end face of the end shield so as to be electrically and thermally conducting. A printed circuit board having a quantity of conductors embedded in the plastic of the printed circuit board for the connection of a positive diode and a negative diode on one side and having the winding ends of the rotary current winding in the stator of the rotary current generator on the other side is located on the upper heat sink. This rectifier component is held together by rivets and is fastened to the rotary current generator by screws. For purposes of cooling the upper curved heat sink, this heat sink is provided in the area of its inner circumference with a plurality of cooling slits which are arranged next to one another and oriented axially relative to the axis of the electrical machine; an axial cooling air flow is sucked in at the front side through the cooling slits from the outside toward a fan which is fastened to the rotor of the generator. The cooling air is blown radially outward through slits at the outer circumference of the end shield by fans in a known manner.
A disadvantage in this known solution is that the openings provided in the upper heat sink of the rectifier component for the flow of cooling air have relatively small cooling surfaces for dissipation of heat, so that a relatively thick upper heat sink is needed in order to achieve an adequate cooling surface at the cooling air openings. As a result of the accumulation of material required in this case, the upper heat sink used in this case is correspondingly expensive and heavy. Further, in order to achieve a large cooling surface for the cooling air flow, the openings in the heat sink are constructed as narrow, radially extending slits which again present a relatively high air resistance for the cooling air flow. The air volume sucked in through these slits and therefore also the cooling effect are accordingly small. The use of more powerful fans leads to higher costs and increased flow noise.
It is the aim of the present solution to improve the cooling performance by rearranging the rectifier component.
SUMMARY OF THE INVENTION
The electrical machine according to the invention has the advantage that the cooling air flow covers a considerably larger cooling surface of the heat sink without increasing flow resistance in that axially extending cooling fins are formed on at the openings of the upper heat sink. This results in the additional advantage that the cooling air openings are no longer constructed as slits, but rather can be substantially larger so that the air throughput is increased independent from the fan and the dissipation of heat from the rectifier component is accordingly improved and flow noise is reduced. Moreover, the upper heat sink can be constructed so as to be thinner, which leads to considerable savings in material.
It is particularly advantageous when there is a distance between the upper heat sink and the printed circuit board, which distance forms an air gap at the front side of the heat sink for a radial flow of cooling air from the outer circumference of the upper heat sink to some of its cooling air openings at the inner circumferential area. It is also advantageous when, instead of this, there is a space between the upper heat sink and the insulating plate arranged on the lower heat sink, which space forms an air gap at the rear of the upper heat sink for another radial flow of cooling air from the outer circumference of the upper heat sink to at least the inner circumferential area of the lower heat sink. Finally, an optimum cooling action at the upper heat sink is achieved in that the upper heat sink is exposed on both sides to a cooling air flow in that a first radial cooling air flow is conducted between the upper heat sink and the printed circuit board situated in front of the latter and another radial cooling air flow is conducted between the upper heat sink and the insulating plate located behind the latter from the outside radially inward to the fan.
REFERENCES:
patent: 4606000 (1986-08-01), Steele et al.
patent: 4952829 (1990-08-01), Armbruster et al.
patent: 5331231 (1994-07-01), Koplin et al.
patent: 5473208 (1995-12-01), Stihi
patent: 5646838 (1997-07-01), Keidar et al.
patent: 5659212 (1997-08-01), DePetris
patent: 1151857 (1969-05-01), None
patent: 58-172961 (1969-05-01), None
Bilsing Thomas
Bolz Ludwig
Knappenberger Uwe
Pflueger Gerhard
Robert & Bosch GmbH
Striker Michael J.
Tamai Karl
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