Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1996-05-30
1999-01-19
Dougherty, Thomas M.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 58, 310 60R, 310 60A, H02K 900, H02K 914, H02K 510
Patent
active
058616888
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a drive unit including an electric motor and a pot-shaped drum that accommodates and is driven by the electric motor. The pot base of the drum is connected to the drive-side shaft of the electric motor. The pot base includes at least one through-hole.
BACKGROUND OF THE INVENTION
Such a drive unit is disclosed in EP-A-0 423 616. In order to enable flow of a sufficient quantity of cooling air through holes in the pot base, axially projecting vanes are assigned to the holes on the outside of the pot base. If such a drive unit is not equipped with a separate protective grating, then there is an increased risk of injury from the projecting vanes.
When such a drive unit is used in textile operations, there is also a risk of fluff becoming trapped on the vanes and, consequently, of the holes provided in the pot base becoming blocked as a result of the normally high incidence of fluff. As a result, sufficient cooling of the motor inside the drum is no longer ensured.
Also, GB-A-2 160 924 discloses an axial fan in which the drive motor is seated in the hub, which is designed in the form of a bell, of the axial impeller wheel. Openings are provided in the transition region of the bell base, which is connected to the motor shaft, leading to the bell wall for passage of cooling air flow therethrough. This air flow passes between the surface of the drive motor and the inside of the bell wall. The cooling air flow receives its drive energy from the pressure difference produced between the two vane sides of the axial impeller wheel.
OBJECTS AND SUMMARY OF THE INVENTION
One object of the present invention is to provide a drive unit providing sufficient cooling air flow without any conveying means on the outer surface of the drive unit.
This object is achieved according to the invention by providing at least one web extending in the axial direction of the drive unit and projecting radially into the gap between the housing of the electric motor and the inner wall of the drum. The at least one web is arranged on the housing of the electric motor and/or on the drum inner wall, and the radial length of the web is less than the radial width of the gap. Ram-air pressure is produced on the web or webs projecting into the gap as a result of the rotation of the drum. This ram-air pressure leads to air movement in the gap. A flow movement of this sort in the gap is also achieved by a drive unit, in which the drum inner wall extends obliquely towards the pot base, which is provided with through-holes, or towards the open side of the drum. The heat dissipation from the electric motor is improved by the air movement produced in the gap in this manner without any external conveying means.
The conveying effect of both the webs and the through-holes can be enhanced by arranging or designing them such that they in each case extend obliquely with respect to the axial direction of the drive unit.
Favorable flow conditions are achieved if the drum inner wall extends obliquely outward towards the pot base, and the through-hole is provided in the pot base such that it is aligned with respect to the drum inner wall. In this case, it is again advantageous that the through-hole is constructed such that it extends obliquely at the same gradient as the gradient of the drum inner wall. This results in the flow moving smoothly without any direction changes.
An increase in the quantity of cooling air conveyed can be achieved by a drive unit, in which the at least one web, which extends in the axial direction of the drive unit and projects radially into the gap between the housing and the drum inner wall, is arranged on the housing of the electric motor and/or on the drum inner wall.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in greater detail in the following detailed description, with reference to exemplary embodiments illustrated in the drawings, in which:
FIG. 1 is a longitudinal section view taken through a drive unit in accordance with one embodiment of the inventi
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Adelski Hans-Joachim
Gempel Hans
Wagner Herbert
Dougherty Thomas M.
Nguyen Tran N
Siemens Aktiengesellschaft
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