DE102009022722B4 - Electric motor with fan - Google Patents

Abstract

Electric motor with fan, comprising rotor blades (1), the fan being connected in a rotationally fixed manner to the rotor shaft (4), the fan being designed as an axial fan and being constructed symmetrically, and each rotor blade of the fan being constructed symmetrically in such a way that the sectional structure of the rotor blade is also different Radial distances to the rotor axis tangential planes is always an ellipse, which means that regardless of the direction of rotation of the rotor shaft (4), the fan has the same air delivery rate, the area surrounded by the ellipse in the plane decreasing with the radial distance to the rotor axis, the fan forming a fan ring (2), with which the radially outer ends of the rotor blades (1) are connected, the conveyed cooling air flow being guided along the outside of the stator with the suction or blowing action of the fan depending on the direction of rotation of the fan, the motor housing being tubular Sheath housing part (6), welc hes together with the stator of the electric motor forms a flow channel (7), the casing housing part (6) delimiting the flow channel (7) radially outwards and radially inward the flow channel (7) being delimited by the stator of the electric motor, on the outside of the stator cooling fins are arranged for improved steering of the cooling air flow and for improved heat transfer, the cooling fins running in the axial direction.

Description

The invention relates to an electric motor with a fan.

It is known to equip electric motors with fans in order to improve the heat dissipation of the electric motor and thus to achieve high performance with a small construction volume.

From the DE 102 46 311 A is known as the closest prior art, a fan with blades, the line-shaped cross section increases with increasing radial distance.

From the EP 1 936 206 A1 a fan is known, the blades of which have a variable angle of attack.

From the DE 1864059 U a grill fan with blades is known, the line-shaped cross section increases with increasing radial distance.

From the DE 100 44 066 A1 an electric fan with blades is known, the line-shaped cross-section does not depend on the radial distance.

From the US 2 912 159 A a fan with blades is known, the cross section of which is point-symmetrical but has no mirror symmetry.

From the US 2 609 055 A a reversible fan is known.

The invention is therefore based on the object of developing an electric motor, the electric motor being intended to be versatile.

According to the invention the object is achieved in the electric motor according to the features specified in claim 1.

The advantage here is that the motor can be used in a variety of ways, since a cooling air flow sweeps past the motor in every direction of rotation, thus ensuring efficient cooling. The fan is sucking in one of the directions of rotation and blowing in the other direction of rotation. In the suction mode, a small negative pressure is created in the area of the motor and in the blowing mode, a small excess pressure is created in the area of the motor. The cooling air flow preferably sweeps past the outside of the stator, in particular thus the motor housing. Cooling fins can be provided on the outside for improved guidance and to reduce the swirling of the cooling air flow.

According to the invention, the fan, in particular the rotor blades of the fan, is designed in such a way that the fan has essentially the same delivery rate regardless of the direction of rotation of the fan wheel. The advantage here is that both operating modes of the electric motor allow the full drive power of the motor, so that the maximum permitted speed and the maximum permitted torque can be generated in both directions of rotation without a critical overtemperature.

According to the invention, the sectional structure of the rotor blade with a tangential plane lying at different radial distances from the rotor axis is an ellipse. The advantage here is that depending on the desired performance and commercially acceptable manufacturing costs, corresponding rotor blades can be used.

In an advantageous embodiment not according to the invention, the sectional structure is independent of the radial distance from the rotor axis, that is to say it is unchangeable at different radial distances. The advantage here is that a simple construction and simple manufacture can be carried out, in particular also the manufacture of an injection molding tool when manufactured from plastic.

According to the invention, the area surrounded by the ellipse in the plane decreases with the radial distance from the rotor axis. The advantage here is that an embodiment that is optimized in terms of efficiency can be implemented.

According to the invention, the fan has a fan ring to which the radially outer ends of the rotor blades are connected. The advantage here is that the stability can be increased and the axial air flow can be conducted better by means of the fan ring, that is to say with lower eddy losses.

In an advantageous embodiment, the housing of the motor or the outer surface of the stator is designed such that it is rounded, in particular curved, in such a way that the air flow conveyed by the fan passes between the housing of the motor or the outer surface of the stator and a jacket housing surrounding the housing and the stator becomes. The advantage here is that flow losses are minimized and the resulting flow can be influenced in such a way that optimal cooling performance is achieved.

Further advantages result from the subclaims.

• In der 1 Draufsicht auf einen erfindungsgemäßen Elektromotor schematisch dargestellt.
• In der 2 ist ein zugehöriger Querschnitt schematisch skizziert.
• In der 3 ist ein erfindungsgemäßer Lüfter in Schrägansicht gezeigt.

The invention will now be explained in more detail with reference to figures:

• In the 1 Top view of an electric motor according to the invention is shown schematically.
• In the 2 an associated cross section is schematically outlined.
• In the 3 an inventive fan is shown in an oblique view.

The fan has a fan hub 3 on that can be connected in a rotationally fixed manner to the rotor shaft 4 which is the rotor 5 carries and is mounted in the motor housing, in particular in an A-side and a B-side flange part which are screwed to the motor housing.

There are radially extending rotor blades on the fan hub 1 attached, the respective radial end portion with an air guide ring 2 are connected.

The motor housing has a casing part 6 on which of the flow channel 7 limited radially outwards. The flow channel is radially inward 7 limited by the stator of the electric motor.

At its axial end areas this is from the casing housing part 6 The housing formed is designed to be open in the axial direction, with radial motor supports 8th extend radially. The air flows on these engine mounts 8th over, so that they also act as cooling fins.

The stator is formed by means of a laminated core and has a three-phase winding as a stator winding. The laminated core is rounded in each case at its axial end regions, so that the axially flowing air driven by the fan flows past the stator with only a slight swirl.

The fan is designed in such a way that, regardless of the direction of rotation of the fan, the air is always conveyed with the same flow rate, namely towards or away from the motor, in particular the stator. The air flow is essentially the same and thus the amount of air delivered per unit of time. The air flows along the outside of the stator, in particular thus on the motor housing. Since the maximum of the conveying effect is effected at a large radial distance, that is to say in the radially outer region of the fan blades, and these are located at approximately the same radial distance as the cooling fins, an only insignificant change in the conveying capacity is effected when the direction of rotation changes.

The conveyed air flow thus flows through the flow channel 7 and heats the stator of the motor.

To reduce flow losses and to influence the flow profile with regard to optimal heat dissipation, the stator is curved at its axial end region facing the fan. The curvature is designed such that with increasing axial distance from the fan, the curvature of the surface of the stator does not rise suddenly but slowly.

The fan, especially the rotor blades 1 , are arranged symmetrically in such a way that in both directions of rotation of the fan, ie the fan wheel, the air is conveyed in the axial direction essentially to the same extent.

The fan, especially the rotor blades 1 , are arranged in such a way that when the fan is mirrored at that center plane, the normal of which is oriented in the axial direction and which contains the center of the fan, and a subsequent axially reversed mounting of the fan, the fan arrangement is unchanged.

This means that after mirroring on the axial center plane and subsequent axially reversed assembly, i.e. rotation by 180 ° about an axis of rotation perpendicular to the rotor axis which is contained in the center plane, each rotor blade remains unchanged with the exception of the rotational position of the fan. More specifically, each rotor blade remains unchanged even if it is mirrored on the axial center plane and subsequently rotated about an axis of rotation perpendicular to the rotor axis which passes through the axial center or center of gravity.

The rotor blade is preferably constructed in such a way that the sectional structure of the rotor blade is always the same with tangential planes lying at different radial distances. The sectional structure preferably has two mirror symmetries, the mirror axes being perpendicular to one another. It is designed according to a narrow ellipse.

In the radial direction, the sectional structure is formed in an angular position that increases strictly monotonously with the radial distance, the angle to the rotor axis being measured.

Alternatively, the sectional structure is formed in an angular position that decreases monotonically with the radial distance.

In an exemplary embodiment not covered by the invention, the length of the sectional structure increases in the direction of the elongated shape of the sectional structure with increasing radial distance from the rotor axis. Likewise, the width of the sectional structure does not have to be constant with increasing radial distance from the rotor axis.

According to the jacket housing part 6 tubular, especially with a smooth outer surface.

There are also cooling fins for air cooling on the outer surface of the shell housing part 6 possible.

LIST OF REFERENCE NUMBERS

1

rotor blade

2

air guide

3

fan hub

4

rotor shaft

5

rotor

6

Mantle housing part

7

flow channel

8th

Motor mount as cooling fins

Claims (3)

Electric motor with fan, comprising rotor blades (1), the fan being rotatably connected to the rotor shaft (4), the fan being designed as an axial fan and being constructed symmetrically and each rotor blade of the fan is constructed symmetrically such that the sectional structure of the rotor blade with tangential planes lying at different radial distances from the rotor axis is always an ellipse, whereby the fan has the same air flow rate regardless of the direction of rotation of the rotor shaft (4), the area surrounded by the ellipse in the plane decreases with the radial distance from the rotor axis, the fan having a fan ring (2) to which the radially outer ends of the rotor blades (1) are connected, the conveyed cooling air flow is conducted along the outside of the stator with the suction or blowing mode of operation of the fan depending on the direction of rotation of the fan, the motor housing having a tubular casing part (6) which, together with the stator of the electric motor, forms a flow channel (7), the casing housing part (6) delimiting the flow channel (7) radially outwards and the flow channel (7) being delimited radially inwards by the stator of the electric motor, cooling fins are arranged on the outside of the stator for improved control of the cooling air flow and for improved heat transfer, the cooling fins running in the axial direction. Electric motor after Claim 1 , characterized in that at its axial end regions the housing formed by the casing housing part (6) is designed to be open in the axial direction, with radial motor supports (8) extending radially and the cooling air flow flowing past these motor supports (8) so that they also act as cooling fins , Electric motor according to one of the preceding claims, characterized in that the housing of the motor or the outer surface of the stator is curved and / or rounded such that the air flow conveyed by the fan between the housing of the motor or the outer surface of the stator and the one Flows through the housing and the casing surrounding the stator.

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