Active cooling of a motor

A motor, comprising an electronics housing, a stator having a stator bushing, and a rotor. The motor can be fastened to a fastening wall by means of the stator bushing. The motor according to the invention has an air conducting element and an air conveying element. The air conveying element is connected to the rotor in a rotationally fixed manner. The air conducting element surrounds the stator bushing and forms a flow space between the air conducting element and an outer circumference of the stator bushing. The flow space is open on the side of the electronics housing in the direction of the fastening wall through at least one flow gap. The air conducting element opens with an intake opening via a sealing gap in a rotor-side throughflow opening of the air conducting element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of PCT/EP2013/065098 filed on Jul. 17, 2013, which claims priority under 35 U.S.C. §119 of German Application No. 10 2012 107 107.1 filed on Aug. 2, 2012, the disclosures of which are incorporated by reference. The international application under PCT article 21(2) was not published in English.

The invention relates to a motor comprising an electronics housing, a stator having a stator bushing, and a rotor, wherein the motor can be attached to an attachment wall with the stator bushing.

Such motors are particularly used for driving fans and have integrated electronics, particularly commutation electronics. The maximal power range of the motors is generally limited by the maximal component temperatures of the electronics, for example of the electrical power components, such as power amplifiers, or of the motor, for example of the motor winding or of the ball bearings. The lifetime of the motor is also dependent on the component temperatures reached during operation of the motor, whereby elevated temperatures shorten the lifetime of the motor.

The motors are particularly attached to a stable attachment wall, which is part of an installation housing, for example, into which the fan is installed. In this connection, the electronics housing is generally inserted into an installation opening of the attachment wall, and the motor is attached to the attachment wall by means of the stator bushing. Such attachment makes effective cooling of the motor and of the electronics more difficult, because flow around the motor and the electronics housing in the axial direction of the motor is hindered by the attachment wall. Furthermore, particularly in the case of radial fans, flow around the motor is poor or does not occur at all, due to the radial outflow of the air. In the case of axial fans, what is called a dead water area is formed in the region of the rotor bell, and this also has a negative influence on flow around the motor.

The invention is based on the task of creating a motor, the cooling of which is improved and the power and lifetime of which are increased, at the same ambient temperature.

In the case of a motor of the type described initially, this task is accomplished, according to the invention, in that the motor has an air guide element and an air-conveying element connected with the rotor in torque-proof manner, wherein the air guide element surrounds the stator bushing, and a flow space is formed between the air guide element and an outside circumference of the stator bushing, wherein the flow space is opened in the direction of the attachment wall, on the side of the electronics housing, by means of at least one flow gap, and the air-conveying element opens into a through-flow opening of the air guide element, with an intake opening through a sealing gap.

Such a motor allows active and targeted cooling of temperature-critical components of the motor, particularly of the motor electronics and of the ball bearing of the stator, by means of an air volume stream generated by the air-conveying element. The air volume stream is guided, in targeted manner, to the components of the motor that are particularly supposed to be cooled, particularly to the stator bushing and to the region of the electronics housing, using the air guide element and the flow gap of the flow space, and reinforces the cooling in comparison with passive cooling, by means of convection brought about by the conventional ambient air. In this way, increased power and a longer lifetime of the motor are made possible.

In a preferred embodiment of the motor, the air-conveying element is configured as a radial fan wheel. The radial fan wheel draws the air volume stream in axially and blows it out radially, so that the air volume stream can be generated in particularly effective manner and so as to flow parallel to the motor axis.

Depending on the embodiment of the motor, cooling of the electronics housing is more important than cooling of the stator bushing, or, in the case of a special application or installation situation, the ambient air has a lower temperature in the region of the electronics housing than in the region of the rotor.

In a first embodiment of the invention, the air guide element can be attached to the attachment wall and is disposed between the attachment wall and the air-conveying element, wherein the intake opening of the air-conveying element is oriented in the direction of the attachment wall. In this connection, the air-conveying element generates a partial vacuum in the region of its intake opening and of the opposite through-flow opening of the air guide element during motor operation. By means of the air guide element, an air volume stream is guided through a channel opening disposed in the attachment wall and through the flow gap, into the flow space and along the outside circumference surface of the stator bushing, all the way to the through-flow opening of the air guide element, and axially drawn in by the air-conveying element, from the direction of the attachment wall, at its intake opening, and radially blown out in the region of the rotor. In this embodiment of the invention, the air volume stream to be cooled is at first drawn in the region of the electronics housing, and thereby the electronics housing is cooled particularly strongly, and the cooling effect in general is improved.

Alternatively, cooling of the stator bushing is more important than cooling of the electronics housing, or, in a special application or installation situation, the ambient air in the region of the rotor has a lower ambient temperature than in the region of the electronics housing.

In a second embodiment of the motor, the air guide element can be attached to the attachment wall and the air-conveying element is disposed within the air guide element, wherein the intake opening of the air-conveying element is oriented to face away from the attachment wall. In this connection, the air-conveying element generates a partial vacuum in the region of its intake opening during motor operation, and axially draws in the air to be cooled, through the through-flow opening of the air guide element, from the direction that lies opposite to the attachment wall, in the region of the rotor, and blows it out radially into the flow space. An air volume stream is guided through the flow space and along the outside circumference surface of the stator bushing, through the flow gap and through the channel opening of the attachment wall, all the way to an outside circumference of the electronics housing, by means of the air guide element. In the alternative embodiment of the invention, the air volume stream to be cooled is drawn in on the rotor side and thereby the stator bushing is at first cooled particularly strongly, and the cooling effect is improved, in general.

In a further embodiment of the invention, the motor comprises an air guide channel disposed on the outside circumference of the electronics housing, which channel can be attached to the attachment wall, wherein the air guide channel runs from a channel opening in the attachment wall, disposed in the region of the flow space, to a region on the outside circumference of the electronics housing, which region is to be cooled.

Such a configuration of the motor allows active cooling of the electronics housing even in the case of installation on an attachment wall having an installation opening, without requiring significant modifications of existing motor types, because no modifications of the electronics housing or of the stator bushing are required. Depending on the installation situation, only an additional connection opening in the attachment wall, for connecting air guide channel and air guide element, needs to be provided, or an existing opening needs to be enlarged or adapted, so that the air guide channel and the air guide element can be sufficiently connected with one another.

In a further embodiment of the invention, the air guide channel has a ring-shaped circumferential projection on its end that lies against the outside circumference of the electronics housing, which projection is particularly adapted to the outside circumference progression of the electronics housing or of the housing cooling ribs, respectively.

The projection increases the size of the surface area of the electronics housing that is covered by the air guide channel and is thereby cooled by the air volume stream.

In a further embodiment of the invention, the air-conveying element has a funnel-shaped ring collar on the side of the air guide element, at the edge of the intake opening, and the air guide element has a circumferential ring groove on the side of the air-conveying element, at the edge of the through-flow opening, wherein the ring collar projects into the ring groove, and ring collar and ring groove form the sealing gap. This allows improved sealing, in terms of flow technology, between the intake opening of the air-conveying element and the through-flow opening of the air guide element.

The same components are provided with the same reference symbols in all the figures.

FIG. 1,FIG. 2, andFIG. 3each show a motor according to the invention, particularly an external rotor motor. The motor comprises an electronics housing1, a stator comprising a stator bushing3and a laminated stator core4having motor windings, and a rotor5, particularly an external rotor. The stator bushing3and the electronics housing1are particularly made of metal. In the electronics housing1, there are motor electronics for drive and control of the motor, among other things, particularly commutation electronics having electrical power components such as power amplifiers. The electronics housing1has housing cooling ribs7on its outside wall, for cooling electronic components, not shown, within the electronics housing1. The stator bushing3has stator cooling ribs8on its outside wall, which ribs run radially and conduct away the heat that is generated by the stator, particularly by ball bearings and motor windings, not shown, which are installed in the stator.

For attachment, the motor is particularly mounted on a supporting construction10or on an attachment wall11having an installation opening30, by means of the stator bushing3. In an embodiment of the invention, the attachment wall11can be part of a supporting construction10configured as a component of the motor, so that the supporting construction10forms the attachment wall11. Alternatively, the attachment wall11can result from the installation situation, for example as a wall of an installation housing in which the motor is mounted. The motor is mounted in the installation opening30in such a manner that the electronics housing1is situated on the one side of the attachment wall11, and the stator as well as the rotor5of the motor is situated on the other side of the attachment wall11.

According to the invention, the motor has an air guide element22a,22band an air-conveying element14, both of which are configured in ring shape and surround the stator. In this connection, the air guide element22a,22bhas a through-flow opening26on the side of the rotor5. In the embodiment inFIG. 1andFIG. 2, the diameter of the through-flow opening26is particularly configured in such a manner that both the electronics housing1and the stator bushing3can be inserted through the through-flow opening26. This allows installation of the air guide element22aon the attachment wall11, independent of the motor. The air guide element22a,22bsurrounds the stator in the region of the stator bushing3, particularly in shell-like manner, and thereby a circumferential flow space35is formed between the air guide element22a,22band an outside circumference of the stator bushing3. The air guide element22a,22band the air-conveying element14particularly consist of plastic. During operation of the motor, the air-conveying element14is driven by way of the motor. The air-conveying element14is particularly configured as a radial fan wheel and mounted on the stator so as to rotate, and connected with the rotor5in torque-proof manner. In this connection, a ring opening17of the air-conveying element14is covered by the rotor5, on the rotor side. The air-conveying element14has a circumferential intake opening16that is open in the axial direction, which opening is connected, in terms of flow technology, in the interior of the air-conveying element14, with a circumferential blow-out opening18that is open in the radial direction. The intake opening16of the air-conveying element14lies opposite to the through-flow opening26of the air guide element22a,22b, wherein the air-conveying element14opens into the axial through-flow opening26of the air guide element22a,22bwith the axial intake opening16, by way of a sealing gap. In this connection, it is particularly advantageous if the air-conveying element14has a funnel-shaped ring collar29on the side of the air guide element22a,22b, at the edge of a circumferential wall of the intake opening16, and the air guide element22ahas a circumferential ring groove33on the side of the air-conveying element14, at the edge of the through-flow opening26, wherein the ring collar29projects into the ring groove33, and ring collar29and ring groove33form the sealing gap. This allows optimization, in terms of flow technology, of the transition from the air guide element to the air-conveying element. The air-conveying element14is configured in such a manner that it generates a partial vacuum at its intake opening16during motor operation, and radially blows out an air volume stream at its blow-out opening18.

On the side of the electronics housing1, a circumferential flow gap27is formed between the air guide element22a,22band the outside circumference edge of the stator bushing3, so that the flow space35is open in the direction of the attachment wall11on the side of the electronics housing1, wherein the flow gap27is axially covered, at least in part, in the installed state, by the attachment wall11. In the region of the flow gap27, the attachment wall11has at least one channel opening28, which runs axially. At least one air guide channel20is disposed on the outside circumference of the electronics housing1on the side of the attachment wall11that lies opposite to the air guide element22a,22b, and runs from the channel opening28of the attachment wall11, in the direction of at least one region of the electronics housing1that is to be cooled, on the outside circumference of the electronics housing1. The air guide channel20can particularly be attached to the attachment wall11and is particularly made of plastic. The air guide channel20has a ring-shaped circumferential projection21on its end that lies against the outside circumference of the electronics housing1, which projection is particularly adapted, in terms of shape, to the outside circumference progression of the electronics housing1, particularly of the housing cooling ribs7. As a result, the projection21, together with the end of the air guide channel20, covers a region of the housing cooling ribs7, in terms of circumference, and forms multiple cooling channels that run between the housing cooling ribs7.

In this embodiment of the motor, a selected region of the electronics housing1, covered by the end of the air guide channel20, is cooled in targeted manner. This is particularly the region in which the electronic components that must particularly be cooled are disposed in the interior of the electronics housing1. It is also conceivable, however, to dispose multiple channel openings28in the attachment wall11, in the region of the flow gap27, distributed over the circumference of the motor, so that multiple air guide channels20cool multiple regions of the electronics housing1.

In the first embodiment shown inFIG. 1andFIG. 2, the air guide element22acan be attached to the attachment wall11and is disposed between the attachment wall11and the air-conveying element14, wherein the intake opening16of the air-conveying element14is oriented in the direction of the attachment wall11. During motor operation, the air-conveying element14generates a partial vacuum in the region of its intake opening16and of the opposite through-flow opening26of the air guide element22a. An air volume stream is drawn in by way of the flow space35and the air guide channel20. In this connection, the air volume stream at first flows along the housing cooling ribs7of the electronics housing1, wherein it absorbs heat from the electronics housing1or from the surface of the housing cooling ribs7. As a result, the electronics housing1is cooled, thereby cooling specific electronic components to be cooled, which are disposed in the electronics housing1. The projection21of the air guide channel20additionally increases the size of the intake path through the housing cooling ribs7, and thereby reinforces the cooling effect. Afterward, the air volume stream flows through the air guide channel20and through the channel opening28of the attachment wall11, and through the flow gap27, into the flow space35and along the outside circumference surface of the stator bushing3, all the way to the through-flow opening26of the air guide element22a, and there is axially drawn in by the air-conveying element14, at its intake opening16, and radially blown out from the blow-out opening18, in the region of the rotor5. The air volume stream is distributed at the circumference of the stator bushing3, by means of the circumferential flow space35and the circumferential intake opening16of the air-conveying element14, and is particularly passed along the stator cooling ribs8of the stator bushing3, where it absorbs heat from the stator and from the surface of the stator cooling ribs8, respectively.

In the first embodiment of the invention, the air volume stream to be cooled is at first drawn in the region of the electronics housing1or through the air guide channel20on the outside circumference of the electronics housing1. As a result, the air volume stream comes into contact with the electronics housing1, at first, so that the electronics housing1is particularly strongly cooled. This is particularly advantageous if the ambient air has a lower temperature on the side of the electronics housing1than in the region of the rotor5.

In the second embodiment shown inFIG. 3, the air guide element22bcan be attached to the attachment wall11, and the air-conveying element14is disposed within the air guide element22b, wherein the intake opening16of the air-conveying element14is oriented to face away from the attachment wall11. The air guide element22balso surrounds the air-conveying element14. In comparison with the first embodiment, the air-conveying element14is rotated by 180°. As a result, the flow direction of the air volume stream changes. During motor operation, the air-conveying element14generates a partial vacuum in the region of its intake opening16and of the adjacent through-flow opening26of the air guide element22b, and axially draws in the air in the region of the rotor5, and radially blows out the air through the blow-out opening18, into the flow space35. As a result, an excess pressure is formed in the flow space35, thereby causing the air volume stream to flow along the outside circumference surface of the stator bushing3and, in particular, along the stator cooling ribs8, through the flow gap27and the channel opening28and the air guide channel20, wherein it absorbs heat from the stator or from the surface of the stator cooling ribs8, respectively, and cools the components of the stator. The air volume stream exits at the outside circumference of the electronics housing1, at the end of the air guide channel20, and is blown between the housing cooling ribs7, thereby additionally cooling the electronics housing1.

In the second embodiment of the invention, the cooling air volume stream is at first drawn in the region of the rotor5. As a result, the air volume stream at first comes into contact with the stator, so that the stator is cooled particularly strongly. This is particularly advantageous if the ambient air has a lower temperature on the side of the rotor5than in the region of the electronics housing1.

The invention is not restricted to the exemplary embodiments that are shown and described, but rather comprises all embodiments that have the same effect, in the sense of the invention. Furthermore, the invention is also not restricted to the combination of characteristics defined in each independent claim, until now, but rather can also be defined by any other desired combination of specific characteristics of all the individual characteristics disclosed in total. This means that fundamentally, practically any individual characteristic of the independent claim, in each instance, can be left out or replaced by at least one other individual characteristic disclosed at another point of the application. In this regard, the claims should be understood to be merely a first formulation attempt for the invention, in each instance.