Patent Grant
7781926
The present invention relates to an electric motor and a series of electric motor(s).
German Published Patent Application No. 197 04 226 describes an electric motor, where an adapter and a cover are put onto the housing of the stator, an electronic circuit having the functionality of a converter being provided in the interior chamber. In this context, it is disadvantageous that the converter is thermally insulated in the direction of the motor. Consequently, a high-power cooling body must be connected to the converter. This cooling body is provided on the converter in the direction of the motor and disadvantageously requires a large unit volume. It is also difficult and expensive to manufacture. In particular, a design having cooling fingers is associated with high expenditure.
The terminal box, i.e., connection box, of the electric motor is not axially mounted, but laterally. However, in the case of some systems, there is little space available on the side of the motor.
Example embodiments of the present invention may provide an electric motor and a series of electric motors that includes different variants. In this context, however, the storage volumes and the costs may become reducible.
According to an example embodiment of the present invention, an electric motor includes at least a stator, a rotor, and a housing, the housing having at least one first mechanical interface that is provided for connection to a bearing support, the bearing support including at least a bearing seat for the B-side bearing of the rotor shaft, the bearing support including a further interface for connection to a bottom part, the bearing support forming a housing, e.g., for a brake and/or a fan, the bottom part having an interface for connection to a cover, the bottom part forming a housing for at least power electronics, whose heat may be discharged directly, or at least indirectly, to the bottom part, the bottom part being connected to the bearing support in a thermally conductive manner, so that the heat of the power electronics may be discharged by the bearing support to the surrounding air.
In this context, it may be provided that no special cooling body is necessary, but that the B-side bearing support of the electric motor may be used for dissipating heat. Consequently, the entire electric motor may be designed to be more compact, and, e.g., the lateral space is small.
In this context, power electronics should be understood to be at least the part of the electronic components that may control, e.g., switch, the motor currents. For a deliverable motor output of greater than 500 W, a power-electronics heat loss of greater than 20 W, e.g., up to 300 W, normally occurs, which is to be ultimately discharged to the environment. The heat loss to be dissipated increases by a value between 20 and 80 Watt per kW of motor output.
In a modular system, the electric motors include at least a stator, rotor, and a housing, the modular system including several variants of electric motors, e.g., within one size, the housing having a mechanical interface that is designed for connection to a bearing support, the bearing support including at least a bearing seat for the B-side bearing of the rotor shaft, at least two different bearing supports being alternatively connectible to the housing, a first bearing support including an additional interface for connection to a bottom part of a terminal box, or alternatively to a bottom part for power electronics, and the first bearing support forming a housing for a brake and/or a fan, a second bearing support being constructed in one piece with a bottom part of a terminal box.
It may be provided that many different variants may be produced using as few components as possible. A variant, which is as compact as possible, is obtainable for each functional requirement, using as few components as possible. The modular system, i.e., the series, may only provide bearing supports having different interfaces. The housing of the stator remains unchanged. Therefore, it is usable in all of the variants of the series. The interfaces of the bearing support to the housing of the stator allows different bearing supports to be attached. In the case of one of these bearing supports, a terminal box may be integrated. In the case of another, it is detachably connectible and may be alternatively replaced with a converter. The last-named interface to the terminal box may even be oriented to be offset 90° from the interface to the stator. Therefore, it does not have to be coaxially mounted.
The B-side bearing support, and not the housing of the stator, may be used for variation within the series. It not only allows the stator and rotor plates to be constructed in a substantially identical manner, but also allows, depending on the requirement, different unit volumes of the bearing support to be obtained, together with the terminal box or the converter housing, in the B-side region. However, in the majority of the machines and systems in which electric motors are installed, more volume is available in the B-side region than in the A-side region or in the region over the front axial, i.e., A-side, region of the stator housing. In addition, for maintenance work, easier access is possible in the B-side region than in the A-side region.
The connections may be constructed to be impervious and detachable, using seals. Therefore, a high degree of protection is achievable, e.g., at least IMP.
The interfaces of the bearing support are provided for mechanical connection to the above-mentioned parts. In addition, the bearing support also has other functions, e.g., the function of discharging heat of the power electronics from the interior chamber of the terminal box or converter. In each case, the bearing support may always carry out the function of forming a housing for a fan rotating with the rotor shaft. This supplies cool surrounding air and consequently increases the heat flowing from the bearing support to the environment.
A further integrated function of the bearing support is to act as the guide device for the armature disk and friction disk of the optionally present brake in the axial direction. Therefore, the bearing support unites the mechanical functions of the retention force for the B-side bearing and the mechanical guide forces for the components of the brake, such as the armature disk, etc.
A housing cover may be connected to the bottom part, and a bottom part of a terminal box or bearing support may be connected to a one-piece lower part of a terminal box. In this context, it may be provided that an interior region sealed off to have a high degree of protection may be provided for sensitive electronics.
The lower part or lower part of a terminal box may be connected to the bearing support in at least two different orientations, e.g., in orientation directions offset 90° from one another. It may be provided that the optimum orientation may be selected as a function of the requirement of the application, i.e., the type of construction of the machine or system.
Soft-start electronics may be provided instead of the converter electronics. It may be provided that costs are reducible, since the developmental expenditure of soft-start electronics is less, and they may also be manufactured using fewer components.
At least the first bearing support may have a precision-machined contact surface for connecting it to the power electronics in a thermally conductive manner. In this context, it may be provided that the bearing support may be used as a mechanical mount and heat-dissipating device.
The power electronics may be connected to the bearing support in a thermally conductive manner for discharging heat to the environment. It may be provided that the heat is discharged to a part that may be cooled by a stream of cooling air.
The second bearing support may be arranged to have a sensor, which detects, at the circumference of the fan, physical characteristics of the fan or of a component connected to it. It may be provided that the fan has a larger diameter than the rotor shaft, and that the angular resolution may be consequently improved. In addition, no expensive, complicated sensor system is necessary, but rather a magnetic ring or a magnetic foil is sufficient.
The first bearing support may form a housing for an electromagnetically operable brake and/or a fan. It may be provided that the bearing support is cooled. In addition, an additional housing for the brake is not necessary.
The first and second bearing supports may each be connectible to the same kind of fan-hood grating. An advantage of this is that the same fan-hood grating may be used repeatedly within the series.
The housing of the stator may be connectible to a bearing support on the A-side, the bearing support including a bearing seat for accommodating the A-side bearing of the rotor shaft. It may be provided that the entire electric motor has three main housing parts, namely the housing of the stator and the two bearing supports. If an electric motor having a larger torque is necessary, only the rotor shaft, together with the rotor, the stator, and the housing of the stator, is to be exchanged for, e.g., parts that are axially longer, the remaining parts being able to be retained.
The bearing support may have guide devices for axially guiding the armature disk of the brake. In particular, the guide devices are arranged as cut-outs. It may be provided that no special part is necessary for carrying out the guide function, but that this function may be integrated into the bearing support.
Further aspects and features of example embodiments of the present invention are described in more detail below with reference to the appended Figures.
a and 1b are a plan view and sectional view of an electric motor of an example embodiment of the present invention, having a brake and a fan.
a and 2b are a plan view and sectional view of an electric motor of an example embodiment of the present invention, having a brake and fan, where a bottom part replacing the terminal box is provided, the bottom part, together with the attachable cover, surrounding electronics that function as a converter.
a and 3b are a plan view and sectional view of an electric motor of an example embodiment of the present invention, having a brake and a fan, the terminal box being formed in one piece with the B-side bearing support.
a and 4b are a plan view and sectional view of an electric motor of an example embodiment of the present invention, having a brake and a fan, the terminal box being formed in one piece with the B-side bearing support, and the fan supporting a sensor ring that is detectable by a sensor.
a and 5b are a plan view and sectional view of a bearing support according to an example embodiment of the present invention.
The bearing support, along with a connected terminal box, is illustrated in
A corresponding electric motor is illustrated in
A sensor is additionally illustrated in
An electric motor having a fan, but not a brake, is illustrated in
a and 10b are spatial, oblique front and back views of the bearing support and connected terminal box illustrated in
a and 11b are spatial, oblique front and back views of the bearing support illustrated in
Illustrated in
On its B-side end, the rotor shaft supports a fan 13 having fan blades 12. Provided axially in front of this is a brake, which includes a brake coil located in magnet body 3 and an axially movable armature disk 2. When current flows through the brake coil, armature disk 2 is pulled towards it, counteracting spring force being overcome by spring elements supported in the magnet body. When no current flows, the spring elements therefore press against the armature disk such that it is pressed onto the coating support, which supports brake coatings on the two axially oriented surfaces. The coating support is also connected to rotor shaft 7 in a form-locked manner in the radial and circumferential directions. Therefore, when no current flows through the brake coil, armature disk 2 presses coating support 5 onto the friction disk 11 positioned axially behind the coating support.
Housing 15 of the electric motor has a mechanical interface to bearing support 1, which means that bearing support 1 is connectible to housing 15 in a sealed, rigid, and exact manner. Bearing support 1 has a correspondingly matching interface.
Bearing support 1 has an additional, electric interface to the terminal box constructed as a connection box. This includes a housing cover 14 and a bottom part 4 of the terminal box, the bottom part being connectible to bearing support 1 in a sealed and rigid manner. A seal 16 is provided in the connection region for this purpose.
The interface between housing 15 and bearing support 1 may also be constructed to provide a sealed connection. Seal 17 is provided for this.
Bottom part 4 of the terminal box has screw-type conduit fittings 18 arranged as cable outlets. As an alternative, screw-type conduit fittings may be provided in the corresponding cover.
Seals 17, 16 may be arranged to function as a heat barrier. Consequently, the exchange of heat between the metallic parts, e.g., housing 15 and bearing support 1, may be sharply reduced. The exchange of heat between the bearing support and the bottom part of the terminal box may be sharply reduced.
An additional measure for reducing this heat exchange is to not make bottom part 4 of the terminal box out of metal, but out of plastic or another thermal insulator. Seal 16 may not only be arrangeable as a flat seal or O-ring, but also as a thermally insulating, injection-molded part, which separates the spatial region of bearing support 1, together with the brake and the fan, from the interior of the bottom part of the terminal box, or also from cover 14.
On the B side, bearing support 1 has an opening for air to pass through. For reasons of safety, it is terminated by a fan-hood grating 19.
As illustrated in
However, seal 16 may also be arranged to be thermally conductive, e.g., metallic contact surfaces provided around the spatial region of the seal may be increased in size, and therefore, a sufficiently large contact surface may be provided which causes a reduction in the heat-transfer resistance. This provides that bearing support 1 and the bottom part of the terminal box are effectively thermally coupled, i.e., they have a low heat-transfer resistance. Therefore, the heat may be discharged by the electronic circuit, through the bottom part of the terminal box, to not only the environment, but also the bearing support. Thus, a specially formed cooling body is not necessary, and on the whole, a smaller volume is necessary, e.g., laterally.
Seal 17 may also be designed to conduct heat. This is advantageous, when the temperature in the stator and the corresponding housing is constantly less than in the region of the bearing support and heat may therefore be conveyed to the stator and its housing. Consequently, the entire electric motor may be designed to be even smaller.
Bearing support 1 may be provided with the two, above-mentioned, specific interfaces. Consequently, components other than those illustrated in
It may also be provided that the electronics are arranged not in the axial direction, but rather radially, i.e., laterally. In this context, it may be provided that the overall length may be kept small. In the case of most machines and systems, a certain volume is available on the side and accessible to the operator, since the connection box of the motor lies mostly on the side and the overall length is more expensive with regard to the total cost. The laterally available volume is utilized, and the increase in volume needed in the lateral direction is insignificant. In particular, cooling with the aid of a fan allows the electronics to be manufactured to be small and therefore produces a small lateral volume. In addition, the cooling body may be arranged to be small, or may be neglected, since heat is discharged through the bearing support of the motor and discharged from it to the environment, via the stream of cooling air driven by the fan.
As illustrated in
Connection terminals 22 are provided on a printed circuit board 23, which is provided in the interior of lower part 26.
A further feature is that the axial end of the cover and of bottom part 26 is terminated in substantially the same axial position as the fan hood.
Provided in the interior is a printed circuit board 21 that is detachably connected to the housing cover. It supports the signal electronics.
A printed circuit board 23 having power electronics 27 is arranged in bottom part 26, the printed circuit board supporting a plug-and-socket connector for an electrical plug connection to a further plug-and-socket connector, the further plug-and-socket connector being connected to printed circuit board 21. Power electronics 27 are connected to bearing support 1 in a thermally conductive manner. For this purpose, the bearing support has a precision-machined surface that may be used as a contact surface. Heat-conduction paste may also be added to improve the heat-transfer resistance.
Therefore, bearing support 1 is manufactured to be a multifunctional part. Thus, it not only has the above-mentioned mechanical interfaces, but is also used for discharging the heat of the power electronics to the environment. To improve this dissipation of heat, it may be provided that the fan additionally and actively supplies the bearing support with cooling air from the environment. Consequently, not only the stator of the electric motor, but also power electronics 27 may be cooled.
The signal electronics and power electronics are manufactured together as a converter. Consequently, the stator of the electric motor may be powered by this converter, and the entire electric motor is thus controllable from the converter. The converter may be powered by three-phase current.
The power electronics include at least the rectifier and the output stage controllable in a pulse-width-modulated manner, i.e., the inverter, which generates, from the rectified voltage, an a.c. voltage having a frequency predefined by the control electronics. The corresponding electronic circuit breakers give off the heat generated by them to a support, which is connected to bearing support 1 in a thermally conductive manner. The support is mechanically connectible to the bearing support, e.g., in a force-locked manner.
The power electronics may be connected to the cover in a thermally conductive manner, the cover having a contact surface suitable for heat transfer.
The same stator with housing 15 is illustrated in
Fan-hood grating 32 may be manufactured to be substantially identical to fan-hood grating 19 illustrated in
Labyrinth seal 33 and shaft sealing ring 34 allow manufacturability with a high degree of protection, e.g., at least IP65. Labyrinth seal 33 makes a seal between the bearing support and the rotating fan, the occurring friction losses being very small. Shaft sealing ring 34 may improve the sealing function considerably. The one-piece formation of the bottom part of a terminal box may allow a high degree of imperviousness and protection to be achieved in a cost-effective manner, using simple arrangements.
Another variant is illustrated in
A series of electric motors is provided, which allows different variants to be produced as a function of the application of the motor, where, however, as many parts as possible are reusable within this modular system. For example, the same stator, together with housing 15, is connectible to different bearing supports, a first bearing support including a brake and a fan, and a second bearing support only including a fan. In addition, the first bearing support is connectible, with the aid of its upwardly directed interface, to a terminal box, i.e., connection box, or to a converter or to a different electronic device.
Illustrated in
An alternative bearing support 63 is illustrated in
Provided for mounting a sensor are knockouts 62, which may be manufactured inexpensively and are easily removable during the mounting.
Spatial, oblique views from the front and back, which belong to bearing support 63 illustrated in
Spatial, oblique views from the front and back, which belong to bearing support 30 illustrated in
As illustrated in
An electric motor, which is manufactured to be similar to the one illustrated in
An electric motor, which is manufactured to be similar to the one illustrated in
The sensor may be directly mounted to printed circuit board 23, and the printed circuit board may be able to be positioned very accurately. Therefore, this arrangement directly allows the sensor to detect the alternating direction of magnetization at the fan. Information regarding the rotational speed and direction of rotation may be derived from the sensor signals. This allows the electric motor to be controlled and/or regulated in an improved manner.
The signal electronics and power electronics may not take the form of a converter, but rather a soft-start device, i.e., starter. This allows costs to be reduced.
As an alternative, the signal electronics and power electronics may be arranged as a switch for switching the motor on and off, the switch being able to be implemented electromechanically or electronically.
Other motor electronics may also be provided as signal electronics and power electronics. For example, the motor electronics may be arranged as a voltage-adjustment module for the motor and/or the brake, or as a broad-voltage module for the motor and/or the brake.
At least a part of the power electronics may be connected to the cover in a thermally conductive manner. To this end, the inner side of the cover may be machined such that the heat from the power electronics may be transferred to it. This connection may be implemented in a force-locked manner. However, other types of connections may also be provided.
The signal electronics may also include powerline electronics. This means that the electronic circuit is able to modulate information onto the supply lines, e.g., power cables, using, in particular, a frequency much higher than, e.g., 50 Hz. For example, frequencies between 10 kHz and 10 MHz may be suitable.
The bearing support may be formed of diecast aluminum. However, it may be provided to make the bearing support out of thermally conductive ceramic. Therefore, a low-wear friction surface may be provided for the brake, the heat of the friction surface generated during braking being able to be removed quickly and easily from the bearing support.
It is also possible to make only the friction surface out of ceramic.
The bearing support may also be made of cast iron, e.g., gray cast iron.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 016 781 | Apr 2004 | DE | national |
| 10 2004 033 745 | Jul 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2005/001732 | 2/18/2005 | WO | 00 | 10/2/2006 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2005/107042 | 11/10/2005 | WO | A |
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