The present invention relates to a connecting plate for an electric motor and to an electric motor.
Particularly in some electrically commutated motors with a magnetic rotor or a permanent magnet in the rotor, one or more sensors are provided which are used to detect the position of the rotor relative to the stator field. This variable is essential in order to be able to control the stator currents as a function of the rotor position, thereby enabling maximum motor torque to be achieved.
These sensors and the necessary electrical components are generally provided on a small printed circuit board which will hereinafter also be referred to as a PCB. This PCB or more specifically the sensors on the PCB are mounted between the stator teeth, i.e. the stator poles, in order to be able to detect the magnetic field of the rotor magnets. Alternatively, the PCB is provided with the sensors on the end shield in plastic holders specially provided for the purpose in order to detect the field of an additional magnetic ring provided on the shaft outside the motor or more specifically the motor housing. In both cases the sensors provided on the PCB must be connected to control electronics elements via relatively long connecting lines.
The disadvantage of the known solutions is that large tolerances in detecting the rotor position must be accepted. In addition, a large number of motor parts are required. For example, in particular the holders for the sensors and corresponding fixing screws must be provided.
The object of the invention is to eliminate these disadvantages and in particular provide a motor component of simple construction.
The invention is based on the recognition that this object can be achieved by extending the functionality of a component generally provided in an electric motor.
This object is thus achieved according to a first aspect by a connecting plate for an electric motor, said connecting plate being characterized in that it has at least one mounting area with at least one mounting hole for at least one sensor for monitoring the rotor position.
Within the scope of this invention, the connecting plate, which will hereinafter also be called the terminal, refers to the internal terminal plate via which the wires of the stator windings can be connected. Said internal connecting plate may comprise an external terminal to which the external lines are connected or it can be connected thereto via a plug-in connection. The inventive implementation of the connecting plate means that it can be used both for contacting the coil windings and as a support and fixing for sensors. Incorporation of the sensor holder in the connecting plate obviates the need for a separate sensor holding device which would generally required screws and other components. The mounting hole in the mounting area can be used in particular for guiding the sensors through it. In addition, the mounting holes can be provided with a flange or web which protects the sensor guided through the mounting hole at least from one side.
By providing at least one mounting hole in the connecting plate and the sensors being able to point to the side facing away from the mounting area, lines can be routed from the sensors or rather from the PCB to contacts and/or control electronics on the side of the connecting plate facing away from the sensors and therefore the stator. This means that the PCB can be protected by an end shield provided on the motor.
According to one embodiment, the mounting area has at least one recess for accommodating a printed circuit board. This printed circuit board (PCB), which can be used for contacting the sensors and can also carry sensor system elements, can therefore be retained in a protected position and the position of the PCB can be predetermined by the recess.
The connecting plate is preferably L-shaped, there being provided in one leg at least the mounting area and in the other leg at least the contacts for connecting or more specifically contacting the coil windings of the electric motor. In this way the contacts can be disposed on the edge of the stator where the connecting plate can be brought into direct connection, i.e. without wires, with an external terminal. In addition, the mounting area can extend over the end face of the stator, thereby enabling the sensors to be reliably positioned at the location at which they are to monitor or more specifically detect the position of the rotor.
On the leg in which the contacts are provided, there can be additionally provided at least one fixing element for attaching the connecting plate to the stator, in particular to the stator assembly. Said fixing element enables the connecting plate to be fixed directly to the stator and because of the incorporation of the sensor holder in the connecting plate therefore also allows the position of the sensors to be precisely defined. This type of connecting plate and its fixing to the stator enables rotor position detection tolerances to be eliminated.
The mounting area of the connecting plate preferably covers part of the circumference of the stator end face. In contrast to a device which covers the entire end face of the stator, this embodiment has a simplified construction. Material is only required to form the mounting area in which the PCB can be accommodated.
According to one embodiment, the mounting area holds a circuit board which has at least one contact plug for establishing contact with or connecting to the contacts of the connecting plate. This arrangement completely eliminates the need for separate connecting wires for the sensors which are likewise disposed on the PCB. In addition, only one type of connection is implemented in the entire component, as the stator windings can also be contacted via corresponding contact plugs.
Alternatively there can be provided in the mounting area at least one guide for a connecting line between a printed circuit board and the at least one contact. This guide can be implemented by partition walls in the recess of the mounting area. Connecting lines provided on the PCB can run in these guides and therefore be protected.
According to another aspect, the invention relates to an electric motor, in particularly a commutated electric motor, with a stator, a rotor and at least one sensor for detecting the rotor position. The electric motor is characterized in that it comprises at least one connecting plate having at least one mounting area with at least one mounting hole for the at least one sensor. The inventive connecting plate enables the electric motor to have a simpler construction than conventional electric motors. In particular, separate fixing devices for holding the sensors can be dispensed with.
According to one embodiment, the electric motor has a magnetic ring between the rotor and a bearing supporting an end shield. In the inventive embodiment of the motor, said magnetic ring used for monitoring the rotor position can be provided inside the motor housing, as the sensors are integral with the stator connecting plate. This mounting location of the magnetic ring reduces the overall length of the electric motor compared to conventional motors in which the magnetic ring is provided outside the end shield.
On the outer circumference of the stator assembly there is preferably provided in the electric motor according to the invention at least one fixing cutout for fixing at least one connecting plate. Said fixing cutout in particular constitutes a slot into which part of the connecting plate can be inserted, thereby fixing the stop of the connecting plate and therefore the position of the sensors.
Advantages and features described with reference to the connecting plate also hold true—where applicable—for the inventive electric motor and vice versa.
The present invention will now be explained again in detail with reference to the accompanying drawings in which:
As illustrated particularly in
As
The attachment of the connecting plate 1 to the stator arrangement 23 of an electric motor is shown in
The top view onto this embodiment of the electric motor 25 shown in
In the further embodiment shown in
With the present invention it is possible to achieve sensor positioning with minimal tolerances between the stator assembly and the motor end shield as well as between the motor end shield and plastic sensor holders. The invention permits minimal tolerance between the stator teeth, i.e. the stator poles, and the sensor or sensors. The invention also offers extremely short connecting lines for connecting the sensors to the contact area of the internal connecting plate. In addition, with the invention two functions can be incorporated in one motor component, namely the connecting plate function and the sensor holder function. No screws are necessary for fixing the sensor holder to the motor and, in addition, mechanical protection can be provided for the sensor holder, sensors and PCB by the motor end shield. The invention also allows a shorter shaft to be used for the motor, as a magnetic ring can be provided on a free section of the rotor shaft between the bearing and the rotor assembly. Lastly, the total number of motor connecting plates, contact types for motor connecting plates, screws for fixing the holder and plastic parts can be reduced by incorporating the sensor holder in the internal motor connecting plate.
Number | Date | Country | Kind |
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DE102005046759.8 | Sep 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP06/66823 | 9/28/2006 | WO | 00 | 4/29/2008 |