Fan wheel and electric motor

Abstract

fan wheel, wherein a guide ring (3) on the circumference reduces air vortex flows, wherein a first track (4) of alternately magnetized material and at least one second track (5) of alternately magnetized material are arranged on the outside of the guide ring (3), wherein the number of actively magnetized permanent magnet areas is greater than the number of fan blades (1), wherein at least the two tracks (4, 5) are provided on the circumference of the fan wheel for detecting the direction of rotation and the angle of rotation, where the magnetization of the regions is oriented in the radial direction, wherein the alternately magnetizable material is connected to the circumference as an elastic pole wheel which is pushed onto the fan wheel and then holds itself force-locked to the circumference, wherein the alternately magnetizable material consists of ferrite particles mixed into plastic.

Description

[0001] The invention relates to a fan wheel and an electric motor.

[0002] Electric motors with fans are commonplace. The fan drives an airflow that flows along the housing of the electric motor, thus improving heat dissipation. It's also common to connect the fan to the rotor, so that when the rotor is stationary, the fan also stops.

[0003] An example of this is DE 295 14 026 U1, in which a sensor detects fan blades to generate information about the speed of the rotor.

[0004] EP 1058120 A1 also discloses a fan which has a track of sensor flags on its circumference to generate such information.

[0005] From DE 15 13 293 A, an asynchronous motor is known as the closest prior art.

[0006] A magnetic rotary encoder is known from DE 29 08 599 A1.

[0007] The arrangement for determining the position of a body is known from DE 102 28 663 A1.

[0008] From US 4 599 561 A an arrangement for detecting the relative and absolute position of a moving body is known.

[0009] The invention is therefore based on the object of developing an electric motor, wherein the control quality of a converter supplying the electric motor can be improved.

[0010] According to the invention, the object is achieved with the fan wheel according to the features specified in claim 1 and with the electric motor according to the features specified in claim 3.

[0011] Essential features of the invention in the fan wheel are that at least one track of alternately magnetized material is provided on the circumference of the fan wheel.

[0012] The advantage here is that the fan itself can be designed as a high-precision angle sensor and has actively magnetized permanent magnet areas around its circumference, meaning it can be detected by a sensor and a very good signal-to-noise ratio can be achieved.

[0013] Furthermore, the moment of inertia of the rotor, including the fan and sensor, is very low overall. This is because no additional axially arranged sensor is necessarily connected to the rotor. In the invention, the fan wheel itself is designed as a high-precision sensor. The sensor can be easily attached to the surrounding housing.

[0014] According to the invention, a guide ring is provided on the circumference, particularly to reduce air turbulence. An advantage here is that the surrounding housing can also be designed with a square shape.

[0015] In an advantageous embodiment, the alternately magnetizable material is glued on as a tape. This is advantageous because it is inexpensive and easy to manufacture.

[0016] According to the invention, the alternately magnetizable material consists of ferrite particles mixed into plastic. The advantage of this is that its production is very simple and cost-effective.

[0017] According to the invention, at least two tracks are provided on the circumference of the fan wheel, in particular for detecting the direction of rotation and the angle of rotation. This advantageously allows for the implementation of a sensor with a high angular resolution.

[0018] According to the invention, the alternately magnetizable material is connected to the circumference as a magnet wheel, particularly in an elastic design. This is advantageous in that it can be easily slid onto the circumference during production and then holds itself firmly to the circumference.

[0019] Key features of the invention for the electric motor are that it comprises a rotor and a fan wheel connected to the rotor, wherein a sensor is provided on a housing part of the electric motor, in the sensitivity range of which magnetized areas of the fan wheel are located, in particular for determining the angle of rotation or rotational speed of the fan wheel. The advantage here is that the angle sensor including the sensor is integrated in the motor and therefore does not require a separate housing. In particular, the fan can be used as a high-precision sensor. A particular advantage here is that the resolution can be higher than when using the fan blades for detection. The resolution is independent of the number of fan blades and is determined solely by the number of areas magnetized in different directions.

[0020] In an advantageous design, the air ducts are enclosed in the housing section forming the B-end shield, and this deviates from the circular shape on the inside. This is advantageous because large ducts can be realized. Furthermore, there is space for mounting screws for the motor housing, which would not be available with a circular design.

[0021] In an advantageous embodiment, at least one sensor for detecting the magnetization direction is provided on the B-end shield in such a way that pulses can be generated when the fan wheel rotates. Advantageously, the sensor can be integrated into the motor and, in particular, located close to the terminal box, allowing its connecting cables to be easily routed out and connected to devices that can be connected there, such as a converter supplying the motor.

[0022] In an advantageous embodiment, at least one sensor for detecting the magnetization direction is provided on the B-end shield, allowing the direction of rotation to be detected when the fan wheel rotates. This advantageously incorporates a high-precision angle sensor without additional effort and without increasing the rotor's moment of inertia. Furthermore, the inverter supplying the motor can be supplied with all the angular position, angular direction, and / or angular velocity information necessary for controlling the motor. Further advantages are set out in the subclaims.

[0023] The invention will now be explained in more detail with the aid of illustrations: In the Fig. 1 shows a fan wheel according to the invention, which has fan blades 1 and a guide ring 3 on its outermost circumference. On its inner circumference, the fan wheel has a connection point 2 to a shaft, which is designed to be form-fitting.

[0024] If the fan impeller is mounted in a hollow body that doesn't have a circular inner boundary, such as a hollow cuboid, air turbulence can occur, impairing the effectiveness of the cooling airflow. The advantage of the guide ring is that it reduces turbulence in the space surrounding the fan impeller.

[0025] The guide ring is provided with a first track 4 and a second track 5, each consisting of areas of material magnetized in different directions. This allows not only the rotational speed to be detected, but also the direction of rotation to be detected.

[0026] The detecting sensor is located on the surrounding housing part. Preferably, two sensors are assigned to each track.

[0027] In the simplest way, to produce the magnetizable areas, ferrite material is added to the plastic during the injection molding of the guide ring. After the guide ring is manufactured, especially together with the fan wheel in a single operation, the magnetization of the areas is carried out. Fig. 1 black colored areas with north pole direction radially outwards and the white colored areas with north pole direction radially inwards.

[0028] In further embodiments according to the invention, a magnetized region with a length different from the usual period length is provided at a specific location on the circumference of the first track 4. Thus, a zero angle position can be identified and the angle determined.

[0029] In further embodiments according to the invention, the guide ring is also provided on a circumference of the fan wheel at a radially smaller position, i.e. between the outer and the inner circumference.

[0030] In further embodiments of the invention, the tracks made of magnetizable material are glued to the guide ring by means of a tape.

[0031] In other embodiments according to the invention, a flexible ring made of magnetizable areas is pushed onto the fan wheel and thus at least partially forms the guide ring 3.

[0032] In Fig. 2a shows a motor according to the invention which has a motor housing 21 to which a bearing shield housing 22 is connected on the B-side, on which the terminal box 20 is provided.

[0033] A sensor 23 is provided on the bearing shield housing such that at least one track (4, 5) is located within its sensitivity range. This allows signals, particularly pulse-shaped signals, to be generated when the fan wheel rotates.

[0034] Preferably, in other embodiments of the invention, two sensors are mounted next to each other, each of which is assigned to one of the tracks.

[0035] The inner surface surrounding the fan wheel is not circular, but square.

[0036] The air ducts 24 are larger, particularly in the area of ​​these corners, and without the guide ring, turbulence could occur, which would impair the cooling overall.

[0037] The cooling air flow exits the air ducts in such a way that it passes the housing of the electric motor, thus improving the heat dissipation from the housing to the environment. List of reference symbols 1 fan blade 2 Connection point to the rotor 3 Guide ring 4 first track 5 second lane 20 junction box 21 Engine housing 22 bearing shield housing 23 Sensor 24 air duct

Claims

[1] Fan wheel, wherein a guide ring (3) on the circumference reduces air vortex flows, wherein a first track (4) of alternately magnetized material and at least one second track (5) of alternately magnetized material are arranged on the outside of the guide ring (3), wherein the number of actively magnetized permanent magnet areas is greater than the number of fan blades (1), wherein at least the two tracks (4, 5) are provided on the circumference of the fan wheel for detecting the direction of rotation and the angle of rotation, where the magnetization of the regions is oriented in the radial direction, wherein the alternately magnetizable material is connected to the circumference as an elastic pole wheel which is pushed onto the fan wheel and then holds itself force-locked to the circumference, wherein the alternately magnetizable material consists of ferrite particles mixed into plastic. [2] Fan wheel according to claim 1,characterized by that the connection is intended to be force-fitting, form-fitting or material-fitting. [3] Electric motor, comprising a rotor, a fan wheel connected thereto according to claim 1 or 2, wherein a guide ring (3) on the circumference of the fan wheel reduces air swirl flows, the magnetized areas are provided on the outside of the guide ring (3), where the magnetization of the regions is oriented in the radial direction, wherein a sensor (23) is provided on a housing part of the electric motor, in the sensitivity range of which the magnetized areas of the fan wheel are located, wherein a device is connectable to the sensor (23) which determines the angle of rotation or the speed of rotation of the fan wheel and the rotor of the electric motor connected thereto. [4] Electric motor according to claim 3, characterized by that the device is an inverter that supplies the motor. [5] Electric motor according to claim 3 to 4, characterized by that air ducts are enclosed by the housing part forming the B-bearing shield and that this deviates from the circular shape on the inside. [6] Electric motor according to at least one of claims 3 to 5, characterized by that at least one sensor (23) for detecting the magnetization direction is provided on the B-bearing shield in such a way that pulses can be generated when the fan wheel rotates. [7] Electric motor according to at least one of claims 3 to 6, characterized by that at least one sensor (23) for detecting the direction of magnetization is provided on the B-bearing shield in such a way that the direction of rotation can be detected when the fan wheel rotates.

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