WO2016026596A1

WO2016026596A1 - Electric machine with integrated encoder structure

Info

Publication number: WO2016026596A1
Application number: PCT/EP2015/063699
Authority: WO
Inventors: Miguel Ruiz De Larramendi
Original assignee: Robert Bosch Gmbh
Priority date: 2014-08-18
Filing date: 2015-06-18
Publication date: 2016-02-25
Also published as: DE102014216367A1

Abstract

An electric machine (10) is proposed which has a rotor (20), which is mounted so as to be rotatable about an axis of rotation (18), and a stator (12), which has a multiplicity of stator windings (14) designed to generate a magnetic excitation field for driving the rotor (20). Furthermore, the electric machine (10) has a magnetic field sensor (34) which is arranged so as to be immovable relative to the stator (12), which magnetic field sensor is designed to generate, in response to a change in a magnetic field, a signal from which a rotor position and/or a rotor rotational speed can be determined. The electric machine is distinguished in particular by the fact that the rotor (20) has at least one opening (32) which extends parallel to the axis of rotation (18) and which is designed to generate a local magnetic field change which can be detected by the magnetic field sensor (34). It is thus advantageously possible for an encoder wheel to be omitted.

Description

description

Electric machine with integrated encoder structure

Field of the invention

The invention relates to the field of electrical machines, such as

Electric motors or generators. Background of the invention

Electrical machines are used in the form of synchronous machines or asynchronous machines in many areas of industry. In particular, electrical machines are increasingly being used in the automotive industry

Vehicles with electric or hybrid drive application and become this

Purpose further developed.

Electrical machines usually have a rotatably mounted in a stator rotor. For operation of the electric machine as a motor generated in the stator, rotating magnetic field or magnetic rotating field to the

Rotor applied and so a torque can be applied to this, by which the rotor can be set in rotation. Such electrical machines are therefore also referred to as induction machines. For a control of induction machines, in particular for hybrid and

Electric vehicles, it may be necessary to determine a current rotor position or an angular position of the rotor and / or a rotor speed. Electrical machines are therefore often equipped with an angle encoder system and / or a speed sensor system. Such systems for angle and / or speed detection, for example, a resolver and / or a

Have eddy current sensor. Also so-called digital encoder systems are used for angle and / or speed detection, which usually have a provided with a toothed encoder wheel of magnetically conductive material, such as iron or steel, which may be rotatably connected to the rotor. By means of at least one relative to the stator immovably arranged

Magnetic field sensors, such as a Hall sensor, can be local

Magnetic field changes detected and corresponding sensor signals are generated, which can allow determination of the rotor position and / or the speed.

A sender wheel of the type described above is known for example from DE 198 13 594 AI.

Disclosure of the invention

Embodiments of the present invention may advantageously enable to provide a compact, inexpensive and lightweight electric machine.

According to a first aspect of the invention, an electric machine, such as a synchronous machine or an asynchronous machine is proposed, which has a rotatably mounted about a rotation axis rotor and a stator having a plurality of stator windings, which are designed to a magnetic excitation field, such as a magnetic Rotary field, to power the

To produce rotor. Next, the electric machine has a relative to the stator immovably arranged magnetic field sensor. The magnetic field sensor is designed to generate a signal on a change of a magnetic field, from which a rotor position and / or a rotor speed can be determined. The rotor position may be about an angular position of the rotor. The electric machine according to the invention is characterized in particular in that the rotor has at least one opening which extends parallel to the axis of rotation and which is designed to generate a local magnetic field change, which is detectable by the magnetic field sensor.

In other words, the opening in the rotor can locally cause a change in a magnetic quantity, such as a magnetic flux density, a magnetic flux and / or a magnetic field strength, which can be detected by a passing of the opening on the magnetic field sensor of this. The magnetic field sensor may generate a signal in response to the detected magnetic field change that may be communicated to, for example, a processing device such as a controller. Based on the transmitted signal, the processing device can determine the rotor position and / or the rotor speed. For this purpose, the magnetic field sensor can also generate a digital signal which

For example, when exceeding or falling below a predefinable threshold value of a magnetic variable can be output from the magnetic field sensor. The electrical machine according to the invention can therefore have a so-called digital rotary encoder system, wherein the opening integrated in the rotor can serve as an integrated encoder structure.

By integrated in the rotor opening a separate encoder wheel for the electric machine can be omitted. This in turn can advantageously affect a weight, manufacturing costs and a size of the electric machine. Maintenance work can also be reduced.

According to an embodiment of the invention, the opening is closed in a radial direction of the rotor. The opening may have a triangular, a square, a round, a polygonal or any other shaped cross-section. The opening may be completely enclosed in the radial direction, such as in a rotor cross-section, such as components of the rotor. The opening may be a radial hole.

According to one embodiment of the invention, the rotor has a plurality of openings at the same radial distance from the axis of rotation, the local

Generate magnetic field changes detectable by the magnetic field sensor. The openings may, for example, along a

Circumferential direction may be arranged equidistant or at a variable distance from one another at a diameter of the rotor.

According to one embodiment of the invention, the magnetic field sensor is a Hall sensor. In particular, with regard to a component size and precision, a Hall sensor may be advantageous.

According to one embodiment of the invention, the magnetic field sensor is arranged on an end face of the rotor in the axial direction next to the opening. Of the Magnetic field sensor can thus detect a magnetic field or a magnetic field change in the axial direction. The magnetic field sensor can thus be arranged axiallesend. According to one embodiment of the invention, the opening is in a

Lamella package of the rotor introduced. The opening can be introduced, for example, by punching a portion of the disk pack in the disk set. By integrating the opening into the disk pack, a compact, cost-effective, lightweight and robust electric machine can be provided

to be provided.

According to one embodiment of the invention, the opening extends through the entire disk pack in a longitudinal direction of the

Plate pack. The longitudinal extension direction of the disk set can run parallel to the axis of rotation. By forming the opening in the entire disk pack, it can be ensured that the change in the magnetic field caused by the opening is large enough, even at high temperatures

Speeds can be detected with sufficient precision. Furthermore, such a configuration can simplify production and

Reduce production costs, since, for example, all the slats of the disk pack can be made identical and then joined together to form a disk pack.

According to an embodiment of the invention, the opening is arranged in a radial direction between a short-circuiting ring of a short-circuiting cage (ASM) or the largest circle around the shaft which does not contact the permanent magnets (PSM) and a shaft of the electric machine. The shaft can be arranged coaxially to the axis of rotation. An area between the

Short-circuit ring and the shaft is often referred to as Rotorjochbereich. The rotor yoke region is often not used electromagnetically, i. it is not used for generation of torque or otherwise, so that the opening can be arranged in this area without affecting further operation of the electric machine. The opening can also be partially covered by the short-circuit ring.

According to one embodiment of the invention, the opening is in one

Balancing disk of the rotor introduced, wherein the balancing disk is arranged on the front side of the rotor. The balancing wheel can for this purpose from a be made of magnetically conductive material, such as iron, steel and / or another ferromagnetic material. By integrating the opening in the balancing disk, a cost-effective, lightweight and compact electric machine can be provided.

According to one embodiment of the invention, the opening extends through the entire balancing disk in the longitudinal extension direction of the balancing disk. The longitudinal extension direction of the balancing disk can run parallel to the axis of rotation.

It should be understood that some of the possible features and advantages of the invention are described herein with reference to different embodiments. A person skilled in the art will recognize that the features can be suitably combined, adapted or replaced in order to arrive at further embodiments of the invention.

Brief description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which neither the drawings nor the description are to be construed as limiting the invention.

Fig. 1A shows a plan view of a frontal site of an electric machine according to an embodiment of the invention.

Fig. 1B shows a longitudinal section through the electric machine of Fig. 1A.

Fig. 2A shows a plan view of a frontal site of an electric machine according to an embodiment of the invention.

Fig. 2B shows a longitudinal section through the electrical machine of Fig. 2A.

The figures are only schematic and not to scale. Like reference numerals in the figures designate the same or equivalent

Characteristics. Embodiments of the invention

FIG. 1A shows a plan view of an end site of an electric machine 10 according to an embodiment of the invention. Fig. 1B shows a longitudinal section through the electric machine 10 of Fig. 1A. The electric machine 10 shown in Figs. 1A and 1B is an asynchronous machine.

The electric machine 10 has a substantially hollow cylindrical stator 12 with a plurality of stator windings 14, which along a

Circumference of the electric machine 10 are arranged. The stator windings 14 may extend substantially in a longitudinal direction of the electric machine 10. Further, the electric machine 10 has a shaft 16 around a

Rotary axis 18 rotatably mounted rotor 20. The rotor 20 may be arranged coaxially with the stator 12 and spaced therefrom by a gap 15. The rotor 20 has a disk set 22, which may have a multiplicity of substantially cylindrically shaped laminations 24 stacked one above the other in the longitudinal extension direction of the electric machine 10. In this case, each sheet metal plate 24 made of a ferromagnetic

Be punched out metal sheet.

Further, the rotor 20 along an outer periphery on a plurality of short-circuiting rods 26, which in complementary formed

Recesses of the rotor 20 are arranged and in

Longitudinal direction of the rotor 20 extend. The short-circuit bars 26 are electrically connected to a short-circuit cage 30 with an annular short-circuit ring 28 on each end face of the rotor 20 so that eddy currents can flow in the short-circuit cage 30.

Further, the rotor 20 along a circumference openings 32, which are arranged in the radial direction of the rotor 20 (orthogonal to the axis of rotation 18) between the shaft 16 and the short-circuit ring 28. The openings 32 may be arranged in the so-called rotor yoke, wherein a distance of the

Openings 32 to the shaft 16 smaller or larger than a distance from the

Short circuit ring 28 can be. The openings 32 can also at least be partially covered by the short-circuit ring 28. It is also possible to provide a plurality of such openings, for example two or more.

The openings 32 may have an arbitrarily shaped cross-section, for example they may have a round, triangular, quadrangular,

have trapezoidal or polygonal cross-section. The openings 32 may have the same radial distance from the axis of rotation 18 or to the shaft 18. However, they can also be arranged at a variable distance from the shaft 18. Furthermore, they can be arranged equidistant or at variable spacing in the circumferential direction of the rotor 20.

The openings 32 are designed to be closed in the radial direction both toward the shaft 16 and towards the stator 14. In other words, the openings 32 are completely embedded in the disk pack 22 of the rotor 20 and surrounded by this, wherein a boundary of the openings 32 of the

Disc pack 22 can be defined. Two openings 32, which are directly adjacent to one another along the circumferential direction, are each separated from a partial area 33 of the lamella packet 22 in a spoke-like manner. It can thus be formed by the openings 32 a kind of tooth-gap geometry in the disk set 22, wherein the portions 33, the teeth and the openings 32 the

Can form gaps. The tooth-gap geometry may be considered as a donor structure integrated into the rotor 20 or a donor wheel integrated into the rotor 20. The openings 32, the disk set 22 of the rotor 20 in

Pull longitudinal direction of the rotor 20 completely or partially, in the latter case, at least as macroscopic depressions on at least one end face of the rotor 20 may be formed. A

Longitudinal direction of the openings 32 may extend parallel to the axis of rotation 18.

Furthermore, the electric machine 10 has a relative to the stator 12

immovably arranged magnetic field sensor 34, which is arranged on an end face of the rotor 20 in the axial direction adjacent to an opening 32. The magnetic field sensor 34 may be spaced apart in the axial direction at a distance of a maximum of ten mm, for example a maximum of one mm and in particular a maximum of 0.5 mm from a front-side outer surface of the rotor 20. The magnetic field sensor 34 has a sensor element 37, such as a Hall sensor. The magnetic field sensor 34 may further comprise a magnetic element 35, wherein the sensor element 37 between an end face of the rotor 20 and the

Magnet element 35 may be arranged. In other words, the magnetic element 35 may be arranged in the axial direction behind the sensor element 37. It is also possible for a plurality of magnetic field sensors 34 to be arranged at the same or variable radial distance on at least one end face of the rotor 20.

The magnetic field sensor 34 may be disposed at a substantially equal radial distance from the shaft 16 as the apertures 32, such that an outer surface of the magnetic field sensor 34 facing the rotor 20 may at least partially overlap the aperture 32 as it engages the aperture 32

Magnetic field sensor 34 is rotated past with the rotor 20.

Furthermore, the electric machine 10 has a processing device 36, which may be electrically connected to the magnetic field sensor 34 and may be configured to process a signal generated by the magnetic field sensor 34. The processing device 36 may be about a controller.

Are the stator windings 14 driven or by a current

flows through, so a magnetic excitation field, such as a magnetic rotating field, is generated for driving the rotor 20. The excitation field can

Induce eddy currents in the short-circuit cage 30 and concomitantly another magnetic field in the disk set 22, whereby in interaction with the excitation field, a torque exerted on the rotor 20 and this can be set in rotation.

The generated by the magnetic element 35 of the magnetic field sensor 34

Magnetic field can interact at least partially with the plate pack 22, wherein the introduced into the plate pack 22 openings 32 through the

Magnetic element 35 locally disturbing or may cause a local change in the magnetic field. "Local" may mean in this context "in a limited space around the openings 32 around". For example, the sensor element 37 can detect a relatively weak magnetic field when one of the openings 32 is arranged in the axial direction directly next to the sensor element 37, whereas that

Sensor element 37 can detect a relatively strong magnetic field when formed between two directly adjacent openings 32 Subregion 33 is arranged in the axial direction directly adjacent to the sensor element 37. Upon rotation of the rotor 20, the sensor element 37 can thus alternately detect a strong and a weak magnetic field. If, during a rotation of the rotor 20, one of the openings 32 moves past the magnetic field sensor 34, it can detect the magnetic field change caused by this opening 32 and transmit or send an electrical signal or response signal to the processing device 36. The response signal may, for example, be a threshold signal which, when a certain threshold value is exceeded or fallen short of

Magnetic field strength and / or a relative or absolute magnetic field change can be output. Alternatively or optionally, the magnetic field sensor 34 also outputs a signal when one between two directly

adjacent openings 32 formed portion 33 of the disk pack 22 past the magnetic field sensor 34. However, the signal may also be a continuous measurement of the magnetic field strength, which of the

Processing device 36 can be processed.

The processing device 36 can determine a position or angular position of the rotor 20 from such a response signal. Next, the

Processing device 36 of at least two response signals of

Magnetic field sensor 34, a rotational speed or a rotational frequency of the rotor 20 and / or determine a rotational speed. FIG. 2A shows a plan view of an end face of an electric machine 10 according to a further embodiment of the invention. FIG. 2B shows a longitudinal section through the electric machine 10 from FIG. 2A. The electric machine 10 shown in Figs. 2A and 2B is a synchronous machine. Unless otherwise described, the electric machine 10 of FIGS. 2A and 2B may have the same features and characteristics as the electric machine

10 of FIGS. 1A and 1B and vice versa.

In the electric machine shown in FIGS. 2A and 2B, magnetic members 38 are embedded in and arranged in the rotor 20 along a circumference near an outer diameter of the rotor 20. The magnetic elements 38 may be about permanent magnets. The magnetic elements 38 may be fully or partially through the plate pack 22 in the longitudinal direction of the Rotor 20 extend and be arranged substantially parallel to the axis of rotation 18.

A magnetic excitation field generated by the stator windings 14 can interact with a magnetic field of the magnetic elements 38, so that a

Torque applied to the rotor 20 and this can be set in rotation.

Further, an at least one end face of the rotor 20, a balance disk 40 is arranged, which is designed in particular to the rotor 20th

balance and / or can be machined to balance the rotor 20.

In the balancing disk 40 openings 32 are arranged analogously to the openings 32 of FIGS. 1A and 1B, which are designed to be a local

Magnetic field change of the magnetic field generated by the magnetic element 35 of the magnetic field sensor 34 to generate magnetic field, which is detectable by the magnetic field sensor 34 and the sensor element 37 of the magnetic field sensor 34. All of the structural features and characteristics of the apertures 32 of Figs. 1A and 1B may apply analogously to the apertures 32 of Figs. 2A and 2B. The openings 32 of FIGS. 2A and 2B may also extend through the disk pack 22 in addition to the balance disk 40. The openings 32 in the balancing disk 40 are in the radial direction both towards the shaft 16 and towards the stator 12

closed and two circumferentially directly adjacent openings 32 are separated from portions 33 of the balancing wheel 40 spoke-like.

The openings 32 can over an entire thickness or width of the

Balancing disk 40 may be formed in the longitudinal direction. The openings 32 may extend only to a certain depth in the balancing disk 40.

A determination of a rotor position and / or a speed using the

Openings 32, magnetic field sensor 34, and processing device 36 may be analogous to the determination described in FIGS. 1A and 1B.

In addition, it should be noted that terms such as "inclusive" do not exclude other elements, and terms such as "a" or "an" do not exclude a multitude have been described on one of the above embodiments, also in combination with other features of others described above

Embodiments can be used. Reference signs in the claims are not to be considered as limiting.

Claims

claims

Electric machine (10), comprising:

a rotor (20) rotatably mounted about an axis of rotation (18);

a stator (12) having a plurality of stator windings (14) adapted to provide a magnetic exciter field for driving the rotor

(20) to produce; and

a magnetic field sensor (34) arranged immovably relative to the stator (12) and configured to generate a signal in response to a change in a magnetic field, from which a rotor position and / or a rotor speed can be determined,

characterized in that

the rotor (20) has at least one opening (32) which extends parallel to the axis of rotation (18) and which is designed to be a local one

To generate magnetic field change, which is detectable by the magnetic field sensor (34).

Electric machine (10) according to claim 1,

wherein the opening (32) is closed in a radial direction of the rotor (20).

Electric machine (10) according to claim 1 or 2,

wherein the rotor (20) has a plurality of openings (32) at the same radial distance from the axis of rotation (18), the local

Generate magnetic field changes detectable by the magnetic field sensor (34).

Electric machine (10) according to one of the preceding claims, wherein the magnetic field sensor (34) is a Hall sensor.

Electric machine (10) according to one of the preceding claims, wherein the magnetic field sensor (34) at an end face of the rotor (20) in axial direction adjacent to the opening (32) is arranged.

6. Electrical machine (10) according to one of the preceding claims, wherein the opening (32) in a disc pack (22) of the rotor (20) is introduced.

7. Electrical machine (10) according to one of the preceding claims, wherein the opening (32) extends through the entire disk pack (22) in a longitudinal direction of the plate pack (22).

8. Electrical machine (10) according to one of the preceding claims, wherein the opening (32) in a radial direction between a

Short-circuit ring (28) of a short-circuit cage (30) and a shaft (16) of the electrical machine (10) is arranged.

9. Electrical machine (10) according to one of the preceding claims, wherein the opening (32) is introduced into a balance disk (40) of the rotor (20),

wherein the balancing wheel (40) is arranged on the front side of the rotor (20).

10. Electrical machine (10) according to claim 9,

wherein the opening (32) extends through the entire balance disk (40) in the longitudinal direction of the centering wheel (40).