CN115694018A

CN115694018A - Rotor for an electric machine, electric machine and method for producing such a rotor

Info

Publication number: CN115694018A
Application number: CN202210884439.XA
Authority: CN
Inventors: B·蒙齐; F·科普夫; U·斯塔克
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2021-07-26
Filing date: 2022-07-26
Publication date: 2023-02-03
Also published as: DE102021207999A1

Abstract

A rotor for an electrical machine, an electrical machine (12) and a method for manufacturing such a rotor, the rotor having a rotor body (11) with fastening faces (14) for permanent magnets (16) at its radial outer circumference (13); and has a rotor shaft (12) which passes through the rotor body in the axial direction (8), wherein the rotor body (11) is formed in one piece and in one piece with the rotor shaft (12).

Description

Rotor for an electric machine, electric machine and method for producing such a rotor

Technical Field

The invention relates to a rotor for an electric machine, as well as to an electric machine and a method for producing such a rotor according to the generic type of the independent claims.

Background

DE 10 2007 029 719 A1 discloses a rotor of an electric machine, in which the magnets are arranged in a magnet packet (Magnettaschen) of the rotor which is closed radially to the outside. The magnets of the rotor are fixed in the magnet package by means of molded clamping elements. The rotor body is composed of individual magnetic steel laminated cores, which are connected to one another axially, for example by means of a press-packing (Stanzpacketieren), and pressed onto the rotor shaft. The magnetic steel laminated core is punched by a plate with variable thickness and magnetism. The manufacture of the rotor body and its fastening on the rotor shaft is therefore relatively cumbersome and subject to large tolerances. Furthermore, such a rotor body is relatively heavy and has a large moment of inertia, since each individual magnetic steel laminated core is radially supported at the rotor shaft. These disadvantages should be eliminated by the solution according to the invention.

Disclosure of Invention

THE ADVANTAGES OF THE PRESENT INVENTION

In contrast, the device according to the invention and the method according to the invention, which have the features of the independent claims, have the following advantages: the integral design of the rotor body together with the rotor shaft makes it possible to dispense with the stamping and joining of the individual magnetic steel laminated cores. Thereby, the fastening face of the magnet is accurately positioned directly during the manufacturing process of the rotor. The diameter and shape of the circumferential surface of the rotor body, but also the outer diameter of the rotor shaft or its axial length, can be selected as desired by the integrated design of the rotor. Such a rotor can be produced significantly more precisely and more cost-effectively by reducing the component diversity.

Advantageous modifications and improvements of the embodiments specified in the independent claims can be achieved by the measures mentioned in the dependent claims. By forming the rotor body in one piece with the rotor shaft, large cavities can be formed inside the rotor body, as a result of which the weight of the rotor and thus the mass moment of inertia of the rotor can be reduced considerably. By forming the hollow space in the interior of the rotor body, the rotor as a whole can be formed considerably shorter. In this case, the cavity can be configured to be open at an axial end of the rotor body, so that the rotor bearing can be arranged completely inside the rotor body. The rotor shaft ends in the axial direction within the rotor body, so that the length of the rotor dispenses with an axial extension of the rotor shaft at the end of the rotor body. This makes it possible to produce a very compact electric machine which, owing to the hollow space inside the rotor body, has a significantly lower moment of inertia, as a result of which also higher rotational speeds can be achieved.

Due to the integral production method of the rotor, the driven element can also be integrally molded directly onto the rotor shaft without additional process steps. In this case, it is particularly advantageous to form the external toothing of the driven pinion on the rotor shaft, which external toothing interacts with a transmission wheel of the respective transmission unit, which transmission wheel is to be driven by the electric motor. In this case, the driven element is preferably arranged at the region of the rotor shaft which projects out of the rotor body at the end and is therefore axially opposite the interior hollow space of the rotor body.

For supporting the rotor, the rotor shaft has a first bearing seat at an inner first end of the rotor body and a second bearing seat at an opposite second end (which is arranged axially outside the rotor body). In this case, the driven element on the rotor shaft can be particularly advantageously formed axially between the second bearing block and the rotor body. The free end of the rotor shaft can thereby be mounted directly in a transmission unit interacting with the driven element.

Fastening surfaces for permanent magnets are formed on the rotor body at its outer circumference. Inside, the rotor body faces an inner face of a cylindrical side face shape that the cavity has. The rotor body is thereby formed annularly over a large part of its axial extent. An end wall is formed in an axial end of the rotor body, which connects a radial outer ring of the rotor body to the rotor shaft in a radially integrated manner. The radially outer fastening surface can therefore be positioned mechanically rigidly and stably in the relatively short axial region of the end wall in relation to the rotor shaft in a reliable manner by means of the integral production of the entire rotor. The hollow space can thereby extend over a larger axial region of the rotor body and can thereby also completely accommodate the first rotor bearing.

At the end wall, a signal generator element can be molded in a simple manner during production between the ring region and the rotor shaft, which can be detected by a corresponding sensor. In this case, the signal generator element is still formed integrally with the entire rotor, wherein the signal generator element is formed as an axially elevated surface element which can be detected, for example, by an inductive sensor. The signal generator surface can particularly advantageously be configured as a surface axially offset with respect to a standard horizontal plane of the end wall, wherein the signal generator element preferably likewise configures in its interior a cavity which in each case merges into a total cavity in the interior of the rotor body. A plurality of signal generator elements are arranged on the circumference of the rotor body, the axially raised surfaces of which alternate in a stepped manner in the circumferential direction with the standard horizontal surfaces of the end walls. Preferably, the number of horizontal plane alternations between the signal generator element and the standard horizontal plane of the end face exactly corresponds to the number of permanent magnets arranged on the fastening face.

In another embodiment, the driven element is arranged at the outermost free end of the rotor shaft, and a second bearing seat for a second rotor bearing is arranged axially between the driven element and the end wall. In this embodiment, the outer diameter of the bearing seat is larger than the outer diameter of the driven member. Thereby, the second rotor bearing can be pushed axially through the driven element onto the second bearing block. In such an embodiment, the rotor can be mounted, for example, in a bearing shield or in a web of the stator, and the driven element projects axially from the stator for interaction with a corresponding transmission component.

In a preferred embodiment, the rotor has so-called "permanent magnets of the elongated-bar-type" which are mounted on the fastening surface. The fastening surface is preferably configured as a flat rectangular surface against which the corresponding flat contact surface of the permanent magnet rests in the form of a surface. The permanent magnets can be glued or pressed radially from the outside onto the fastening surface by means of a fastening sleeve, for example. In this case, positioning elements which are integral with the rotor body can also be formed between the respective fastening surfaces with reference to the circumferential direction in order to adjust the permanent magnets. Preferably, the rotor body has exactly 10 fastening surfaces, to which exactly 10 permanent magnets are fastened in total, which are in particular configured as rare-earth magnets.

In order to integrally form the rotor, such a rotor is produced from a sintered metal, which is introduced into a corresponding mold. In this case, the fastening surface, the end wall, the rotor shaft and optionally also the driven element and the signal generator element can all be integrally formed together as a single sintered component. In this case, the sintered metal is preferably magnetically permeable, so that the permanent magnets form a magnetic circuit via the rotor body. The permanent magnets are preferably magnetized in a radial direction, wherein the N and S poles alternate in each case over the circumference.

The integral rotor according to the invention can be inserted as an inner rotor into a stator, which preferably has a single-tooth coil as an electrical winding. Such a stator coil is electronically commutated, as a result of which the rotor is set in rotation by its magnetic poles in order to provide a torque at the driven element.

It is particularly advantageous if the stator housing can be matched to a cavity in the rotor body. In this case, a central axial extension is formed on the bottom side of the stator housing, which extends into the cavity of the rotor body. Here, the rotor bearing is supported at an axial extension, into which the end of the rotor shaft is inserted inside the cavity. By arranging the first rotor bearing axially inside the rotor body, the axial installation space of the electric machine can therefore be significantly reduced. If the stator housing is produced by drawing, the axially extending portion can be produced by drawing directly integrally with the bottom surface of the stator housing. The bearing receptacle into which the outer ring of the rolling bearing or the plain bearing can be inserted is then preferably shaped as an annular, bent double-layer plate at the axial extension. The entire bottom surface, including the axial extension, is designed as a closed plate, so that no moisture or dirt can penetrate into the stator housing.

The axially opposite sides of the rotor are preferably mounted in a transmission unit, which is flanged to the open side of the stator housing. Alternatively, the rotor can also be mounted in a bearing shield or in a web (which is part of the stator). A signal generator element is formed at the axial outer side of the end wall, which signal generator element can be detected by a sensor, which is preferably arranged at the bearing end cap and/or at a connecting plate. In particular, the sensor can advantageously surround the rotor shaft in an annular manner and is advantageously arranged axially opposite the signal generator element. If the sensor is configured as an inductive sensor, this inductive sensor is able to detect different axial levels between the signal generator element and the peripheral region between which the end wall is situated. Such a rotor position sensor can provide a signal for electronic commutation of the EC motor, or can also determine the position of the movable component to be adjusted by means of the gear unit. Furthermore, the rotational speed of the driven element can also be detected.

The inventive production of the rotor by sintering makes it possible to dispense with the complex punching of the laminated magnetic steel core and the combination thereof and the assembly thereof on the rotor shaft. Thereby, the different functional elements of the rotor can be constructed in a sintering die in a single process step. In this way, separate production of the output pinion or the signal generator element can be dispensed with, as a result of which the assembly effort can also be significantly reduced and a precise positioning of these functional elements and the fastening surfaces for the magnets at the rotor can be ensured. In addition to the sintering of the rotor body with the end wall and the rotor shaft, the signal generator element and/or the driven pinion are optionally integrally and integrally molded together on the rotor. Thereafter, it is only necessary to fasten separately manufactured permanent magnets to the fastening face of the rotor body.

Drawings

Embodiments of the invention are illustrated in the drawings and set forth in detail in the following description. Wherein:

figure 1 shows an embodiment of the electrical machine according to the invention,

figure 2 shows the rotor according to figure 1 without magnets,

FIG. 3 shows another embodiment of a rotor, an

Fig. 4 shows a further exemplary embodiment of the electric machine in the completely assembled state of the brake assembly.

Detailed Description

The electric machine 100 shown in fig. 1 is an electronically commutated electric machine. The electric machine 100 is designed with the rotor 10 as an inner rotor and comprises a stator 60, the stator base of which is inserted into a stator housing 61 (einfugen). Stator 60 has a plurality of radial stator teeth 76 distributed over its circumference, around which stator teeth energizable stator coils 71 are wound as electrical windings 72. For this purpose, at least one insulating cover 78 is arranged on the stator base body, which preferably consists of the individual axially stacked magnetic steel laminated cores 75. The stator coil 71 is then wound onto this insulating cover 78 by means of winding wire. All stator coils 71 can be completely wound with a single uninterrupted winding wire, for example. Alternatively, individual stator segments can be wound with individual winding wires. The stator coils 71 are designed as single-tooth coils, which are each wound around only a single stator tooth 76. A connecting plate 74 is arranged axially above the stator coil 71, which connecting plate electrically connects the stator coil 71 to an electronics unit for commutation of the stator coil 71. The stator housing 61 is designed as an open pot, at the open side 63 of which the gear unit 80 can be flanged to the housing flange 50. A bottom surface 62 is formed on a side 59 of the stator housing 61 opposite the open side 63, said bottom surface axially closing the stator housing 61 on this side 59. A bearing receptacle 65 for the first rotor bearing 21 is formed in the center of the bottom 62, in which the rotor shaft 12 of the rotor 10 is received in the axial direction 8.

The rotor 10 has a rotor body 11, which is arranged on the rotor shaft 12. At the radial outer circumference 13 of the rotor body 11, an n-sided circumferential surface 17 is formed, which is formed by the respective fastening surfaces 14, at which permanent magnets 16 interacting with the stator coils 71 are arranged. The rotor body 11 has, opposite the permanent magnets 16 in the radial direction 7, an inner face 18 in the shape of a cylinder side, which forms a cavity 20 in the interior of the rotor body 11. Here, the cylindrical, lateral inner surface 18 is arranged at a radial distance 19 from the rotor shaft 12, which extends with a first end 51 in the axial direction 8 into the cavity 20. The rotor shaft 12 is connected to the rotor body 11 via an end wall 26 (which extends in the radial direction 7 at the axial end region 15 of the fastening surface 14). The rotor body 11 is formed integrally with the end wall 26 and the rotor shaft 12 as a one-piece component, which is preferably formed as a magnetically conductive sintered component. An axial extension 64 is formed at the bottom 62 of the stator 60, which extends in the axial direction 8 into the cavity 20 of the rotor body 11. The bearing receptacle 65 for the first rotor bearing 21 is formed at the axial extension 64, which is preferably formed directly by a deep-drawn part of the stator 60 as a double-plate ring 67. The first rotor bearing 21 is designed, for example, as a rolling bearing, the outer ring of which is inserted directly into the bearing receptacle 65 and the inner ring of which accommodates the first bearing seat 21 of the rotor shaft 12. The first rotor bearing 21 is therefore arranged completely within the rotor body 11, in particular in the axial direction.

Fig. 2 shows the rotor 10 from fig. 1 without the permanent magnets 16 in a perspective view. The first end 51 of the rotor shaft 12 is designed to be axially shorter than the axial extent of the circumferential surface 17 of the n-side. The n-sided circumferential surface 17 has, for example, exactly 10 flat fastening surfaces 14 for the permanent magnets 16, which are of a rectangular design in particular. Then, exactly 10 permanent magnets 16 can be fastened to these fastening surfaces 14, in particular, with flat magnet sides (for example, with a retaining ring and/or with an adhesive material). Radial positioning elements for the permanent magnets 16 can optionally also be formed at the edge 57 between the fastening surfaces 14. The rotor body 11 is connected at its cylindrical inner surface 18 at the axial end region 15 of the fastening surface 14 via the end wall 16 to the rotor shaft 12. The inner surface 18 of the cylindrical lateral shape and the end wall 16 form a cavity 20 which is open axially toward the bottom surface 62. At the end wall 26, a signal element 28 is formed, which extends from a standard horizontal plane 30 of the end wall 26 in the axial direction 8 toward a second end 52 of the rotor shaft 12. Thus, the signal elements 28 alternate with peripheral regions 29 of a standard horizontal plane 30 along the circumferential direction 9. The signal element 30 is preferably of hollow internal design and therefore forms an axial offset 36 of the end wall 26. As a result, the signal elements 28 can be produced together with the end wall 26 without additional effort during sintering of the overall monolithic rotor 10. The signal element 28 of the rotor 10 interacts with a sensor 66 fastened to the stator 60. The sensor 66 is preferably fastened to the connecting plate 74 or to the bearing end cap and is in particular configured as a circumferentially closed ring which is arranged axially opposite the signal element 28. The sensor 66 is configured in fig. 1 as an inductive sensor, which is able to detect different axial distances relative to the signal element (compared to the reference horizontal plane 30 of the end wall 26). The number of signal elements 28 arranged on the circumference corresponds in particular to half the number of permanent magnets 14. In this case, the sensor 66 provides a rotor position signal which can be used for electronic commutation of the stator coil 71 and/or for position detection of the component to be adjusted.

In fig. 2, the driven pinion 24 is axially disposed between the end wall 26 and an axial second end 52 of the rotor shaft 12. In this case, the external toothing 23 of the driven pinion 24 is in particular also formed as a sintered component in a single piece with the integral rotor 10. At the free second end 52 of the rotor shaft 12, a second bearing block 32 is formed, which (as shown in fig. 1) is inserted axially into the second rotor bearing 22. In the configuration according to fig. 1, the second rotor bearing 22 is arranged in a transmission element 80, which is preferably flanged onto the open side 63 of the stator housing 61. The second rotor bearing 22 can be embodied, for example, as a slide bearing which is mounted in a drive wheel 82 which meshes with the output pinion 24.

Fig. 3 shows a variant of the rotor 10 according to fig. 2, in which the driven pinion 24 is arranged axially completely outside the second end 52 of the rotor shaft 12. The external toothing 23 of the driven pinion 24 is still formed integrally with the rotor shaft 12 and the rotor body 11 as a sintered component. Here, the second bearing block 32 is arranged axially between the pinion 24 and the end wall 26. For this purpose, the rotor shaft 12 has a larger outer diameter 34 at this point than the outer diameter 25 of the driven pinion 24. As a result, the rotor 10 can be inserted into the second rotor bearing 22 in the axial direction 8 without interfering with the output pinion 24. In this case, the second bearing block 32 or the rotor shaft 12 can extend directly in the radial direction 7 to the signal element 28 or have a radial distance from the signal element 28. It is also possible to arrange the sensor 66 in the stator 60 radially opposite the signal element 28. The permanent magnets 16 are designed here, for example, as bar-type magnets (brootiab-magnet) which can be held on the rotor body 11, in particular, by a centrifugal retaining sleeve (not shown).

As an alternative example of the electric machine 100, fig. 4 shows a fully assembled brake assembly 102 in which the electric machine 100 is bolted at a first side of the hydraulic assembly 90 by means of the flange 50. An electronics housing 92 with electronics units is arranged at the opposite side. From the hydraulic aggregate 90, an actuator 88 projects transversely to the axial direction 8, which is actuated by a hydraulic pump. Furthermore, a tank 94 for hydraulic fluid is arranged laterally to the hydraulic aggregate 90, said tank supplying the hydraulic pump with hydraulic fluid. In this case, the hydraulic pump is driven by the output element 24 of the electric motor 100. The electrical machine 100 has a rotor 10 in which the rotor body 11 is formed in one piece with a rotor shaft 12 and a first rotor bearing 21 is arranged in a cavity 20 inside the rotor 10. This allows a significantly shorter construction of the electric machine 100.

It should be noted that the embodiments shown in the figures and in the description enable various combinations of features with one another. Thus, for example, the specific configuration of rotor body 11 and the number of permanent magnets 16 can be varied according to customer requirements. Likewise, it is possible to match the configuration and position of the first and second bearing blocks 31, 32, the configuration and position of the driven pinion 24, and likewise the layout of the first and second rotor bearings 21, 22 with the corresponding stator 60 and transmission unit 80. The shape of the signaling element 28 can vary depending on the sensor 66 layout. In this case, at least two or more of the following functional combinations can be produced jointly in one piece in a single sintering tool: rotor shaft 12, rotor body 11, end wall 26, driven pinion 24, signal element 28, bearing seats 31, 32. The present invention is particularly suited for use in the construction of a brake assembly 102 in a motor vehicle, but is not limited to such an application.

Claims

1. Rotor (10) for an electric machine (12), having a rotor body (11) which has fastening surfaces (14) for permanent magnets (16) at its radial outer circumference (13); and has a rotor shaft (12) which passes through the rotor body (11) in the axial direction (8), wherein the rotor body (11) is constructed integrally and integrally from the same material as the rotor shaft (12).

2. The rotor (10) as claimed in claim 1, characterized in that the rotor body (11) has an inner face (18) in the shape of a cylinder side face and a cavity (20) is formed between the inner face (18) and the rotor shaft (12), wherein the cavity (20) is open-structured at an axial side of the rotor body (11), wherein in particular the rotor shaft (12) within the cavity (20) does not extend with a first end (51) in the axial direction (8) beyond the inner face (18), wherein a first rotor bearing (21) for supporting the rotor shaft (12) can be inserted axially into the cavity (20).

3. The rotor (10) according to claim 1 or 2, characterized in that a driven pinion (24) is integrally and monolithically constructed on the rotor shaft (12), which is arranged opposite to the first end (51) of the rotor shaft (12) outside the cavity (20).

4. The rotor (10) as recited in any one of the preceding claims, characterized in that a second bearing seat (32) for a second rotor bearing (22) is configured at a second end (52) opposite the first end (51), and in particular the driven pinion (24) is arranged axially between the second bearing seat (32) for the second rotor bearing (22) and the cavity (20).

5. Rotor (10) according to one of the preceding claims, characterised in that the rotor body (11) has an end wall (26) which connects the inner face (18) with the rotor shaft (12), and in that the end wall (26) is configured at an axial end region (15) of the fastening face (14), which end wall is opposite the open side of the rotor body (11).

6. Rotor (10) according to one of the preceding claims, characterized in that a signal element (28) for rotor position detection is arranged at the end wall (26), which signal element can interact with a sensor (66) arranged in the stator (60).

7. The rotor (10) as claimed in one of the preceding claims, characterized in that the signal elements (28) are constructed integrally with the end wall (26) as axial material elevations which alternate along the circumferential direction (9) with peripheral regions (29) of different material level material heights (30) of the end wall (26).

8. The rotor (10) of any one of the preceding claims, wherein a second bearing seat (32) is axially disposed between the driven pinion (24) and the end wall (26) and has an outer diameter (34) that is greater than an outer diameter (25) of the driven pinion (24).

9. The rotor (10) according to one of the preceding claims, characterised in that the fastening face (14) is configured as n flat rectangles constituting an n-sided peripheral portion (17) of the rotor body (11) on which in particular n permanent magnets (16) are fastened.

10. The rotor (10) according to any of the preceding claims, characterized in that the rotor body (11) together with the end wall (26) and the rotor shaft (12) are made of sintered metal.

11. Electrical machine (100) with a rotor (10) according to any of the previous claims, which is rotatably arranged inside a stator (60) with electrical windings (72).

12. The electrical machine (100) according to claim 11, characterized in that the stator (60) has a stator housing (61) with a preferably closed bottom surface (62), at which an axial extension (64) is formed, which extends axially into the cavity (20), and which extension (64) accommodates a first rotor bearing (21) for the rotor shaft (12).

13. The electrical machine (100) according to claim 11 or 12, characterised in that the base surface (62) is produced as a deep-drawn part in one piece with the stator housing (61), and the receptacle (65) for the first rotor bearing (21) is designed as a bent double-layer sheet metal ring (67) at the axial extension (64), wherein the bent double-layer sheet metal ring (67) is arranged axially within the cavity (20).

14. The electrical machine (100) according to one of claims 11 to 13, characterized in that a bearing end cap and/or a connecting plate (74) for an electrical winding (72) is arranged at the stator (60) and the sensor (66) is fastened at the bearing end cap and/or at the connecting plate (74) axially opposite the signal element (28), wherein the sensor (66) is in particular configured as an inductive sensor which is able to detect an axial level difference between an axial standard level (30) of the signal element (28) and the end wall (26).

15. Method for manufacturing a rotor (10) of an electrical machine (100), preferably according to any of claims 11 to 14, characterized in that the rotor (10) with the rotor body (11) and the rotor shaft (12) is manufactured in a single sintering mold, wherein magnetically conductive sintered metal is used as material.