Rotor for an electric motor, method for mounting a laminate pack on a rotor shaft and mounting device

Abstract

A rotor for an electric motor has a rotor shaft whose end section forms a clamping section and is shaped like a mushroom head. The invention also includes a method and an assembly device for manufacturing the rotor.

Description

[0001] The invention relates to a rotor for an electric motor, comprising a rotor shaft and a disk pack arranged on the shaft. The invention also relates to a method for mounting a disk pack on a rotor shaft. Finally, the invention relates to an assembly device for mounting a disk pack on a rotor shaft. State of the art

[0002] DE 10 2008 004 876 A1 describes an electric machine whose rotor comprises a rotor shaft and a plate pack mounted on the rotor shaft, consisting of a plurality of individual plates. Each plate has a central recess through which the plate is pushed onto the rotor shaft. The central recess of the plate has a non-circular cross-sectional shape and features spring tongues in the circumferential direction, which are deflected in the axial direction during assembly.

[0003] Furthermore, it is known to attach plate packs or layered individual plates to a rotor shaft with multiple longitudinal grooves along its circumference by axial compression during assembly to ensure that the required torque can be transmitted during operation. The support of the press-on forces during assembly is usually provided at the opposite, exposed end of the rotor shaft. Disclosure of the invention

[0004] In the following, the term "axial" refers to the longitudinal axis of the rotor and rotor shaft. Accordingly, the terms "radial," "transverse," and "lateral" refer to the direction perpendicular to the longitudinal axis of the rotor and rotor shaft.

[0005] The rotor according to the invention can be used in electrical machines or electric motors, which are particularly designed as permanent-magnet machines with permanent magnets on the rotor side. The rotor has a rotor shaft and a lamination pack on the rotor shaft, which consists of a plurality of individual laminations arranged parallel to one another, with the plane of the laminations extending perpendicular to the longitudinal axis of the rotor shaft. Each lamination has a central recess through which the lamination is pushed onto the rotor shaft.

[0006] One end section of the rotor shaft forms a clamping section and is shaped like a mushroom head, featuring a radial undercut spaced apart from the end face of the rotor shaft. This design enables the axially secure connection of the rotor shaft to a tie rod, which is part of an assembly device, during assembly of the disk pack. The disk pack can then be attached without exerting force on the ball bearings and any existing housing part in which the rotor shaft is rotatably mounted. Furthermore, the rotor shaft itself is relieved of axial compressive forces during the assembly process, as no end support is required at the opposite end of the rotor shaft, and no compressive forces need to be absorbed.The rotor shaft end in the mushroom head design is connected to the tie rod of the mounting device, whereby during the sliding of the disk pack onto the rotor shaft only tensile forces act on the rotor shaft, which are transmitted via the tie rod to a hold-down device of the mounting device.

[0007] In an advantageous embodiment, the clamping section of the rotor shaft protrudes from the plate pack after assembly is complete. This has the advantage that, once the plate pack has been mounted on the rotor shaft, the tie rod can be easily removed from the rotor shaft. For example, it is possible to move the tie rod—relative to the longitudinal axis of the rotor shaft—laterally or radially toward the rotor shaft to connect it to the rotor shaft, creating a positive connection, and then move it laterally or radially away from the rotor shaft upon release. This can be done without interference from the plate pack due to the protruding clamping section of the rotor shaft.

[0008] The invention also relates to an electric motor or an electric machine provided with a rotor as described above and a stator. The electric motor or electric machine is designed in particular as a permanently excited, electronically commutated motor.

[0009] A further aspect of the invention relates to a method for mounting a disk pack on a rotor shaft of a rotor, in particular of a rotor as described above. The mounting method is carried out with the aid of a mounting device which comprises a hold-down device and a tie rod whose diameter is smaller than the inner diameter of the central recess in the disk pack, with which the disk pack is pushed onto the rotor shaft. In the method, in a first step, the disk pack without the rotor shaft is pushed onto the tie rod of the mounting device until it stops on the hold-down device. Subsequently, in a second step, the tie rod of the mounting device is coupled to the rotor shaft. Then, in a third step, the tie rod pulls the rotor shaft through the disk pack to create a press connection.

[0010] This procedure enables a force-reduced assembly of the disk pack onto the rotor shaft. In particular, compressive forces along the longitudinal axis of the rotor shaft are eliminated, eliminating the need to support the rotor shaft at the end opposite the tie rod. The rotor shaft can be assembled with a pre-assembled housing section in which the opposite end of the rotor shaft is mounted. Ball bearings supporting the rotor shaft are relieved of assembly forces. The forces occurring during assembly act as tensile forces on the rotor shaft and are supported by the tie rod and the hold-down device of the assembly device.

[0011] According to an advantageous embodiment, the coupling of the tie rod to the rotor shaft is established by a positive connection between the tie rod and the rotor shaft. It is advantageous for the end sections of the rotor shaft and tie rod to each be provided with a clamping section, which are moved radially into each other to create an axially positive connection. The clamping section on the end face of the rotor shaft is designed, in particular, in the manner of a mushroom head and provided with a radial undercut, which enables an axially positive connection with the tie rod.

[0012] According to a further advantageous embodiment, the rotor shaft is rotatably mounted in a housing part, which is adjusted together with the rotor shaft by the tie rod during assembly. The method is therefore particularly suitable for pre-assembled units consisting of a rotor shaft and a housing part, with the end of the rotor shaft facing away from the clamping section located in the housing part. During assembly of the disk pack and rotor shaft, the assembly comprising the rotor shaft and housing part is pulled by the tie rod toward the hold-down device in the manner described above, so that the disk pack resting on the hold-down device is pushed onto the rotor shaft.

[0013] According to yet another advantageous embodiment, permanent magnets arranged on the disk pack magnetically secure the disk pack to the hold-down device. This has the advantage that additional fastening measures for holding the disk pack to the hold-down device are dispensed with.

[0014] According to a further advantageous embodiment, the tie rod pulls the rotor shaft through the disk pack until the end section of the rotor shaft protrudes beyond the disk pack and into a recess in the hold-down device. This ensures that the free end face of the rotor shaft protrudes from the disk pack in the fully assembled state and can, if necessary, be mounted in a bearing of a unit accommodating the electric motor during installation of the electric motor, into which the rotor shaft is integrated.

[0015] According to yet another advantageous embodiment, after the press connection has been established and the axial end position between the rotor shaft and the disk pack has been reached, the tie rod is retracted from the hold-down device, whereupon the connection between the tie rod and the rotor shaft is released.

[0016] Yet another aspect of the invention relates to an assembly device for mounting a disk pack on a rotor shaft of a rotor, in particular a rotor as described above, for carrying out the above-described method. Accordingly, the assembly device allows the assembly of a disk pack on a rotor shaft to be carried out in a simple manner in several consecutive steps.

[0017] The assembly device comprises a hold-down device and a tie rod which is adjustably guided in the hold-down device and is designed for a positive connection to a rotor shaft whose end section forms a clamping section. The end section of the tie rod also forms a clamping section. This is designed as a hollow body, in the wall of which two axially superimposed insertion openings are made, which are designed to receive the corresponding clamping section of the rotor shaft. The insertion openings on one side of the tie rod have different extensions in the circumferential direction: the insertion opening closer to the end face of the tie rod has a smaller extension in the circumferential direction than the insertion opening further away from the end face. This design enables a mushroom-head clamping section of the rotor shaft to be inserted laterally into the insertion openings of the tie rod.The radially wider section of the mushroom head on the front side of the rotor shaft lies in the larger insertion opening, whereas the radially reduced section of the mushroom head, which is spaced apart from the front side of the rotor shaft, is enclosed by the walls of the smaller insertion opening in the tie rod, with the radially wider section of the mushroom head resting against these walls. Once the mushroom head clamping section is inserted, a positive connection is created in the axial direction, through which axial tensile and compressive forces can be transmitted between the tie rod and the rotor shaft.

[0018] Further advantages and practical embodiments can be found in the further claims, the description of the figures, and the drawings. They show: Fig. 1 a section through an electric motor with a rotor and a housing part in which a rotor shaft of the rotor is rotatably mounted, wherein a plate pack with permanent magnets is seated on the rotor shaft, Fig. 2 a perspective view of the rotor of the electric motor, Fig. 3 a mounting device for mounting the disk pack on the rotor shaft, with a hold-down device and a tension rod adjustable in the hold-down device, Fig. 4 the tie rod in an enlarged view, Fig. 5 a first assembly step with the plate pack pushed onto the tie rod of the assembly device, Fig. 6 an intermediate step in the assembly with the rotor without the disk pack approaching the assembly device, Fig. 7 the free end section of the rotor shaft in an enlarged individual view, Fig. 8 a further assembly step with a positive connection between the tie rod of the assembly device and the rotor shaft, Fig. 9 in an enlarged view the positive connection of tie rod and rotor shaft, Fig. 10 In a next assembly step, the rotor shaft is pulled by the tie rod through the plate pack attached to the hold-down device.

[0019] In the figures, identical components are provided with identical reference symbols.

[0020] In the Fig. 1 and Fig. Figure 2 shows a rotor 1 of an electric motor. The rotor 1 forms a preassembled unit with a housing part 2, which is part of the electric motor. The rotor shaft 4 of the rotor 1 is rotatably mounted in the housing part 2 in a ball bearing 3 of the housing part 2. A lamination pack 5 is non-rotatably mounted on the rotor shaft 4. This lamination pack is constructed from a plurality of individual, parallel-layered laminations and supports permanent magnets 6 distributed around the circumference. The rotor 1, together with a stator, forms a permanently excited electric motor.

[0021] The following Fig. 3 to 10 illustrate various assembly steps in the assembly of rotor shaft 4 and disk pack 5. Here, the assembly unit with the rotor 1, but still without the disk pack, and the housing part 2 is brought to an assembly device 7, with the aid of which the disk pack 5 is pressed onto the rotor shaft 4 in a material-saving manner and brought into a rotationally fixed connection.

[0022] In Fig. 3, the mounting device 7 is shown in detail. The mounting device 7 comprises a hold-down device 8 made of soft magnetic material and a tie rod 9, which is adjustably guided in a recess in the hold-down device 8. The tie rod 9 has a free end section 9a protruding from the hold-down device 8, which is designed as a clamping section and serves to provide a positive connection with the rotor shaft 4 ( Fig. 8, Fig. 9). The tie rod 9 is designed as a hollow shaft and thus forms an axially continuous hollow body. In the area of ​​the front clamping section 9a, two axially superimposed insertion openings 9b, 9c are introduced into the wall of the tie rod 9 ( Fig. 4), which serves to positively receive the mushroom-shaped end section 4a of the rotor shaft 4, which also forms a clamping section. The insertion opening 9b, which directly adjoins the end face of the tie rod 9, has a smaller extent in the circumferential direction than the insertion opening 9c located directly above it. The insertion opening extends, for example, over an angular segment of a maximum of 90°, whereas the insertion opening 9c located above it extends, for example, over an angular segment that is greater than 90° and preferably less than 120°.

[0023] The mushroom-shaped clamping section 4a of the rotor shaft 4 has a head 4b located directly on the front side, which is separated from the other rotor shaft 4 by a section 4c, but is formed integrally with the rotor shaft 4. The diameter of the head 4b is slightly smaller than the diameter of the rotor shaft 4. In the assembled state of the rotor shaft 4 and the tie rod 9 ( Fig. 8 to 10), the head 4b of the rotor shaft 4 projects into the insertion opening 9c of the clamping section of the tie rod 9 and is positively engaged behind by the bounding walls of the further insertion opening 9b in the region of an undercut 4c formed as a notch, which adjoins the head 4b. In this way, a positive tension-compression connection is created in the axial direction between the rotor shaft 4 and the tie rod 9. The rotor shaft 4 and the tie rod 9 are joined by laterally inserting the clamping sections into one another. Conversely, the positive connection is released by laterally moving the clamping sections apart from one another in the opposite direction.

[0024] The process of assembling the disk pack 5 on the rotor shaft 4 is carried out in the following steps: First, in a first step, as in Fig. As shown in Figure 5, the plate pack 5 is pushed axially, as indicated by the arrows, onto the tie rod 9 until the end face of the plate pack 5 makes contact with the hold-down device of the assembly device 7. The diameter of the tie rod 9 is advantageously smaller than the diameter of the central recess in the plate pack 5, so that pushing it on can be performed with little force. The permanent magnets 6 on the plate pack 5 hold it to the hold-down device 8 with magnetic force.

[0025] In a next step, the rotor 1 including the housing part 2 without the disk pack is brought closer to the assembly device 7 ( Fig. 6, Fig. 8) and the positive connection between the clamping sections 4a of the rotor shaft 4 and 9a of the tie rod 9 is produced by lateral insertion.

[0026] In the following process step ( Fig.10), the tie rod is pulled axially into the hold-down device 8, whereby the rotor shaft 4, which has an oversize compared to the central recess in the plate pack 5, is pulled with a press fit through the plate pack 5 until the axial end position of the plate pack 5 on the rotor shaft 4 is reached. The tie rod 9 can then be moved axially out of the hold-down device 8 again, whereby the rotor 1 including the plate pack 5 is removed from the hold-down device 8. The positive connection between the clamping sections 4a and 9a on the rotor shaft 4 or the tie rod 9 can be released by sliding them apart sideways. The process of mounting the plate pack 5 on the rotor shaft 4 is now complete. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 004 876 A1

[0002]

Claims

[1] Rotor for an electric motor, with a rotor shaft (4) and a disk pack (5) arranged on the rotor shaft (4), which has a central recess for the rotor shaft (4) and is pushed onto the rotor shaft (4), characterized by that an end section of the rotor shaft (4) forms a clamping section (4a) and is designed in the manner of a mushroom head which is provided with a radial undercut (4c) which is arranged at a distance from the end face of the rotor shaft (4). [2] Rotor according to claim 1, characterized by that the clamping section (4a) of the rotor shaft (4) projects axially from the disk pack (5) - and in particular the clamping section (4a) has a smaller outer diameter in the manner of a mushroom head than the rotor shaft (4) in the axial region of the disk pack (5). [3] Electric motor, with a rotor (1) according to one of claims 1 or 2 and with a stator - wherein preferably the stator has electrical windings which interact with permanent magnets (6) which are fastened to the rotor. [4] Method for mounting a disk pack (5) on a rotor shaft (4) of a rotor (1), in particular a rotor (1) according to one of claims 1 to 2, using a mounting device (7) comprising a hold-down device (8) and a tie rod (9) whose diameter is smaller than the inner diameter of the central recess in the disk pack (5), with the following method steps: - first, the plate pack (5) without the rotor shaft (4) is pushed onto the tie rod (9) of the assembly device (7) until it reaches a stop on the hold-down device (8), - then the tie rod (9) of the mounting device (7) is coupled to the rotor shaft (4), - then the tie rod (9) pulls the rotor shaft (4) axially through the plate pack (5) to create a press connection. [5] Method according to claim 4, characterized by that the coupling of the tie rod (9) with the rotor shaft (4) is established by positively connecting the tie rod (9) and the rotor shaft (4). [6] Method according to claim 5, characterized by that the end sections of the rotor shaft (4) and tie rod (9) are each provided with a clamping section (4a, 9a) which are moved into one another in the radial direction to produce an axially positive connection. [7] Method according to one of claims 4 to 6, characterized by that the rotor shaft (4) is rotatably received in a housing part (2) of the electric motor, which is moved together with the rotor shaft (4) by the tie rod (9) in the axial direction. [8] Method according to one of claims 4 to 7, characterized by, that the permanent magnets (6) arranged on the disk pack (5) magnetically secure the disk pack (5) to the hold-down device (8). [9] Method according to one of claims 4 to 8, characterized by that the tie rod (9) pulls the rotor shaft (4) through the plate pack (5) until the end section (4a) of the rotor shaft (4) projects beyond the plate pack (5) and projects into a recess in the hold-down device (8). [10] Method according to one of claims 4 to 9, characterized by that after the press connection and the axial end position between the rotor shaft (4) and the disk pack (5) have been established, the tie rod (9) is axially retracted from the hold-down device (8) and the connection between the tie rod (9) and the rotor shaft (4) is then released. [11] Mounting device for mounting a disk pack (5) on a rotor shaft (4) of a rotor (1), in particular a rotor (1) according to one of claims 1 to 2, for carrying out the method according to one of claims 4 to 10, comprising a hold-down device (8) and a tie rod (9) which is guided axially adjustably in the hold-down device (8), the end section of which is designed as a clamping section (9a), wherein the clamping section (9a) is designed as a hollow body, in the wall of which two insertion openings (9b, 9c) are made axially one above the other, wherein the insertion opening (9b) which is closer to the end face of the tie rod (9) has a smaller extension in the circumferential direction than the insertion opening (9c) which is further away from the end face.

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