Engaging tool for pressing a disc against a shaft and a rotor shaft for an electric machine

Abstract

An engagement tool (10) for pressing a disk (12) against a shaft (14) is provided, having a pressing table (22) for receiving a first end (18) of the shaft (14), a centering receptacle (26) for receiving a second end (24) of the shaft (14) facing away from the first end (18), a pressing plate (34) for axially pressing the disk (12) onto the shaft (14), and a flexible punch (40) provided on a side of the pressing plate (34) facing the disk (12), for compensating for axial run-out of the disk (12) relative to the pressing plate (34). By means of the flexible punch (40) of the engagement tool (10), a disk (12) having axial run-out can be correspondingly tilted pressed onto the shaft (14), so that a composite rotor shaft (16) of good quality can be achieved.

Description

Technical Field

[0001] The present invention relates to a joining tool for pressing a disc and a shaft together, and a rotor shaft for an electric machine that can be manufactured by means of the joining tool, which can achieve good bonding of the rotor shaft. Background Technology

[0002] As known from DE 10 2010 039 008 A1, a lamination assembly is pushed onto a rotor shaft with radially projecting structural elements in the axial direction, the inner edge of which is plastically deformed by the structural elements of the rotor shaft, thereby producing a form fit in the circumferential direction.

[0003] There is always a need for rotor shafts with good composite properties. Summary of the Invention

[0004] The purpose of this invention is to propose measures that can achieve a rotor shaft with good composite properties.

[0005] According to the present invention, this objective is achieved by a coupling tool having the features described below and a rotor shaft having the features described below. Preferred embodiments and descriptions below provide preferred designs of the invention, which may constitute an aspect of the invention either individually or in combination.

[0006] One aspect of the invention relates to a joining tool for pressing a disc against a shaft, the joining tool comprising: a clamping table for receiving a first end of the shaft, particularly in a rotationally inert manner; a centering receiving portion for receiving a second end of the shaft opposite to the first end; a clamping plate for axially pressing the disc onto the shaft; and a flexible punch disposed on the side of the clamping plate facing the disc, the punch being used to compensate for axial runout of the disc relative to the clamping plate.

[0007] The shaft can be received at its respective end in a clamping table and a centering receiving part, thereby fixing the shaft in a defined position under force during the clamping of the disc. For this purpose, the shaft can be circumferentially fixed by a non-circular profile at its first end, for example, to form a mortise and tenon joint, and thus anti-rotationally fixed in the clamping table. In particular, the shaft's axis of rotation or longitudinal axis is oriented substantially parallel to the clamping direction of the clamping plate. The force applied to the disc by the clamping plate along the axial direction of the shaft can be large enough to cause plastic deformation of the disc at its radially inner edge at the structural element (particularly extending in a rib-like manner along the axial direction of the shaft). This allows for a substantially clearance-free engagement between the disc and the shaft with the structural element, particularly forming a press fit in the engagement region due to the plastic deformation of the disc. Therefore, the strength of the shaft and / or structural element can be higher than the strength of the disc. The discs are specifically designed as stacks of multiple laminations, each lamination having permanent magnets offset from each other in the circumferential direction, thereby enabling the formation of a rotor shaft for an electric machine. Multiple discs can be successively pressed onto the shaft in the axial direction using a joining tool.

[0008] However, the disc clamped to the shaft has intentionally designed or intended axial runout, meaning that the designated axis of rotation of the shaft or disc does not extend perpendicularly to one or both axial end sides of the disc. In a disc with axial runout, the end plane defined by the corresponding end side of the disc extends at an angle relative to a radial plane extending perpendicularly to the axis of rotation. If the clamping plate may act directly on the end side of the disc facing the clamping plate, then the end side of the disc may be planarly aligned with the clamping plate, thereby eliminating the axial runout of the disc and causing the inner radial edge of the disc to extend at an angle relative to the shaft. This may affect the coupling of the disc and the shaft.

[0009] By means of a flexible punch positioned axially between the clamping plate and the disc during the clamping of the disc onto the shaft, the punch can be slightly compressed between the clamping plate and the disc, wherein the punch can be compressed to varying degrees in the circumferential direction. Within the circumferential angle range of the disc, which is positioned closer to the clamping plate due to its axial runout, the punch can be compressed to a greater extent; and within the circumferential angle range of the disc, which is positioned further away from the clamping plate due to its axial runout, the punch can be compressed to a lesser extent. Thus, the punch can fill (e.g., a generally wedge-shaped) intermediate region between the clamping plate, which is oriented perpendicular to the axis of rotation of the shaft, and the end side of the disc, which is oriented obliquely relative to the radial plane of the shaft, and thereby compensate for the axial runout of the disc. Thus, a uniform mechanical stress in the circumferential direction can be applied to the disc by the clamping plate, while simultaneously maintaining the obliqueness of the disc relative to the radial plane of the shaft caused by axial runout and the correct orientation of the inner radial edge of the disc. Therefore, the radial inner edge of the disc is oriented substantially coaxially with the axis of rotation of the shaft, thus ensuring a good fit between the disc and the shaft, which have axial runout. Using the flexible punch of the engagement tool, the disc with axial runout can be pressed onto the shaft at a corresponding angle, thereby achieving a well-fitting rotor shaft.

[0010] The clamping plate can be linearly movable and connected to the clamping table. The clamping plate can be guided by, for example, four guide posts. In particular, at least one spring element, such as a compression spring inserted into the guide posts, is provided between the clamping plate and the clamping table to automatically push the clamping plate away from the disc when the clamping force is substantially no longer applied under no-load conditions. The clamping force required to clamp the disc onto the shaft can be applied to the clamping plate, for example, by means of an external press and / or an intermediate reinforcing mechanism (e.g., a lever). In particular, it is proposed that the shaft be automatically inserted into the clamping table at its first end by means of a robot. For this purpose, the clamping table particularly has an introduction ramp. Preferably, a centering receiver is automatically inserted into the second end of the shaft. For this purpose, the centering receiver particularly has an introduction ramp. The force change curve of the centering receiver when inserted into the second shaft end can be monitored to ensure that the centering receiver actually captures the second end of the shaft protruding from the clamping table and that there is no malfunction. In addition, a suitable sensing device can be installed in the receiving part of the clamping table. This sensing device can detect that the end of the first shaft is inserted into the receiving part of the clamping table and, in particular, that the shaft is correctly oriented before allowing the disc to be clamped onto the shaft by the engagement tool.

[0011] For example, the disc can be guided with clearance to the (especially tapered) region at the end of the second shaft, and then the shaft is subsequently tightened to the larger diameter of the shaft and / or the axial region with structural elements, especially at both ends, to prevent movement. To form a longitudinal press fit, a press fit can be provided between the disc and the shaft during pressing. To form a transverse press fit, a clearance fit can be provided between the disc and the shaft during pressing, which can be achieved by heating the disc and / or cooling the shaft, while in an unconditioned state, a press fit is provided when both the disc and the shaft have the same temperature. The desired temperature of the disc and / or the shaft can be monitored using a temperature sensor.

[0012] To avoid unnecessary mechanical resistance during clamping, the shaft can be lubricated with a lubricant, such as lubricating oil. Preferably, a lubrication device that moves with the clamping plate is provided, which applies a lubricant film to the shaft during the return motion of the clamping plate after the disc is clamped onto it. Particularly preferably, a chip detection sensor, preferably optically operated, is provided, which also moves with the clamping plate. If the chip detection sensor detects chips that have fallen from the shaft and / or disc, this indicates significant damage and operational failure, which in particular leads to a direct interruption of the clamping process.

[0013] In particular, the punch has segmented contact surfaces for contacting the disc, especially radially spaced annular contact surfaces, wherein gaps are formed between the segmented contact surfaces to receive the elastically deformable material of the punch. The punch may, for example, have a wavy cross-sectional profile in the radial direction on a cross-section of a radial plane extending perpendicular to the axis of rotation of the shaft, formed, for example, by concentric, annular contact surfaces spaced apart in the radial direction. Thus, segments that make contact with the disc and other segments that do not make contact are created on the side of the punch facing the disc. Sufficient force can be transmitted between the pressure plate and the disc by the punch through multiple segmented contact surfaces, while simultaneously forming sufficiently large gaps at the edges of the contact surfaces, into which the elastically deformable material of the punch can be offset under load. The punch is particularly made of elastomeric materials and / or rubber-elastic materials, such as hard rubber. The punch can act directly on the disc. However, an intermediate ring (e.g., made of copper alloy or steel) can also be provided between the punch and the disc, allowing the disc to abut against the intermediate ring over a large area. This prevents the upper lamellae of the disc, which is made of stacked lamellae, from detaching. The intermediate ring, in particular, can have clearance relative to the shaft, thus preventing the intermediate ring from contacting the shaft and / or damaging it.

[0014] Preferably, the punch is made of an elastomeric material and / or a rubber-elastic material, wherein the punch can be compressed by 0.1 mm ≤ Δε ≤ 10.0 mm, particularly 0.5 mm ≤ Δε ≤ 5.0 mm, and preferably Δε = 2.0 mm ± 0.2 mm, when the clamping force F is 10 kN ≤ F ≤ 100 kN. For the disc, there is, for example, an axial runout of about 0.2 mm to 1.0 mm between the farthest and nearest protrusions on the end side inclined relative to the radial plane of the shaft in the axial direction, thus the correspondingly small elastic deformation of the punch is sufficient under the expected clamping force. Therefore, the punch can be made relatively stiff and correspondingly can transmit a large force without significant plastic deformation.

[0015] Particularly preferably, the punch is designed to be annular and radially spaced from the shaft, wherein the punch is specifically positioned only in the radially outer radial region of the disk. For example, the annular punch is positioned in the outer half of the radius of the radial region between the radially inner and radially outer radii of the disk. This allows force to be applied to the disk as much as possible along its outer circumference, thereby achieving a substantially constant stress distribution within the disk despite the end sides being inclined relative to the radial plane of the shaft.

[0016] In particular, the centering receiving part is guided axially within the clamping plate. This prevents the centering receiving part from tilting, thus keeping the shaft stationary and correctly oriented during the movement of the clamping plate. Here, the centering receiving part can be supported on the clamping plate in the radial direction. For example, a sliding bearing can be designed between the clamping plate and the centering receiving part.

[0017] Preferably, a guide element is provided in the cavity of the disc for positioning the disc circumferentially relative to the axis, wherein the guide element is connected to a clamping plate. This prevents the disc from twisting circumferentially relative to the axis during clamping. In particular, the guide element can be displaced in a defined increment in the circumferential direction, thereby allowing the individual discs to be clamped with a defined offset in the circumferential direction. This makes it possible to implement the discs as identical components having permanent magnets offset from each other in the circumferential direction on their outer circumference, thereby allowing the permanent magnets of different discs to be positioned slightly offset from each other in the circumferential direction. This improves the smoothness of the rotor shaft operation of the electric machine.

[0018] Particularly preferably, a force gauge is provided for measuring the reaction force acting on the clamping plate, wherein the force gauge is connected to a control device to terminate the clamping of the disc onto the shaft in the event of a sudden increase in the reaction force and / or an unreasonable force-displacement curve. Thus, the clamping plate can move the disc along the axial direction of the shaft until the disc comes to a stop with a stop or other body, especially a previously clamped disc. This stop causes a sudden increase in resistance detectable by the force gauge. This prevents damage to both the newly clamped disc and the previously clamped disc. Furthermore, a cooling gap can be formed between the orientations of the planes facing each other (each having axial runout but torsional relative to each other in the circumferential direction). Plastic deformation of the disc filling the gap can be prevented. In addition, the force gauge can measure the force-displacement curve over time and compare it with the expected force-displacement curve and / or the expected basic form of the force-displacement curve to identify undesirable faults. For example, pulsed force-displacement curves and / or measurements that are significantly too high for the applied force may indicate a fault, and thus the structural unit consisting of the shaft and the clamped disc can be automatically sorted out as a defective part that does not meet the quality requirements.

[0019] Another aspect of the invention relates to a rotor shaft for an electric motor, which can be manufactured, in particular, using joining tools and / or methods that can be designed and improved as described above. The rotor shaft comprises: a shaft having a guide region for guiding discs with radial clearance and a fastening region for fastening the discs, having a radially projecting structural element axially offset relative to the guide region; and a plurality of discs, each having axial runout, wherein the discs are form-fitted in the circumferential direction in the fastening region due to plastic deformation at the structural element, and force-fitted to the shaft in the radial direction by transverse and / or longitudinal compression. The rotor shaft can be designed and improved, in particular, as described above regarding manufacturing using joining tools. With the flexible punch of the joining tool, the axially runout discs can be correspondingly tilted and pressed onto the shaft, thereby enabling a well-fitting rotor shaft.

[0020] In particular, a gap is formed due to the axial runout of the disks that are successive to each other in the axial direction. The planes of the disks facing each other can be positioned to be twisted relative to each other in the circumferential direction about their parallel relative positions, especially twisted by approximately 180°. As a result, a gap, for example generally wedge-shaped, is created between the axially successive end faces of the disks, which allows for better cooling of the disks when used as rotors with permanent magnets in electric motors during continuous operation.

[0021] Preferably, the structural elements extending in a rib-like manner, particularly in the axial direction of the shaft, generally include a tapered surface that gradually narrows toward the threading area on their radially outward-pointing outer surface. This prevents the indentation caused by plastic deformation at the radially inner edge of the disc from widening and loosening further as the structural element moves. It also prevents weakening of the disc-shaft bond and achieves equally good bonding in any axial segment of the fastening area for each disc. Attached Figure Description

[0022] The invention is illustrated below by way of example with reference to the accompanying drawings, and the features shown below, whether individually or in combination, can form an aspect of the invention. In the drawings:

[0023] Figure 1 A schematic cross-sectional view of the joining tool is shown, and

[0024] Figure 2 : Shows that it is possible to use Figure 1 A schematic perspective view of a rotor shaft manufactured using a joining tool. Detailed Implementation

[0025] exist Figure 1 The joining tool 10 shown can clamp the disc 12 with axial runout and the shaft 14 respectively, thereby manufacturing the rotor shaft 16 for an electric motor machine used in an electrically driven motor vehicle. For this purpose, the shaft 14 can first be inserted into the receiving portion 20 of the clamping table 22 at its first end 18 and then into the centering receiving portion 26 at its opposite second end 24. The shaft 14 can thus be positioned in a fixed position. The disc 12 can be inserted into the through-feed area 28 of the shaft 14 with clearance. A fastening area 30 can be connected at the through-feed area 28, in which a plurality of radially outwardly projecting, axially extending, rib-like structural elements 32 are provided. By means of a clamping plate 34, in particular hydraulically actuated, the disc 12 can be pressed into the fastening area 30 in the axial direction of the shaft 14, wherein the structural elements 32 are embedded in the material of the disc 12 at its radially inner edge, thereby creating a circumferentially form-fitting, interlocking composite. Here, the clamping plate 34 can move linearly parallel to the designated axis of rotation of the shaft 14 on the guide post 36 connected to the clamping table 22.

[0026] Because the disc 12 has an intentional or deliberate axial runout, the end face 38 of the disc 12 may extend obliquely relative to the radial plane of the shaft 14, which extends perpendicularly to the axis of rotation of the shaft 14. To prevent loss of proper alignment between the radially inner edge of the disc 12 and the shaft 14 during clamping, an annular punch 40 made of a slightly flexible material is provided between the clamping plate 34 and the disc 12. This punch acts on the disc 12 as far as possible on its outer periphery, particularly through an intermediate ring disposed between them. The punch 12 may have segmented contact surfaces 44 on its sides pointing towards the disc 12 and the clamping table 22. These contact surfaces are formed, for example, by concentric and spaced-apart rings that, in the illustrated cross-sectional view, form a radially wavy pattern on the sides of the punch 40. Thus, the punch 40 can be easily compressed more strongly in one circumferential angle range and less strongly in another, so as to compensate for the axial runout of the disc 12 during clamping.

[0027] As in Figure 2 As shown, a disk 12 (especially made of a stack of plates) having a plurality of permanent magnets 42 can be pressed against a shaft 14 by means of a joining tool 10. Here, the disk 12 can be pressed against each other in a circumferentially twisted manner, such that the permanent magnets 42 that are successively arranged in the axial direction are slightly offset from each other in the circumferential direction and are not precisely aligned with each other.

Claims

1. A coupling tool for pressing a disc (12) against a shaft (14), the coupling tool having: A clamping table (22) is used to receive the first end (18) of the shaft (14); A center receiving part (26) is used to receive the second end (24) of the shaft (14) that is away from the first end (18). A clamping plate (34) is used to axially press the disc (12) onto the shaft (14); and A flexible punch (40) is disposed on the side of the clamping plate (34) facing the disc (12), the punch being used to compensate for axial runout of the disc (12) relative to the clamping plate (34), the punch (40) having segmented contact surfaces (44) for contacting the disc (12), wherein gaps are formed between the segmented contact surfaces (44) for receiving elastically deformable material of the punch (40).

2. The joining tool according to claim 1, characterized in that, The clamping table (22) is used to receive the first end (18) of the shaft (14) in a non-rotational manner.

3. The joining tool according to claim 1, characterized in that, The segmented contact surfaces (44) are radially spaced-apart annular contact surfaces.

4. The joining tool according to claim 1, characterized in that, The punch (40) is made of an elastomeric material and / or a rubber elastic material.

5. The joining tool according to claim 4, characterized in that, The punch (40) can be compressed by 0.1 mm ≤ Δε ≤ 10.0 mm when the clamping force F is 10 kN ≤ F ≤ 100 kN.

6. The joining tool according to claim 4, characterized in that, The punch (40) can be compressed by 0.5 mm ≤ Δε ≤ 5.0 mm when the clamping force F is 10 kN ≤ F ≤ 100 kN.

7. The joining tool according to claim 4, characterized in that, The punch (40) can be compressed by Δε = 2.0 mm ± 0.2 mm when the clamping force F is 10 kN ≤ F ≤ 100 kN.

8. The joining tool according to any one of claims 1 to 7, characterized in that, The punch (40) is designed to be annular and radially spaced from the axis.

9. The joining tool according to claim 8, characterized in that, The punch (40) is only located in the radially outer region of the disc (12).

10. The joining tool according to any one of claims 1 to 7, characterized in that, The centering receiving part (26) is axially movable within the clamping plate (34).

11. The joining tool according to any one of claims 1 to 7, characterized in that, A guide element is provided in the cavity of the disk (12) for engaging, the guide element being used to position the disk (12) relative to the axis (14) in the circumferential direction.

12. The joining tool according to claim 11, characterized in that, The guiding element is connected to the clamping plate (34).

13. The joining tool according to any one of claims 1 to 7, characterized in that, A force gauge is provided for measuring the reaction force acting on the clamping plate (34), wherein the force gauge is connected to a control device to stop the disc (12) from pressing onto the shaft (14) in case the reaction force increases abruptly and / or in case the force-displacement curve is unreasonable.

14. A rotor shaft for an electric motor, the rotor shaft being manufactureable using a joining tool (10) according to any one of claims 1 to 13, the rotor shaft having: A shaft (14), wherein the shaft (14) has a threading region (28) for threading a disk (12) with radial clearance and a fastening region (30) for fastening the disk (12) to a structural element (32) that is axially offset relative to the threading region (28); and Each has a plurality of discs (12) that have axial runout, wherein the discs (12) are form-fitted in the circumferential direction due to plastic deformation at the structural element (32) in the fastening region and are force-fitted to the shaft (14) in the radial direction by transverse compression and / or longitudinal compression.

15. The rotor shaft according to claim 14, characterized in that, The gap is formed by the axial movement of the disks (12) that are successive to each other in the axial direction.

16. The rotor shaft according to claim 14 or 15, characterized in that, The structural element (32) includes a tapered surface that gradually narrows toward the threading region (28) on its radially outward-pointing outer surface.

17. The rotor shaft according to claim 16, characterized in that, The structural element (32) extends in a rib-like manner in the axial direction of the shaft.

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