Sensor assembly for a rotor of an electric machine, electric machine and method for manufacturing a sensor assembly

Abstract

Sensor assembly (1) for a rotor of an electric machine, electric machine and method for producing a sensor assembly (1), wherein the sensor assembly (1) has a magnet (5), a cover part (2) and a sleeve (3), wherein the sleeve (3) is connected with the rotor and the cover part (2) is connected with the sleeve (3), wherein the magnet (5) is held in the cover part (2) by a shrink connection, in particular a laser shrink connection.

Description

Technical Field

[0001] The present invention relates to a sensor assembly for a rotor of an electric motor, an electric motor, and a method for manufacturing such a sensor assembly. Background Technology

[0002] Document DE 10 2021 205 297 A1 discloses a rotor for an electric motor, an electric motor, and a method for manufacturing such a rotor.

[0003] Document DE 10 2011 112 822 A1 illustrates an electric motor in a drive assembly of a motor vehicle. Summary of the Invention

[0004] The core of this invention for a sensor assembly for an electric motor rotor is that the sensor assembly has a magnet, a cover portion and a sleeve, wherein the sleeve is connected to the rotor and the cover portion is connected to the sleeve, wherein the magnet is held in the cover portion by a shrink connection, especially a laser shrink connection.

[0005] The background of this invention is that a magnet can be securely connected to a sensor assembly. Here, the thermal load or force acting on the magnet can be reduced, allowing the use of a sensitive magnet with a high magnetic field strength for the sensor assembly. In this case, a defined holding force can be advantageously set.

[0006] Advantageously, this sensor assembly is used as a rotor position sensor for a motor. In this case, the installation space can be reduced.

[0007] Shrink connection here refers to a type of extrusion connection, which is achieved by means of shrunken material or by means of a narrowed portion.

[0008] Laser shrink joining refers to a type of extrusion joining achieved by means of laser-welded shrink sections or narrowed portions. In this case, the material is not welded to another workpiece, but rather welded to only 50% to 80% of the material thickness, thus forming a weld seam, which reduces the inner diameter of the cap portion and / or sleeve.

[0009] Further advantageous embodiments of the invention are the subject of the dependent claims.

[0010] According to an advantageous design, the cover portion has a bottom section and a protrusion, wherein the protrusion extends along the circumferential side of the magnet and holds the magnet. Thus, the cover portion at least partially surrounds the magnet, forming a housing.

[0011] Advantageously, the protrusion is arranged radially between the magnet and the sleeve, wherein the sleeve has at least one circumferentially spiraling laser-contracted section, which in particular allows the protrusion to press against the magnet. This achieves a secure connection between the magnet and the cover portion, while minimizing the thermal load or force acting on the magnet.

[0012] Furthermore, the inner diameter of the sleeve has a stepped portion, with the bottom section of the cover portion placed on the stepped portion, thus positioning the bottom section between the stepped portion and the magnet. Consequently, the surface of the magnet facing the magnetic field sensor is not obstructed, allowing the magnet to operate without shielding.

[0013] Alternatively, the sleeve has an advantageous stepped inner diameter, on which the magnet is placed, thus arranging the magnet between the stepped portion and the bottom section of the cover portion. This achieves a robust connection between the magnet and the sensor assembly. Here, the thickness of the bottom section is chosen to minimize shielding of the magnetic field from the magnet to the magnetic field sensor.

[0014] According to another advantageous design, the lid portion is cup-shaped, wherein the magnet is housed within the lid portion. Thus, the lid portion at least partially surrounds the magnet, forming a shell.

[0015] Advantageously, the outer diameter of the sleeve increases in a stepped manner from the magnet to the rotor, wherein the cover portion is arranged on the sleeve and extends from the minimum outer diameter of the sleeve to the maximum outer diameter of the sleeve. This allows the magnet to be pre-assembled between the cover portion and the sleeve.

[0016] Furthermore, it is advantageous that the cover portion has a reduced inner diameter, particularly a narrowing portion, in the region of the sleeve's minimum outer diameter. Specifically, the cover portion has a laser-shrink connection in the region of the reduced inner diameter. The reduced inner diameter allows the cover portion to be pressed onto the sleeve, thereby positioning the magnet on the outer bottom section of the sleeve.

[0017] Advantageously, particularly in the region of the sleeve's maximum outer diameter, the cover portion is connected and / or force-transmitting to the sleeve material. Thus, the magnet can be pre-assembled between the cover portion and the sleeve.

[0018] According to another advantageous design, the sleeve is connected to the rotor for force transmission and / or material connection, specifically, wherein the outer diameter of the rotor is smaller than the outer diameter of the sleeve. This sleeve can be used as a tolerance compensation sleeve between the rotor and the magnet.

[0019] The core of this invention for an electric motor is that the motor has a rotor and a sensor assembly, particularly a sensor assembly as described above or according to any one of the claims concerning the sensor assembly.

[0020] The background of this invention is that the sensor assembly can be designed to be compact, thereby reducing the installation space required in the motor.

[0021] The core of the present invention for the method of manufacturing a sensor assembly having a magnet, a sleeve, and a cover portion, particularly a sensor assembly as described above or according to any one of the claims concerning the sensor assembly, is that a magnet is introduced into the cover portion, wherein the cover portion and / or the sleeve are subsequently contracted by means of a laser, such that the magnet is held by the cover portion.

[0022] The background of this invention is to securely connect a magnet to a sensor assembly. In this case, the thermal load or force acting on the magnet is reduced, allowing the use of a sensitive magnet with a high magnetic field strength for the sensor assembly. A defined holding force can be advantageously set here.

[0023] According to an advantageous design, the cover portion is force-transmittingly connected and / or material-connected to the sleeve before laser shrinkage. This allows the magnet to be pre-assembled between the cover portion and the sleeve.

[0024] Advantageously, the sleeve and rotor are connected in the first step of the process. This reduces the thermal load on the magnet.

[0025] Alternatively, it is advantageous to connect the sleeve and the rotor in the final process step. This allows the sensor assembly to be manufactured as a pre-assembled unit.

[0026] The above-described design schemes and improvements can be combined with each other arbitrarily, as long as it is meaningful. Other feasible design schemes, improvements, and implementations of the present invention include combinations of features of the invention not explicitly mentioned in the preceding or following descriptions of the embodiments. In particular, those skilled in the art will add certain aspects as improvements or supplements to the corresponding basic forms of the present invention. Attached Figure Description

[0027] The invention will be explained in the following sections with reference to embodiments, from which further inventive features can be derived, but the scope of the invention is not limited thereto. These embodiments are illustrated in the accompanying drawings.

[0028] in:

[0029] Figure 1 A cross-sectional view of the sensor assembly 1 of the rotor according to a first embodiment of the present invention is shown;

[0030] Figure 2 A cross-sectional view of a sensor assembly 100 of a rotor according to a second embodiment of the present invention is shown;

[0031] Figure 3A cross-sectional view of a sensor assembly 200 of a rotor according to a third embodiment of the present invention is shown during the first method step 301.

[0032] Figure 4 A cross-sectional view of the sensor assembly 200 of the rotor according to the third embodiment is shown during the second method step 302;

[0033] Figure 5 A cross-sectional view of a rotor sensor assembly 200 according to a third embodiment of the present invention is shown during third method step 303;

[0034] Figure 6 A schematic flowchart of a first variant of a method 300 for manufacturing a sensor assembly (1, 100, 200) for a rotor according to the present invention is shown, and

[0035] Figure 7 A schematic flowchart of a second variant of a method 400 for manufacturing a sensor assembly (1, 100, 200) for a rotor according to the present invention is shown. Detailed Implementation

[0036] Figure 1 The first embodiment of the sensor assembly 1 according to the present invention shown has a magnet 5, a cover portion 2 and a sleeve 3.

[0037] The magnet 5 is preferably designed as a permanent magnet, especially a neodymium magnet. The magnet 5 is designed to be generally disk-shaped and have a circular cross-section. Here, the height of the magnet 5 is smaller than the diameter of the magnet 5.

[0038] Sleeve 3 is arranged between magnet 5 and Figure 1 Between the rotors (not shown). The sleeve 3 is made of stainless steel. The sleeve is a hollow cylinder and has a first inner diameter and a second inner diameter. Here, the first inner diameter is arranged facing the rotor. The second inner diameter is arranged facing the magnet 5. The first inner diameter is smaller than the second inner diameter, wherein the inner diameter of the sleeve 3 increases in a stepped manner from the rotor to the magnet, thus the inner diameter of the sleeve 3 has a stepped portion. Here, the sleeve 3 can be fitted onto the rotor and can be connected to the rotor for force transmission and / or material connection, for example, by welding and / or pressing.

[0039] The magnet 5 can be connected to the sleeve 3 via the cover portion 2. For this purpose, the cover portion 2 has a circular bottom section with multiple protrusions 2a arranged on its circumference. These protrusions 2a extend from the bottom section along the circumferential side of the magnet 5. The protrusions 2a are integrally designed with the bottom section and are arranged at right angles to the bottom section, and in particular, curved. Advantageously, the protrusions 2a are evenly distributed along the circumferential direction of the bottom section. The height of the protrusions 2a corresponds substantially to the height of the magnet 5.

[0040] According to the first embodiment, the cover portion 2 is arranged in the sleeve 3 and rests on a stepped portion within the sleeve 3 with a bottom section. Here, a protrusion 2a extends from the bottom section to the magnet 5. The protrusion 2a is arranged within the sleeve 3, wherein the sleeve 3 radially surrounds the protrusion 2a in a region of the second diameter. The magnet 5 is placed on the bottom section and held by the protrusion 2a. Here, the magnet 5 is press-fitted to the cover portion 2 and the sleeve 3. For this purpose, the sleeve 3 is pressed onto the protrusion 2a by means of a laser 4. Advantageously, the sleeve 3 has two laser-shrinkable sections that circumferentially surround the cover portion 2. The laser-shrinkable section here refers to a section in which the outer diameter of the sleeve 3 is reduced by means of a laser 4 through laser welding. This process does not form a material bond between the sleeve 3 and the corresponding protrusion 2a. The sleeve 3 is not fully welded, but only 50% to 80% is welded. Here, a weld is formed, which reduces the second inner diameter in the corresponding laser shrinkage section, thereby pressing the sleeve 3 against the cover portion 2 and the magnet 5 arranged therein. This connection technique is also known as laser-induced interference fit.

[0041] Advantageously, the cover portion 2 is made of aluminum, which allows for good heat dissipation during laser welding. This protects the magnet 5 from thermal overload.

[0042] exist Figure 2 The difference between the embodiment of the sensor assembly shown and the first embodiment is that the magnet 5 is arranged between the bottom section of the cover portion 102 and the stepped portion of the sleeve 3. Here, the magnet 5 is placed on the stepped portion. The protrusion 102a of the cover portion 102 extends from the bottom section to the sleeve 3. Here, the magnet 5 is at least partially surrounded by the protrusion 102a in the circumferential direction.

[0043] The thickness of the bottom section is chosen to be thin enough that the magnetic field of magnet 5 is not shielded or is only slightly shielded.

[0044] The protrusion 102a extends into the inner region of the sleeve 3 within the region of the second diameter. Therefore, the protrusion 102a is arranged between the magnet 5 and the sleeve 3. Thus, the sleeve 3 radially surrounds the protrusion 102a within the region of the second diameter.

[0045] The magnet 5 is press-fitted to the cover portion 102 and the sleeve 3. For this purpose, the sleeve 3 is pressed onto the protrusion 102a by means of a laser 4. Advantageously, the sleeve 3 has two circumferentially surrounding laser-shrinkable sections. These laser-shrinkable sections refer to sections in which the outer diameter of the sleeve 3 is reduced by means of the laser 4 through laser welding. This process does not create a material bond between the sleeve 3 and the corresponding protrusion 102a. The sleeve 3 is not fully welded, but only 50% to 80% welded. Here, a weld is formed, which reduces the second diameter in the corresponding laser-pressed sections, thereby pressing the sleeve 3 tightly against the cover portion 102 and the magnet 5 disposed therein.

[0046] exist Figure 3 , Figure 4 and Figure 5 A third embodiment of the sensor assembly 200 is shown in the figure.

[0047] The sensor assembly 200 has a sleeve 203 for connection with the rotor 206, a magnet 5, particularly a neodymium magnet, and a cover portion 202.

[0048] The magnet 5 is preferably designed as a permanent magnet, particularly a neodymium magnet. The magnet 5 is generally disk-shaped and has a circular cross-section. Here, the height of the magnet 5 is less than the diameter of the magnet 5.

[0049] The lid portion 202 is generally cup-shaped. The inner diameter of the lid portion 202 is slightly larger than the diameter of the magnet 5, so that the magnet 5 can be inserted into the lid portion 202. The lid portion 202 is preferably made of stainless steel.

[0050] Sleeve 203 is designed to be generally cup-shaped. The inner diameter of sleeve 203 is large enough that rotor 206 can be introduced into sleeve 203 and can be connected and / or force-transmittingly connected to the material of sleeve 203, for example by welding and / or clamping. Sleeve 203 is preferably made of stainless steel.

[0051] The outer diameter of the sleeve 203 has a stepped portion, wherein the outer diameter of the sleeve 203 gradually decreases from the opening of the sleeve 203 to the bottom section of the sleeve 203. Here, the minimum outer diameter of the sleeve 203 is smaller than the diameter of the magnet 5. The maximum diameter of the sleeve 203 is substantially the same as the diameter of the magnet 5.

[0052] The first side surface of the magnet 5 rests on the outer bottom section of the sleeve 203, and its second side surface is held by the inner bottom section of the cover portion 202. Therefore, the magnet 5 is arranged between the outer bottom section of the sleeve 203 and the inner bottom section of the cover portion 202.

[0053] The cover portion 202 completely covers the sleeve 203 in the region of the sleeve 203's minimum diameter. In the region of the sleeve 203's maximum diameter, the cover portion 202 at least partially covers the sleeve 203. Here, in the region of the sleeve 203's maximum diameter, the cover portion 202 and the sleeve 203 are materially connected and / or force-transmittingly connected to each other, especially by welding or extrusion.

[0054] To secure the magnet 5, the cover portion 202 has a reduced inner diameter in the region of minimum diameter of the sleeve 203, particularly a narrowed portion 204, preferably two narrowed portions 204 spaced apart in the axial direction. Therefore, after the cover portion 202 is connected to the sleeve 203, the wall of the cover portion 202 contracts in the region of reduced diameter, particularly by means of the laser 4. Here, the wall of the cover portion 202 deforms, thereby pressing the magnet 5 onto the sleeve 203.

[0055] The magnet 5 is press-fitted to the cover portion 202 and the sleeve 203. Here, in the region where the diameter of the sleeve 203 decreases, no material bond is formed between the sleeve 203 and the wall of the cover portion 202. The cover portion 202 is not fully welded, but only 50% to 80% is welded. Here, a weld is formed, which reduces the inner diameter of the cover portion 202 in the corresponding narrowing region 204, thereby pressing the sleeve 203 against the cover portion 202 and the magnet 5 disposed therein.

[0056] exist Figure 6 A first variant of the method for manufacturing rotor 206 according to the present invention is shown.

[0057] In the first method step 301, the magnet 5 is positioned or placed on the sleeve 203, especially on the outer bottom section of the sleeve 203.

[0058] In the second method step 302, the cover portion 202 is guided over the magnet 5 and the sleeve 203, so that the magnet 5 is arranged between the cover portion 202 and the sleeve 203, particularly between the outer bottom section of the sleeve 203 and the inner bottom section of the cover portion 202.

[0059] In the third method step 303, the cap portion 202 is made to be force-transmittingly connected and / or material-connected to the sleeve 203 in the region of the maximum diameter of the sleeve 203, particularly by welding and / or extrusion.

[0060] In the fourth method step 304, the cover portion 202 is deformed, particularly contracted, in the region of the minimum outer diameter of the sleeve 203, thereby reducing the inner diameter of the cover portion 202. Advantageously, the wall of the cover portion 202 is laser-contracted using a laser 4. Here, in the region where the diameter of the sleeve 203 is reduced, no material connection is formed between the sleeve 203 and the wall of the cover portion 202. The cover portion 202 is not fully welded, but only 50% to 80% is welded. Here, a weld is formed, which reduces the inner diameter of the cover portion 202 in the region of the corresponding narrowing portion 204, thereby pressing the sleeve 203 against the cover portion 202 and the magnet 5 disposed therein.

[0061] In the fifth method step 305, the sleeve 203 is connected to the rotor 206 by material connection and / or force transmission connection, especially by welding.

[0062] Figure 7 A second variant of the method 400 for manufacturing rotor 206 according to the present invention is shown. Here, in the first method step 401, the sleeve 203 is connected to the rotor 206 material and / or force-transmitting connection.

[0063] In the second method step 402, the magnet 5 is placed on the sleeve 203, especially on the outer bottom section of the sleeve 203.

[0064] In the third method step 403, the cover portion 202 is guided over the magnet 5 and the sleeve 203, thereby arranging the magnet 5 between the cover portion 202 and the sleeve 203, particularly between the outer bottom section of the sleeve 203 and the inner bottom section of the cover portion 202. Then, the cover portion 202 and the sleeve 203 are force-transmittingly connected and / or material-connected, particularly by welding and / or extrusion, in the region of the sleeve 203's maximum diameter.

[0065] In the fourth method step 404, the cover portion 202 is deformed, particularly contracted, in the region of the minimum outer diameter of the sleeve 203, thereby reducing the inner diameter of the cover portion 202. Advantageously, the wall of the cover portion 202 is laser-contracted using a laser 4. Here, in the region where the outer diameter of the sleeve 203 is reduced, no material connection is formed between the sleeve 203 and the wall of the cover portion 202. The cover portion 202 is not fully welded, but only 50% to 80% is welded. Here, a weld is formed, which reduces the inner diameter of the cover portion 202 in the region of the corresponding narrowing portion 204, thereby pressing the sleeve 203 against the cover portion 202 and the magnet 5 disposed therein.

Claims

1. Sensor assembly (1, 100, 200) for the rotor (206) of the motor. Its features are, The sensor assembly (1, 100, 200) has a magnet (5), a cover portion (2, 102, 202) and a sleeve (3, 203). The sleeves (3, 203) are connected to the rotor (206), and the cover portions (2, 102, 202) are connected to the sleeves (3, 203). The magnet (5) is held in the cover portion (2, 102, 202) by a shrink connection, particularly a laser shrink connection.

2. The sensor assembly (1, 100) according to claim 1. Its features are, The cover portion (2, 102) has a bottom section and a protrusion (2a, 102a), wherein the protrusion (2a, 102a) extends along the peripheral side surface of the magnet (5) and holds the magnet (5).

3. The sensor assembly (1, 100) according to claim 2. Its features are, The protrusions (2a, 102a) are arranged in the radial direction between the magnet (5) and the sleeve (3), wherein the sleeve (3) has at least one laser shrinkage section that surrounds in the circumferential direction, such that the protrusions (2a, 102a) are pressed against the magnet (5) by means of the laser shrinkage section.

4. The sensor assembly (1) according to claim 2 or 3. Its features are, The inner diameter of the sleeve (3) has a stepped portion, wherein the bottom section of the cover portion (2) is placed on the stepped portion, thereby the bottom section is arranged between the stepped portion and the magnet (5).

5. The sensor assembly (100) according to claim 2 or 3. Its features are, The inner diameter of the sleeve (3) has a stepped portion, wherein the magnet (5) is placed on the stepped portion, thereby the magnet (5) is arranged between the stepped portion and the bottom section of the cover portion (102).

6. The sensor assembly (200) according to claim 1. Its features are, The lid portion (202) is cup-shaped, wherein the magnet (5) is housed within the lid portion (202).

7. The sensor assembly (200) according to claim 6. Its features are, The outer diameter of the sleeve (203) increases in a stepped manner from the magnet (5) to the rotor (206), wherein the cover portion (202) is arranged on the sleeve (203) and extends from the minimum outer diameter of the sleeve (203) to the maximum outer diameter of the sleeve (203).

8. The sensor assembly (200) according to claim 7. Its features are, The cover portion (202) has a reduced inner diameter, particularly a narrowed portion (204), in the region of the minimum outer diameter of the sleeve (203), and in particular, the cover portion has a laser shrink connection in the region of the reduced inner diameter.

9. The sensor assembly (200) according to any one of claims 6 to 8. Its features are, The cover portion (202) is material-connected and / or force-transmittingly connected to the sleeve (203), particularly in the region of the maximum outer diameter of the sleeve (203).

10. The sensor assembly (1, 100, 200) according to any one of the preceding claims. Its features are, The sleeve (3, 203) is connected to the rotor (206) for force transmission and / or material connection, wherein, in particular, the outer diameter of the rotor (206) is smaller than the outer diameter of the sleeve (3, 203).

11. An electric motor having a rotor (206) and a sensor assembly (100, 200, 300) according to any one of the preceding claims.

12. A method of manufacturing a sensor assembly (1, 100, 200) for a rotor (206), said sensor assembly being particularly a sensor assembly according to any one of claims 1 to 10, said sensor assembly having a magnet (5), a sleeve (3, 203) and a cover portion (2, 102, 202). in, The magnet (5) is introduced into the cover portion (2, 102, 202). Subsequently, the cover portion (2, 102, 202) and / or the sleeve (3, 203) are contracted by means of a laser (4), so that the magnet (5) is held by the cover portion (2, 102, 202).

13. The method for manufacturing sensor assemblies (1, 100, 200) according to claim 12, Its features are, Before laser shrinkage, the cover portion (202) is force-connected and / or material-connected to the sleeve (203).

14. The method for manufacturing sensor assemblies (1, 100, 200) according to claim 12 or 13, Its features are, In the first or last method step, the sleeve (3, 203) and the rotor (206) are connected.

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