Motor assembly with position sensor

Abstract

The invention relates to a motor assembly (1) having a rotor (6) and a sensor assembly (2, 3). The sensor assembly (3) comprises a sensor (3) and a target (2). The target (2) is applied on the surface of the rotor (6), and the sensor (3) is arranged opposite the target (2) on a support cover (5) of the motor (1).

Description

[0001] This application is a divisional application of the invention patent application with application number 201980083820.2, application date December 12, 2019, and name “Motor assembly with position sensor”. Technical Field

[0002] The present invention relates to a motor assembly having a position sensor. Background Art

[0003] Publication DE 3914082 A1 discloses an electronically commutated electric motor having a stator with at least one stator winding, a rotor with magnetized regions, and a sensor element on the stator for detecting the position of the magnetized regions. Summary of the invention

[0004] The invention relates to a motor assembly having a rotor and a sensor assembly. The sensor assembly comprises a sensor and a target, wherein the target is applied on the surface of the rotor, and wherein the sensor and the target are arranged on a bearing cover of the motor opposite to each other.

[0005] This has the advantage that the motor is designed to be very compact. The bearing cover for supporting the rotor shaft of the motor is additionally used to support the sensor. In this way, otherwise unused construction space is saved and the components for determining the rotor position are arranged compactly in the motor.

[0006] In the design of the motor assembly, the sensor is mounted on the support cover by means of a separating disk. The separating disk ensures that, in the case of a metallic support cover, no interference occurs between the electronics of the sensor and the support cover. The separating disk also ensures mechanical coupling when fastened to the support cover.

[0007] In another embodiment of the motor assembly, the sensor and the separating disk surround the rotor shaft of the rotor. In this case, a bearing of the rotor shaft is arranged radially between the rotor shaft on the one hand and the sensor and the separating disk on the other hand. In this case, in particular, an axial section of the bearing cover is provided between the sensor and the separating disk on the one hand and the bearing on the other hand, which axial section extends in the axial direction of the motor.

[0008] The arrangement of the components around the rotor shaft has the advantage that the components can be accommodated in a space-saving manner.

[0009] In an advantageous embodiment of the motor assembly, the axial section of the bearing cover is designed in the form of a notch. The bearing is fixed. In this way, the bearing can be displaced toward the direction close to the rotor and can be arranged in a space-saving manner. The structural length of the motor is shortened by positioning the bearing in the direction close to the rotor.

[0010] Furthermore, in the motor assembly, the sensor and the isolating disk can be accommodated in a cavity of the motor assembly in a fixed position. Here, the cavity is at least partially delimited by the support cover, the rotor and the isolating body of the stator winding of the stator. The motor provided has a corresponding cavity in structure. Since the sensor used is in principle constructed to be very flat, the cavity can be utilized by introducing the sensor and the isolating disk into the cavity, and the cavity does not remain unutilized. Therefore, the motor as a whole can be designed to be smaller in terms of its total volume. The advantage of fixed position arrangement on the support cover is that the sensor is then arranged on a stable component in the motor cavity and a reliable zero point is therefore ensured by positioning and fixing the sensor.

[0011] In other embodiments of the motor assembly, the target is arranged on a surface of the rotor facing the cavity and is rotationally movable in the cavity relative to the sensor, in particular rotationally movable together with the rotor.

[0012] In one embodiment of the motor assembly, the target is connected to the rotor by means of a connection, wherein the connection is in particular a rivet, a clip, a hook, an ultrasonic rivet or a rivet-free rivet. The fixed connection between the target and the rotor prevents possible misalignment between the rotor and the target, which could lead to falsification of the measurement result when the rotor performs a rotational movement.

[0013] In an advantageous embodiment, the target and the sensor are designed in the form of an annular disk with a central opening. In this case, the outer radius of the target is smaller than or equal to the outer radius of the sensor, and the inner radius of the target is greater than or equal to the inner radius of the sensor. In this way, a good superposition of the sensor surface with the target surface can be ensured, thereby generating a sufficiently good measurement signal, especially since in the inductive measuring principle the measurement depends on the superposition or overlap of sensor and target. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following is an explanation of the embodiments of the present invention with reference to the accompanying drawings.

[0015] Figure 1 A first view of a motor assembly with a position sensor is shown.

[0016] Figure 2 A second view of the motor assembly with the position sensor is shown.

[0017] Figure 3 A third view of the motor assembly with the position sensor is shown.

[0018] Figure 4 – Figure 7 Alternative fixing means between the target and the rotor of the motor are shown respectively. DETAILED DESCRIPTION

[0019] Figure 1 The motor assembly 1 is shown. The motor assembly 1 comprises a motor housing 8 and a bearing cover 5. Two ball bearings 9 supporting the rotor shaft 7 are supported on one side at the bearing cover 5 and on the other side at the motor housing 8. In other words, the ball bearings 9 are held, in particular fixed, by the bearing cover 5 and the motor housing 8. The rotor shaft 7 supports the rotor 6. The rotor 6 is connected to the rotor shaft 7 in such a way that the rotor can perform a rotational movement together with the rotor shaft 7 about the longitudinal axis of the rotor shaft 7. The longitudinal axis of the rotor shaft 7 extends from the motor housing 8 to the bearing cover 5, which is indicated by the direction x.

[0020] The rotor 6 is surrounded by a corresponding stator 16, which has a corresponding stator winding 11. A target 2 is arranged on the rotor 6. The target 2 is arranged on the upper side of the rotor 6 facing the support cover 5. The target 2 is part of a sensor assembly, which includes a sensor 3 in addition to the target 2. The sensor 3 is connected to the support cover 5 via an isolating disk 4. The isolating disk isolates the electronics of the sensor 3 in the direction of the support cover 5 and enables fixing.

[0021] The target 2, the sensor 3 and the isolating disk 4 are arranged in an annular shape, in particular as disks. A circular opening is provided centrally in the target 2, the sensor 3 and the isolating disk 4. The size of the circular opening is determined in such a way that the rotor shaft 7, the bearing 9 and the axial section 18 can be accommodated in the circular opening.

[0022] The target 2 has a circular opening with an inner radius greater than or equal to the inner radius of the circular opening of the sensor 3 , and the target 2 has a circular opening with an outer radius less than or equal to the outer radius of the sensor 3 .

[0023] Here, the sensor 3 and the target 2 work on the inductive measurement principle, wherein the sensor includes an excitation coil and a detection coil. The target includes a conductive area and a non-conductive area. When the target 2 rotates, the conductive area of ​​the target 2 and the non-conductive area of ​​the target 2 alternately sweep across the sensitive surface of the sensor 3. As a result, a variable voltage is induced in the detection coil, which characterizes the rotational motion as a signal. Therefore, the position of the rotor relative to the stator can be determined.

[0024] A part of the bearing cover 5 and the upper ball bearing 9 extend into the circular openings of the sensor 3 and the isolating disk 4. The bearing cover 5 has a radial region 17 and an axial region 18 in a central section extending toward the rotor shaft 7. The radial region 17 has a radial region 17 and an axial region 18 orthogonal to the radial region 17. Figure 1, which is indicated by the direction r. The axial region 18 adjoins the radial region 17 and extends in the direction x parallel to the rotor shaft 7 in the direction of the motor housing 8. The axial region 18 of the bearing cover 5 forms a recess in which the ball bearing 9 is supported. The axial region 18 and the ball bearing 9 are accommodated in the circular openings of the sensor 3 and the isolating disk 4.

[0025] Here, the lower end of the axial section 18 of the ball bearing 9 and the bearing cap 5 can either be closed by the underside of the sensor 3 or alternatively protrude through the opening of the separating plate 4 and the sensor 3. In this case, the axial region 18 and the ball bearing 9 can also be accommodated in a proportional manner in a circular opening of the target 2.

[0026] The rotor position of the rotor 6 can be determined by means of a sensor arrangement comprising a target 2 and a sensor 3. A relative deflection in the form of a rotational movement of the target 2 relative to the sensor 3 causes a characteristic signal which can be correlated with the rotor position.

[0027] The target 2 is fixedly connected to the rotor 6. The sensor 3 is connected to the bearing cover 5 via a separating plate. Since the rotor 6 rotates during operation, in particular with the rotor shaft 7, the target 2 rotates while being fixedly connected to the rotor 6. The rotation of the target 2 relative to the sensor 3, which is fixedly connected to the bearing cover 5, is measured by means of the sensor 3.

[0028] In order to be able to acquire the sensor signal, the sensor 3 is connected to the plug 14 by means of the contact element 13. For example, a cable 13 can be connected to the sensor 2, which is connected to the plug 14. The plug 14 can then be connected to the controller. Of course, a direct connection of the sensor 2 to the controller is also conceivable, wherein the plug 14 is omitted in this case.

[0029] exist Figure 2 , how the target 2 extends around the rotor axis 7, wherein a cross-sectional view is shown in which the support cap 5 is hidden. The target 2 is connected to the rotor 6 via a fastening device 15. The fixed connection between the target 2 and the rotor 6 ensures that no misalignment can occur between the rotor 6 and the target 2, which could impair the quality of the measurement. Figure 2 In the embodiment, the connection between the target 2 and the rotor 6 is a riveted connection. For this purpose, the target 2 is fixed to the rotor 6 by means of rivets 15. Of course, a connection by a plurality of rivets can also be realized.

[0030] Figure 3 It is further shown how the target 2, the sensor 3 and the separating disk 4 are arranged relative to the bearing cover 5 and the bearing 9 and the rotor shaft 7. The substantially parallel arranged target 2 and the sensor 3 are arranged offset to one another by a distance 21. This distance can be provided such that the measurement by means of the inductive measuring method works reliably.

[0031] Target 2, sensor 3 and separating disk 4 are all arranged concentrically around rotor shaft 7 and surround rotor shaft 7. As already mentioned, sensor 3 and separating disk 4 also surround lower section 18 of bearing cover 5 and bearing 9 accommodated in bearing cover 5.

[0032] Depending on the length of the section 18 and the bearing 9 in the x-direction, they can also extend in the x-direction into the central opening of the target 2, as has already been done with the aid of Figure 1 It is also conceivable that the section 18 and the bearing 9 do not extend in the x direction into the central opening of the target 2. The axial section 18 of the bearing cover 5 and the bearing 9 should not contact the rotor 6 so that the rotor can rotate freely relative to the bearing cover 5 and the bearing 9.

[0033] The sensor 3 is connected to the separating disk 4. The separating disk 4 is in turn fixed to the radial section 17 of the support cover 5. The fixing can be achieved by heat-stitching, and crimping technology or snap-on or riveted connections are also conceivable.

[0034] The sensor 3, the target 2 and the isolating disk 4 are arranged as a stack, wherein the sensor 3 and the isolating disk 4 are arranged in a fixed position on the support cover 5, and the target 2 is arranged to rotate together with the rotor 6, and wherein an air gap 21 is provided between the sensor 3 and the target 2. The sensor 3, the target 2 and the isolating disk 4 are accommodated in a cavity 22 between the support cover 5, the rotor 6 and the isolating body 10 of the stator winding 11.

[0035] An alternative fastening possibility between the target 2 and the rotor 6 is Figure 4 – Figure 7 The object. Figure 4 , in which the target 2 is connected to the rotor 6 by an ultrasonic riveting. Here, the protruding section of the rotor 6 beyond the target 2 is deformed by energy input by means of an ultrasonic punch, which results in a form-fitting connection between the target 2 and the rotor 6. The wave shape in the punch is to be understood as an example.

[0036] Figure 5 and Figure 6 A snap-on connection is shown, in which the connection between the target 2 and the rotor 6 is achieved by means of a differently shaped connecting element 15. For this purpose, when a force is applied to the connecting element 15, the connecting element is pressed into an opening which is formed proportionally by the target 2 and the rotor 6. In the final assembly position of the connecting element 15, the connecting element is deformed so that a locking or hooking ( Figure 5 ), or is held by shape fit or friction. Here, feasible connecting element 15 is a hook, a ball, a pliers, a clamp. Other designs are feasible. Figure 5 The left part shows a plug which is pressed into the joint opening formed by the target 2 and the rotor 6. The plug is held in place by force transmission, as in Figure 5 As shown in the right part.

[0037] exist Figure 6 In the embodiment, the connecting element 15 has locking lugs 20 on the side, which give in their position when inserted. Once the connecting element 15 is in the final position, the locking lugs grip corresponding elements in / at the rotor 6, which causes the rotor 6 and the target 2 to be fixed relative to each other.

[0038] exist Figure 7 , a connection method is shown in which the rotor 6 and the target 2 are connected to each other by means of nailless riveting via material deformation. For this purpose, a force input must be introduced in the direction of the arrow during the connection.

Claims

1. Motor assembly, including: a rotor including a rotor shaft defining an axis; Support cover; as well as a sensor assembly having a sensor and a target, in, The target is disposed on a surface of the rotor, The sensor is arranged on the support cover opposite to the target, and The support cap is configured to support a bearing such that the bearing is positioned between at least a portion of the sensor assembly and the rotor in a direction orthogonal to the axis.

2. The motor assembly according to claim 1, wherein: The motor assembly further comprises a separating disk, wherein the sensor is mounted on the bearing cover by means of the separating disk.

3. The motor assembly according to claim 2, wherein: The motor assembly includes the bearing, The sensor and the isolation disk surround the rotor shaft, and The bearing is disposed radially relative to the axis between (i) the rotor shaft and (ii) the sensor and the isolation disk.

4. The motor assembly according to claim 3, wherein: The sensor and the isolation disk are fixedly accommodated in the cavity of the motor assembly, wherein: The cavity is delimited at least partially by the bearing cover, the rotor and the insulation of the stator winding of the stator.

5. The motor assembly according to claim 4, wherein: The target is disposed on a surface of the rotor facing the cavity and is rotatable relative to the sensor in the cavity.

6. The motor assembly according to claim 5, wherein: The target is rotatable with the rotor relative to the sensor.

7. The motor assembly according to claim 3, wherein: An axial section of the bearing cap extends between (i) the sensor and the separating disk and (ii) the bearing.

8. The motor assembly according to claim 7, wherein: An axial section of the bearing cap is notch-shaped and secures the bearing.

9. The motor assembly according to claim 7, wherein: The bearing cap is configured to be positioned in a motor housing and to support the bearing in the motor housing.

10. The motor assembly according to claim 7, wherein: At least a portion of the axial section of the bearing cap is located directly radially inwardly of the target.

11. The motor assembly according to claim 1, wherein: The target is connected to the rotor.

12. The motor assembly according to claim 11, wherein: The target is connected to the rotor by any one of rivets, clips, hooks, ultrasonic riveting points, and nail-free riveting points.

13. The motor assembly of claim 1, wherein: The target and the sensor are annular and have a central opening, The outer radius of the target is less than or equal to the outer radius of the sensor, and The inner radius of the target is greater than or equal to the inner radius of the sensor.

14. The motor assembly of claim 1, wherein: The bearing cap is configured to be located completely radially outside the bearing.

15. Motor assembly, including: Rotor; Support cover; as well as a sensor assembly having a sensor and a target, in, The target is disposed on a surface of the rotor, The sensor is arranged on the support cover opposite to the target, and An axially extending section of the bearing cap supports a bearing and is located between at least a portion of the sensor assembly and the bearing.

16. The motor assembly of claim 15, wherein: The bearing cap is located completely radially outside the bearing.

17. A motor assembly comprising: Rotor; Support cover; as well as a sensor assembly having a sensor and a target, in, The target is disposed on a surface of the rotor, The sensor is arranged on the support cover opposite to the target, The target and sensor are annular and have a central opening, and (i) the outer radius of the target is smaller than the outer radius of the sensor, and the inner radius of the target is greater than or equal to the inner radius of the sensor, or (ii) The outer radius of the target is equal to the outer radius of the sensor, and the inner radius of the target is greater than the inner radius of the sensor.

18. The motor assembly of claim 17, wherein: The support cap includes a radially extending section; The sensor is mounted to the radially extending section; and The bearing cap includes an axially extending section extending directly from the radially extending section along an inner side of the sensor.

19. The motor assembly of claim 18, wherein: The motor assembly includes a first bearing; and The axially extending section extends along an outer side of an outer ring of the first bearing.

20. The motor assembly of claim 19, wherein: The motor assembly further comprises: a motor housing supporting the bearing cover; and A second bearing is directly supported by the motor housing.

Images