motor unit

Abstract

A motor unit includes a motor and a resolver that detects a rotation angle of the motor. The motor includes a stator and a rotor that is disposed inward of an inner peripheral surface of a stator core and is rotatably supported. The resolver includes a resolver rotor that is attached to a shaft of the rotor, i.e., a rotor shaft, and is rotatable with the rotor shaft, and a resolver stator. The motor unit also includes a shield plate that is made of a magnetic material and is disposed between the rotor and the resolver stator in such a manner that the resolver stator is kept at a prescribed distance.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a motor unit having a motor and a rotary transformer for detecting the rotation angle of the motor. Background Technology

[0002] A rotary transformer is used as a sensor to detect the rotational speed (rotation angle) related to the drive motor and / or generator motor mounted on a vehicle.

[0003] Japanese Patent Application Publication No. 2011-217519 discloses an electromagnetic shielding structure for shielding electromagnetic noise generated from the coil ends of a motor stator. According to Japanese Patent Application Publication No. 2011-217519, a shielding plate is provided between the coil end of the coil wound on the stator of the motor, which protrudes axially in the stator, and the stator core of a rotary transformer. Summary of the Invention

[0004] The need for miniaturization of motor units has spurred the miniaturization of coil ends, resulting in a closer distance between the rotary transformer and the motor rotor compared to the distance between the rotary transformer and the coil ends. Given this situation, the shielding structure disclosed in Japanese Patent Application Publication No. 2011-217519, which involves placing a shielding plate between the coil ends and the stator core of the rotary transformer, does not adequately shield against electromagnetic noise generated from the rotor or the gap between the rotor and the stator.

[0005] This specification discloses a motor unit comprising a motor and a rotary transformer for detecting the rotation angle of the motor.

[0006] The motor has the following features:

[0007] A stator having a stator core and coils mounted on the stator core; and

[0008] The rotor is positioned further inward than the inner circumferential surface of the stator core and is rotatably supported.

[0009] The rotary transformer has the following features:

[0010] A rotary transformer rotor, which is mounted on the shaft of the rotor, i.e., the rotor shaft, and is capable of rotating together with the rotor shaft; and

[0011] A rotary transformer stator having a rotary transformer stator core and a rotary transformer coil, the rotary transformer stator core being formed in a ring shape and configured to surround the outer peripheral surface of the rotary transformer rotor, and the rotary transformer coil being mounted on the rotary transformer stator core.

[0012] The motor unit also includes a shielding plate made of a magnetic material, which is configured between the rotor and the rotary transformer stator at a predetermined distance from the rotary transformer stator.

[0013] According to the structure, by using a shielding plate disposed between the rotor and the stator of the rotary transformer, electromagnetic noise generated from the rotor or the gap between the rotor and the stator can be shielded, thereby suppressing false detections of the rotary transformer. Attached Figure Description

[0014] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:

[0015] Figure 1 It is a cross-sectional view that simply represents the structure of the motor unit.

[0016] Figure 2 It is an exploded perspective view showing a portion of the shielding plate, the stator of the rotary transformer, and the housing.

[0017] Figure 3 This is a partial sectional view showing an example of a state in which the shielding plate of the fastening component and the stator of the rotary transformer are fixed to the housing.

[0018] Figure 4 This indicates the state in which the shielding plate and the stator of the rotary transformer are fixed to the housing by fastening components, and is related to... Figure 3 A partial sectional view of a different example.

[0019] Figure 5 It means and Figure 2 Three-dimensional views of the shielding plates involved in different examples.

[0020] Figure 6 This is a diagram used to illustrate the effects of this embodiment. Detailed Implementation

[0021] The main features of the embodiments described below are listed below. These features can be combined arbitrarily.

[0022] According to the motor unit disclosed in this specification, the shielding plate can cover the entire area of ​​the rotary transformer stator opposite to the rotor.

[0023] According to the structure, the shielding plate covers the entire area of ​​the rotary transformer stator opposite to the rotor between the rotor and the rotary transformer stator, thus accurately protecting the rotary transformer from electromagnetic noise.

[0024] According to the motor unit disclosed in this specification, the shielding plate and the rotary transformer stator can be fixed to the housing that houses the motor by a common fastening component.

[0025] According to the structure described, the shielding plate can be positioned relative to the stator of the rotary transformer using a simple structure.

[0026] According to the motor unit disclosed in this specification, the shielding plate may further include a shielding side plate disposed between the coil end protruding from the stator core in an axial direction parallel to the rotor shaft and the stator of the rotary transformer.

[0027] According to the structure described, the rotary transformer can also be protected by shielding electromagnetic noise generated from the coil ends through the shielding side plate.

[0028] According to the motor unit disclosed in this specification, the distance between the end of the shield plate opposite to the rotor shaft and the rotor shaft can be less than the distance between the outer circumferential surface of the rotary transformer rotor and the rotor shaft.

[0029] According to the structure, by covering the rotor and the stator of the rotary transformer with a shielding plate as close as possible to the rotor shaft, the shielding effect on the electromagnetic noise of the rotary transformer can be further improved.

[0030] The embodiments will be described with reference to the accompanying drawings. The drawings are merely illustrative, and the embodiments are not limited to the content shown. Furthermore, since the drawings are illustrative, some parts may be omitted.

[0031] Figure 1 The structure of the motor unit 10, which includes the motor 20 and a rotary transformer 30 for detecting the rotation angle of the motor 20, is simply represented by a cross-section through the central axis Ax of the motor 20. The motor unit 10 is housed in a housing 11. A portion of the structure of the motor unit 10 may exist outside the housing 11. The motor 20 is driven by an external power supply. The concept of a motor includes various types such as DC (direct current) motors, AC (alternating current) motors, stepper motors, and servo motors.

[0032] Motor 20 includes a stator 21 and a rotor 24. The stator 21 includes a cylindrical stator core 22 fixed within a housing 11 and coils 23 mounted on the stator core 22. Hereinafter, the radial direction, circumferential direction, and axial direction of motor 20 will be simply referred to as radial, circumferential, and axial, respectively. The axial direction is the direction parallel to the central axis Ax. The radial direction is the direction perpendicular to and extending radially from the central axis Ax. In the radial direction, the side closer to the central axis Ax is the radially inner side, and the side farther from the central axis Ax is the radially outer side. In this embodiment, the cylindrical or annular shape includes not only cases where the shape in a cross-section perpendicular to the axial direction is circular, but also cases where the shape is close to a polygonal shape.

[0033] The coil 23 is formed by winding a coil wire, which serves as a conductor, around the stator core 22. In this embodiment, the method of mounting or winding the coil 23 relative to the stator core 22 is not particularly limited. The coil 23 is wound around the stator core 22 and extends circumferentially. The end face of the stator core 22 facing axially is referred to as the first end face 22a. Figure 1 In this diagram, the end face (second end face) of the stator core 22 facing the opposite side of the axial direction is omitted. A portion of the coil 23 protrudes axially from these first end faces 22a and second end faces, respectively. Thus, the portion of the coil 23 protruding from the first end face 22a and second end face, respectively, is called the coil end 23a. Figure 1 Since coil 23 is simply shown, only the coil end 23a of coil 23 is shown in the result.

[0034] The rotor 24 is positioned radially inward and rotatably supported compared to the inner circumferential surface of the stator core 22. The rotor 24 is rotatably supported about a central axis Ax, for example, by bearings (not shown) fixed to the housing 11. The stator 21 and rotor 24 are concentrically arranged about the central axis Ax. The shaft of the rotor 24 is referred to as the rotor shaft 25. The rotor shaft 25 extends axially beyond the rotor 24. By supplying electricity to the coil 23, the rotor 24, including the rotor shaft 25, rotates under the influence of a magnetic field. The rotation of the rotor shaft 25 is transmitted to the axle of a wheel via a power transmission mechanism (not shown).

[0035] To control the wheel's speed or torque, high-precision detection of the rotation angle of the rotor shaft 25 is required. A rotary transformer 30 is a sensor used to detect the rotation angle of the rotor shaft 25. The rotary transformer 30 includes a rotary transformer rotor 31 and a rotary transformer stator 32. The rotary transformer rotor 31 is mounted on the rotor shaft 25 and can rotate with it. Specifically, the rotary transformer rotor 31 is annular and fixed to the rotor shaft 25 with its inner side inserted through it.

[0036] The rotary transformer stator 32 includes a rotary transformer stator core 33 and a rotary transformer coil 34 mounted on the rotary transformer stator core 33. The rotary transformer stator core 33 is formed in a ring shape. The rotary transformer stator core 33 is configured to surround the outer peripheral surface of the rotary transformer rotor 31. That is, the rotary transformer stator 32 and the rotary transformer rotor 31 are concentrically arranged with respect to the central axis Ax. The rotary transformer coil 34 is wound on the rotary transformer stator core 33 in a manner substantially similar to that of the stator core 22 and the coil 23. In this embodiment, the function or role of the rotary transformer 30 and its method of use are described in general terms, and the specific details are omitted.

[0037] The motor unit 10 includes a shielding plate 40 made of a magnetic material, which is disposed between the rotor 24 and the rotary transformer stator 32 at a predetermined distance from the rotary transformer stator 32. The magnetic material is, for example, iron. Other examples of magnetic materials include nickel or cobalt. The shielding plate 40 is configured not to contact the rotary transformer stator 32. Figure 1 The shielding plate 40 is axially positioned between the rotor 24 and the rotary transformer stator 32. With this structure, electromagnetic noise generated from the rotor 24 or the gap between the rotor 24 and the stator 21 is shielded by the shielding plate 40, thus suppressing false detections of the rotation angle of the rotary transformer 30 caused by electromagnetic noise. This embodiment is particularly useful when the distance between the rotary transformer 30 and the rotor 24 is reduced due to the need for miniaturization of the motor unit 10.

[0038] like Figure 1 As shown, the shielding plate 40 covers the entire area of ​​the stator 32 of the rotary transformer that faces the rotor 24, that is, the entire area facing the rotor 24 in the axial direction. With this structure, the shielding plate 40 can accurately protect the rotary transformer 30 from electromagnetic noise generated from the rotor 24. As a variation, a structure is also envisioned in which a portion of the area of ​​the stator 32 facing the rotor 24 is not covered by the shielding plate 40.

[0039] according to Figure 1The shielding plate 40 has an approximately L-shaped cross-section, and its shape covers at least a portion of the radially opposed surface of the stator 32 of the rotary transformer, which is opposite to the coil end 23a. Specifically, the shielding plate 40 also includes a shielding side plate 42 disposed between the stator 32 and the coil end 23a protruding axially from the stator core 22. The shielding side plate 42 can also shield the rotary transformer 30 from electromagnetic noise generated from the coil end 23a. For convenience, the surface of the shielding plate 40 with the shielding side plate 42 is referred to as the rotor opposing plate 41. That is, "the shielding plate 40 disposed between the rotor 24 and the stator 32 of the rotary transformer at a predetermined distance from the stator 32" essentially refers to the rotor opposing plate 41.

[0040] according to Figure 1 The distance (radial distance) between the end 44 of the shielding plate 40 (rotor opposing plate 41) opposite to the rotor shaft 25 and the rotor shaft 25 is less than the distance (radial distance) between the outer peripheral surface (the surface opposite to the stator core 33 of the rotary transformer) of the rotary transformer rotor 31 mounted on the rotor shaft 25 and the rotor shaft 25. That is, between the rotor 24 and the rotary transformer stator 32, the shielding plate 40 covers a position as close as possible to the rotor shaft 25. This further improves the shielding effect against electromagnetic noise from the rotary transformer 30.

[0041] Figure 2 An exploded perspective view shows the shielding plate 40, the rotary transformer stator 32, and a portion of the housing 11. The shielding plate 40 is generally formed in a ring shape, corresponding to the ring-shaped rotary transformer stator 32, to cover the rotary transformer stator 32. Figure 2 The shielding plate 40 shown includes a rotor opposing plate 41 and a shielding side plate 42. Although in Figure 2 Omitted in the middle, but Figure 2 From a viewpoint, the rotor 24 is positioned higher than the rotor opposing plate 41, and the rotor shaft 25 and the rotary transformer rotor 31 are located radially inward relative to the rotary transformer stator 32.

[0042] In the above configuration where the shielding plate 40 does not contact the stator 32 of the rotary transformer, it can simply be fixed inside the housing 11 by some kind of fixing mechanism. As an example, the shielding plate 40 and the stator 32 of the rotary transformer are fixed to the housing 11 by a common fastening component. Figure 2 The bolt 50 shown is an example of a fastening component. According to... Figure 2 On the rotor opposing plate 41 of the shielding plate 40, a plurality of recesses 43, recessed axially toward the stator 32 of the rotary transformer, are formed at constant intervals along the circumference. In each of the recesses 43, a hole 43a is provided for inserting a bolt 50 (see reference). Figure 3 and Figure 4The bolt 50 is inserted axially through multiple holes 32a in the stator 32 of the rotary transformer. Furthermore, within the housing 11, a boss 12 for inserting and screwing the bolt 50 is erected axially. Therefore, a common bolt 50 is inserted from the rotor opposing plate 41 side into the aligned holes 43a, 32a, and boss 12, and the bolt 50 is screwed onto the boss 12. Thus, the shielding plate 40 and the rotary transformer stator 32 are fixed to the housing 11.

[0043] The motor unit 10 may include an intermediate component 60 made of a non-magnetic material, positioned between the shielding plate 40 and the rotary transformer stator 32, holding the shielding plate 40 at a predetermined distance from the rotary transformer stator 32. The non-magnetic material is unmagnetized, particularly a metallic material, such as aluminum or stainless steel. The magnetic shielding plate 40, maintained at a predetermined distance from the rotary transformer stator 32 by the non-magnetic intermediate component 60, is positioned between the rotor 24 and the rotary transformer stator 32. As a result, the shielding plate 40 magnetically blocks the rotary transformer stator 32, accurately shielding electromagnetic noise generated from the rotor 24 or the gap between the rotor 24 and the stator 21, and suppressing false detections of the rotary transformer 30.

[0044] Figure 3 The image shows a simplified example of a state where the transformer stator 32 is fixed to the housing 11 by the fastening component shielding plate 40 and the rotary transformer stator 32, through a partial sectional view. Figure 3 and Figure 4 In the diagram, only the boss 12 is shown as part of the housing 11; other details are omitted. Figure 3 In this design, the shielding plate 40 and the intermediate component 60 are pre-formed covering materials that are joined together. That is, by integrally molding the covering material that bonds the layers of magnetic materials to the layers of non-magnetic materials, a process is achieved as described above. Figure 2 , Figure 3 The component consists of a shielding plate 40 and an intermediate component 60, as shown in the diagram. Figure 3 On the side of the shielding plate 40 facing the rotary transformer stator 32, an intermediate member 60 extends across the entire surface. The thickness of the intermediate member 60 maintains a constant distance between the shielding plate 40 and the rotary transformer stator 32. That is, the intermediate member 60 is sandwiched between the shielding plate 40 and the rotary transformer stator 32. According to... Figure 3 The intermediate component 60 is in contact with the stator core 33 of the rotary transformer. The intermediate component 60 may or may not be in contact with the coil 34 of the rotary transformer.

[0045] according to Figure 3Hole 43a penetrates the shielding plate 40 and the intermediate component 60. Hole 32a penetrates the stator core 33 of the rotary transformer stator 32. Therefore, a common bolt 50 is inserted into the aligned holes 43a, 32a, and boss 12, and the bolt 50 is screwed onto the boss 12. Thus, the shielding plate 40, the intermediate component 60, and the rotary transformer stator 32 are fixed to the housing 11. In this way, by using a covering material, the shielding plate 40 can be easily and reliably held at a predetermined distance from the rotary transformer stator 32. Although the figures are omitted, it can be understood that the bolt 50 is screwed onto the holes 43a, 32a, and boss 12 through the formed threads and thread grooves, respectively.

[0046] Figure 4 In the partial sectional view, the state in which the transformer stator 32 is fixed to the housing 11 by the fastening component shielding plate 40 and the rotating transformer stator 32 is simply shown. Figure 3 Different examples. Regarding Figure 4 , to Figure 3 The differences will be explained. Figure 4 In the middle, shielding plate 40 is not a covering material. According to Figure 4 The intermediate component 60 is a non-magnetic washer through which the bolt 50 is inserted. That is, the common bolt 50 is inserted into the pre-aligned hole 43a, the annular washer (intermediate component 60), the hole 32a, and the boss 12, and the bolt 50 is screwed relative to the boss 12. Thus, the shielding plate 40, the intermediate component 60, and the rotary transformer stator 32 are fixed to the housing 11. By using the washer, the shielding plate 40 can be inexpensively held at a predetermined distance from the rotary transformer stator 32.

[0047] A hole 43a is formed in the shielding plate 40. The hole 43a allows electromagnetic noise to pass through, which can reduce the shielding effect of the shielding plate 40. To address this, a bolt 50 is formed as a magnetic material such as iron, the same as the shielding plate 40, and the bolt 50 is inserted into the hole 43a. As a result, the hole 43a is blocked by the head of the bolt 50, thereby maintaining the shielding effect of the shielding plate 40.

[0048] In this embodiment of the invention, a structure may be included that maintains the distance between the shielding plate 40 and the stator 32 of the rotary transformer by means of a spacer or other component other than a non-magnetic intermediate component 60. The spacer may be, for example, a resin component. Where a secure and stable fixation of the shielding plate 40 by bolts 50 is desired, the intermediate component 60 as described above is preferred over a resin spacer.

[0049] Figure 5 In, with Figure 2 From the same viewpoint, a stereoscopic view shows an example of the shielding plate 40 involved. Figure 5 The shielding plate 40 shown has the same characteristics as the reference plate. Figures 1 to 4 The shielding plate 40 described has essentially the same characteristics. According to Figure 5 The shielding plate 40 has a rotor opposing plate 41, on which a plurality of holes 43a are formed at constant intervals along the circumferential direction. Figure 5 The shielding plate 40 shown does not have a shielding side plate 42. That is, the shielding plate 40 can be a structure without a shielding side plate 42.

[0050] Figure 6 This is a diagram illustrating the effects of this embodiment. Figure 6 The graph represents the magnitude (error Y) of the detection error based on the rotation angle of the rotary transformer 30, corresponding to the axial distance X from the rotor 24 to the rotary transformer stator 32. Figure 6 In the diagram, the solid line represents the error Y without the shielding plate 40 of this embodiment, and the double-dotted line represents the error Y with the shielding plate 40 of this embodiment. Figure 6 In the diagram, the single-dotted line represents the error Y when the shielding plate 40 is in contact with the stator 32 of the rotary transformer. According to... Figure 6 If the shielding plate 40 of the magnetic material is in contact with the stator 32 of the rotary transformer, the shielding effect on electromagnetic noise is significantly reduced, and the error Y is larger than that without the shielding plate 40. According to... Figure 6 When the distance X is less than or equal to the specified value X1, the error Y without the shielding plate 40 is greater than the error Y with the shielding plate 40. Furthermore, the difference between the error Y without the shielding plate 40 and the error Y with the shielding plate 40 increases as the distance X (less than or equal to the specified value X1) decreases. Figure 6 It can also be considered that this embodiment performs well in the case of the close proximity between the rotary transformer 30 and the rotor 24 due to the need for miniaturization of the motor unit 10.

[0051] The above provides a detailed description of specific examples of the technology disclosed in this specification. However, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples illustrated above. Furthermore, the technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. Moreover, the technology illustrated in this specification or drawings simultaneously achieves multiple objectives, wherein achieving one of these objectives is itself technically useful.

Claims

1. A motor unit comprising a motor and a rotary transformer for detecting the rotation angle of the motor, characterized in that, The motor has the following features: A stator having a stator core and coils mounted on the stator core; and The rotor, which is positioned further inward than the inner circumferential surface of the stator core, is rotatably supported. The rotary transformer has the following features: A rotary transformer rotor, which is mounted on the shaft of the rotor, i.e., the rotor shaft, and is capable of rotating together with the rotor shaft; and A rotary transformer stator has a rotary transformer stator core and rotary transformer coils. The rotary transformer stator core is formed in a ring shape and configured to surround the outer circumferential surface of the rotary transformer rotor. The rotary transformer coils are mounted on the rotary transformer stator core. The motor unit also includes a shielding plate made of a magnetic material, which is configured between the rotor and the stator of the rotary transformer at a predetermined distance from the stator.

2. The motor unit according to claim 1, characterized in that, The shielding plate covers the entire area of ​​the stator of the rotary transformer opposite to the rotor.

3. The motor unit according to claim 1, characterized in that, The shielding plate and the rotary transformer stator are secured to the housing that houses the motor by a common fastening component.

4. The motor unit according to claim 1, characterized in that, The shielding plate also includes a shielding side plate, which is disposed between the end of the coil protruding from the stator core in an axial direction parallel to the rotor shaft and the stator of the rotary transformer.

5. The motor unit according to claim 1, characterized in that, The distance between the end of the shielding plate opposite to the rotor shaft and the rotor shaft is less than the distance between the outer circumferential surface of the rotary transformer rotor and the rotor shaft.

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