motor unit

Abstract

In order to suppress false detection based on a resolver, it is necessary to shield electromagnetic noise generated from a rotor or a gap between the rotor and a stator. A motor unit has a motor and a resolver that detects a rotation angle of the motor. The motor has a stator and a rotor that is disposed at a position more inside than an inner peripheral surface of a stator core and is rotatably supported. The resolver has a resolver rotor that is mounted on a rotor shaft that is a shaft of the rotor and is rotatable with the rotor shaft, and a resolver stator. The motor unit further has a shield plate that is made of a magnetic body and is disposed between the rotor and the resolver stator, and an intermediate member that is interposed between the shield plate and the resolver stator, holds the shield plate at a position separated by a prescribed distance from the resolver stator, and is made of a non-magnetic body.

Description

Technical Field

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

[0002] A resolver is used as a sensor to detect the rotational speed (rotation angle) of the drive and / or generator motors mounted on a vehicle.

[0003] Patent Document 1 discloses an electromagnetic shielding structure for shielding electromagnetic noise generated from the coil ends of a motor stator. According to Patent Document 1, a shielding plate is provided between the coil ends of the coil wound on the stator of the motor, which protrude axially toward the stator, and the stator core of a rotary transformer.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2011-217519 Summary of the Invention

[0005] The miniaturization requirements of motor units have spurred the miniaturization of the coil ends, resulting in a closer distance between the resolver and the motor rotor compared to the distance between the resolver and the coil ends. Given this situation, the shielding structure disclosed in Patent Document 1, which involves placing a shielding plate between the resolver stator core and the coil ends, is insufficient to shield electromagnetic noise generated from the rotor or the air gap between the rotor and stator. Furthermore, the shielding plate needs to be properly maintained in order to function as a shielding element for the resolver.

[0006] This specification discloses a motor unit comprising a motor and a rotary transformer for detecting the rotation angle of the motor. The motor comprises: a stator having a stator core and coils mounted on the stator core; and a rotor disposed further inward than the inner circumferential surface of the stator core and rotatably supported. The rotary transformer comprises: a rotary transformer rotor mounted on a rotor shaft serving as the shaft of the rotor and capable of rotating with the rotor shaft; and a rotary transformer stator having a rotary transformer stator core formed in an annular shape and disposed to surround the outer circumferential surface of the rotary transformer rotor, and rotary transformer coils mounted on the rotary transformer stator core. The motor unit further comprises: a shielding plate made of a magnetic material disposed between the rotor and the rotary transformer stator; and an intermediate component made of a non-magnetic material, situated between the shielding plate and the rotary transformer stator to hold the shielding plate at a predetermined distance separated from the rotary transformer stator.

[0007] According to the structure, electromagnetic noise generated from the rotor or the air gap between the rotor and the stator can be shielded by a shielding plate that is positioned between the rotor and the stator by maintaining a specified distance between the intermediate component and the stator of the rotary transformer, thereby suppressing false detections caused by the rotary transformer. Attached Figure Description

[0008] Figure 1 It is a cross-sectional view that simply represents the structure of the motor unit.

[0009] Figure 2 It is an exploded perspective view showing a portion of the shielding plate, the stator of the rotary transformer, and the housing.

[0010] Figure 3 This is a partial sectional view showing an example of the shielding plate and the stator of the rotary transformer being fixed to the housing by fastening components.

[0011] 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.

[0012] Figure 5 It means and Figure 2 Three-dimensional views of the shielding plates involved in different examples.

[0013] Figure 6 This is a diagram used to illustrate the effects of this embodiment. Detailed Implementation

[0014] The main features of the embodiments described below are listed below. These features can be combined arbitrarily.

[0015] According to the motor unit disclosed in this specification, the shielding plate and the intermediate component can be configured as a pre-formed covering material that is joined together with each other.

[0016] According to the structure, by using a covering material throughout the entire range between the shielding plate and the stator of the rotary transformer, the shielding plate can be easily and reliably held at a position separated from the stator of the rotary transformer at a specified distance.

[0017] According to the motor unit disclosed in this specification, the shielding plate, the intermediate component, and the rotary transformer stator can be fixed to the housing containing the motor by a common fastening component.

[0018] According to the structure described, the shielding plate can be positioned relative to the stator of the rotary transformer via an intermediate component using a simple structure.

[0019] According to the motor unit disclosed in this specification, the intermediate component may be configured as a washer through which the fastening component is inserted.

[0020] According to the structure described, the shield can be held at a specified distance from the stator of the rotary transformer at a lower cost by using washers.

[0021] According to the motor unit disclosed in this specification, the shielding plate may be configured to cover the entire area of ​​the stator of the rotary transformer opposite to the rotor.

[0022] 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.

[0023] 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.

[0024] Figure 1 The structure of a motor unit 10, which includes a motor 20 and a rotary transformer 30 for detecting the rotation angle of the motor 20, is simply shown using a cross-section through the central axis Ax of the motor 20. The motor unit 10 is housed within a housing 11. However, a portion of the structure of the motor unit 10 may exist outside the housing 11. The motor 20 is driven by receiving power from an external source. The concept of a motor includes various types of motors such as DC (direct current) motors, AC (alternating current) motors, stepper motors, and servo motors.

[0025] The motor 20 includes a stator 21 and a rotor 24. The stator 21 includes a cylindrical stator core 22 fixed within the housing 11 and coils 23 mounted on the stator core 22. Hereinafter, the radial direction, circumferential direction, and axial direction of the 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 the central axis Ax and extends radially from the central axis Ax. In the radial direction, the side closer to the central axis Ax is the radial inner side, and the side farther from the central axis Ax is the radial outer side. In this embodiment, the cylindrical or annular shape includes not only the case where the shape in the cross section perpendicular to the axial direction is circular, but also the case where the shape is close to a polygon.

[0026] 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 1In 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.

[0027] The rotor 24 is positioned radially inward from the inner circumferential surface of the stator core 22 and is rotatably supported. The rotor 24 is rotatably supported about a central axis Ax, for example, by a bearing (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).

[0028] 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.

[0029] 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.

[0030] The motor unit 10 includes a shielding plate 40 made of a magnetic material, which is positioned between the rotor 24 and the rotary transformer stator 32 at a predetermined distance from the stator 32. The magnetic material is, for example, iron. Other examples include nickel or cobalt. The shielding plate 40 is configured not to contact the rotary transformer stator 32. Figure 1The 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 air gap between the rotor 24 and the stator 21 is shielded by the shielding plate 40, 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 close due to the requirement for miniaturization of the motor unit 10.

[0031] 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.

[0032] according to Figure 1 The 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.

[0033] 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.

[0034] 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 2The 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.

[0035] In the above-described configuration where the shielding plate 40 does not contact the stator 32 of the rotary transformer, it can simply be fixed to 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 4 The bolts 50 penetrate axially. Furthermore, in the rotor counterplate 41 side, multiple holes 32a for inserting bolts 50 penetrate axially. Also, within the housing 11, a boss 12 for inserting and screwing the bolts 50 is erected axially. Therefore, a common bolt 50 is inserted from the rotor counterplate 41 side into the aligned holes 43a, holes 32a, and boss 12, and the bolt 50 is screwed relative to the boss 12, thereby fixing the shielding plate 40 and the rotor counterplate 32 to the housing 11.

[0036] 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 is magnetically disconnected from the rotary transformer stator 32, and the shielding plate 40 accurately shields electromagnetic noise generated from the rotor 24 or the air gap between the rotor 24 and the stator 21, suppressing false detections caused by the rotary transformer 30.

[0037] Figure 3 The image shows a simplified example, through a partial sectional view, of the shielding plate 40 and the rotary transformer stator 32 being fixed to the housing 11 by fastening components. 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 3In 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 , 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.

[0038] according to Figure 3 Hole 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, thereby fixing the shielding plate 40, intermediate component 60, and rotary transformer stator 32 to the housing 11. Thus, 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 external and internal threads, respectively.

[0039] Figure 4 In the partial sectional view, the shielding plate 40 and the rotary transformer stator 32 are simply shown to be fixed to the housing 11 by fastening components and in conjunction with... 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 aligned holes 43a, the annular washer (intermediate component 60), the hole 32a, and the boss 12, with the bolt 50 screwed relative to the boss 12, thereby fixing the shielding plate 40, the intermediate component 60, and the rotary transformer stator 32 to the housing 11. By using the washer, the shielding plate 40 can be held at a predetermined distance from the rotary transformer stator 32 at a lower cost.

[0040] A hole 43a is formed in the shielding plate 40. The hole 43a allows electromagnetic noise to pass through, thereby reducing the shielding effect based on the shielding plate 40. In this case, 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. Thus, the hole 43a is blocked by the head of the bolt 50, thereby maintaining the shielding effect based on the shielding plate 40.

[0041] In this embodiment of the invention, the structure may include a spacer or other component other than a non-magnetic intermediate component 60 to maintain the distance between the shielding plate 40 and the stator 32 of the rotary transformer. 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.

[0042] Figure 5 In the middle, 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 1-4 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.

[0043] 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 when the shielding plate 40 is absent in this embodiment, and the double-dotted line represents the error Y when the shielding plate 40 is present in this embodiment. Figure 6 In the diagram, the single-dotted line represents the error Y when the shielding plate 40 contacts 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 when there is no shielding plate 40. According to... Figure 6 When the distance X is less than or equal to a predetermined value X1, the error Y without shielding plate 40 is greater than the error Y with shielding plate 40. Furthermore, the difference between the error Y without shielding plate 40 and the error Y with shielding plate 40 increases as the distance X (less than or equal to a predetermined value X1) decreases. Figure 6It can also be considered that this embodiment performs well when the distance between the rotary transformer 30 and the rotor 24 is close due to the requirement of miniaturization of the motor unit 10.

[0044] 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.

[0045] Symbol Explanation

[0046] 10-Motor unit, 11-Housing, 12-Boss, 20-Motor, 21-Stator, 22-Stator core, 23-Coil, 23a-Coil end, 24-Rotor, 25-Rotor shaft, 30-Resolver, 31-Resolver rotor, 32-Resolver stator, 33-Resolver stator core, 34-Resolver coil, 40-Shielding plate, 41-Rotor opposing plate, 42-Shielding side plate, 43a-Hole, 50-Bolt, 60-Intermediate component.

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 is positioned further inward than the inner circumferential surface of the stator core and is rotatably supported. The rotary transformer has the following features: A rotary transformer rotor, mounted on a rotor shaft that serves as the shaft of the rotor and capable of rotating with the rotor shaft; and A rotary transformer stator having a stator core formed in a ring shape and configured to surround the outer peripheral surface of a rotary transformer rotor, and rotary transformer coils mounted on the stator core. The motor unit also includes: A shielding plate, which is made of a magnetic body disposed between the rotor and the stator of the rotary transformer; and An intermediate component, which is located between the shielding plate and the stator of the rotary transformer to hold the shielding plate at a predetermined distance from the stator of the rotary transformer, and is made of a non-magnetic material.

2. The motor unit according to claim 1, characterized in that, The shielding plate and the intermediate component are pre-formed covering materials that are joined together.

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

4. The motor unit according to claim 3, characterized in that, The intermediate component is a washer through which the fastening component is inserted.

5. 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.

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