Electromagnetic shielding structure of resolver

Abstract

To achieve both noise shielding performance for reducing magnetic field noise and electric field noise and miniaturization of a shielding structure by verifying influence of the electric field noise in particular in a resolver and efficiently shielding the electric field noise.SOLUTION: An electromagnetic shielding structure of a resolver that detects a rotation angle of a motor includes a resolver stator having a resolver stator core formed by stacking a plurality of electromagnetic steel sheets and a resolver stator coil wound around the resolver stator core, and a coil portion shielding member having an electric field shielding effect and disposed in an axis-side space where the resolver stator faces a motor rotor of the motor in a rotation axis direction of the motor so as to cover the resolver stator coil.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic shielding structure for a resolver. [Background technology]

[0002] Resolvers are often used as sensors for detecting the rotation speed of drive or power-generating motors or generators (hereinafter simply referred to as "motors") mounted on vehicles such as electric vehicles and hybrid vehicles. Due to space constraints, resolvers are sometimes disposed inside (on the inner periphery of) the coil ends of the motor's stator. In such cases, electromagnetic noise generated at the coil ends can reduce the resolver's detection accuracy. To prevent this reduction in detection accuracy, a technology has become known in which an electromagnetic shielding member (electromagnetic shield) is provided to block electromagnetic noise, mainly in the space between the coil ends and the resolver (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-217519 Summary of the Invention [Problem to be solved by the invention]

[0004] To shield electromagnetic noise, it is best to install electromagnetic shielding materials in as many places as possible, but this leads to an increase in the overall size of the motor incorporating the resolver. On the other hand, reducing the number of electromagnetic shielding materials increases the electromagnetic noise. In other words, it has been difficult to achieve both noise shielding performance that reduces magnetic field noise and electric field noise and a compact shielding structure.

[0005] The present invention has been made to solve these problems, and examines the effects of electric field noise in particular on resolvers, and aims to achieve both noise shielding performance that reduces magnetic field noise and electric field noise by efficiently shielding electric field noise, and a compact shielding structure. [Means for solving the problem]

[0006] In a specific aspect of the present invention, an electromagnetic shielding structure for a resolver that detects the rotation angle of a motor includes a resolver stator having a resolver stator core formed by stacking multiple electromagnetic steel plates and a resolver stator coil wound around the resolver stator core, and a coil portion shielding member having an electric field shielding effect that is arranged to cover the resolver stator coil in the axial space where the resolver stator faces the motor rotor of the motor in the direction of the rotation axis of the motor. [Effects of the Invention]

[0007] According to the present invention, it is possible to achieve both noise shielding performance for reducing magnetic field noise and electric field noise by efficiently shielding electric field noise, and miniaturization of the shielding structure. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a part of a drive unit of an automobile including a motor to which an electromagnetic shielding structure according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the configuration of the periphery of a resolver. [Figure 3] FIG. 2 is a vertical cross-sectional view schematically showing the configuration of a resolver and its surroundings. [Figure 4] FIG. 10 is a cross-sectional view schematically showing the configuration around a resolver that employs an electromagnetic shielding member according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential means for solving the problems. In each drawing, components with the same reference numerals have the same or similar configurations. Furthermore, even in different examples, to avoid complication, components that are the same or similar to those already described may not be referenced by reference numerals.

[0010] 1 is a schematic diagram showing a portion of a drive unit of an automobile, including a motor 200 to which an electromagnetic shielding structure according to this embodiment is applied. The motor 200 is a power source for the drive unit that drives the automobile, and includes a motor stator 203 fixed to a case (not shown), and a motor rotor 204 rotatably disposed on the inner diameter side of the motor stator 203. A coil is wound around the motor stator 203, and a coil end 205 is formed on the portion of the coil that protrudes from the axial direction of the motor stator 203 (the Z-axis direction in the figure). Furthermore, a motor rotating shaft 206, which serves as an output shaft, extends from the center of the motor rotor 204, and a drive gear 221 is fixed to the motor rotating shaft 206.

[0011] A driven gear 222 meshes with the drive gear 221, and this driven gear 222 is fixed to one end of a counter shaft 223, and a differential drive pinion gear 224 is fixed to the other end of the counter shaft 223. A differential ring gear 225 meshes with this differential drive pinion gear 224. The differential ring gear 225 constitutes a part of a differential device 226, and an output shaft 227 extends from the differential device 226 and is connected to wheels (not shown).

[0012] In such a drive unit, when motor rotating shaft 206 of motor 200 rotates, the rotational force is transmitted to the wheels via drive gear 221, driven gear 222, countershaft 223, differential drive pinion gear 224, differential ring gear 225, differential device 226, and output shaft 227. Because the rotation of motor rotating shaft 206 is transmitted directly to the wheels via each shaft and gear in this way, in order to control the rotation speed and torque of the wheels, it is necessary to control the rotation speed of motor rotating shaft 206 with high accuracy, and to do so, it is necessary to detect the rotation speed of motor rotating shaft 206 with high accuracy.

[0013] The resolver 100 according to this embodiment is disposed near the base end of the motor rotating shaft 206 and at a position surrounded by the coil end 205 of the motor stator 203. In order for the resolver 100 to detect the rotation of the motor rotating shaft 206 with high accuracy, in this embodiment, electromagnetic shielding members 110 are disposed in the space between the motor rotor 204 and the resolver 100, and in the space between the coil end 205 and the resolver 100.

[0014] In this embodiment, as shown by the coordinate axes in the drawing, the axial direction of the motor rotation shaft 206 is defined as the Z-axis direction, and the plane perpendicular to the Z-axis is defined as the XY plane. In Fig. 1, the up-down direction of the drawing is defined as the X-axis direction, and the depth direction is defined as the Y-axis direction. In the subsequent drawings, similar coordinate axes based on the state in which the motor 200 is disposed as in Fig. 1 are also included to indicate the orientation of the structure depicted in each drawing.

[0015] 2 is a cross-sectional view schematically showing the configuration around the resolver 100. Specifically, it is the area A surrounded by the dotted line in FIG. 1, and shows a cross section along the YZ plane passing through the center line of the motor rotation shaft 206.

[0016] The resolver 100 is mainly composed of a resolver rotor 101 and a resolver stator 102. The resolver rotor 101 is fitted onto and fixed to a motor rotary shaft 206, and rotates integrally with the motor rotary shaft 206. The resolver stator 102 is composed of a resolver stator core 103 and a resolver stator coil 104. The resolver stator core 103 is made up of multiple overlapping electromagnetic steel sheets of the same shape, and the resolver stator coil 104 is wound around a part of the resolver stator core 103. The resolver stator 102 is supported via a support member 121 on a base member 120 that fixes a case (not shown), and is disposed in a space surrounded by coil ends 205, the motor rotor 204, and the base member 120.

[0017] If no electromagnetic shielding member is installed when the resolver stator 102 is arranged in this manner, the electric field generated by the high-voltage potential difference between the coil end 205 and the resolver stator 102, and the magnetic field generated by the current flowing through the coil end 205, will superimpose a noise signal on the detection signal of the resolver stator coil 104. Therefore, it is desirable to install an electromagnetic shielding member that shields both the electric field and the magnetic field so that it surrounds the entire resolver 100 as tightly as possible, but this would result in an increase in the size of the entire motor. Therefore, in this embodiment, the distribution of the electric field and the magnetic field, which are factors that cause noise, are verified, and a shielding member with an electric field shielding effect and a shielding member with a magnetic field shielding effect are installed in effective positions, respectively.

[0018] Specifically, the inventors of the present application have found that noise caused by electric fields can be significantly reduced by installing a shielding member having an electric field shielding effect in the axial space where the resolver stator 102 faces the motor rotor 204 in the rotational axis direction (Z-axis direction) of the motor rotation shaft 206. In addition, they have found that noise caused by magnetic fields can be significantly reduced by installing a shielding member having a magnetic field shielding effect in the circumferential space where the resolver stator 102 faces the coil end 205 in the circumferential direction perpendicular to the rotational axis direction.

[0019] Therefore, in the shaft-side space, a coil section shielding member 111 having an electric field shielding effect is arranged so as to cover the resolver stator coil 104, and in the circumferential-side space, an outer periphery shielding member 112 having a magnetic field shielding effect is arranged so as to cover the outer periphery of the resolver stator 102. The coil section shielding member 111 is a non-magnetic conductor with a relative permeability of about 1, and is connected to the ground potential via a support member 121 that supports the coil section shielding member 111. With this configuration, most of the electric field that tries to flow into the resolver stator coil 104 can be released to the ground potential.

[0020] Furthermore, the outer peripheral shielding member 112 is made of a magnetic material with a relative magnetic permeability of 1000 or more, and is arranged to have a gap between it and the resolver stator core 103. With this configuration, it is possible to block most of the magnetic field that attempts to flow into the resolver stator coil 104. Note that it is preferable that the outer peripheral shielding member 112 extends in the positive direction of the X-axis beyond the end of the opposing coil end 205 on the positive side of the X-axis. As described above, the electromagnetic shielding structure according to this embodiment has succeeded in achieving both noise shielding performance and a compact shielding structure by limiting the arrangement of shielding members with a high electric field shielding effect in locations that are highly affected by electric fields, and shielding members with a high magnetic field shielding effect in locations that are highly affected by magnetic fields, in accordance with the required specifications.

[0021] 3 is a vertical cross-sectional view schematically showing the configuration around the resolver 100. Specifically, it shows a cross section BB indicated by the dashed dotted line in FIG. 2, and the main elements hidden by the coil part shielding member 111 are indicated by dotted lines.

[0022] The resolver stator 102 is connected to wiring 122 that transmits a detection signal of the resolver stator coil 104 to the outside, and the wiring 122 is further connected to a connector 123 for connection to an external signal processing device. As described above, the coil section shielding member 111 is formed in an annular shape so as to cover the resolver stator coil 104, but may be configured to have an extension portion at its periphery that is made up of a wiring shielding portion 111a that covers the wiring 122 and a connector shielding portion 111b that covers the connector 123. With this configuration, it is possible to effectively shield an electric field that tends to flow into the wiring 122 and the connector 123. Note that since the wiring 122 and the connector 123 have various configurations, the extension portion may be formed to cover at least a portion of the wiring 122 and the connector 123 in accordance with the respective specifications.

[0023] Next, a modified example of the configuration of the electromagnetic shielding member will be described. Fig. 4 is a cross-sectional view that schematically shows the configuration around a resolver that employs an electromagnetic shielding member according to the modified example. Specifically, it is a cross-sectional view similar to the cross-sectional view of Fig. 2.

[0024] The electromagnetic shielding member according to the modified example differs from the above-described electromagnetic shielding member in the shape of the outer periphery shielding member 112. Specifically, the outer periphery shielding member 112 differs in that, in addition to an outer periphery portion 112a formed in a cylindrical shape so as to cover the outer periphery of the resolver stator 102, the outer periphery shielding member 112 has an extending portion 112b bent on the motor rotor 204 side and extending toward the motor rotating shaft 206. The extending portion 112b extends to a position in the shaft-side space so as not to cover the resolver stator coil 104, i.e., to a position where they do not overlap in the Z-axis direction. More preferably, the extending portion 112b faces the coil portion shielding member 111 and is positioned on the motor rotor 204 side. Since the outer periphery shielding member 112 has the extending portion 112b in this way, it is possible to effectively shield the magnetic field flowing from the motor rotor 204 side to the resolver stator 102. [Explanation of symbols]

[0025] 100... resolver, 101... resolver rotor, 102... resolver stator, 103... resolver stator core, 104... resolver stator coil, 110... electromagnetic shielding member, 111... coil portion shielding member, 111a... wiring shielding portion, 111b... connector shielding portion, 112... outer peripheral portion shielding member, 112a... outer peripheral portion, 112b... extension portion, 120... base member, 121... support member, 122... wiring, 123... connector, 200... motor, 203... motor stator, 204... motor rotor, 205... coil end, 206... motor rotating shaft, 221... drive gear, 222... driven gear, 223... counter shaft, 224... differential drive pinion gear, 225... differential ring gear, 226... differential device, 227... output shaft

Claims

1. An electromagnetic shielding structure for a resolver that detects the rotation angle of a motor, comprising: a resolver stator including a resolver stator core formed by stacking a plurality of electromagnetic steel plates and a resolver stator coil wound around the resolver stator core; a coil portion shielding member having an electric field shielding effect, which is disposed in an axial space where the resolver stator faces the motor rotor of the motor in the rotational axis direction of the motor so as to cover the resolver stator coil; An electromagnetic shielding structure for a resolver comprising:

2. 2. The resolver electromagnetic shielding structure according to claim 1, wherein the coil portion shielding member is made of a non-magnetic material and a conductor, and is connected to a ground potential.

3. 2. The electromagnetic shielding structure of a resolver according to claim 1, further comprising an outer circumferential shielding member having a magnetic field shielding effect, the outer circumferential shielding member being arranged to cover the outer circumferential portion of the resolver stator in a circumferential space where the resolver stator faces the coil ends of the motor in a circumferential direction perpendicular to the rotation axis direction.

4. 4. The resolver electromagnetic shielding structure according to claim 3, wherein the outer peripheral shielding member has an extension portion that is bent and extends to a position in the shaft-side space where it does not cover the resolver stator coil.

5. 5. The resolver electromagnetic shielding structure according to claim 4, wherein a portion of the extending portion faces the coil portion shielding member in the direction of the rotation axis, and the extending portion is positioned on the motor rotor side.

6. 2. The resolver electromagnetic shielding structure according to claim 1, wherein the coil section shielding member has an extension that covers at least a part of the wiring and connector connected to the resolver stator coil.

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