Rotary transformer

Abstract

There is provided a resolver including teeth, a stator core, and coils, a plurality of the teeth are arranged in a circumferential direction of the stator core and protrude in a radial direction of the stator core, the coils are mounted to each of the plurality of the teeth, and each of the plurality of the teeth protrudes in a radial direction of the stator core. The coil attached to at least one of the plurality of teeth is disposed at a position different from the coil attached to the other teeth in the radial direction of the stator core.

Description

[0001] Cross-reference of related applications This application is based on Japanese Patent Application No. 2024-168817, filed with the Japan Patent Office on September 27, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to rotary transformers. Background Technology

[0003] In the rotary transformer disclosed in Japanese Patent Application Publication No. 2012-239310, the excitation winding is wound from the front end protrusion of the teeth of the stator core toward the radially outer side of the stator core. That is, the excitation winding is wound on the front end protrusion side of the teeth. By doing so, the positional deviation of the excitation winding is reduced. In addition, the rotation angle can be detected with high precision. Summary of the Invention

[0004] However, in recent years, there has been a demand for high-resolution rotary transformers, for example, for use in motors for electric vehicles or construction machinery. Therefore, to achieve high-resolution rotary transformers, research has been conducted on increasing the number of teeth arranged circumferentially on the stator core and increasing the number of output coils mounted on the teeth. However, if the number of output coils increases, adjacent output coils in the circumferential direction may interfere with each other. To prevent interference between adjacent output coils, it is necessary to increase the spacing between adjacent output coils by increasing the diameter of the stator core. Therefore, the issue of increasing the size of rotary transformers has arisen.

[0005] Therefore, the purpose of this disclosure is to provide a small and high-resolution rotary transformer.

[0006] The rotary transformer of this embodiment includes teeth, a stator core, and coils. A plurality of the teeth are arranged circumferentially on the stator core and protrude radially on the stator core. The coils are mounted on each of the plurality of teeth. The coil mounted on at least one of the plurality of teeth is arranged radially on the stator core at a different position than the coils mounted on the other teeth.

[0007] According to this disclosure, a small and high-resolution rotary transformer can be provided. The rotary transformer of this embodiment includes teeth, a stator core, and coils. A plurality of the teeth are arranged circumferentially on the stator core and protrude radially on the stator core. The coils are mounted on each of the plurality of teeth. The coil mounted on at least one of the plurality of teeth is arranged radially on the stator core at a different position than the coils mounted on the other teeth. Attached Figure Description

[0008] Figure 1 This is a top view of the rotary transformer of this embodiment. Figure 2 This is a partial enlarged view of the stator before the installation of the output coil in this embodiment. Figure 3 This is a top schematic diagram of the output coil used in this embodiment. Figure 4 This is a partially enlarged view of the stator after the output coil is installed in this embodiment. Detailed Implementation In the following detailed description, numerous specific details are presented for illustrative purposes and to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments can be implemented without these specific details. In other instances, well-known structures and apparatuses are shown schematically for the purpose of simplifying the drawings.

[0009] Hereinafter, this embodiment will be described with reference to the accompanying drawings. Furthermore, in the description of the embodiment, for components having the same reference numerals as those already described, the description of those components will be omitted for ease of explanation. Also, for ease of explanation, there may be cases where the dimensions of the components shown in these drawings differ from the actual dimensions of the components.

[0010] Figure 1 This is a top view of the rotary transformer 100 according to this embodiment. The rotary transformer 100 is an external rotor type. The rotary transformer 100 includes a stator 10 with a generally ring shape and a rotor 20 with a generally ring shape. The rotor 20 is rotatably disposed on the outer periphery of the stator 10. The rotary transformer 100 detects the amount of rotation of the rotor 20 relative to the stator 10. The rotary transformer 100 is, for example, a sensor for detecting the amount of rotation of a rotating body such as a motor. For the sake of explanation, the rotary transformer 100 will be described as a sensor for detecting the amount of rotation of a motor relative to its housing.

[0011] The stator 10 has a generally annular stator core 10a and generally cuboid teeth T. The teeth T protrude from the stator core 10a radially outward. Furthermore, the teeth T are evenly spaced along the circumference of the stator core 10a. Figure 1 In the example, a rotary transformer coil C is installed on each of the teeth T. The teeth T are configured such that the distance from the rotation center O of the rotary transformer 100 to the front end of each tooth T is equal.

[0012] The rotor 20 is a component capable of rotating relative to the stator 10. Figure 1In the example, the rotor 20 is disposed on the outer periphery of the stator 10. The rotor 20 is, for example, fixed to a motor shaft that rotates by a motor that detects the object, or a component such as a gear mounted on the motor shaft. The rotor 20 is a generally annular component. The outer peripheral surface of the rotor 20 may also be circular in frontal view.

[0013] On the inner circumferential surface of the rotor 20, there are sequentially arranged protrusions and recesses 20a in the circumferential direction. These protrusions and recesses 20a cause the radial thickness (the dimension from the inner circumferential surface to the outer circumferential surface) of the rotor 20 to vary periodically. Figure 1 In the example, the radial thickness of rotor 20 varies periodically along the circumferential direction. That is, the gap G from the inner circumferential surface of rotor 20 to the front end of the tooth T of stator 10 varies in the circumferential direction. Therefore, when rotor 20 rotates relative to stator 10, the gap permeability between rotor 20 and stator 10 varies sinusoidally according to the rotation angle θ of rotor 20.

[0014] like Figure 3 As shown, the rotary transformer coil C includes an excitation coil Cin and an output coil Cout. An AC power supply (not shown) is connected to the excitation coil Cin. If an AC current flows through the excitation coil Cin, a magnetic flux M is generated from the tooth T on which the rotary transformer coil C is mounted. This magnetic flux M links with the output coil Cout.

[0015] This linked magnetic flux generates an electromotive force (resolver signal) in the output coil Cout corresponding to the rotation angle θ of the rotor 20. An RD converter (not shown) is connected to the output coil Cout. The RD converter detects the rotation angle of the motor based on this resolver signal.

[0016] exist Figure 1 In the example, 16 sets of protrusions and recesses 20a are provided on the inner circumferential surface of the rotor 20. Therefore, the shaft angle is 16X. When the rotor 20 rotates one revolution, 16 cycles of the motor's output signal are obtained. However, in this embodiment, the shaft angle is not limited to 16X.

[0017] Figure 2 This is a partially enlarged view of the stator 10 before the installation of the rotary transformer coil C in this embodiment. Figure 2 As shown, a first tooth T1 and a second tooth T2 are provided on the stator 10. The shapes of the first tooth T1 and the second tooth T2 are different from each other. A stepped portion S is provided on the first tooth T1. A stepped portion is not provided on the second tooth T2. The first tooth T1 and the second tooth T2 are alternately provided in the circumferential direction of the stator core 10a. In addition, the radial height of the first tooth T1 on the stator core 10a is approximately the same as the radial height of the second tooth T2. In the following description, the first tooth T1 and the second tooth T2 are sometimes referred to simply as tooth T without special distinction.

[0018] The stepped section S is used for radial positioning of the rotary transformer coil C in the stator core 10a. Figure 2 In the example, a stepped portion S is provided at the base end of the first tooth T1. The stepped portion S is a rectangular portion with a width wider than the first tooth T1. The stepped portion S performs the radial positioning of the rotary transformer coil C by suppressing the movement of the rotary transformer coil C towards the radially inward side of the stator core 10a beyond the upper surface F (the radially outer surface of the stator core 10a). The first tooth T1 and the second tooth T2 are alternately arranged circumferentially on the stator core 10a. Therefore, as... Figure 1 As shown, the distance d1 from the rotation center O of the rotary transformer 100 to the rotary transformer coil C1 is different from the distance d2 from the rotation center O to the rotary transformer coil C2 which is adjacent to the rotary transformer coil C1 in the circumferential direction of the stator core 10a. In addition, Figure 2 The example provided illustrates a step portion S that constitutes the rectangular section. However, the shape of the step portion S is not limited to this example.

[0019] Figure 3 This is a top schematic view of the rotary transformer coil C used in this embodiment. The rotary transformer coil C has an excitation coil Cin, an output coil Cout, and a pair of generally cuboid-shaped first cover L1 and second cover L2.

[0020] The excitation coil Cin has a coil frame B1 and a winding W1. The coil frame B1 has a core BO1 of approximately cuboid shape and a pair of first flanges FU1 and second flanges FL1 of approximately cuboid shape. The coil frame B1 extends along the central axis L0 of the rotary transformer coil C. The pair of first flanges FU1 and second flanges FL1 are arranged such that they are sandwiched between the core BO1 from the central axis L0. The winding W1 is wound around the core BO1 of the coil frame B1. The output coil Cout has the same structure as the excitation coil Cin. Therefore, the description of the output coil Cout is omitted.

[0021] The excitation coil Cin and the output coil Cout are clamped together from the central axis direction L0 by a pair of first covers L1 and second covers L2. An internal space V is provided within the excitation coil Cin, the output coil Cout, and the pair of first covers L1 and second covers L2. Through teeth T are inserted into the internal space V. Additionally, in... Figure 1 In this configuration, if a rotary transformer coil C is installed on each tooth T, then the first cover L1 is located on one of the radial outer and inner sides of the stator core 10a. At this time, the second cover L2 is located on the other of the radial outer and inner sides.

[0022] Here, the first cover L1, the second cover L2, the first flange FU1 and the second flange FL1 of the coil frame B1, and the first flange FU2 and the second flange FL2 of the coil frame B2... Figure 3 The transverse length of the paper is defined as D2 (hereinafter also referred to as the width D2 of the rotary transformer coil). Furthermore, the winding W1 wound on the core BO1 of the coil frame B1 and the winding W2 wound on the core BO2 of the coil frame B2... Figure 3 The transverse length of the paper is defined as D3 (hereinafter, also referred to as the winding width D3). Furthermore, the internal space V... Figure 3 The horizontal length of the paper is defined as D4 (hereinafter also referred to as the width of the internal space D4).

[0023] In addition, such as Figure 2 As shown, the circumferential length of the stator core 10a at the front end of the tooth T is defined as D0 (hereinafter also referred to as the tooth width D0). Furthermore, the circumferential length of the step portion S is defined as D1 (hereinafter also referred to as the step width D1).

[0024] In the excitation coil Cin, the winding W1 wound around the core BO1 is housed between the first flange FU1 and the second flange FL1 of the coil frame B1. Therefore, the width D2 of the output coil is greater than the width D3 of the winding (D2>D3). Furthermore, the width D3 of the winding is greater than the width D4 of the internal space (D3>D4). The same dimensional relationship holds true in the output coil Cout.

[0025] In addition, the width D4 of the interior space is set to be greater than Figure 2 The width D0 of the tooth shown is smaller than the width D1 of the step (D1>D4>D0). That is, the width D4 of the internal space is greater than the width D0 of the tooth T, therefore, the rotary transformer coil C can be mounted on the tooth T. Furthermore, the width D4 of the internal space is smaller than the width D1 of the step. Therefore, in the first tooth T1, the rotary transformer coil C is in contact with the upper surface F of the step S and is positioned radially.

[0026] also, Figure 2 The radial height of the stator core 10a of the second tooth T2 shown is defined as HT. Furthermore, the radial height of the stator core 10a of the stepped portion S is defined as HS. And the difference between the radial heights of the two, HT-HS, is set such that the difference is greater than... Figure 3 The height HC of the rotary transformer coil C is shown (HT-HS>HC). Therefore, the rotary transformer coil C can be mounted on the first tooth T1 without protruding from the front end of the first tooth T1 outwards in the radial direction.

[0027] Figure 4This is a partially enlarged view of the stator 10 after the rotary transformer coil C is installed in this embodiment. Figure 4 As shown, the rotary transformer coil C1 is mounted on the first tooth T1. Similarly, the rotary transformer coil C2 is mounted on the second tooth T2. Furthermore, the rotary transformer coil C1 is positioned radially in the stator core 10a in contact with the upper surface F of the stepped portion S of the first tooth T1. Additionally, the rotary transformer coils C1 and C2 have the same construction. Moreover, the winding specifications of the rotary transformer coils C1 and C2 are also substantially the same. Specifically, the dimensions, shape, number of turns, resistance, and inductance of the rotary transformer coils C1 and C2 are substantially the same. As a result, the rotary transformer coils C1 and C2 can share a common coil frame. This reduces the component cost of the rotary transformer coil C.

[0028] exist Figure 4 In this context, the outer circumferential surface of the front end face of tooth T is defined as G1. The boundary surface between the stator core 10a and tooth T is defined as G2. Furthermore, the region on the boundary surface G2 from the central axis Lo1 of the first tooth T1 to the central axis Lo2 of the second tooth T2 is defined as A1. The arc length of this region A1 is defined as R1. Additionally, the region on the circumferential surface of the upper surface F of the stepped portion S from the central axis Lo1 of the first tooth T1 to the central axis Lo2 of the second tooth T2 is defined as A2. The arc length of this region A2 is defined as R2.

[0029] Here, it is assumed that the first tooth T1 is different from that in this embodiment and does not have the stepped portion S. Therefore, the rotary transformer coil C1 is the same as the rotary transformer coil C2 and is installed in a manner that contacts the boundary surface G2 of the stator core 10a.

[0030] In this case, Figure 4 In the diagram, the right half of the rotary transformer coil C1 and the left half of the rotary transformer coil C2 are located in region A1. The sum of half the width D2 of rotary transformer coil C1 (D2 / 2) and half the width D2 of rotary transformer coil C2 (D2 / 2) is D2. Therefore, if this sum D2 is greater than the arc length R1 of region A1, the midpoints of the first tooth T1 and the second tooth T2 of rotary transformer coils C1 and C2 on the boundary surface G2 will interfere with each other. Therefore, to prevent interference between rotary transformer coils C1 and C2, it is necessary to increase the diameter of the stator core 10a so that the arc length R1 of region A1 is greater than the sum D2. This leads to the enlargement of the rotary transformer.

[0031] Therefore, in this embodiment, as Figure 4As shown, a stepped portion S having a width D1 narrower than the width D2 of the resolver coil C1 is provided on the first tooth T1. Thus, the radial positions of adjacent resolver coils C are different from each other. A detailed description will be given later.

[0032] As Figure 4 shown, the region A1 includes the right half of the stepped portion S and the left half of the resolver coil C2. The sum of the length D1 / 2 of the right half of the width D1 of the stepped portion S and the length D2 / 2 of the left half of the width D2 of the resolver coil C2 is D2 / 2 + D1 / 2. The width D1 of the stepped portion S is set such that this sum D2 / 2 + D1 / 2 is less than the arc length R1 (D2 / 2 + D1 / 2 < R1). Further, the width D1 of the stepped portion S is set such that the width D1 of the stepped portion S is less than the width D2 of the resolver coil C1 (D1 < D2). According to such dimensional relationships, in the region of the stator core 10a in the radial direction from the boundary surface G2 of the stator core 10a to the upper surface F of the stepped portion S, the resolver coil C1 and the resolver coil C2 do not interfere with each other.

[0033] In addition, the region A2 is located at a position radially outside the region A1 with respect to the stator core 10a, and thus, the arc length R2 is greater than the arc length R1. That is, by increasing the radial height HS of the stepped portion S, the arc length R2 can be increased. The region A2 includes the right half of the resolver coil C1 and the left half of the resolver coil C2. The sum of the length D2 / 2 of half of the width D2 of the resolver coil C1 and the length D2 / 2 of half of the width D2 of the resolver coil C2 is D2. The height HS of the stepped portion S is set such that this sum D2 is less than R2 (D2 < R2). Thus, in the region radially outside the upper surface F of the stepped portion S, the resolver coil C1 and the resolver coil C2 do not interfere with each other.

[0034] In addition, in Figure 4 the example shown, the region A2 includes the right half of the resolver coil C1 and the left half of the winding W2 of the resolver coil C2. The sum of the length D2 / 2 of half of the width D2 of the resolver coil C1 and the length D3 / 2 of the left half of the width D3 of the winding W2 of the resolver coil C2 is D2 / 2 + D3 / 2. The height HS of the stepped portion S may also be set such that this sum D2 / 2 + D3 / 2 is less than R2 (D2 / 2 + D3 / 2 < R2).

[0035] As in the above structure, by adjusting the width D1 and the height HS of the stepped portion S provided on the first tooth T1, it is possible to suppress the interference between adjacent resolver coils C without increasing the diameter of the stator core 10a.

[0036] Furthermore, in this embodiment, two adjacent rotary transformer coils C are arranged at different positions radially in the stator core 10a. However, the radial height HT of the two teeth T on which these rotary transformer coils C are mounted is the same. Therefore, even compared to the case where the radial positions of adjacent rotary transformer coils C are the same, the impact on the detection accuracy of the rotary transformer 100 is sufficiently small.

[0037] As described above, in the structure of the rotary transformer of this embodiment, by providing a stepped portion S on the tooth T of the stator 10, the rotary transformer coil C mounted on one of the adjacent teeth T is arranged radially in a different position in the stator core 10a than the rotary transformer coil C mounted on the other tooth T. By doing so, interference between adjacent rotary transformer coils C can be suppressed. As a result, miniaturization of the high-resolution rotary transformer 100 can be achieved.

[0038] The rotary transformer of this embodiment has been described above. However, the technical scope of this embodiment should not be limited to the described embodiments. The described embodiments are merely examples of this embodiment. Those skilled in the art will understand that various modifications can be made to the described embodiments within the scope disclosed in the claims. The technical scope of this embodiment should be determined based on the scope disclosed in the claims and its equivalents.

[0039] For example, in the above embodiment, the rotary transformer is configured such that the radial positions of the stator core 10a of the rotary transformer coil C are alternately different. However, the rotary transformer of this embodiment is not limited to this example. Two second teeth T2 may be arranged circumferentially around the stator core 10a, following one first tooth T1. In this case, every two teeth, the radial position of the rotary transformer coil C is offset radially outward from the stator core 10a. Thus, the rotary transformer can also be configured such that the radial positions of the stator core 10a of the rotary transformer coil C are periodically different. Furthermore, the rotary transformer can also be configured such that the radial positions of the stator core 10a of the rotary transformer coil C are randomly different. Additionally, the rotary transformer can also be configured such that the radial positions of at least one stator core 10a of the rotary transformer coil C are different from the radial positions of the stator core 10a of the other rotary transformer coils. With such a structure, compared to the case where the radial positions of all the stator core 10a of the rotary transformer coil C are the same, miniaturization of the rotary transformer 100 can be achieved.

[0040] Furthermore, in this embodiment, in Figure 3In the rotary transformer coil C shown, winding W1 is wound on coil bobbin B1, and winding W2 is wound on coil bobbin B2. However, windings W1 and W2 can also be directly wound on tooth T. Furthermore, in the case where the rotary transformer coil C is composed of windings W1 and W2 directly wound on tooth T, Figure 2 The tooth T shown can also have a generally T-shaped shape, so that the front end of the stator core 10a located on the radially outer side of the tooth T is widened in the circumferential direction.

[0041] Furthermore, in this embodiment, the stator cores 10a of two adjacent rotary transformer coils C are radially different. To further reduce the impact of this difference on the detection accuracy of the rotary transformer, the RD converter can also correct the output signal from the rotary transformer coils C based on the aforementioned difference.

[0042] Furthermore, the RD converter connected to the rotary transformer 100 of this embodiment can also perform signal processing on the output signal through amplitude variation or phase variation.

[0043] Furthermore, the rotary transformer 100 of the above-described embodiment is an external rotor type. However, the rotary transformer 100 of this embodiment may also be an internal rotor type. The detailed description has been given for illustrative and explanatory purposes. Many variations and modifications are possible in accordance with the teachings above. The detailed description is not without omissions or intended to limit the subject matter described herein. Although the subject matter has been described in words with particular structural features and / or methodological processes, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or processes described. Rather, the specific features and processes described are illustrated as examples of implementing the claims.

Claims

1. A rotary transformer, wherein, The rotary transformer includes teeth, a stator core, and coils. The plurality of teeth are arranged circumferentially on the stator core and protrude radially on the stator core. The coil is mounted on each of the plurality of teeth. The coil mounted on at least one of the plurality of teeth is arranged radially on the stator core at a different position than the coils mounted on the other teeth.

2. The rotary transformer according to claim 1, wherein, The plurality of teeth includes a first tooth having a stepped portion and a second tooth not having the stepped portion. The stepped portion is configured to position the coil radially on the stator core.

3. The rotary transformer according to claim 2, wherein, The first tooth and the second tooth are alternately arranged in the circumferential direction of the stator core.

4. The rotary transformer according to claim 1, wherein, The winding specifications of the coil installed in one of the plurality of teeth are approximately the same as the winding specifications of all the coils installed in the remaining teeth.

5. The rotary transformer according to any one of claims 1 to 4, wherein, The rotary transformer is an external rotor type.

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