Angle sensor

Abstract

[Problem] To provide an angle sensor capable of fixing a stator stack while absorbing variation in thickness of the stator stack without impairing strength of a cover. [Solution] A resolver 1 comprises: a stator 100 that extends in the circumferential direction about the rotation axis direction; a rotor 30 that faces the stator 100 in the radial direction in which the distance to the center is measured; an insulator 120 that is mounted to the stator 100; a coil 126 wound on the insulator 120; a cover 50 that covers a part of the stator 100; and an O-ring 40. In the rotation axis direction, the O-ring 40 is sandwiched between the stator 100 and the cover 50.

Description

Angle Sensor

[0001] The present invention relates to an angle sensor such as a resolver, and more particularly to an improvement in the fixing structure of a stator.

[0002] Resolvers have been known as a means for detecting the rotation angle of rotating electrical machines such as motors and generators. A resolver is configured by fixing a stator to a case and placing a rotor inside the stator. The stator is configured by attaching an insulator to a stator stack and winding a conductor around it.

[0003] Since the stator stack is made by stacking plate-shaped stator cores and crimping them together, variations in thickness can occur. Therefore, a stator fixing structure that can accommodate variations in the thickness of the stator stack is desired. In the resolver disclosed in Patent Document 1, when fixing the detection stator 32 to the case 12, a ring-shaped locking member 51 presses the edge of the detection stator 32 against a part of the case 12, thereby fixing the detection stator 32 to the case 12.

[0004] Japanese Patent Application Laid-Open No. 2003-23761

[0005] The resolver in Patent Document 1 has a configuration in which a locking member 51 having a shape that matches the shape of the recess 40 is attached to a multi-stage recess 40, and flexible portions 58 between a plurality of notches 57 formed in a flat flange portion 54 press against the edge of the detection stator 32. This raises concerns that the strength of the flexible portions 58 may be reduced, resulting in a lack of reliability in fixing the detection stator 32. There has also been a demand for a cover such as the locking member 51 to have a function to prevent foreign matter such as oil and dust from entering.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an angle sensor that can fix the stator stack by absorbing variations in the thickness of the stator stack without compromising the strength of the cover, and that can also provide a function to prevent the cover from being contaminated with foreign matter.

[0007] The present invention is an angle sensor comprising a stator extending circumferentially around the direction of a rotation axis, a rotor facing the stator in a radial direction at a distance from the center, an insulating member attached to the stator, a conductor wound around the insulating member, a cover covering part of the stator, and an elastic body, wherein the elastic body is sandwiched between the stator and the cover in the direction of the rotation axis.

[0008] According to the present invention, the stator is pressed by the elastic body, so that the stator can be fixed while absorbing variations in the thickness of the stator stack.

[0009] 1 is an exploded perspective view showing a resolver according to an embodiment of the present invention; FIG. 2 is a perspective view of a resolver according to an embodiment; FIG. 3 is a perspective view of a resolver according to an embodiment with a terminal pin cover removed, and FIG. 4 is an enlarged view of a portion indicated by arrow B in FIG. 4A; FIG. 5 is a cross-sectional view of a resolver according to an embodiment, and FIG. 6 is an enlarged view of a portion indicated by arrow B in FIG. 5A; FIG. 6 is a plan view of a housing according to an embodiment; FIG. 7 is a perspective view of a housing according to an embodiment; FIG. 7 is a rear view of a cover according to an embodiment; and FIG. 8 is a perspective view of a cover according to an embodiment as viewed from the rear side.

[0010] 1. Overall Configuration of Resolver Fig. 1 shows a resolver (angle sensor) 1 according to an embodiment of the present invention. The resolver 1 is a VR (variable reluctance) resolver. The resolver 1 includes a housing 200. A stator 100 is fixed to the housing 200, and a rotor 30 is disposed inside the stator 100. A cover 50 is attached to the stator 100 via an O-ring 40. Each component will be described in detail below.

[0011] The rotor 30 is fixed to the output shaft of a motor (not shown) whose angle is to be detected. The motor is located to the left or right of the resolver 1 in FIG. 1 . When viewed from the axial direction, the rotor 30 has a shape with multiple protrusions 31 that protrude radially outward and are arranged in the circumferential direction. The rotor 30 has a structure in which multiple thin-plate rotor cores are stacked in the axial direction. In the description herein, the direction of the output shaft is referred to as the "axial direction," the direction perpendicular to the axial direction is referred to as the "radial direction," and the direction of rotation around the output shaft is referred to as the "circumferential direction." The axial direction coincides with the extension direction of the rotation shaft of the rotor 30 (rotation shaft direction). The terms "up" and "down" refer to the up and down directions in FIG. 3 .

[0012] The thin rotor core that constitutes the rotor 30 is manufactured by pressing electromagnetic steel sheets made of soft magnetic material, amorphous material, or the like into the shape shown in the figure. Multiple rotor cores are stacked in the axial direction and fixed by caulking to form the rotor 30, but the rotor 30 may also be formed from a single rotor core.

[0013] The stator 100 extends in the circumferential direction around the rotation axis of the output shaft and is disposed radially outside the rotor 30. A gap serving as an air gap (magnetic gap) is provided between the rotor 30 and the stator 100, allowing the rotor 30 to rotate inside the stator 100, and the stator 100 and the rotor 30 form a magnetic circuit.

[0014] As shown in FIG. 1 , the stator 100 has a stator stack 110. The stator stack 110 has a structure in which multiple thin plate-shaped cores are stacked in the axial direction. The thin plate-shaped core includes an annular core back 111 and multiple teeth 112 that protrude radially inward from the core back 111 and are arranged in the circumferential direction. The core is manufactured by pressing electromagnetic steel sheets made of soft magnetic material, amorphous material, or the like. Multiple such cores are stacked in the axial direction and fixed by crimping to obtain the stator stack 110. Multiple (five in this example) grooves 113 extending in the axial direction are formed on the outer periphery of the stator stack 110.

[0015] Insulators (insulating members) 120 are fixed to both axial sides of the stator stack 110. The insulators 120 are made of insulating resin and molded separately from the stator stack 110. The insulators 120 are composed of an upper insulator 121 and a lower insulator 122. The lower insulator 122 is integrally formed with a terminal block 123 that protrudes radially outward. As shown in FIGS. 1 and 4 , the upper insulator 121 and the lower insulator 122 each include a winding portion 124 fixed to each tooth 112 and a flange portion 125 that protrudes axially from the radially inner end of the winding portion 124. The upper insulator 121 also includes a ring (annular wall) 128 that connects the radially outer ends of the winding portions 124. A conductor is wound around the winding portion 124 to form a coil 126. In addition to the above example, the insulator 120 may be injection molded using the stator stack 110 as an insert material.

[0016] A plurality of terminal connection pins 127 (six in this example) are integrally molded into the terminal block 123 by insert molding. Each terminal connection pin 127 is crank-shaped, with one end 127a protruding upward (to the left in FIG. 1) and the other end 127b protruding downward from the terminal block 123 (see FIG. 4). One end 127a of each terminal connection pin 127 is slightly inclined radially outward. A conductor wire drawn from the coil 126 is wound around the other end 127b of each terminal connection pin 127, and the conductor wire and the connection pin are electrically fixed by welding or soldering.

[0017] Housing 200 has a generally circular shape in plan view and includes a generally circular tube 220. An annular protrusion 250 that protrudes axially upward is formed in the center of tube 220. Stator stack 110 is fixed to the inside of annular protrusion 250. As shown in FIG. 4B , a step 251 (the surface at the other end) that is smaller in diameter than the rest of the inner periphery of annular protrusion 250 is formed at the lower end of the inner periphery of annular protrusion 250, and the lower edge of stator stack 110 is positioned and fixed by abutting step 251.

[0018] As shown in Figure 5, multiple (five in this example) recesses 252 that are recessed radially inward are formed on the outer periphery of the annular protrusion 250, and as shown in Figure 4 (B), a protrusion (engaged portion) 252b that protrudes radially outward via an inclined surface 252a is formed at the lower end of the recess 252.

[0019] 5 and 6, a plurality of (four in this example) ridges 253 that protrude radially inward and extend axially are formed on the inner periphery of the annular protrusion 250. The ridges 253 fit into grooves 113 (see FIG. 1) formed on the outer periphery of the stator stack 110, and function to position the stator stack 110 and prevent it from rotating.

[0020] 4(B), the upper end surface (the surface at one end) of the annular protrusion 250 is positioned at approximately the same position as the upper end surface of the stator stack 110, and a plurality of (four in this example) annular protrusions (annular walls) 254 are formed on its radially outer edge, protruding axially upward and extending circumferentially. In the axial direction, the upper end surface (the surface at one end) of the annular protrusion 250 faces the O-ring 40 adjacent to the stator stack 110. In addition, the upper end surface of the annular protrusion 250 faces the flange 51 of the cover 50 in the axial direction, with the O-ring 40 interposed therebetween.

[0021] As shown in Fig. 4A, a protrusion 260 that is circular in plan view and protrudes axially upward is formed in the center of the housing 200. Also, as shown in Fig. 1, a terminal block accommodating portion 270 is formed on the upper end surface of the tube 220. The terminal block accommodating portion 270 includes side walls 271 that surround both sides of the terminal block 123. A guide 273 extending radially is formed on the side wall 271. As shown in Fig. 3B, a rounded chamfer 273a is formed at the radially outer corner of the guide 273.

[0022] 1 and 2 show the terminal pin cover 280. The terminal pin cover 280 is box-shaped with an open bottom and radially inner surface, and grooves 281 along which the guides 273 slide are formed on both side surfaces.

[0023] As shown in Figure 6, a block 240 is formed on the outer periphery of the tube 220, protruding radially outward and axially downward. One end of a terminal pin 243 protrudes radially outward from the terminal block accommodating portion 270, and the other end of the terminal pin 243 protrudes from the back surface of the block 240. The terminal pin 243 is molded integrally with the tube 220 and the block 240 by insert molding. The other end of the terminal pin 243 is connected by appropriate means to a lead wire connected to an external power source.

[0024] As shown in FIG. 3B, by fixing the stator 100 to the housing 200, the terminal connection pins 127 of the terminal block 123 come into contact with the terminal pins 243, and the two are electrically fixed to each other at this point by welding or soldering.

[0025] Next, the cover 50 will be described with reference to Figures 7 and 8. The cover 50 comprises a flange (a radially extending portion) 51 having a circular opening 51a in its center, and a side wall (cylinder) 52 extending axially from the peripheral edge of the flange 51. The side wall 52 has a plurality of slits 53 formed therein, and elastically deformable legs 54 are formed between adjacent slits 53. The tips of the legs 54 have claws 54a that protrude radially inward. An opening 55 is also formed on one side of the side wall 52 to avoid contact with the terminal block 123. As shown in Figure 4(B) , the claws (engagement portions) 54a engage with protrusions 252b formed on the annular protrusion 250.

[0026] 4B , the O-ring 40, which serves as an elastic body, is sandwiched and fixed in a compressed and elastically deformed state between the flange 51 of the cover 50 and the stator stack 110. As a result, the stator stack 110 is pressed against the step 251 of the annular protrusion 250.

[0027] The material of the O-ring 40 can be selected from any of a variety of materials, including natural rubber and synthetic rubbers such as BR (butadiene rubber), SBR (styrene butadiene rubber), and IIR (butyl rubber). Among these, NBR (nitrile rubber) and urethane rubber are desirable due to their excellent oil resistance. The elastic body is not limited to the O-ring 40, but may also be a packing or gasket with a rectangular cross section. It may also be an elastic body with a C-shaped cross section that is partially open.

[0028] 2. Resolver assembly method i) Mounting the stator 100 to the housing 200 The ridge 253 of the annular protrusion 250 of the housing 200 is inserted into the groove 113 of the stator stack 110, and the stator 100 is moved toward the housing 200 until the edge of the stator stack 110 abuts against the step 251 of the annular protrusion 250. This causes the tip of the terminal pin 243 provided on the housing 200 to abut against one end 127a of the terminal connection pin 127 provided on the terminal block 123. Because one end 127a of the terminal connection pin 127 is slightly inclined radially outward, the one end 127a is elastically or plastically deformed radially inward by the terminal pin 243, and the two come into close contact.

[0029] ii) Mounting the cover 50 on the housing 200 The O-ring 40 is inserted between the ring 128 of the upper insulator 121 and the annular protrusion 254 of the annular protrusion 250. The inner diameter of the O-ring 40 is equal to or slightly larger than the outer diameter of the ring 128, so the O-ring 40 is placed on the edge of the stator stack 110 with the inner periphery of the O-ring 40 in contact with the outer periphery of the ring 128 or with a partial gap between them.

[0030] Next, the legs 54 of the cover 50 are inserted into the recesses 252 of the annular protrusion 250 of the housing 200. When the cover 50 is then moved toward the housing 200, the claws 54a at the tips of the legs 54 ride up onto the inclined surfaces 252a of the recesses 252 and pass over the protrusions 252b, thereby engaging the two. In this state, the O-ring 40 is compressed by the edge of the stator stack 110 and the flange 51 of the cover 50, and the elastic force of the O-ring 40 presses the stator stack 110 against the step 251 of the annular protrusion 250. Thereafter, one end 127a of the terminal connection pin 127 and the terminal pin 243 are fixed to each other by welding or soldering.

[0031] Next, the terminal pin cover 280 is attached to the terminal block accommodating portion 270. In this case, the guides 273 of the terminal block accommodating portion 270 are inserted into the grooves 281 of the terminal pin cover 280, and the terminal pin cover 280 is brought into contact with the upper end surface of the cylinder 220 of the housing 200. As a result, the terminal pins 243 and the terminal connection pins 127 are covered by the terminal pin cover 280, as shown in FIG.

[0032] In the resolver 1 configured as described above, the O-ring 40 is sandwiched between the stator stack 110 and the cover 50, so the stator stack 110 is pressed against the step 251 of the annular protrusion 250 of the housing 200. Therefore, even if there is variation in the height of the stator stack 110, the variation is absorbed by the elasticity of the O-ring 40, allowing the stator stack 110 to be firmly fixed. The O-ring 40 also functions as a buffer against external stress, thereby protecting the resolver 1.

[0033] In particular, in the above embodiment, the O-ring 40 is biased toward the stator stack 110 by the cover 50, so that the fixation of the stator stack 110 is completed at the same time as the cover 50 is attached to the annular protrusion 250 of the housing 200, resulting in excellent workability.

[0034] Furthermore, in the above embodiment, the stator stack 110 is sandwiched between the step portion 251 of the annular projection 250 and the O-ring 40, so that the stator stack 110 can be firmly fixed.

[0035] In the above embodiment, the ring (annular wall) 128 of the insulator 120 faces the annular protrusion (annular wall) 254 of the annular protrusion 250 in the radial direction via the O-ring 40. In this structure, the O-ring 40 is disposed between the ring 128 of the insulator 120 and the annular protrusion 254 of the annular protrusion 250, which provides excellent workability when disposing the O-ring 40.

[0036] Furthermore, since the position of the upper end surface of the stator stack 110 and the position of the annular protrusion 250 are the same, the deformation of the O-ring 40 can be maintained normal when the O-ring 40 is compressed by the cover 50, and the biasing force of the elastic body can be balanced evenly.

[0037] Furthermore, the cover 50 can be attached to the annular protrusion 250 by snap-fitting the claws 54a of the cover 50 and the protrusions 252b of the annular protrusion 250, which provides excellent workability.

[0038] 3. Modifications The present invention is not limited to the above embodiment, and various modifications are possible, as follows. i) Although the flange 51 of the cover 50 extends to the teeth 112 of the stator stack 110, it can be extended to the coil 126. In other words, the flange 51 and the coil 126 can be opposed to each other in the axial direction. This makes it possible to prevent foreign matter from entering the area around the coil 126.

[0039] ii) In the above embodiment, the other end of the terminal pin 243 is configured to be connected to a lead wire connected to an external power source, but, for example, a connector housing may be formed in the housing 200, and the other end of the terminal pin 243 may be made to protrude inside the connector housing.

[0040] The present invention can be used in an angle sensor that detects the rotation angle of a rotating electrical machine such as a motor or a generator.

[0041] 1... resolver (angle sensor), 30... rotor, 40... O-ring (elastic body), 50... cover, 51... flange (radially extending portion), 51a... opening, 52... side wall (cylinder), 53... slit, 54... leg portion, 54a... claw portion (engagement portion), 55... opening, 100... stator, 110... stator stack, 111... core back, 112... teeth, 113... groove, 120... insulator (insulating member), 121... upper insulator, 122... lower insulator, 123... terminal block, 124... winding portion, 125... flange portion, 126...coil, 127...terminal connection pin, 128...ring (annular wall), 127a...one end, 127b...other end, 200...housing, 220...cylinder, 240...block, 243...terminal pin, 250...annular protrusion, 251...step portion (surface of the other end), 252...recess, 252a...inclined surface, 252b...protrusion (engaged portion), 253...ridge, 254...annular protrusion (annular wall), 260...protrusion, 270...terminal block accommodating portion, 271...side wall, 273...guide, 273a...R chamfer, 280...terminal pin cover, 281...groove.

Claims

1. An angle sensor comprising: a stator extending in a circumferential direction centered on the direction of a rotation axis; a rotor facing the stator in a radial direction at a distance from the center; an insulating member fixed to the stator; a conducting wire wound around the insulating member; a cover covering a portion of the stator; and an elastic body, wherein the elastic body is sandwiched between the stator and the cover in the direction of the rotation axis.

2. The angle sensor according to claim 1, wherein the elastic body is biased toward the stator by the cover.

3. An angle sensor as described in claim 1 or 2, comprising a housing that accommodates the stator, the housing having one end and the other end in the direction of the rotation axis, the face of the other end of the housing and the stator being in contact in the direction of the rotation axis, and the face of the one end of the housing being adjacent to the stator and facing the elastic body in the direction of the rotation axis.

4. The angle sensor according to claim 3, wherein a surface of the one end of the housing faces the cover via the elastic body in the direction of the rotation axis.

5. An angle sensor according to claim 1 or 2, wherein the insulating member has an annular wall, the housing has an annular wall surrounding the annular wall of the insulating member, and the annular wall of the insulating member faces the annular wall of the housing in the radial direction via the elastic body.

6. The angle sensor according to claim 3, wherein the cover comprises a radially extending portion and a tube surrounding the radially extending portion, and the radially extending portion is in contact with the elastic body in the direction of the rotation axis.

7. The angle sensor according to claim 6, wherein the radially extending portion faces the conducting wire in the direction of the rotation axis.

8. The angle sensor according to claim 6 or 7, wherein the cylinder has an engaging portion extending in the radial direction, and the housing has an engaged portion that engages with the engaging portion.

Images