Position detection device

Abstract

Position detection device comprising: a wave (2); a housing (3) supporting the shaft (2) rotatably about an axis of the shaft (2); a magnetic circuit unit (4) fixed to the shaft (2) and arranged to rotate together with the shaft (2); a sensor (5) mounted on the housing (3), the sensor (5) comprising: a sensor body (51); a magnetic detector (50) projecting from the sensor body (51) to the magnetic circuit unit (4); and at least one engagement projection (52, 521, 522, 523) extending from the sensor body (51) near the magnetic detector (50) and engaging an engagement hole (36) arranged on the housing (3), an anti-rotation hole (37) arranged on at least one of the sensor body (51) and the housing (3) at a position spaced from the engagement hole (36) of the housing (3); and an anti-rotation pin (53) arranged on another of the sensor body (51) and the housing (3), wherein the anti-rotation pin (53) engages in the anti-rotation hole (37) to prevent the housing (3) and the sensor body (51) from rotating relative to each other about the engagement hole (36), wherein at least a part of the at least one engagement projection (52, 521, 522, 523) is in contact with an inner wall of the engagement hole (36) on a straight line (L) connecting a center of the magnetic detector (50) and a center of the anti-rotation pin (53), the at least one engagement projection (52, 521, 522, 523) comprises more than three engagement projections arranged on a circumference centered on the magnetic detector (50); a predefined engagement projection (521) of the engagement projections (52, 521, 522, 523) is in contact with the inner wall of the engagement hole (36) on the straight line (L) connecting the center of the magnetic detector (50) and the center of the anti-rotation pin (53); and other engaging projections (522, 523) of the engaging projections (52, 521, 522, 523) are in contact with the inner wall of the engaging hole (36) at intervals of 120° or less in a circumferential direction from a starting point (P) where the predefined engaging projection (521) of the engaging projections is in contact with the inner wall of the engaging hole (36).

Description

TECHNICAL FIELDThe present disclosure relates to a position detection device.PRIOR ARTA conventional known type of position detecting devices detects a rotational position of a shaft included in an actuator provided for rotationally driving a valve or the like. A position detecting device described in JP 5 720 962 B2 includes a shaft rotatably supported by a housing, a magnetic circuit unit fixed to the shaft, and a magnetic detector fixed to the housing and detecting magnetic flux through the magnetic circuit unit. When the shaft rotates, the position of the magnetic detector changes with respect to the position of the magnetic circuit unit, and the density of a magnetic flux passing through a magnetic detection surface of the magnetic detector changes. The magnetic detector outputs a voltage signal corresponding to the density of the magnetic flux flowing through the magnetic detection surface. The position detecting device may detect a rotational position of the shaft using the output of the magnetic detector.Further, JP 2001-208 763 A discloses a sensor unit attachable to and detachable from a cover, wherein an insertion hole into which a cylindrical portion of the sensor unit can be freely inserted and a rotation inhibiting through hole that can be fitted to a sensor-side through hole provided in the sensor unit are formed in a part of the cover. Engaging protrusions are formed at two locations on the peripheral edge of the insertion hole. The protrusions are engaged with threaded parts provided on the outer circumferential surface of the cylindrical portion and released again when the portion is rotated in the insertion hole. The rotation of the sensor unit against the cover is prevented by inserting first and second lock pins into the sensor-side through hole and the rotation-inhibiting through hole.DE 10 2008 054 000 A1 discloses a device for self-adjustment and a method for arranging a pulse speed transmitter with respect to a rotor. The pulse speed transmitter has a cylindrical sensor head and an adapter to a measurement and supply cable. An elastic clamping sleeve, which radially encompasses the cylindrical sensor head, is arranged in a force-fit manner in a bore of a holder, wherein the clamping sleeve forms a press fit of the sensor head in the bore. The press fit allows rotation and axial displacement between the holder and the sensor head. The pulse speed transmitter has an active orientation-dependent cylindrical sensor head and the clamping sleeve or the pulse speed meter has a rotation prevention means with respect to the holder. The anti-rotation device allows an axial displacement of the sensor head in the clamping sleeve with respect to the rotor for self-adjustment while maintaining the radial alignment or orientation of the sensor head with respect to the rotor.DE 73 42 182 U discloses an electrical rotational speed transmitter for generating an electrical signal which indicates the angular speed between two mutually rotatable components, having a rotor which is arranged on the rotating component and is provided with recesses or teeth, and a rod-shaped stator which is held on the fixed component by such elastic expansion or clamping bodies and lies opposite only part of the rotor, wherein the stator can be adjusted to a minimum air gap during assembly and, in the case of relative displacements between the components, a displacement of the stator in the direction of the stator axis is possible in the sense of an enlargement of the air gap when a considerable frictional adhesion is overcome, wherein a tube or pin which can be inserted into a bore of the fixed component running approximately parallel to the axis of the stator is provided for the holding, wherein this tube or pin is connected to the stator by means of a connecting part and wherein clamping or expanding bodies are provided which permit a displacement of the pin or tube in the bore and / or a displacement of the connecting part between the stator and pin during relative movements of the component.JP 2013-003 064 A discloses a rotation sensor including an insulation substrate having resistance patterns and conductor patterns, a slider, and a rotation substrate that holds and rotatably supports the slider. In a two-output rotation sensor that outputs an output voltage corresponding to a rotation angle of the rotation substrate, the resistance patterns and the conductor patterns are formed on the insulation substrate along circular arcs of two concentric circles, and include a first resistance pattern formed on a one-side semicircle of the inner concentric circle, a second resistance pattern formed on a one-side semicircle of the outer concentric circle, a first conductor pattern formed on another-side semicircle of the inner concentric circle, and a second conductor pattern formed on another-side semicircle of the outer concentric circle. One end of the first resistor pattern is connected to a first input terminal, one end of the second resistor pattern is connected to a second input terminal, and another end of the first resistor pattern and another end of the second resistor pattern are connected to a ground terminal.Moreover, US 2015 / 0 075 936 A1 discloses a rotation transmission device comprising a two-way clutch which is selectively engaged and disengaged by an electromagnetic clutch. The two-way clutch includes a control bracket and a rotating bracket. The control bracket and the rotary bracket have flanges and rods formed on the outer peripheral portions of the respective flanges and arranged to alternate in the circumferential direction, pockets being formed between adjacent rods. Two rollers are accommodated in each pocket. When the control bracket and the rotary bracket are rotated relative to each other, the rollers are urged by the rods to the released position. On opposite surfaces of an outer ring and of a control retaining element, a rotation prevention is provided. The anti-rotation feature is configured to prevent the control mount from rotating relative to the outer ring while the rollers are engaged, and thereby prevent the rollers from moving to the neutral position.SUMMARYHowever, when the position of the magnetic detector fixed to the housing is shifted in the position detecting device described in JP 5 720 962 B2, the magnetic circuit unit and the magnetic detector may shift in position with each other. In such cases, the output of the magnetic detector may be impaired. There is therefore a need to prevent the housing and the magnetic detector in the position detecting device from being displaced in position with each other to improve the detection accuracy.The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a position detection device that enables improved detection accuracy.The above object is achieved by the subject matter of claim 1. Advantageous further developments of the invention are the subject of the dependent claims that follow.According to an illustrative aspect of the present disclosure, a position detection device includes a shaft, a housing, a magnetic circuit unit, a sensor, a rotation prevention hole, and a rotation prevention pin. The housing rotatably supports the shaft about an axis of the shaft. The magnetic circuit unit is fixed to the shaft and configured to rotate together with the shaft. The sensor is mounted on the housing, and the sensor includes: a sensor body; a magnetic detector protruding from the sensor body to the magnetic circuit unit; and at least one engagement protrusion extending from the sensor body near the magnetic detector and engaging an engagement hole disposed on the housing. The anti-rotation hole is disposed at one of the sensor body and the housing at a position spaced from the engagement hole of the housing. The anti-rotation pin is disposed on another one of the sensor body and the housing, the anti-rotation pin being engaged with the anti-rotation hole to prevent the housing and the sensor body from rotating relative to each other about the engagement hole. At least a part of the at least one engagement protrusion is in contact with an inner wall of the engagement hole on a straight line connecting a center of the magnetic detector and a center of the anti-rotation pin.In this way, the sensor is prevented from rotating around the engagement hole provided on the housing by the anti-rotation pin, and the sensor is prevented from moving in a direction of the straight line connecting the center of the magnetic detector and the center of the anti-rotation pin by the engagement protrusion. The magnetic detector of the sensor and the housing are thus prevented from moving into position with respect to each other. Since the magnetic circuit unit rotates with the shaft supported by the housing, the magnetic detector and the magnetic circuit unit are prevented from shifting in positions with each other. The position detecting device can thus accurately detect a rotation angle of the shaft.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a sectional view of a position detection device according to an embodiment of the present disclosure. FIG. 2 is a sectional view taken along the line II-II in FIG. 1. FIG. 3 is a view of a sensor viewed from the direction III in FIG. 1. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1. FIG. 5 is a view of the sensor viewed from the direction V in FIG. 1, excluding the housing. FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5. FIG. 7 is a graph of an output characteristic of the position detecting device.DESCRIPTION OF EMBODIMENTSAn embodiment of the present disclosure will be described below with reference to the drawings. A position detecting device according to the embodiment of the present disclosure is illustrated in FIGS. 1 to 7. A position detection device 1 detects a rotational position of a shaft 2 included in an actuator that rotationally drives, for example, a wastegate valve, a throttle valve, or the like in a vehicle.As illustrated in FIG. 1, the position detection device 1 includes the shaft 2, a housing 3, a magnetic circuit unit 4, and a sensor 5.The shaft 2 is coupled to a motor 6 or the like and rotatable about a rotation axis O. The housing 3 includes a first housing 31 and a second housing 32. the first and second housings 31 and 32 have shaft holes 33 and 34, respectively, through which the shaft passes. The shaft 2 passes through the shaft holes 33 and 34 and is rotatably supported by the housing 3. The shaft 2 is rotatable in a predetermined range limited in a circumferential direction.As shown in FIGS. 1 and 2, the magnetic circuit unit 4 includes a turntable 40 fixed to the shaft 2 and having a fan-like shape, a first yoke 41, a second yoke 42, a first magnet 43, and a second magnet 44 fixed to the turntable 40. The magnetic circuit unit 4 is thus fixed to the shaft 2 and rotates together with the shaft 2, and illustration of the housing 3 is omitted in FIG. 2.The first magnet 43 and the second magnet 44 are arranged in a rotational direction of the shaft 2 and spaced apart from each other. A magnetic field generated by the first magnet 43 and that generated by the second magnet 44 have the same strength.The first yoke 41 and the second yoke 42 face each other and extend parallel to each other in arc shapes extending around the rotation axis O of the shaft 2. The first yoke 41 and the second yoke 42 are each manufactured using a magnetic body.The first yoke 41 has one end coupled to an N pole of the first magnet 43 and another end coupled to an S pole of the second magnet 44. The second yoke 42 has one end coupled to an S pole of the first magnet 43 and another end coupled to an N pole of the second magnet 44. The first magnet 43, the second magnet 44, the first yoke 41, and the second yoke 42 thus form a magnetic circuit.A magnetic flux flowing through the magnetic circuit unit 4 includes a main flux flowing from the N pole of the first magnet 43 to the S pole of the second magnet 44 via the first yoke 41 and from the N pole of the second magnet 44 to the S pole of the first magnet 43 via the second yoke 42 as indicated by arrows indicated by a symbol A in FIG. 2. The magnetic flux flowing through the magnetic circuit unit 4 includes a leakage flux flowing between the first yoke 41 and the second yoke 42 as indicated by arrows marked with a symbol B. In FIG. 2, some of the arrows schematically representing the main magnetic flux are marked with the symbol A, and some of the arrows schematically representing the leakage flux are marked with the symbol B.A magnetic detector 50 included in the sensor 5 is disposed between the first yoke 41 and the second yoke 42. When the shaft 2 and the magnetic circuit unit 4 rotate together, the magnetic detector 50 moves relative to the magnetic circuit unit 4 on a path indicated by a dot-and-dash line C in FIG. 2.As shown in Figs. 1 and 3 to 6, the sensor 5 is manufactured by injection molding synthetic resin to integrally include the magnetic detector 50, a sensor body 51, an engaging protrusion 52, a anti-rotation pin 53 and a connector 54.FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1 ; an installation position of the sensor 5 on the housing 3 is indicated by a dot-dash line. FIG. 5 is a diagram showing only the sensor 5 and the shaft 2 except for the housing 3 and the magnetic circuit unit 4 as viewed in the direction V in FIG. 1 ; in FIG. 5, positions of an engagement hole 36 and a rotation preventing hole 37 disposed in the housing 3 are indicated with dot-dash lines.As illustrated in FIGS. 3 and 4, the sensor body 51 has a substantially arc shape extending around the rotation axis O of the shaft 2. The sensor body 51 has a plurality of holes 56 passing through an edge portion of the sensor body 51 in a thickness direction of the sensor body 51. The sensor body 51 is attached to the housing 3 using a screw 57 passing through one of the holes 56 provided in the edge portion and engaging a screw hole 38 provided in the housing 3. When the sensor body 51 is fixed to the housing 3, the magnetic detector 50 passes through the engagement hole 36 disposed in the housing 3, the engagement protrusion 52 engages the engagement hole 36, and the anti-rotation pin 53 engages the anti-rotation hole 37 disposed in the housing 3.As illustrated in FIGS. 1 and 6, the sensor body 51 has a recess portion 55 extending from the housing 3 side in the thickness direction of the sensor body 51. As shown in FIGS. 1 and 2, the magnetic detector 50 protrudes from the recessed portion 55 of the sensor body 51 toward the magnetic circuit unit 4. The magnetic detector 50 is interposed between the first yoke 41 and the second yoke 42 of the magnetic circuit unit 4. The magnetic detector 50 is manufactured by, for example, molding two Hall ICs together with the resin constituting the sensor body 51. The two Hall ICs have magnetic detection surfaces substantially parallel to a plane 58 (see FIGS. 2 and 5 ) perpendicular to a radial direction of the shaft 2 in which the first yoke 41 and the second yoke 42 face each other. The magnetic detector 50 outputs a voltage signal corresponding to a density of the magnetic flux passing through the magnetic detection surfaces of the Hall ICs.FIG. 7 is a graph of an output characteristic of the magnetic detector 50. when the shaft 2 rotates and the magnetic circuit unit 4 moves relative to the magnetic detector 50, the magnetic detector 50 outputs a voltage signal indicated by a solid line D. For example, a voltage signal output from the magnetic detector 50 increases as the magnetic detector 50 approaches the first magnet 43 and decreases as the magnetic detector 50 approaches the second magnet 44. The voltage signal has a point symmetry about a midpoint voltage Vx. The center voltage Vx is output from the magnetic detector 50 when the magnetic detector 50 is located at an intermediate position X 0 (see FIG. 2 ) between the first magnet 43 and the second magnet 44.Positional displacement of the magnetic detector 50 and the magnetic circuit unit 4 with respect to each other may affect an output signal from the magnetic detector 50 illustrated in FIG. 7.As illustrated in FIGS. 1, 4, and 5, the engagement protrusion 52 extends from the recess portion 55 disposed in the sensor body 51 around the magnetic detector 50 toward the magnetic circuit unit 4 and engages with the engagement hole 36 disposed in the housing 3. The engagement protrusion 52 is in contact with an inner wall of the engagement hole 36 at a plurality of locations on a circumference of a circle centered on the magnetic detector 50.In the present embodiment, the engagement protrusion 52 includes three engagement protrusions disposed on a periphery of a circle centered on the magnetic detector 50. In the following description, the three engagement protrusions of the engagement protrusions 52 may be referred to as a first engagement protrusion 521, a second engagement protrusion 522, and a third engagement protrusion 523, as needed.As illustrated in FIG. 5, at least a part of the engagement protrusion 52 is in contact with the inner wall of the engagement hole 36 on a straight line connecting a center of the magnetic detector 50 and a center of the anti-rotation pin 53. In the following description, the straight line connecting the center of the magnetic detector 50 and the center of the anti-rotation pin 53 is referred to as "straight line L".In FIG. 5, a location where the first engagement protrusion 521 is in contact with the inner wall of the engagement hole 36 on the straight line L is marked with a symbol P. The engagement protrusion 52 is in contact with the inner wall of the engagement hole 36 on the circumference of the circle centered on the magnetic detector 50, at intervals of 120° or less in a circumferential direction around the magnetic detector 50 from a starting point at the location of the contact marked with the symbol P. In FIG. 5, a location where the second engagement protrusion 522 is in contact with the inner wall of the engagement hole 36 is marked with a symbol Q, and a location where the third engagement protrusion 523 is in contact with the inner wall of the engagement hole 36 is marked with a symbol R. In the present embodiment, the angles θ 1, θ 2, and θ 3 formed by lines connecting the center of the magnetic detector 50 and the symbols P, Q, and R are 120°, respectively.The three engaging protrusions of the engaging protrusion 52 are arranged to be symmetrical with respect to a plane S that is perpendicular to the magnetic detection surfaces of the magnetic detector 50. Specifically, the first engagement protrusion 521 and the second engagement protrusion 522 are arranged to be symmetrical with respect to the plane S, and the third engagement protrusion 523 has planar symmetry with respect to a center of the third engagement protrusion 523.The anti-rotation hole 37 in the housing 3 is spaced from the engagement hole 36. The twist preventing hole 37 has an elongated hole shape whose longitudinal direction is parallel to the straight line L. The anti-rotation hole 37 has an inner wall 371 in a width direction that is orthogonal to the straight line L. The inner wall 371 is in contact with the anti-rotation pin 53.The anti-rotation pin 53 has a cylindrical shape and protrudes from the recess portion 55 of the sensor body 51. The anti-rotation pin 53 is disposed at a position corresponding to that of the anti-rotation hole 37. The anti-rotation pin 53 is engaged with the anti-rotation hole 37 to prevent the housing 3 and the sensor 5 from rotating relative to each other about the engagement hole 36.In FIG. 5, a relative rotational path of the center of the magnetic detector 50 with respect to the magnetic circuit unit 4 is marked with a dot-dash line C. In the present embodiment, the anti-rotation pin 53 is disposed on the relative rotational path of the center of the magnetic detector 50 with respect to the magnetic circuit unit 4. That is, the anti-rotation pin 53 is disposed at a position that allows a distance from the center of the anti-rotation pin 53 to the rotation axis O of the shaft 2 to be equal to or greater than a distance from the center of the magnetic detector 50 to the rotation axis O of the shaft 2. In addition, a straight line connecting the center of the magnetic detector 50 and the rotation axis O of the shaft 2 and a straight line connecting the center of the anti-rotation pin 53 and the rotation axis O of the shaft 2 form an angle of 90° or greater. In this way, a distance from the magnetic detector 50 to the anti-rotation pin 53 can be increased. The sensor 5 and the housing 3 can thus be prevented from being displaced relative to each other.The connector 54 is disposed on the sensor body 51 at a position on an opposite side of a plane T from the magnetic detector 50. The plane T is perpendicular to the straight line L and includes the center of the anti-rotation pin. That is, the anti-rotation pin 53 is disposed between the connector 54 and the magnetic detector 50. The anti-rotation pin 53 can prevent vibration transmitted from the connector 54 to the sensor body 51 from being transmitted to the magnetic detector 50.The connector 54 is connected to a wire harness (not shown). When electric power is supplied from the wire harness to the sensor 5, the sensor 5 outputs a voltage signal corresponding to the rotational position of the shaft 2. The voltage signal is transmitted to an electronic control unit (ECU) (not shown) via the wire harness. The ECU detects the rotational position of the shaft 2 based on the voltage signal.The position detection device 1 according to the present embodiment has operational advantages described below. (1) In the present embodiment, the sensor 5 is prevented from rotating around the engagement hole 36 disposed in the housing 3 by the anti-rotation pin 53 and is prevented from shifting on the straight line L to a position in a direction of the straight line L by the first engagement protrusion 521 that is in contact with the inner wall of the engagement hole 36. The magnetic detector 50 of the sensor 5 and the housing 3 are thus prevented from moving in position with respect to each other. Since the magnetic circuit unit 4 rotates with the shaft 2 supported by the housing 3, the magnetic detector 50 and the magnetic circuit unit 4 are prevented from shifting in positions with each other. The position detecting device 1 can thus accurately detect a rotation angle of the shaft 2.(2) In the present embodiment, the engagement protrusion 52 is in contact with the inner wall of the engagement hole 36 at a plurality of locations on a circumference of a circle centered on the magnetic detector 50.A portion of a metal mold is disposed between the magnetic detector 50 and the engaging protrusion 52 during injection molding, in which the sensor 5, the magnetic detector 50, and the engaging protrusion 52 are integrally formed. The structure of the engagement protrusion 52 can prevent the portion of the metal mold from decreasing in thickness for the entire circumference of the magnetic detector 50. The engagement protrusion 52 according to the present embodiment can extend the life of the metal mold used for injection molding, as compared to an engagement protrusion having a tubular shape.(3) In the present embodiment, the first engagement protrusion 521 is in contact with the inner wall of the engagement hole 36 on the straight line L. The second engagement protrusion 522 and the third engagement protrusion 523 are in contact with the inner wall of the engagement hole 36 at intervals of 120° or less in the circumferential direction around the magnetic detector 50 from a starting point at which the first engagement protrusion 521 is in contact with the inner wall of the engagement hole 36.Thus, the engagement protrusion 52 is in contact with the inner wall of the engagement hole 36 at three or more locations. The engagement protrusion 52 thus generates an engagement force having a magnitude equivalent to that of an engagement protrusion having a tubular shape. That is, the engagement protrusion 52 can prevent the magnetic detector 50 from shifting in position and tilting in all radial directions from the engagement hole 36, and prevent the housing 3 and the sensor 5 from moving relative to each other in all radial directions.(4) In the present embodiment, the anti-rotation hole 37 has an elongated hole shape whose longitudinal direction is parallel to the straight line L. The inner wall 371 of the anti-rotation hole 37 faces and contacts the anti-rotation pin 53 in the width direction.The position detection device 1 has the anti-rotation hole 37 that is an elongated hole and thereby allows the inner wall 371 of the anti-rotation hole 37 facing the width direction to reliably contact the anti-rotation pin 53 and can facilitate the mounting of the anti-rotation pin 53 in the anti-rotation hole 37.Since the inner wall 371 of the anti-rotation hole 37 facing the width direction reliably contacts the anti-rotation pin 53, the position detection device 1 can prevent the housing 3 and the sensor body 51 from rotating relative to each other around the engagement hole 36.(5) In the present embodiment, the engagement protrusion 52 is disposed to be symmetrical with respect to the plane S that is perpendicular to the magnetic detection surfaces of the magnetic detector 50.In this way, the magnetic detector 50 can be reliably prevented from being displaced in position and tilting with respect to the housing 3.(6) In the present embodiment, the connector 54 included in the sensor 5 is disposed at a position on an opposite side of the plane T 50 from the magnetic detector. The plane T is perpendicular to the straight line L and includes the center of the anti-rotation pin 53.Since the anti-rotation pin 53 is disposed between the connector 54 and the magnetic detector 50, vibration transmitted to the sensor body 51 is prevented from being transmitted from a harness connected to the connector 54 to the magnetic detector 50. The position detecting device 1 can thus prevent the magnetic detector 50 from shifting in position, and thereby accurately detect the rotation angle of the shaft 2.In the above-described embodiment, the engagement protrusion 52 is divided into three parts each having an arc shape. In another embodiment, the engagement protrusion 52 may not be divided and have a tubular shape. In this case, the engagement protrusion 52 may be in contact with the inner wall of the engagement hole 36 over the entire circumference.In another embodiment, the engagement protrusion 52 may be divided into two parts or three or more parts.In the above-described embodiment, the anti-rotation hole 37 has an elongated hole shape. In another embodiment, the anti-rotation hole 37 may have a circular shape or a polygonal shape.In the above-described embodiment, the anti-rotation pin 53 is disposed on the sensor 5, and the anti-rotation hole 37 is disposed in the housing 3. In another embodiment, the anti-rotation hole 37 may be disposed in the sensor 5, and the anti-rotation pin 53 may be disposed on the housing 3.In the above-described embodiment, the magnetic detector 50 includes two Hall ICs. In another embodiment, the magnetic detector 50 may include one Hall IC or three or more Hall ICs. The magnetic detector 50 may include a magnetoresistive sensor or the like.The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure without departing from the spirit of the invention.While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. On the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements. While the various elements are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less, or only a single element, are also within the scope of the present disclosure.

Claims

A position detecting device comprising: a shaft (2); a housing (3) supporting the shaft (2) rotatably about an axis of the shaft (2); a magnetic circuit unit (4) fixed to the shaft (2) and configured to rotate together with the shaft (2); a sensor (5) attached to the housing (3), the sensor (5) comprising: a sensor body (51); a magnetic detector (50) protruding from the sensor body (51) to the magnetic circuit unit (4); and at least one engagement protrusion (52, 521, 522, 523) extending from the sensor body (51) in the vicinity of the magnetic detector (50) and engaging with an engagement hole (36) disposed on the housing (3), a rotation preventing hole (37) disposed on at least one of the sensor body (51) and the housing (3) at a position spaced from the engagement hole (36) of the housing (3); and a rotation preventing pin (53) disposed on another one of the sensor body (51) and the housing (3), the rotation preventing pin (53) being engaged with the rotation preventing hole (37) to prevent the housing (3) and the sensor body (51) from rotating relative to each other about the engaging hole (36), wherein at least a part of the at least one engaging protrusion (52, 521, 522, 523) is in contact with an inner wall of the engaging hole (36) on a straight line (L) connecting a center of the magnetic detector (50) and a center of the rotation preventing pin (53), the at least one engaging protrusion (52, 521, 522, 523) comprising more than three engaging protrusions disposed on a circular circumference centered on the magnetic detector (50); a predetermined engagement protrusion (521) of the engagement protrusions (52, 521, 522, 523) is in contact with the inner wall of the engagement hole (36) on the straight line (L) connecting the center of the magnetic detector (50) and the center of the anti-rotation pin (53); and other engagement protrusions (522, 523) of the engagement protrusions (52, 521, 522, 523) are in contact with the inner wall of the engagement hole (36) at intervals of 120° or less in a circumferential direction from a starting point (P) where the predetermined engagement protrusion (521) of the engagement protrusions is in contact with the inner wall of the engagement hole (36).The position detection device according to claim 1, wherein the anti-rotation hole (37) has an elongated hole shape such that a longitudinal direction of the anti-rotation hole (37) is parallel to the straight line connecting the center of the magnetic detector (50) and the center of the anti-rotation pin (53), and the anti-rotation hole (37) has an inner wall (371) facing and contacting the anti-rotation pin (53) in a width direction orthogonal to the straight line.The position detecting device according to claim 1 or 2, wherein the at least one engaging protrusion is symmetrical with respect to a plane (S) perpendicular to a magnetic detecting surface of the magnetic detector (50).The position detection device according to any one of claims 1 to 3, wherein the sensor (5) includes a connector (54) disposed on the sensor body (51) at a position on a side of a plane (T) facing away from the magnetic detector (50), the plane (T) being perpendicular to the straight line connecting the center of the magnetic detector (50) and the center of the anti-rotation pin (53) and including the center of the anti-rotation pin (53).The position detection device according to any one of claims 1 to 4, wherein a distance from the center of the anti-rotation pin (53) to the axis of the shaft (2) is equal to or greater than a distance from the center of the magnetic detector (50) to the axis of the shaft (2).The position detection device according to any one of claims 1 to 5, wherein a straight line connecting the center of the magnetic detector (50) and the axis of the shaft (2) and a straight line connecting the center of the anti-rotation pin (53) and the axis of the shaft (2) form an angle of 90° or greater.

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