Sensing device for reducing contact amount between a stator and a housing to reduce noise

An embodiment relates to a sensing device comprising: a housing; a stator disposed within the housing; and a rotor disposed within the stator, wherein the stator comprises a body and a stator tooth coupled to the body, the housing comprises a first surface corresponding to a bottom surface of the stator tooth, and the first surface comprises a curved surface protruding toward the stator tooth. Accordingly, noise can be reduced by reducing the amount of contact between the stator and the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of PCT International Application No. PCT/KR2018/016430, filed on Dec. 21, 2018, which claims priority under 35 U.S.C. 119(a) to Patent Application Nos. 10-2018-0066204, filed in the Republic of Korea on Jun. 8, 2018 and 10-2018-0140530, filed in the Republic of Korea on Nov. 15, 2018, all of which are hereby expressly incorporated by reference into the present application.

TECHNICAL FIELD

An embodiment relates to a sensing device.

BACKGROUND ART

An electronic power steering system (hereinafter referred to as “EPS”) operates a motor in an electronic control unit according to operating conditions to ensure the turning stability and provide a high degree of resilience, thereby allowing the driver to drive safely.

In order to provide proper torque, the EPS includes a sensor assembly configured to measure torque of a steering shaft, a steering angle, and the like. The sensor assembly may include a torque sensor configured to measure torque acting on the steering shaft, an index sensor configured to measure an angular acceleration of the steering shaft, or the like. Also, the steering shaft may include an input shaft connected to a handle, an output shaft connected to a wheel-side power transmission configuration, and a torsion bar configured to connect the input shaft and the output shaft.

The torque sensor measures a degree of torsion of the torsion bar to measure the torque acting on the steering shaft. Also, the index sensor detects rotation of the output shaft to measure the angular acceleration of the steering shaft. In the sensor assembly, the torque sensor and the index sensor may be arranged together and integrally configured.

The torque sensor may include a housing, a rotor, a stator, and a collector to measure the torque.

Here, when the torque sensor is assembled to the EPS, contact may occur due to assembly tolerance between the housing and the stator. For example, one surface of the stator may come in surface contact with a bottom surface of the housing. Accordingly, there is a problem in that, during rotation of the stator, noise occurs due to the surface contact.

Also, in a case in which the amount of surface contact between the stator and the housing is increased to minimize clearance to induce safety with respect to the function of the torque sensor, there is a problem in that the noise is further increased.

Further, there is a problem in that noise is increased due to a material difference between a stator ring of the stator and the housing.

DISCLOSURE

Technical Problem

An embodiment is directed to providing a sensing device capable of, during contact between a stator and a housing, reducing the amount of contact to reduce noise.

Also, an embodiment is directed to providing a sensing device in which a non-magnetic metal is placed in a portion of the housing coming in contact with the stator so that the noise is further reduced, and simultaneously, magnetic field interference, which may occur during torque measurement, is avoided.

Objectives of the embodiments are not limited to the above-mentioned objectives, and other unmentioned objectives should be clearly understood by those of ordinary skill in the art from the description below.

Technical Solution

An embodiment provides a sensing device including a housing, a stator disposed in the housing, and a rotor disposed in the stator, wherein the stator includes a body and a stator tooth coupled to the body, the housing includes a first surface that corresponds to a bottom surface of the stator tooth, and the first surface includes a curved surface that protrudes toward the stator tooth.

Here, the protruding curved surface of the first surface may include a non-magnetic metal.

Alternatively, the housing may include a contact member disposed on the curved surface, and the contact member may include a curved surface that protrudes toward the bottom surface of the stator tooth.

Here, the protruding curved surface of the contact member may be disposed in a central region of a width of the first surface.

Also, the contact member may be formed in an arc shape in a circumferential direction.

Alternatively, the contact member may be provided as a plurality of contact members that are spaced apart in the circumferential direction.

Also, the contact member may protrude to be higher than the first surface.

Here, the curved surface of the first surface may be formed with a first curvature, the curved surface of the contact member may be formed with a second curvature, and the second curvature may be larger than the first curvature.

Also, the contact member may be formed of a non-magnetic metal.

Also, the contact member may be disposed in the housing using an insert injection method.

Meanwhile, the first surface may include a first protruding portion and a second protruding portion, and the first protruding portion and the second protruding portion may each include a curved surface.

Here, since the first protruding portion and the second protruding portion are disposed to be spaced apart in a radial direction, a groove may be formed between the first protruding portion and the second protruding portion, and based on a sum of a width of the first protruding portion, a width of the groove, and a width of the second protruding portion, the width of the groove may be 20% to 30% of the sum.

Also, the width (W4) of the groove may be 0.50 to 0.86 times the width (W3) of the first protruding portion.

An embodiment provides a sensing device including a housing, a stator disposed in the housing, and a rotor disposed in the stator, wherein the stator includes a body and a stator tooth coupled to the body, the housing includes a contact member that comes in contact with a bottom surface of the stator tooth, and the contact member is formed of a non-magnetic metal.

Here, the contact member may be formed in an arc shape in a circumferential direction.

Alternatively, the contact member may be provided as a plurality of contact members that are spaced apart in a circumferential direction.

Meanwhile, the stator of the sensing device may include a holder, a body disposed at one side of an outer circumferential surface of the holder, and a pair of stator teeth disposed on the body, wherein each stator tooth may include a stator tooth body, teeth that protrude from an inner circumferential surface of the stator tooth body in an axial direction, and protrusion parts that protrude from an outer circumferential surface of the stator tooth body in the axial direction.

Here, when viewed in a radial direction, the protrusion parts may be disposed between the teeth, and the protrusion parts may be provided as at least two protrusions that are disposed to be spaced apart from each other.

Also, the body may include a mold member and a flange portion that protrudes from an outer circumferential surface of the mold member in the radial direction, and the protrusion may be fixed to the flange portion by caulking.

An embodiment provides a sensing device including a housing, a stator disposed in the housing, a rotor disposed in the stator, a sensing portion configured to measure a magnetic field generated between the rotor and the stator, a shaft coupled to the stator, and a first gear disposed outside the shaft, wherein the shaft is disposed in an opening of the housing, the shaft comes in contact with the first gear, and a portion of an outer circumferential surface of the shaft comes in contact with an inner circumferential surface of the opening of the housing.

An embodiment provides a sensing device including a housing, a stator disposed in the housing, a rotor disposed in the stator, a sensing portion configured to measure a magnetic field generated between the rotor and the stator, a shaft coupled to the stator, and a first gear disposed outside the shaft, wherein the housing includes a first opening and a second opening that are disposed to be spaced apart in an axial direction, the shaft includes a first part and a second part that have different diameters, the first part comes in contact with the first gear, an outer diameter of the first part is smaller than a diameter of the first opening and larger than a diameter of the second opening, and an outer diameter of the second part is smaller than the diameter of the second opening.

Preferably, the first gear may include a first protrusion disposed on an inner circumferential surface of the gear, the shaft may include a first groove, and the first protrusion may be disposed in the first groove.

Preferably, the first gear may include a first protrusion disposed on an inner circumferential surface of the first gear, the shaft may include a first groove disposed at the first part, and the first protrusion may be disposed in the first groove.

Preferably, the shaft may include a third part disposed at a boundary between the first part and the second part, and an inlet of the first groove may be disposed at the third part.

Preferably, a height of the first groove may be larger than a height of the first protrusion.

Preferably, the third part may be disposed to be inclined.

Preferably, an inner circumferential surface of the second opening may include an inclined surface that comes in contact with the third part.

Preferably, the shaft may include a second protrusion, and a holder of the stator may include a second groove in which the second protrusion is disposed.

Preferably, in the axial direction, at least a portion of the holder of the stator may overlap the first groove.

Advantageous Effects

A sensing device according to an embodiment has an effect of significantly reducing noise due to friction. The sensing device can reduce the amount of contact between a stator and a housing to reduce noise.

Also, the sensing device can reduce noise between the stator and the housing by using a non-magnetic metal. Here, due to using the non-magnetic metal, the sensing device can avoid magnetic field interference that may occur during torque measurement.

In addition, since a component for fixing a first gear is omitted, the sensing device according to an embodiment has advantages in that the structure is simplified and the manufacturing cost is reduced.

MODES OF THE INVENTION

However, the technical idea of the present invention is not limited to some embodiments described herein and may be implemented in various different forms. One or more elements of different embodiments may be selectively combined or replaced within the scope of the technical idea of the present invention.

Also, unless otherwise defined, all terms including technical or scientific terms used in the embodiments of the present invention may be interpreted as having a meaning that may be commonly understood by those of ordinary skill in the art to which the present invention pertains, and a meaning of commonly-used terms, such as terms defined in dictionaries, may be interpreted in consideration of a meaning in the context of related technology.

Also, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In the present specification, a singular expression may include a plural expression unless the context clearly indicates otherwise, and “at least one (or one or more) of A, B, and C” may include one or more of any of the possible combinations of A, B, and C.

Also, in describing elements of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used.

Such terms are only intended to distinguish one element from another element, and the essence, order, sequence, or the like of the corresponding element is not limited by the terms.

Also, when a certain element is described as being “connected,” “coupled,” or “linked” to another element, this may include not only a case in which the element is directly connected, coupled, or linked to the other element but also a case in which the element is “connected,” “coupled,” or “linked” to the other element via another element present therebetween.

In addition, when a certain element is described as being formed or disposed above (on) or below (under)” another element, the term “above (on) or below (under)” not only includes a case in which two elements come in direct contact with each other but also includes a case in which one or more other elements are formed or disposed between the two elements. Also, the term “above (on) or below (under)” may include a downward direction as well as an upward direction with respect to one element.

Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. The same or corresponding elements will be denoted by the same reference numerals throughout the drawings and repeated descriptions thereof will be omitted.

First Embodiment

FIG.1is a perspective view illustrating a sensing device according to a first embodiment, andFIG.2is an exploded perspective view illustrating the sensing device according to the first embodiment. InFIG.2, the x-direction indicates an axial direction, and the y-direction indicates a radial direction. Also, the axial direction and the radial direction are perpendicular to each other.

Referring toFIGS.1and2, a sensing device1according to the first embodiment may include a housing100, which includes a first housing200and a second housing300, a stator400disposed in the housing100, a rotor500disposed in the stator400, a collector600disposed in the housing100, and a sensing portion700. Here, the stator400may include a holder410, a body420disposed at one side of an outer circumferential surface of the holder410, and two stator teeth430disposed on the body420. Also, the collector600disposed in the first housing200may be referred to as a “first collector600A.” In addition, the collector600disposed in the second housing300may be referred to as a “second collector600B.”

Here, the stator400may be connected to an output shaft (not illustrated), and the rotor500disposed inside the stator400may be connected to an input shaft (not illustrated), but the present invention is not necessarily limited thereto. Here, the inside may refer to a direction toward a center C in the radial direction, and the outside may refer to a direction opposite to the inside.

The housing100may form an exterior of the sensing device1.

The housing100may include the first housing200and the second housing300that are coupled to each other to have an accommodation space therein. Also, the stator400, the rotor500, the collector600, the sensing portion700, and the like may be disposed in the accommodation space.

As illustrated inFIGS.1and2, the first housing200and the second housing300may be disposed to face each other. Also, the first housing200and the second housing300may be formed of a synthetic resin material such as plastic.

One region of the first housing200may be disposed at a lower portion of the stator400.

When the stator400is connected to the output shaft, due to assembly tolerance, contact may occur between the stator400and the first housing200. Here, surface-to-surface contact may occur between the first housing200and the stator400, and thus, noise may occur when the stator400rotates. In particular, in the case of the surface-to-surface contact, there may be a problem in that noise increases due to a large friction area.

Therefore, the sensing device1may reduce the amount of contact between the first housing200and the stator400to reduce noise.

FIG.3is a perspective view illustrating a first embodiment of a first housing disposed in the sensing device according to the first embodiment,FIG.4is a bottom perspective view illustrating the first embodiment of the first housing disposed in the sensing device according to the first embodiment,FIG.5is a plan view illustrating the first embodiment of the first housing disposed in the sensing device according to the first embodiment, andFIG.6is a cross-sectional view illustrating the first embodiment of the first housing disposed in the sensing device according to the first embodiment. Here,FIG.6is a cross-sectional view taken along line A1-A1ofFIG.3.

Referring toFIGS.3to6, the first housing200according to the first embodiment may include a first housing body210in which a first through-hole211is formed, an inner sidewall220that protrudes from an inner surface212of the first housing body210in the axial direction, a first surface230disposed to face the stator tooth430of the stator400, and a second surface240at which the first collector600A is disposed. Here, the first surface230and the second surface240may be formed at the first housing body210.

Also, the first housing200may further include an outer sidewall250disposed to be spaced apart from the inner sidewall220in the radial direction. Also, the first housing200may further include a rib260disposed between the inner sidewall220and the outer sidewall250. Here, the first housing body210, the inner sidewall220, the outer sidewall250, and the rib260may be integrally formed. The first housing body210may include the first through-hole211, the inner surface212, and an outer surface213. Here, the first surface230and the second surface240may be disposed on the first housing body210. Also, the first housing body210may further include a support protrusion214configured to support a bent end portion of a leg620of the collector600.

The holder410of the stator400may be disposed through the first through-hole211. Also, the holder410may be connected to the output shaft.

The inner sidewall220may guide arrangement of the stator400.

The inner sidewall220may be formed to protrude from the inner surface212of the first housing body210in the axial direction and, as illustrated inFIG.5, formed in an arc shape in a plan view.

Referring toFIGS.3to6, the first surface230may be disposed to be adjacent to the first through-hole211. As illustrated inFIG.5, in consideration of the position of the stator tooth430in the radial direction with respect to the holder410of the stator400, the first surface230may be disposed to be spaced apart from the first through-hole211in the radial direction. Here, the first surface230may be disposed at an inner side of the inner sidewall220.

As illustrated inFIGS.3and6, the first surface230may be formed with a curved surface that protrudes toward the stator tooth430of the stator400in the axial direction. Accordingly, the amount of contact that occurs during contact between the first surface230and a bottom surface of the stator tooth430may be reduced.

Referring toFIG.6, the first surface230may be formed to a predetermined height H1with respect to a virtual line L1that connects an outer corner231and an inner corner232of the first surface230including the curved surface. Here, the height H1may be 0.06 to 0.07 times a width W1of the first surface230in the radial direction. Here, the width W1of the first surface230of the first housing200according to the first embodiment may be referred to as a “first width.” Also, the height H1of the first surface230of the first housing200according to the first embodiment may be referred to as a “first height.”

The height H1of the first surface230may be adjusted due to a separation relationship with the bottom surface of the stator tooth430. For example, since a separation distance between the first surface230and the bottom surface of the stator tooth430affects performance, the height H1of the first surface230may be adjusted due to the separation distance in design.

Also, the curved surface may be formed with a predetermined curvature 1/R1 in a cross-sectional view so that a central region of the curved surface protrudes. Accordingly, the first surface230and the bottom surface of the stator tooth430may also come in line contact.

Referring toFIG.5, when viewed from the stator400side, the first surface230may be formed in an arc shape in a plan view. As illustrated inFIG.5, the first surface230may be formed in a C-shape in a plan view.

Referring toFIG.3, the first surface230may be formed to be higher than the second surface240. Accordingly, even when the collector600is disposed at the second surface240, the bottom surface of the stator tooth430may come in contact with the first surface230.

Meanwhile, the protruding curved surface of the first surface230may include a non-magnetic metal. Accordingly, the curved surface including the non-magnetic metal may come in contact with the bottom surface of the stator tooth430. Here, the non-magnetic metal may include any one of copper, lead, tin, zinc, gold, platinum, mercury or a combination thereof.

The non-magnetic metal may improve surface roughness and lubricating performance. Also, the non-magnetic metal may improve performance of resistance to wear due to contact. Accordingly, the non-magnetic metal may reduce noise that occurs due to friction with the first surface230and the stator tooth430of the stator400.

The non-magnetic metal may be provided as a member disposed at the protruding curved surface of the first surface230. Alternatively, the non-magnetic metal powder may be applied on the protruding curved surface of the first surface230. Alternatively, the first housing200may be formed to include the non-magnetic metal so that the non-magnetic metal is disposed at the protruding curved surface of the first surface230.

The first collector600A may be disposed on the second surface240. The second surface240may be formed to be lower than the first surface230.

Referring toFIG.5, the second surface240may be disposed between both end portions of the first surface230formed in a C-shape in a plan view in the circumferential direction.

The outer sidewall250may form an exterior of the first housing200together with the first housing body210.

The outer sidewall250may be formed to protrude from the inner surface212of the first housing body210in the axial direction. As illustrated inFIG.3, the outer sidewall250may be formed to protrude from an outer side surface of the first housing body210toward the second housing300in the axial direction.

Also, the outer sidewall250may be disposed to be spaced apart from the inner sidewall220in the radial direction. Here, the outer sidewall250may be disposed outside the inner sidewall220.

The rib260may improve a rigidity of the first housing200. Accordingly, using the rib260, the first housing200may deal with deformation of the first housing200, which is formed of a synthetic resin material, or an external force applied from the outside.

The rib260may be disposed between the inner sidewall220and the outer sidewall250. Here, the rib260may be formed to protrude from the inner surface212in the axial direction. As illustrated inFIGS.3and5, the rib260may be formed in a lattice shape.

FIG.7is a perspective view illustrating a second embodiment of the first housing disposed in the sensing device according to the first embodiment,FIG.8is a plan view illustrating the second embodiment of the first housing disposed in the sensing device according to the first embodiment, andFIG.9is a cross-sectional view illustrating the second embodiment of the first housing disposed in the sensing device according to the first embodiment. Here,FIG.9is a cross-sectional view taken along line A2-A2ofFIG.7.

In describing a first housing200A according to the second embodiment with reference toFIGS.7to9, elements which are the same as those of the first housing200according to the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

The first housing200A according to the second embodiment may be used in place of the first housing200according to the first embodiment in the sensing device1.

Referring toFIGS.7to9, the first housing200A according to the second embodiment may include a first housing body210in which a first through-hole211is formed, an inner sidewall220that protrudes from an inner surface212of the first housing body210in the axial direction, a first surface230disposed to face the stator tooth430of the stator400, a second surface240at which the first collector600A is disposed, and a contact member270.

Also, the first housing200A may further include an outer sidewall250disposed to be spaced apart from the inner sidewall220in the radial direction. Also, the first housing200A may further include a rib260disposed between the inner sidewall220and the outer sidewall250.

The contact member270may be disposed on the first surface230. Also, the contact member270may come in contact with the bottom surface of the stator tooth430. Here, the first surface230may be formed with a curved surface.

The contact member270may be disposed in a central region of the first surface230in the radial direction. Accordingly, the contact member270may be formed in an arc shape in a plan view. As illustrated inFIG.8, the contact member270may be formed in a C-shape in a plan view.

Referring toFIGS.7to9, the contact member270may be disposed in a central region of a width W1of the first surface230. Here, the contact member270may be formed to have a predetermined width W2in the radial direction. Here, the width W2of the contact member270may be referred to as a “second width.”

Also, the width W2of the contact member270may be 0.2 to 0.3 times the width W1of the first surface230.

Referring toFIG.7, the contact member270may include a curved surface271that protrudes toward the bottom surface of the stator tooth430.

The curved surface271of the contact member270may be formed with a predetermined curvature 1/R1 in a cross-sectional view so that a central region of the curved surface271protrudes. Here, the curvature of the curved surface271of the contact member270may be the same as the curvature of the first surface230formed with a curved surface.

Also, the contact member270may be formed to a predetermined height H1with respect to a virtual line L1that connects an outer corner231and an inner corner232of the first surface230. Here, a case in which the contact member270is formed to the predetermined height H1has been described as an example, but the present invention is not necessarily limited thereto. For example, the contact member270may be formed to a height smaller than the predetermined height H1.

As illustrated inFIG.9, the curved surface271of the contact member270may be formed to the predetermined height H1with respect to the virtual line L1.

Also, as illustrated inFIG.9, one region of the contact member270may be disposed inside the first housing body210. Here, the contact member270may be disposed in the first housing200A using an insert injection method. Accordingly, since the contact member270may be supported by the first housing body210, even when an external force is applied to the contact member270, the contact member270may deal with the external force. Also, due to being supported by the first housing body210, the contact member270is prevented from falling out of the first housing200A.

Meanwhile, the contact member270may be formed of a non-magnetic metal.

The contact member270formed of the non-magnetic metal material may improve surface roughness and lubricating performance. Accordingly, the contact member270may reduce noise generated due to friction. Also, the contact member270formed of the non-magnetic metal material may improve performance of resistance to wear due to contact.

FIG.10is a view illustrating a modified example of arrangement of a contact member in the second embodiment of the first housing disposed in the sensing device according to the first embodiment.FIG.10is a cross-sectional view taken along line A2-A2ofFIG.7.

The contact member270of the first housing200A may be disposed in the central region of the first surface230. For example, the contact member270may be disposed in the central region of the width W1of the first surface230. Here, the contact member270may be formed to have a predetermined width W2in the radial direction.

The contact member270may be formed in an arc shape in a plan view. As illustrated inFIG.8, the contact member270may be formed in a C-shape in a plan view.

Also, a portion of the contact member270may protrude to be higher than the first surface230. Accordingly, the curved surface271of the contact member270may be disposed to be higher than the first surface230.

Referring toFIG.10, the contact member270may be formed to the predetermined height H1with respect to the virtual line L1that connects the outer corner231and the inner corner232of the first surface230. As illustrated inFIG.10, the curved surface271of the contact member270may be formed to the predetermined height H1with respect to the virtual line L1. Here, the first surface230may be formed to a predetermined height H2with respect to the virtual line L1.

Here, the height H1of the curved surface271of the contact member270may be referred to as a “second height,” and the predetermined height H2of the first surface230may be referred to as a “third height.” Accordingly, the second height is larger than the third height.

Meanwhile, a curvature of the first surface230formed with a curved surface may be different from a curvature of the curved surface271of the contact member270.

Referring toFIG.10, the first surface230may be formed to have a predetermined curvature 1/R1. Also, the curved surface271of the contact member270may be formed to have a predetermined curvature 1/R2. Here, the curvature 1/R1 of the first surface230may be referred to as a “first curvature,” and the curvature 1/R2 of the curved surface271of the contact member270may be referred to as a “second curvature.” Accordingly, the first curvature may be different from the second curvature. Specifically, the second curvature may be larger than the first curvature.

A case in which the contact member270is formed with the curved surface271having the predetermined curvature 1/R2 has been described as an example, but the present invention is not necessarily limited thereto. For example, in a case in which the contact member270is disposed to be higher than the first surface230, an upper surface of the contact member270that comes in contact with the bottom surface of the stator400may also be formed with a flat surface. Although the amount of contact increases as compared to when the contact member270is formed with a curved surface, since the contact member270is disposed in one region of the first surface230, the amount of contact is reduced as compared to the conventional case in which surface-to-surface contact occurs.

Also, in a case in which the curved surface271of the contact member270is disposed to be higher than the first surface230, the first surface230may also be formed with a flat surface.

FIG.11is a view illustrating another modified example of the arrangement of the contact member in the second embodiment of the first housing disposed in the sensing device according to the first embodiment.FIG.11is a perspective view illustrating the arrangement of the contact member in the second embodiment of the first housing disposed in the sensing device according to the first embodiment.

Referring toFIG.11, the contact member270of the first housing200A may be provided as a plurality of contact members270that are spaced apart in the circumferential direction.

Here, even in a case in which the height of the contact member270and the height of the first surface230are the same with respect to the virtual line L1that connects the outer corner231and the inner corner232of the first surface230, since the contact member270is formed of the non-magnetic metal material, the contact member270may reduce the noise generated due to friction.

Alternatively, in a case in which the height of the contact member270is larger than the height of the first surface230with respect to the virtual line L1connecting the outer corner231and the inner corner232of the first surface230, the amount of contact between the bottom surface of the stator tooth430and the contact members270, which are disposed to be spaced apart from each other in the circumferential direction as illustrated inFIG.11, is further reduced.

FIG.12is a perspective view illustrating a third embodiment of the first housing disposed in the sensing device according to the first embodiment,FIG.13is a plan view illustrating the third embodiment of the first housing disposed in the sensing device according to the first embodiment, andFIG.14is a cross-sectional view illustrating the third embodiment of the first housing disposed in the sensing device according to the first embodiment. Here,FIG.14is a cross-sectional view taken along line A3-A3ofFIG.12.

In describing a first housing200B according to the third embodiment with reference toFIGS.12to14, elements which are the same as those of the first housing200according to the first embodiment and the first housing200A according to the second embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

The first housing200B according to the third embodiment may be used in place of the first housing200according to the first embodiment in the sensing device1.

Referring toFIGS.12to14, the first housing200B according to the third embodiment may include a first housing body210in which a first through-hole211is formed, an inner sidewall220that protrudes from an inner surface212of the first housing body210in the axial direction, a first surface230disposed to face the stator tooth430of the stator400, and a second surface240at which the first collector600A is disposed. Here, the first surface230may include a first protruding portion233and a second protruding portion234that are disposed to be spaced apart from each other in the radial direction. Also, in consideration of the amount of contact, the first protruding portion233and the second protruding portion234may each include a curved surface.

Also, the first housing200B may further include an outer sidewall250disposed to be spaced apart from the inner sidewall220in the radial direction. Also, the first housing200B may further include a rib260disposed between the inner sidewall220and the outer sidewall250.

The first housing200B may include the first protruding portion233and the second protruding portion234disposed inside the first protruding portion233. Here, the first protruding portion233and the second protruding portion234may each extend to protrude from the first housing body210in the axial direction with respect to the inner surface212of the first housing body210.

Since the first protruding portion233and the second protruding portion234are disposed to be spaced apart in the radial direction, a groove235may be formed between the first protruding portion233and the second protruding portion234.

Here, the first protruding portion233may include a curved surface233aformed with a predetermined curvature. Also, the second protruding portion234may include a curved surface234aformed with a predetermined curvature. Here, the curvature of the curved surface233aof the first protruding portion233and the curvature of the curved surface234aof the second protruding portion234may be the same, but the present invention is not necessarily limited thereto.

As illustrated inFIG.14, the curvature of the curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234, which are formed with the same curvature 1/R3, may be referred to as a “third curvature.”

The curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234, which are disposed with the groove235disposed therebetween, may each come in contact with the bottom surface of the stator tooth430. Accordingly, movement of the stator400due to rotation thereof may be minimized.

The first protruding portion233and the second protruding portion234may each be formed in a C-shape in a plan view. Accordingly, the groove235may also be formed in a C-shape in a plan view.

Referring toFIG.14, the second surface240, on which the first collector600A is disposed, is disposed between one side end and the other side end of each of the first protruding portion233and the second protruding portion234in the circumferential direction. Accordingly, one region of the first collector600A is disposed between the one side end and the other side end of each of the first protruding portion233and the second protruding portion234.

As illustrated inFIG.13, the one side end and the other side end of the first protruding portion233may form a first angle θ1with respect to the center C. Also, the one side end and the other side end of the second protruding portion234may form a second angle θ2with respect to the center C. The second angle θ2is smaller than the first angle θ1. Here, the center C may be a center C of the first through-hole211. Also, the center C may be a center C of the sensing device1.

Meanwhile, the first protruding portion233and the second protruding portion234may be formed with the same width in the radial direction, but the present invention is not necessarily limited thereto. In consideration of the mobility of the stator400due to contact between the bottom surface of the stator tooth430and each of the first protruding portion233and the second protruding portion234, the first protruding portion233and the second protruding portion234may also be formed with different widths.

Based on a sum of a width W3of the first protruding portion233, a width W4of the groove235, and the width W3of the second protruding portion234, the width W4of the groove235may be 20% to 30% of the sum.

The width W4of the groove235may be 0.50 to 0.86 times the width W3of the first protruding portion233. For example, a ratio of W3to W4may be in a range of 1:0.50 to 1:0.86.

Accordingly, due to the groove235, the amount of contact with the bottom surface of the stator tooth430is reduced.

That is, in consideration of the amount of noise generated in the sensing device1due to rotation of the stator400and the stability of supporting the stator400by the first protruding portion233and the second protruding portion234, it is preferable that the width W4of the groove235is 0.50 to 0.86 times the width W3of the first protruding portion233.

Also, with respect to a bottom surface235aof the groove235, the curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234may each be formed to a predetermined height H1. Here, the height H1of each of the curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234may be 0.06 to 0.07 times the sum of the width W3of the first protruding portion233, the width W4of the groove235, and the width W3of the second protruding portion234.

Meanwhile, a lubricating member (not illustrated) may be applied on an upper portion of each of the first protruding portion233and the second protruding portion234.

The lubricating member further reduces noise generated during rotation of the stator400. Here, grease may be used as the lubricating member.

Also, when the stator400rotates, the groove235may prevent the lubricating member from scattering or falling and allow the lubricating member to be concentrated on the curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234.

FIG.15is a perspective view illustrating a fourth embodiment of the first housing disposed in the sensing device according to the first embodiment, andFIG.16is a cross-sectional view illustrating the fourth embodiment of the first housing disposed in the sensing device according to the first embodiment. Here,FIG.16is a cross-sectional view taken along line A4-A4ofFIG.15.

In describing a first housing200C according to the fourth embodiment with reference toFIGS.15and16, elements which are the same as those of the first housing200according to the first embodiment and the first housing200A according to the second embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

The first housing200C according to the fourth embodiment may be used in place of the first housing200according to the first embodiment in the sensing device1.

Referring toFIGS.15and16, the first housing200C according to the fourth embodiment may include a first housing body210in which a first through-hole211is formed, an inner sidewall220that protrudes from an inner surface212of the first housing body210in the axial direction, a second surface240at which the first collector600A is disposed, a third surface280disposed below the stator tooth430of the stator400, and a contact member290disposed at the third surface280to face the stator tooth430of the stator400.

Here, since the contact member270of the first housing200A according to the second embodiment may be referred to as a “first contact member,” the contact member290of the first housing200C according to the fourth embodiment may be referred to as a “second contact member.” Comparing the contact member290of the first housing200C and the contact member270of the first housing200A, there is a difference in that the contact member290of the first housing200C does not have a portion disposed inside the first housing body210. Accordingly, the contact member290of the first housing200C may be fixed to the third surface280using a fixing member such as an adhesive.

Also, the first housing200C may further include an outer sidewall250disposed to be spaced apart from the inner sidewall220in the radial direction. Also, the first housing200C may further include a rib260disposed between the inner sidewall220and the outer sidewall250.

The third surface280may be formed on the first housing body210.

The third surface280may be disposed to be spaced apart from the first through-hole211in the radial direction. Here, the third surface280may be disposed at an inner side of the inner sidewall220. That is, the third surface280may be disposed between the first through-hole211and the inner sidewall220.

As illustrated inFIGS.15and16, the third surface280may be formed with a flat surface. Also, the third surface280may be formed to be higher than the second surface240.

The contact member290of the first housing200C may be disposed at the third surface280. Also, the contact member290may come in contact with the bottom surface of the stator tooth430.

The contact member290may be formed in an arc shape in a plan view. For example, the contact member290may be formed in a C-shape in a plan view. Here, the contact member290may be formed to have a predetermined width W1in the radial direction. Accordingly, the width of the contact member290may be the same as the width of the first surface230. Here, the width of the first surface230in the radial direction may be the same as the width of the third surface280in the radial direction.

The contact member290may be formed of a non-magnetic metal.

The contact member290formed of the non-magnetic metal material may improve surface roughness and lubricating performance. Accordingly, the contact member290may reduce noise generated due to friction. Also, the contact member290formed of the non-magnetic metal material may improve performance of resistance to wear due to contact.

Referring toFIG.16, an upper surface291of the contact member290may be formed with a flat surface or a curved surface.

Since the contact member290may be formed of a non-magnetic metal even when the upper surface291of the contact member290is formed with a flat surface as illustrated inFIG.16, the contact member290may reduce the noise due to contact.

Alternatively, the upper surface291of the contact member290may be formed with a curved surface.

The upper surface291of the contact member290formed with the curved surface may be formed to have a predetermined curvature 1/R1 in a cross-sectional view so that a central region of the upper surface291protrudes. For example, the curvature of the upper surface291of the contact member290may be formed to be the same as the curvature of the first surface230of the first housing200according to the first embodiment.

Also, the contact member290may be formed to the predetermined height H1with respect to the third surface280. Accordingly, the height of the upper surface291of the contact member290may be formed to be the same as the height of the first surface230of the first housing200according to the first embodiment.

Referring toFIG.16, the height H1of the contact member290may be 0.06 to 0.07 times the width W1of the contact member290in the radial direction.

Referring toFIGS.1and2, the second housing300may be disposed above the first housing200.

A second through-hole310for arrangement of the rotor500may be formed in the second housing300. Here, the rotor500may be connected to an input shaft, and the input shaft may be connected to a steering handle.

Also, the second collector600B may be disposed at an inner surface of the second housing300.

The stator400may be rotatably disposed inside the housing100. Here, the stator400is disposed outside the rotor500.

FIG.17is a perspective view illustrating a stator disposed in the sensing device according to the first embodiment,FIG.18is an exploded perspective view illustrating the stator disposed in the sensing device according to the first embodiment,FIG.19is a lateral view illustrating a stator tooth disposed in the sensing device according to the first embodiment, andFIG.20is a view illustrating a bent protrusion part of the stator disposed in the sensing device according to the first embodiment.

Referring toFIG.2andFIGS.17to20, the stator400may include the holder410connected to the output shaft, the body420disposed at the one side of the outer circumferential surface of the holder410, and the pair of stator teeth430disposed on the body420. Here, the stator tooth430may be fixed to the body420. Also, the stator tooth430may be referred to as a “stator ring.”

The holder410may be disposed to be connected to an output shaft of an electronic power steering system (EPS). Accordingly, the holder410rotates in association with rotation of the output shaft.

Here, the holder410may be formed of a metal material. However, the present invention is not necessarily limited thereto, and of course, another material may be used in consideration of a predetermined strength or more to allow the output shaft to be fitted and fixed.

The body420may be disposed at one side end portion of the holder410. For example, the body420may be disposed at one side end portion of the holder410by using an insert injection method or the like using synthetic resin such as resin.

The body420may include a mold member421having a cylindrical shape, a flange portion422that protrudes from an outer circumferential surface of the mold member421in the radial direction, and an insertion hole423formed in the mold member421. Here, the insertion hole423may be referred to as a “third through-hole” or “hole.”

The flange portion422may be formed to protrude from the cylindrical mold member421outward in the circumferential direction (in the radial direction).

A pair of flange portions422may be disposed to be spaced apart vertically. As illustrated inFIG.18, the pair of flange portions422may be disposed at an upper end and a lower end of the mold member421so as to protrude outward.

As illustrated inFIG.18, a plurality of insertion holes423may be formed at predetermined intervals in the mold member421in the circumferential direction with respect to the center C.

Also, as teeth432of the stator teeth430are inserted into the insertion holes423, the teeth432of the stator teeth430may be disposed at an inner surface of the body420. As illustrated inFIG.17, the teeth432of the stator teeth430may be disposed in an inner surface of the mold member421.

The stator teeth430may be provided as the pair of stator teeth430.

Each stator tooth430may include a stator tooth body431, a plurality of teeth432disposed to be spaced apart along an inner circumferential surface of the stator tooth body431, and protrusion parts433disposed to be spaced apart along an outer circumferential surface of the stator tooth body431. Here, the teeth432and the protrusion parts433may be formed to protrude in the same direction. Also, the stator tooth body431, the teeth432, and the protrusion parts433may be integrally formed.

The stator tooth body431may be formed in a ring shape.

A bottom surface431aof the stator tooth body431may be disposed to face the first housing200. InFIG.17, the bottom surface431amay be one surface of the stator tooth body431that is formed on the stator tooth430disposed at a lower side with respect to the body420. Alternatively, as illustrated inFIG.18, the bottom surface431amay be one surface of the stator tooth body431that is disposed at the holder410side with respect to the body420.

The bottom surface431amay be disposed to face the first surface230of the first housing200according to the first embodiment. Accordingly, the bottom surface431amay come in contact with the first surface230formed with a curved surface.

Alternatively, the bottom surface431amay be disposed to face the contact member270of the first housing200A according to the second embodiment. Accordingly, the bottom surface431amay come in contact with the curved surface271of the contact member270.

Alternatively, the bottom surface431amay be disposed to face the first protruding portion233and the second protruding portion234of the first housing200B according to the third embodiment. Accordingly, the bottom surface431amay come in contact with at least any one of the curved surface233aof the first protruding portion233and the curved surface234aof the second protruding portion234.

Alternatively, the bottom surface431amay be disposed to face the contact member290of the first housing200C according to the fourth embodiment. Accordingly, the bottom surface431amay come in contact with the upper surface291of the contact member290.

The teeth432may be formed to protrude from the inner circumferential surface of the stator tooth body431in the axial direction.

As illustrated inFIG.18, any one of the stator teeth430may be disposed at one side (upper portion) of the body420, and the other one may be disposed at the other side (lower portion) of the body420. Accordingly, as illustrated inFIG.17, the teeth432of the stator teeth430may be disposed at predetermined intervals so as to be engaged with each other.

The protrusion parts433may be formed to protrude from the outer circumferential surface of the stator tooth body431in the axial direction.

The protrusion parts433may be fixed to an outer surface of the body420by caulking. Since the protrusion parts433are coupled to the outer surface of the body420using a caulking method in which one side of each protrusion part433is pressed and bent, assembly tolerance does not occur.

As illustrated inFIG.20, the protrusion part433may be fixed to the flange portion422of the body420by caulking. Accordingly, a coupling force of the protrusion part433to the body420may be improved.

Meanwhile, the teeth432and the protrusion parts433may be disposed to be spaced apart from each other in the radial direction.

When viewed in the radial direction (y-direction), the protrusion parts433may be disposed between the teeth432. Since a magnetic field is affected when the protrusion parts433are disposed to overlap the teeth432when viewed in the radial direction (y-direction), the protrusion parts433may be disposed between the teeth432to prevent an influence on the magnetic field.

The protrusion parts433may be provided as at least two first protrusions433adisposed to be spaced apart from each other.

Referring toFIGS.18to20, the protrusion parts433may implement a double caulking structure to further improve the coupling force of the protrusion part433to the body420. Also, since the double caulking structure increases a contact area with the body420, a caulking force in a rotational direction of the protrusion parts433may be improved.

As illustrated inFIG.19, the two first protrusions433amay be disposed to be spaced apart from each other at a preset separation distance d. Also, the first protrusion433amay be formed in a quadrangular shape, and a height of the first protrusion433ais smaller than a height of the tooth432. Here, the separation distance d may be formed according to the following equation.
d:W=1:1.5

As illustrated inFIG.19, a ratio of the separation distance d and a width W of the first protrusion433amay be 1:1.5. That is, by placing the first protrusions433ato be adjacent to each other while being spaced apart at the separation distance d, the caulking force in the rotational direction of the protrusion parts433may be improved. Further, since one region of the body420is disposed between the first protrusions433a, a coupling force between the body420and the stator teeth430is improved.

FIG.21is a lateral view illustrating another embodiment of the stator tooth disposed in the sensing device according to the first embodiment. A stator tooth430aaccording to another embodiment may be disposed in the body420in place of the above-described stator tooth430.

Hereinafter, in describing the stator tooth430a, elements which are the same as those of the stator tooth430will be denoted by the same reference numerals, and detailed description thereof will be omitted.

Referring toFIG.21, the stator tooth430aaccording to another embodiment may include a stator tooth body431, a plurality of teeth432, and protrusion parts433disposed to be spaced apart from each other along an outer circumferential surface of the stator tooth body431. Here, the protrusion parts433may be provided as at least two second protrusions433bdisposed to be spaced apart from each other.

The second protrusion433bmay have one side surface formed to be inclined at a predetermined angle θ3.

As illustrated inFIG.21, the one side surface of the second protrusion433bmay be formed to be inclined at the predetermined angle θ3with respect to a virtual line L2that passes through the center of the protrusion. Accordingly, since a contact area between the second protrusion433band the body420is increased, a caulking force in a rotational direction of the protrusion parts433may be improved.

As illustrated inFIG.21, the second protrusion433bmay have a width that is narrow at the stator tooth body431-side and that increases in a direction moving away from the stator tooth body431. For example, the second protrusion433bmay be formed in trapezoidal shape. However, the present invention is not necessarily limited thereto, and of course, the second protrusion433bmay be formed in various other shapes in consideration of the contact area with the body420.

Meanwhile, since the protrusion part433is fixed to an outer surface of the body420by caulking of the protrusion part433, as illustrated inFIG.20, a groove422amay be formed in the flange portion422of the body420. Here, the groove422ais formed so that the number of grooves422acorresponds to the number of protrusions433aand433b. Accordingly, catching step surfaces422bformed due to the grooves422amay be disposed to face each other.

Also, the protrusions433aand433bare pressed against the catching step surfaces422b.

Therefore, the catching step surfaces422bmay support side surfaces of the protrusions433aand433bto improve a caulking force in the rotational direction. In particular, since the contact area between the second protrusion433band the catching step surface422bis increased, the caulking force and support force in the rotational direction are further improved as compared to the first protrusion433a.

A case in which the groove422ais formed by caulking the protrusion part433has been described as an example, but the present invention is not necessarily limited thereto. For example, the groove422amay be formed in the flange portion422first, and the shapes of the protrusions433aand433bmay be matched to the shape of the groove422ato fix the stator teeth430and430ato the body420. Here, end portions of the protrusions433aand433bmay be bent to place the protrusions433aand433bin the groove422a. Accordingly, the protrusions433aand433bmay be supported by the catching step surface422b.

The rotor500is disposed inside the stator400. Here, the rotor500is connected to an input shaft of a steering shaft. Accordingly, the rotor500may rotate in association with rotation of the input shaft.

The rotor500may include a cylindrical yoke510and a magnet520disposed on the yoke510. The input shaft may be inserted into the yoke510. Also, the magnet520may be disposed outside the yoke510.

The magnet520may be adhered and fixed or press-fitted and fixed to an outer circumferential surface of the yoke510.

The collector600collects a flux of the stator400. Here, the collector600may be formed of a metal material, and two collectors600may be fixed inside the housing100. Referring toFIG.2, the collector600may be disposed inside each of the first housing200and the second housing300.

The collector600may be disposed to be adjacent to the stator tooth430. Here, being disposed to be adjacent may refer to being disposed to be spaced apart at a predetermined distance.

The collector600may include a plate610and a leg620that extends to protrude from the plate610.

One surface of the plate610may be disposed on the second surface240.

The leg620may extend from the plate610in the axial direction. Also, as illustrated inFIG.2, an end portion of the leg620may be bent outward.

The sensing portion700measures a magnetic field generated between the stator400and the rotor500. The sensing portion700is connected to an electronic control unit (ECU) of a motor, which assists steering force, to allow torque to be calculated on the basis of a change in the measured magnetic field.

The sensing portion700may include a circuit board710and a sensor720. Here, the sensor720may be disposed at a position that corresponds to the end portion of the leg620of the collector600.

The sensor720disposed on the circuit board710may detect a change in the magnetic field. A Hall integrated circuit (IC) may be provided as the sensor. Accordingly, the sensor720detects magnetization of the stator400that occurs due to an electrical interaction between the magnet520of the rotor500and the stator400. Also, the sensing device1may measure torque on the basis of the detected magnetization.

The stator400, the rotor500, and the sensor720are components to measure torque. Due to a difference between rotation amounts of the input shaft and the output shaft, torsion may occur in a torsion bar of the input shaft and the output shaft. When the torsion occurs, the rotation amount of the magnet520of the rotor500and the rotation amount of the stator400become different. Therefore, since surfaces of the magnet520and the stator tooth430that oppose each other change, a change in magnetization occurs. Accordingly, the sensor720may detect the change in magnetization to measure torque acting on the steering shaft.

Second Embodiment

FIG.22is a view illustrating a sensing device according to a second embodiment.

Referring toFIG.22, the sensing device according to the second embodiment may include a rotor1100, a stator1200, a sensing portion1300, a shaft1400, a housing1500, a first gear1600, and a second gear1700.

The rotor1100is disposed inside the stator1200. The rotor1100is connected to an input shaft of a steering shaft. Here, the input shaft may refer to a steering shaft connected to a steering handle of a vehicle. The rotor1100may include a cylindrical yoke1110and a first magnet1120disposed on the yoke1110. The input shaft is inserted into the yoke1110. Also, the first magnet1120may be disposed outside the yoke1110. The first magnet1120may be adhered and fixed or press-fitted and fixed to an outer circumferential surface of the yoke1110.

The stator1200is disposed outside the rotor1100. The stator1200may include a ring-shaped stator tooth1210and a holder1220. Two stator teeth1210may be fixed to an upper side and a lower side of the holder1220, respectively. Each stator tooth1210may include a plurality of teeth1211disposed to face the first magnet1120. The holder1220is coupled to the shaft1400. The holder1220may be made of a plastic resin.

The sensing portion1300may include a circuit board1310and a collector1320.

The circuit board1310includes a Hall sensor1311. The Hall sensor1311detects magnetization of the stator1200that occurs due to an electrical interaction between the first magnet1120of the rotor1100and the stator1200. The circuit board1310may be fastened to a separate sensor housing, a housing of an external device, or the like and fixed.

The collector1320collects a flux of the stator1200. The collector1320may include an upper collector1320A and a lower collector1320B. The upper collector1320A and the lower collector1320B may be disposed to be spaced apart in the axial direction of the rotor1100. Also, the Hall sensor1311is disposed between the upper collector1320A and the lower collector1320B in the axial direction of the rotor1100.

The shaft1400is coupled to the holder1220. The shaft1400may be connected to an output shaft of the steering shaft. Here, the output shaft may refer to a steering shaft connected to a wheel-side power transmission configuration. Therefore, the stator1200is connected to the output shaft and rotates together with the output shaft. The shaft1400may be made of a metal material.

The housing1500may include a first housing1510, a second housing1520, and a third housing1530. The first housing1510may be disposed between the second housing1520and the third housing1530in the axial direction. The second gear1700may be disposed in the first housing1510. The second gear1700is engaged with the first gear1600. The first housing1510includes a first opening1511. The shaft1400passes through the first opening1511. The lower collector1320B is disposed in the first housing1510. The second housing1520is stacked on the first housing1510. The second housing1520includes a second opening1521. The shaft1400passes through the second opening1521. The first opening1511and the second opening1521are aligned in the axial direction. The third housing1530is stacked on the second housing1520. The third housing1530may include a third opening1531. The rotor1100passes through the third opening1531. The circuit board1310and the upper collector1320A may be disposed in the third housing1530.

The first gear1600is coupled to the shaft1400. The first gear1600rotates together with the shaft1400when the stator1200rotates. The first gear1600is engaged with the second gear1700. The second gear1700may be provided as a plurality of second gears1700. All of the second gears1700may be engaged with the first gear1600, or some of the plurality of second gears1700may be engaged with the first gear1600while the remaining second gears1700are disposed to be engaged with other second gears1700. When the stator1200rotates, the first gear1600and the second gear1700rotate at a gear ratio. The second gear1700includes a second magnet1710. When the second gear1700rotates, the second magnet1710rotates together. The Hall sensor1311detects a change in a magnetic flux due to rotation of the second magnet1710.

FIG.23is a view illustrating a shaft, andFIG.24is a lateral cross-sectional view of the shaft.

Referring toFIGS.23and24, the shaft1400includes a first part1400A, a second part1400B, and a third part1400C. An outer diameter D1of the first part1400A may be larger than an outer diameter D2of the second part1400B. The first part1400A is for coupling with the first gear1600. Also, the first part1400A is for coming in contact with the first opening1511of the first housing1510. The third part1400C connects the first part1400A and the second part1400B. The third part1400C is disposed at a boundary between the first part1400A and the second part1400B. The third part1400C may include an inclined surface.

The first part1400A includes a first groove1410formed in an outer circumferential surface. The first groove1410is for coupling between the shaft1400and the first gear1600. A first protrusion1610of the first gear1600is disposed in the first groove1410. The first groove1410is formed to be concave on the outer circumferential surface of the first part1400A. Here, an inlet of the first groove1410may be disposed at the third part1400C.

The first groove1410may be provided as a plurality of first grooves1410. The plurality of first grooves1410may be disposed at predetermined intervals in the outer circumferential surface of the first part1400A in the circumferential direction of the shaft1400. Also, the first part1400A may include a protruding portion1430. The protruding portion1430protrudes from an inner circumferential surface of the first part1400A, corresponding to the first groove1410. The protruding portion1430may be formed due to formation of the first groove1410. For example, the protruding portion1430may be formed as the outer circumferential surface of the first part1400A is pressed to form the first groove1410.

The first part1400A includes a second protrusion1420. The second protrusion1420is disposed to extend from an upper end of the first part1400A toward the outside of the first part1400A. The second protrusion1420may be provided as a plurality of second protrusions1420. The second protrusion1420may be for improving a coupling force between the shaft1400and the holder1220. In particular, the second protrusion1420has an advantage of preventing slipping that occurs between the shaft1400and the holder1220in a rotational direction of the shaft1400.

FIG.25is a view illustrating the shaft and a holder that are coupled,FIG.26is a plan view illustrating the holder, andFIG.27is an enlarged view of a coupling portion between the shaft and the holder.

Referring toFIGS.25to27, the shaft1400and the holder1220may be integrally injection-molded. The holder1220includes a contact portion1220A. The contact portion1220A is disposed at one end of the holder1220to come in contact with the first part1400A of the shaft1400. The contact portion1220A may include a ring-shaped body1221and a plurality of bridges1222that extend from the body1221. The body1221may be disposed to be spaced apart from the holder1220. The bridge1222connects the body1221and the holder1220. The teeth1211of the stator teeth1210may be disposed between the bridges1222.

Referring toFIG.26, the body1221includes an overlapping region O disposed to overlap the first groove1410in the axial direction. The overlapping region O may be disposed in the axial direction of the first groove1410. The overlapping region O blocks one side of the first groove1410to limit axial movement of the first gear1600disposed in the first groove1410. Also, the overlapping region O determines an assembly position of the first gear1600.

Referring toFIG.27, the second protrusion1420is coupled to the body1221and the bridge1222. The second protrusion1420may be disposed on the body1221and the bridge1222. A second groove1221ain which the second protrusion1420is disposed may be formed in the contact portion1220A. The second groove1221amay be disposed across the body1221and the bridge1222. The shaft1400may include a third protrusion1440. The third protrusion1440may be disposed at an upper end of the shaft1400. The third protrusion1440may be provided as a plurality of third protrusions1440. A third groove1222amay be disposed in the body1221. The third protrusion1440is disposed in the third groove1222a. In particular, the third protrusion1440may be disposed at each of both sides of the first groove1410. This is to reinforce weak coupling between the shaft1400and the holder1220due to a concave space of the first groove1410.

The second protrusion1420and the third protrusion1440increase a contact area between the holder1220and the shaft1400to improve coupling between the holder1220and the shaft1400and prevent slipping between the holder1220and the shaft1400in the rotational direction.

FIG.28is a view illustrating a first gear coupled to the shaft.

Referring toFIG.28, the first protrusion1610of the first gear1600is inserted into the first groove1410of the shaft1400. In the axial direction, a length L3of the first groove1410may be larger than a length L4of the first protrusion1610. The first gear1600may rotate while engaged with the second gear1700and move in the axial direction. The length L3of the first groove1410is formed to be larger than the length L4of the first protrusion1610to secure a movement space for the first gear1600in the axial direction.

FIG.29is a view illustrating a protruding portion of the shaft1400.

Referring toFIG.29, the protruding portion1430is disposed on an inner circumferential surface of the shaft1400. As illustrated inFIG.29A, the protruding portion1430may be disposed in a fourth groove1222bof the body1221. The protruding portion1430may increase the contact area between the holder1220and the shaft1400to improve coupling between the holder1220and the shaft1400and prevent slipping between the holder1220and the shaft1400in the rotational direction.

FIG.30is a lateral cross-sectional view of the sensing device.

Referring toFIG.30, the first housing1510may be disposed at an upper side of the second housing1520.

The first housing1510includes the first opening1511. The second housing1520includes the second opening1521. The shaft1400passes through the first opening1511and the second opening1521. A diameter D4, which is an inner diameter of the second opening1521, may be smaller than a diameter D3, which is an inner diameter of the first opening1511. Also, the outer diameter D1of the first part1400A may be smaller than the diameter D3of the first opening1511and larger than the diameter D4of the second opening1521. The outer diameter D2of the second part1400B may be smaller than the diameter D4of the second opening1521.

An inner circumferential surface of the first opening1511is a sliding surface S1for the first part1400A. The first gear1600is directly coupled to the first part1400A. The outer circumferential surface of the first part1400A is disposed to be adjacent to the inner circumferential surface of the first opening1511. As the shaft1400rotates, the outer circumferential surface of the first part1400A may come in contact with the inner circumferential surface of the first opening1511.

In a case in which the first gear1600is attached to the shaft1400through a component made of plastic that is attached to the shaft1400, the corresponding component made of plastic and the inner circumferential surface of the first opening1511that is made of plastic slide against each other, causing a loud noise to occur. In the case of the motor according to an embodiment, the first gear1600is directly coupled to the shaft1400. Also, since the shaft1400is made of metal and the inner circumferential surface of the first opening1511is made of plastic, and thus the component made of plastic and the inner circumferential surface of the first opening1511that is made of plastic slide against each other, the noise may be significantly reduced.

Meanwhile, an outer circumferential surface of the second part1400B is a sliding surface for an inner circumferential surface of the second opening1521. The outer diameter D2of the second part1400B is smaller than the diameter D4of the second opening1521. Also, the outer circumferential surface of the second part1400B is disposed to be adjacent to the inner circumferential surface of the second opening1521. Also, the second housing1520may include an inclined surface1521a. The third part1400C, which is disposed to be inclined, may come in contact with the inclined surface1521aof the second housing1520. That is, the inner circumferential surface of the second opening1521may include the inclined surface1521acoming in contact with the third part1400C. This is due to the structure in which the outer diameter of the first part is formed to be larger than the outer diameter of the second part, and the inclined surface1521ainduces stable rotation of the shaft1400. Accordingly, the inclined surface1521ais a sliding surface S2for the third part1400C disposed to be inclined.

The present invention has been described above on the basis of embodiments thereof, but those of ordinary skill in the art should understand that various modifications and changes may be made to the present invention within the scope not departing from the idea and area of the present invention stated in the claims below. Also, differences relating to the modifications and changes should be interpreted as falling within the scope of the present invention defined by the attached claims.

DESCRIPTION OF REFERENCE NUMERALS