Stator assembly and torque measuring device

Disclosed are a stator assembly and a torque assembly device. The stator assembly includes a stator holder, a first stator which includes a first body making contact with an upper end of the stator holder and a plurality of first teeth extending from the first body so as to be disposed inside the stator holder, a second stator which includes a second body making contact with a lower end of the stator holder and a plurality of second teeth extending from the second body so to be alternately aligned with the first teeth inside the stator holder, and a fusion-welded material that is fusion-welded to the stator holder and the first and second bodies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage application of International Patent Application No. PCT/KR2008/005352, filed Sep. 10, 2008, which claims priority to Korean Application No. 20-2007-0015057, filed Sep. 10, 2007, the disclosures of each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present embodiment relates to a stator assembly and a torque measuring device.

BACKGROUND ART

Since great frictional resistance is applied to a front wheel serving as a steering wheel, a power steering system provides assistant steering force to allow a driver to smoothly manipulate a steering handle. The assistant steering force is determined by measuring torque applied to a torsion bar when the steering handle is steered.

In order to measure torque of the steering wheel, various torque measuring devices have been developed and used. Among them, a torque measuring device employing a magnetic field has been mainly used since it has advantages in terms of a number of parts and price.

In the torque measuring device employing the magnetic field, a magnet is coupled to a steering handle that is an input shaft, one side of a stator holder fixing a stator is coupled to the input shaft through the torsion bar, and the other side of the stator holder is coupled to an output shaft of a front wheel.

Accordingly, when rotating the steering handle by applying external force to the steering handle, torque is measured by detecting a magnetic field according to a difference between a rotational angle of the magnet coupled to the input shaft and a rotational angle of the stator coupled to the stator holder to rotate together with the output shaft. The assistant steering force is determined based on the measured torque and a motor is driven according to the assistant steering force.

DISCLOSURE OF INVENTION

Technical Problem

The embodiment provides a stator assembly and a torque measuring device.

The embodiment also provides a stator assembly, in which a stator can be strongly coupled to a stator holder, and a torque measuring device employing the stator assembly.

The embodiment provides a stator assembly, in which a stator can be easily coupled to a stator holder, and a torque measuring device employing the stator assembly.

Technical Solution

According to the embodiment, a stator assembly includes a stator holder, a first stator which includes a first body making contact with an upper end of the stator holder and a plurality of first teeth extending from the first body so as to be disposed inside the stator holder, a second stator which includes a second body making contact with a lower end of the stator holder and a plurality of second teeth extending from the second body so to be alternately aligned with the first teeth inside the stator holder, and a fusion-welded material that is fusion-welded to the stator holder and the first and second bodies.

According to the embodiment, a stator assembly includes a stator holder, a first stator which includes a first body making contact with an upper end of the stator holder, a plurality of first teeth extending from the first body so as to be disposed inside the stator holder, and a first coupling rim extending from the first body so as to be coupled to a first outer portion of the stator holder, and a second stator which includes a second body making contact with a lower end of the stator holder, a plurality of second teeth extending from the second body so to be alternately aligned with the first teeth inside the stator holder, and a second coupling rim extending from the second body so as to be coupled to a second outer portion of the stator holder.

According to the embodiment, a torque measuring device includes a case, a magnet disposed in the case, the magnet being coupled to an input shaft rotated by external force so as to be rotated, a stator assembly disposed in the case to surround the magnet, the stator assembly being coupled to an output shaft connected to the input shaft through a torsion bar so as to be rotated, and a sensor which detects variation of a magnetic field generated between the magnet and the stator assembly. The stator assembly includes a stator holder, a first stator which includes a first body making contact with an upper end of the stator holder and a plurality of first teeth extending from the first body so as to be disposed inside the stator holder, a second stator which includes a second body making contact with a lower end of the stator holder and a plurality of second teeth extending from the second body so as to be alternately aligned with the first teeth inside the stator holder, and a fusion-welded material that is fusion-welded to the stator holder and the first and second bodies.

According to the embodiment, a torque measuring device includes a case, a magnet disposed in the case, the magnet being coupled to an input shaft rotated by external force so as to be rotated, a stator assembly disposed in the case to surround the magnet, the stator assembly being coupled to an output shaft connected to the input shaft through a torsion bar so as to be rotated, and a sensor which detects variation of a magnetic field generated between the magnet and the stator assembly. The stator assembly includes a stator holder, a first stator which includes a first body making contact with an upper end of the stator holder, a plurality of first teeth extending from the first body so as to be disposed inside the stator holder, and a first coupling rim extending from the first body so as to be coupled to a first outside of the stator holder, and a second stator which includes a second body making contact with a lower end of the stator holder, a plurality of second teeth extending from the second body so as to be alternately aligned with the first teeth inside the stator holder, and a second coupling rim extending from the second body so as to be coupled to a second outside of the stator holder.

Advantageous Effects

According to the embodiments, a stator assembly and a torque measuring device can be provided.

According to the embodiments, a stator assembly, in which a stator is strongly coupled to a stator holder, and a torque measuring device employing the stator assembly can be provided.

According to the embodiments, a stator assembly, in which a stator is easily coupled to a stator holder, and a torque measuring device employing the stator assembly can be provided.

MODE FOR THE INVENTION

Hereinafter, a stator assembly and a torque measuring device according to embodiments will be described with reference to accompanying drawings.

Hereinafter, details about a stator assembly and a torque measuring device adaptable for a power steering system for a vehicle will be made according to the embodiments.

First Embodiment

FIG. 1is a perspective view showing a stator assembly and a torque measuring device according to a first embodiment.

As shown inFIG. 1, a case110is prepared with a predetermined inner space. The case110includes an upper case111and a lower case115, in which the upper case111is provided at an upper portion of a virtual vertical line, and the lower case115is provided at a lower portion of the virtual vertical line. The upper case111is formed at a central portion thereof with a through hole112, and the lower case110is formed at a central portion thereof with a through hole (not shown) corresponding to the through hole112.

Hereinafter, a surface facing an upper portion of the virtual vertical line will be referred to as a top surface, and a surface facing a lower portion of the virtual vertical line will be referred to as a bottom surface.

A stator holder210having a cylindrical shape is installed on the lower case115, and stators310are coupled to upper and lower ends of the stator holder210.

The stator310is provided at an inside thereof with a magnet120having a ring shape, which has a plurality of polarities radially aligned. The magnet120is provided at an inside thereof with a magnet holder130. The magnet120has an inner circumferential surface coupled with an outer circumferential surface of the magnet holder130having a cylindrical shape, and the outer circumferential surface of the magnet120faces teeth313of the stator310, which will be described later, with a predetermined interval.

An input shaft (not shown), which is a steering shaft penetrating the through hole112of the upper case111, is fitted into the inner circumferential surface of the magnet holder130, and an output shaft (not shown) linked with a front wheel of a vehicle, which is a steering wheel, is fitted into the stator holder210.

In detail, the stator holder210is formed with a connection part211having a ring shape which extends radially inward. The connection part211is formed with an insertion hole212. The output shaft (not shown) linked with the front wheel of the vehicle (which is the steering wheel) is inserted into the insertion hole212while penetrating the through hole of the lower case115. A steering handle is coupled to the input shaft, and the input shaft is coupled to the output shaft through a torsion bar (not shown).

Therefore, when rotating the steering handle by applying an external force to the steering handle, the input shaft is rotated, and the magnet holder130and the magnet120are rotated similarly to the input shaft. Then, the output shaft receives a rotational force of the input shaft through the torsion bar to rotate, and the stator holder210and the stator310rotate similarly to the output shaft.

However, since the output shaft is coupled to the front wheel in the contact with a road, torque occurs in the torsion bar due to frictional resistance between the road and the front wheel. The magnet120rotates at a rotational angle different from that of the stator310due to the torque of the torsion bar, a magnetic field between the magnet120and the stator310varies due to difference between rotational angles of the magnet120and the stator.

The magnetic field generated from the magnet120and the stator310is detected by a sensor140supported on a circuit board141of the lower case115. Accordingly, a controller (not shown) receives the intensity of the magnetic field detected by the sensor140and compares the received intensity of the magnetic field with a preset value to measure the torque. Then, the controller determines assistant steering force required to steer a vehicle based on the measured torque and drive a motor to provide the assistant steering force.

A reference number150which is not described represents a collector to concentrate a magnetic field such that the sensor140can effectively detect the intensity of the magnetic field.

Meanwhile, in order to exactly measure a magnetic field, the stator310coupled to the stator holder210must not move on the stator holder210.

In the torque measuring device according to the present embodiment, the stator310is directly coupled to the stator holder210with solidity. This will described later with reference toFIGS. 1 and 2.FIG. 2is a perspective view showing the stator310and the stator holder210shown inFIG. 1.

As shown inFIG. 2, the stator holder210has a cylindrical shape, and is provided at a lower end thereof with the connection part211and the insertion hole212. The output shaft is inserted into the insertion hole212.

The stators310include bodies311having a ring shape and a plurality of teeth313which are bent from the inner circumferential surface of the bodies311and spaced apart from each other by a predetermined interval. The bodies311of the stators310make contact with upper and lower ends of the stator holder210. The teeth313are provided into the stator holder210to make contact with an inner circumferential surface of the stator holder210.

The teeth313of the stator310coupled to an upper portion of the stator holder210are alternately aligned with the teeth313of the stator310coupled to a lower portion of the stator holder210.

The teeth313of the stator310coupled to the lower portion of the stator holder210penetrate a communication hole211aformed in the connection part211such that the teeth313are provided inside the stator holder210. The teeth313face the outer circumferential surface of the magnet120.

In order to couple the stator310to the stator holder210, a plurality of protrusions213that can be fusion-welded by heat or an ultrasonic wave are formed on the upper and lower ends of the stator holder210with a predetermined interval. The protrusion213makes contact with both side surface of each tooth313of the stator310. In detail, after inserting the stator310into the stator holder210such that the protrusion213makes contact with both side surface of each tooth313of the stator310, the protrusion213is fused by heat or an ultrasonic wave. Accordingly, since a portion of the fused protrusion213covers the tooth313, the stator310is strongly fusion-welded to the stator holder210.

A plurality of partition grooves215are formed on the inner circumferential surface of the stator holder210to guide the teeth313such that the teeth313are provided with a predetermined interval. In contrast, protrusion guides (not shown) may be formed on the inner circumferential surface of the stator holder210instead of the partition grooves215.

Second Embodiment to Seven Embodiment

FIGS. 3 to 8are perspective views showing stators and stator holders of stator assemblies according to second to seventh embodiments. Hereinafter, only difference between the first embodiment and the second to seventh embodiments will be described in order to avoid redundancy.

As shown inFIG. 3, in a torque measuring device according to the second embodiment, stators320have bodies321formed thereon with coupling holes321a, and a stator holder220is formed on upper and lower ends thereof with a plurality of protrusions223which are inserted into the coupling holes321aand fused by heat or a ultrasonic wave. The protrusions223are fused by heat or an ultrasonic wave, and a fused portion of the protrusions223cover the body321so that the body321is fusion-welded to the stator holder220.

As shown inFIG. 4, in a torque measuring device according to the third embodiment, protrusion parts230aprotrude from outer peripheral surfaces of upper and lower ends of a stator holder230.

The protrusion230ahas a ring shape. The protrusion230aincludes the same material as that of the stator holder230, and is integrally formed with the stator holder230. In other words, the protrusion part230ais injection-molded together with the stator holder230when the stator holder230is injection-molded.

Bodies331of stators330are mounted on the upper and lower ends of the stator holder230, and an outer circumferential surface of the body331of the stator330makes contact with an inner circumferential surface of the protrusion part230a.In addition, the protrusion part230ahas a height greater than thickness of the body331of the stator330.

Heat or an ultrasonic wave is applied to the protrusion part230asuch that the protrusion part230ais fused. Accordingly, a fused portion of the protrusion part230acovers the body321of the stator330so that the body321is fusion-welded with the stator holder220.

As shown inFIG. 5, a torque measuring device according to the fourth embodiment includes stators340, bodies341making contact with upper and lower ends of a stator holder240, a plurality of teeth343bent from an inner circumferential surface of each body341, and a coupling rim345bent from an outer circumferential surface of the body341to face an outer circumferential surface of the stator holder240. The coupling rim345includes a plurality of caulking parts345aso that the coupling rim345is coupled to the outer circumferential surface of the stator holder240. Accordingly, the stator340is strongly coupled to the stator holder240.

As shown inFIG. 6, in a torque measuring device according to the fifth embodiment, a stator holder250includes protrusion rims255formed on outer peripheral surfaces of upper and lower ends of the stator holder250.

Similarly to the stator340according to the fourth embodiment, stators350include bodies351, teeth353, and coupling rims355. The bodies351make contact with the protrusion rims255as well as the upper and lower ends of the stator holder250. In addition, the coupling rim355faces an outer circumferential surface of the protrusion rim255, and includes a plurality of caulking parts355ato couple to the protrusion rim255.

In this case, the coupling rim355has a width larger than a thickness of the protrusion rim255.

As shown inFIG. 7, a torque measuring device according to the six embodiment includes a stator holder260having the same structure as that of the stator holder250according to the fifth embodiment.

Stators360include bodies361, which make contact with protrusion rims265, as well as upper and lower ends of the stator holder260, a plurality of teeth363bent from an inner circumferential surface of each body361, and a plurality of coupling protrusions367protruding from an outer peripheral surface of the bodies361. The coupling protrusion367is bent to couple to the protrusion rim265, so that the stator360is coupled to the stator holder260.

In this case, the coupling protrusion367may be formed by partially dividing the coupling rim345shown inFIG. 5along an outer circumference of the body341.

As shown inFIG. 8, in a torque measuring device according to the seventh embodiment, a stator holder270has a cylindrical shape, and stators370have bodies371fixed onto upper and lower ends of the stator holder270by an adhesive.

In addition, in a torque measuring device according to another embodiment, the stator370having a shape according to the seventh embodiment may be integrally formed with the stator holder270when injection-molding the stator holder270.

As described above, in the torque measuring device according to the embodiments, a stator is directly coupled to a stator holder by a protrusion of the fusion-welded stator, a portion of the fusion-welded stator holder, a caulked portion of the stator, or a bent portion of the stator. Accordingly, an additional part to couple the stator to the stator holder is not required, so that the manufacturing cost is reduced.

INDUSTRIAL APPLICABILITY

The present invention is adaptable for a torque measuring device.