JP2001056258A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor easily assembleable and allowing reduction of a manufacturing cost. SOLUTION: An interfitting member 3A is installed separately from an output shaft 3, and a recessed part 3b formed on the inner circumference of the interfitting member 3A having plural grooves 3a extended in the axial direction and formed on its circumference and a male stopper 15 installed on the circumference of the output shaft 3 are engaged with each other, to thereby execute positioning in the rotative direction. Hereby, a manufacturing cost can be reduced, and positioning in the rotative direction of the output shaft 3 and the interfitting member 3A can be executed, to facilitate mutual phase setting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor, for example, a torque sensor capable of detecting a steering torque in an electric power steering apparatus.

[0002]

2. Description of the Related Art In an electric power steering apparatus mounted on a vehicle, a torque sensor is provided to detect a steering torque for use in driving control of a motor. As a conventional example of such a torque sensor, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. H8-240492 previously proposed by the present applicant. In the torque sensor disclosed in this publication, the first and second rotating shafts arranged coaxially are connected via a torsion bar, and the cylindrical member made of a conductive and non-magnetic material is connected to the first shaft. The second rotating shaft is integrally formed with the second rotating shaft in a rotating direction so as to surround an outer peripheral surface of the first rotating shaft, and at least an enclosed portion of the first rotating shaft surrounded by the cylindrical member is formed of a magnetic material. A groove extending in the axial direction is formed in the enclosed portion, and the cylindrical member is provided with a window such that the degree of overlap with the groove changes according to a relative rotation position between the first rotation shaft and the cylindrical member. The coil is disposed so as to surround the portion of the cylindrical member where the window is formed, and the torque is detected based on the inductance of the coil. Accurate torque detection can be performed. Size of the effect is obtained that is achieved.

[0003]

When the conventional torque sensor disclosed in the above publication is actually applied to a torque sensor for an electric power steering device, the following problems must be solved. I found it to be.

That is, in the case of such a conventional torque sensor,
The overlapping state between the cylindrical member and the groove is detected by using a coil surrounding the cylindrical member. In a vehicle, a collar constituting a steering lock for preventing theft is provided at an upper end of a steering shaft. When the part is fixed by welding or the like, the inner diameter of the coil must be determined so that the collar part can pass through.

More specifically, when actually assembling the steering system, an intermediate portion of the steering system interposed between the steering wheel and, for example, a rack shaft is assembled in advance, and the intermediate portion is connected to the upper end of the steering shaft. At the beginning, the steering shaft is inserted into the inside from below the housing, and the steering shaft is housed in the column connected to the housing, but the coil for the torque sensor is fixed in the housing before inserting the middle part Therefore, it is necessary to determine the inner diameter of the coil so that a portion and a member having the maximum outer diameter of the steering shaft and its accessories can pass therethrough.

Here, unless the gap between the members is made sufficiently small, the detection accuracy of the sensor cannot be ensured. Therefore, as the inner diameter of the coil increases, the outer diameter of the cylindrical member,
It is necessary to increase the outer diameter of the portion of the rotary member that forms the groove of the rotating shaft surrounded by the cylindrical member.

On the other hand, the rotary shaft constituting the steering system is often formed by cold forging. However, if the outer diameter of the groove forming the rotary shaft must be increased for the above-described reason, The working degree in cold forging increases, and it becomes difficult to form grooves integrally with the rotating shaft by cold forging. In such a case, the grooves must be formed by machining, which increases the cost as compared with the case where the grooves are integrally formed by cold forging.

To solve such a problem, it is conceivable to solve the above-mentioned problem by fitting a cylindrical member having a groove formed on the outer periphery to the rotary shaft. There is a problem that it is difficult to set an appropriate rotation phase of

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide a torque sensor that can be easily assembled and that can reduce manufacturing costs. I have.

[0010]

In order to achieve the above object, a torque sensor according to the present invention is provided between a first and a second rotating shaft which are coaxially arranged and connected via a torsion bar. A torque sensor for detecting a transmitted torque, the torque sensor being adapted to be fitted to the first rotating shaft, the fitting member having a plurality of grooves formed in an outer periphery thereof and extending in an axial direction; The first rotating shaft and the fitting member are provided on the outer periphery of the first rotating shaft and the inner periphery of the fitting member. When the first rotating shaft and the fitting member are fitted to each other, they are engaged with each other to position in the rotational direction. And a cylindrical member attached to the second rotating shaft and extending so as to surround at least a part of the fitting member, wherein the groove and the cylindrical member overlap each other. Is transmitted between the first and second rotation shafts based on It is adapted to detect the torque.

[0011]

According to the torque sensor of the present invention, the first and the second coaxially disposed and connected via the torsion bar.
A torque sensor for detecting a torque transmitted to and from the rotating shaft, wherein the torque sensor is adapted to be fitted to the first rotating shaft, and a plurality of grooves extending in the axial direction are formed on the outer periphery. A fitting member, an outer periphery of the first rotating shaft, and an inner periphery of the fitting member are provided on the inner periphery of the fitting member, and are engaged with each other when the first rotating shaft and the fitting member are fitted. An engagement portion for performing positioning in the rotation direction by fitting, and a cylindrical member attached to the second rotation shaft and extending so as to surround at least a part of the fitting member; The torque transmitted between the first and second rotating shafts is detected based on the state of overlap with the cylindrical member, that is, the first rotating shaft and the fitting member are detected. And a separate member to reduce the manufacturing cost and use the engaging portion Since serial and first rotary shaft allows the positioning of the rotational direction of the fitting member, it is easy to each other phase settings.

Further, the engagement portion has a plurality of projections formed on an outer periphery of the first rotating shaft and extending in an axial direction, and an extension formed on an inner periphery of the fitting member in an axial direction. If the number of the protrusions and the number of the recesses match the number of grooves formed on the outer periphery of the fitting member, the manufacturing of the fitting member is easy. Thus, the manufacturing cost can be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 are views showing an embodiment of the present invention, in which a torque sensor according to the present invention is applied to an electric power steering device of a vehicle, and FIG. It is a longitudinal section showing an important section of a steering system. FIG. 2 shows an input shaft 2 (only at the end) and an output shaft 3
FIG. 3 is a perspective view of a state where the torsion bar 4 is separately disassembled. FIG. 3 is a view of the configuration of FIG. 2 cut along a line III-III and viewed in a direction indicated by an arrow. FIG. 4 shows that the fitting member 3A is
FIG. 3 is a perspective view similar to FIG.

First, the structure of the electric power steering apparatus will be described. A torsion bar 4 is provided in a housing 1 comprising an upper housing 1A and a lower housing 1B.
The input shaft 2 and the output shaft 3 connected via the
And 5b rotatably supported. The input shaft 2, the output shaft 3 and the torsion bar 4 are coaxially arranged, and the upper end side of the torsion bar 4 is spline-coupled to the input shaft 2 to be integrated in the rotation direction. The lower end of the pin 4 is pin-coupled to the output shaft 3 at a position that is deeply inserted into the output shaft 3 and is integrated in the rotation direction.

A lower end of a steering shaft 6 is spline-coupled to an upper end of the input shaft 2 so as to rotate integrally therewith. A steering shaft (not shown) is integrally formed on the upper end of the steering 6. It is attached to rotate. A pinion shaft of a rack and pinion type steering device (not shown) is coupled to the lower end of the output shaft 3 so as to rotate integrally. Therefore, the steering force generated by the driver steering the steering wheel is transmitted to steered wheels (not shown) via the steering shaft 6, the input shaft 2, the torsion bar 4, the output shaft 3 and the rack and pinion type steering device. It is supposed to be.

Further, a worm wheel 7 that rotates coaxially and integrally with the output shaft 3 is fitted around the output shaft 3, and a resin engagement portion 7 a of the worm wheel 7 and an outer periphery of the output shaft 8 a of the electric motor 8 are provided. The worm 8b formed on the surface is engaged. Therefore, the torque of the electric motor 8 is transmitted to the output shaft 3 via the output shaft 8a, the worm 8b, and the worm wheel 7, and the torque and the rotation direction of the electric motor 8 are appropriately controlled. By doing
An appropriate steering assist torque can be applied to the output shaft 3.

The lower end of the steering shaft 6 is fixed to the upper housing 1A, and
The steering shaft 6 is accommodated in a steering column 9 fixed to a vehicle body (not shown) via a. A portion of the steering shaft 6 accommodated in the steering column 9 is used to absorb energy at the time of a vehicle collision. Energy absorbing part 6
A is formed, and a lock collar 6B constituting a steering lock for theft prevention is fixed. Since the specific configuration of the steering lock is not the gist of the present invention, a detailed description thereof will be omitted. For example, the configuration disclosed in Japanese Patent Application Laid-Open No. 8-295202 previously proposed by the present applicant is applied. It is possible.

Further, as shown in FIG. 1 and FIG. 2, an output shaft 3 is provided on an outer peripheral surface of a portion of the output shaft 3 close to the input shaft 2.
A thin cylindrical member 10 is disposed so as to surround the fitting member 3A formed of a magnetic material such as iron and the like.

That is, the cylindrical member 10 is formed of a conductive and non-magnetic material (for example, aluminum), and the upper end thereof is fixed to the outer peripheral surface of the input shaft 2 on the output shaft 3 side.

More specifically, a large diameter portion 2A is formed at the end of the input shaft 2 on the output shaft 3 side, and a plurality of axially extending portions (in this example) are formed on the outer peripheral surface of the large diameter portion 2A. In FIG. 2, four axial grooves 11 (two grooves located on the back side are not shown in FIG. 2) and a circumferential groove 12 continuous in the circumferential direction are formed.

The axial grooves 11 are formed at equal intervals (90 degrees in this example) in the circumferential direction and are formed between the upper and lower ends of the large-diameter portion 2A. It is formed near the position where the upper end of the cylindrical member 10 is located when the member 10 is fixed.

On the other hand, on the inner peripheral surface of the cylindrical member 10, a plurality (in this example, 4
) Are formed. The number and formation positions of these protrusions 13 correspond to the axial grooves 11 of the input shaft 2, and therefore, the protrusions 13 are equally spaced from each other in the circumferential direction (90 degrees in this example). The protrusion 13
Is about the same as the depth of the axial groove 11.

When the cylindrical member 10 is fixed to the large-diameter portion 2A, the projection 13 is fitted into the axial groove 11 to position the cylindrical member 10 in the circumferential direction with respect to the input shaft 2, and then the cylindrical member 10 is fixed. The member 10 is pushed in, and its end is brought close to the circumferential groove 12, and in this state, the end of the cylindrical member 10 is caulked inward to bite into the circumferential groove 12. That is, the circumferential position of the cylindrical member 10 with respect to the input shaft 2 is fixed by engaging the protrusion 13 with the axial groove 11,
The axial position of the cylindrical member 10 with respect to the input shaft 2 is fixed by its end biting into the circumferential groove 12.

A spline hole 2 for spline connection with the torsion bar 4 is provided at an end of the input shaft 2 on the output shaft 3 side.
B (FIG. 1) is formed coaxially, and a female stopper 14 is formed on the inner peripheral surface on the end face side of the spline hole 2B as shown in FIG. The female stopper 14 is, for example, a cross-shaped hole composed of four concave portions whose inner peripheral surfaces are concave outward in the radial direction.

A male stopper 15 is formed at the end of the output shaft 3 corresponding to the female stopper 14. The male stopper 15 is, for example, a cross-shaped shaft having four convex portions whose outer peripheral surfaces protrude radially outward, and the circumferential width of each convex portion is slightly larger than the circumferential width of the concave portion of the female stopper 14. The input shaft 2
In addition, the relative rotation between the output shaft 3 and the output shaft 3 is regulated within a predetermined angle range (about ± 5 degrees). In addition, male stopper 1
5 is formed to be longer than the entire length of the fitting member 3A, and when the fitting member 3A is fitted as described later, the upper end of the male stopper 15 projects, as shown in FIG. Then, the projecting portion is included in the female stopper 14.

On the other hand, with the cylindrical member 10 assembled,
In a portion surrounding the fitting member 3A, a plurality of rectangular windows 10a are formed at regular intervals in the circumferential direction on the side close to the protrusion 13, and the windows 10a,.
A plurality of rectangular windows 10b are formed at regular intervals in the circumferential direction so as to be 180 ° out of phase with 10a.

On the other hand, on the outer periphery of the fitting member 3A, a plurality of grooves 3a extending in the axial direction are formed at equal intervals.
However, the number of grooves 3a is the same as the number of each of the windows 10a and 10b. On the other hand, concave portions 3b formed at equal intervals in the circumferential direction are formed on the inner periphery of the fitting member 3A so as to correspond to the male stoppers 15. The male stopper 15 and the recess 3b form an engaging portion.

That is, in the present embodiment, FIG.
As shown in (1), by engaging the fitting member 3A with the male stopper 15, the fitting member 3A is positioned in the rotational direction with respect to the output shaft 3, and integrally rotates.

Here, when no relative rotation occurs between the input shaft 2 and the output shaft 3 (the steering torque is zero), the female stopper 14 formed on the input shaft 2 and the female stopper 14 formed on the output shaft 3. It is sufficient that the male stopper 15 and the male stopper 15 are combined at the neutral position. Therefore, the circumferential position of each concave part of the female stopper 14 is used as a reference when considering the phase of each part of the input shaft 2, and the peripheral position of each convex part of the male stopper 14 is determined. The direction position is used as a reference when considering the phase of each part of the output shaft 3.

The input shaft 2 may be determined based on the circumferential positions of the axial grooves 11,..., 11 formed on the outer peripheral surface of the large-diameter portion 2A and the concave portion of the female stopper 14. Positioning may be performed when the shaft 2 is processed. further,
Regarding the cylindrical member 10, each of the windows 10a,.
a, 10b,..., 10b in the circumferential direction
May be determined on the basis of.

On the other hand, the concave portion 3
When the fitting member 3A is press-fitted into the output shaft 3 in such a manner that the engagement member 3A is engaged with the output shaft 3, the fitting member 3A is positioned in the rotation direction with respect to the output shaft 3, and rotates integrally. If the positional relationship between the concave portion 3b and the groove 3a is appropriately determined at the time of manufacturing the member 3A, the problem of phase shift does not occur. Therefore, according to the present embodiment, the width of each groove 2a is set in a state where relative rotation does not occur between the input shaft 2 and the output shaft 3 (a state where the steering torque is zero) only by assembling the respective members. The center of the direction and the center of the width direction of the window 10a are positioned so as to have a phase of 90 degrees, and the center of the width direction of each groove 2a and the center of the width direction of the window 10b are 90 degrees in the opposite direction. It is located at.

The fitting member 3A can integrally form the recess 3b on the inner periphery and the groove 3a on the outer periphery by cold forging.

Returning to FIG. 1, inside the upper housing 1A, a yoke made of a magnetic material for supporting a bobbin around which coils 20A and 20B of the same standard are wound so as to surround the cylindrical member 10 on the inner peripheral side. 20 is fixed.
However, the coils 20A and 20B are coaxial with the cylindrical member 10, and one coil 20A is connected to the window 1 of the cylindrical member 10.
, 10a are formed, and the other coil 20B is connected to the windows 10b,.
10b surrounds the formed portion.

The inner diameters of the coils 20A and 20B are slightly larger than the outer diameter of the lock collar 6B. The steering column 9 is connected to the upper housing 1A, and the steering shaft 6, the input shaft 2, the torsion bar 4,
This is so that the lock collar 6B can pass through the inside of the coils 20A and 20B when the intermediate portion of the steering system in which the output shaft 3 and the fitting member 3A are integrated is inserted from the steering shaft 6 side.

The ends 20a of the coils 20A and 20B are
It is connected to a substrate 22 housed in a sensor case 21 formed in the upper housing 1A, and a motor control circuit (not shown) is formed on the substrate 22. Since the specific configuration of the motor control circuit is not the gist of the present invention, it will not be described in detail.
As disclosed in Japanese Patent Application Laid-Open No. 0491, an oscillating unit for supplying an alternating current of a predetermined frequency to the coils 20A and 20B, a first rectifying and smoothing circuit for rectifying and smoothing the self-induced electromotive force of the coil 20A, A second rectifying and smoothing circuit for rectifying and smoothing the self-induced electromotive force of 20B, and outputting the rectified and smoothed electromotive force;
A differential amplifier for amplifying and outputting the difference between the outputs of the second rectifying and smoothing circuit, a noise removing filter for removing high-frequency noise from the output of the differential amplifier, and an input shaft 2 and a cylindrical member based on the output of the noise removing filter A torque calculating unit for calculating the direction and magnitude of the relative rotational displacement of 10 and multiplying the result by, for example, a predetermined proportional constant to obtain a steering torque generated in the steering system; and performing steering based on the calculation result of the torque calculating unit. And a motor drive unit that supplies a drive current to the electric motor 8 such that a steering assist torque for reducing the torque is generated.

Next, the operation of this embodiment will be described.
Now, assuming that the steering system is in a straight running state and the steering torque is zero, no relative rotation occurs between the input shaft 2 and the output shaft 3. Therefore, no relative rotation occurs between the input shaft 2 and the cylindrical member 11.

On the other hand, when the steering wheel is steered to generate a torque on the input shaft 2, the torque is transmitted to the output shaft 3 via the torsion bar 4. At this time, a resistance force corresponding to a frictional force between the steered wheels and the road surface and a frictional force such as meshing of gears of the rack and pinion type steering device is generated on the output shaft 3. When the torsion bar 4 is twisted, relative rotation occurs in which the output shaft 3 is delayed, and relative rotation also occurs between the cylindrical member 10 and the output shaft 3. The direction and amount of the relative rotation are determined according to the steering direction of the steering wheel and the generated steering torque.

When relative rotation occurs between the cylindrical member 10 and the input shaft 2, the groove 3a and the windows 10a,.
, 10b change from the initial state, and the grooves 10a,..., 10a and the grooves 10b,.
, 10b are set as described above, the degree of overlap between the groove 3a and the windows 10a,..., 10a and the degree of overlap between the groove 3a and the windows 10b,. Changes in opposite directions.

As a result, the self-inductance of the coil 20A and the self-inductance of the coil 20B change in opposite directions according to the relative rotation between the input shaft 2 and the cylindrical member 10, so that the coils 20A and 20B The self-induced electromotive force also changes in opposite directions. Therefore, when the difference between the self-induced electromotive forces of the coils 20A and 20B is obtained, the difference linearly changes according to the direction and the magnitude of the steering torque. On the other hand, a change in self-inductance due to temperature or the like is canceled in the differential amplifier in the motor control circuit.

Further, a torque calculation section in the motor control circuit obtains a steering torque based on the output of the differential amplifier, and a motor drive section outputs a drive current corresponding to the direction and magnitude of the steering torque to the electric motor 8. To supply. Then, a rotational force corresponding to the direction and magnitude of the steering torque generated in the steering system is generated in the electric motor, and the rotational force is transmitted to the output shaft 3 via the worm 8 b and the worm wheel 7. This means that the steering assist torque has been applied to the output shaft 3, so that the steering torque is reduced and the burden on the driver is reduced.

In this embodiment, a plurality of axial grooves 11 and a circumferential groove 12 are formed at the end of the output shaft 3, and the projection 13 of the cylindrical member 10 is fitted into the axial groove 11. Since the end of the cylindrical member 10 is swaged into the circumferential groove 12, the iron output shaft 3 and the aluminum cylindrical member 10
Even if the members are made of different materials, the holding force does not decrease due to the difference in the coefficient of thermal expansion.
For this reason, the possibility that the relative circumferential position and the axial position of the cylindrical member 10 with respect to the output shaft 3 deviate from the initial state, and that the possibility of being included in the torque detection value can be greatly reduced. Therefore, it is extremely suitable as a torque sensor for an electric power steering device requiring high reliability from the viewpoint of safety.

Further, in this embodiment, the fitting member 3A having the grooves 3a,..., 3a integrally formed on the outer periphery by cold forging and the concave portions 3b integrally formed on the inner periphery is output. Since the male stopper 15 at the end of the shaft 3 is fitted, the coil 20 is adjusted to the outer diameter of the lock collar 6B.
Even if the inner diameters of A and 20B are increased, the grooves 3a requiring high dimensional accuracy can be formed by cold forging without any particular problem, and the same accuracy can be obtained while avoiding the complicated phase adjustment. There is an advantage that the manufacturing cost can be reduced as compared with the case where it is achieved by machining. In addition, the output shaft 3 and the fitting member 3A are tightly engaged with the male stopper 1
Since the positioning is performed in the rotating direction by the concave portion 5 and the concave portion 3b, the position adjustment is unnecessary, and the labor at the time of manufacturing is saved.

If the output shaft 3 and the fitting member 3A are to be integrally formed, the ferromagnetic and corrosion resistance as a sensor and the
In order to satisfy the strength of the steering shaft, it was necessary to use an expensive martensitic stainless steel and heat-treat it. However, according to the present embodiment, the output shaft 3 has only the strength of the steering shaft. Is satisfied, the strength can be secured by work hardening by cold forging without using heat treatment, and the production cost can be further reduced. Also, since the fitting member 3A does not require strength,
It can be formed using a material having good magnetic properties, and the detection sensitivity can be improved.

Here, in the present embodiment, the input shaft 2 corresponds to the second rotating shaft, and the output shaft 3 corresponds to the first rotating shaft. In the above embodiment, the case where the torque sensor according to the present invention is applied to an electric power steering device for a vehicle has been described. However, the present invention is not limited to this. However, the present invention can naturally be applied.

In the above embodiment, the fitting member 3A
Is formed by cold forging, but is not limited thereto, and the fitting member 3A may be formed by sintering, for example.

FIGS. 5 and 6 show a second embodiment of the present invention. FIG. 5A is a perspective view showing a state before the fitting member 103A and the output shaft 103 are assembled. FIG. 5B is a perspective view showing a state after the fitting member 103A and the output shaft 103 are assembled, and FIG. 6 is a view showing an engagement state between the male stopper 115 and the female stopper 114.
It is sectional drawing similar to.

The second embodiment differs from the above-described embodiment in the shapes of the male stopper 115 and the recess 103b. That is, in the above-described embodiment, the male stopper has a cross shape, but in the present embodiment,
The male stopper 115 is formed from eight protrusions that are equally spaced in the circumferential direction. Correspondingly, eight concave portions 103b of the fitting member 103A are also formed at equal intervals in the circumferential direction in accordance with the male stopper 115.

In the present embodiment, there is an advantage that the manufacturing cost can be reduced as compared with a case where the same accuracy is achieved by machining while the complexity of the phase adjustment is avoided, and the present invention is applicable to the female stopper 114. Male stopper 1 in contact
Since the number of the fifteen projections is twice as large as that of the embodiment shown in FIGS. 1 to 4, even if the contact area is reduced, the same strength can be obtained. Therefore, since the protrusion amount of the male stopper 115 can be reduced by that amount, the reduction rate of the cross section in the case where the output shaft 3 is cold forged becomes small, the processing becomes easy, and the life of the cold forging die can be extended. This contributes to a reduction in manufacturing cost.

Further, in the fitting member 103A, since there are eight grooves 103a on the outer periphery, the recesses 103 on the inner periphery are formed.
b and the groove 103a on the outer periphery are alternately shifted,
It can be a member of substantially the same thickness over the entire circumference,
Since there is no uneven thickness, molding is easy, and in some cases, the fitting member 103A can be formed at low cost by molding, for example, a circular tube. In addition, there is an advantage that the phase accuracy between the concave portion 10b on the inner periphery and the groove 103a on the outer periphery is also improved.

FIGS. 7 and 8 are views showing a third embodiment of the present invention. FIG. 7A is a perspective view showing a state before the fitting member 203A and the output shaft 203 are assembled. FIG. 7B is a perspective view showing a state after the fitting member 203A and the output shaft 203 are assembled, and FIG. 8 is a view showing an engagement state between the male stopper 215 and the female stopper 214.
It is sectional drawing similar to.

The third embodiment is different from the second embodiment in that the number of protrusions of the male stopper 215 is 16, and the number of grooves 203a on the outer periphery of the fitting member 103A is also one.
This is the point of six.

In the present embodiment, in addition to the advantages of the above-described embodiment, the number of protrusions of the male stopper 215 abutting on the female stopper 214 is further increased, so that a high strength at the time of abutting the stopper can be secured. Also, the detection sensitivity of the sensor can be increased.

As described above, the present invention has been described in detail with reference to the embodiments. However, the present invention should not be construed as being limited to the above embodiments, and may be appropriately changed and modified without departing from the spirit of the present invention. Of course, it can be improved. For example, a protrusion may be provided on the inside of the fitting member, a groove may be provided on the outer periphery of the output shaft, and the two may be engaged to position the fitting member and the output shaft in the rotational direction.

[0054]

According to the torque sensor of the present invention, the torque sensor detects the torque transmitted between the first and second rotating shafts coaxially arranged and connected via the torsion bar. A fitting member adapted to be fitted to the first rotating shaft and having a plurality of grooves formed in an outer periphery thereof and extending in an axial direction; an outer periphery of the first rotating shaft; An engagement portion provided on an inner periphery of the joining member, the engagement portion performing positioning in the rotation direction by engaging with each other when the first rotating shaft and the fitting member are fitted; A cylindrical member that is attached to the rotating shaft and extends so as to surround at least a part of the fitting member. Based on an overlapping state of the groove and the cylindrical member, the first and the second It detects the torque transmitted between the two rotating shafts That is, while reducing the manufacturing cost by using the first rotating shaft and the fitting member as separate members, and positioning the first rotating shaft and the fitting member in the rotating direction using the engaging portion. Therefore, the mutual phase setting is easy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a steering system according to an embodiment.

FIG. 2 is a perspective view of a state in which an input shaft 2 (only an end portion), an output shaft 3, and a torsion bar 4 are separately disassembled.

FIG. 3 is a view of the configuration of FIG. 2 cut along a line III-III and viewed in a direction of an arrow.

FIG. 4 is a perspective view similar to FIG. 2, showing a state in which a fitting member 3A is fitted to the output shaft 3.

FIG. 5 is a diagram showing a second embodiment, and FIG.
FIG. 5B is a perspective view showing a state before the fitting member 103A and the output shaft 103 are assembled, and FIG.
It is a perspective view showing the state after 3A and output shaft 103 are assembled.

FIG. 6 is a sectional view similar to FIG. 3, showing an engagement state between a male stopper 115 and a female stopper 114.

FIG. 7 is a diagram showing a third embodiment, and FIG.
FIG. 7B is a perspective view showing a state before the fitting member 203A and the output shaft 203 are assembled, and FIG.
It is a perspective view which shows the state after assembling of 3A and the output shaft 203.

FIG. 8 is a sectional view similar to FIG. 3, showing an engagement state between a male stopper 215 and a female stopper 214.

[Explanation of symbols]

 Reference Signs List 1 housing 2 input shaft (first rotation shaft) 2A large diameter portion 3 output shaft (second rotation shaft) 3A, 103A, 203A fitting member 3a, 103a, 203a groove 3b, 103b, 203b recess 4 torsion bar 10 Cylindrical member 14, 114, 214 Female stopper 15, 115, 215 Male stopper

Claims (2)

[Claims] 1. A torque sensor for detecting torque transmitted between first and second rotating shafts disposed coaxially and connected via a torsion bar, wherein the first rotating shaft is provided. A fitting member having a plurality of grooves extending in the axial direction on an outer periphery thereof; an outer periphery of the first rotating shaft; and an inner periphery of the fitting member. An engagement portion that engages with each other to perform positioning in the rotation direction when the first rotation shaft and the fitting member are fitted to each other; And a cylindrical member extending so as to surround at least a part of the joining member. The cylindrical member is transmitted between the first and second rotation shafts based on an overlapping state of the groove and the cylindrical member. A torque sensor adapted to detect the torque of the motor. 2. The engagement portion includes a plurality of projections formed on an outer periphery of the first rotation shaft and extending in an axial direction, and an extension formed on an inner periphery of the fitting member in an axial direction. 2. The torque sensor according to claim 1, wherein the number of the protrusions and the number of the recesses are equal to the number of grooves formed on the outer periphery of the fitting member. 3.