JPH0675018B2 - Torque sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a torque sensor applied to a telegram power steering device of an automobile, for example.

[Conventional technology]

An electric power steering device is being developed as a power steering device for assisting a force for operating a steering wheel of an automobile. This is configured to detect the torque applied to the steered wheels and rotate the electric motor provided in the steering mechanism according to the detected torque.

By the way, as the torque detecting means, for example, FIG.
A torque sensor shown in FIG. 5 has been proposed (Japanese Utility Model Application No. 63).
-54841). FIG. 4 is a half cross-sectional view showing the structure of the torque sensor. An upper shaft 1a having steering wheels attached thereto and a lower shaft 1c having a steering mechanism attached thereto are coaxially connected via a torsion bar 1b. The upper shaft 1a is rotatably instructed via a bearing 3 to a cylindrical case 2 fixedly attached to a vehicle body (not shown).

A first sleeve 4a made of a non-magnetic material is externally fitted and fixed to the lower end portion (left side in the drawing) of the upper shaft 1a, and first and second cylinders 5 and 6 made of a magnetic material are externally fitted and fixed to the outer circumference thereof. There is. First of these
Between the second cylinders 5 and 6, a non-magnetic material such as brass,
A ring-shaped gap forming member 20 having a narrow width such as aluminum or austenitic stainless steel is interposed and externally fixed to the outer periphery of the first sleeve 4a.

The upper shaft end face of the first cylinder 5 is a plane perpendicular to the shaft center of the upper shaft 1a, and the lower shaft end face has a large number of rectangular tooth portions 5a, 5a ... Formed at equal pitches in the circumferential direction. It is provided. The respective tips of these tooth portions 5a, 5a ... Are surfaces perpendicular to the axis of the upper shaft 1a.

On both shaft end surfaces of the second cylinder 6a, tooth portions 6a, 6a ... And tooth portions 6b, 6b ... Formed at the same pitch and with the same shape as the tooth portions 5a, 5a.
And tooth portions 6a and 6b are aligned on the same line parallel to the axis of the cylinder 6. And tooth 6a and tooth
The cylinders 5 and 6 are positioned so as to face each other at a half of the tooth width of each of the tooth portions 6a and 5a when the torque is not acting on the torsion bar 1b.

A second sleeve made of a non-magnetic material is provided on the upper end of the lower shaft 1a.
4b is externally fitted and fixed, and a third cylinder 7 made of a magnetic material is externally fitted and fixed to the outer periphery thereof. The cylinder 7 has the same shape as the cylinder 5, and is attached with the vertical direction opposite to the cylinder 5.

Therefore, the tooth portions 6b, 6b, ... Of the second cylinder 6 and the tooth portions 7a, 7a, .. When no torque acts on the torsion bar 1b between the tooth portions 6b and 7a, the tooth portions 6b and 7a are in the same facing state as the tooth portions 6a and 5a. The cylinders 6 and 7 are positioned so as to face each other at a half of the width.

On the outer peripheral surface of the lower end portion of the upper shaft 1a, a narrow strip-shaped stopper 8 parallel to the shaft center is provided. On the other hand, lower shaft 1c
On the inner peripheral surface of the opening opened concentrically with the axis at the upper end of
A stopper guide groove 9 having a proper length and a notch is formed in the circumferential direction.

The stopper 8 is engaged in the stopper guide groove 9, and the upper and lower shafts 1a, 1c have an arc shape of the stopper guide groove 9 so that the upper and lower shafts 1a, 1c can rotate relative to each other, for example, by approximately half of the tooth width of the tooth portion 6a. The length is selected.

Inside the case 2, cylindrical bodies 10A and 10B made of a magnetic material and having a circumferential groove are internally fixed. And the cylindrical body 10A is
The first and second cylinders 5 and 6 are opposed to each other, and the cylindrical body 10B is opposed to the second and third cylinders 6 and 7 to be opposed to each other. The first electromagnetic coupling detection coil 11 and the second electromagnetic coupling detection coil 12 are wound around the circumferential grooves of the cylindrical bodies 10A and 10B, respectively, so that the first electromagnetic coupling detection coil 11 is cylindrical. The fifth and sixth electromagnetic coupling detection coils 12 are electromagnetically coupled to the cylinders 6 and 7, respectively.

[Problems to be Solved by the Invention]

However, in the above torque sensor, the tooth portions 6a and 6b are provided on both shaft end surfaces of the second cylinder 6,
In order to form the teeth on both ends of the cylinder as described above, it is difficult to position the teeth on one end and the teeth on the other end, and it is difficult to suppress the variation in the positional deviation between the teeth on both ends and the wing vibration on the other end. There was a problem in manufacturing.

Further, the first, second, and third cylinders 5, 6, and 7 are the upper shaft 1a and the lower shaft 1
Although it is fixed to c by press fitting through non-magnetic sleeves 4a, 4b, this method has a problem that axial positioning of each cylinder 5, 6, 7 cannot be performed.

The present invention has been made in view of the above problems,
By providing four cylinders and forming a tooth portion on one axial end surface of each of these cylinders, one end surface of all the cylinders becomes a smooth surface, which facilitates manufacturing, and thus four cylinders Can be formed in the same shape and can be easily manufactured. In addition, two of the four cylinders adjacent to each other on two sides form independent magnetic circuits, and one magnetic circuit is formed. From one to the other magnetic circuit, the performance can be stable without magnetically affecting the other magnetic circuit.
Positioning in the axial direction is easy by interposing a sleeve having a restricting portion that restricts the movement in the axial direction between the second and third cylinders and the one shaft, and by tightening the sleeve on the one shaft to attach the sleeve. It is an object of the present invention to provide a torque sensor that can be firmly fixed.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is provided with four magnetic cylinders having teeth formed on one shaft end surface.
The first, second, and third cylinders are attached to one of the two shafts connected via a torsion bar so that the teeth of the cylinder and the teeth of the third and fourth cylinders face each other. It is characterized in that the fourth cylinder is attached to the other shaft, and two electromagnetic coupling detection coils that are electromagnetically coupled to the first and second cylinders and the third and fourth cylinders are provided.

In addition, a non-magnetic material having a restricting portion that restricts the axial movement of the second and third cylinders between the inner peripheral surfaces of the second and third cylinders and the outer peripheral surface of the one shaft. The sleeve is inserted.

Further, the sleeve is attached to the outer peripheral portion of one shaft by tightening.

[Action]

According to the present invention, according to the above structure, the first cylinder is fixedly installed on one shaft with the tooth portion thereof being fitted in the direction of the other shaft, and the second cylinder is further fixed to the one shaft portion by the tooth portion. Is inserted so as to face the tooth portion of the first cylinder, and then the third cylinder is inserted into this one shaft, and the tooth portion is inserted in the direction of the other shaft, and is inserted into the other shaft. Secures the fourth cylinder with its teeth facing the one axis and facing the teeth of the third cylinder. Then, two electromagnetic coupling detection coils are arranged so as to surround the first and second cylinders and the third and fourth cylinders, respectively.

The first and second cylinders form one magnetic circuit, and the third and fourth cylinders form another magnetic circuit.

〔Example〕

 The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a schematic front view showing a main part of a torque sensor according to the present invention, and FIG. 2 is a longitudinal sectional view showing a structure of a main part of an electric power steering apparatus for an automobile using the torque sensor,
FIG. 3 is a schematic perspective view of the main part of the torque sensor.

An upper shaft 11A having steering wheels (not shown) and a lower shaft 11C having steering mechanisms (not shown) are coaxially connected via a torsion bar 11B, and the upper shaft 11A is fixed to a vehicle body (not shown). It is rotatably supported via a bearing 26 in a tubular case 25 that has been attached.

The upper shaft 11A has a torsion bar insertion hole 11a that opens in the axial direction at the center in the radial direction, and the outer periphery of the upper shaft 11A has a large diameter on the upper side (right side in the figure) via a stepped portion 11b. Part 1
It is formed in 1d.

Then, in the stepped portion 11b of the upper shaft 11A, the first cylinder 14 made of a magnetic material is in contact with the upper end (the right end in the figure) of the first cylinder 14 against the stepped wall surface of the large diameter portion 11c. It is fitted and fixed by press-fitting, and the reduced diameter part 11d on the lower side (left side in the figure)
The non-magnetic body, the lower end of which is locked to the tapered thin portion 11e provided in the reduced diameter portion 11d by being squeezed, and which is outwardly restricted to one end to regulate the movement. A sleeve 15 having a portion 15a is externally fitted and fixed. On the outer circumference of the sleeve 15, second and third cylinders 16 and 17 made of magnetic material and having the same shape as the first cylinder 14 except for the inner diameter are fixedly fitted. It should be noted that this inner diameter can be designed to have the same size as appropriate, in which case the cylinders will have the same shape. Between the first cylinder 14 and the second cylinder 16 and between the second cylinder 16 and the third cylinder 17, narrow ring-shaped gap forming members 21 and 22 made of a non-magnetic material are interposed. There is.

The upper shaft end face of the first cylinder 14 is formed on a plane perpendicular to the shaft center of the upper shaft 11A, and the lower shaft end face has a large number of rectangular tooth portions 14a, 14a ... Formed at equal pitches in the circumferential direction. It is provided. The respective tip ends of these tooth portions 14a, 14a ... Are formed on a surface perpendicular to the axis of the upper shaft 11A. Similarly, teeth 16 are formed on the upper shaft end surface of the second cylinder 16 and the lower shaft end surface of the third cylinder 17.
a, 16a, and 17a, 17a are provided, and the lower shaft end surface of the second cylinder 16 and the upper shaft end surface of the third cylinder are formed in a plane perpendicular to the shaft center of the upper shaft 11A. Therefore, the first cylinder
The tooth portions 14a, 14a ... Of 14 and the tooth portions 16a, 16a ... of the second cylinder 16 face each other.

A fourth cylinder 18 made of a magnetic material is externally fitted and fixed to the upper end of the lower shaft 11C. This cylinder 18 has the same shape as the first, second, and third cylinders 14, 16, 17 except for the inner diameter, and its tooth portion 18a,
18a opposes the tooth portions 17a, 17a ... Of the third cylinder 17 with a proper distance.

Inside the case 25, cylindrical bodies 19A and 19B made of a magnetic material and having a circumferential groove are internally fixed. The tubular body 19A is arranged so as to face the facing portion of the first cylinder 14 and the second cylinder 16 on the upper side, and the tubular body 19B is arranged on the third cylinder 1 on the lower side.
It is arranged so as to face the facing portion between the seventh cylinder 4 and the fourth cylinder 18. And, in the circumferential grooves of these cylinders 19A, 19B, the first
Electromagnetic coupling detection coil 31, second electromagnetic coupling detection coil 32
Are respectively wound, so that the first electromagnetic coupling detection coil 31 has the first cylinder 14 and the second cylinder 16, and the second electromagnetic coupling detection coil 32 has the third cylinder 17 and the fourth cylinder 16. The cylinders 18 are electrically coupled to each other. At this time, since the second cylinder 16 and the third cylinder 17 are separated, the two magnetic circuits are completely independent, and the magnetic influence from one magnetic circuit to the other magnetic circuit. It has no effect.

Next, the procedure of assembling the torque sensor having the above configuration will be described. The first cylinder 14 is fixed to the stepped portion 11b of the upper shaft 11A by inserting the tooth portion 14a of the toothed portion 14a toward the lower shaft 11C. Then, after inserting the gap forming body 21 into the upper shaft 11A, the second and third cylinders 16 and 17 and the second and third cylinders 16 and 17 are provided on the outer peripheral portion.
A sleeve 15 in which a gap forming body 22 interposed between 17 is fitted
Is externally fitted to the reduced diameter portion 11d of the upper shaft 11A, and the lower end portion thereof is tightly engaged with the tapered small diameter portion 11e so that the sleeve 15 is externally fitted and fixed to the upper shaft 11A.
At this time, the second and third cylinders 16 and 17 are restricted from moving in the axial direction by the protruding restricting portion 15a provided on the sleeve 15. Further, a fourth cylinder 18 is fixedly provided on the upper end of the lower shaft 11C. In the above assembly, the tooth portions 14a and 16a of the first and second cylinders 14 and 16 are opposed to each other, and the third and fourth cylinders 17 and 1 are
The eight tooth portions 17a and 18a are assembled so as to face each other.
Then, the first and second cylinders 14 and 16 and the third and fourth cylinders 17 and 18
The cylindrical bodies 19A and 19B are arranged by winding the electromagnetic coupling detection coils 31 and 32 around the circumferential grooves so as to respectively surround the.

〔The invention's effect〕

As described above in detail, according to the first aspect of the present invention, four magnetic material cylinders are provided, and the tooth portions are formed on the shaft end faces of one of these cylinders. One end surface of the is smooth and easy to manufacture.
Two independent cylinders on each side of each cylinder form independent magnetic circuits, and stable performance without magnetically affecting one magnetic circuit to the other You can Also,
According to the second and third inventions, the sleeve having the restricting portion for restricting the axial movement is provided between the second and third cylinders located at the center among the four cylinders and one shaft. The sleeve is fastened to one of the shafts by tightening it, so that the axial positioning can be facilitated and the fixing can be made firm.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic front view showing an essential part of an embodiment of a torque sensor according to the present invention, and FIG. 2 is an essential part of an electric power steering device for an automobile using the torque sensor. FIG. 3 is a longitudinal sectional view showing the structure of FIG. 3, FIG. 3 is a schematic perspective view of a main portion of the torque sensor, FIG. 4 is a half sectional view of the conventional torque sensor, and FIG. 5 is a schematic perspective view of the conventional torque sensor. Is. 11A ... upper shaft, 11B ... torsion bar, 11C ... lower shaft, 14 ... first cylinder, 14a ... teeth, 15 ... sleeve, 15a ... regulating part, 16 ... second cylinder , 16a …… Tooth part,
17 ... Third cylinder, 17a ... Tooth, 18 ... Fourth cylinder, 1
8a …… Tooth, 31,32 …… Electromagnetic coupling detection coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-292029 (JP, A) JP-A-59-208431 (JP, A) JP-A-61-245033 (JP, A)

Claims (3)

[Claims] 1. A magnetic body comprising four magnetic cylinders having tooth portions formed on one shaft end surface thereof so that the tooth portions of the first, second and third and fourth cylinders face each other. , The first, second, and third cylinders are attached to one of the two shafts connected via a torsion bar, and the fourth cylinder is attached to the other shaft,
A torque sensor comprising two electromagnetically coupled detection coils that are electromagnetically coupled to the first and second cylinders and the third and fourth cylinders, respectively. 2. A restricting portion for restricting axial movement of the second and third cylinders is provided between inner peripheral surfaces of the second and third cylinders and an outer peripheral surface of the one shaft. The torque sensor according to claim 1, wherein a sleeve made of a non-magnetic material is interposed. 3. The torque sensor according to claim 2, wherein the sleeve is fixedly attached to the outer peripheral portion of one shaft.