JP2000346727A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a noncontact torque sensor having simple structure. SOLUTION: This torque sensor has a steering side shaft 2 and a steering mechanism side shaft 3 coupled coaxially through a torsion bar 4 such that they can be rotary displaced relatively. The shafts 2, 3 are secured with magnetic discs 10, 11, respectively. The magnetic discs 10, 11 are inclining against the shafts 2, 3. Reluctance elements 21, 22 are juxtaposed in the direction parallel with the axial direction of the steering side shaft 2 and disposed oppositely to the outer circumferential end face 10a of the magnetic disc 10. Reluctance elements 23, 24 are juxtaposed in the direction parallel with the axial direction of the steering mechanism side shaft 3 and disposed oppositely to the outer circumferential end face 11a of the magnetic disc 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor, and more particularly, to a torque sensor used for an electric power steering device of an automobile.

[0002]

2. Description of the Related Art For example, an electric device has been developed as a power steering device for assisting a force for operating a steering wheel of an automobile. This is a device in which a steering torque of a driver is detected, and an electric motor provided in a steering mechanism generates a steering assist force according to the detected torque.

[0003] As a sensor for detecting the steering torque, a non-contact and simple-structured torque sensor is desirable in terms of reliability and cost. Conventional torque sensors include those that detect with magnetostriction, those that detect with a change in inductance, those that detect with sliding resistance, those that detect with a potentiometer, and the like.

[0004]

However, a torque sensor for detecting a sliding resistance or a potentiometer has a problem that a contact portion such as a slider or a resistor is worn. Further, since the torque sensor is usually arranged near the driver's seat, there is also a problem that a noise generated from a contact portion such as a slider or a resistor gives a driver discomfort. In the case where a structure for converting the torque into the amount of movement of the slider member in the linear direction is employed, there is a problem of durability due to wear of the contact portion due to the presence of the mechanical contact portion.

Further, other conventional torque sensors include:
There is a problem in that there is a machined part that requires dimensional accuracy in a complicated shape, or the number of machined parts is large, so that the torque sensor becomes expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a torque sensor which can detect a torque in a non-contact manner and has a simple structure.

[0007]

In order to achieve the above object, a torque sensor according to the present invention is coaxially connected via a torsion bar, and when a rotational torque is applied to the torsion bar. A torque sensor for detecting the rotational torque in a plurality of shafts that can be relatively rotated and displaced by torsion, the plurality of magnetic plates being fixed to each of the plurality of shafts and changing positions with rotation of the shafts. And a magneto-electric conversion element that is disposed to face the outer peripheral end surfaces of the plurality of magnetic plates and detects a change in position of the plurality of magnetic plates due to rotation of a shaft.

More specifically, a plurality of magnetic plates are inclined with respect to each axis, and at least two magnetoelectric conversion elements are juxtaposed in each magnetic plate in a direction parallel to the axis. . Alternatively, a plurality of magnetic plates are fixed to each axis at a position eccentric from the center, and at least two magnetoelectric conversion elements are arranged at positions symmetrical with respect to the axis for each magnetic plate, and Magnetoelectric conversion elements are connected in series.
Here, the magnetic plate is circular or elliptical.

By arranging the magnetoelectric conversion element opposite to the outer peripheral end surface of the magnetic plate fixed to the rotation axis, the magnetoelectric conversion element is mechanically independent of the rotation axis and is attached to the rotation axis. Non-contact detection of the generated torque.

[0010] When there is no twist between the plurality of shafts, the phase difference between the detection signals output from the magnetoelectric conversion elements facing the end surfaces of the respective magnetic plates remains unchanged. However, when a twist is generated between a plurality of shafts, the relative position of the magnetic plate changes, so that the phase difference between the detection signals shifts substantially in proportion to the twist amount. This difference in phase difference is regarded as a torque amount.

Further, each time the shaft makes one rotation, a detection signal of one cycle or more is output from the magnetoelectric conversion element. The detection signal of two or more cycles may be output during one rotation of the shaft.

Further, a magneto-electric conversion element is further opposed to the outer peripheral end faces of the two magnetic plates so as to output a detection signal having a phase angle different from the detection signal output from the magneto-electric conversion element. By arranging, when it is difficult to detect a phase difference shift of one of the detection signals, the phase difference shift can be detected by using the other detection signal. Thereby, more accurate torque detection is performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a torque sensor according to the present invention will be described below with reference to the accompanying drawings. In each embodiment, the same components and the same portions are denoted by the same reference numerals.

[First Embodiment, FIGS. 1 to 7] FIGS. 1 and 2 show one embodiment of a torque sensor according to the present invention. The torque sensor 1 includes a steering-side shaft 2 having a steering wheel (not shown) attached thereto and a steering-mechanism-side shaft 3 having a steering mechanism not shown attached thereto coaxially and relatively via a torsion bar 4. It is connected so that rotation displacement is possible. These shafts 2 and 3 are rotatably supported by a cylindrical case 5. When a torque is generated between the steering-side shaft 2 and the steering-mechanism-side shaft 3, the torsion bar 4 that is easily elastically deformed is twisted.

A circular magnetic plate 10 is fixed to the steering shaft 2 at the center of the circle. Similarly, the steering mechanism side shaft 3
Has a circular magnetic plate 11 fixed at the center of the circle. The main surfaces of the two magnetic plates 10 and 11 have axes 2 and 2, respectively.
3 (in other words, inclined with respect to the radial direction of the shafts 2 and 3). The magnetic plates 10 and 11 are inclined in opposite directions. When the circular magnetic plates 10 and 11 are inclined, the magnetic plates 10 and 11 become apparently elliptical when viewed from above, and the outer peripheral end surfaces 10a and 11a and the magnetoresistive element 2
The interval between the rotation speeds 1 to 24 (described later) fluctuates, and the accuracy of torque detection decreases. Therefore, elliptical magnetic plates 10 and 11 may be used and the major axes thereof may be inclined so that the magnetic plates 10 and 11 may be devised to have a circular shape.

On the outer peripheral wall of the case 5, torque detecting holes 6 and 7 are juxtaposed in the axial direction of the shafts 2 and 3. The torque detecting hole 6 accommodates the magnetoresistive elements 21 and 22 and the magnet M1 that applies a bias magnetic field to the magnetoresistive elements 21 and 22. The torque detecting hole 7 has the magnetoresistive element 2
3 and 24, and a magnet M2 for applying a bias magnetic field to the magnetoresistive elements 23 and 24 are housed therein. Magnetic resistance element 2
The reference numerals 1 and 22 are juxtaposed in a direction parallel to the axial direction of the steering-side shaft 2 and are arranged so as to face the outer peripheral end face 10 a of the magnetic plate 10. Magnetic resistance elements 23, 24
Are arranged side by side in a direction parallel to the axial direction of the steering mechanism side shaft 3 and are arranged so as to face the outer peripheral end surface 11 a of the magnetic plate 11.

As shown in FIG. 3, the magnetoresistive elements 21 to 2
Reference numeral 4 denotes a substrate 32 and a magnetoresistive pattern 37 provided on an upper surface 32a of the substrate 32 (hereinafter, referred to as a detection surface 32a).
And terminal electrodes 34a and 34b (FIG. 3
Shows the magnetoresistive element 21 as a representative example). The magnetoresistive elements 21 to 24 are made of, for example, InSb, InAs,
After a compound semiconductor such as GaAs is provided as a thin film on the substrate 32 by a bulk method, an evaporation method, a sputtering method, or the like, a metal film such as Al is formed on the surface of the compound semiconductor thin film by a method such as an evaporation method or a sputtering method. It is formed at a predetermined pitch.

Alternatively, the magnetoresistive elements 21 to 24
A metal film such as Al may be formed at a predetermined pitch on the surface of a single crystal semiconductor substrate 32 such as nSb. The semiconductor thin film is made of glass, sapphire,
A single crystal semiconductor substrate may be directly formed on the substrate 32 of alumina, ferrite, silicon, or the like, or a semiconductor thin film or a single crystal semiconductor substrate formed separately may be attached to the substrate 32 with an adhesive. A composite substrate or the like is used. In particular, when a compound semiconductor is formed directly on a sapphire or silicon substrate 32, a compound suitable for a torque sensor of an automobile requiring high temperature resistance can be obtained.

The resistance values of the magnetoresistive elements 21 to 24 increase as the magnetic field increases. Magnetic resistance pattern 37
Is a meandering shape to obtain a predetermined magnetoresistance value, and the ratio W / L of the width W to the length L of the segment of the magnetoresistance pattern 37
To increase the sensitivity. As described above, when semiconductor magnetoresistive elements are used as the magnetoresistive elements 21 to 24, the magnetic plates 10 and 11 and the magnetoresistive elements 21 to 24 are used.
Can be set wider than other magneto-electric conversion elements.

The magnetoresistive elements 21 to 24 are electrically connected as shown in FIG. That is, the magnetoresistive element 21
And 22 are connected in series, and the magnetoresistive elements 23 and 24 are connected in series, and then both are connected to a power supply terminal 41 and a ground terminal 42.
And in parallel. Then, a constant voltage Vd is applied to the power supply terminal 41 to obtain a potential change of the output terminal 43 connected between the magnetoresistive elements 21 and 22 as an output signal S1 and to obtain a potential change between the magnetoresistive elements 23 and 24. A potential change of the connected output terminal 44 is obtained as an output signal S2.

Next, the operation and effect of the torque sensor 1 having the above configuration will be described. As shown in FIG. 1, in the torque sensor 1, when the steering-side shaft 2 is rotated by one rotation in the direction indicated by the arrow K <b> 1, the steering-side shaft 2 is fixed in a state where the magnetic body plate 10 fixed to the steering-side shaft 2 is also inclined. One rotation around the center. At this time, the outer peripheral end face 10a of the magnetic plate 10 is
It is displaced in the direction indicated by arrow K3 with respect to 1 and 22.

When the steering shaft 2 is rotated once, the steering mechanism shaft 3 is also rotated via the torsion bar 4 in the direction indicated by the arrow K2. At the same time, the magnetic body plate 11 fixed to the steering mechanism side shaft 3 also rotates about the steering mechanism side shaft 3 in an inclined state. At this time, the outer peripheral end surface 11a of the magnetic plate 11 is displaced in the direction indicated by the arrow K4 with respect to the magnetoresistive elements 23 and 24. When no torque is generated between the steering shaft 2 and the steering mechanism shaft 3, the relative positions of the magnetic plates 10 and 11 remain unchanged. Therefore, for example, as shown in FIG.
When the outer peripheral end face 10a is opposed to 2, the bias magnetic field generated by the magnet M1 is concentrated on the magnetoresistive element 22, so that the resistance value of the magnetoresistive element 22 is high. Conversely, the magnetoresistive element 2
1 is because the bias magnetic field by the magnet M1 is relaxed.
Resistance value is low.

On the other hand, the outer peripheral end surface 11a of the magnetic plate 11 faces the magnetoresistive element 23, and the bias magnetic field generated by the magnet M2 concentrates on the magnetoresistive element 23, so that the resistance value of the magnetoresistive element 23 is high. Conversely, the resistance value of the magnetoresistive element 24 is low.

When the magnetic plates 10 and 11 rotate, the outer peripheral end faces 10a and 11a separate from the magnetoresistive elements 22 and 23 and approach the magnetoresistive elements 21 and 24. Magnetic plate 10
Is rotated by 180 degrees, is displaced to the position indicated by the dashed line 10 ′, and the outer peripheral end face 10 a ′ faces the magnetoresistive element 21. At this time, since the bias magnetic field generated by the magnet M1 is concentrated on the magnetoresistive element 21, the resistance value of the magnetoresistive element 21 increases. Conversely, the resistance value of the magnetoresistive element 22 is reduced because the bias magnetic field generated by the magnet M1 is reduced. On the other hand, when the magnetic plate 11 is also rotated by 180 degrees, it is displaced to the position indicated by the alternate long and short dash line 11 ′, and the outer peripheral end face 11 a ′ faces the magnetoresistive element 24. Therefore, the magnetoresistive element 2
4, the resistance of the magnetoresistive element 23 decreases.

When the magnetic plates 10 and 11 are further rotated,
The outer peripheral end faces 10a and 11a are separated from the magnetoresistive elements 21 and 24 and approach the magnetoresistive elements 22 and 23. When the magnetic body plate 10 rotates 360 degrees and returns to the original position, the outer peripheral end face 1
0a again faces the magnetoresistive element 22. Therefore, the resistance value of the magnetoresistive element 22 becomes the original high value, and the resistance value of the magnetoresistive element 21 becomes the original low value. On the other hand, the magnetic plate 1
1 also rotates 360 degrees and returns to the original position, the outer peripheral end face 11
a again faces the magnetoresistive element 23. Therefore, the resistance value of the magnetoresistive element 23 becomes the original high value, and the resistance value of the magnetoresistive element 24 becomes the original low value.

Thus, each time the magnetic plates 10 and 11 make one rotation, the output terminals 43 and 44 output sine wave output signals S1 and S2 of one cycle as shown in FIG. Since the magnetic plates 10 and 11 are fixed to the shafts 2 and 3 while being inclined in opposite directions, the output signals S1 and S2 have a phase difference of 180 degrees. For example, the magnetic plates 10 and 11
Is in the position shown in FIG. 1, the output signal S1 is at the upper peak of the sine wave, and the output signal S2 is at the lower peak of the sine wave. The output signals S1 and S2 are used as signals for a control circuit of the electric power steering device.

Here, when torque is generated between the steering shaft 2 and the steering mechanism shaft 3 and the torsion bar 4 is twisted, the relative positions of the magnetic plates 10 and 11 change.
Accordingly, the output signal S2 has an output signal waveform indicated by a dotted line S2 ', and a phase difference occurs between the output signals S1 and S2. The amount of twist of the torsion bar 4 is determined by the output signal S
It is substantially proportional to the difference in phase difference between S1 and S2. Torque sensor 1
Captures the deviation of the phase difference as a torque amount. As described above, in order to measure the amount of twist of the torsion bar 4 in a non-contact manner, the magnetoresistive elements 21 to 24 are disposed on the case 5 mechanically independent of the shafts 2 and 3,
By measuring the torque generated between the two in a non-contact manner, the torque sensor 1 with high durability can be obtained.

As shown in FIG. 6, the magnetic plates 10 and 11 are each tilted in the same direction, and
Alternatively, the torque sensor 1A may be fixed to the steering mechanism side shaft 3. In this case, as shown in FIG. 7, the phase difference between the output signals S1 and S2 is 0 degree. Then, torque is generated between the steering-side shaft 2 and the steering-mechanism-side shaft 3, and the torsion bar 4
When the torsion occurs, the output signal S2 has an output signal waveform indicated by a dotted line S2 ', and a phase difference occurs between the output signals S1 and S2.

[Second Embodiment, FIGS. 8 to 10] FIGS. 8 and 9 show another embodiment of the torque sensor according to the present invention.
Shown in The torque sensor 51 of the second embodiment is fixed to the steering shaft 2 and the steering mechanism shaft 3 at positions where the circular magnetic plates 10 and 11 are eccentric from the center of the circle.
The main surfaces of the two magnetic plates 10 and 11 are perpendicular to the axes 2 and 3.

In the outer peripheral wall portion of the case 55, the torque detecting holes 56,
58 and holes 57 and 59 for torque detection are provided side by side. The torque detecting holes 56 to 59 accommodate magnetoresistive elements 21 to 24 and magnets M1 to M4 for applying a bias magnetic field to the magnetoresistive elements 21 to 24, respectively. The magneto-resistive elements 21 and 22 are provided at positions that are line-symmetric with respect to the steering-side shaft 2, and the outer peripheral end face 10 of the magnetic plate 10.
a. Magnetic resistance element 23
And 24 are provided at positions symmetrical with respect to the steering mechanism side shaft 3 and are arranged so as to face the outer peripheral end surface 11 a of the magnetic plate 11. These magnetoresistive elements 21 to
24 are electrically connected as shown in FIG.

Next, the operation and effect of the torque sensor 51 having the above configuration will be described. As shown in FIG. 8, in the torque sensor 51, when the steering shaft 2 is rotated by one rotation in the direction indicated by the arrow K1, the magnetic plate 10 fixed to the steering shaft 2 is rotated.
Also makes one rotation about the steering shaft 2. At this time, since the magnetic plate 10 is fixed eccentrically to the steering shaft 2, the outer peripheral end surface 10a is displaced in the direction indicated by the arrow K3 with respect to the magnetoresistive elements 21 and 22.

When the steering shaft 2 makes one rotation, the steering mechanism shaft 3 also rotates through the torsion bar 4 in the direction indicated by the arrow K2. At the same time, the magnetic plate 11 fixed to the steering mechanism side shaft 3 also rotates about the steering mechanism side shaft 3. At this time,
Since the magnetic plate 11 is eccentrically fixed to the steering mechanism side shaft 3, the outer peripheral end face 11 a is fixed to the magnetoresistive elements 23, 2.
4 in the direction indicated by arrow K4.

When no twist occurs between the steering shaft 2 and the steering mechanism shaft 3, the relative positions of the magnetic plates 10 and 11 are unchanged. Accordingly, as shown in FIG. 8, for example, the outer peripheral end face 10a is far from the magnetoresistive
, The resistance of the magnetoresistive element 22 is high, and conversely,
The resistance value of the magnetoresistive element 21 is low. On the other hand, the magnetic plate 11
Is far from the magnetoresistive element 23 and close to the magnetoresistive element 24, the resistance of the magnetoresistive element 24 is high and the resistance of the magnetoresistive element 23 is low.

When the magnetic plates 10 and 11 rotate, the outer peripheral end faces 10a and 11a separate from the magnetoresistive elements 22 and 24 and approach the magnetoresistive elements 21 and 23. Magnetic plate 10
Is rotated to the position indicated by the alternate long and short dash line 10 ′ when rotated by 180 degrees, and the outer peripheral end face 10 a ′ is closest to the magnetoresistive element 21 and farthest from the magnetoresistive element 22. Therefore, the resistance value of the magnetoresistive element 21 increases, and conversely, the resistance value of the magnetoresistive element 22 decreases. On the other hand, the magnetic plate 11
Is also rotated by 180 degrees, it is displaced to the position indicated by the alternate long and short dash line 11 ', and the outer peripheral end face 11a' comes closest to the magnetoresistive element 23 and farthest from the magnetoresistive element 24. Therefore,
The resistance of the magnetoresistive element 23 increases, and conversely, the resistance of the magnetoresistive element 24 decreases.

When the magnetic plates 10 and 11 further rotate,
The outer peripheral end faces 10a and 11a are separated from the magnetoresistive elements 21 and 23 and approach the magnetoresistive elements 22 and 24. When the magnetic body plate 10 rotates 360 degrees and returns to the original position, the outer peripheral end face 1
0a comes closest to the magnetoresistive element 22 again. Therefore, the resistance value of the magnetoresistive element 22 becomes the original high value, and the resistance value of the magnetoresistive element 21 becomes the original low value. On the other hand, when the magnetic plate 11 also rotates 360 degrees and returns to the original position, the outer peripheral end face 1
1a comes closest to the magnetoresistive element 24 again. Therefore, the resistance value of the magnetoresistive element 24 becomes the original high value, and the resistance value of the magnetoresistive element 23 becomes the original low value.

Thus, each time the magnetic plates 10 and 11 make one rotation, the torque sensor 51 outputs sinusoidal output signals S1 and S2 of one cycle similar to the graph shown in FIG. Since the magnetic plates 10 and 11 are fixed to the axes 2 and 3 at positions eccentric in the same direction from the center of the circle, the output signals S1 and S2 have a phase difference of 0 degree. The output signals S1 and S2 are used as signals for a control circuit of the electric power steering device.

Here, when a torque is generated between the steering shaft 2 and the steering mechanism shaft 3 and the torsion bar 4 is twisted, the relative positions of the magnetic plates 10 and 11 change.
Accordingly, the output signal S2 has an output signal waveform indicated by a dotted line S2 ', and a phase difference occurs between the output signals S1 and S2. The amount of twist of the torsion bar 4 is determined by the output signal S
It is substantially proportional to the difference in phase difference between S1 and S2. Torque sensor 5
No. 1 captures this phase difference deviation as a torque amount. As described above, in order to measure the amount of twist of the torsion bar 4 in a non-contact manner, the magnetoresistive elements 21 to 24 are disposed in the case 55 that is mechanically independent of the shafts 2 and 3. By measuring the torque generated between the two in a non-contact manner, a highly durable torque sensor 51 can be obtained.

A torque sensor 51 in which the magnetic plates 10 and 11 are replaced by elliptical magnetic plates 61 as shown in FIG.
A may be used. In the second embodiment, the magnetic plates 10 and 11 are fixed to the shafts 2 and 3 at positions eccentric from the center of the circle in the same direction. May be fixed to the shafts 2 and 3. in this case,
The phase difference between the output signals S1 and S2 is 180 degrees, and an output signal waveform similar to the graph shown in FIG. 5 is obtained.

[Third Embodiment, FIGS. 11 to 14] FIG.
As shown in FIG. 12 and FIG. 12, the torque sensor 71 of the third embodiment is different from the torque sensor 1 of the first embodiment in that
Further, magnetoresistive elements 25 to 28 are added.

In the outer peripheral wall portion of the case 55, torque detecting holes 56, 5 are provided at positions separated by 90 degrees and in the axial direction of the shafts 2, 3.
8 and torque detecting holes 57 and 59 are provided side by side. The torque detecting holes 56 to 59 accommodate magnetoresistive elements 21 to 28 and magnets M1 to M4 for applying a bias magnetic field to the magnetoresistive elements 21 to 28, respectively. The magnetoresistive elements 21, 22, 25 and 26 are arranged so as to face the outer peripheral end face 10 a of the magnetic plate 10. Magnetic resistance element 2
3, 24, 27 and 28 are outer peripheral end surfaces 11 of the magnetic plate 11;
a. These magnetoresistive elements 21 to 28 are electrically connected as shown in FIG.

Next, the operation and effect of the torque sensor 71 having the above configuration will be described. In the torque sensor 71,
When no torque is generated between the steering-side shaft 2 and the steering-mechanism-side shaft 3, the output terminals 43 to 46 are connected to the magnetic plates 10 and 1 respectively.
Each time one rotation is performed, one cycle of sine wave output signals S1 to S4 as shown in FIG. 14 are output. The output signals S1 and S2 have a phase difference of 180 degrees. Output signal S1
And S3 and the output signals S2 and S4 have a phase difference of 9 respectively.
0 degrees.

On the other hand, when torque is generated between the steering shaft 2 and the steering mechanism shaft 3 and the torsion bar 4 is twisted, the relative positions of the magnetic plates 10 and 11 change. Therefore, the output signals S2 and S4 have the output signal waveforms indicated by the dotted lines S2 'and S4', and the output signals S2 and S4 have a phase difference between the output signals S1 and S3, respectively. The amount of twist of the torsion bar 4 is determined by the output signal S
It is substantially proportional to the difference in phase difference between S1 and S2 and the difference in phase difference between output signals S3 and S4. The torque sensor 71 captures the deviation of the phase difference as a torque amount.

Here, when the output signals S1 and S2 are at the peak value of the sine wave, the change in the output voltage of the output signals S1 and S2 with respect to the amount of twist of the torsion bar 4 is small. Therefore, when the torsion bar 4 is slightly twisted,
It is difficult to accurately detect the amount of torque due to the phase difference between the output signals S1 and S2. On the other hand, output signals S3 and S4
Is located at the zero crossing point of the waveform, and is at a position where the highest sensitivity can be obtained. Therefore, in such a case, the torque amount is detected by the output signals S3 and S4 having a large phase difference. Thus, it is possible to obtain the torque sensor 71 that can more accurately detect the torque amount.

The positional relationship between the magnetoresistive elements 21 to 28 is determined by the phase difference between the output signals S1 and S3 and the output signals S2 and S3.
4 is preferably 90 degrees, but is not necessarily limited to this, and the output signal S
The positional relationship does not matter as long as the phase angles of 1 to S4 are different.

[Fourth Embodiment, FIGS. 15 and 16] FIG.
As shown in FIGS. 5 and 16, the torque sensor 81 of the fourth embodiment is obtained by adding magnetoresistive elements 25 to 28 to the torque sensor 51 of the second embodiment (the magnetoresistive element 28 is shown in the drawing). Zez). In the outer peripheral wall portion of the case 55, the torque detecting holes 56, 58,
9. Torque detection holes 82 and 84 and torque detection hole 8
3 and 85 are provided side by side (torque detection holes 8
5 is not shown). Torque detection holes 56 to 59, 82 to 8
5, magnets M1 to M8 for applying a bias magnetic field to the magnetoresistive elements 21 to 28 and the magnetoresistive elements 21 to 28, respectively.
(The magnet M8 is not shown). Magnetic resistance element 2
1 and 22, and the magneto-resistive elements 25 and 26 are provided at positions symmetrical with respect to the steering shaft 2, respectively, and are arranged to face the outer peripheral end surface 10a of the magnetic plate 10. The magnetoresistive elements 23 and 24 and the magnetoresistive elements 27 and 28 are respectively provided at positions symmetrical with respect to the steering mechanism side shaft 3 and are arranged so as to face the outer peripheral end face 11 a of the magnetic plate 11. ing. These magnetoresistive elements 21 to 28 are electrically connected as shown in FIG.

The torque sensor 81 having the above configuration is used for the third sensor.
The same effect as that of the torque sensor 71 of the embodiment can be obtained.

[Fifth Embodiment, FIGS. 17 to 19] FIG.
As shown in FIG. 18 and FIG. 18, the torque sensor 91 of the fifth embodiment differs from the torque sensor 1 of the first embodiment in that
Instead of the flat magnetic plates 10 and 11, circular or elliptical magnetic plates 92 and 93 bent at a position passing through the center are used. The steering shaft 2 and the steering mechanism shaft 3 are fixed at the center positions of the magnetic plates 92 and 93.

The torque sensor 91 having the above configuration is
When the magnetic plates 92 and 93 make one rotation, their end surfaces 92a and
93a is repeatedly displaced in the vertical direction twice as viewed from the magnetoresistive elements 21 to 24. Accordingly, when no torque is generated between the steering shaft 2 and the steering mechanism shaft 3, the magnetic plate 9
Each time 2, 93 makes one rotation, it outputs sine wave output signals S1, S2 of two cycles as shown in FIG. On the other hand, when a torque is generated between the steering shaft 2 and the steering mechanism shaft 3, the output signal S2 has an output signal waveform indicated by a dotted line S2 '. This makes it possible to obtain a torque sensor 91 having a greater sensitivity to a phase difference shift than a torque sensor that outputs an output signal of one cycle every time the magnetic plate rotates once.

[Sixth Embodiment, FIGS. 20 and 21] FIG.
0, the torque sensor 101 of the sixth embodiment
In the torque sensor 1 of the first embodiment, ring magnets 102 and 103 whose outer peripheral ends are magnetized are used in place of the magnetic plates 10 and 11.

The ring magnets 102 and 103 are inclined with respect to the axes 2 and 3, respectively. The inclination direction of the ring magnet 103 is different from the inclination direction of the ring magnet 102 by 90 degrees. The magnets M1 and M2 for applying a bias magnetic field to the magnetoresistive elements 21 to 24 are ring magnets 10
Magnetic poles (S-poles) different from the magnetic poles (N-poles) magnetized on the outer peripheral ends of the ring magnets 2 and 103 are magnetized on the surfaces on the ring magnets 102 and 103 side.

The torque sensor 101 having the above configuration
When no torque is generated between the steering-side shaft 2 and the steering-mechanism-side shaft 3, each time the ring magnets 102 and 103 make one rotation, a one-cycle sine wave output signal S as shown in FIG.
1 and S2 are output. On the other hand, when a torque is generated between the steering shaft 2 and the steering mechanism shaft 3, the output signal S2 becomes
The output signal waveform is indicated by the dotted line S2 '.

At this time, the magnets M1 and M2 and the ring magnet 1
02 and 103, an attractive force is generated, and the magnet M
A large magnetic flux is generated between the ring magnets 1 and M2 and the ring magnets 102 and 103. The magnetoresistive elements 21 to 24 become more sensitive as the magnetic flux increases, and the magnetoresistive elements 21 to 24
, The output signals S1 and S2 are increased. As a result, it is possible to obtain the torque sensor 101 having high torque amount detection accuracy.

[Other Embodiments] The torque sensor according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist. In the above-described embodiment, the magnetoresistive element is used as the magnetoelectric conversion element. However, the present invention is not limited to this, and a Hall element, a ferromagnetic thin film element, an MR element, or the like may be used. Also,
The output signals S1 to S4 may be triangular waves or the like in addition to the sine waves.

[0054]

As is apparent from the above description, according to the present invention, the magneto-electric conversion element is disposed so as to face the outer peripheral end surface of the magnetic plate fixed to the rotating shaft. Can detect the torque generated on the rotating shaft in a non-contact manner while being mechanically independent of the rotating shaft. Furthermore, since the mechanism does not have a contact portion, it is possible to perform complete non-contact detection. In addition, since there are few machined parts and the configuration is simple, a low-cost torque sensor can be obtained.

If the detection signal of two or more cycles is output during one rotation of the shaft, the sensitivity to the phase difference shift can be increased as compared with the case of one cycle.

Further, a magneto-electric conversion element is further opposed to the outer peripheral end faces of the plurality of magnetic plates so as to output a detection signal having a phase angle different from the detection signal output from the magneto-electric conversion element. By arranging, when it is difficult to detect a phase difference shift of one of the detection signals, the phase difference shift can be detected by using the other detection signal. Thus, more accurate torque detection can be performed.

Further, when the magnetic plate is a magnet magnetized at the outer peripheral end, a strong magnetic field is applied to the magnetoelectric conversion element, and the sensitivity of the magnetoelectric conversion element can be increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a torque sensor according to the present invention.

FIG. 2 is a cross-sectional view of the torque sensor shown in FIG.

FIG. 3 is a perspective view of a magnetoresistive element used in the torque sensor shown in FIG.

FIG. 4 is an electric circuit diagram of the torque sensor shown in FIG.

FIG. 5 is a graph showing an output signal waveform of the torque sensor shown in FIG.

FIG. 6 is a longitudinal sectional view showing a modified example of the torque sensor shown in FIG. 1;

FIG. 7 is a graph showing an output signal waveform of the torque sensor shown in FIG. 6;

FIG. 8 is a longitudinal sectional view showing a second embodiment of the torque sensor according to the present invention.

9 is a transverse sectional view of the torque sensor shown in FIG.

FIG. 10 is a transverse sectional view showing a modification of the torque sensor shown in FIG. 8;

FIG. 11 is a longitudinal sectional view showing a third embodiment of the torque sensor according to the present invention.

FIG. 12 is a transverse sectional view of the torque sensor shown in FIG. 11;

FIG. 13 is an electric circuit diagram of the torque sensor shown in FIG. 11;

FIG. 14 is a graph showing an output signal waveform of the torque sensor shown in FIG. 11;

FIG. 15 is a longitudinal sectional view showing a fourth embodiment of the torque sensor according to the present invention.

16 is a cross-sectional view of the torque sensor shown in FIG.

FIG. 17 is a longitudinal sectional view showing a fifth embodiment of the torque sensor according to the present invention.

18 is a transverse sectional view of the torque sensor shown in FIG.

FIG. 19 is a graph showing an output signal waveform of the torque sensor shown in FIG.

FIG. 20 is a longitudinal sectional view showing a sixth embodiment of the torque sensor according to the present invention.

21 is a graph showing an output signal waveform of the torque sensor shown in FIG.

[Explanation of symbols]

1, 1A, 51, 51A, 71, 81, 91, 101 ...
Torque sensor 2 Steering side shaft 3 Steering mechanism side shaft 4 Torsion bar 10, 11, 61, 92, 93 Magnetic plate 10a, 11a, 61a, 92a, 93a Outer peripheral end surface 21-28 Magnetic resistance element 102 , 103: Ring magnets M1 to M8: Bias magnets

Claims (6)

[Claims] 1. A torque sensor which is coaxially connected via a torsion bar and detects the rotational torque on a plurality of shafts which can be relatively rotated and displaced by torsion of the torsion bar when a rotational torque is applied. A plurality of magnetic plates fixed to each of the plurality of shafts, the positions of which change with the rotation of the shafts; and a plurality of magnetic plates arranged opposite to the outer peripheral end surfaces of the plurality of magnetic plates, A magneto-electric conversion element that detects a change in the position of a plurality of magnetic plates, wherein the magnetic plates are inclined with respect to the axis. 2. A method according to claim 1, wherein at least two magneto-electric conversion elements arranged opposite to an outer peripheral end face of said magnetic plate are arranged side by side in a direction parallel to an axial direction for each magnetic plate. The torque sensor according to claim 1, wherein: 3. A torque sensor which is coaxially connected via a torsion bar and detects the rotational torque on a plurality of shafts which can be relatively rotated and displaced by a twist of the torsion bar when a rotational torque is applied. A plurality of magnetic plates fixed to each of the plurality of shafts, the positions of which change with the rotation of the shafts; and A magneto-electric conversion element for detecting a change in the position of a plurality of magnetic plates, wherein the magnetic plates are fixed to the shaft at a position eccentric from the center. 4. At least two magneto-electric conversion elements disposed opposite to an outer peripheral end face of the magnetic plate are disposed at positions symmetrical with respect to an axis for each of the magnetic plates.
The torque sensor according to claim 3, wherein the two magnetoelectric conversion elements are connected in series. 5. The torque sensor according to claim 1, wherein the magnetic plate has one of a circular shape and an elliptical shape. 6. A magneto-electric conversion device further comprising a plurality of magneto-electric conversion devices opposed to outer peripheral end surfaces of the plurality of magnetic plates so as to output a detection signal having a phase angle different from a detection signal output from the magneto-electric conversion device. The torque sensor according to claim 1, wherein the torque sensor is arranged.