JP2003090774A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor which has a large detection output and stable quality, and which can be manufacturable at a low cost and can ensure stable steering performance. SOLUTION: A first and second sensor rings 2, 6, are extended in the circumferential direction cylindrically around a torsion bar 90, teeth 3a, 5a, are formed in combteeth shape on the outside of the first sensor ring 2, and teeth 7a, 9a, 11a facing the first sensor ring 2 in the radial direction are formed like combteeth on the inside of the second sensor ring 6. The first and second sensor rings 2, 6 and a third magnetic body 60 have their respective magnetic parts 3, etc., magnetically divided in the axial direction by a PBT-made nonconductive magnetic part 4, etc. The first sensor ring 2 and the third magnetic body 60 have two magnetic parts 3, etc. The magnetic parts 12 of the third magnetic body 60 house coils 14, 17, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor applicable to electric power steering and the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
A torque sensor disclosed in Japanese Patent Publication No. 0-146722 is known. In this torque sensor, a torsion bar 90 extends in the axial direction, and a hollow input shaft 91 as a first shaft coaxial with the torsion bar 90 is connected to the upper end of the torsion bar 90 by a pin 96. There is. A steering wheel (not shown) of the vehicle is connected to the upper portion of the input shaft 91.

At the lower end of the torsion bar 90, there is provided a second shaft coaxial with the torsion bar 90 and the input shaft 91.
A hollow output shaft 92 as a shaft is connected by spline fitting and press fitting, and a pinion 92a is integrally formed at a lower portion of the output shaft 92.

An upper housing 93 and an under housing 94 are provided on the outer circumferences of the input shaft 91 and the output shaft 92 via bearings 95a and 95b, and the under housing 94 meshes with a pinion 92a of the output shaft 92. The rack 81 is held. This rack 81 is provided with a motor (not shown) that assists the steering force.

In the upper housing 93, a first sensor ring 97 as a first magnetic body made of a magnetic material is fixed to the input shaft 91. As shown in FIG. 11, the first sensor ring 97 has a cylindrical shape that extends in the circumferential direction surrounding the torsion bar 90, and the lower end surface of the first sensor ring 97 has a comb-teeth shape. Many rectangular tooth portions 97a are formed as one protrusion.

Further, in the upper housing 93, as shown in FIG. 10, a second sensor ring 98 as a second magnetic body made of a magnetic material is fixed to the output shaft 92. As shown in FIG. 11, the second sensor ring 98 also has a cylindrical shape extending in the circumferential direction surrounding the torsion bar 90, and the upper end surface of the second sensor ring 98 has a comb-teeth shape. Many rectangular teeth 98a as two protrusions
Are formed. Each tooth portion 98a faces each tooth portion 97a with a phase shift while having a gap in the axial direction.

Further, in the upper housing 93,
As shown in FIG. 10, the first and second sensor rings 97, 98.
A coil 99 facing from the outer peripheral side is fixed to. Further, the coil 99 is surrounded and the first and second sensor rings 9 are enclosed.
A guide 85 and a spacer 86 as a third magnetic body are fixed so as to form a magnetic circuit with 7, 98.
The coil 99 is an interface circuit (hereinafter, I
/ F circuit. ) 80, and the I / F circuit 80 is connected to a microcomputer (not shown) (not shown).

In this torque sensor, when the torque is transmitted to the input shaft 91 by the operation of the steering wheel of the vehicle, the torsion bar 90 is twisted to cause relative displacement between the input shaft 91 and the output shaft 92. As a result, the facing areas of the tooth portions 97a and 98a of the first and second sensor rings 97 and 98 change, and the inductance of the coil 99 changes. This change in inductance is input to the microcomputer via the I / F circuit 80. Therefore, in the electric power steering employing this torque sensor, the steering force corresponding to the torque is assisted by the motor to the rack 81.

[0009]

However, in the above-mentioned conventional torque sensor, since the tooth portions 97a, 98a of the first and second sensor rings 97, 98 are axially opposed to each other, the coil for detecting torque is detected. Only one 99 is provided. Therefore, when the reliability of the signal obtained from the coil 99 decreases, for safety reasons, the assist of the steering force by the motor must be stopped, and stable steering performance of the vehicle cannot be obtained.

If, in this torque sensor, two or more magnetic circuits are formed in order to provide two or more coils for detecting the torque, each protrusion of each sensor ring faces each other in the axial direction, which is extremely complicated. However, it is difficult to manufacture.

Further, in the above conventional torque sensor, the tooth portions 97a and 98a of the first and second sensor rings 97 and 98 are formed.
Are opposed to each other in the axial direction, the length of the gap between the tooth portions 97a and 98a easily changes during assembly. For this reason, the inductance changes greatly for each torque sensor, and variations in quality are likely to occur.

In this respect, the applicant proposed a torque sensor in which the first protrusion of the first magnetic body and the second protrusion of the second magnetic body face each other in the radial direction (Japanese Patent Application No. 2000-368240). In this torque sensor, the first magnetic body and the second magnetic body have a cylindrical shape extending in the circumferential direction surrounding the torsion bar. A first protrusion is formed on the outer periphery of the first magnetic body in a comb-teeth shape, and a second protrusion that faces the first protrusion in the radial direction is formed on the inner periphery of the second magnetic body in a comb-teeth shape. Has been done. Also,
At least the first magnetic body and the third magnetic body each have a magnetic portion made of two or more magnetic materials that are magnetically separated in the axial direction by a nonmagnetic portion made of a nonmagnetic material. A coil is housed in each magnetic portion of the third magnetic body.

According to this torque sensor, the magnetic circuit has two
Since the above is formed, each coil can detect the torque independently. Therefore, even if the reliability of one magnetic circuit is reduced, the torque can be detected by the other coil, so that stable steering performance can be ensured. In addition, since the radial length of the gap between the first protrusion and the second protrusion does not change substantially during assembly, the inductance does not change significantly for each torque sensor, and variations in quality are less likely to occur. Thus, this torque sensor
Stable steering performance can be secured, and quality can be stabilized.

However, in this torque sensor, the non-magnetic portion such as the first sensor ring has a conductive SU.
When it is made of austenitic stainless steel such as S304, eddy current is generated in the non-magnetic parts when the first sensor ring and the like are relatively displaced. Further, when the non-magnetic portion is formed by machining austenitic stainless steel, the non-magnetic portion is magnetized, and the eddy current is included in the non-magnetic portion. Therefore, the change in the inductance of the coil is reduced due to the loss due to the eddy current, which in turn lowers the detection output.

Further, the magnetic portion such as the first sensor ring is attached to the SU.
If it is made of ferritic stainless steel such as S430 and the non-magnetic part such as the first sensor ring is made of the above austenitic stainless steel, the thermal expansion coefficient of both is different, but the rigidity of both is high, so a high temperature state is required. Residual stress is generated in the magnetic part during manufacturing of the first sensor ring and the like. Therefore, the change in the inductance of the coil is reduced or varies due to the loss due to the residual stress, which in turn lowers the detection output or causes variations.

Further, since austenitic stainless steel has a relatively high material cost and processing cost, and it is necessary to use a special joining method for the magnetic portion made of ferritic stainless steel or the like, parts such as the first sensor ring are formed. The cost and eventually the manufacturing cost of the torque sensor increase.

The present invention has been made in view of the above-mentioned conventional circumstances, and has a large detection output, can be manufactured at low cost, and can ensure stable steering performance, and thus stable quality. It is an issue to be solved to provide a torque sensor.

[0018]

The torque sensor of the present invention comprises a torsion bar extending in the axial direction, a first shaft connected to one end of the torsion bar and coaxial with the torsion bar, and the torsion bar. A second shaft connected to the other end of the first shaft and coaxial with the torsion bar and the first shaft;
A first magnetic body fixed to the shaft and having a first protrusion, and a second magnetic body fixed to the second shaft and having a second protrusion facing the first protrusion.
A magnetic body, a coil facing the first magnetic body and the second magnetic body, and a third magnetic body that surrounds the coil and forms a magnetic circuit with the first magnetic body and the second magnetic body. Have
In the torque sensor for detecting the torque based on the inductance, the coil has an inductance that changes in response to a change in the facing area of the first protrusion and the second protrusion based on the twist acting on the torsion bar. The first magnetic body and the second magnetic body have a cylindrical shape extending in the circumferential direction surrounding the torsion bar, and the first protrusion is formed on the outer periphery of the first magnetic body in a comb-teeth shape. The second protrusion, which faces the first protrusion in the radial direction, is formed in a comb-teeth shape on the inner circumference of the second magnetic body, and the first magnetic body, the second magnetic body, and the third magnetic body are formed. At least one of the bodies is characterized by having a magnetic portion made of a magnetic material axially magnetically divided by a non-conductive non-magnetic portion made of a non-conductive non-magnetic material.

In the torque sensor of the present invention, the first magnetic body,
At least one of the second magnetic body and the third magnetic body has a non-conductive non-magnetic portion made of a non-conductive non-magnetic material. Does not occur. Further, the non-conductive non-magnetic portion is not magnetized, and an eddy current is not included in the non-conductive non-magnetic portion. Therefore, the change in the inductance of the coil is not reduced, and a high detection output can be maintained.

When the non-conductive non-magnetic portion such as the first magnetic body is made of a non-conductive non-magnetic material, the magnetic portion such as the first magnetic body is made of ferritic stainless steel such as SUS430. Even if the coefficient of thermal expansion is different,
If the non-conductive non-magnetic material is a highly elastic resin, the non-conductive non-magnetic part absorbs the distortion of the magnetic part. If the non-conductive non-magnetic material is a resin, the temperature at the time of injection of the resin is lower than the temperature at which the metals are melted, and the distortion of the magnetic part is not so large. In this way, residual stress is unlikely to occur in the magnetic part. For this reason, the change in the inductance of the coil is not small, and variation is unlikely to occur. Therefore, a high and stable detection output can be maintained. If PPS (polyphenylene sulfide) having a thermal expansion coefficient similar to that of ferritic stainless steel is used as the resin, peeling may occur between the non-conductive non-magnetic part made of PPS and the magnetic part made of ferritic stainless steel. It can be prevented.

Further, resin and ceramics as the non-conductive non-magnetic material have a relatively low material cost. If it is a resin, the processing cost is low, and it is possible to easily join the magnetic portion made of ferritic stainless steel or the like by resin molding. Therefore, the cost of parts such as the first magnetic body,
As a result, the manufacturing cost of the torque sensor can be reduced.

Therefore, in the torque sensor of the present invention,
It has a large detection output, can be manufactured at low cost, and can ensure stable steering performance, thus exhibiting stable quality.

In the torque sensor of the present invention, for example, the first
The magnetic body is composed of two or more cylindrical magnetic parts that are magnetically separated and fixed with respect to the first axis, and a non-conductive non-magnetic part that is integrally provided between the magnetic parts. The second magnetic body is composed of three or more cylindrical magnetic parts and a non-conductive non-magnetic part integrally provided between the magnetic parts, and the two adjacent magnetic parts of the second magnetic body. Respectively face one of the magnetic portions of the first magnetic body in the radial direction, and the third magnetic body includes two or more magnetic portions and a non-conductive non-magnetic portion integrally provided between the magnetic portions. Each of the magnetic portions of the third magnetic body can face two adjacent magnetic portions of the second magnetic body in the radial direction.

In this case, the first magnetic substance and the third magnetic substance are 1
The non-conductive non-magnetic part may be sandwiched between the two magnetic parts, and the second magnetic body may have three non-conductive non-magnetic parts sandwiched between the three magnetic parts.

Further, in the torque sensor of the present invention, for example, the first magnetic body is composed of two cylindrical magnetic portions fixed to the first shaft without being magnetically divided, and the magnetic portions. And a non-conductive non-magnetic portion that is integrally provided between the magnetic portions, and the second magnetic body includes two cylindrical magnetic portions and a non-conductive non-magnetic portion that is integrally provided between the magnetic portions. And each of the magnetic portions of the second magnetic body faces one of the magnetic portions of the first magnetic body in the radial direction, and the third magnetic body between the two magnetic portions and each of the magnetic portions. The non-conductive non-magnetic portion may be integrally provided, and each magnetic portion of the third magnetic body may face one magnetic portion of the second magnetic body in the radial direction.

The first protrusion or the second protrusion whose magnetic parts face each other.
Has a protrusion. The magnetic portion can expose not only the first protrusion or the second protrusion but also the tooth gap between the first protrusion or the second protrusion from the non-conductive non-magnetic portion. Is exposed from the non-conductive non-magnetic portion, and the tooth gap between the first protrusions or the second protrusions is preferably not exposed from the non-conductive non-magnetic portion. Such a torque sensor has a magnetic part embedded in the non-conductive non-magnetic part, which facilitates manufacturing.

In the torque sensor of the present invention, resin can be used as the non-conductive non-magnetic material. In this case, the first magnetic body, the second magnetic body, and the third magnetic body can be resin-molded by holding the magnetic portion in the cavity and injecting the resin. Therefore, the non-conductive non-magnetic portion and the magnetic portion can be firmly joined to each other, and the quality of the torque sensor is stabilized. Further, since the material cost and the processing cost of the resin are lower than the material cost and the processing cost of stainless steel, the cost reduction of the torque sensor can be realized by using the resin as the non-conductive non-magnetic material. As the resin, it is preferable to adopt PBT (polybutylene terephthalate), PPS, or the like. Since these resins have excellent heat resistance and impact resistance, a torque sensor having excellent heat resistance and impact resistance can be obtained.

Further, in the torque sensor of the present invention, ceramics can be adopted as the non-conductive non-magnetic material. In this case, the torque sensor having excellent heat resistance can be obtained. Alumina is preferably used as the ceramic. In this case, the torque sensor can be made particularly excellent in heat resistance.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments 1 to 3 embodying the present invention will be described below with reference to the drawings.

(First Embodiment) The main mechanical structure of the torque sensor of the first embodiment is the same as that of FIG. 10 as shown in FIG. 1, and is the same as the conventional mechanical structure shown in FIG. The same reference numerals will be used for the configurations of the above, and the description thereof will be omitted.

In this torque sensor, as shown in FIG. 1, in an upper housing 93, a ring 1 made of a non-magnetic material is fixed to an input shaft 91 as a first shaft, and the ring 1 is provided with a first A first sensor ring 2 as a magnetic body is provided. As a result, the first sensor ring 2 is magnetically separated from the input shaft 91. As shown in FIG. 2, the first sensor ring 2 includes, from the input shaft 91 side, a cylindrical first magnetic portion 3, a cylindrical first non-conductive non-magnetic portion 4, and a cylindrical second magnetic portion. It consists of part 5. The first and second magnetic parts 3 and 5 are made of SUS430 which is ferritic stainless steel, and the first non-conductive non-magnetic part 4 is made of PBT.

The first and second magnetic portions 3 of the first sensor ring 2,
5 is a torsion bar 90 as shown in FIGS. 3 and 4.
It has a cylindrical shape that extends in the circumferential direction surrounding the first,
A large number of rectangular tooth portions 3a, 5a are formed on the outer peripheral surfaces of the two magnetic portions 3, 5 as comb-shaped first protrusions.

The first non-conductive non-magnetic portion 4 of the first sensor ring 2 also has a cylindrical shape extending in the circumferential direction surrounding the torsion bar 90, and the first and second magnetic portions 3 and 5 are embedded therein. is doing. The tooth portions 3a, 5a are exposed from the first non-conductive non-magnetic portion 4, and the tooth gap between the tooth portions 3a, 5a is formed by the first non-conductive non-magnetic portion 4.
Not exposed from.

Further, as shown in FIG. 1, in the upper housing 93, the output shaft 92 as the second shaft is provided.
A second sensor ring 6 as a second magnetic body is provided above the. As shown in FIG. 2, the second sensor ring 6 includes, from the input shaft 91 side, a cylindrical third magnetic portion 7, a cylindrical second non-conductive non-magnetic portion 8, and a cylindrical fourth magnetic portion. It comprises a part 9, a third non-conductive non-magnetic part 10 having a cylindrical shape, and a fifth magnetic part 11 having a cylindrical shape. 3rd, 4th, 5th
The magnetic parts 7, 9, 11 are made of SUS430,
The non-conductive non-magnetic parts 8 and 10 are made of PBT.

The third, fourth and fifth magnetic portions 7, 9 and 11 of the second sensor ring 6 also have a cylindrical shape extending in the circumferential direction surrounding the torsion bar 90 as shown in FIGS. 3 and 4. In addition, a large number of rectangular tooth portions 7a, 9 are formed on the inner peripheral surface of the third, fourth, fifth magnetic portions 7, 9, 11 as comb-shaped second protrusions.
a and 11a are formed.

The second and third non-conductive non-magnetic portions 8 and 10 of the second sensor ring 6 also have a cylindrical shape extending in the circumferential direction surrounding the torsion bar 90, and have the third, fourth and fifth magnetic elements inside. The parts 7, 9 and 11 are buried. Teeth 7a, 9a, 11a
Is exposed from the second and third non-conductive non-magnetic portions 8 and 10, and the tooth portion 7
The tooth space between a, 9a and 11a is not exposed from the second and third non-conductive non-magnetic parts 8 and 10. In order to improve the sensor sensitivity, the tooth portions 3a, 5 of the first and second sensor rings 2, 6 are
a, 7a, 9a, 11a are the first to third non-electric nonmagnetic parts 4,
Although it is preferable to expose from No. 8 and 10, even if it is not exposed, it is sufficient that a change in inductance can be detected by the tooth portions 3a, 5a, 7a, 9a and the tooth groove.

Tooth portions 3a and 5a of the first and second magnetic portions 3 and 5, respectively.
And the tooth portions 7a, 9 of the third, fourth, fifth magnetic portions 7, 9, 11
a and 11a have a common center O. Further, the tooth portions 3a, 5a of the first and second magnetic portions 3, 5 have a gap length 1 in the radial direction, while having the third, fourth, fifth magnetic portions 7,
The tooth portions 7a, 9a and 11a of 9 and 11 are faced.

Furthermore, the center line L0 connected to the center O of each tooth 7a, 9a, 11a and the center line L1 connected to the center O of the tooth 3a form an angle of θ. Also, each tooth 7
The center line L0 connected to the center O of a, 9a, 11a and the center line L2 connected to the center O of the tooth portion 5a form an angle of θ in the direction opposite to the angle formed by the center line L0 and the center line L1. ing.

The tooth spaces between the tooth portions 3a, 5a, 7a, 9a, 11a of the first and second sensor rings 2, 6 are not limited to the bottomed grooves shown in FIG. 3 and FIG. It can also be configured as shown in FIG. Although FIG. 6 shows the second sensor ring 6, the same applies to the first sensor ring 2. That is, through holes a are formed in the cylindrical magnetic body so as to extend axially from the inner side to the outer side, and a non-conductive non-magnetic material is embedded in each through hole a to form the non-conductive non-magnetic portions 4, 8, 10. It may be configured. For example, PBT as a non-conductive non-magnetic material is embedded in the through hole a. In this case, the remaining portion b other than the through hole a is the tooth portions 3a, 5a, 7a, 9a, 11 as the first and second protrusions formed in a comb shape in the present invention.
It corresponds to a.

Further, as shown in FIGS. 1 and 2, the inside of the upper housing 93 is composed of two sets of guides 12, 15, spacers 13, 16 and a separator 18 to form the third magnetic body 6.
0 is configured. Guides 12 and 15 and spacer 1
Reference numerals 3 and 16 are made of SUS430, are separated by a separator 18 made of PBT which is a non-conductive non-magnetic material, and are fixed by a circlip 19. The guides 12, 15, the spacers 13, 16 and the separator 18 also have a cylindrical shape that extends in the circumferential direction surrounding the torsion bar 90 and cover the outer peripheral surface of the second sensor ring 6.

Then, the first magnetic portion 3, the third magnetic portion 7, the guide 12, the spacer 13 and the fourth magnetic portion 9 form one magnetic circuit. Further, another magnetic circuit is formed by the second magnetic unit 5, the fifth magnetic unit 11, the guide 15, the spacer 16 and the fourth magnetic unit 9. And the coil 14,
17 are arranged in each magnetic circuit.

Further, as shown in FIG. 7, coils 14, 1
7 is connected to the I / F circuit 20. I / F circuit 20
Is the original oscillator circuit 21, and the original oscillator circuit 21 and the coil 1
4 and a second oscillator circuit 24 connected between the original oscillator circuit 21 and the coil 17.
And a torque detection / processing circuit 23 connected to the coil 14.
And a torque detection / processing circuit 25 connected to the coil 17
And have.

The torque sensor of the first embodiment configured as described above can be manufactured as follows.

First, the second sensor ring 6 injects PBT into the cavity of the injection molding die in which the third magnetic portion 7, the fourth magnetic portion 9 and the fifth magnetic portion 11 are arranged in advance, and this PB is injected.
The second non-conductive non-magnetic portion 8 and the third non-conductive non-magnetic portion 10 are integrally manufactured by T. In this way, the third, fourth and fifth magnetic parts 7, 9 and 11 are embedded in the second and third non-conductive non-magnetic parts 8 and 10. The first sensor ring 2 is manufactured similarly.

The first sensor ring 2 and the second sensor ring
A torque sensor is assembled using the sensor ring 6. First, the second sensor ring 6 is pressed into the output shaft 92. Further, the torsion bar 90 is connected to the output shaft 92.
Fixed to.

On the other hand, after pressing the ring 1 into the input shaft 91, the first sensor ring 2 is pressed into the ring 1. Then, after fixing the upper housing 93 to the input shaft 91 via the bearing 95a, the coil 14,
The third magnetic body 60 assembled by inserting 17 into the inside is inserted into the upper housing 93. And guide 15
Is fixed to the upper housing 93 by the circlip 19.

After that, the input shaft 91 is inserted from the axial direction of the torsion bar 90, and the input shaft 91 and the torsion bar 90 are connected by a pin as in the case of FIG. In this way, the torque sensor of the first embodiment is manufactured.

In this torque sensor, as shown in FIG. 7, the oscillation signal output from the original oscillation circuit 21 of the I / F circuit 20 is timed by the first and second oscillation circuits 22 and 24, and the coil 14 , 17 are applied. As a result, two magnetic circuits are formed as shown in FIG.
The orientations of these two magnetic circuits are opposite, as indicated by the arrows. Here, when torque is transmitted to the input shaft 91 by operating the steering wheel of the vehicle, the torsion bar 90 is twisted to cause relative displacement between the input shaft 91 and the output shaft 92. As a result, the tooth portions 3a and 5a of the first and second magnetic portions 3 and 5 and the third to fifth portions are formed.
The facing area of the tooth portions 7a, 9a, 11a of the magnetic portions 7, 9, 11 changes. Then, the magnetic flux density changes, which appears as a change in the inductance of the coils 14 and 17. Then, the inductances of the coils 14 and 17 are detected by the torque detection / processing circuits 23 and 25, processed, and then input to a microcomputer (not shown) as torque signals T1 and T2.

In this torque sensor, the coils 14 and 17 are
Detects the change in inductance independently,
Even if the detected value of one of the coils 14 and 17 becomes unreliable, the torque can be known from the detected value of the other. Therefore, even in such a case, it is not necessary to stop the assist of the steering force by the motor.

Further, the tooth portions 3a of the first and second magnetic portions 3 and 5,
5a and the tooth portions 7a, 9a of the third to fifth magnetic portions 7, 9, 11;
11a in the radial direction face each other.
There is almost no change in the radial length l of the gap between the teeth a, 5a and the teeth 7a, 9a, 11a. For this reason, the inductance does not change significantly for each torque sensor, and variations in quality are less likely to occur.

Further, the change in the magnetic characteristics due to temperature and the like can be compensated for by the differential of the torque signals by the coils 14 and 17.

Further, from the relationship between the tooth portions 3a and 5a with respect to the tooth portions 7a, 9a and 11a, the sensor sensitivity can be doubled by adopting the inductance bridge circuit. That is, the center line L0 of each tooth 7a, 9a, 11a and the center line L1 of the tooth 3a are
It has opposite angles with respect to the center line L0 of 9a and 11a and the center line L2 of the tooth portion 5a. Thereby, as a result of the relative displacement between the input shaft 91 and the output shaft 92, for example, when the facing area between the tooth portions 7a, 9a and the tooth portion 3a becomes large, the tooth portions 9a, 11a and the tooth portion 3a The facing area with 5a becomes small. On the contrary, when the facing area between the tooth portions 7a, 9a and the tooth portion 3a becomes small, the tooth portions 9a, 11a
The facing area between the tooth and the tooth portion 5a becomes large. In this way, since the changes in the inductances of the coils 14 and 17 are relatively reversed, the sensor sensitivity can be doubled.

Further, the non-conductive non-magnetic parts 4 of the first sensor ring 2, the second sensor ring 6 and the third magnetic body 60,
Since 8, 10 and 18 are made of PBT which is a non-conductive non-magnetic material, no eddy current is generated in each non-conductive non-magnetic part 4, 8, 10 and 18 when the first sensor ring 2 and the like are relatively displaced. . Further, the non-conductive non-magnetic parts 4, 8, 10 and 18 are not magnetized, and eddy currents are not included in the non-conductive non-magnetic parts 4, 8, 10 and 18. Therefore, the coils 14, 17
The change in the inductance is not small, and a high detection output can be maintained.

In addition, each non-conductive non-magnetic part 4, 8, 10, 1
Reference numeral 8 is a PBT, and includes the first and second magnetic portions 3 and 5 of the first sensor ring 2, the third, fourth and fifth magnetic portions 7, 9 and 11 of the second sensor ring 6, and the guide 12 of the third magnetic body 60. , 15
Since the spacers 13 and 16 are made of SUS430,
Distortion occurs due to the difference in the coefficient of thermal expansion between PBT and SUS430, but these strains are absorbed by the non-conductive non-magnetic parts 4, 8, 10, and 18 made of highly elastic PBT. In addition, the temperature at the time of injection of PBT is lower than the temperature at which metals are melted, and the first and second magnetic portions 3 and 5 of the first sensor ring 2 and the third, fourth and fifth magnetic properties of the second sensor ring 6 are magnetic. The distortion of the parts 7, 9 and 11 is not so great. Thus
Residual stress is unlikely to occur in the first, second, third, fourth, fifth magnetic parts 3, 5, 7, 9, 11, the guides 12, 15 and the spacers 13, 16. For this reason, the changes in the inductances of the coils 14 and 17 are not small, and variations hardly occur. Therefore, a high and stable detection output can be maintained.

Further, the PBT has a relatively low material cost and processing cost, and the first and second magnetic portions 3 and 5 of the first sensor ring 2 and the third, fourth and fifth magnetic portions of the second sensor ring 6 made of SUS430 are used. 7, 9 and 11 are easily joined by resin molding. Therefore, it is possible to reduce the cost of parts of the first sensor ring 2 and the second sensor ring 6, and hence the manufacturing cost of the torque sensor.

Further, since PBT has excellent heat resistance and impact resistance, it becomes a torque sensor excellent in heat resistance and impact resistance.

Therefore, the torque sensor of the first embodiment has a large detection output, can be manufactured at low cost, can secure stable steering performance, and can exhibit stable quality.

The same effect can be obtained by using PPS as the non-conductive non-magnetic material. Further, since PPS has a thermal expansion coefficient similar to that of ferritic stainless steel, it is possible to prevent separation between the non-conductive non-magnetic portion made of PPS and the magnetic portion made of ferritic stainless steel. Further, alumina can be adopted as the non-conductive non-magnetic material. In this case, the torque sensor has excellent heat resistance.

(Second Embodiment) As shown in FIG. 8, the main mechanical structure of the torque sensor of the second embodiment is the same as that of FIG. 1, and the same mechanical structure as that shown in FIG. The same reference numerals are used for, and the description thereof will be omitted.

While the torque sensor of the first embodiment has two coils, this torque sensor has only one coil 14 like the conventional torque sensor.

Therefore, in this torque sensor, the reliability of the detected value is inferior to that of the torque sensor of the first embodiment, and the change in inductance is small. However, in this torque sensor, like the torque sensor of the first embodiment, since the non-conductive non-magnetic portion 8 is made of PBT which is a non-conductive non-magnetic material, no eddy current is generated in the non-conductive non-magnetic portion 8. In addition, it neither magnetizes nor contains eddy currents.
Therefore, in this torque sensor, the change in the inductance of the coil 14 does not decrease, and a higher detection output can be obtained than in the conventional torque sensor shown in FIGS. 10 and 11.

(Third Embodiment) As shown in FIG. 9, the main mechanical structure of the torque sensor of the third embodiment is similar to that of FIG. 1, and the same mechanical structure as that shown in FIG. The same reference numerals are used for, and the description thereof will be omitted.

In this torque sensor, as shown in FIG. 9, the first sensor ring 32 as the first magnetic body is press-fitted into the input shaft 91. As a result, the first sensor ring 32 is not magnetically separated from the input shaft 91. The first sensor ring 32 has an input shaft 91.
From the side, a cylindrical first magnetic portion 33, a cylindrical first non-conductive non-magnetic portion 34, and a cylindrical second magnetic portion 35.
Consists of. The first magnetic part 33 and the second magnetic part 35 are made of SUS.
430, and the first non-conductive non-magnetic portion 34 is made of PBT as a non-conductive non-magnetic material.

The first and second magnetic portions 3 of the first sensor ring 32
A large number of rectangular tooth portions 33a, 35a as comb-shaped first protrusions are formed on the outer peripheral surfaces of 3, 35. The first non-conductive non-magnetic portion 34 of the first sensor ring 32 has the first and second magnetic portions 33 and 35 embedded therein. Tooth 33
a and 35a are exposed from the first non-conductive non-magnetic portion 34, and the tooth gap between the tooth portions 33a and 35a is not exposed from the first non-conductive non-magnetic portion 34.

A holder 50 made of SUS430 is press-fitted onto the output shaft 92, and a second sensor ring 36 as a second magnetic body is press-fitted above the holder 50. The second sensor ring 36 includes, from the input shaft 91 side, a cylindrical third magnetic portion 37, a cylindrical second non-conductive non-magnetic portion 38, and a cylindrical fourth magnetic portion 39. The third and fourth magnetic parts 37 and 39 are made of SUS430, and the second non-conductive non-magnetic part 38 is made of PBT.

The third and fourth magnetic portions 3 of the second sensor ring 36
A large number of rectangular tooth portions 37a, 39a as comb-shaped second protrusions are formed on the inner peripheral surfaces of 7, 39. The second non-conductive non-magnetic portion 38 of the second sensor ring 36 has the third and fourth magnetic portions 37 and 39 embedded therein. Tooth 37
a and 39a are exposed from the second non-conductive non-magnetic portion 38, and the tooth gap between the tooth portions 37a and 39a is not exposed from the second non-conductive non-magnetic portion 38. In addition, the tooth portions 33a and 35a of the first and second magnetic portions 33 and 35 and the tooth portion 3 of the third and fourth magnetic portions 37 and 39.
The relationship with 7a and 39a is the same as in the first embodiment.

Further, two sets of guides 42 and 45 made of SUS430 are separated by a separator 48 made of PBT. The guides 42, 45 and the separator 48 are the third
A magnetic body 65 is formed, and coils 44 and 47 are provided in the guides 42 and 45, respectively. This guide 42,
The 45 and the separator 48 also have a cylindrical shape that extends in the circumferential direction surrounding the torsion bar 90 and cover the outer peripheral surface of the second sensor ring 36.

Then, the first magnetic portion 33 and the third magnetic portion 3
7, the guide 42 and the input shaft 91 form one magnetic circuit. Further, the second magnetic portion 35, the fourth magnetic portion 39, the guide 45, the output shaft 92, and the input shaft 91 form another magnetic circuit. Other configurations are similar to those of the first embodiment.

The torque sensor of the third embodiment also forms two magnetic circuits as shown in FIG.
In addition, the first non-conductive non-magnetic portion 34 and the second non-conductive non-magnetic portion 3
8 and the separator 48 are PBT which is a non-conducting non-magnetic material.
Consists of. Therefore, the torque sensor of the third embodiment can also obtain the same operation and effect as the torque sensor of the first embodiment.

In the torque sensor of the first embodiment, the first sensor ring 2 as the first magnetic body is composed of two magnetic parts 3 and 5 and one non-conductive non-magnetic part 4. The second sensor ring 6 as a two magnetic body is composed of three magnetic parts 7, 9, 11 and two non-conductive non-magnetic parts 8, 10, and the third magnetic body 60 is a guide 12 as a magnetic part. 1
5 and spacers 13 and 16 are two in total, one separator 18 is a non-conductive non-magnetic portion, and coil 1
There are two 4 and 17. Further, in the torque sensor of the third embodiment, the first sensor ring 32 as the first magnetic body is used.
Are two magnetic parts 33 and 35 and one non-conductive non-magnetic part 3
And a second sensor ring 3 as a second magnetic body.
6 is composed of two magnetic parts 37 and 39 and one non-conductive non-magnetic part 38, and there are a total of two guides 42 and 45 as the magnetic parts of the third magnetic body 65. There is one separator 48 as a part, and two coils 44 and 47. However, the above embodiment is an exemplification, and the present invention can be implemented in a mode in which various modifications are made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a torque sensor according to a first embodiment.

FIG. 2 is an enlarged vertical sectional view of the torque sensor according to the first embodiment.

FIG. 3 relates to the torque sensor according to the first embodiment and is indicated by II in FIG.
It is an I-III arrow sectional view.

FIG. 4 relates to the torque sensor of the first embodiment, and is the IV of FIG.
It is a IV-IV cross-sectional view.

FIG. 5 is a partial cross-sectional view of a torque sensor obtained by modifying the first embodiment.

FIG. 6 is a second torque sensor according to a modification of the first embodiment.
It is a perspective view of a sensor ring.

FIG. 7 is a block diagram of an I / F circuit according to the torque sensor of the first embodiment.

FIG. 8 is a vertical sectional view of a torque sensor according to a second embodiment.

FIG. 9 is a vertical sectional view of a torque sensor according to a third embodiment.

FIG. 10 is a vertical cross-sectional view of a conventional torque sensor.

FIG. 11 is an enlarged vertical sectional view of a conventional torque sensor.

[Explanation of symbols]

90 ... Torsion bar 91 ... 1st shaft (input shaft) 92 ... 2nd shaft (output shaft) 2, 32 ... 1st magnetic body (1st sensor ring) 6, 36 ... 2nd magnetic body (2nd sensor ring) 3a, 5a, 33a, 35a ... Tooth portion (first protrusion) 7a, 9a, 11a, 37a, 39a ... Tooth portion (second protrusion) 14, 17, 44, 47 ... Coil 60, 65 ... Third magnetic body 3 5, 7, 9, 11, 12, 13, 15, 16, 3
3, 35, 37, 39, 42, 45 ... Magnetic part 4, 8, 10, 18, 34, 38, 48 ... Non-electric non-magnetic part

Claims (8)

[Claims] 1. A torsion bar extending in the axial direction, a first shaft connected to one end of the torsion bar and coaxial with the torsion bar, and connected to the other end of the torsion bar, the torsion bar and A second shaft that is coaxial with the first shaft, a first magnetic body that is fixed to the first shaft and has a first protrusion, and a second protrusion that is fixed to the second shaft and faces the first protrusion. A second magnetic body having, a coil facing the first magnetic body and the second magnetic body, and a coil that surrounds the coil and forms a magnetic circuit with the first magnetic body and the second magnetic body. The coil has three magnetic bodies, and the coil changes its inductance in response to a change in the facing area of the first protrusion and the second protrusion due to the twist acting on the torsion bar, and the torque is changed based on the inductance. In the torque sensor for detecting, the first magnetic body and the front The second magnetic body has a cylindrical shape extending in the circumferential direction surrounding the torsion bar, and the first protrusion is formed on the outer periphery of the first magnetic body in a comb-tooth shape.
The second protrusion, which faces the first protrusion in the radial direction, is formed in a comb-teeth shape on the inner circumference of the second magnetic body, and the first magnetic body, the second magnetic body, and the third magnetic body are formed. At least one of the bodies has a magnetic portion made of a magnetic material axially magnetically divided by a non-conductive non-magnetic portion made of a non-conductive non-magnetic material. 2. The first magnetic body comprises two or more cylindrical magnetic portions that are magnetically divided and fixed with respect to the first axis, and a non-conductive member integrally provided between the magnetic portions. The second magnetic body includes a non-magnetic portion, and the second magnetic body includes three or more cylindrical magnetic portions and a non-conductive non-magnetic portion integrally provided between the magnetic portions. The two adjacent magnetic parts face one magnetic part of the first magnetic body in the radial direction, and the third magnetic body is provided integrally with two or more magnetic parts between the magnetic parts. And a non-conductive non-magnetic portion, wherein each magnetic portion of the third magnetic body faces two adjacent magnetic portions of the second magnetic body in the radial direction. 1. The torque sensor according to 1. 3. The first magnetic body and the third magnetic body have two magnetic portions sandwiching one non-conductive non-magnetic portion, and the second magnetic body has three magnetic portions sandwiching two non-conductive non-magnetic portions. The torque sensor according to claim 2, further comprising: 4. The first magnetic body is composed of two cylindrical magnetic portions fixed to the first shaft without being magnetically divided, and a non-conductive body integrally provided between the magnetic portions. The second magnetic body is composed of two cylindrical magnetic portions and a non-conductive non-magnetic portion integrally provided between the magnetic portions.
Each of the magnetic parts of the second magnetic body faces one of the magnetic parts of the first magnetic body in the radial direction, and the third magnetic body is integrated with the two magnetic parts between the magnetic parts. 7. A non-conductive non-magnetic portion provided, wherein each of the magnetic portions of the third magnetic body faces one of the magnetic portions of the second magnetic body in the radial direction. 1. The torque sensor according to 1. 5. The first protrusion or the second protrusion in which the magnetic portions face each other.
A protrusion, and the first protrusion or the second protrusion is exposed from the non-conductive non-magnetic portion, and the tooth gap between the first protrusion or the second protrusion is not exposed from the non-conductive non-magnetic portion. The torque sensor according to claim 1, 2, 3, or 4. 6. The torque sensor according to claim 1, wherein the non-conductive non-magnetic material is resin. 7. The torque sensor according to claim 6, wherein the non-conductive non-magnetic material is polyphenylene sulfide. 8. The torque sensor according to claim 1, wherein the non-conductive non-magnetic material is ceramics.