JP2001318012A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor free from dispersion of torque detecting performance without complifying its structure. SOLUTION: This sensor has the first molded members 21 having an axial center same to the first shaft and rotated together therewith, and the second molded members 23 having an axial center same to the second shaft and rotated together therewith. The respective members 21, 23 are juxtaposed with an equal space along a circumferential direction of a cylinder having an axial center same to the both shafts, and have plural detection parts 21a, 23a of the same outer shape. Signals in response to transmission torques by the both shafts are output in response to a relative positional change between the first detection part 21a of the first molded member 21 and the second detection part 23a of the second molded member 23 caused by elastic relative rotation of the coaxial center of the both shafts. Positioning marks M1, M2 are provided in the molded members 21, 23 respectively. When the both shafts are located in a detection origin position where the both shafts are not rotated relatively, the mark M1 of the member 21 and the mark M2 of the member 23 are arranged in fixed positions preliminarily determined each other along the circumferential direction of the cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor suitable for detecting a steering torque in, for example, a power steering device for applying a steering assist force according to the steering torque.

[0002]

2. Description of the Related Art For example, in a power steering apparatus for a vehicle, when the rotation of a steering wheel is transmitted from an input shaft to a wheel via an output shaft, a steering torque transmitted from the input shaft to the output shaft is shown in FIG. The torque sensor 100. The steering assist force is applied according to the magnitude of the detected torque.

In the torque sensor 100, an input shaft 102 and an output shaft 103 are connected via a torsion bar 104, and relatively elastically rotate according to a transmission torque. A plurality of teeth 105a having the same outer shape are provided on an end surface of a first detection ring 105 made of a magnetic material attached to the input shaft 102 and an end surface of a second detection ring 106 made of a magnetic material attached to the output shaft 103, respectively. 106a are provided so as to be arranged in parallel at equal intervals along the circumferential direction of the cylinder coaxial with both shafts 102 and 103. It is held by a coil holder 107 made of a magnetic material inserted into the housing 101. When the coil 108 generates a magnetic flux, a magnetic circuit including the first detection ring 105, the second detection ring 106, and the coil holder 107 as constituent members is configured. Due to the relative rotation of both shafts 102 and 103, the relative position between one tooth 105a and the other tooth 106a changes, and the area of one tooth 105a and the other tooth 106a facing each other changes. The change in the area changes the magnetic resistance of the magnetic circuit. A torque detection circuit is provided which outputs a signal corresponding to the torque transmitted by both shafts 102 and 103 based on electromagnetic induction due to the change in the magnetic resistance.

[0004]

Conventionally, when both shafts 102 and 103 are at the detection origin position where they are not relatively rotating, each tooth 105a of the first detection ring 105 and each tooth 105a of the second detection ring 106 The teeth 106a are arranged so as to face one to one. However, the first detection ring 105
Of each tooth 105a of the second detection ring 106
There was no criterion for determining whether to oppose 06a. Therefore, the detection rings 105 and 106 could not be attached to the shafts 102 and 103 such that the respective teeth 105a of the first detection ring 105 faced the specific teeth 106a of the second detection ring 106. In addition, each detection ring 1
Each tooth 105a, 10
The dimensions of 6a are not uniform. For this reason, there is a problem in that the torque detection performance varies among a plurality of torque sensors due to the difference in the relative mounting positions of the two detection rings 105 and 106.

An object of the present invention is to provide a torque sensor that can solve the above-mentioned problem.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a first shaft, a second shaft coaxially and resiliently connected to the first shaft so as to be relatively rotatable, and a coaxial and coaxial shaft with the first shaft. A first shaping member mounted for rotation and a second shaping member mounted coaxially and co-rotatably with the second shaft, the first shaping member being a cylinder coaxial with both shafts; Are formed in parallel with each other at equal intervals along the circumferential direction, and are formed so as to have a plurality of first detecting portions having the same outer shape with each other, and the second forming members are formed at equal intervals along the circumferential direction of the cylinder. In parallel with each other, and are formed so as to have a plurality of second detectors having the same outer shape with each other, and the two detectors are used in accordance with a change in the relative position between the first detector and the second detector due to the relative rotation of both shafts. For transmission torque In a torque sensor capable of outputting a corresponding signal, a positioning mark is provided on each molded member, and when the two shafts are at a detection origin position where the shafts are not relatively rotating, the mark of the first molded member and the mark of the second molded member are provided. The marks are arranged at predetermined fixed positions with respect to each other in the circumferential direction of the cylinder. According to the configuration of the present invention, when the two shafts are at the detection origin position, the specific first detection unit and the specific second detection unit are positioned on the circumference of the cylinder with reference to the positioning marks provided on the respective molded members. Molded members can be attached to each shaft so that they are located at predetermined fixed positions with respect to each other in the direction. Therefore, even if the dimensions of the respective detecting units are not uniform due to the tolerance, the relative position between the specific first detecting unit and the specific second detecting unit in the circumferential direction of the cylinder is determined between the plurality of torque sensors. Non-uniformity can be prevented. Thereby, the torque detection performance based on the relative position change of the two detection units due to the relative rotation of the two shafts can be made uniform.

Preferably, each detecting portion is formed by molding, and each mark is provided by molding at the same time as forming each detecting portion. According to this configuration, a mark can be accurately and easily provided at a fixed position in each molded member.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A torque sensor 1 according to a first embodiment shown in FIG. 1 detects a steering torque in a power steering device of a vehicle. The torque sensor 1 includes a housing 2, a first shaft 3, and a second shaft 4. One end of the housing 2 has a steering column 5
Are connected. The outer periphery of the first shaft 3 is supported by the inner periphery of the steering column 5 via a bush 12. The outer periphery of the second shaft 4 is supported by bearings 13 and 14 by the inner periphery of the housing 2.

The steering shaft 6 has one end connected to one end of the first shaft 3 by a pin 8 and the other end connected to a steering wheel (not shown). The torsion bar 7 is inserted into the first shaft 3 and the second shaft 4. One end of the torsion bar 7 is connected to one end of the first shaft 3 by the pin 8, and the other end is connected to the second shaft 4 by a pin 10. Thus, the first shaft 3 and the second shaft 4 can be relatively elastically rotated coaxially by the torsion of the torsion bar 7 according to the steering resistance.

The rotation of the second shaft 4 is transmitted to the wheels via, for example, a rack and pinion type steering gear or the like, so that the wheels are steered. A worm wheel 15 is attached to the outer periphery of the second shaft 4. The worm wheel 15 meshes with a worm 16 attached to an output shaft of a motor for generating a steering assist force.

A first detection ring (first molded member) 21 made of a magnetic material is mounted on the first shaft 3 so as to be coaxial and rotate together. On the second shaft 4,
A second detection ring (second molded member) 23 made of a magnetic material is attached so as to rotate coaxially with the second detection ring. One end face of the first detection ring 21 and the other end face of the second detection ring 23 are arranged to face each other. As shown in FIGS. 2A and 2B, the first detection ring 21
A plurality of teeth having the same outer shape (first detection unit)
21a are provided in parallel at equal intervals along the circumferential direction of the cylinder coaxial with both shafts 3 and 4.
The other end of the first detection ring 21 is a small diameter portion 21b having a smaller outer diameter than the one end. On the other end surface of the second detection ring 23, a plurality of teeth (second detection portions) 23a having the same outer shape are arranged at equal intervals along the circumferential direction of a cylinder coaxial with both shafts 3 and 4. It is provided so as to be parallel. Each tooth 21a, 23a is molded, for example,
The respective detection rings 21 and 23 are formed so as to have the respective teeth 21a and 23a by die forging or casting.

A first coil holder 31 made of a magnetic material and a second coil holder 32 made of a magnetic material are inserted into the inner periphery of the housing 2. The first coil holder 31
The first coil 33 is inserted into the inner periphery of the second coil holder 32, and the second coil 34 is inserted into the inner periphery of the second coil holder 32.

An annular distance piece 51 is arranged between the first coil holder 31 and the second coil holder 32. The first and second coil holders 31, 3
The distance piece 2 and the distance piece 51 are sandwiched by a retaining ring 55 fitted on the inner periphery of the housing 2 and the inner surface 2 d of the housing 2 via a spring 60.

The coils 33 and 34 are connected to a printed circuit board 41 mounted on the outer surface of the housing 2 via wiring. The torque detection circuit shown in FIG. 3 is formed on the printed board 41. That is, the first coil 3
3 is connected to an oscillator 46 via a resistor 45, the second coil 34 is connected to the oscillator 46 via a resistor 47, and the coils 33 and 34 are connected to a differential amplifier circuit 48. As a result, the first coil 33 generates a magnetic flux that passes through the first detection ring 21, the second detection ring 23, and the first coil holder 31, so that the first detection ring 21, the second detection ring 23, and the first coil A first magnetic circuit including the holder 31 as a constituent member is configured. Also, the second coil 34
Generates a magnetic flux that passes through the first detection ring 21 and the second coil holder 32, thereby generating a second magnetic field including the first detection ring 21 and the second coil holder 32 as constituent members.
A magnetic circuit is configured.

The transmission of torque from the first shaft 3 to the second shaft 4 causes the torsion bar 7 to be elastically twisted, and the two shafts 3, 4 to rotate relative to each other. Accordingly, the first detection ring 21 and the second detection ring 23 rotate relatively, and the relative positions of the teeth 21a of the first detection ring 21 and the teeth 23a of the second detection ring 23 change. A signal corresponding to the transmission torque is output according to the relative position change.
In other words, both teeth 23a, 23
The area of b facing each other changes. Due to this area change, the magnetic resistance of the first magnetic circuit changes. The output of the first coil 33 changes based on the change in the magnetic resistance.
Thereby, the transmission torque corresponding to the output is detected. The outer diameter of the small diameter portion 21b is set such that the magnetic resistance in the first magnetic circuit and the magnetic resistance in the second magnetic circuit are equal to each other in a state where no steering torque is applied. As a result, the output fluctuation of the first coil 33 due to the temperature fluctuation becomes equal to the output fluctuation of the second coil 34 due to the temperature fluctuation. Therefore, the output fluctuation is canceled by the differential amplifier circuit 48 and is based on the change in the magnetic resistance in the first magnetic circuit. Temperature fluctuation of the detected value of the transmission torque can be compensated. By driving the motor according to a signal corresponding to the transmission torque output from the differential amplifier circuit 48, a steering assist force is applied via the worm 16, the worm wheel 15, and the second shaft 4. .

As shown in FIG. 2, each detection ring 21, 2
The first and second positioning marks M1 and M2 are
It is provided by molding at the same time as molding the teeth 21a, 23a of the detection rings 21, 23. Each mark M1,
The form of M2 is a circular stamp in the illustrated example,
It may be a figure, a character, a number, or the like of another shape, or may be a shape that protrudes from the surface of the detection rings 21 and 23 instead of the engraved shape, and may be any symbol that can be recognized for positioning. Further, the first mark M1 and the second mark M2 may have different outer shapes. In the present embodiment,
The first mark M1 is provided between two adjacent teeth 21a on one end surface of the first detection ring 21 so that the marks M1 and M2 do not affect the magnetic flux change. Is provided between two adjacent teeth 23 a on the other end surface of the second detection ring 23.

When the shafts 3 and 4 are at the detection origin position where they are not relatively rotated, the first mark M1 of the first detection ring 21 and the second mark M2 of the second detection ring 23 are
In the circumferential direction of the cylinder around the axis of both shafts 3, 4, they are arranged at predetermined fixed positions with respect to each other. For example, the torque sensor 1 is assembled so that the first mark M1 and the second mark M2 face each other in the shaft axis direction at the detection origin position.

According to the structure of the first embodiment, the marks M1, M provided on the respective detection rings 21, 23 are provided.
When the two shafts 3 and 4 are at the detection origin position with reference to 2, the specific teeth 21a of the first detection ring 21 and the specific teeth 23a of the second detection ring 23 are previously determined with respect to each other in the circumferential direction of the cylinder. Each of the detection rings 21 and 23 can be attached to each of the shafts 3 and 4 so as to be arranged at a predetermined fixed position. Therefore, each tooth 2
Even if the dimensions of the first and second torque sensors 1a and 23a are not uniform due to the tolerance,
The relative position between the specific tooth 21a in 1 and the specific tooth 23a in the second detection ring 23 can be prevented from becoming uneven in the circumferential direction of the cylinder. Thereby, the torque detection performance based on the relative position change of both teeth 21a and 23a due to the relative rotation of both shafts 3 and 4 can be made uniform. Further, the marks M1 and M2 are provided by molding at the same time as the teeth 21a and 23a of the detection rings 21 and 23, so that the marks M
1, M2 can be provided accurately and easily.

A torque sensor 1 'according to the second embodiment shown in FIGS. 4 to 8 detects a steering torque in a power steering device of a vehicle. The torque sensor 1 'includes a housing 2', a first shaft 3 ', and a second shaft 4'. Each of the shafts 3 ', 4' is made of a ferromagnetic material such as a steel material. The first shaft 3 'is supported by a housing 2' via a bearing 5 'and a recess 4a' formed at one end of a second shaft 4 'via a bush 6'.
Is supported by the inner circumference of. The second shaft 4 'is supported by the housing 2' via a bearing 7 '. A steering assist force is applied according to the detected torque.

A torsion bar 8 'is inserted into an axial hole 3a' formed in the first shaft 3 'and a recess 4a' in the second shaft 4 '. One end of the torsion bar 8 'is connected to the first shaft 3' so as to rotate together with the pin 9 ', and the other end is connected to the second shaft 4' via the serration 10 'so as to rotate together. Thus, the second shaft 4 'is arranged coaxially with the first shaft 3', and is elastically connected to the first shaft 3 'so as to be relatively rotatable. One end of the first shaft 3 'is connected to a steering wheel (not shown), and the other end of the second shaft 4' is connected to a steering gear such as a rack and pinion steering gear. Thus, the rotation of the steering wheel for steering is transmitted to the wheels via the first and second shafts 3 ′, 4 ′, and the steering angle changes.

The first shaft 3 'is press-fitted into a cylindrical first cylindrical member (first molded member) 11' so as to rotate coaxially with the first cylindrical member 11 '. It is connected to. The second shaft 4 'is press-fitted into a cylindrical second cylindrical member (second cylindrical member) 12' so as to be connected to the second cylindrical member 12 'so as to rotate coaxially with the second cylindrical member 12'. Have been. The second cylindrical member 12 'is provided within the housing 2' with first and second shafts 3 ',
4 'is arranged coaxially with the first tubular member 11', and covers the outer periphery of the first tubular member 11 'via a gap.

A first coil holder 31 'made of a magnetic material and a second coil holder 32' made of a magnetic material are inserted into the inner periphery of the housing 2 '. As shown in FIG. 5, each of the coil holders 31 ′ and 32 ′ has a cylindrical outer peripheral portion 3.
1a ', 32a' and outer peripheral portions 31a ', 32a'
Annular peripheral wall portion 31b 'inward from one end side of
32b ', and annular lid portions 31c' and 32c 'which are directed inward from the other ends of the outer peripheral portions 31a' and 32a '. Each coil holder 31 ', 32'
A step 2a 'formed on the inner periphery of the housing 2' and a retaining ring 53 'fitted on the inner periphery of the housing 2' are sandwiched via a leaf spring 54 ', thereby being fixed to the housing 2'. You.

The first coil 33 'held by the first coil holder 31' and the second coil holder 3 '
The second coil 34 'held by 2' is arranged in parallel along the direction of the relative rotation axis of both shafts 3 ', 4'. Both coils 33 ', 34' have the same specifications, and the conductors 33a ',
34a 'to the bobbins 33b' and 34b 'made of insulating material.
It is configured by being wound around the axis of the shaft 3 ', and is inserted into the inner periphery of each of the coil holders 31', 32 '. Each coil holder 31 ', 32' and coil 3
3 'and 34' are arranged so as to surround the outer periphery of the second cylindrical member 12 'with a gap therebetween. Each coil 33 ', 3
4 'constitutes a torque detecting circuit as described later, and generates a magnetic flux so as to generate an alternating magnetic field.

The first cylindrical member 11 'is made of a magnetic material, surrounds the outer periphery of the first shaft 3', and
It has a magnetic flux passing portion disposed at a position where the generated magnetic flux passes through 3 'and 34'. An upper opening 41 'and a plurality of lower openings 42' are respectively formed in the magnetic flux passage portion as first detecting portions. As shown in FIG. 6 and FIG.
1 'are arranged in parallel at equal intervals along the circumferential direction of a cylinder coaxial with both shaft feet 3', 4 '. The lower openings 42 'are juxtaposed at equal intervals along the circumferential direction of a cylinder coaxial with both shaft feet 3', 4 '. Each opening 4
The outer shapes of 1 'and 42' are identical to each other, and in this embodiment, have a shape along a quadrilateral having an edge parallel to the shaft axis direction and an edge parallel to the shaft circumferential direction. The upper opening 41 'and the lower opening 42' are arranged side by side at intervals along the shaft axis direction. Each opening 41 ', 4
The circumferential dimension S1 'of 2' is larger than the circumferential dimension S2 'of the magnetic flux passage between the openings 41' and 42 '.

The opening 4 is provided between the inner periphery of the magnetic flux passage of the first cylindrical member 11 'and the outer periphery of the first shaft 3'.
An annular gap δ leading to 1 ′, 42 ′ is formed.
In the present embodiment, the circumferential groove 3 is formed on the outer circumference of the first shaft 3 '.
a 'is formed, and a first groove is formed on the outer periphery of both edges of the peripheral groove 3a'.
The inner periphery of both peripheral edges of the cylindrical member 11 'is press-fitted, and a gap δ is formed between the bottom surface of the peripheral groove 3a' and the inner periphery of the first cylindrical member 11 '. An opening 4 is provided between both ends δ ′ and δ ″ of the gap δ in the direction of the relative rotation axis of the shafts 3 ′ and 4 ′.
1 'and 42' are arranged to enhance the effect of blocking magnetic flux leakage, which will be described later, and reduce the pressure input to the first cylindrical member 11 'of the first shaft 3'.

The second tubular member 12 'is made of a conductive non-magnetic material, surrounds the magnetic flux passage of the first tubular member 11', and generates the magnetic flux generated by the coils 33 'and 34'. It has a magnetic flux regulation part arranged at a passage position. A first opening 43 'and a second opening 4
4 'is formed in each case. The first opening 4
The 3 'and the second opening 44' are arranged at an interval in the shaft axis direction. The first openings 43 '
Both shaft fts 3 ', 4' are arranged in parallel at equal intervals along the circumferential direction of the cylinder coaxial. Those second openings 44 '
Are arranged in parallel at equal intervals along the circumferential direction of the cylinder coaxial with both shaft feet 3 ', 4'. Each opening 43 ', 4
The outer shapes of 4 ′ are the same as each other, and in the present embodiment, have a shape along a quadrilateral having an edge parallel to the shaft axis direction and an edge parallel to the shaft circumferential direction. The first coil 33 '
Is disposed at a position where a magnetic flux passing through each first opening 43 'is generated, and the second coil 34' is disposed at a position where a magnetic flux passing through each second opening 44 'is generated.

Each of the openings 41 ', 42', 43 ', 44' is molded. For example, the openings 4 'are formed by pressing a pipe material forming the cylindrical members 11', 12 'using a mold.
1 ', 42', 43 ', 44' parts are punched out,
The cylindrical members 11 'and 12' are formed by casting to have openings 41 ', 42', 43 'and 44'.

As shown in FIG. 5, the dimensions of the openings 43 'and 44' in the axial direction of the shaft are different from those of the coils 33 'and 3'.
4 'and the coil holders 31', 3 '
2 ', the first opening 43' is arranged between both ends of the first coil holder 31 ', the second opening 44' is arranged between both ends of the second coil holder 32 ', and the first coil 33''Is disposed between both ends of the first opening 43', and the second coil 34 'is disposed between both ends of the second opening 44'. Thereby, the first shaft 3 ', the second shaft 4', the first shaft
Even if the relative position in the axial direction of the coil 33 ', the second coil 34', and the second tubular member 12 'fluctuates due to manufacturing tolerances and assembly tolerances, the relative rotational axis direction of the two shafts 3', 4 '. Openings 43 'and 44' are connected to coil 3
3 ', 34' can be arranged at the passing position of the generated magnetic flux. Therefore, fluctuation due to the tolerance of the magnetic flux passing through the magnetic flux passing portion can be eliminated, and a decrease in detection accuracy can be prevented.

Openings 43 ', 4 in the shaft radial direction
The openings 43 'and 44' and the first detection portion 4 'are changed so that the overlapping area of the magnetic flux passage portion of the first cylindrical member 11' changes according to the relative rotation of the shafts 3 'and 4'. The parts are arranged so as to partially overlap in the radial direction of both shafts 3 ', 4'. That is, as shown in FIG. 7, in the shaft axis direction, upper and lower openings 41 ′ and 42 ′ constituting each first detection unit are respectively provided with first and second openings 43 ′ constituting each second detection unit. 44 'are longer than each. The first opening 43 'is disposed between both ends of the upper opening 41' in the shaft axis direction in the relative rotation range of the shafts 3 'and 4' corresponding to the torque detection range, and the upper opening 41 'in the shaft radial direction. Overlaps with a single edge 41a 'along the shaft axis direction.
The second opening 44 'is disposed between both ends of the lower opening 42' in the axial direction of the shaft in the relative rotation range of the shafts 3 'and 4' corresponding to the torque detection range, and the lower opening 42 'in the shaft radial direction. Overlaps with a single edge 42a 'along the shaft axis direction.

When both shafts 3 ', 4' are at the detection origin position, that is, when the steering angle is zero, the overlapping area between the first opening 43 'and the magnetic flux passing portion is equal to the second opening 44' and the magnetic flux passing portion. And the overlapping area is equal. 6 and 7
As shown in FIG. 7, when both shafts 3 ', 4' are at the detection origin position where they are not relatively rotated, one edge 41a 'along the shaft axis direction in each upper opening 41' is formed in each first opening 43 '. One edge 42a 'along the shaft axis direction at each lower opening 42' is disposed so as to overlap with the center along the shaft axis direction in the radial direction, and the center 42 along the shaft axis direction at each second opening 44 'at the radial direction. Are arranged so as to overlap each other. Each opening 43 ', 4
The circumferential dimension P1 'of 4' is smaller than the circumferential dimension S1 'of each opening 41', 42 'and the circumferential dimension S2' of the magnetic flux passage between the openings 41 ', 42'. .

The first opening 4 in the shaft radial direction
The overlapping area between 3 ′ and the magnetic flux passage portion is the same for both shafts 3 ′,
The first opening 43 'and the upper opening 41' are arranged in a relative arrangement so that the first opening 43 'and the upper opening 41' increase when the 4 'rotates relative to one direction and decrease when the shafts 3' and 4 'rotate relative to each other. Have been. Also, the second opening 4 in the shaft radial direction
The overlapping area of 4 ′ and the magnetic flux passage portion is the same for both shafts 3 ′,
The second opening 44 'and the lower opening 42' are positioned relative to each other so as to decrease when the shaft 4 'rotates relative to one direction and increase when the shafts 3' and 4 'rotate relative to each other in the other direction. Have been. That is, each second opening 44 'is arranged between the first openings 43' in the circumferential direction, and the edge 41a 'of the upper opening 41' overlapping the first opening 43 'and the lower opening 42 overlapping the second opening 44'. The edge 42a 'is located on the opposite side to the center of the openings 41', 42 'on the first detecting portion side in the circumferential direction of the shaft. When the shafts 3 'and 4' rotate relative to each other, the absolute value of the change in the overlapping area between the first opening 43 'and the magnetic flux passing portion and the absolute value of the change in the overlapping area between the second opening 44' and the magnetic flux passing portion. The values are equal to each other.

As shown by a two-dot chain line β in FIG. 5, the magnetic flux generated by the first coil 33 '
1 ', the first opening 43' of the second tubular member 12 ', and the magnetic flux passing portion of the first tubular member 11', thereby passing through the first coil holder 31 'and the first tubular member 11'. A first magnetic circuit including the magnetic flux passage as a component is configured.
Further, the magnetic flux generated by the second coil 34 ′ is generated by the second coil holder 32 ′, the second opening 44 ′ of the second tubular member 12 ′,
By passing through the magnetic flux passage of the tubular member 11 ', a second magnetic circuit including the second coil holder 32' and the magnetic flux passage of the second tubular member 12 'as constituent elements is formed.

In the above configuration, the opening constituting the first detecting portion formed in the magnetic flux passage portion of the first cylindrical member 11 'made of a magnetic material by the relative rotation of the two shafts 3', 4 'during torque transmission. The relative position between 41 ', 42' and the openings 43 ', 44' forming the second detecting portion formed in the magnetic flux regulating portion of the second cylindrical member 12 'made of conductive non-magnetic material changes. I do. A signal corresponding to the torque transmitted by both shafts 3 ', 4' is output in accordance with the relative positions of the first detection units 41 ', 42' and the second detection units 43 ', 44'. That is, the overlapping area between the openings 43 'and 44' and the magnetic flux passage in the radial direction of the second detector changes according to the relative rotation of the shafts 3 'and 4'. Since the first cylindrical member 11 'is made of a magnetic material and the second cylindrical member 12' is made of a non-magnetic material, the change in the overlapping area changes the magnetic flux passing through the magnetic flux passage. Further, the magnetic flux reaching the magnetic flux passage portion is also blocked by the eddy current generated in the conductive first cylindrical member 11 'in the alternating magnetic field generated by the magnetic flux generated in the coils 33' and 34 '. Thus, the magnetic flux passing through the magnetic flux passing portion can be changed according to the change in the overlapping area. The change in the area corresponds to both shafts 3 'corresponding to the transmission torque,
4 'corresponds to the relative rotation. The outputs of the coils 33 ′ and 34 ′ are changed by electromagnetic induction based on the change of the magnetic flux, and the transmission torque is detected based on the change of the coil output.

In the above configuration, when the two shafts 3 'and 4' rotate relative to each other in one direction during torque transmission, the overlapping area between the first opening 43 'and the magnetic flux passage increases according to the relative rotation amount. However, the overlapping area between the second opening 44 'and the magnetic flux passage portion is reduced. When the shafts 3 'and 4' rotate relative to each other in the other direction during torque transmission, the overlapping area between the first opening 43 'and the magnetic flux passage decreases according to the relative rotation amount, and the second opening 44' The overlapping area with the magnetic flux passage increases. The magnetic flux passing through the magnetic flux passage changes according to the change of each overlapping area. Also, both shafts 3 ', 4'
At the time of relative rotation, the absolute value of the change in the overlapping area between the first opening 43 'and the magnetic flux passage portion and the second opening 4'
The absolute value of the change in the overlapping area between the magnetic flux passing portion 4 'and the magnetic flux passage portion is made equal to each other. Therefore, the change in the magnetic flux passing through the magnetic flux passage portion according to the change in the overlapping area between the first opening 43 'and the magnetic flux passage portion, and the change in the magnetic flux passage according to the change in the overlap area between the second opening 44' and the magnetic flux passage portion. The torque transmitted by both shafts 3 ', 4' can be detected based on the difference from the change in the magnetic flux passing through the section, and the torque detection sensitivity is increased. Further, the torque corresponding to the relative rotation amount can be detected both when the shafts 3 ′ and 4 ′ rotate relatively in one direction and when the shafts rotate relatively in the other direction. In addition, when the temperature fluctuates, the magnetic flux passing through the magnetic flux passing portion overlapping the first opening 43 'and the magnetic flux passing through the magnetic flux passing portion overlapping the second opening 44' change by the same amount. By detecting the torque based on the difference, the fluctuation of the detected torque due to the temperature fluctuation can be offset. Further, since an annular gap δ is formed between the inner circumference of the magnetic flux passage portion of the first cylindrical member 11 ′ made of a magnetic material and the outer circumference of the first shaft 3 ′ made of a ferromagnetic material, Leakage of magnetic flux from the magnetic circuit around 33 ', 34' to the first shaft 3 'can be blocked by the gap δ. Since the first cylindrical member 11 'and the first shaft 3' are separate members, the first cylindrical member 11 '
As the first shaft 3 ', a member that satisfies the mechanical characteristics required as a structural member for transmitting torque can be selected as a member that satisfies the magnetic characteristics required for forming a magnetic circuit. it can. Further, by press-fitting the first shaft 3 'into the first cylindrical member 11', a member for fixing the first cylindrical member 11 'to the first shaft 3' is unnecessary, and the number of parts can be reduced. . Furthermore, the first
The press-fit load is reduced by the annular gap δ between the inner circumference of the magnetic flux passage portion of the cylindrical member 11 ′ and the outer circumference of the first shaft 3 ′, and distortion of the first tubular member 11 ′ due to the press-fit load is generated. Can be prevented, and a decrease in detection accuracy can be prevented.

In this embodiment, each coil 33 ', 34'
Is connected via a wire to a printed circuit board 35 'mounted on the outer surface side of the housing 2'. A torque detection circuit shown in FIG. 8 is formed on the printed board 35 '. In that circuit, the first coil 33 'is connected to a resistor 45'
, The second coil 34 'is connected to the oscillator 46' via a resistor 47 ', and the coils 33' and 34 'are connected to a differential amplifier circuit 48'. Thereby, the torsion bar 8 'is twisted by the torque transmission between both shafts 3', 4 ', so that both shafts 3',
4 'elastically rotates relative to each other, and the overlapping area between the openings 43' and 44 'constituting the second detecting portion and the magnetic flux passing portion changes according to the transmitted torque, and the change in the overlapping area changes the magnetic flux passing portion. , The output of the first and second coils 33 ′ and 34 ′ changes. The first opening 4
Based on the output of the differential amplifier circuit 48 'corresponding to the difference between the change in the magnetic flux passing through the magnetic flux passing portion overlapping with 3' and the magnetic flux passing through the second opening 44 ', the two shafts 3' , 4 'are detected. A steering assist force is applied by an actuator (not shown) such as a motor driven in accordance with a signal corresponding to the transmission torque output from the differential amplifier circuit 48 '. A known configuration can be employed for the mechanism for applying the steering assist force.

As shown in FIG. 4 and FIG.
First and second positioning marks M, 1 'and 12', respectively.
1 'and M2' are the openings 4 of the cylindrical members 11 'and 12'.
1 ', 42', 43 ', and 44' are provided by being molded simultaneously with the molding. Each mark M1 ', M
In the illustrated example, the shape of 2 ′ is a triangular engraved shape, but may be other shapes such as figures, letters, and numbers. Also, the shape is not an engraved shape but protrudes from the surfaces of the cylindrical members 11 ′ and 12 ′. Or any symbol that can be recognized for positioning. Further, the first mark M1 'and the second mark M
The outer shape may be different from 2 ′. Further, in the present embodiment, each of the marks M1 'and M2' is formed on each of the tubular members 11 'and 1' so as not to affect the magnetic flux change.
It is provided at a position on the outer periphery of 2 'and further away from the magnetic flux passage position of the first magnetic circuit toward the steering wheel.

When both shafts 3 'and 4' are at the detection origin position where they are not relatively rotated, the first mark M1 'of the first cylindrical member 11' and the second mark M of the second cylindrical member 12 'are formed.
2 'is disposed at a predetermined fixed position with respect to each other in the circumferential direction of the cylinder coaxial with both shafts 3', 4 '. For example, the first mark M1 'and the second mark M
The torque sensor 1 is assembled so as to face 2 ′ in the shaft axis direction at the detection origin position.

According to the configuration of the second embodiment, the mark M provided on each of the cylindrical members 11 'and 12' is provided.
With reference to 1 'and M2', specific openings 41 'and 42' in the first cylindrical member 11 'and specific openings in the second cylindrical member 12' when both shafts 3 'and 4' are at the detection origin position. The cylindrical members 11 ', 12' may be attached to the shafts 3 ', 4' so that the openings 43 ', 44' are arranged at predetermined positions relative to each other in the circumferential direction of the cylinder. it can. Therefore, each opening 41 ', 4
Even if the dimensions of 2 ', 43', 44 'are not uniform due to tolerances, the specific openings 41', 42 'in the first cylindrical member 11' and the second cylindrical The relative position of the member 12 'with respect to the specific openings 43', 44 'can be prevented from becoming uneven in the circumferential direction of the cylinder. Thereby, the relative rotation between the openings 41 ', 42' of the first tubular member 11 'and the openings 43', 44 'of the second tubular member 12' due to the relative rotation of the shafts 3 ', 4' is based on the change. The torque detection performance can be made uniform. Further, the marks M1 ', M2' are connected to the openings 41 ', 42', 43 ',
The marks M1 and M2 are provided at predetermined positions on the cylindrical members 11 'and 12' by being provided by molding at the same time as 44 '.
Can be provided accurately and easily.

[0039]

According to the present invention, it is possible to provide a torque sensor having a uniform torque detection performance without complicating the structure.

[Brief description of the drawings]

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

FIG. 2 is a front view of a detection ring in the torque sensor according to the first embodiment of the present invention, and FIG.

FIG. 3 is an explanatory diagram of a circuit configuration of the torque sensor according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a torque sensor according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a torque sensor according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part of a torque sensor according to a second embodiment of the present invention.

FIG. 7 is a partial development view of a cylindrical member of the torque sensor according to the second embodiment of the present invention.

FIG. 8 is a diagram showing a torque detection circuit according to a second embodiment of the present invention.

FIG. 9 is a sectional view of a conventional torque sensor.

[Explanation of symbols]

 1, 1 'Torque sensor 3, 3' First shaft 4, 4 'Second shaft 11', 12 'Cylindrical member (molded member) 21, 23 Detection ring (molded member) 21a, 23a Teeth (detection section) 41 ', 42', 43 ', 44' Opening (detection unit) M1, M2, M1 ', M2' mark

Claims (2)

[Claims] 1. A first shaft, a second shaft coaxially and elastically connected to the first shaft so as to be relatively rotatable, and a first shaft coaxially and rotatably attached to the first shaft. A molding member, and a second molding member attached to the second shaft so as to be coaxial and rotatable with the second shaft, and the first molding member is equally spaced along a circumferential direction of a cylinder coaxial with both shafts. Are formed so as to have a plurality of first detecting portions having the same outer shape with each other, and the second formed members are arranged at equal intervals along the circumferential direction of the cylinder and have the same outer shape. It is formed to have the same plurality of second detection units, and outputs a signal corresponding to the transmission torque by both shafts according to a change in the relative position between the first detection unit and the second detection unit due to the relative rotation of both shafts. Possible In the sensor, a positioning mark is provided on each molded member, and when both shafts are at the detection origin position where they are not relatively rotating, the mark of the first molded member and the mark of the second molded member are A torque sensor, which is arranged at a predetermined fixed position with respect to each other in a circumferential direction. 2. The torque sensor according to claim 1, wherein each detecting portion is formed by molding, and each mark is provided by molding at the same time as forming each detecting portion.