JP2001281078A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor which is excellent in detection precision and detection sensitivity while its weight is reduced. SOLUTION: A cylindrical moving member 12 which moves in a shaft axis direction according to elastic/relative rotation between the first and second shafts 3 and 4, is enclosed with coils 33 and 34 which generate a magnetic flux so as to cause an alternating field. A magnetic flux pass part of magnetic material comprising at least one outer perimeter among both shafts 3 and 4 is enclosed with a magnetic-flux regulating part of non-magnetic material which has electric-continuity at the moving member 12. An overlapping area in the shaft radial direction between the magnetic-flux passing part outer perimeter continued at the edge of recessed parts 41 and 42 of the magnetic-flux pass part and openings 43 and 44 of the magnetic-flux regulating part, changes according to movement of the moving member 12 caused by the relative rotation of both shafts 3 and 4. A transmission torque of both shafts 3 and 4 is detected based on the change of passing magnetic flux at the magnetic-flux passing part, according to change in the overlapping area.

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 In a power steering apparatus for a vehicle, for example, when the rotation of a steering wheel is transmitted to wheels via a steering shaft, torque transmitted by the steering shaft is detected by a torque sensor, and the magnitude of the detected torque is increased. The steering assist force is applied accordingly.

[0003] For example, a torque sensor disclosed in Japanese Patent Application Laid-Open No. 7-198510 discloses a slider which is displaced in the shaft axis direction in accordance with the elastic relative rotation of a pair of shafts, and an induced voltage which is dependent on the displacement of the slider. And a differential transformer that generates torque, and detects the torque transmitted by both shafts based on the induced voltage.

[0004]

The above-mentioned conventional torque sensor has a problem that the weight is increased because a differential transformer is required for torque detection.

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

[0006]

SUMMARY OF THE INVENTION A torque sensor according to the present invention comprises a first shaft, a second shaft coaxially and elastically connected to the first shaft so as to be relatively rotatable, and a coaxial center between the two shafts. As a cylindrical moving member, a mechanism for interlocking the two shafts and the moving member so that the moving member moves in the shaft axis direction with respect to the two shafts in accordance with the relative rotation of the two shafts, and so as to surround the moving member. And a coil for generating a magnetic flux so as to generate an alternating magnetic field, and a magnetic flux passage portion made of a magnetic material disposed at a position where the generated magnetic flux of the coil passes by at least one outer periphery of both shafts. The moving member has a magnetic flux restricting portion made of a conductive non-magnetic material, which is arranged at a position where the generated magnetic flux of the coil passes while surrounding the magnetic flux passing portion. A concave portion is formed, an opening is formed in the magnetic flux regulating portion, and in the radial direction of the shaft, an overlapping area between the outer periphery of the magnetic flux passing portion connected to the edge of the concave portion and the opening is used for movement of the moving member due to relative rotation of both shafts. The concave portion and the opening are arranged relative to each other so that the torque transmitted by both shafts is detected based on a change in the magnetic flux passing through the magnetic flux passing portion according to a change in the overlapping area. As the magnetic material forming the magnetic flux passage portion, for example, a soft magnetic metal material having excellent magnetic properties required for forming the torque sensor can be used.
As the conductive non-magnetic material constituting the magnetic flux regulating portion, a paramagnetic material having excellent conductivity and small magnetic permeability such as aluminum can be used. In the above configuration, the moving member moves in the axial direction with respect to both shafts due to the relative rotation of both shafts during torque transmission. As a result, the overlapping state between the concave portion formed in the magnetic flux passage portion and the opening formed in the magnetic flux regulating portion of the moving member changes, so that the diameter of the shaft between the outer periphery of the magnetic flux passage portion connected to the edge of the concave portion and the opening is changed. The overlapping area in the direction changes according to the relative rotation amount of both shafts. Since the magnetic flux passage is made of a magnetic material and the moving member is made of a non-magnetic material, the magnetic flux passing through the magnetic flux passage changes due to a change in the overlapping area. Further, the magnetic flux reaching the magnetic flux passage is also blocked by an eddy current generated in the conductive moving member in the alternating magnetic field generated by the generation of the magnetic flux of the coil. Thus, the magnetic flux passing through the magnetic flux passing portion can be changed according to the change in the overlapping area. Since the change in the area corresponds to the relative rotation amount of both shafts corresponding to the transmission torque, the torque transmitted by both shafts can be detected based on the change in the magnetic flux.

When the two shafts rotate relative to each other in one direction, the moving member moves axially in one direction in accordance with the relative rotation amount, and when the shafts rotate relative to each other in the other direction,
The opening moves along a quadrilateral having a pair of edges parallel to the shaft axial direction and a pair of edges parallel to the shaft circumferential direction, wherein the opening moves in the axial direction in the other direction according to the relative rotation amount. It has a shape, and its concave portion is formed in a peripheral groove shape, and in the moving range of the moving member corresponding to the torque detection range,
One edge along the shaft circumferential direction in the concave portion is arranged so as to overlap with the opening in the shaft radial direction, and the other edge in the concave portion is arranged so as not to overlap with the opening in the shaft radial direction. Is preferred. Thereby, the opening and the concave portion can be easily formed, and the torque corresponding to the relative rotation amount can be detected both when the two shafts are relatively rotated in one direction and when the two shafts are relatively rotated in the other direction.

[0008] As the coil, a first coil and a second coil of the same specification are arranged in parallel along the shaft axis direction, and the opening is a first opening and a second coil arranged at an interval in the shaft axis direction. An opening, and as the recess, a first recess and a second recess which are arranged at an interval in the shaft axis direction, and the first coil of the first
The second coil is disposed at a position where a magnetic flux passing through the opening is generated, and the second coil is disposed at a position where a magnetic flux passing through the second opening is generated. When the moving members move in one direction due to the relative rotation of both shafts in one direction, the overlapping area with each other increases, and the moving members move in the other direction by the relative rotation of both shafts in the other direction. At this time, the moving member is arranged relative to each other so that the overlapping area is reduced, and the second opening and the outer periphery of the magnetic flux passing portion connected to the edge of the second concave portion are moved by the relative rotation of the two shafts in one direction. When the moving members move in the other direction due to the relative rotation of the two shafts in the other direction, the overlapping areas with each other increase when the moving member moves in the other direction. , Relative rotation of both shafts At the time, the absolute value of the change in the overlap area between the first opening and the outer periphery of the magnetic flux passage portion connected to the edge of the first recess, and the absolute value of the change of the overlap area between the second opening and the outer periphery of the magnetic flux passage portion connected to the edge of the second recess. The absolute value of the change in the overlapping area is made equal to each other, and the change in the passing magnetic flux of the magnetic flux passing portion connected to the edge of the first recess in accordance with the change in the overlapping area and the change in the second recess in accordance with the change in the overlapping area. It is preferable that the torque transmitted by both shafts is detected based on a difference from a change in the passing magnetic flux of the magnetic flux passing portion connected to the edge. According to this configuration, when both the shafts relatively rotate in one direction during the torque transmission and the moving member moves in one direction, the outer periphery of the magnetic flux passing portion connected to the edge of the first opening and the first recessed portion according to the amount of movement. And the overlapping area between the second opening and the outer periphery of the magnetic flux passage portion connected to the edge of the second concave portion decreases. When both shafts rotate relative to each other in the other direction during torque transmission and the moving member moves in the other direction, the overlapping area between the first opening and the outer periphery of the magnetic flux passage decreases according to the amount of movement, and the second opening and the magnetic flux The overlapping area with the outer periphery of the passage portion increases. The magnetic flux passing through the magnetic flux passage changes according to the change of each overlapping area. When the shafts rotate relative to each other, the first
The absolute value of the change in the overlap area between the opening and the outer periphery of the magnetic flux passage portion and the absolute value of the change in the overlap area between the second opening and the outer periphery of the magnetic flux passage portion are 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 and the outer periphery of the magnetic flux passage portion, and the change in the magnetic flux passing according to the change in the overlap area between the second opening and the outer periphery of the magnetic flux passage portion. The torque transmitted by both shafts can be detected based on the difference from the change in the magnetic flux passing through the section, and the torque detection sensitivity can be increased. Moreover, when the temperature fluctuates, the magnetic flux passing through the magnetic flux passing portion overlapping the first opening and the magnetic flux passing through the magnetic flux passing portion overlapping the second opening change by the same amount. , The fluctuation of the detected torque due to the temperature fluctuation can be offset.

A plurality of the first openings are formed so as to be arranged in parallel at an interval in the circumferential direction of the shaft, and a plurality of the second openings are formed so as to be arranged in parallel at an interval in the circumferential direction of the shaft. The recess is preferably provided over the entire area in the circumferential direction of the shaft, and the second recess is preferably provided over the entire area in the circumferential direction of the shaft. As a result, the change in the overlapping area between the outer periphery of the magnetic flux passage portion and the opening according to the torque change can be made as large as possible, and the torque detection sensitivity can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A torque sensor 1 shown in FIGS.
Detects the steering torque in the power steering device of the vehicle. The torque sensor 1 includes a housing 2 and
A first shaft 3 and a second shaft 4 are provided. The first shaft 3 is supported by the housing 2 via a bearing 5 and is supported by an inner periphery of a recess 4 a formed at one end of the second shaft 4 via a bush 6. 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 3 a formed in the first shaft 3 and a concave portion 4 a of the second shaft 4. One end of the torsion bar 8 is connected by a pin 9 so as to rotate with the first shaft 3, and the other end is connected through the serration 10 to rotate with the second shaft 4. This allows
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. Thereby, the rotation of the steering wheel for steering is first,
The power is transmitted to the wheels via the second shafts 3 and 4, and the steering angle changes.

A cylindrical moving member 12 is mounted on both shafts 3 and 4.
Are coaxially connected. An interlocking mechanism is configured to interlock the two shafts 3, 4 and the moving member 12 so that the moving member 12 moves in the shaft axis direction with respect to the two shafts 3, 4 according to the relative rotation of the two shafts 3, 4. ing.
That is, the pin 13b fixed to the second shaft 4 is inserted into the elongated hole 13a formed in the moving member 12 and having the longitudinal direction in the shaft axis direction so as to be relatively movable in the shaft axis direction. The second shaft 4 and the second shaft 4 are connected so as to be rotatable together and relatively movable in the axial direction of the shaft. A pin 13d fixed to the first shaft 3 is inserted into a long hole 13c formed on the second shaft 4 and having a spiral direction around a shaft axis thereof as a longitudinal direction so as to be relatively movable in the spiral direction. Thus, the moving member 12 and the first
The shaft 3 is connected so as to be relatively movable along the spiral line. When the shafts 3 and 4 are at the detection origin positions where the shafts 3 and 4 are not relatively rotated, the pins 13b and 13d are arranged at the center positions in the longitudinal direction of the long holes 13a and 13c. Accordingly, when the two shafts 3 and 4 relatively rotate in one direction, the moving member 12 moves in the axial direction in one direction according to the relative rotation amount, and when the two shafts 3 and 4 relatively rotate in the other direction. Move in the axial direction in the other direction according to the relative rotation amount.

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. 2, each of the coil holders 31 and 32 has a cylindrical outer peripheral portion 31a, 32.
a, annular peripheral wall portions 31b, 32b directed inward from one end sides of the outer peripheral portions 31a, 32a, and annular lid portions 31c, 32c directed inward from the other end sides of the outer peripheral portions 31a, 32a. It is composed of Each of the coil holders 31 and 32 includes a step 2 a formed on the inner periphery of the housing 2 and a retaining ring 5 fitted on the inner periphery of the housing 2.
3 are sandwiched by a leaf spring 54 and are thereby fixed to the housing 2.

A first coil 33 held by the first coil holder 31 and a second coil 34 held by the second coil holder 32 are connected to both shafts 3, 4.
Are arranged in parallel along the direction of the relative rotation axis. Both coils 33, 3
Reference numeral 4 denotes the same specification, which is configured by winding conductive wires 33a and 34a around bobbins 33b and 34b made of an insulating material around the shaft axis, and inserted into the inner circumference of each of the coil holders 31 and 32. The coil holders 31 and 32 and the coils 33 and 34 are arranged so as to surround the outer periphery of the moving member 12 with a gap therebetween. Each of the coils 33 and 34 forms a torque detection circuit as described later, and generates a magnetic flux so as to generate an alternating magnetic field.

The first shaft 3 is made of a magnetic material. As a result, the outer periphery of the first shaft 3 is arranged at the position where the magnetic flux generated by the coils 33 and 34 passes, and the outer periphery constitutes a magnetic flux passage portion made of a magnetic material along the cylindrical surface. In the present embodiment, the first shaft 3 is formed of a single member. However, the first shaft 3 is formed by integrating a member constituting a magnetic flux passage portion and a member constituting a portion other than the magnetic flux passage portion. May be formed.

As shown in FIGS. 2 and 3, a circumferential groove-shaped first recess 41 having edges 41 'and 41 "extending in the circumferential direction of the shaft in the magnetic flux passage portion, and an edge 42' extending in the circumferential direction of the shaft.
And a second recess 42 having a circumferential groove shape having a diameter of 42 ″. The two recesses 41 and 42 are arranged at an interval in the axial direction of the shaft, and are respectively provided over the entire area in the circumferential direction of the shaft. The dimensions of the recesses 41 and 42 are equal to each other.

The moving member 12 is made of a conductive non-magnetic material, surrounds the magnetic flux passage portion, and
A magnetic flux restricting portion is disposed at a position where the generated magnetic flux passes through 3, 34. In the present embodiment, the inner periphery of the movable member 12 and the outer periphery of the second shaft 4 relatively slide, so that the movable member 1
2 rattling is prevented. The moving member 1
A member having a small coefficient of friction, for example, Teflon (registered trademark) may be interposed between the inner periphery of the shaft 2 and the outer periphery of each of the shafts 3 and 4 in order to prevent the two from being twisted.

A plurality of first openings 43 and a plurality of second openings 44 are formed in the magnetic flux regulating portion. The first opening 43 and the second opening 44 are arranged at an interval in the shaft axis direction. The first openings 43 are arranged in parallel at equal intervals in the circumferential direction of the shaft. Those second
The openings 44 are arranged in parallel at equal intervals in the circumferential direction of the shaft. The shapes and dimensions of the openings 43 and 44 are made equal to each other. In the present embodiment, the openings 43 and 44 have a pair of edges parallel to the shaft axis direction and a pair of edges parallel to the shaft circumferential direction.
It has a shape along the side. Each of the first coils 33 is a first coil.
The second coil 34 is arranged at a position where a magnetic flux passing through each of the second openings 44 is generated.

In the radial direction of the shaft, each of the recesses 4
One edge 4 along the shaft circumferential direction at 1, 42
The overlapping area between the outer circumference of the magnetic flux passage portion connected to 1 ′ and 42 ′, in this embodiment, the outer circumferential portion between the concave portions 41 and 42 of the first shaft 3 and the openings 43 and 44, Each of the recesses 41 and 42 and each of the openings 43 and 44 are changed in accordance with the movement of the moving member 12 due to the relative rotation.
And are arranged relative to each other.

That is, as shown in FIG. 3, the axial dimension L1 of the magnetic flux passing portion between one edge 41 'of the adjacent first concave portion 41 and one edge 42' of the second concave portion 42 is: The dimension of the magnetic flux regulating portion between the one edge 43 ′ of the adjacent first opening 43 and the one edge 44 ′ of the second opening 44 is larger than the dimension L 2 in the shaft axis direction. Then, in the shaft axial movement range of the moving member 12 corresponding to the torque detection range, one edge 41 ′ of the first recess 41 along the shaft circumferential direction is arranged to overlap the first opening 43 in the shaft radial direction, Second recess 4
The second edge 42 'along the circumferential direction of the shaft in No. 2 is the second
The opening 44 is arranged so as to overlap with the shaft radial direction.

As a result, the outer periphery of the magnetic flux passage between the recesses 41 and 42 and the openings 43 and 44 overlap in the radial direction of the shaft. The first opening 43 and the outer periphery of the magnetic flux passing portion connected to one edge 41 ′ of the first concave portion 41 are moved in one direction (in FIG. 2) by the relative rotation of the shafts 3 and 4 in one direction. When moving to the right, the overlapping area with each other increases, and both shafts 3, 4
When the moving member 12 moves in the other direction (left direction in FIG. 2) due to the relative rotation in the other direction, the moving members 12 are disposed so as to reduce the overlapping area with each other. Also, the second opening 44 and the outer periphery of the magnetic flux passage portion connected to one edge 42 ′ of the second concave portion 42 are connected to the two shafts 3 and 4 when the moving member 12 moves in one direction due to relative rotation in one direction. Are arranged so that when the moving member 12 moves in the other direction due to the relative rotation of the shafts 3 and 4 in the other direction, the overlapping area with each other increases. I have.

When the shafts 3 and 4 are at the detection origin position where they are not relatively rotated, the first opening 43 and the first recess 41 are formed.
The overlapping area with the outer periphery of the magnetic flux passing portion connected to one edge 41 ′ of the second opening 44 is equal to the overlapping area of the outer periphery of the magnetic flux passing portion continuous with the second opening 44 and the outer edge 42 ′ of the second concave portion 42. Have been. Further, 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 outer periphery of the magnetic flux passage portion connected to one edge 41 ′ of the first concave portion 41 and the second Opening 44 and second recess 4
The absolute value of the change in the overlapping area with the outer periphery of the magnetic flux passage portion connected to one edge 42 'of the second pair is equal to each other.

The axial distance L3 from one edge 41 'of the first recess 41 to the other edge 41 "is equal to the first opening 4
3 is larger than the axial distance L4 to the other edge 43 ″, and the axial distance L5 from one edge 42 ′ of the second recess 42 to the other edge 42 ″ is the second opening 44. Is larger than the axial distance L6 to the other edge 44 ″ of the first concave portion 41 in the axial movement range of the moving member 12 corresponding to the torque detection range. The other edge 42 ″ of the second concave portion 42 is arranged so as not to overlap with the openings 43 and 44 in the shaft radial direction.

In the shaft axial movement range of the movable member 12 corresponding to the torque detection range, the lid portion 31c of the first coil holder 31 overlaps the magnetic flux passage portion in the shaft radial direction, and the peripheral wall portion 31b functions as the magnetic flux regulation portion. The lid portion 32c of the second coil holder 32 overlaps the magnetic flux passage portion in the shaft radial direction, and the peripheral wall portion 32b is arranged to overlap the magnetic flux regulating portion in the shaft radial direction. Disturbance is prevented.

As shown by the two-dot chain line β in FIG. 2, the magnetic flux generated by the first coil 33 passes through the first coil holder 31, the first opening 43 of the moving member 12, and the magnetic flux passage of the first shaft 3. Thus, a first magnetic circuit including the first coil holder 31 and the magnetic flux passage portion of the first shaft 3 as constituent elements is formed, and the magnetic flux generated by the second coil 34 is generated by the second coil holder 32 and the moving member 12. By passing through the second opening 44 and the magnetic flux passage of the first shaft 3,
A second magnetic circuit including the second coil holder 32 and the magnetic flux passage of the first shaft 3 as constituent elements is configured.

In the above configuration, the moving member 12 moves axially relative to the shafts 3 and 4 due to the relative rotation of the shafts 3 and 4 during torque transmission. This allows
Concave portions 41 and 42 formed in the magnetic flux passage portion;
Since the state of overlap with the openings 43 and 44 formed in the magnetic flux regulating portion 2 changes, the edges 41 ′ of the concave portions 41 and 42,
The overlapping area between the outer circumference of the magnetic flux passage portion connected to 42 'and the openings 43 and 44 changes according to the relative rotation of the shafts 3 and 4. Since the magnetic flux passing portion is made of a magnetic material and the moving member 12 is made of a non-magnetic material, the magnetic flux passing through the magnetic flux passing portion changes due to a change in the overlapping area. Further, the magnetic flux reaching the magnetic flux passage is also blocked by the eddy current generated in the conductive moving member 12 in the alternating magnetic field generated due to 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 the relative rotation of the shafts 3 and 4 corresponding to the transmission torque. The outputs of the coils 33 and 34 are changed by electromagnetic induction based on the change in the magnetic flux, and the transmission torque is detected based on the change in the coil output.

Further, according to the above configuration, when the torque is transmitted, the shafts 3 and 4 rotate relatively in one direction and the moving member 12
Moves in one direction, the first opening 4 according to the amount of movement.
The overlapping area between the third opening 41 and the outer periphery of the magnetic flux passage portion connected to one edge 41 ′ of the first concave portion 41 increases, and the overlap between the second opening 44 and the outer periphery of the magnetic flux passage portion continuous to one edge 42 ′ of the second concave portion 42. The area is reduced. When the shafts 3 and 4 rotate relative to each other in the other direction during the torque transmission and the moving member 12 moves in the other direction, the overlapping area between the first opening 43 and the outer periphery of the magnetic flux passing portion decreases according to the amount of movement, The overlapping area between the second opening 44 and the outer periphery of the magnetic flux passage increases. The magnetic flux passing through the magnetic flux passage changes according to the change of each overlapping area. When the shafts 3 and 4 rotate relative to each other, the first
The absolute value of the change in the overlapping area between the opening 43 and the outer periphery of the magnetic flux passage portion is equal to the absolute value of the change in the overlap area between the second opening 44 and the outer periphery of the magnetic flux passage portion. Therefore, the change of the magnetic flux passing through the magnetic flux passing portion according to the change of the overlapping area between the first opening 43 and the outer periphery of the magnetic flux passing portion and the change of the overlapping area of the second opening 44 and the outer periphery of the magnetic flux passing portion correspond to the change. The torque transmitted by the shafts 3 and 4 is detected based on the difference between the change in the magnetic flux passing through the magnetic flux passing portion and the torque detection sensitivity can be increased. Moreover, 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 this, the fluctuation of the detected torque due to the temperature fluctuation can be offset.

In this embodiment, each coil 33, 34
It is connected to a printed board 35 attached to the housing 2 via wiring. The torque detection circuit shown in FIG. 4 is formed on the printed board 35. In the circuit, the first coil 33 is connected to an oscillator 46 via a resistor 45, and the second coil 34 is connected to an oscillator 46 via a resistor 47.
, And the coils 33 and 34 are connected to a differential amplifier circuit 48. As a result, the torsion bar 8 is twisted by the torque transmission between the shafts 3 and 4, whereby the shafts 3 and 4 are relatively elastically rotated. The output area of the first and second coils 33 and 34 changes as the overlapping area with the outer periphery changes and the magnetic flux passing through the magnetic flux passing portion changes due to the change in the overlapping area. 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 the first opening 43 and the change in the magnetic flux passing through the magnetic flux passing portion overlapping the second opening 44, the two shafts 3 are used. , 4 are detected. A steering assist force is applied by an actuator (not shown) such as a motor driven according to 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.

According to the above configuration, the torque sensor 1 for detecting a torque in accordance with the movement of the moving member 12 in the axial direction of the shaft.
In the above, torque can be detected based on a change in coil output due to electromagnetic induction without using a differential transformer, and weight can be reduced. Further, the openings 43 and 44 and the concave portions 41 and 42 are easily formed, and the relative rotation amount is obtained when the shafts 3 and 4 are relatively rotated in one direction and when the shafts are relatively rotated in the other direction. Can be detected. A plurality of openings 43 and 44 are formed so as to be arranged side by side at intervals in the shaft circumferential direction.
Since the reference numerals 1 and 42 are provided over the entire area in the circumferential direction of the shaft, the change in the overlapping area between the outer periphery of the magnetic flux passage portion and the openings 43 and 44 according to the torque change is made as large as possible.
The torque detection sensitivity can be improved.

The present invention is not limited to the above embodiment. For example, instead of the first shaft 3, the outer periphery of the second shaft 4 or the outer periphery of both shafts 3, 4 may constitute a magnetic flux passage portion. In the shaft axial movement range of the moving member 12 corresponding to the torque detection range, the other edge 41 ″ of the first concave portion 41 overlaps the first opening 43 in the shaft radial direction, and the other edge 42 of the second concave portion 42 "Overlaps the second opening 44 in the radial direction of the shaft, and one edge 41 ′ of the first recess 41 and the second recess 4
2 may be arranged such that one edge 42 ′ does not overlap with the openings 43 and 44 in the shaft radial direction. Alternatively, one end of the first shaft 3 may be connected to a steering gear, and the other end of the second shaft 4 may be connected to a steering wheel. Further, the concave portion is not limited to the circumferential groove shape, for example, may have a shape along a quadrilateral having a pair of edges parallel to the shaft axis direction and a pair of edges parallel to the shaft circumferential direction, A plurality of the recesses may be provided at intervals in the shaft circumferential direction. Further, the torque sensor of the present invention may be used for detecting torque in a device other than the steering device.

[0031]

According to the present invention, it is possible to provide a torque sensor which can be reduced in weight and has excellent detection accuracy and detection sensitivity.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a main part of the torque sensor according to the embodiment of the present invention.

FIG. 3 is a partial development view of a moving member of the torque sensor according to the embodiment of the present invention.

FIG. 4 is a diagram showing a torque detection circuit according to the embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torque sensor 3 1st shaft 4 2nd shaft 12 Moving member 31, 32 Coil holder 33 1st coil 34 2nd coil 41 1st recess 42 2nd recess 43 1st opening 44 2nd opening

Claims (4)

[Claims] 1. A first shaft, a second shaft coaxially and elastically connected to the first shaft so as to be relatively rotatable, a cylindrical moving member coaxial with both shafts, and a relative rotation between the two shafts. A mechanism for interlocking both shafts and the moving member, so that the moving member moves in the shaft axis direction with respect to both shafts in accordance with the above, and is arranged so as to surround the moving member, so that an alternating magnetic field is generated. A coil that generates a magnetic flux, and a magnetic flux passage portion made of a magnetic material disposed at a passage position of a generated magnetic flux of the coil is configured by an outer periphery of at least one of the two shafts.
It has a magnetic flux regulating portion made of a non-magnetic material having conductivity which is arranged at a position where the generated magnetic flux of the coil passes while surrounding the magnetic flux passing portion, and a concave portion is formed in the magnetic flux passing portion, and the magnetic flux regulating portion has An opening is formed, and in the shaft radial direction,
The concave portion and the opening are arranged relative to each other so that the overlapping area between the outer periphery of the magnetic flux passage portion connected to the edge of the concave portion and the opening changes according to the movement of the moving member due to the relative rotation of the two shafts, and the overlapping area thereof A torque sensor for detecting a torque transmitted by both shafts based on a change in a magnetic flux passing through the magnetic flux passing portion in accordance with a change in the magnetic flux. The moving member moves axially in one direction according to the amount of relative rotation when both shafts rotate relative to one direction, and when both shafts rotate relative to each other in another direction.
The opening moves along a quadrilateral having a pair of edges parallel to the shaft axial direction and a pair of edges parallel to the shaft circumferential direction, wherein the opening moves in the axial direction in the other direction according to the relative rotation amount. It has a shape, and its concave portion is formed in a peripheral groove shape, and in the moving range of the moving member corresponding to the torque detection range,
One edge along the shaft circumferential direction in the concave portion is arranged so as to overlap with the opening in the shaft radial direction, and the other edge in the concave portion is arranged so as not to overlap with the opening in the shaft radial direction. The torque sensor according to claim 1. 3. A coil comprising a first coil and a second coil of the same specification arranged in parallel along a shaft axis direction as said coil, and said opening having a first opening arranged at an interval in the shaft axis direction. A second opening, and as the concave portion, a first concave portion and a second concave portion which are arranged at an interval in a shaft axis direction, and the first coil of the first concave portion has a first coil.
The second coil is disposed at a position where a magnetic flux passing through the opening is generated, and the second coil is disposed at a position where a magnetic flux passing through the second opening is generated. When the moving members move in one direction due to the relative rotation of both shafts in one direction, the overlapping area with each other increases, and the moving members move in the other direction by the relative rotation of both shafts in the other direction. At this time, the moving member is arranged relative to each other so that the overlapping area is reduced, and the second opening and the outer periphery of the magnetic flux passing portion connected to the edge of the second concave portion are moved by the relative rotation of the two shafts in one direction. When the moving members move in the other direction due to the relative rotation of the two shafts in the other direction, the overlapping areas with each other increase when the moving member moves in the other direction. , Relative rotation of both shafts At the time, the absolute value of the change in the overlap area between the first opening and the outer periphery of the magnetic flux passage portion connected to the edge of the first recess, and the absolute value of the change of the overlap area between the second opening and the outer periphery of the magnetic flux passage portion connected to the edge of the second recess. The absolute value of the change in the overlapping area is made equal to each other, and the change in the passing magnetic flux of the magnetic flux passing portion connected to the edge of the first recess in accordance with the change in the overlapping area and the change in the second recess in accordance with the change in the overlapping area. 3. The torque sensor according to claim 1, wherein the torque transmitted by the two shafts is detected based on a difference from a change in a passing magnetic flux of a magnetic flux passing portion connected to the edge. 4. A plurality of said first openings are formed in parallel at intervals in a shaft circumferential direction, and a plurality of said second openings are formed in parallel at intervals in a shaft circumferential direction. 4. The torque sensor according to claim 3, wherein the first recess is provided over the entire area in the shaft circumferential direction, and the second recess is provided over the entire area in the shaft circumferential direction. 5.