JP2003050168A - Torque sensor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a torque sensor, which can improve the torque detection accuracy and simplifying the manufacturing steps, and which reduces the number of parts. SOLUTION: The method for manufacturing the torque sensor comprises a step of integrating a first detection cylinder 13, made of a magnetic material with a sleeve 12 made of a nonmagnetic material to be engaged with a first shaft 3; a step of integrating a second shaft 4 elastically oppositely rotatable to the shaft 3 with a second detecting cylinder 14 made of a magnetic material opposed via a gap to one end of the cylinder 13. Transmission torque by both the shafts 3 and 4 is detected, based on the magnetic reluctance change to a passing magnetic flux of the opposed ends of the first and second cylinders 13 and 14. The method also comprises the steps of coupling the first shaft 3 to the second shaft 4, integrating the shaft 4 with the second cylinder 14, integrating the first cylinder 13 with the sleeve 12, then axially relatively moving the sleeve 12 to the shaft 3, thereby regulating the size of the gap therebetween. Thereafter, the shaft 3 is integrated with the sleeve 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor used for detecting a steering torque in a power steering device that applies a steering assist force according to a steering torque, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 7 shows a torque sensor 101 for detecting a steering torque in a conventional power steering system.
The torque sensor 101 includes a first shaft 103 supported by a housing 102 and a first shaft 103.
And a second shaft 104 that is elastically connected to the second shaft 104 via a torsion bar 115. The first
The shaft 103 is relatively rotatably supported via a bush 113 inserted in the center hole of the second shaft 104. The torsion bar 115 is connected to the shafts 103 and 104 via pins 118 and 119. A first detection cylinder 106 made of a magnetic material is rotatably fitted to the outer circumference of a sleeve 105 made of a non-magnetic material, which is rotatably fitted to the outer circumference of the first shaft 103.
A second detection cylinder 107 made of a magnetic material is press-fitted onto the outer periphery of the second shaft 104 so that the second detection cylinder 107 is rotatably fitted together. A third detection cylinder 108 made of a magnetic material is press-fitted onto the outer periphery of the first shaft 103 so that the third detection cylinder 108 is rotatably fitted together. One end of the first detection cylinder 106 and the second detection cylinder 10
One end of 7 is opposed to the other end with a gap therebetween. The other end of the first detection cylinder 106 and one end of the third detection cylinder 108 face each other with a gap therebetween. One end of the first detection cylinder 106,
One end of the second detection cylinder 107 and one end of the third detection cylinder 108 have a plurality of teeth 106a, 10 arranged in parallel along the circumferential direction.
7a and 108a. The other end of the first detection cylinder 106 is a flat surface. A first coil 110 that forms a first magnetic circuit by generating a magnetic flux that passes through one end of the first detection cylinder 106 and one end of the second detection cylinder 107;
The housing 102 holds a second coil 111 that forms a second magnetic circuit by generating a magnetic flux that passes through the other end of the first detection cylinder 106 and one end of the third detection cylinder 108. The magnetic resistance to the passing magnetic flux in the first magnetic circuit changes according to the elastic relative rotation amount according to the transmission torque of both shafts 103 and 104. Since the first detection cylinder 106 and the third detection cylinder 108 rotate together,
The magnetic resistance to the passing magnetic flux in the second magnetic circuit does not change depending on the change in the transmission torque of the shafts 103 and 104. Thereby, the torque transmitted by both shafts 103 and 104 can be detected based on the change in the magnetic resistance in the first magnetic circuit. Further, based on the deviation between the change in the magnetic resistance in the first magnetic circuit and the change in the magnetic resistance in the second magnetic circuit, the change in the detected torque due to the temperature change can be compensated.

In the prior art, the first shaft 103 described above is used.
A through hole 120 penetrating the sleeve 105 and the first detection cylinder 106 is formed by a drill, and a pin 121 is press-fitted into the through hole 120, whereby the first shaft 103, the sleeve 105, and the first detection cylinder 106 are formed. Are integrated.

When manufacturing the above-mentioned conventional torque sensor 101, one end of the first detection cylinder 106 and the second detection cylinder 10 are manufactured.
Since the gap between one end of 7 affects the magnetic resistance,
It is necessary to properly set the size of the gap to a value that enables highly accurate torque detection. Therefore, the first detection cylinder 1
06 to the second shaft 104 integrated with the second detection cylinder 107.
After being inserted via 13, the second shaft 104 is moved relative to the first shaft 103 in the axial direction, and the size of the gap is adjusted while monitoring the outputs of the coils 110 and 111. Then, the first shaft 103 and the second shaft 103 are connected via the torsion bar 115 and the pins 118 and 119.
It was connected to the shaft 104.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The size of the gap between the first detection cylinder 106 and the second detection cylinder 107 is determined by the size of both shafts 10.
When the adjustment is performed by the relative movement of the shafts 3 and 104 in the axial direction, the change in the size of the gap does not match the change in the relative movement distance of the shafts 103 and 104 in the axial direction. This is due to the inclinations of the shafts 103 and 104 with respect to the axial center of the shafts and errors such as straightness. Therefore, there is a problem that the torque detection accuracy is reduced.

The first detection cylinder 106 is a magnetic material,
The material is different from that of the sleeve 105 which is a non-magnetic material. Therefore, when the through hole 120 is formed, the amount of elastic deformation such that the first detection cylinder 106 and the sleeve 105 are pushed apart by the drill is different. Therefore, the inner diameter of the through hole 120 after the drill is pulled out is determined by the first detection tube 106.
Since it is different in the part in and the part in the sleeve 105, it is difficult to control the press-fitting load of the pin 121 into the through hole 120 to an appropriate value, and finishing processing by a reamer is required. Moreover, the through hole 12 by the drill
After the formation of 0, deburring and cleaning operations were required. As a result, there is a problem in that the number of parts by the pin 121 is increased, a hole is formed by a drill, a deburring and cleaning process and a finishing process by a reamer are required, which complicates the manufacturing process and increases cost. In addition, since the pin 121 positions the first detection cylinder 106 with respect to the first shaft 103, between the other end of the first detection cylinder 106 and one end of the third detection cylinder 108 depending on the positioning accuracy. The gap in the axial direction of the shaft changes. If the gap changes, the magnetic resistance of the second magnetic circuit changes, which may reduce the torque detection accuracy.

The third detection cylinder 108 is the first shaft 1
Since it is fitted by directly press-fitting into 03,
In order to allow the detection cylinder 108 and the first detection cylinder 106 to face each other, the portion of the first shaft 103 where the third detection cylinder 108 is fitted has a larger diameter than the portion where the first detection cylinder 106 is fitted. I needed to. Therefore, the first shaft 103 has a large diameter and a complicated shape, resulting in high material cost and processing cost.

It is an object of the present invention to provide a torque sensor which can solve the above problems.

[0009]

A torque sensor to which the present invention is applied includes a first shaft, a second shaft elastically rotatably coupled to the first shaft, and an outer circumference of the first shaft. A sleeve made of a non-magnetic material, a first detection cylinder made of a magnetic material integrated with the sleeve, a second shaft of the detection cylinder, and one end of the first detection cylinder having one end. A magnetic circuit is formed by generating a magnetic flux that passes through a second detection cylinder made of a magnetic material and arranged to face each other with a gap, and one end of the first detection cylinder and one end of the second detection cylinder. The magnetic resistance of the magnetic circuit to the passing magnetic flux in the magnetic circuit is changed according to the elastic relative rotation amount of the both shafts, and the torque transmitted by the both shafts is detected based on the change of the magnetic resistance. .

A method of manufacturing a torque sensor according to the present invention comprises:
The first shaft and the second shaft are elastically connected so as to be relatively rotatable, and the second shaft is provided with the second shaft.
The detection cylinder is integrated, and the first detection cylinder is integrated with the sleeve, and thereafter, the first relative movement of the sleeve fitted to the first shaft causes the first detection cylinder to move.
The size of the gap between one end of the detection cylinder and one end of the second detection cylinder is adjusted, and then the sleeve is integrated with the first shaft. According to the method of the present invention, after connecting the first shaft and the second shaft, the sleeve in which the first detection cylinder is integrated is moved in the axial direction relative to the first shaft. It is possible to adjust the size of the gap between one end of the second detection cylinder and one end of the second detection cylinder. Therefore, as compared with the case where adjustment is performed by the relative movement of the first shaft and the second shaft in the axial direction, the size of the gap can be adjusted without being affected by the inclination of the both shafts with respect to the mutual axial center and the error such as straightness. Can be adjusted. Moreover, since the sleeve is moved in the axial direction at a position close to the gap, the influence of the inclination of the sleeve and the first shaft with respect to each other's axial center, and the error such as straightness are small. This makes it possible to adjust the size of the gap with high accuracy and improve the torque detection accuracy.

In the torque sensor of the present invention, the sleeve is fitted to the first shaft so as to be relatively movable in the axial direction and then plastically deformed, whereby the sleeve is provided with a caulking portion, and the caulking portion is provided in the first shaft. The sleeve is integrated with the first shaft by being pressed against. According to the torque sensor of the present invention, the method of the present invention can be carried out. Moreover, since the sleeve made of a non-magnetic material is integrated with the first shaft by pressing the caulking portion against the first shaft, it is possible to integrate the first shaft and the sleeve without using a conventional pin. You can

The sleeve has a projecting portion that projects outward in the axial direction of the shaft, and a recess is provided on the outer periphery of the first shaft. The caulking portion pushes a part of the projecting portion into the recess. It is preferably formed by plastic deformation. As a result, the caulked portion can be easily plastically deformed, and the sleeve and the first shaft can be reliably integrated.

A third detection cylinder made of a magnetic material, which rotates together with the first detection cylinder and is arranged so that one end thereof opposes the other end of the first detection cylinder with a gap, and the first detection cylinder. A second coil that forms a second magnetic circuit by generating a magnetic flux that passes through the other end of the cylinder and one end of the third detection cylinder, a change in magnetic resistance with respect to the passing magnetic flux in the magnetic circuit, and a passage in the second magnetic circuit. A detection circuit for compensating a variation of the detected torque due to a temperature variation based on a deviation from a change in magnetic resistance with respect to the magnetic flux, the first detection cylinder and the third detection cylinder being fitted to the outer circumference of the sleeve, and An annular spacer made of a non-magnetic material sandwiched between the other end of the detection cylinder and one end of the third detection cylinder is fitted on the outer circumference of the sleeve, and the first detection cylinder, the annular spacer, and the third detection cylinder are connected to the shaft axis. When sandwiched from the direction A pair of sandwiching portions are provided which are integrated in the sleeve, the first detecting cylinder and the third
It is preferable that the detection cylinder is integrated with the sleeve by being sandwiched by the sandwiching portion together with the annular spacer. According to this configuration, the first detection cylinder and the third detection cylinder
The detection cylinder is integrated with the sleeve by being sandwiched by the sandwiching portion that is integrated with the outer circumference of the sleeve.
Accordingly, the first shaft, the sleeve, the first detection cylinder, and the third detection cylinder can be integrated without using a pin as in the related art. Further, since the first detection cylinder and the third detection cylinder are sandwiched together with the annular spacer, the gap in the shaft axial direction between the other end of the first detection cylinder and one end of the third detection cylinder is made constant. Can hold

One of the pair of sandwiching portions is constituted by a stepped portion provided on the sleeve so as to come into contact with one of the one end side of the first detection cylinder and the other end side of the third detection cylinder. The other of the pair of sandwiching portions has one end of the first detection cylinder and the other end of the third detection cylinder after the first detection cylinder, the annular spacer, and the third detection cylinder are fitted to the sleeve. The sleeve is formed by plastically deforming the sleeve so as to be in contact with the other one of the sides, and the force that plastically deforms the sleeve to form the other of the pair of sandwiching portions causes the first detection tube, the annular shape. Spacer, third
It is preferable that the detection cylinder is pressed against a stepped portion that constitutes one of the sandwiched portions. As a result, the first detection cylinder, the annular spacer,
The third detection cylinder can be pressed against the step portion, and the first detection cylinder and the third detection cylinder can be integrated with the first shaft.

The other of the sandwiched portions is formed by plastically deforming a projecting portion projecting outward from the end of the sleeve in the axial direction of the shaft so as to bend outward in the radial direction of the shaft. Is preferred. This allows
The first detection cylinder, the annular spacer, the third
The detection cylinder can be easily sandwiched.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In an electric power steering apparatus A shown in FIG. 1, a steering torque generated by steering of a steering wheel H is changed in steering angle from a steering shaft S to a wheel via a universal joint (not shown) and a steering gear. Communicate as you would. The type of the steering gear is not limited as long as the steering torque can be transmitted from the steering shaft S to the wheels so that the steering angle changes.
For example, a rack and pinion type steering gear that transmits the movement of the rack that meshes with the pinion that rotates by the steering torque to the wheels via a tie rod, a knuckle arm, or the like can be adopted.

A torque sensor 1 for detecting the steering torque transmitted by the steering shaft S is provided. The torque sensor 1 includes a sensor housing 2 and
An input shaft (first shaft) 3 and an output shaft (second shaft) 4 connected to the input shaft 3 are provided. The input shaft 3 and the output shaft 4 form the steering shaft S. That is, the steering shaft S is configured by connecting the upper shaft 31, the input shaft 3 and the output shaft 4. The steering wheel H is connected to one end of the upper shaft 31. The input shaft 3 is connected to the other end of the upper shaft 31 by being press-fitted through serration. A universal joint is connected to the other end of the output shaft 4. The upper shaft 31 is rotatably supported by a tubular steering column 32 via a bearing 33. One end of the sensor housing 2 is press-fitted into the steering column 32. A motor (electric actuator) M for generating a steering assist force is attached to the sensor housing 2.

As shown in FIG. 2, its output shaft 4
Is rotatably supported by the sensor housing 2 via a bearing 6a, and is rotatably supported by a cover 9 attached to the sensor housing 2 via a bearing 6b. Its input shaft 3 and output shaft 4
Has a cylindrical shape by providing the central holes 3a and 4a. The input shaft 3 is inserted into the center hole 4a of the output shaft 4.
One end side of is inserted such that relative rotation is possible. It is preferable that a supporting member such as a bush is interposed between the output shaft 4 and the input shaft 3 to regulate the relative whirling of the input shaft 3 and the output shaft 4 about their axes.

A torsion bar 8 is inserted as an elastic member into the center holes 3a, 4a of the input shaft 3 and the output shaft 4, respectively. The torsion bar 8 has one end connected to the input shaft 3 by being press-fitted through the serration and the other end connected to the output shaft 4 by a pin 24. As a result, the output shaft 4 is elastically rotatable relative to the input shaft 3 in the axial center in accordance with the steering torque.

The output shaft 4 has the bearing 6a.
And the worm wheel 10 are press-fitted. The worm 11 meshing with the worm wheel 10 is driven by the steering assist force generating motor M. As a result, the steering assist force generated by the motor M according to the detected steering torque is transmitted to the steering shaft S via the worm 11 and the worm wheel 10, and the steering assist force according to the detected steering torque is applied. It

A sleeve 12 made of a non-magnetic material is fitted around the outer periphery of the input shaft 3. The fitting of the sleeve 12 to the outer periphery of the input shaft 3 is performed by a light press-fitting such that rattling does not occur. Depending on the light press-fitting, the sleeve 12 moves relatively to the input shaft 3,
Relative rotation is not blocked.

As shown in FIGS. 3 and 4, the sleeve 1 is fitted on the input shaft 3 so as to be relatively movable in the axial direction.
A plurality of caulked portions 12 'are provided by plastically deforming 2. That is, the sleeve 12 has a ring-shaped protruding portion 1 that protrudes outward in the axial direction of the shaft from one end.
2a, and a plurality of recesses 3'are provided on the outer circumference of the input shaft 3 at intervals in the circumferential direction. In this embodiment, each recess 3 ′ opens at the outer circumference and one end of the input shaft 3. Each caulking portion 12 'is formed by plastically deforming a part of the protruding portion 12a into each recess 3'. By pressing each caulking portion 12a against the input shaft 3, the sleeve 12 is integrated with the input shaft 3, and the sleeve 12 and the input shaft 3 rotate together.
Move with you.

A first detecting cylinder 13 made of a magnetic material is fitted around the outer circumference of the sleeve 12. The sleeve 12
The fitting of the first detection cylinder 13 to the outer periphery of the first detection cylinder 13 is performed by light press-fitting such that rattling does not occur. Depending on the light press-fitting, relative movement of the first detection cylinder 13 with respect to the sleeve 12,
Relative rotation is not blocked. The second detection cylinder 14 made of a magnetic material is press-fitted onto the outer circumference of the output shaft 4, so that the second detection cylinder 14 is integrated with the output shaft 4, and the second detection cylinder 1
4 and the output shaft 4 rotate together and move together. A third detection cylinder 15 made of a magnetic material is fitted on the outer circumference of the sleeve 12. The fitting of the third detection cylinder 15 to the outer circumference of the sleeve 12 is performed by light press-fitting to such an extent that rattling does not occur. Depending on the light press-fitting, relative movement and relative rotation of the third detection cylinder 15 with respect to the sleeve 12 are performed. Is not blocked.

One end of the first detection cylinder 13 is connected to the second detection cylinder 1
4 are opposed to each other with a gap δa at one end. As shown in FIG. 3, the other end of the first detection cylinder 13 faces one end of the third detection cylinder 15 with a gap δ. One end of the first detection cylinder 13, one end of the second detection cylinder 14, and one end of the third detection cylinder 15 have a plurality of teeth 13a, 14 arranged in parallel along the circumferential direction.
a, 15a. The first detection cylinder 13
The other end of is a flat surface.

The other end of the first detection cylinder 13 and the third detection cylinder 1
An annular spacer 7 made of a non-magnetic material is fitted to the outer circumference of the sleeve 12 between one end of the sleeve 5. The fitting of the annular spacer 7 to the outer circumference of the sleeve 12 is performed by a light press-fitting to the extent that rattling does not occur.
The axial dimension of the annular spacer 7 is made equal to the gap δ between the other end of the first detection cylinder 13 and the one end of the third detection cylinder 15, whereby the annular spacer 7 is moved to the first detection cylinder 13.
It is sandwiched between the other end and the one end of the third detection cylinder 15.

On the outer circumference of the sleeve 12, a pair of sandwiching portions 21 and 22 are integrated. The sandwiching part 2
1 and 22, the first detection cylinder 13, the annular spacer 7 and the third
The detection cylinder 15 is sandwiched from the shaft axial direction. The first detection cylinder 13 and the third detection cylinder 15 have the sandwiching portion 2
It is integrated with the sleeve 12 by being sandwiched by the annular spacers 1 and 22 together with the annular spacer 7, and the first detection cylinder 13, the third detection cylinder 15 and the sleeve 12 rotate together and move together.

The one sandwiching portion 21 is composed of a stepped portion provided on the outer circumference of the sleeve 12 so as to contact the other end side of the third detecting cylinder 15.

The other sandwiching portion 22 is the sleeve 1 thereof.
2, the first detection cylinder 13, the annular spacer 7, and the third detection cylinder 15
After being fitted, the sleeve 12 is plastically deformed so as to come into contact with the one end side of the first detection cylinder 13. In the present embodiment, the other sandwiching portion 22 contacts between the teeth 13 a of the first detection cylinder 13.
That is, the other sandwiching portion 22 is configured by a thin ring-shaped projecting portion 22 ′ that projects outward from the one end of the sleeve 12 in the axial direction of the shaft before the plastic deformation thereof. Each tooth 13a at each protruding portion 22 '
By plastically deforming the portion between the portions from the state shown by the solid line in FIG. 3 to the state shown by the broken line so as to bend outward in the radial direction of the shaft, (1) in FIG.
As shown in (2), the other sandwiching portion 22 is formed. By the force that plastically deforms the protruding portion 22 ′ to form the other sandwiched portion 22, the first detection cylinder 13,
The annular spacer 7 and the third detection cylinder 15 are pressed against the stepped portion forming the one sandwiching portion 22. It should be noted that one sandwiching portion 21 constituted by the step is in contact with the teeth 13a on one end side of the first detection cylinder 13,
The other sandwiching portion 22 formed by plastically deforming each protruding portion 22 ′ may be in contact with the other end side of the third detection cylinder 15.

One end of the first detection cylinder 13 and the second detection cylinder 1
The first coil 16 forming the first magnetic circuit is generated by the magnetic flux passing through one end of the first coil 4 and is held by the housing 2. The magnetic flux generated by the first coil 16 passes through the first detection cylinder 13, the second detection cylinder 14, and the first holder 17. The housing 2 holds the second coil 18 forming the second magnetic circuit by generating a magnetic flux passing through the other end of the first detection cylinder 13 and one end of the third detection cylinder 15. The magnetic flux generated by the second coil 18 is generated by the first detection cylinder 1
3, the third detection cylinder 15, and the second holder 19 are passed.

A detection circuit is provided on a circuit board (not shown) attached to the housing 2. FIG. 6 shows an example of the detection circuit, in which the first coil 16 includes a resistor 42.
Is connected to the oscillator 43 via the resistor 44, and the second coil 18 is connected to the oscillator 43 via the resistor 44. The first coil 16 is connected to the inverting input terminal of the operational amplifier 45,
The coil 18 is connected to the non-inverting input terminal of the operational amplifier 45. When torque is transmitted by the shafts 3 and 4, the torsion bar 8 is twisted according to the torque, and the first detection cylinder 13 and the second detection cylinder 14 relatively rotate about the same axis. By this relative rotation, the tooth 1 at one end of the first detection cylinder 13
3a and the tooth 14a at one end of the second detection cylinder 14 change in the area of the overlapping portion in the axial direction.
The magnetic resistance to the passing magnetic flux in the magnetic circuit changes according to the elastic relative rotation amount of both shafts 3 and 4 due to the torque change. The output voltage of the first coil 16 changes according to the change. First detection cylinder 13 and third detection cylinder 15
Since they rotate together, the magnetic resistance to the passing magnetic flux in the second magnetic circuit does not fluctuate depending on the change in the transmission torque by the shafts 3 and 4. The magnetic resistance in the first magnetic circuit is made equal to the magnetic resistance in the second magnetic circuit when the torque is not transmitted by the shafts 3 and 4. That is, since the magnetic resistance in the second magnetic circuit does not fluctuate due to the change in the transmission torque due to the shafts 3 and 4, the output fluctuation of the first coil 16 and the output fluctuation of the second coil 18 due to the temperature fluctuation are operational amplifiers. Canceled at 45. Thereby, the torque transmission by the both shafts 3 and 4 is detected based on the change in the magnetic resistance in the first magnetic circuit, and based on the deviation between the change in the magnetic resistance in the first magnetic circuit and the change in the magnetic resistance in the second magnetic circuit. A detection circuit for compensating the fluctuation of the detected torque due to the temperature fluctuation is configured. The steering assist force generating motor M is driven according to the detected torque, and the steering assist force is applied.

When the torque sensor 1 is manufactured, the input shaft 3 and the output shaft 4 are connected via the torsion bar 8, the second detection cylinder 14 is integrated on the outer periphery of the output shaft 4, and First detection cylinder 13 and first
The detection cylinder 13 is integrated with the sleeve 12 as described above, and the sleeve 12 is fitted onto the input shaft 3 so as to be movable in the axial direction. Thereafter, the output of the coils 16 and 18 is monitored for the size of the gap δa between the one end of the first detection cylinder 13 and the one end of the second detection cylinder 14 by the relative movement of the sleeve 12 in the axial direction with respect to the input shaft 3. However, the sleeve 12 is integrated with the input shaft 3 by plastically deforming a part of the protruding portion 12a into each recess 3'to form the caulking portion 12 '.

According to the above-described embodiment, when manufacturing the torque sensor 1, after the input shaft 3 and the output shaft 4 are connected, the sleeve 12 in which the first detection cylinder 13 is integrated is attached to the input shaft 3. By making relative movement in the axial direction, the size of the gap δa between one end of the first detection cylinder 13 and one end of the second detection cylinder 14 can be adjusted. That is, the size of the gap δa can be adjusted without being affected by the inclination of the input shaft 3 and the output shaft 4 with respect to the mutual axial center and the influence of errors such as straightness. Moreover, since the sleeve 12 is moved in the axial direction at a position close to the gap δa, the influence of the inclination of the sleeve 12 and the input shaft 3 with respect to the mutual axial center and the influence of straightness and the like are small. This makes it possible to adjust the size of the gap with high accuracy and improve the torque detection accuracy.
Since the sleeve 12 is integrated with the input shaft 3 by pressing the caulking portion 12 ′ onto the input shaft 3, the input shaft 3 and the sleeve 12 can be integrated without using a pin as in the prior art. . Moreover, the caulking portion 12 'can be easily plastically deformed, and the sleeve 12 and the input shaft 3 can be reliably integrated. Further, since the first detection cylinder 13 and the third detection cylinder 15 are fitted to the outer circumference of the sleeve 12 and are integrated with the sleeve 12 by being sandwiched by the sandwiching portions 21 and 22, the first detection cylinder 13 and the third detection cylinder 15 are 3 Detection tube 1
5 can be integrated into the sleeve 12 without the use of conventional pins. Since the first detection cylinder 13 and the third detection cylinder 15 are sandwiched together with the annular spacer 7, the gap δ between the other end of the first detection cylinder 13 and one end of the third detection cylinder 15 is made constant. Can hold Further, by forming one of the sandwiching portions 22 by plastically deforming the protruding portion 22 ′ of the sleeve 12, the stepped portion that forms the other sandwiching portion 21 with the first detection cylinder 13, the annular spacer 7, and the third detection cylinder 15 is formed. The first detection cylinder 13 and the third detection cylinder 15 can be integrated with the input shaft 3 by pressing them against the section, and the insertion can be easily performed.

The present invention is not limited to the above embodiment. For example, the present invention can be applied to a torque sensor used in a device other than the electric power steering device. In the above embodiment, the input shaft 3 is the first shaft and the output shaft 4 is the second shaft, but the input shaft 3 may be the second shaft and the output shaft 4 may be the first shaft. Further, the integration of the sleeve with the first shaft and the integration of the sleeve with each detection cylinder are not limited to those using the caulked portion.

[0034]

According to the present invention, the torque detection accuracy can be improved, the number of parts can be reduced and the manufacturing process can be simplified, and the shaft which is a component can be formed into a small diameter with a simple shape to reduce the material cost and the processing cost. A torque sensor that can be reduced and a manufacturing method thereof can be provided.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional view of the torque sensor according to the embodiment of the present invention.

FIG. 3 is a partially cutaway sectional view of a main part of the torque sensor according to the embodiment of the present invention.

FIG. 4 is a front sectional view of a sleeve and an input shaft in the torque sensor according to the embodiment of the present invention.

5A is a view as seen from an arrow A in FIG. 3, and FIG. 5B is a view as seen from an arrow B.

FIG. 6 is an explanatory diagram of a circuit configuration in the torque sensor according to the embodiment of the present invention.

FIG. 7 is a sectional view of a conventional torque sensor.

[Explanation of symbols]

1 Torque sensor 2 housing 3 Input shaft (first shaft) 4 Output shaft (second shaft) 7 Annular spacer 12 sleeves 12a protruding part 12 'Caulking part 13 First detection tube 14 Second detection tube 15 Third detection tube 16 First coil 18 second coil 21, 22 sandwiching part

Claims (5)

[Claims] 1. A first shaft, a second shaft elastically rotatably coupled to the first shaft, a sleeve made of a non-magnetic material fitted on the outer periphery of the first shaft, and the sleeve. A first detection cylinder made of a magnetic material, and a second detection shaft made of a magnetic material that is integrated with the second shaft and has one end opposed to one end of the first detection cylinder with a gap. Of the second detection cylinder and a coil forming a magnetic circuit by generating a magnetic flux that passes through one end of the first detection cylinder and one end of the second detection cylinder, and the magnetic resistance to the passing magnetic flux in the magnetic circuit. Is changed according to the elastic relative rotation amount of both shafts, and when manufacturing the torque sensor that detects the torque transmitted by both shafts based on the change in the magnetic resistance, the first shaft and the first shaft Two And a shaft, which is elastically rotatably connected to each other, the second detection cylinder is integrated with the second shaft, and the first detection cylinder is integrated with the sleeve, and thereafter, the first shaft is integrated. The axial relative movement of the sleeve fitted in the sleeve adjusts the size of the gap between the one end of the first detection cylinder and the one end of the second detection cylinder, and then the sleeve is attached to the first shaft. A method for manufacturing a torque sensor, characterized by integrating the above. 2. A first shaft, a second shaft elastically rotatably coupled to the first shaft, a sleeve made of a non-magnetic material fitted on the outer periphery of the first shaft, and the sleeve. A first detection cylinder made of a magnetic material, and a second detection shaft made of a magnetic material that is integrated with the second shaft and has one end opposed to one end of the first detection cylinder with a gap. Of the second detection cylinder and a coil forming a magnetic circuit by generating a magnetic flux that passes through one end of the first detection cylinder and one end of the second detection cylinder, and the magnetic resistance to the passing magnetic flux in the magnetic circuit. In the torque sensor that detects the torque transmitted by the shafts based on the change in the magnetic resistance of the shafts. The sleeve is provided with a caulking portion by being fitted so as to be relatively movable and then plastically deformed, and the caulking portion is pressed against the first shaft, so that the sleeve is integrated with the first shaft. Characteristic torque sensor. 3. The sleeve has a projecting portion that projects outward in the axial direction of the shaft, and a recess is provided on the outer periphery of the first shaft, and the caulking portion pushes a part of the projecting portion into the recess. The torque sensor according to claim 2, wherein the torque sensor is formed by plastic deformation. 4. A third detection cylinder made of a magnetic material, which is arranged so as to rotate together with the first detection cylinder and has one end opposed to the other end of the first detection cylinder with a gap therebetween, and the third detection cylinder. A second coil that forms a second magnetic circuit by generating a magnetic flux that passes through the other end of the first detection cylinder and one end of the third detection cylinder, a change in magnetic resistance with respect to the passing magnetic flux in the magnetic circuit, and a second magnetic circuit. And a detection circuit for compensating for a variation due to temperature variation of the detected torque based on a deviation from a change in magnetic resistance with respect to the passing magnetic flux at, and the first detection cylinder and the third detection cylinder are fitted to the outer circumference of the sleeve, and An annular spacer made of a non-magnetic material, which is sandwiched between the other end of the first detection cylinder and one end of the third detection cylinder, is fitted to the outer circumference of the sleeve to connect the first detection cylinder, the annular spacer, and the third detection cylinder. When sandwiched from the shaft axial direction A pair of sandwiching portions are provided which are integrated in the sleeve, the first detecting cylinder and the third
The torque sensor according to any one of claims 1 to 3, wherein the detection cylinder is integrated with the sleeve by being sandwiched by the sandwiching portion together with the annular spacer. 5. A stepped portion provided on the sleeve so that one of the pair of sandwiching portions is in contact with one of the one end side of the first detection cylinder and the other end side of the third detection cylinder. The other of the pair of sandwiching portions is configured such that, after the first detection cylinder, the annular spacer, and the third detection cylinder are fitted to the sleeve, the other end of the first detection cylinder and the third detection cylinder are The first detection tube is formed by plastically deforming the sleeve so as to be in contact with the other of the other end sides, and by the force of plastically deforming the sleeve to form the other of the pair of sandwiching portions. , Annular spacer, third
The torque sensor according to claim 4, wherein the detection cylinder is pressed against a stepped portion that constitutes one of the sandwiched portions.