KR100408927B1 - A torque sensor - Google Patents

Abstract

The present invention discloses a torque sensor that can reduce the stress of the detection ring to improve the magnetic characteristics of the detection ring, the drive shaft and driven shaft connected on the same axis via a torsion bar, and the outer periphery of the drive shaft and driven shaft A torque sensor having a first, second, and third detection ring provided at an inner side of a sleeve and a sleeve press-fitted between a drive shaft and a second detection ring, wherein a stepped portion is provided on an outer circumferential surface of a sleeve in contact with an inner circumference of the second detection ring and a press-fitting surface It is characterized by being formed.

According to the present invention, it is possible to improve the magnetic properties of the detection ring by reducing the stress of the detection ring press-fitted by the sleeve, and also to prevent the magnetic signal detected in the detection ring from forming a magnetic path in the axial direction. Magnetic properties can be improved.

Description

Torque sensor {A TORQUE SENSOR}

The present invention relates to a torque sensor that detects a steering torque generated from a rotating shaft of a steering wheel of a vehicle in a non-contact manner, and more particularly, to a torque sensor that can improve the magnetic properties of the detection ring by reducing the stress of the detection ring. It is about.

The electric steering apparatus assisting the vehicle steering apparatus uses the rotational force of the motor. The rotational force of the motor is transmitted to the steering shaft or to the steering shaft or rack shaft by a transmission shaft comprising a gear or a belt. The shaft of the steering wheel is connected to the tie rod of the wheel to be steered through the pinion mechanism. A shaft is connected to the shaft to reinforce the steering force of the steering wheel, and the control unit for controlling the electric steering apparatus calculates an auxiliary steering instruction value according to the steering torque detected by the torque sensor and the vehicle speed detected by the vehicle speed sensor. . The controller controls the current supplied to the motor according to the calculated auxiliary steering instruction value.

1 is a cross-sectional view of a part of a conventional torque sensor, and includes three detection rings 5 at ends of a drive shaft 2 and a driven shaft 3 which are coaxially connected by a torsion bar 4 interposed therein. (6) (7) are provided with predetermined intervals in the axial direction, and the teeth 5a, 6a and 7a are provided on the surfaces of the three detection rings 5, 6 and 7 which face each other. Is formed.

The magnetic housing is formed inside the sensor housing 11 in a state of enclosing the teeth 5a, 6a and 7a of the three detecting rings 5, 6 and 7 facing each other. A temperature compensation detection coil assembly (not shown) and a magnetoresistance detection coil assembly (not shown) are respectively installed.

The three detection rings 5, 6, and 7 are made of a magnetic material, and the second detection ring 6 is installed on the drive shaft 2 with the sleeve 8 interposed therebetween, and the first detection ring. (5) and the third detection ring 7 are provided on the driven shaft 3.

In the conventional torque sensor configured as described above, when the motor is relatively rotated according to the torque generated by the drive shaft 2, the torsion bar 4 is twisted, and the first and third detection rings provided at the end of the driven shaft 3 are rotated. The overlapping amount changes according to the relative rotation between the tooth | gear part 7a of (5, 7) and the tooth | gear part 6a of the 2nd detection ring 6 provided in the edge part of the drive shaft 2 corresponding to it. Since the inductance value of the magnetoresistive detection coil assembly 13 changes when the amount of overlap is relatively changed, the torque generated in the shaft detects the torque acting on the torsion bar 4 by measuring the impedance of the coil.

However, the conventional torque sensor configured as described above stresses the detection ring 6 of the magnetic material according to the degree to which the sleeve 8 is press-fitted between the drive shaft 2 and the second detection ring 6 in a press fit manner. This stress has a disadvantage of lowering the magnetic properties of the detection ring (6).

In addition, the conventional torque sensor has a disadvantage in that the magnetic signal detected by the detection ring is transferred in the axial direction, the magnetic properties are lowered.

An object of the present invention is to provide a torque sensor capable of improving the magnetic properties of a detection ring by reducing the stress of the detection ring press-fitted by the sleeve.

Another object of the present invention is to provide a torque sensor capable of improving magnetic properties of the detection ring by blocking magnetic signals detected in the detection ring from forming a magnetic path in the axial direction.

In order to achieve the object as described above, the present invention is the first and second drive shafts and driven shafts connected on the same axis through the torsion bar to measure the torque of the steering wheel, the first and second provided on the outer periphery of the drive shaft and driven shaft 3, a torque sensor having a detection ring and a sleeve press-fitted between the drive shaft and the second detection ring, wherein a stepped portion is formed on an outer circumferential surface of the sleeve in contact with the inner circumference of the second detection ring and pressed against It provides torque sensor that can minimize stress.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

1 is a partial cross-sectional view showing a detection ring assembly structure of a conventional torque sensor.

Figure 2 is a partial cross-sectional view showing a sleeve assembly structure of the torque sensor according to the present invention.

3 is a graph showing a magnetic characteristic change curve of a detection ring to which a sleeve having a stepped portion according to the present invention is applied;

<Description of Symbols for Main Parts of Drawings>

22: drive shaft 23: driven shaft

24: torsion bar 25, 26, 27: detection ring

25a, 26a, 27a: tooth part 28: sleeve

30; Step

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a partial cutaway cross-sectional view showing the sleeve coupling structure of the torque sensor according to the present invention.

As shown in FIG. 2, the torque sensor according to the present invention includes three detection rings 25 at ends of the driving shaft 22 and the driven shaft 23 which are coaxially connected by the torsion bar 24 interposed therein. 26 and 27 are provided at predetermined intervals in the axial direction, and teeth 25a, 26a and 27a are formed on the surfaces of the three detection rings 25, 26 and 27 which face each other. do.

The second detection ring 26 is installed on the drive shaft 22 with the sleeve 28 interposed therebetween, and the third detection ring 27 is installed on the driven shaft 23. The detection rings 25, 26 and 27 are made of magnetic material, and the sleeve 28 is made of nonmagnetic material.

In addition, the stepped portion 30 is formed on the outer circumferential surface of the sleeve 28 according to the feature of the present invention. The stepped portion 30 is formed in an annular band on the outer circumference of the sleeve 28. When the sleeve 28 is press-fitted between the drive shaft 22 and the second detection ring 26, the outer circumferential surface of the sleeve 28 and the inner circumferential surface of the second detection ring 26 come into contact with the press-in surface, where the stepped portion 30 ) Reduces the area in contact with the indentation surface to minimize the occurrence of stress by the indentation of the second detection ring (26). That is, parts of the sleeve 28 and the second detection ring 26 except for the stepped portion 30 may be kept spaced apart by a predetermined interval G.

On the other hand, according to another embodiment of the present invention, an example of a semi-magnetic material having a magnetic shielding effect of the material of the sleeve 28 to block the magnetic signal detected in the first detection ring 26 in the axial direction For example, the magnetic property of the detection ring can be improved by using aluminum (Al).

3 is a graph illustrating a magnetic characteristic change curve of a detection ring to which a sleeve having a stepped portion according to the present invention is applied.

From the graph, it can be seen that the magnetic characteristic change curve of the detection ring to which the step is formed is improved by comparing with the detection ring to which the sleeve is not formed.

In the above description, it should be understood that those skilled in the art can only make modifications and changes to the present invention without changing the gist of the present invention as it merely illustrates a preferred embodiment of the present invention.

As described above, according to the present invention, it is possible to improve the magnetic characteristics of the detection ring by reducing the stress of the detection ring press-fitted by the sleeve, and also to form a magnetic path in the axial direction by the magnetic signal detected in the detection ring. By blocking the magnetic properties of the detection ring can be improved.

Claims (3)

Drive shafts and driven shafts connected on the same axis via the torsion bar for measuring torque of the steering wheel, first, second and third detection rings provided on the outer periphery of the drive shafts and driven shafts, drive shafts and second detection rings A torque sensor having a sleeve press-fitted in between And a stepped portion is formed on an outer circumferential surface of the sleeve in contact with the inner circumference of the second detection ring and the press-contacting surface. The torque sensor as claimed in claim 1, wherein the sleeve is made of a diamagnetic material. The torque sensor as claimed in claim 2, wherein the sleeve is made of aluminum (Al).