JP2002116097A - Torque detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in temperature compensation and effectively use a plurality of coils in a torque detecting device. SOLUTION: An input shaft and an output shaft are connected by a torsion bar 15 in such a way as to be relatively rotated. An outer core 21 is fixed to the inner circumferential surface of a housing 10 integrally rotated with the output shaft, and coils 22-25 are assembled to protruded parts 21b-21c. An inner core 33 is fixed onto the outer circumferential surface of a sleeve 32 integrally rotated with the input shaft. A projected part 33b is located at the middle of the protruded parts 21b and 21e, and a projected part 33c is located in the middle of the protruded parts 21c and 21d. As the inductances of the coils 22 and 24 and the inductances of the coils 23 and 25 are changed in the opposite directions according to changes in the relative locations of the outer core 21 and the inner core 33 according to torque acting on the input shaft and the output shaft, the torque is detected according to their differences.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for detecting a torque acting on a rotating shaft such as a steering shaft of a vehicle.

[0002]

2. Description of the Related Art Conventionally, this type of apparatus is disclosed in
As shown in Japanese Patent Application Publication No. 00-2603, an input shaft and an output shaft assembled in a cylindrical housing so as to be rotatable relative to each other are connected by a torsion bar, and arranged on the inner peripheral surface of the housing. First and second cylindrical members that rotate integrally with the input shaft and the output shaft, respectively, are interposed in the magnetic path of the first coil so as to face each other, and the first and second cylindrical members are provided along the circumferential direction along the circumferential direction. A plurality of openings are formed at predetermined intervals, and a torque acting on the input shaft and the output shaft is detected by a change in inductance of the first coil according to a relative position between the input shaft and the output shaft. Like that.

In this device, the magnetic path of the second coil is formed by disposing the second coil on the inner peripheral surface of the housing at a predetermined distance from the first coil in the axial direction. A temperature compensation of torque detected by a change in inductance of the first coil is formed in proximity to a magnetic path so that a change in inductance of the first coil due to temperature is canceled by a change in inductance of the second coil due to temperature. To do.

[0004]

In the above-mentioned conventional device, although the temperature of the detected torque is compensated, the second coil is specially provided for temperature compensation and is effective for detecting the torque. And the structure of the magnetic path is different from that of the first coil, so that accurate temperature compensation cannot be expected.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned problems, and an object of the present invention is to improve the accuracy of temperature compensation and to effectively use a plurality of coils in order to improve a torque detecting device. An object of the present invention is to provide a torque detecting device.

In order to achieve the above object, a structural feature of the present invention is that an annular shaft provided so as to rotate integrally with one of an input shaft and an output shaft which are connected to each other by a torsion bar so as to be relatively rotatable. An outer core, at least a first coil and a second coil which are respectively mounted on the inner peripheral surface of the outer core along the circumferential direction at predetermined intervals, and integrated with the other of the input shaft and the output shaft. An inner core that is provided radially inside the first and second coils so as to rotate and that has a protruding portion that protrudes radially outward at a position between the circumferential directions of the first and second coils. Detecting a torque acting on the input shaft and the output shaft based on a change in inductance of the first and second coils according to a relative position between the first and second coils and the protrusion of the inner core. Lies in that it has.

In this case, for example, the outer core is fixed to a first member that rotates integrally with one of the input shaft and the output shaft, and the inner core is connected to the other of the input shaft and the output shaft. It can rotate with the shaft and be fixed to a second member provided radially inward with respect to the outer core.

[0008] In the present invention configured as described above,
When a torque is applied to the input shaft and the output shaft to cause a relative displacement between the input shaft and the output shaft due to the torsion of the torsion bar, a relative position between the first and second coils and the inner core also changes. , The inner core approaches one of the first and second coils and moves away from the other coil. Accordingly, the inductance of the one coil increases, and conversely, the inductance of the other coil decreases. As described above, since the inductances of the first and second coils change in opposite directions according to an increase in the torque acting on the input shaft and the output shaft, the changes in these inductances are taken out by voltage change or the like. Then, the torque can be detected by effectively using the changes in both the inductances of the first and second coils. Then, even if iron powder adheres to a part of the outer core, the inner core, or the like, and it is difficult to take out the change in inductance of one of the first and second coils, the change in inductance of the other coil can be taken out. Although detection accuracy is deteriorated, torque detection is ensured, which is preferable in fail-safe.

Further, even if the inductances of the first and second coils are affected by the temperature, the changes in the inductances of the first and second coils due to the temperature change appear in the same direction. The effect of temperature can be canceled by a method or the like, and temperature compensation can be easily and reliably realized. In this case, the first and second coils use the inner core as a common magnetic path, and the respective magnetic paths are easily realized with the same configuration, so that the accuracy of the temperature compensation is improved.

Further, in the above invention, it is preferable that the outer core and the inner core are constituted by laminated steel sheets. According to this, the eddy current loss can be suppressed small, and the magnetic resistance of the magnetic path can be suppressed small. As a result, the excitation frequency of the first and second coils can be increased while suppressing the eddy current loss to a small value, and a large change in inductance due to the coils can be obtained. it can.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of the torque detecting device according to the embodiment, and FIG.
FIG. 4 is a plan sectional view of the torque detection device viewed along a line.

This torque detecting device includes a stepped cylindrical housing 10. The housing 10 supports an input shaft 12 coaxially rotatably via a ball bearing 11 on the inner peripheral surface of the large diameter portion 10a. The output shaft 13 is provided with a pin 1 on the small diameter portion 10b of the housing 10.
4 so as to be coaxially and integrally rotated. The input shaft 12 and the output shaft 13 are connected to a torsion bar 15.
For relative rotation. One end of the torsion bar 15 is connected to the input shaft 12 by a pin 16 so as to rotate integrally with the input shaft 12, and the other end of the torsion bar 15 integrally rotates with the output shaft 13 by a pin 17 at the other end. It is connected as follows. When this torque detecting device is applied to a steering device for a vehicle, the input shaft 12 corresponds to a rotating shaft on the steering wheel side of the vehicle, and the output shaft 13 corresponds to a rotating shaft on the wheel side.

An outer core 21 is mounted on the lower inner peripheral surface of the large diameter portion 10a of the housing 10. The outer core 21 is formed of a laminated steel sheet in which a plurality of thin plates formed of a magnetic material having a high magnetic permeability are stacked in the axial direction of the housing 10, and has an outer diameter substantially equal to the inner diameter of the large diameter portion 10a. An annular portion 21a fixed on the inner peripheral surface of the large-diameter portion 10a projects radially inward from the annular portion 21a at a predetermined interval along the circumferential direction (specifically, at 90-degree intervals). Four projections 21b, 21c, 21d,
21e. The projections 21b and 21d constitute a first group of projections, and the projections 21c and 21e constitute a second group of projections. Each projection 2 of the outer core 21
Coils 22 to 25 are assembled to 1b to 21e, respectively. The coils 22 and 24 constitute a first group of coils, and the coils 23 and 25 constitute a second group of coils.

A housing 1 is provided on the outer peripheral surface of the input shaft 12.
A sleeve 32 that rotates integrally with the input shaft 12 is fixed by a pin 31 in the large-diameter portion 10a of the zero. The outer core 21 and the coil 2
An inner core (rotor) 33 is attached at the same position in the axial direction as 2-25. This inner core 33
Also, the outer peripheral surface of the sleeve 32 is formed by laminating a plurality of thin plates made of a magnetic material having high magnetic permeability in the axial direction of the housing 10 and having an inner diameter substantially equal to the outer diameter of the sleeve 32. At a predetermined interval along the circumferential direction from the annular portion 33a fixed to the
It comprises two protrusions 33b and 33c protruding radially outward from the annular portion 33a (at intervals of degrees).

The projecting portions 33b of the outer core 21 are formed when the torsion bar 15 is not twisted (there is no relative displacement between the input shaft 12 and the output shaft 13). And the projecting portion 21 which is located at the center in the circumferential direction of the coils 22 and 25 and is separated by a small predetermined gap.
b, 21e. The projecting portion 33c is located at the center in the circumferential direction of the projecting portions 21c and 21d of the outer core 21 and the coils 23 and 24 in a state where the torsion bar 15 is not twisted, and is spaced apart from the projecting portion by a small predetermined gap. 21c and 21d.

Next, an example of a detection circuit for detecting the torque acting on the input shaft 12 and the output shaft 13 using the torque detecting device configured as described above will be described. In this detection circuit, as shown in the block diagram of FIG. 3, coils 22 and 24 belonging to a first group are connected in series, and coils 23 and 25 belonging to a second group are connected in series. One ends of the coils 22 and 24 are connected to an oscillator 41 via a resistor 42, and the other ends are grounded. One end of each of the coils 23 and 25 is connected to the oscillator 41 via the resistor 43, and the other end is grounded.

Voltage detectors 44 and 45 are connected to one ends of the coils 22 and 24 and one ends of the coils 23 and 25, respectively. The voltage detectors 44 and 45 each include a rectifier circuit, a smoothing circuit, and the like, and detect the amplitude value (voltage value VT1, VT2) of the AC signal at each end of the coils 22, 24 and the coils 23, 25, respectively. An arithmetic unit 46 is connected to these voltage detectors 44 and 45, and the arithmetic unit 46 outputs a difference voltage VT1-VT2 between the two voltage values VT1 and VT2 as a torque detection value.

Next, the operation of the embodiment configured as described above will be described. The coils 22, 2 are connected via the resistors 42, 43.
When the AC signal from the oscillator 41 is supplied to one end of each of the coils 5 and 5, the AC signal flows through each series circuit including the coils 22 and 24 and the coils 23 and 25. The magnetic flux generated by the alternating current signals flowing through the coils 22 and 24 includes a protrusion 21 b, a protrusion 33 b, and an annular portion 33.
a, the projection 33c, the projection 21d, and the annular portion 21a. The magnetic flux generated by the AC signals flowing through the coils 23 and 25 passes through a magnetic path including the protrusion 21c, the protrusion 33c, the annular portion 33a, the protrusion 33b, the protrusion 21e, and the ring 21a in FIG. Pass in the direction of the paper.

If no torque is acting on the input shaft 12 and the output shaft 13 (torque is “0”) and the torsion bar 15 is not twisted, the projection 33 b of the inner core 33 Projections 21b, 21e
Of the inner core 33, and the protrusion 33c of the inner core 33 is located at the center of the protrusions 21c and 21d of the outer core 21. In this state, the inductances of the coils 22 to 25 (more precisely, the inductances of the coils 22 to 25 related to the outer core 21, the inner core 33, etc.) are all equal, and the voltage values VT1, VT2 detected by the voltage detectors 44, 45 Are equal. Therefore, in this case, the arithmetic unit 46 calculates “0” as the difference voltage VT1−VT2, and outputs a torque detection signal representing the same “0”.

On the other hand, the input shaft 12 is turned to the right in FIG.
When a relative rotation difference is generated between the input shaft 12 and the output shaft 13, the protrusions 33 b, 3 of the inner core 33 increase as the rotation difference, that is, the torque acting on the input shaft 12 and the output shaft 13 increases.
3c is a projection 2 of the outer core 21 belonging to the first group.
1b and 21d and the coils 22 and 24, respectively, and away from the protrusions 21e and 21c of the outer core 21 and the coils 25 and 23 belonging to the second group. Thereby, the coils 22 belonging to the first group,
As each inductance of 24 increases,
Each inductance of the coils 23 and 25 belonging to the second group decreases. Therefore, as indicated by the solid line in the right half of FIG. 4, as the torque acting on the input shaft 12 and the output shaft 13 increases, the voltage value VT1 detected by the voltage detector 44 increases, and The voltage value VT2 detected by the detector 45 decreases. And the arithmetic unit 46
Calculates the difference voltage VT1-VT2 between the two voltage values VT1 and VT2, and outputs the calculated value as a detected torque. as a result,
A positive value is obtained for the rightward rotation of the input shaft 12 in FIG. 2, and a torque detection signal is obtained which increases as the torque acting on the input shaft 12 and the output shaft 13 increases.

Conversely, when the input shaft 12 is rotated leftward in FIG. 2 and the torsion bar 15 is twisted, a relative rotation difference between the input shaft 12 and the output shaft 13 is generated. As the rotational difference, that is, the torque acting on the input shaft 12 and the output shaft 13 increases, the protrusions 33b, 33c of the inner core 33 become more protruded from the protrusions 21e, 21c and the coils 25, 23 of the outer core 21 belonging to the second group. , And away from the projections 21 b and 21 d and the coils 22 and 24 of the outer core 21 belonging to the first group. As a result, the respective inductances of the coils 22 and 24 belonging to the first group decrease, and the coils 23 and 25 belonging to the second group decrease.
Each inductance increases. Therefore, as indicated by the solid line in the left half of FIG. 4, as the torque acting on the input shaft 12 and the output shaft 13 increases, the voltage value VT1 detected by the voltage detector 44 decreases, and The voltage value VT2 detected by the detector 45 increases. Then, the arithmetic unit 46 calculates the difference voltage V between the two voltage values VT1 and VT2.
Calculate T1-VT2 and output the calculated value as detected torque. As a result, a torque detection signal that represents a negative value with respect to the leftward rotation of the input shaft 12 in FIG. 2 and whose absolute value increases as the torque acting on the input shaft 12 and the output shaft 13 increases. can get.

As can be understood from the above description of operation, the first group of coils 22 and 24 and the second group of coils 23 and 25 change in opposite directions according to the torque acting on the input shaft 12 and the output shaft 13. Since the torque is detected using the change of each inductance of
Changes in both inductances of the coils 22 and 24 of the group and the coils 23 and 25 of the second group are effectively used, and the torque is accurately detected.

Further, iron powder adheres to a part of the outer core 21, the inner core 33, etc.
Even if it is difficult to take out the change in the inductance of the coil of either one of the coils 23 and 25 of the second group, the change in the inductance of the other group can be taken out, so that the detection accuracy deteriorates. However, torque detection is ensured, which is preferable for fail-safe.

Further, even if the environmental temperature of the torque detecting device having the above configuration changes and the inductance of each of the coils 22 to 25 changes, the change in the inductance of the coils 22 and 24 of the first group and the change of the inductance of the coils of the second group. Changes in inductances 23 and 25 show the same change tendency due to temperature change. Thereby, as indicated by the broken line in FIG. 4, the voltage value VT1 'detected by the voltage detector 44 and the voltage value VT2' detected by the voltage detector 45 show the same change tendency with respect to the temperature change. Then, the computing unit 46 calculates the difference voltage VT1 ′, VT2 ′ between the two voltages VT1 ′, VT2 ′ and outputs the calculated value as the detected torque. And temperature compensation is reliably realized. In this case, both the magnetic paths of the coils 22 and 24 of the first group and the magnetic paths of the coils 23 and 25 of the second group include many common magnetic paths such as the outer core 21 and the inner core 33. The protrusions 21b and 21d and the coils 22 and 24 of the outer core 21 of the first group are also the same as the protrusions 21c and 21e and the coil 2 of the outer core 21 of the second group.
Since the reference numerals 3 and 25 are close to each other and have the same configuration, the accuracy of the temperature compensation is improved.

Further, in the above embodiment, the outer core 21 and the inner core 33 are made of laminated steel plates, so that the eddy current loss can be reduced and the magnetic resistance of the magnetic path can be reduced. As a result, the excitation frequency of the coils 22 to 25, that is, the oscillation frequency of the oscillator 41 can be increased while suppressing the eddy current loss to a small value, and a large change in inductance due to each of the coils 22 to 25 can be obtained. , The accuracy of torque detection can be improved.

In the above-described embodiment, two protrusions and two coils are provided for the outer cores belonging to the first and second groups. However, the protrusions and the coils for the outer cores belonging to the first and second groups are provided. May be provided one by one. For example, the first
Only the projection 21b and the coil 22 of the outer core 21 (or the projection 21d and the coil 24 of the outer core 21) are provided as the projection and the coil of the outer core belonging to the group, and the outer core 21 is provided as the projection and the coil of the outer core belonging to the second group. Only the protrusion 21e and the coil 25 (or the protrusion 21c and the coil 23 of the outer core 21) may be provided. in this case,
The protrusion 3c of the inner core 33 (or the protrusion 33b of the inner core 33) is omitted, and the protrusion 3 of the inner core 33 is omitted.
3b (or the protruding portion 33b of the inner core 33) only needs to be provided.

Conversely, three or more projections and three or more coils of the outer cores belonging to the first and second groups may be provided. In this case, the protrusions and coils of the outer core belonging to the first group and the protrusions and coils of the outer core belonging to the second group are alternately arranged at equal intervals along the circumferential direction on the inner peripheral surface of the housing 10. In addition, the coils belonging to each group may be connected in series between the resistors 42 and 43 and the ground as shown in FIG. Regarding the inner core, the protrusions 21b, 2 of the outer core 21 of the above embodiment are provided.
Like the set 1e and the set of protrusions 21c, 21d of the outer core 21, the inner core protrusions are respectively disposed between the pair of outer core protrusions that belong to the first and second groups and are adjacently paired. The inner core may be fixed to the sleeve 32 by disposing the inner core.

Further, in the above-described embodiment and modifications, the inner core 33 is fixed to the input shaft 12 side, and the outer core 21 and the coils 22 to 2 are fixed to the output shaft 13 side.
5 was fixed. However, the present invention does not
The relative positions of the outer core 21 and the output shaft 13 are determined by the protrusions 33 b and 33 c of the inner core 33 and the protrusions 21 b to 21 of the outer core 21.
e, the outer core 21 and the coils 22 to 2 on the input shaft 12 side.
5 while fixing the inner core 33 on the output shaft 13 side.
May be fixed.

[Brief description of the drawings]

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

FIG. 2 is a plan cross-sectional view of the torque detection device taken along line 2-2 of FIG.

FIG. 3 is a block diagram showing an example of a torque detection circuit diagram using the torque detection device.

FIG. 4 is a graph showing a relationship between a voltage value detected by the voltage detector of FIG. 3 and torque.

[Explanation of symbols]

Reference numeral 10: housing (first member), 12: input shaft, 13:
Output shaft, 15: torsion bar, 21: outer core, 2
1a: annular portion, 21b to 21e: protrusion, 22 to 25 ...
Coil, 32: sleeve (second member), 33: inner core (rotor), 33a: annular portion, 33b, 33c: protruding portion, 41: oscillator, 44, 45: voltage detector, 46: arithmetic unit.

Claims (1)

[Claims] An annular outer core provided so as to rotate integrally with one of an input shaft and an output shaft connected to each other by a torsion bar so as to be relatively rotatable; At least a first coil and a second coil, each of which is assembled at a predetermined interval along the axis, and radially inward of the first and second coils so as to rotate integrally with the other of the input shaft and the output shaft. An inner core formed at a position between the circumferential direction of the first and second coils and formed with a protruding portion protruding radially outward;
A torque detecting device for detecting a torque acting on the input shaft and the output shaft by a change in inductance of the first and second coils according to a relative position between the first and second coils and the protrusion of the inner core. .