JPH10142082A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor that can detect any one of disconnection, shortcircuiting, and rare short-circuiting. SOLUTION: Two torque values are detected based on the relative displacement between first and second sensor rings 21 and 22 and that between second and third sensor rings 22 and 23, and each detection value is corrected by a temperature compensation value that is detected by third and fourth sensor rings 23 and 24, thus obtaining a temperature-compensated main output and sub output. Then, it can be detected whether there is a failure according to the difference between the both, thus detecting a failure such as a rare short- circuiting that could not be detected by prior arts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a torque sensor for detecting a rotational torque acting between an input shaft and an output shaft as a change in magnetic resistance.

[0002]

2. Description of the Related Art Conventionally, as a torque sensor of an electric power steering device, a rotational torque acting between an input shaft and an output shaft connected via a torsion bar is used to measure a magnetic resistance caused by a torsion amount of the torsion bar. Some are detected from changes. As shown in Japanese Utility Model Application Laid-Open No. 1-158936 and Japanese Patent Application Laid-Open No. 4-76426, there is a torque sensor of this type including two detection coils to prevent a detection error due to a change in ambient temperature.

As shown in FIG. 15A, a torque sensor of the type shown in Japanese Utility Model Laid-Open Publication No. 1-158936 is provided with a compensation coil 72 for temperature compensation in addition to a detection coil 71 for detecting torque. It is. That is, the detection coil 71 is connected to the output shaft 7 connected through the torsion bar 75.
4 and the input shaft 73, torque is detected by a relative displacement between a first detection ring 76 attached to the output shaft 74 and a second detection ring 77 attached to the input shaft 73. The compensation coil 72 outputs a detection value corresponding to the ambient temperature by detecting the magnetic resistance of the second detection ring 77 and the third detection ring 78 attached to the input shaft 73. With such a configuration, the torque sensor can detect a high-accuracy torque from which an error due to a temperature change has been removed by calculating the difference between the output values of the detection coil 71 and the compensation coil 72.

As shown in FIG. 17A, a torque sensor of the type disclosed in Japanese Patent Application Laid-Open No. 4-76426 has two symmetric detection values (FIG. 17) from two detection coils 81 and 82.
(B)), and the torque is detected from the difference between the two. That is, the first detection coil 81 detects a relative displacement between the second detection ring 87 attached to the output shaft 84 and the first detection ring 86 attached to the input shaft 83,
The second detection coil 82 detects a relative displacement between the second detection ring 87 and a third detection ring 88 attached to the input shaft 83. For this reason, two symmetrical detection values C1 and C2 are obtained from the two detection coils 81 and 82, and by obtaining the torque from the difference between them, it is possible to detect an accurate torque from which an error due to a temperature change has been removed. .

[0005]

In each of the above types of torque sensors, when an abnormality occurs in a detection circuit including two coils of each torque sensor, it is necessary to immediately detect the abnormality. Such abnormalities in the detection circuit include disconnection, short-circuit, rare short-circuit (a phenomenon in which a normal detection value is not output due to water infiltration into the circuit, deterioration of wiring, damage to wiring, etc. (Normally lower) can be considered, but in the case of the torque sensor described above, disconnection and short-circuit can be detected, but it is difficult to detect rare short-circuit. This problem will be described using a torque sensor provided with the above-described compensation coil 72 for temperature compensation as an example. In this specification, the abnormalities of the coil (disconnection, short, rare short) refer not only to abnormalities of the coil itself, but also to abnormalities of a portion including a wiring portion of a detection circuit mainly including the coil. And

[0006] As shown in FIG.
And the outputs B1 and B2 of the compensation coil 72 are
1, via the voltage-current conversion circuit 83, the difference between the two is output as the main output B3. Similarly, output B1,
B2 passes through a differential amplifier circuit 82 and a voltage-current conversion circuit 84, and the difference between the two is output as a sub-output B4. As shown in FIG. 16A, the output B1 is a straight line having an inclination corresponding to the amount of torsion of the torsion bar 75, and the output B2 is a horizontal straight line corresponding to the ambient temperature. Then, the main and sub outputs B3 and B4 have basically the same value, and become a straight line having a slope shown in FIG.

In such an output, the detection coil 71
Alternatively, when the compensation coil 72 is disconnected, the output values B1 and B2 become abnormally large in the positive direction (B1-1, B2-1) as shown by the dashed line in FIG. The sub outputs B3 and B4 are both shown in FIG.
Fly upward as indicated by the dashed line (B3-1, B4-
1) Since the output current value exceeds the upper limit value F1, it is possible to detect that either the detection coil 71 or the compensation coil 72 is disconnected.

Similarly, when the detection coil 71 or the compensation coil 72 is short-circuited, the output values B1 and B2 become values close to 0 as shown by the two-dot chain line in FIG.
1-2, B2-2), and consequently the main and sub output B
Both B3 and B4 become values close to 0 (B3-2 and B4-2) as shown by the two-dot chain line in FIG. 16B, and fall below the lower limit value F2 of the output current value. It can be detected that one of the detection coil 71 and the compensation coil 72 is short-circuited.

However, when the detection coil 71 or the compensation coil 72 is short-circuited rarely, the output values B1 and B2 only have an error slightly offset downward as shown by the broken line in FIG. B1-3, B2-
3) As a result, both the main and sub outputs B3, 4
As shown by the broken line in FIG. 16B, only an error slightly offset downward occurs (B3-3, B4-
3). For this reason, since the output values B3-3 and B4-3 fall between the upper limit value F1 and the lower limit value F2 of the output current value, it is detected that the detection coil 71 or the compensation coil 72 is rarely short-circuited. Can not do.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a torque sensor capable of detecting an abnormality in any of disconnection, short circuit, and rare short circuit.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. The first aspect of the present invention is based on the relative rotation of an input shaft and an output shaft connected via a torsion bar. A torque sensor for detecting a rotational torque generated between the input shaft and the output shaft, wherein a first sensor portion and a third sensor portion attached to one of the input shaft and the output shaft; A second sensor unit attached to one of the other shafts and located between the first sensor unit and the third sensor unit, and a first sensor based on a relative rotation between the first sensor unit and the second sensor unit. First detection means for outputting a detection value, second detection means for outputting a second detection value based on a relative rotation between the second sensor section and the third sensor section, and a reference detection value based on an ambient temperature. Third detection means that outputs A main output unit that outputs a main output value based on the first detection value output from the first detection unit and the reference detection value output from the third detection unit; The second output
Sub-output means for outputting a sub-output value based on the detected value and the reference detection value output from the third detection means; the first detection value output from the first detection means and the second detection means Output value judging means for judging whether or not a difference value based on the second detection value output from the second detection value is within a predetermined allowable range; and the difference value is predetermined by the output value judging means. Abnormality processing means for performing abnormality processing when it is determined that the error is not within the allowable range.

A second aspect of the present invention is a torque sensor for detecting a rotational torque generated between the input shaft and the output shaft based on a relative rotation between the input shaft and the output shaft connected via a torsion bar. A first detection unit that outputs a first detection value based on a relative rotation between a first sensor unit attached to one of the output shafts and a second sensor unit attached to the other of the output shaft; A second sensor based on the relative rotation of a third sensor unit attached to one of the output shafts and a fourth sensor unit attached to the other of the output shafts
A second detection unit that outputs a detection value, a third detection unit that outputs a reference detection value based on an ambient temperature, and the first detection value output from the first detection unit and an output from the third detection unit. A main output unit that outputs a main output value based on the detected reference detection value, based on the second detection value output from the second detection unit and the reference detection value output from the third detection unit. A sub-output means for outputting a sub-output value by the first detecting means;
Output value determining means for determining whether a difference value based on a detected value and the second detected value output from the second detecting means is within a predetermined allowable range, and the output value determining means When the difference value is determined not to be within a predetermined allowable range, an abnormality processing means for performing an abnormality process is provided.

According to a third aspect of the present invention, in the torque sensor according to the first or second aspect, the output value judging unit outputs the main output value output from the main output unit and the main output value output from the sub output unit. It is characterized in that it is determined whether or not the difference value from the sub output value is within a predetermined allowable range. Claim 4
The torque sensor according to any one of claims 1 to 3, wherein the detected part where the third detecting means detects an ambient temperature is the first sensor part or the third sensor part. It is attached integrally to.

According to a fifth aspect of the present invention, in the torque sensor according to any one of the first to fourth aspects, the output value judging means includes a main output value output from the main output means and the main output value. The sub-output value output from the sub-output means, determine whether each is within the allowable range, if it is determined that it is not within the allowable range, disconnection performing abnormal processing by the abnormality processing means, It is provided with a short judgment means.

(Function) In the means of claim 1, the main output means outputs a first detection value based on a relative displacement between the input shaft and the output shaft output from the first detection means and an output from the third detection means. The main output value is output from the reference detection value based on the ambient temperature. Similarly, the sub output means outputs a sub output value based on the second detection value output from the second detection means and the reference detection value output from the third detection means. The output value determination unit determines whether a difference value based on the first detection value output from the first detection unit and the second detection value output from the second detection unit is within a predetermined allowable range. Is determined, and the abnormality processing means performs abnormality processing when it is determined that the difference value is not within a predetermined allowable range. Therefore, the detected torque is not only temperature-compensated, but also can be detected when there is an abnormality such as a rare short.

According to a first aspect of the present invention, in the first detecting means and the second detecting means, the total length of the torque sensor is shortened by also using the second sensor section. Accordingly, the first detection means outputs a first detection value based on the relative rotation between the first sensor section and the second sensor section, and similarly, the second detection means outputs the second detection section and the third sensor section. And outputs a second detection value based on the relative rotation of.

According to a second aspect of the present invention, the first detecting means and the second detecting means are completely separated, and the first detecting means performs the first detecting based on the relative rotation between the first sensor and the second sensor. A second detection unit that outputs a second detection value based on a relative rotation between the third sensor unit and the fourth sensor unit. Claim 3
Means for judging whether or not the difference value between the main output value output from the main output means and the sub output value output from the sub output means is within a predetermined allowable range. . That is, the abnormality is determined based on the output value after the temperature compensation.

According to a fourth aspect of the present invention, the detection portion for detecting the ambient temperature by the third detection means is integrally attached to the first sensor portion or the third sensor portion. Therefore, the total length of the torque sensor can be further reduced and the number of parts can be reduced. The means of claim 5 can reliably detect an abnormality such as a disconnection or a short circuit by determining whether the main output value and the sub output value are each within the allowable range.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. It is assumed that the torque sensor according to the present embodiment is applied to an electric power steering device. As shown in FIG. 1, the torque sensor according to the present embodiment mainly includes an input shaft 11, an output shaft 12, and a torsion bar 13.
And a sensor unit 20.

The input shaft 11 has its upper end connected to a handle (not shown) and rotates integrally with the handle. The input shaft 11 is formed of a hollow shaft, and one end of a torsion bar 13 penetrating through the hollow shaft is integrally connected to the input shaft 11 and a pin 14.
Is spline-engaged with the output shaft 12. The output shaft 12 is connected to the input shaft 11 and the needle bearing 15.
Are connected so as to be relatively rotatable. Therefore, the output shaft 12 can rotate relative to the input shaft 11 by the torsion bar 13 being twisted.

On the output shaft 12 side of the input shaft 11, two flange portions 11a extending in the radial direction are formed. Further, a flange 11 of the input shaft 11 is provided at a tip of the output shaft 12.
A notch 12a is formed at a position corresponding to a.
The flange 11a and the notch 12a are connected to the input shaft 1
The output shaft 12 is inserted with a predetermined gap in the relative rotation direction between the input shaft 11 and the output shaft 12, and constitutes a so-called manual stopper. The torque larger than the torsional reaction force of the torsion bar 13 is applied to the input shaft 11 and the output shaft. 12 and the flange 1
The input shaft 11 and the output shaft 12 are restricted from rotating relative to each other by a predetermined angle or more due to the contact between the side surfaces of the notch 1a and the notch 12a.

The input shaft 11 is supported by the upper housing 16 via a seal member 31 and a bearing 32, and the output shaft 1
2 is mounted on the lower housing 17 via a bearing 33. The output shaft 12 has an electric motor 65 (FIG. 3).
Gear 18 meshing with a pinion 19 rotated at
Are key-bound. Next, the configuration of the sensor unit 20 will be described. FIG. 2 shows the appearance of the sensor unit 20, and FIG. 3 shows an enlarged cross section of the sensor unit 20. The sensor unit 20 mainly includes a first sensor ring 21, a second sensor ring 22, and a third sensor ring 2
It comprises four sensor rings of third and fourth sensor rings 24 and three detection coils of a first detection coil 41, a second detection coil 42, and a third detection coil 43.

The above four sensor rings 21, 22, 2
Reference numerals 3 and 24 denote members made of a cylindrical magnetic material. The three sensor rings of the first sensor ring 21, the third sensor ring 23, and the fourth sensor ring 24 rotate integrally with the input shaft 11. And the second sensor ring 2
2 rotates integrally with the output shaft 12.

More specifically, rectangular teeth 21a are formed at an upper end of the first sensor ring 21 at a constant pitch. The first sensor ring 21 is fitted and fixed to the outer periphery of the flange portion 11a of the input shaft 11 via a nonmagnetic magnetic shielding spacer 26, and is also fixed by a pin 26a. At the upper end and the lower end of the second sensor ring 22, rectangular teeth 22a and 22b having a constant pitch equal to the teeth 21a of the first sensor ring 21 are formed. The tooth part 22a is opposed to the tooth part 21a of the first sensor ring 21, and the tooth part 22b is a third tooth part described later.
It faces the tooth portion 23a of the sensor ring 23. The second sensor ring 22 is fitted and fixed to the outer periphery of the distal end of the output shaft 12 via a nonmagnetic magnetic shielding spacer 27, and is also fixed by a pin 27a.

At the lower end of the third sensor ring 23, rectangular teeth 23a having a constant pitch equal to the teeth 22b of the second sensor ring 22 are formed. Tooth 23a
Is the tooth portion 22b of the second sensor ring 22 as described above.
And is facing. The third sensor ring 23 is fitted and fixed to the outer periphery of the input shaft 11 via a nonmagnetic magnetic shielding spacer 28, and is also fixed by a pin 28a. The lower end of the magnetic shielding spacer 28 is positioned by a circlip 34.

At the lower end of the fourth sensor ring 24, a tooth portion 24a having a smaller number of teeth than the tooth portion 23a of the third sensor ring 23 is formed. The teeth 24a face the upper end of the third sensor ring 23 where the teeth 23a are not formed. The fourth sensor ring 24 is connected to the input shaft 1
A non-magnetic magnetic shielding spacer 29, 30 is inserted into and fixed to the outer periphery of 1. The magnetic shielding spacer 29
The third sensor ring 23 and the fourth sensor ring 24 are located between the magnetic shield spacer 28 and the magnetic shield spacer 30.
Are positioned at a predetermined interval r2. The upper end side of the magnetic shielding spacer 30 is positioned by a circlip 35.

As shown in FIG. 2, the upper end of the first sensor ring 21 and the lower end of the second sensor ring 22 are coaxially arranged with a predetermined gap r1 in the axial direction. The overlap length of the tooth portions 21a and 22a in the circumferential direction (hereinafter referred to as wrap amount H1) is determined when the handle is in a neutral position (when no torque acts between the input shaft 11 and the output shaft 12). In), the lap amount is set to be a predetermined lap amount H0.

Similarly, the upper end of the second sensor ring 22 and the lower end of the third sensor ring 23 are coaxially arranged with a predetermined gap r1 in the axial direction. The lap amount H2 between the teeth 22b and the teeth 23a is set to be a predetermined lap amount H0 when the steering wheel is in the neutral state, similarly to H1. As shown in FIG. 2, the overlapping side of the teeth 22b and 23a and the teeth 21
a, 22a are opposite to the side where they overlap. Therefore, if relative rotation occurs between the input shaft 11 and the output shaft 12 and the wrap amount H1 of the tooth portions 21a and 22a increases,
If the wrap amount H2 of the tooth portions 22b and 23a decreases at the same rate, and if the wrap amount H1 of the tooth portions 21a and 22a decreases,
The wrap amount H2 of the tooth portions 22b and 23a increases at the same rate.

First detection coil 41, second detection coil 4
The three detection coils of the second and third detection coils 43 are fixed to the upper housing 16 via the coil guide 38. The coil guide 38 is an annular member made of a magnetic material, and guide ring portions 38a, 38b, 38
c, 38d. Each guide ring portion 38a, 3
8b, 38c, and 38d are fixed so as to face the first to fourth sensor rings 21, 22, 23, and 24, respectively.
The teeth 21a and the teeth 22a are arranged at positions facing each other by being wound in a ring shape between the teeth 8a and 38b.

Similarly, the second detection coil 42 is annularly wound between the guide ring portions 38b and 38c, and is disposed at a position where the tooth portion 22b and the tooth portion 23a face each other. It is wound annularly between the guide ring portions 38c and 38d, and the upper end of the third sensor ring 23 and the tooth portion 24
a are arranged at positions facing each other. With such a configuration, the first detection coil 41, the second detection coil 42,
The third detection coil 43 forms magnetic paths R1, R2, R3 between the coil guide 38 and the first to fourth sensor rings 21, 22, 23, 24.

Next, the electrical configuration of the present embodiment will be described with reference to FIG. The first detection coil 41, the second detection coil 42, and the third detection coil 43 form a bridge circuit. One end of each detection coil 41, 42, 43 is connected and grounded, and the other end is connected. It is connected to the oscillator 44 via resistors 46, 47 and 48 having a predetermined resistance value. The oscillator 44 generates a constant voltage AC having a predetermined frequency. The peak hold circuit 51 is connected between the first detection coil 41 and the resistor 46. Similarly, a portion between the second detection coil 42 and the resistor 47 is connected to the peak hold circuit 52, and the third detection coil 43
The resistor 48 is connected to the peak hold circuit 53. The peak hold circuits 51, 52, and 53 hold and output the maximum value of the sine waveform output from each of the detection coils 41, 42, and 43.

The peak hold circuit 51 includes a differential amplifier 5
4 non-inverting input terminals. The peak hold circuit 53 is branched into two, one of which is connected to the inverting input terminal of the differential amplifier 54, and the other is connected to the non-inverting input terminal of the differential amplifier 55. Peak hold circuit 52
Are connected to the inverting input terminal of the differential amplifier 55.
An output terminal of the differential amplifier 54 is connected to a voltage-current conversion circuit 56, and an output terminal of the voltage-current conversion circuit 56 is connected to a control device 60. The output terminal of the differential amplifier 55 is connected to the voltage-current conversion circuit 57, and the output terminal of the voltage-current conversion circuit 57 is connected to the control device 60. Therefore, the first detection coil 41, the second detection coil 4
The output values of the second and third detection coils 43 are A1, A
2, A3, the main output A4 output from the voltage-current conversion circuit 56 is A4 = A1-A3 + α,
Sub output A5 output from voltage-current conversion circuit 57
Is A5 = A3-A2 + α. α is an offset value. The formulas of the main output A4 and the sub output A5 are as follows:
As is clear from the configuration of the sensor unit 20, the main output A4 and the sub output A5 have basically the same value in a normal state. Further, the abnormality of the first detection coil 41, that is, the abnormality of the output A1, affects only the main output A4 and does not affect the sub-output A5. Conversely, the abnormality of the second detection coil 42, that is, the abnormality of the output A2 affects only the sub-output A5, and the main output A
No. 4 is not affected.

The control unit (ECU) 60 includes a central processing unit (CPU) 62, an interface 61, and a memory 63.
The main output A4 and the sub output A5 are input via the interface 61. The memory 63 has a main output A4
Further, a program for controlling the electric motor 65 based on the sub output A5, a program for performing an abnormality process such as turning on a warning lamp 66 when an abnormality occurs in a torque detection circuit described later, and the like are stored.

Next, the operation of the present embodiment will be described. FIG.
The solid line in (a) shows each output A1, of the first detection coil 41, the second detection coil 42, and the third detection coil 43 in a normal state.
A2 and A3 are shown, and the solid line in FIG. 4B shows the main output A4 and the sub-output A5 in a normal state.

When the steering wheel is in a neutral state and the steering torque is 0, no relative rotation occurs between the input shaft 11 and the output shaft 12, so that the first sensor ring 21
The lap amount H1 between the tooth portion 21a of the second sensor ring 22 and the tooth portion 22a of the second sensor ring 22 is an initial value H0, and similarly, the tooth portion 22b of the second sensor ring 22 and the tooth portion 2 of the third sensor ring 23.
The lap amount H2 of 3a is also the initial value H0. In this state, the outputs A1, A2, A3 of the respective detection coils 41, 42, 43
Have the same value, and the main output A4 and the sub output A5 have the offset value α.

When the steering wheel is steered in this state, the input shaft 11 is rotated, whereby the torsion bar 13 is twisted, and relative rotation occurs between the input shaft 11 and the output shaft 12. Accordingly, relative rotation occurs between the first sensor ring 21, the second sensor ring 22, and the third sensor ring 23. That is, the tooth portion 21a of the first sensor ring 21
When the lap amount H1 of the tooth portion 22a of the second sensor ring 22 is displaced in the increasing direction, the wrap amount H2 of the tooth portion 22b of the second sensor ring 22 and the tooth portion 23a of the third sensor ring 23 decrease. And the tooth portions 21a and 22
a is displaced in a direction in which the lap amount H1 of the tooth a decreases.
The wrap amount H2 between the tooth 2b and the tooth portion 23a is displaced in an increasing direction. Since the fourth sensor ring 24 is fixed to the input shaft 11 similarly to the third sensor ring 23, no relative rotation occurs between them.

Therefore, the outputs A1 and A2 of the first detection coil 41 and the second detection coil 42 have values that change symmetrically,
The output A3 of the third detection coil 43 has a constant value. Then, the main output A4 and the sub output A5 have the same value. The main output A4 and the sub output A5 are
It is set so as to be always between the upper limit value F1 and the lower limit value F2 in a normal use range. The straight lines of the outputs A1 to A5 in the normal state are connected to the resistors 46, 47,
By changing the resistance values of the resistors 48 and the operational amplifiers 54 and 55, fine adjustment is performed so that a desired straight line is obtained.

Next, a case where an abnormality occurs in the first detection coil 41, the second detection coil 42, and the third detection coil 43 will be described in order. [1. When the first detection coil 41 or the second detection coil 42 is short-circuited] When the first detection coil 41 is short-circuited, the output A1 jumps to a value close to 0 as indicated by A1-1 in FIG. Therefore, the main output A4 also jumps to a value close to 0, and falls below the lower limit value F2 (A4 in FIG. 4B).
1). Therefore, by detecting that the output A1 has deviated from the lower limit F2, it is possible to detect an abnormality due to a short circuit of the first detection coil 41. Upon detecting this abnormality, the control device 60 performs an abnormality process such as stopping the electric motor 65 and turning on the warning lamp 66.

When the second detection coil 42 is short-circuited,
As shown in A2-1 of FIG. 5A, the output A2 flies to a value close to 0, so that the sub output A5 flies to a large value in the positive direction (A5-1 of FIG. 5B), Above the value F1, an abnormality due to a short circuit of the second detection coil 42 can be detected. By detecting this abnormality, the control device 60 performs the same abnormality processing as when the first detection coil 41 is short-circuited.

As described above, the abnormality caused by the short circuit of the first detection coil 41 or the second detection coil 42 is determined by determining whether each of the main output A4 and the sub output A5 is within the allowable range from the lower limit F2 to the upper limit F1. It can be detected by judgment. [2. When the first detection coil 41 or the second detection coil 42 is disconnected] When the first detection coil 41 is disconnected, FIG.
As shown in A1-2 of (a), since the output A1 flies to a large value in the plus direction, the main output A4 also flies in the plus direction and exceeds the upper limit F1 (A4 in FIG. 6B).
-2) It is possible to detect an abnormality due to disconnection of the first detection coil 41. By detecting this abnormality, the control device 60 performs the same abnormality processing as when the first detection coil 41 is short-circuited.

When the second detection coil 42 is disconnected, FIG.
Since the output A2 jumps to a large value in the plus direction as indicated by A2-2 in (a), the main output A5 becomes a value close to 0 (A5-2 in FIG. 5B), and the lower limit value F2 is reduced. It is possible to detect an abnormality due to the disconnection of the second detection coil 42 when the second detection coil 42 drops. By detecting this abnormality, the control device 60 performs the same abnormality processing as when the first detection coil 41 is short-circuited.

As described above, the abnormality caused by the disconnection of the first detection coil 41 or the second detection coil 42 is caused by the main output A4 and the sub output A5 each having the lower limit value F2 to the upper limit value F1. It can be detected by judging whether it is within the allowable range. [3. When the first detection coil 41 or the second detection coil 42 is short-circuited rarely] When the first detection coil 41 is short-circuited rarely, as shown in A1-3 of FIG.
1 fluctuates and becomes a straight line offset from a normal value.
Therefore, the main output A4 also fluctuates and becomes a straight line (A4-3 in FIG. 7B) offset from the normal value. on the other hand,
Since the second detection coil 42 operates normally, the sub output A5 becomes a normal straight line. Therefore, an error ΔI occurs between the normal output A5 and the abnormal output A4-3. Therefore, by determining whether the error ΔI generated between the main output A4 and the sub output A5 is within an allowable range,
An abnormality due to a rare short of the first detection coil 41 can be detected. By detecting this abnormality, the control device 60 performs abnormality processing such as stopping the electric motor 65 and turning on the warning lamp 66 as in the case where the first detection coil 41 is short-circuited.

Similarly, when the second detection coil 42 is short-circuited rarely, the output A2 fluctuates and offsets (A2-3 in FIG. 7A), so that the sub output A5 also fluctuates and offsets (FIG. 7A A2-3))). Therefore, an error ΔI occurs between the normal main output A4 and the abnormal sub-output A5-3. Therefore, the main output A4 and the sub output A5
By determining whether the error ΔI occurring between the second detection coil and the second detection coil is within an allowable range, it is possible to detect an abnormality due to a rare short of the second detection coil. By detecting this abnormality, the control device 60 performs the same abnormality processing as when the first detection coil 41 is short-circuited.

As described above, the abnormality caused by the rare short of the first detection coil 41 or the second detection coil 42 is determined by determining whether the error ΔI generated between the main output A4 and the sub output A5 is within an allowable range. Can be detected by [4. When the third detection coil 43 is short-circuited] When the third detection coil 43 for temperature compensation is short-circuited, FIG.
As shown in A3-4 of (a), the output A3 flies to a value close to zero. For this reason, the main output A4 flies in the plus direction and exceeds the upper limit F1 (A4 in FIG. 8B).
4). The sub-output A5 jumps to a value close to 0, and falls below the lower limit F2 (A5-4 in FIG. 8B). Control device 60
When this abnormality is detected, abnormality processing such as stopping the electric motor 65 and turning on the warning lamp 66 is performed as in the case where the first detection coil 41 is short-circuited.

As described above, the short-circuit of the third detection coil 43 can be detected by determining whether each of the main output A4 and the sub-output A5 is within the allowable range from the lower limit F2 to the upper limit F1. [5. When the third detection coil 43 is disconnected] When the third detection coil 43 is disconnected, the output A3 flies in the positive direction as indicated by A3-5 in FIG. 9A. For this reason,
The main output A4 jumps to a value close to 0 and falls below the lower limit value F2 (A4-5 in FIG. 9B). The sub output A5 flies in the plus direction and exceeds the upper limit F1 (A in FIG. 9B).
5-5). Upon detecting this abnormality, the control device 60 performs the same abnormality processing as when the first detection coil 41 is short-circuited.

As described above, the disconnection of the third detection coil 43 is as follows.
Each of the main output A4 and the sub output A5 is the lower limit value F2.
Can be detected by judging whether or not it is within an allowable range from to the upper limit F1. [6. When the third detection coil 43 is short-circuited rarely]
When the detection coil 41 is short-circuited rarely, FIG.
As shown in A3-6, the output A3 fluctuates and becomes a straight line offset from the normal value. Therefore, the main output A
4 and the sub-output A5 fluctuate in the opposite directions to each other, and are offset from normal values by straight lines (A4-6, A4-6 in FIG.
5-6). Therefore, an error ΔI occurs between the main output A4-6 and the sub output A5-6. For this reason, by determining whether the error ΔI generated between the main output A4 and the sub output A5 is within an allowable range, it is possible to detect an abnormality due to a rare short of the third detection coil 43. By detecting this abnormality, the control device 60 performs abnormality processing such as stopping the electric motor 65 and turning on the warning lamp 66 as in the case where the first detection coil 41 is short-circuited.

Next, the first detection coil 41 and the second
An outline of a program for detecting an abnormality of the detection coil 42 and the third detection coil 43 will be described with reference to a flowchart of FIG. In step 100, the abnormality detection program inputs the main output A4 and the sub output A5. Then, in step 102, the main output A4 is set to the lower limit value F.
It is determined whether it is between 2 and the upper limit F1. When the main output A4 is between the lower limit F2 and the upper limit F1 (YES), the process proceeds to step 104. If the main output A4 is not between the lower limit value F2 and the upper limit value F1 (NO), it is considered that any of the three detection coils 41, 42, 43 has a short-circuit or disconnection abnormality. The process proceeds to 110, where abnormal processing such as stopping of the electric motor 65 and turning on the warning lamp 66 is performed, and then the abnormality detection program is terminated.

In step 104, similarly to step 102, it is determined whether or not the sub output A5 is between the lower limit value F2 and the upper limit value F1. If the sub output A5 is between the lower limit F2 and the upper limit F1 (YES), the process proceeds to step 106. When the sub output A5 is not between the lower limit F2 and the upper limit F1 (NO), the three detection coils 41,
Since it is considered that an abnormality such as a short circuit or a disconnection has occurred in any of 42 and 43, the routine proceeds to step 110 to perform abnormality processing, and then ends this abnormality detection program.

In step 106, it is determined whether or not the difference ΔI between the main output A4 and the sub output A5 is within an allowable range. This permissible range is determined in advance by performing experiments. When the difference ΔI is within the allowable range (YE
S), proceed to step 108. When the difference ΔI is not within the allowable range (NO), the three detection coils 41,
Since it is considered that an abnormality due to a rare short has occurred in any of 42 and 43, the routine proceeds to step 110 to perform abnormality processing, and then ends this abnormality detection program.

In step 108, since the values of the main output A4 and the sub output A5 are considered to be normal by the above steps, both outputs are output to control the electric motor 65, and this abnormality detection program is executed. finish. However, only the main output A4 is actually used for controlling the electric motor 65. Thus, the main output A4 and the sub output A5 which have passed through the abnormality detection program described above.
Is based on the output value of the third detection coil 43, the error due to the influence of the ambient temperature is removed, and all of the three detection coils 41, 42, and 43 have high reliability without any abnormality.

As described above, the torque sensor according to the present embodiment detects the temperature-compensated main output A4 and sub-output A5 from the two torque detection values A1 and A2 and one temperature compensation value A3. An abnormality of the torque detection circuit is detected from the two outputs A4 and A5. In the present embodiment, the three sensor rings for detecting the two torque detection values A1 and A2 are the sensor rings 21, 22, and 23, and the sensor ring 22 is used to determine the two torque values A1 and A2. The dual use achieves downsizing of the torque sensor and reduction of the number of parts (corresponding to claim 1). However, the torque detection values A1 and A2 may be completely separated, and the torque value may be detected from the relative displacement of two sets of sensor rings, one set each.
The means for detecting the torque value from the relative displacement of the two sets of sensor rings corresponds to the first and second detecting means. Further, when this embodiment corresponds to claim 2, first and second sensor rings 21 and 22 correspond to the first and second sensor units, and second and third sensor rings correspond to the third and fourth sensor units. Sensor ring 2
2,23 correspond). In this case, the torque detection values A1,
The number of sensor rings for obtaining A2 is four (five when temperature compensation is added).

Further, the torque sensor of the present embodiment
In order to detect the two torque detection values A1 and A2, the first sensor ring 21 and the third sensor ring 2
3 is attached, and the second sensor ring 22 is attached to the output shaft 12. On the contrary, the second sensor ring is attached to the input shaft 11, and the first sensor ring and the third sensor ring are attached to the output shaft 12. It is good also as a structure attached.

Further, the torque sensor according to the present embodiment
The main output A4 and the sub output A5 after temperature compensation are compared to detect a rare short (corresponding to claim 3). By comparing the two torque detection values A1 and A2, a rare short is detected. The temperature may be compensated after detecting and judging that it is normal. Next, a second embodiment will be described. In the torque sensor according to the first embodiment, in order to prevent the axial length of the torque sensor from being longer than that of the conventional one, the first sensor ring 21 is connected to the input shaft 11 serving as a manual stopper. Is mounted on the outer periphery of the flange portion 11a, but in the second embodiment, the overall length is further reduced.

In the first embodiment, the first to the third
The teeth 21a, 22a, 22b, 23a are formed at the upper end or the lower end of the sensor rings 21, 22, 23, and the change of the wrap amount H1, H2 of the sensor ring is detected in the axial direction. In the following second embodiment, the first to third sensor rings are arranged so as to overlap each other, and a change in the wrap amount of the sensor ring is detected in the radial direction. Further, the third sensor ring 23 and the fourth sensor ring 24 of the first embodiment are integrated.
In the first embodiment and the second embodiment, only parts different from the first embodiment will be described, and the other same parts will be denoted by the same reference numerals as those in the first embodiment and described. Omitted.

FIG. 12 shows the second embodiment. FIG. 13A is a view taken in the direction of the arrow A in FIG.
(B) is a BB section of FIG. 11, and (c) is a CC section of FIG. FIG. 14A is a top view of the third sensor ring 230, and FIG. 14B is a side view of the third sensor ring 230. Sensor unit 2 according to second embodiment
00 is mainly the first to third sensor rings 2 in order from the bottom.
10, 220, 230 and the first to third detection coils 41,
The third sensor ring 230 is composed of three detection coils 42 and 43, and the third sensor ring 230 also serves as the third sensor ring 23 and the fourth sensor ring 24 of the first embodiment.

At the upper end of the first sensor ring 210, a trapezoidal tooth portion 210a having one side inclined at a constant pitch is formed. The first sensor ring 210 is fitted and fixed to the outer periphery of the flange portion 11a of the input shaft 11 via a nonmagnetic magnetic shielding spacer 260, and is also fixed by a pin 260a. Second sensor ring 2
At the upper end and the lower end of 20, there are formed rectangular teeth 220a and 220b having a constant pitch equal to the teeth 210a of the first sensor ring 210 described above. The second sensor ring 220 has a smaller diameter than the first sensor ring 210 and is located on the inner side.
Overlaps with the tooth portion 210a of the first sensor ring 210, and the tooth portion 220b
Of the tooth 230a. The second sensor ring 220 is fitted and fixed to the outer periphery of the distal end of the output shaft 12 via a nonmagnetic magnetic shielding spacer 270, and is also fixed by a pin 270a.

At the lower end of the third sensor ring 230, a trapezoidal tooth portion 230a having one side inclined at a constant pitch equal to the tooth portion 220a of the second sensor ring 220 is formed. The third sensor ring 230 has the same diameter as the first sensor ring 210 and the second sensor ring 22
0. The direction of the inclination formed on the teeth 230a is opposite to the direction of inclination of the teeth 210a as shown in FIG.
At the upper end of the third sensor ring 230, a tooth portion 240 corresponding to the fourth sensor ring 24 of the first embodiment is formed. The tooth part 240 is the tooth part 210 described above.
a, 220a, 220b, 230a are smaller than the number of teeth (in the case of the second embodiment, 2
Sheet).

The third sensor ring 230 is connected to the input shaft 1
1 is fitted and fixed on the outer periphery of the device 1 via a magnetic shielding spacer 280 made of a non-magnetic material, and is also fixed by a pin 280a. The lower end of the magnetic shielding spacer 280 is positioned by the circlip 340. A magnetic shield spacer 290 made of a non-magnetic material is attached above the magnetic shield spacer 280, and the upper end of the magnetic shield spacer 290 is positioned by the circlip 350.

As shown in FIG. 13B, the upper side of the first sensor ring 210 and the lower side of the second sensor ring 220 are coaxially arranged with a predetermined gap r3 in the radial direction. . Further, the tooth portion 210a and the tooth portion 220
The lap amount H3 at which a overlaps with a in a triangular shape is set to be a predetermined initial amount H0 when the steering wheel is neutral. Similarly, the upper side of the second sensor ring 220 and the lower side of the third sensor ring 230 are coaxially arranged with a predetermined gap r3 in the radial direction. Also,
The wrap amount H4 between the tooth portion 210a and the tooth portion 220a is:
When the steering wheel is in the neutral position, the predetermined initial amount H0 is set.

As shown in FIG. 13A, the teeth 22
0b, 230a and the above-described tooth portion 210
a, 220a are on the side opposite to the side on which they overlap.
Therefore, when the input shaft 11 and the output shaft 12 rotate relative to each other, if the wrap amount H3 of the tooth portions 210a and 220a increases, the wrap amount H4 of the tooth portions 220b and 230a decreases at the same rate. Wrap amount H of parts 210a and 220a
3 decreases, the wrap amount H of the tooth portions 220b and 230a
4 increase at the same rate.

First detecting coil 41, second detecting coil 4
The configuration of the three detection coils of the second and third detection coils 43 is as follows.
This is basically the same as the first embodiment. However, the guide ring portions 38a, 38b, 38 of the coil guide 38
c and 38d respectively represent the first sensor ring 210,
Second sensor ring 220, distal end of tooth portion 230a of third sensor ring 230, tooth portion 2 of third sensor ring 230
It is fixed so as to face 40. In addition, the first detection coil 41 is disposed opposite to the position where the tooth portion 210a and the tooth portion 220a overlap, the second detection coil 42 is disposed opposite to the position where the tooth portion 220b and the tooth portion 230a overlap, The third detection coil 43 is connected to the third sensor ring 23.
It is located at a position facing the distal end of the zero tooth portion 240.

With the configuration described above, the torque sensor according to the second embodiment has both functions of temperature compensation and detection of an abnormality of the detection coil including a rare short circuit, as in the first embodiment. Thus, the total length of the torque sensor can be reduced. Further, while the number of sensor rings is four in the first embodiment, it is three in the second embodiment, so that the number of parts can be reduced and the cost can be reduced.

[0063]

As described above, according to the first aspect of the present invention, two torque values are detected by the first and second detecting means, and the respective detected values are detected by the third detecting means. Correction is made by the temperature compensation value to obtain a temperature-compensated main output and sub-output. Further, since it is possible to detect whether or not there is an abnormality based on a difference between the two, there is an effect that an abnormality such as a rare short which cannot be detected conventionally can be detected.

In the first aspect of the present invention, since the second sensor section is used as the first and second detection sections, the total length of the torque sensor can be shortened and the number of parts can be reduced because three sensor sections are used. . The means of claim 2 is
By completely separating the first and second detection means, the above effect can be obtained with a simple configuration.

According to a fourth aspect of the present invention, since the detection portion for detecting the ambient temperature is integrally attached to the first sensor portion or the third sensor portion, the total length of the torque sensor can be further reduced. The number of parts can be reduced. The means of claim 5 can reliably detect an abnormality such as a disconnection or a short circuit by judging whether or not the main output value and the sub output value are within allowable ranges. Therefore, the present invention can detect not only an accurate torque value with temperature compensation, but also any abnormality such as short-circuit, disconnection, and rare short-circuit.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an appearance of a sensor unit according to the first embodiment.

FIG. 3 is a diagram illustrating a vertical cross section of a sensor unit according to the first embodiment.

FIG. 4 is a diagram showing an electrical configuration of the first embodiment.

FIG. 5 is a diagram showing a normal state and a case where the first or second detection coil is short-circuited in the first embodiment.

FIG. 6 is a diagram illustrating a case where the first or second detection coil is disconnected in the first embodiment.

FIG. 7 is a diagram showing a case where the first or second detection coil is rarely short-circuited in the first embodiment.

FIG. 8 is a diagram illustrating a case where a third detection coil is short-circuited in the first embodiment.

FIG. 9 is a diagram illustrating a case where a third detection coil is disconnected in the first embodiment.

FIG. 10 is a diagram showing a case where the third detection coil has a rare short-circuit in the first embodiment.

FIG. 11 is a flowchart showing an outline of the operation of the first embodiment.

FIG. 12 is a longitudinal sectional view of a torque sensor according to a second embodiment of the present invention.

FIG. 13 is a diagram showing a detailed portion of FIG. 12;

FIG. 14 is a diagram illustrating a third sensor ring according to the second embodiment.

FIG. 15 is a diagram showing a first example of the related art.

FIG. 16 is a diagram for describing a problem of the related art.

FIG. 17 is a diagram showing a second example of the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Input shaft 12 Output shaft 13 Torsion bar 20 Sensor part 21, 22, 23, 24 First, second, third, fourth
Sensor ring 41, 42, 43 First, second, third coil

Claims (5)

[Claims] 1. A torque sensor for detecting a rotation torque generated between an input shaft and an output shaft based on a relative rotation between an input shaft and an output shaft connected via a torsion bar, wherein the input shaft and the output A first sensor unit and a third sensor unit attached to one of the shafts, and an intermediate unit attached to one of the input shaft and the output shaft and located between the first sensor unit and the third sensor unit; A second sensor unit; a first detection unit that outputs a first detection value based on a relative rotation between the first sensor unit and the second sensor unit; A second detection unit that outputs a second detection value based on the relative rotation, a third detection unit that outputs a reference detection value based on an ambient temperature, and the first detection value output from the first detection unit. From the third detecting means A main output unit that outputs a main output value based on the input reference detection value, and a second detection value output from the second detection unit and a reference detection value output from the third detection unit. A sub-output means for outputting a sub-output value based on the first detection value output from the first detection means and a second detection value output from the second detection means, An output value determining means for determining whether or not the difference value is within a predetermined allowable range; and an abnormality performing abnormal processing when the output value determining means determines that the difference value is not within a predetermined allowable range. A torque sensor comprising processing means. 2. A torque sensor for detecting a rotation torque generated between said input shaft and said output shaft based on a relative rotation between an input shaft and an output shaft connected via a torsion bar, wherein said input shaft and said output A first detection unit that outputs a first detection value based on a relative rotation between a first sensor unit attached to one of the shafts and a second sensor unit attached to the other, the input shaft and the output shaft A second detection unit that outputs a second detection value based on a relative rotation between a third sensor unit attached to one of the third sensor unit and a fourth sensor unit attached to the other, and a reference detection value based on the ambient temperature. And a main output unit that outputs a main output value based on the first detection value output from the first detection unit and the reference detection value output from the third detection unit. , A sub-output unit that outputs a sub-output value based on the second detection value output from the second detection unit and the reference detection value output from the third detection unit; Output value determining means for determining whether a difference value based on the first detected value and the second detected value output from the second detecting means is within a predetermined allowable range, An abnormality processing unit for performing abnormality processing when the output value determining unit determines that the difference value is not within a predetermined allowable range. 3. An output value judging means, wherein a difference value between the main output value output from the main output means and the sub output value output from the sub output means falls within a predetermined allowable range. The torque sensor according to claim 1, wherein it is determined whether or not there is a torque sensor. 4. The apparatus according to claim 1, wherein the detected part for which the third detecting means detects the ambient temperature is integrally attached to the first sensor part or the third sensor part. The torque sensor according to claim 3. 5. The output value judging means judges whether or not the main output value output from the main output means and the sub output value output from the sub output means are respectively within an allowable range. 5. The apparatus according to claim 1, further comprising: a disconnection / short determination unit that performs an abnormality process by the abnormality processing unit when it is determined that the value is not within the allowable range. 6. 2. The torque sensor according to 1.