JP2001091375A - Torque sensor and electrically-driven steering device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structures on the input shaft side and output shaft side in comparison with a conventional torque sensor provided with a pair of rings made of a magnetic body provided with rectangular tooth parts at their faces. SOLUTION: This electrically-driven steering device is provided with first and second magnetic wave lines 11 and 12 provided for an input shaft 1 along its circumferential direction, a third magnetic wave line 13 provided for an output shaft 3 along its circumferential direction, and first to third magnetic sensors 21, 22, and 23 each fixed opposingly to the magnetic wave lines 11-13. The first and second magnetic wave lines 11 and 12 are differently located in the direction of rotation of the input shaft 1, torque added to the input shaft 1 is obtained on the basis of each detected value detected by the first and third magnetic sensors 21 and 23. The angle of rotation of the input shaft 1 is obtained on the basis of each detected value detected by the first and second magnetic sensors 21 and 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor for detecting a torque applied to a torsion bar by rotating an input shaft connected to the torsion bar based on a torsion angle generated in the torsion bar, and an electric steering apparatus using the same. About.

[0002]

2. Description of the Related Art As an electric steering apparatus, for example, an input shaft connected to a steered wheel for steering, and an upper end coaxially connected to a lower end of the input shaft via a torsion bar, An output shaft connected to a steering mechanism connected to the wheels, a torque sensor that detects a torque applied to the input shaft by rotating the steered wheels by a twist angle generated in the torsion bar, and a detection result of the torque sensor. A transmission mechanism for decelerating the rotation of a steering assist motor driven and transmitting the output to the output shaft, assisting the operation of the steering mechanism according to the rotation of the steered wheels by the rotation of the motor, and It is configured so as to reduce the labor burden on the driver. Further, a steering angle midpoint of the steered wheels is obtained by a rotation angle sensor such as a potentiometer, and drive control of the motor according to the steered angle of the steered wheels is also performed.

[0003] As a torque sensor of this electric steering device, a non-contact type torque sensor is known as described in Japanese Patent Publication No. 07-021433.

This non-contact type torque sensor is arranged around one of an input shaft and an output shaft, and has a pair of magnetic rings having rectangular teeth formed on the end face in the circumferential direction. An annular torque detection coil disposed around the body ring, wherein when the magnetic ring is relatively rotated in response to the torsion of the torsion bar, the facing area of the teeth changes, and the torque detection coil The steering torque is detected by detecting a change in the impedance of the steering wheel.

[0005]

However, in a conventional non-contact type torque sensor, an annular torque detecting coil is disposed around a magnetic ring, and a rectangular torque detecting coil and an end face are formed on the end face. Since there is provided a pair of magnetic rings provided in the circumferential direction with teeth having a shape, the structure is complicated and there is a demand for a reduction in cost. In addition, since the conventional non-contact type torque sensor described above detects only the torque applied to the input shaft, the rotation angle sensor detects the steering angle of the steered wheels, and a steering assist In the conventional electric steering device configured to drive the motor and assist the steering, it is necessary to use a rotation angle sensor such as a potentiometer separately from the torque sensor, and the structure of the electric steering device is It was complicated.

The present invention has been made in view of the above-described circumstances, and has first and second magnetic waves along the circumferential direction of the input shaft, and third magnetic waves along the circumferential direction of the output shaft. Articles,
First and second magnetic sensors for detecting the strength of each magnetic field generated near the first and second magnetic streaks, respectively, and the strength of the magnetic field generated near the third magnetic streak Third to detect
And a torque and rotation angle are calculated based on the detection values detected by these magnetic sensors, thereby simplifying the structure as compared with a conventional torque sensor having a coil and a ring made of a magnetic material. It is an object of the present invention to provide a torque sensor capable of detecting a rotation angle and an electric steering device which does not need to use a rotation angle sensor separate from the torque sensor.

Further, a fourth magnetic streak along the circumferential direction of the input shaft, a fifth magnetic streak along the circumferential direction of the output shaft, and the strength of a magnetic field generated near the fourth magnetic streak. The fourth to detect
And a fifth magnetic sensor for detecting the intensity of a magnetic field generated near the fifth magnetic streak, wherein the position of the fourth magnetic sensor is different in the direction of rotation of the input shaft. With the two torque sensors, the rotation angle and torque of the input shaft can be determined with high accuracy based on the detection values detected by these magnetic sensors. An object of the present invention is to provide a torque sensor whose structure can be simplified as compared with the above, and an electric steering device which does not require the use of a rotation angle sensor separate from the torque sensor.

It is another object of the present invention to provide a torque sensor capable of detecting a magnetic wave with a plurality of waves with high accuracy, and an electric steering device using the same.

[0009]

According to a first aspect of the present invention, there is provided a torque sensor which rotates the input shaft and the output shaft which are coaxially connected via a torsion bar, to thereby apply a torque applied to the input shaft and the output shaft to the torsion. In the torque sensor for detecting the torsion angle generated in the bar, the torque sensor is provided on the outer peripheral portion of the input shaft, and is provided on the outer peripheral portion of the output shaft along with first and second magnetic waves along the circumferential direction of the input shaft. A third magnetic wave along the circumferential direction of the output shaft, and a first magnetic wave fixed to face the first to third magnetic waves.
And a third magnetic sensor, wherein the positions of the first and second magnetic sensors or the positions of the first and second magnetic ripples are different in the direction of rotation, and the first and second magnetic sensors are different. The torque is determined based on respective detection values detected by the magnetic sensor and the third magnetic sensor, and the rotation angle of the input shaft is determined based on the respective detection values detected by the first and second magnetic sensors. Is characterized in that

According to the first aspect, the first and second magnetic sensors and the third magnetic sensor are provided near the first and second magnetic streaks provided along the circumferential direction of the input shaft. An electric output is obtained in accordance with the strength of the magnetic field generated in the above manner and the strength of the magnetic field generated in the vicinity of the third magnetic streak provided along the circumferential direction of the output shaft. When the input shaft rotates, the first and second magnetic ripples are changed according to the waveforms of the first and second magnetic ripples.
The distance between the first and second magnetic sensors and the first and second magnetic waves changes, and the magnitude of the electrical output of the first and second magnetic sensors changes according to the change in the distance.

On one cycle of the first and second magnetic waves,
Since two positions correspond to one electrical output of each magnetic sensor, two positions corresponding to the electrical output of the first magnetic sensor and the electrical output of the second magnetic sensor The rotation angle of the input shaft is determined by comparing the two positions corresponding to.

That is, since the rotation angle of the input shaft corresponds to the steering angle of the steered wheels, higher precision detection is required as compared with the rotation angle of the output shaft. If one, the magnetic sensor will detect two positions for one electrical output on one cycle,
Since it is not possible to determine which of the two positions is the detected electrical output only from the electrical output of the magnetic sensor, the first invention uses two magnetic ripples and two magnetic sensors, and The rotation angle of the input shaft is obtained based on the detection value detected by the control unit.

Further, the rotation angle of the output shaft is obtained by obtaining the position closest to the rotation angle of the input shaft from the two positions corresponding to the electrical output of the third magnetic sensor. Furthermore,
A torque corresponding to the difference between the rotation angles is obtained.

As described above, there are provided two magnetic waves provided on the input shaft, one magnetic wave provided on the output shaft, and three magnetic sensors fixed to face the magnetic waves. Since the torque sensor has a simple and simple structure that can determine the torque and the rotation angle, the cost can be reduced as compared with a conventional torque sensor including a coil and a ring made of a magnetic material.

[0015] The torque sensor according to the second invention is characterized in that the torque applied to the input shaft and the output shaft which are coaxially connected via a torsion bar is rotated by rotating the input shaft by a torsion angle generated in the torsion bar. In the torque sensor for detecting, the fourth and fifth magnetic waves provided on the outer periphery of the input shaft and the output shaft, respectively, along the circumferential direction of the input shaft and the output shaft, and the fourth and fifth magnetic waves. 4th and 5th fixed to face the waves, respectively
And two fourth magnetic sensors arranged at different positions in the direction of rotation, and based on the respective detection values detected by these fourth magnetic sensors, A rotation angle is obtained, and the torque is obtained based on each detection value detected by the fourth and fifth magnetic sensors.

According to the second invention, the fourth magnetic sensor and the fifth magnetic sensor detect a magnetic field generated near a fourth magnetic streak provided along the circumferential direction of the input shaft. An electrical output is obtained according to the strength and the strength of the magnetic field generated near the fifth magnetic streak provided along the circumferential direction of the output shaft. When the input shaft rotates, the distance between the fourth magnetic sensor and the fourth magnetic wave changes according to the waveform of the fourth magnetic wave, and the fourth magnetic wave changes according to the change in the distance.
The electrical output of the magnetic sensor changes.

In one cycle of the fourth magnetic wave, two positions correspond to one electric output. Therefore, two magnetic sensors are provided for one fourth magnetic wave, The two positions corresponding to the electrical output of one magnetic sensor and the two positions corresponding to the electrical output of the other magnetic sensor are compared, and the matching position is determined to determine the rotational angle of the input shaft. Ask.

Further, the rotation angle of the output shaft is obtained based on the electric output of the fifth magnetic sensor. Further, a torque corresponding to the angle difference between the rotation angles is obtained.

Thus, one magnetic wave provided on the input shaft, one magnetic wave provided on the output shaft, and two magnetic sensors fixed to face the magnetic wave on the input shaft. , Which is fixed to face the magnetic streak of the output shaft 1
Since this is a torque sensor having a simple structure that can determine the torque and the rotation angle by including two magnetic sensors, the cost can be reduced as compared with a conventional torque sensor including a coil and a ring made of a magnetic material. Also, one magnetic wave is provided on each of the input shaft and the output shaft, and two magnetic sensors are arranged at different positions in the direction of rotation of the input shaft with respect to the magnetic wave on the input shaft. As compared with the case where three magnetic waves are provided as in the first invention and three magnetic sensors corresponding to these magnetic waves are provided, the length of the input shaft in the axial direction can be shortened and the size can be reduced.

The torque sensor according to the third invention is characterized in that the magnetic wave forms a plurality of waves.

According to the third aspect of the present invention, the electric output of the magnetic sensor changes with a plurality of periods for each rotation of the input shaft and the output shaft. The number of peaks of such electrical output is counted, the rotation angle corresponding to each peak position is obtained, and the rotation angle within one cycle is obtained as described above.
By calculating the sum of the two, the rotation angles of the input shaft and the output shaft can be detected with high accuracy.

According to a fourth aspect of the present invention, there is provided an electric steering apparatus comprising: a torque sensor according to any one of claims 1 to 3;
A motor for steering assistance driven based on the detection result of the torque sensor, and a transmission mechanism for transmitting rotation of the motor to an output shaft or a steering mechanism connected to the output shaft. .

According to the fourth aspect, since the rotation angle of the input shaft can be obtained by the torque sensor, the conventional rotation angle sensor can be eliminated, and the cost can be reduced.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is a schematic diagram showing the configuration of Embodiment 1 of a torque sensor A. In the torque sensor A, for example, a torsion bar 2 is coaxially connected to a lower end of an input shaft 1 connected to a steered wheel 30 for steering, and a lower end of the torsion bar 2 is connected to a steering mechanism connected to wheels. The upper end of the output shaft 3 is connected coaxially, and the torque applied to the input shaft 1 by rotating the steering wheel 30 is detected by the twist angle generated in the torsion bar 2.

In FIG. 1, reference numeral 4 denotes a first cylindrical body made of a non-magnetic material externally fitted to the lower end of the input shaft 1, and 5 denotes a second cylindrical body made of a non-magnetic material externally fitted to the upper end of the output shaft 3. It is a cylindrical body.

FIG. 2 is a developed view showing the structure of the magnetic streak, and FIG.
FIG. 3 is a perspective view of a magnetic streak. A first magnetic wave 11 made of a magnetic material and having a plurality of cycles of sine waves per rotation is provided on the outer peripheral surface of one end in the axial length direction of the first cylindrical body 4 so as to protrude along the circumferential direction. The outer peripheral surface of the other end of the cylindrical body 4 in the axial length direction includes:
One rotation is the same period as the magnetic wave 11,
A second magnetic wave 12 made of a magnetic material and having a waveform delayed in a period is provided in a convex shape along the circumferential direction.

On the outer peripheral surface of the second cylindrical body 5, a third magnetic wave 13 made of a magnetic material and having the same cycle as the magnetic wave 11 per rotation and having a waveform delayed by 1/4 cycle is formed per rotation. Are provided in a convex shape along the circumferential direction.

A support such as a housing for supporting the input shaft 1 and the output shaft 3 includes the first to third magnetic waves 11,
First to third magnetic sensors 21, 22, and 23 are fixedly arranged at the same position in the circumferential direction so as to face 12 and 13, respectively.

The first to third magnetic sensors 21 and
2 and 23 each have a pair of magnetoresistive elements,
The two magnetoresistive elements provided in the first to third magnetic sensors 21, 22, 23 are respectively provided on the input shaft 1 and the output shaft 3 so as to face the corresponding magnetic ripples 11, 12, 13. The magnetic waves 11, 12, 13 are arranged side by side in the axial direction at a distance substantially equal to the amplitude of the magnetic waves 11, 12, 13.

Each of the magnetoresistive elements has a property that its electric resistance increases as the intensity of a magnetic field formed around the element increases. In the first to third magnetic sensors 21, 22, and 23, the lower one of the two magnetoresistive elements is the terminal side to which a constant voltage is applied, and the upper one is the upper one. A voltage dividing circuit is connected to the ground terminal side and connected in series with the intermediate node serving as an output node.

Then, the first to third magnetic sensors 21,
Each of the magnets 22 and 23 has a magnet on the opposite side of the detection surface of the magnetoresistive element.

The magnet forms a magnetic field in a state where the magnetic flux is concentrated on the first to third magnetic ripples 11, 12, and 13. The electric resistance of each magnetoresistive element is a magnitude corresponding to the strength of the magnetic field formed around it, and the electric resistance of the magnetoresistive element on the constant voltage side is smaller than that of the magnetoresistive element on the ground side. When the electric resistance value is smaller than the electric resistance value, the output voltage of the magnetic sensor becomes higher. Conversely, when the electric resistance value of the magnetoresistive element on the constant voltage side is larger than the electric resistance value of the magnetoresistive element on the ground side, The output voltage decreases.

Accordingly, with the rotation of the steered wheels 30, the output voltages V ₂₁ ,
V ₂₂ and V ₂₃ change periodically. Since the first magnetic sensor 21 outputs an output voltage V ₂₁ corresponding to the waveform of the first magnetic wave 11, the periodic change becomes a sine wave, and the output voltage V _{22 of} the second magnetic sensor 22 is changed. Is a periodic change in which the phase of the output voltage V ₂₁ of the first magnetic sensor 21 is delayed by １ ／ cycle. Further, the output voltage V ₂₃ of the third magnetic sensor 23 changes periodically in phase with a slight delay from the output voltage V _{22 of} the second magnetic sensor 22 due to the torsion of the torsion bar 2.

The first to third magnetic sensors 21 and 22 are provided at an input portion of a control device 7 using a microprocessor.
2, 23 and a vehicle speed sensor 8 for detecting the running speed of the vehicle
And a drive circuit 10 of a motor 9 of the electric steering device described later is connected to the output unit.

The control device 7 controls the output voltages V ₂₁ , V ₂₂ , V ₂₃ output by the first to third magnetic sensors ₂₁ , ₂₂ , _23.
Of the steering wheel 30 steered using the steering wheel 30 and the steering wheel 3
The torque T applied to 0 is obtained, and the drive of the motor 9 for assisting the steering of the steered wheels 30 is controlled. In the control device 7, for example, as described below, the steering angle θ and the torque T are determined at predetermined intervals from the output voltages V21, V22, V23 of the first to third magnetic sensors ₂₁ , ₂₂ , _23. Detect in chronological order.

When no torque is applied to the steered wheels 30 and the steered wheels 30 and the wheels are facing the front, a neutral state is set. At this time, the steering angle θ and the torque T are set to zero. I have.

First, detection of the steering angle θ will be described. Changes in the output voltages V ₂₁ and V ₂₂ of the first and second magnetic sensors 21 and 22 when the steered wheels 30 are rotated are expressed as Expressions (1) and (2). V ₂₁ = A ₂₁ · sin (n · θ ₁ ) + VO ₂₁ (1) V ₂₂ = A ₂₂ · cos (n · θ ₁ ) + VO ₂₂ (2) where A ₂₁ and A ₂₂ are the output voltages V, respectively. _21, the amplitude of the V _22, n
Rotation angle of the input shaft 1 of the periodic number per rotation of the first and second magnetic Namijo 11, theta ₁ is one period of the first and second magnetic Namijo 11 and 12, VO ₂₁ , VO ₂₂ is the first
And the bias voltages of the second magnetic sensors 21 and 22.

The output voltage V of the third magnetic sensor 23
The change of ₂₃ is expressed as equation (3). V ₂₃ = A ₂₃ · cos (n · θ ₃ ) + VO ₂₃ (3) where A ₂₃ is the amplitude of the output voltage V ₂₃ , and θ ₃ is the output shaft 3 of the third magnetic wave 13 during one period. Rotation angle, VO ₂₃ is 3rd
Of the magnetic sensor 23 of FIG.

The first to third magnetic sensors 21 and
22 and 23 have substantially the same output characteristics, and have amplitudes A ₂₁ ,
Since A ₂₂ and A ₂₃ and the bias voltages VO ₂₁ , VO ₂₂ and VO ₂₃ are respectively adjusted to have a predetermined amplitude A and a predetermined bias voltage VO, the equations (1) and (2) are used. ) And Equation (3) become Equations (4), (5) and (6), respectively. V ₂₁ = A · sin (n · θ ₁ ) + VO (4) V ₂₂ = A · cos (n · θ ₁ ) + VO (5) V ₂₃ = A · cos (n · θ ₃ ) + VO (6) )

Equations (4) and (5) are replaced by equations (7) and (8).
Deformed to obtain the rotation angle theta _1. θ ₁ = (1 / n) · arcsin (V ₂₁ −VO) / A｝ (7) θ ₁ = (1 / n) · arccos ｛(V ₂₂ −VO) / A｝ (8)

From equations (7) and (8), the angle θ ₁
Are obtained two by two, these are compared, and the corresponding angle is adopted as the rotation angle θ ₁ .

The equation (6) is transformed into the equation (9) to determine the rotation angle θ ₃ . θ ₃ = (1 / n) · arccos {(V ₂₃ −VO) / A} (9)

Two rotation angles θ ₃ can be obtained from Expression (9). However, since the torsion angle of the torsion bar 2 is at most several degrees, the obtained two angles and the previously obtained rotation angle θ ₁ are obtained. And _one that substantially matches the rotation angle θ ₁ is adopted as the rotation angle θ ₃ .

[0044] Further rotation direction of the steering wheel 30 described later is not more time in the positive direction, when the output voltage V ₂₂ exceeds a peak increments the counter C1 for rotation angle computation of the input shaft 1 side, the It effected even if the rotational direction is the negative direction, when the output voltage V ₂₂ exceeds a peak is adapted to decrement the counter C1. Similarly, when the rotation direction is the positive direction and the output voltage V
If _{the 23} exceeds a peak increments the counter C2 for the rotation angle computing the output shaft 3 side, the rotational direction is not more time in the negative direction, when the output voltage V ₂₃ exceeds the peak, the The counter C2 is decremented.

Then, the value of the counter C1 is 360 ° / n
Obtains the rotation angle theta _IN of the input shaft 1 by adjusting the theta ₁ to the result of multiplying the 360 ° of the value of the counter C2 / n
The rotation angle θ _OUT of the output shaft 3 is obtained by adding or subtracting θ ₃ to the result of multiplication. The rotation angle θ _IN of the input shaft 1 is defined as a steering angle θ.

Further, the control device 7 controls the time calculated as described above.
Roll angle θ₁And the previously obtained rotation angle θ ₁Compare with ´
Whether the rotation direction of the steered wheels 30 described above is a predetermined forward direction
Find the negative direction.

Next, detection of the torque T will be described.
The torsion angle Δθ of the torsion bar 2 is obtained from the equation (10). Δθ = θ _IN −θ _OUT … (10)

The torque T corresponding to the determined torsion angle Δθ is
It is determined from the relationship between the twist angle Δθ and the torque T given in advance.

Then, the drive circuit 10 is controlled according to the obtained torque T, the motor 9 is driven, and the required steering assist force is transmitted to the output shaft 3.

FIG. 4 is a sectional view of a portion of the electric steering device in which the torque sensor is incorporated. The torque sensor configured as described above is used, for example, in an electric steering device. In this electric steering device, the upper end of the steering wheel 30 is steered through a steering shaft 31.
And the output shaft 3 whose lower end is connected to a steering mechanism via a transmission shaft having a pinion.
And a lower end of the input shaft 1 is coaxially inserted into an upper end of the output shaft 3 so as to be relatively rotatable.
The torsion bar 2 is inserted into a hole of the output shaft 3.

The upper end of the torsion bar 2 and the upper end of the input shaft 1 are connected by a dowel pin 32, and the lower end of the torsion bar 2 and the lower end of the output shaft 3 are connected by a dowel pin 33. A housing 6 for rotatably supporting the output shaft 3 and the output shaft 3
Between the first and third magnetic sensors 2
A transmission mechanism 34 having a worm interlocked with a steering assist motor 9 controlled based on the detection results of 1, 2, 23 and a worm wheel meshing with the worm is provided. The third to third magnetic sensors 21, 22, 23 are fixed.

In this electric steering apparatus, the steered wheels 30
Is rotated left or right from the steering angle midpoint, the input shaft 1 rotates and the output shaft 3 rotates, and the magnetic field generated in the vicinity of the first to third magnetic waves 11, 12, and 13 Are individually detected by the first to third magnetic sensors 21, 22, and 23, and the output voltages output from the magnetic sensors 21, 22, and 23 are time-sequentially transmitted to the control device 7 as the intensity of the magnetic field. Taken in.

First and second magnetic sensors 2 taken in
The rotation direction of the input shaft 1, the rotation angle θ _{IN with} respect to the steering angle midpoint of the input shaft 1 and the steering angle θ of the steered wheels 30 are obtained from the output voltages V ₂₁ and V _{22 of the} first and second motors. rotation angle theta _OUT for steering angle midpoint of the output shaft 3 from the output voltage V ₂₃ of the sensor 23 are determined, these rotation angles theta _iN, theta _OUT
Is determined in accordance with the angle difference Δθ of the motor 9, a signal corresponding to the torque T is output to the drive circuit 10, and the motor 9
Rotates clockwise or counterclockwise, forcibly rotates the output shaft 3 via the transmission mechanism 34, and assists steering.

As described above, the torque sensor A for detecting the torque applied to the input shaft 1 includes two magnetic waves 11 and 12 provided on the outer periphery of the input shaft 1 and one magnetic wave 11 and 12 provided on the outer periphery of the output shaft 3. The magnetic waves 13 and these magnetic waves 11, 1
Since it is a torque sensor having a simple and simple structure that includes three magnetic sensors 21, 22, and 23 fixed to face each other, the torque, the rotation angle and the rotation direction can be obtained. The cost of the torque sensor can be reduced as compared with a conventional torque sensor having a magnetic ring.

Further, since the steering angle θ can be obtained by the torque sensor, it is not necessary to use a rotation angle sensor separate from the torque sensor, and the cost of the electric steering device can be reduced.

In the first embodiment described above, the first
The first and third magnetic sensors 21 and 21 have a sinusoidal waveform, the second and third magnetic ripples 12 and 13 have waveforms that are delayed by ４ cycle of the first magnetic ripple 11. , 22,2
3 is the same in the circumferential direction, but the first to third magnetic waves 11, 12, and 13 have waveforms of different phases, respectively, and the positions of the first to third magnetic sensors 21, 22, and 23 are circumferential. The directions may be the same or different, and the first to third magnetic waves 11, 12, and 13 may have the same phase waveform, respectively, and the first to third magnetic sensors 21, 22, 23 The positions may be different in the circumferential direction.

Embodiment 2 FIG. 5 is a schematic view showing the structure of a torque sensor A according to Embodiment 2, FIG. 6 is a developed view showing the structure of a magnetic streak, and FIG. 7 is the fourth and fifth magnetic sensors. It is explanatory drawing which shows the positional relationship with a magnetic streak.

In the second embodiment, the first
The input shaft 1 and the output shaft 3 are made of a nonmagnetic material, respectively, instead of providing the two magnetic waves 11 and 12 on
And the fourth cylinders 16 and 17 are externally fitted and fixed.
Fourth and fifth magnetic waves 14, 14 made of a magnetic material and having a plurality of cycles of a sine wave or a cosine wave per rotation,
15 are provided in a convex shape along the circumferential direction. The positions of the fourth and fifth magnetic waves 14 and 15 in the rotational direction of the input shaft 1 may be different from each other in addition to the same position.

Two fourth magnetic sensors 24, 24a and two fifth magnetic sensors 25, 24, 24
25a is fixedly provided. Further, the fourth magnetic sensor 2
4, 24a move the magnetic wave 1 in the direction of rotation of the input shaft 1.
Each of the fifth magnetic sensors 25 and 25a is arranged at a position different from the output shaft 3 by a quarter of the fourth axis.
Are arranged at positions different from each other by 1/4 period of the magnetic streaks 15 in the rotation direction.

The fourth and fifth magnetic sensors 24, 24a,
25, 25a are first to third magnetic sensors 21,
Like the reference numerals 2 and 23, each has a pair of magnetoresistive elements, and is arranged, for example, vertically above and below both ends in the width direction of the corresponding magnetic stripes 14 and 15, respectively.
Further, it has a property that its electric resistance value increases as the strength of the magnetic field formed around each magnetoresistive element wave increases. Further, the fourth and fifth magnetic sensors 2
4, 24a, 25, and 25a, like the first to third magnetic sensors 21, 22, and 23, have a voltage dividing circuit formed by the magnetoresistive effect element.
Magnets are arranged at the center on the back side of the voltage dividing circuits 4, 24a, 25 and 25a.

Such magnetic sensors 24, 24a, 2
The output voltages V ₂₄ , V _24a , V ₂₅ , V _25a of 5, _25a are
With the rotation of the steered wheels 30, each of the corresponding magnetic waves 1
It changes periodically according to the waveforms 4 and 15. Among the fourth magnetic sensors 24, 24a, the output voltage V ₂₄ of the ₂₄ has a sinusoidal periodic change, and the output voltage V _24a of the _24a is a cycle obtained by changing the phase of the output voltage V ₂₄ by １ ／ cycle. Make a significant change. Further, of the fifth magnetic sensors 25 and 25a, 2
5 of the output voltage V ₂₅ is no periodic change slightly delayed phase than the output voltage V ₂₄ by torsion of the torsion bar 2, 25a is the output voltage V _25a 1/4 the phase of the output voltage V ₂₅ Make periodic changes with different periods.

The input section of the control device 7 using a microprocessor is provided with the fourth and fifth magnetic sensors 24 and 2.
4a, 25, 25a and a vehicle speed sensor 8 for detecting the traveling speed of the vehicle are connected, and a drive circuit 10 for a motor 9 of the electric steering device is connected to an output unit.

The control unit 7 controls the output voltage V ₂₄ output by the fourth and fifth magnetic sensors 24, 24a, 25, 25a,
For example, a steering angle θ and a torque T are obtained from V _24a , V ₂₅ , and V _25a by the principle described below, and the motor 9 for assisting the steering of the steered wheels 30 is drive-controlled.

Changes in the output voltages V ₂₄ and V _24a of the fourth magnetic sensors 24 and 24a when the steered wheels 30 are rotated are as follows.
It is expressed as Expression (11) and Expression (12). V ₂₄ = A ₂₄ · sin (m · θ ₄ ) + VO ₂₄ (11) V _24a = A _24a · cos (m · θ ₄ ) + VO _24a (12) where A ₂₄ and A _24a are output voltages V, respectively. ₂₄ , V _24a amplitude, m is the number of periods per rotation of the fourth magnetic wave 14,
₄ is the rotation angle of the input shaft 1 during one period of the fourth magnetic wave 14, and VO ₂₄ and VO _24a are the fourth magnetic sensors 24 and 2, respectively.
4a is the bias voltage.

Similarly, the changes of the output voltages V ₂₅ and V _25a of the fifth magnetic sensors 25 and 25a are calculated by the equations (13) and (1).
4). V ₂₅ = A ₂₅ · sin (m · θ ₅ ) + VO ₂₅ (13) V _25a = A _25a · cos (m · θ ₅ ) + VO _25a (14) where A ₂₅ and A _25a are output voltages V, respectively. ₂₅ , V _25a , m is the number of periods per rotation of the fifth magnetic wave 15,
₅ is the rotation angle of the output shaft 3 during one period of the fifth magnetic wave 15, and VO ₂₅ and VO _25a are the fifth magnetic sensors _{25 and 2} , respectively.
5a is the bias voltage.

The fourth and fifth magnetic sensors 24, 24a,
The output characteristics of 25 and 25a are substantially the same. Therefore, the amplitudes A ₂₄ , A _24a , A ₂₅ , and A _25a are approximated to a predetermined value A,
By approximating the bias voltages VO ₂₁ , VO ₂₂ , and VO ₂₃ to a predetermined value VO, Expressions (11), (12), (13), and (14) are replaced by Expressions (15) and (14), respectively. 1
6), Equation (17), and Equation (18). V ₂₄ = A · sin (m · θ ₄ ) + VO (15) V _24a = A · cos (m · θ ₄ ) + VO (16) V ₂₅ = A · sin (m · θ ₅ ) + VO (17) ) V _25a = A · cos (m · θ ₅ ) + VO (18)

Equations (15) and (16) are transformed into equations (19) and (20) to determine the rotation angle θ ₄ . θ ₄ = (1 / m) · arcsin ｛(V ₂₄ −VO) / A｝ (19) θ ₄ = (1 / m) · arccos ｛(V _24a −VO) / A｝ (20)

From the equations (19) and (20), two angles θ ₄ are obtained, respectively, and these are compared and the coincident angle is adopted as the rotation angle θ ₄ .

Similarly, equations (17) and (18) are replaced by equation (2)
1), it is deformed into the equation (22) obtains the rotational angle theta _5. θ ₅ = (1 / m) · arcsin ｛(V ₂₅ −VO) / A… (21) θ ₅ = (1 / m) · arccos ｛(V _25a −VO) / A｝ (22)

From the equations (21) and (22), two angles θ ₅ are respectively obtained. These are compared, and the coincident angle is adopted as the rotation angle θ ₅ .

The control device 7 compares the rotation angle θ ₄ with the previously obtained rotation angle θ ₄ ′ to determine the rotation direction of the steered wheels 30. Further, when rotating in the forward direction, the output voltage V _24a
The counter C4 is incremented when the output voltage _V24a reaches a peak during the rotation in the negative direction, and the counter C4 is decremented when the output voltage _V24a reaches a peak during the rotation in the negative direction. Similarly, during the rotation in the positive direction, the output voltage V _25a
When the output voltage V _25a reaches a peak during the rotation in the negative direction, the counter C5 is decremented.

Then, the value of the counter C4 is set to 360 ° / m
The rotation angle θ _IN of the input shaft 1 is obtained by adding or subtracting θ ₄ to the result of multiplying the result of the multiplication by
The rotation angle θ _OUT of the output shaft 3 is obtained by adding or subtracting θ ₅ to the result of multiplying by. The rotation angle θ _IN of the input shaft 1 is defined as a steering angle θ.

Further, similarly to the first embodiment, the torsion angle Δθ of the torsion bar 2 is obtained from the equation (10).

The torque T corresponding to the obtained twist angle Δθ is
It is determined from the relationship between the twist angle Δθ and the torque T given in advance.

The torque sensor according to the second embodiment is used for an electric steering device, for example, as in the first embodiment. still,
The structure of the torque sensor built-in portion of the electric steering device is the same as that of FIG.

In the second embodiment, when the steered wheel 30 is rotated left or right from the midpoint of the steering angle, the input shaft 1 rotates and the output shaft 3 rotates, and the fourth to fifth rotations are performed. Fourth and fifth magnetic sensors 24, 24a, 25, 25a individually detect the strength of the magnetic field generated in the vicinity of the magnetic waves 14, 15, and these magnetic sensors 24, 24a, 2
The output voltages output from the control devices 5 and 25a are chronologically taken into the control device 7 as the strength of the magnetic field.

The captured fourth magnetic sensors 24, 24a
Output voltage V_{twenty four}, V_24aInput shaft 1 rotation direction, input
Rotation angle θ with respect to the steering angle midpoint of shaft 1_INAnd the steering wheel 30
The steering angle θ is obtained, and the fifth magnetic sensor 25, 2
Output voltage V of 5a_{twenty five}, V_25aTo the middle point of the steering angle of the output shaft 3
Rotation angle θ_OUTAre required, these rotation angles
θ _IN, Θ_OUTThe torque T according to the angle difference △ θ
And a signal corresponding to the torque T is output to the drive circuit 10.
Then, the motor 9 rotates clockwise or counterclockwise, causing the transmission mechanism 33 to rotate.
The output shaft 3 is forcibly rotated through the shaft to assist steering.

As described above, the torque sensor A for detecting the torque applied to the input shaft 1 includes one magnetic wave 14 provided on the input shaft 1, one magnetic wave 15 provided on the output shaft 3, Two magnetic sensors 24, 24a fixed to face the magnetic wave 14, and a magnetic wave 15 of the output shaft 3;
Magnetic sensors 25, 2 fixed to face each other
5a, and is a simple and simple structure torque sensor that can determine torque, rotation angle, and rotation direction. Therefore, the cost of the torque sensor is lower than that of a conventional torque sensor having a coil and a ring made of a magnetic material. Can be reduced. Moreover, since the steering angle θ can be obtained by the torque sensor, it is not necessary to use a rotation angle sensor separate from the torque sensor, and the cost of the electric steering device can be reduced.

In the second embodiment described above, the fourth
And five fifth magnetic sensors 24, 24a, 25, 25a, respectively.
Let a be two and the fifth magnetic sensor 25 be one, and from the output voltages V ₂₄ and V _{24a of} the fourth magnetic sensors 24 and 24a among the two rotation angles θ ₅ obtained from the equation (21). One that substantially matches the obtained rotation angle θ ₄ may be adopted as the rotation angle θ ₅ , and the rotation angle θ _OUT of the output shaft 3 may be obtained.

In the second embodiment, since other structures and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and the detailed description of the structure and the operation will be omitted.

In Embodiments 1 and 2, the magnetic ripple 11
15 to 15 may be configured to form a single wave in addition to the configuration that forms a plurality of waves. In addition, the cylinders 4, 5, 16, 1 made of a nonmagnetic material
7 is provided with the convex magnetic waves 11 to 15 made of a magnetic material. However, the magnetic materials 11, 5, 16 and 17 are provided with the convex or grooved magnetic waves 11 to 15. In addition, flush or grooved magnetic waves 11 to 11 are formed on the cylindrical bodies 4, 5, 16 and 17 made of a non-magnetic material.
15 may be provided.

In the first and second embodiments, the magnetic waves 11 to 15 are provided on the cylinders 4, 5, 16, 17 provided separately from the input shaft 1 and the output shaft 3. , 5,1
6, 17 are fixed externally to the input shaft 1 and the output shaft 3. Alternatively, the magnetic waves 11 to 15 may be provided directly to the input shaft 1 and the output shaft 3, for example.

In the first and second embodiments, the magnetic sensors 21 to 25a are provided with magnets, and the magnets are used to form magnetic fields in the vicinity of the magnetic waves 11 to 15 made of magnetic material. The magnetic fields may be formed in the vicinity of these by using the strips 11 to 15 as magnets. A pair of magnetoresistive elements provided in each of the magnetic sensors 21 to 25a includes a magnetic wave 11 in the axial length direction of the input shaft 1 and the output shaft 3.
In addition to arranging them at a distance equivalent to the amplitude of ~ 15,
For example, the magnetic waves may be arranged side by side in the axial direction so as to face the central portion in the axial direction.

Each of the magnetic sensors 21 to 25a may be provided with, for example, a Hall element in addition to the magnetic sensor.

The torque sensor according to the present invention may be used not only for an electric steering device but also for devices other than the electric steering device.

[0086]

According to the first aspect of the present invention, there are provided three magnetic waves provided on the input shaft and the output shaft and three magnetic sensors corresponding thereto, and a simple and simple structure capable of obtaining the torque and the rotation angle. Therefore, the cost can be reduced as compared with a conventional torque sensor including a coil and a ring made of a magnetic material.

According to the second aspect of the present invention, there is provided a torque sensor having a simple and simple structure including two magnetic streaks provided on the input shaft and the output shaft and at least three magnetic sensors, and capable of determining a torque and a rotation angle. Therefore, the cost can be reduced as compared with a conventional torque sensor having a coil and a ring made of a magnetic material.

According to the third aspect, one of the input shaft and the output shaft is
In response to the rotation, the electrical output of the magnetic sensor changes in a plurality of cycles, counts the number of peaks of such electrical output, and determines the rotation angle of the input shaft and output shaft corresponding to each peak position. , And the sum of this and the rotation angle during one cycle of the electrical output is obtained, whereby the rotation angles and torque of the input shaft and the output shaft can be detected with high accuracy.

According to the fourth aspect, since the rotation angle of the input shaft can be obtained by the torque sensor, the conventional rotation angle sensor can be eliminated, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a first embodiment of a torque sensor according to the present invention.

FIG. 2 is a development view showing a configuration of a magnetic streak of the torque sensor according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a magnetic wave of the torque sensor according to the present invention.

FIG. 4 is a cross-sectional view of a part where the torque sensor is incorporated in the electric steering device according to the present invention.

FIG. 5 is a schematic diagram illustrating a configuration of a torque sensor according to a second embodiment of the present invention.

FIG. 6 is a developed view showing a configuration of a magnetic wave of a torque sensor according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a positional relationship between fourth and fifth magnetic sensors and magnetic streaks.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 input shaft 2 torsion bar 3 output shaft 11 first magnetic wave 12 second magnetic wave 13 third magnetic wave 14 fourth magnetic wave 15 fifth magnetic wave 21 first magnetic sensor 22 second magnetic sensor 23 third magnetic sensor 24, 24a fourth magnetic sensor 25, 25a fifth magnetic sensor

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2F051 AA01 AB05 AC01 BA03 2F063 AA34 BA08 BB05 BC10 BD16 CA34 DA01 DA04 DA08 DB01 DC03 DD01 EA20 GA01 KA01 KA04 KA06 LA02 NA06 ZA01 3D033 CA03 CA13 CA16 CA17 CA21 CA28 CA29

Claims (4)

[Claims] A torque sensor for detecting a torque applied to the input shaft and the output shaft coaxially connected to each other through a torsion bar by rotating the input shaft by a torsion angle generated in the torsion bar; First and second magnetic waves provided on the outer periphery of the input shaft along the circumferential direction of the input shaft; and third magnetic waves provided on the outer circumferential portion of the output shaft along the circumferential direction of the output shaft. And a first to third magnetic sensor fixed to face the first to third magnetic waves, respectively, and the positions of the first and second magnetic sensors or the first and third magnetic sensors. The position of the second magnetic wave is different in the direction of rotation, and the first and second magnetic waves are different.
The torque is obtained based on the respective detection values detected by the magnetic sensor and the third magnetic sensor, and the rotation of the input shaft is determined based on the respective detection values detected by the first and second magnetic sensors. A torque sensor characterized in that an angle is obtained. 2. A torque sensor for detecting a torque applied to the input shaft and an output shaft connected to each other coaxially through a torsion bar by rotating the input shaft by a torsion angle generated in the torsion bar. Provided on the outer periphery of the input shaft and the output shaft, respectively, so as to face the fourth and fifth magnetic waves along the circumferential direction of the input shaft and the output shaft, and to face the fourth and fifth magnetic waves, respectively. Fourth and fifth magnetic sensors to be fixed,
The two magnetic sensors are arranged at different positions in the direction of rotation, and the rotation angle of the input shaft is obtained based on the respective detection values detected by the fourth magnetic sensor. A torque sensor, wherein the torque is obtained based on respective detection values detected by a fifth magnetic sensor. 3. The torque sensor according to claim 1, wherein the magnetic wave forms a plurality of waves. 4. A torque sensor according to claim 1, a steering assist motor driven based on a detection result of the torque sensor, and an output shaft or A transmission mechanism for transmitting a signal to a steering mechanism connected to the output shaft.