JP2001091376A - Torque sensor and electrically-driven steering device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor capable of detecting a steering angel and torque and an electrically-driven steering device using the same. SOLUTION: A first circular magnet plate 51 in which a plurality of notches 51S, 51S, 51S... are provided in its circumference is mounted to an input shaft 1, and a second magnetic plate 52 in a similar shape to the first magnetic plate 51 is mounted to an output shaft 2. The intensities of magnetic fields formed by the two magnets arranged in the vicinity of magnetic sensors MG1 and MG2 are detected by the magnetic sensors MG1 and MG2 arranged on the upper side of the first magnet plate 51. A steering angle and torque are detected on the basis of the output results of the magnetic sensors MG1 and MG2.

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 steering torque applied to a steered wheel, and an electric steering device for driving an electric motor based on a detection result of the torque sensor to generate a steering assist force. .

[0002]

2. Description of the Related Art FIG. 20 is a longitudinal sectional view showing the structure of a conventional electric steering device. In the figure, reference numeral 104 denotes a cylindrical input shaft, and an upper end of the input shaft 104 is connected to a steering wheel (not shown) via an upper shaft. The lower end of the upper shaft is connected to an upper end of a connecting shaft 105 inserted inside the input shaft 104, and the lower end of the connecting shaft 105 is connected to a cylindrical output shaft 107. The upper end of the output shaft 107 is inserted into the lower end of the input shaft 104, and the upper shaft, the input shaft, and the output shaft 107 are supported in the housing 111 via bearings.

In the housing 111, a connecting shaft 10 is provided.
Sensor 1 for detecting a steering torque based on the relative displacement of an input shaft 104 and an output shaft 107 connected via
12 and a speed reduction mechanism 114 for reducing the rotation of a steering assist electric motor 113 driven based on the detection result of the torque sensor 112 and transmitting the rotation to the output shaft 107, according to the rotation of the steering wheel. The operation of the steering mechanism is assisted by the rotation of the electric motor 113 to reduce the labor burden on the driver for steering. The lower end of the output shaft 107 is connected to a rack and pinion type steering mechanism via a universal joint.

As the torque sensor 112, for example, a sensor disclosed in Japanese Patent Publication No. 07-021433 is used. In the torque sensor 112, magnetic rings 112a and 112b fixed to the input shaft 104 and the output shaft 107, respectively, are provided inside a torque detecting coil 112c fixed in the housing 111 around the connection shaft 105. Are located. Magnetic ring 1
A plurality of rectangular teeth are formed over the entire periphery at the same pitch on opposing end surfaces of 12a and 112b, and a ring made of a magnetic material on the side of the input shaft 104 corresponding to the torsion of the connection shaft 105 is provided. 112a and the magnetic ring 1 on the output shaft 107 side
When the tooth 12b rotates relative to the tooth 12b, the facing area of the tooth portion changes, and the impedance of the torque detection coil 112c changes. A non-contact sensor that detects the steering torque based on the change in the impedance is used.

[0005]

In the conventional electric steering apparatus as described above, it is difficult to reduce the size of the torque sensor 112 because the torque sensor 112 has the torque detection coil 112c. Since a large installation space is required, it is difficult to reduce the size of the electric steering device.

Further, in the conventional electric steering device as described above, the torque sensor cannot detect the steering angle which is one of the state variables used for controlling the driving of the motor of the electric steering device. Therefore, the conventional electric steering device requires a dedicated device for detecting the steering angle, which causes an increase in cost and installation space.

The present invention has been made in view of the above circumstances, and has a magnetic structure having two disk-shaped magnetic members provided with notches and an element for obtaining an electrical output corresponding to the strength of a magnetic field. By using the sensor, the torque sensor is shorter in the axial direction of the input shaft and the output shaft, is smaller than the conventional one, can detect the torque and the steering angle, and does not require a dedicated device for detecting the steering angle. And an electric steering device using the same.

[0008]

According to a first aspect of the present invention, there is provided a torque sensor for detecting a torque applied to an input shaft by a torsion angle generated in a connecting shaft connecting the input shaft and the output shaft. Are provided, and the first and second magnetic bodies are attached to the input shaft and the output shaft so as to face each other, each having an opposing portion, and near the first and second magnetic bodies. A magnetic sensor for obtaining an electrical output in accordance with the strength of the magnetic field, wherein the torque is obtained from the strength of the magnetic field detected by the magnetic sensor.

A torque sensor according to a second aspect of the present invention is the torque sensor according to the first aspect, wherein a magnet is arranged near the first and second magnetic bodies.

[0010] A torque sensor according to a third invention is characterized in that, in the torque sensor according to the first invention, the first and second magnetic bodies are respectively magnetized.

A torque sensor according to a fourth aspect of the present invention is the torque sensor according to any one of the first to third aspects, wherein when one magnetic sensor is located at a position facing one notch, the other magnetic sensor is not. Each magnetic sensor is arranged so as to be located at a position facing an intermediate portion between two adjacent notches.

A torque sensor according to a fifth aspect of the present invention is the torque sensor according to any one of the first to fourth aspects, wherein the first and second magnetic bodies have a disk shape, and the notch is It is characterized in that the first and second magnetic bodies are arranged radially equally.

A torque sensor according to a sixth aspect of the present invention is the torque sensor according to any one of the first to third aspects, wherein the first and second magnetic bodies are disc-shaped, and the notch is The notch of the first magnetic body and the notch of the second magnetic body are provided so as to intersect with each other.
And the second magnetic body is equally arranged in the circumferential direction.

A torque sensor according to a seventh aspect of the present invention is the torque sensor according to any one of the first to fourth aspects, wherein the first and second magnetic bodies have a cylindrical shape, and the notch has an input shaft. The first and second magnetic members are equally arranged in the circumferential direction of the first and second magnetic members.

According to an eighth aspect of the present invention, in the torque sensor according to any one of the first to third aspects, the first and second magnetic bodies are cylindrical, and the notch is The notch of the first magnetic body and the notch of the second magnetic body cross each other, and are arranged equally in the circumferential direction of the first and second magnetic bodies. And

According to a ninth aspect of the present invention, there is provided an electric steering device based on the torque sensor according to any one of the first to eighth aspects mounted on an input shaft and an output shaft, and a torque detected by the torque sensor. It is characterized by comprising a drive assisted electric motor mounted on the output shaft or a steering mechanism connected to the output shaft for steering assistance.

In the case of the torque sensor according to the first or second invention, a magnet is provided near the first and second magnetic bodies to generate a magnetic field. When a torque is applied to the input shaft in this state, a change in the relative angle occurs between the input shaft and the output shaft, thereby changing the facing areas of the notches provided in the first and second magnetic bodies, respectively. I do.

FIG. 1 is a plan view of the first and second magnetic bodies, and FIG. 2 is a sectional view taken along the line II-II of FIG.
It is explanatory drawing which shows the change of the magnetic field around 1st and 2nd magnetic body accompanying the change of the opposing area of a notch. In the figure,
Reference numeral 510 denotes a first magnetic body having a disk shape, and 520 denotes a second magnetic body. First and second magnetic bodies 510, 52
When a magnetic field is formed around 0, since the magnetic material portion has a higher magnetic permeability than the notch (air), the magnetic flux density near the magnetic material is high, and the magnetic flux density near the notch is low. A magnetic field is formed. Therefore, the first and second magnetic members 5
When the facing areas of the notches 10 and 520 are large, as shown in FIG. 2A, the magnetic flux concentrates on the portion where the magnetic bodies face each other, and the magnetic flux concentrates on the portion where the notches face each other. The magnetic flux density becomes extremely small. On the other hand, when the facing area of the notch is small, as shown in FIG.
The magnetic flux is distributed substantially uniformly throughout the first and second magnetic bodies 510 and 520. The magnetic flux density at this time is lower than the magnetic flux density of the portion where the magnetic bodies oppose each other when the opposing area of the notch is large, and is higher than the magnetic flux density of the portion where the notches oppose each other.

When the steering angle of the input shaft changes, the first magnetic body fixed to the input shaft rotates.
At this time, in the vicinity of the magnetic sensor fixed in the vicinity of the first magnetic body, the portion of the magnetic body and the cutout portion alternately pass. Here, the strength of the magnetic field is strong near the portion of the magnetic body, and the strength of the magnetic field is weak near the portion of the notch. Therefore, the strength of the magnetic field detected by the magnetic sensor periodically changes with the rotation. Changes to

This periodic change is caused by the reason described above.
The larger the opposing area of the notch, the greater the difference in the density of the magnetic flux density, so the amplitude increases. The smaller the area of the notch, the smaller the difference in the density of the magnetic flux, the smaller the amplitude. Therefore, the change in the amplitude of the periodic change corresponds to the change in the torque, and the number of the periodic changes corresponds to the steering angle on the input shaft side.

Therefore, the torque can be detected by determining the amplitude of the periodic change in the output voltage of the magnetic sensor and determining the torque corresponding to the amplitude from the relationship between the amplitude and the torque that is given in advance. Becomes

The steering angle can be detected by counting the peak of the periodic change.

In the case of the torque sensor according to the third invention, the torque sensor according to the second invention forms a magnetic field by magnets arranged near the first and second magnetic bodies, whereas the torque sensor according to the second invention has the first and second torque sensors. A magnetic field is formed by the magnetic substance itself. As a result, the magnetic field near the magnetic sensor changes with the change in the rotation angle of the first and second magnetic bodies.
By detecting this, the torque and the steering angle can be detected.

In the case of the torque sensor according to the fourth aspect of the present invention, the steering angle can be detected with a resolution equal to or greater than the pitch of the notch according to the principle described below. In order to accurately control the electric steering device, it is necessary to detect an accurate steering angle. Between the peaks of the change of the output voltage of the magnetic sensor, two steering angles exist for one output voltage value. Therefore, the phases of the periodic changes of the output voltages of the two magnetic sensors are made different, and one angle common to the respective magnetic sensors is obtained from a plurality of angles corresponding to the output voltages of the magnetic sensors.

FIG. 3 shows the electrical outputs of the two magnetic sensors and
It is a graph which shows the relationship with a steering angle. In the figure, the vertical axis
Is the electrical output value, and the horizontal axis is the angle. Also,
O₁, O _TwoIs attached near the first and second magnetic bodies.
Shows the waveform of the electrical output of each of the two magnetic sensors
ing. Waveform O of each electrical output₁, O_TwoOut of phase
One magnetic sensor faces one notch to smooth out
The other magnetic sensor is
Two magnetic sensors so that they are located opposite the part
Are arranged respectively.

Output waveform O₁Magnetic sensor has electrical output V
₁And output waveform O_TwoMagnetic sensor has electrical output V
_TwoOutput, the electrical output V₁Angle corresponding to
And within one cycle θ₁And θ_TwoThere are two angles
I do. Similarly, the electrical output V _TwoAs the angle corresponding to
Is θ within one cycle_TwoAnd θ_ThreeThere are two.
Two electrical outputs V₁, V_TwoΘ_TwoCorresponding
The steering angle at that time is the angle θ_TwoIdentified as
it can.

In the case of the torque sensor according to the fifth and seventh aspects of the present invention, the notches are equally arranged in the circumferential direction of the first and second magnetic members. The periodic change in the magnetic field strength of the second magnetic body has a sine wave shape. Therefore, it is possible to calculate the torque and the steering angle by a simple calculation.

In the case of the torque sensors according to the sixth and eighth aspects, when a torque is applied to the input shaft, the notch of the first magnetic body and the notch of the second magnetic body overlap each other. The resulting void moves as described below.
4 and 5 are explanatory diagrams showing the moving direction of the gap. In the figure, 510S and 520S are notches provided in the first and second disk-shaped magnetic bodies, respectively. For example,
The notch 510S has a shape extending in a direction inclined by 45 ° with respect to the radial direction of the first and second magnetic bodies, and the notch 520S has a shape extending in a direction inclined by 45 ° with respect to this. The cutouts 510S and 520S are arranged so as to cross each other. As shown in FIG. 4, when only the first magnetic body rotates about the point O, the gap formed by the intersection of the notches 510S and 520S is different from the position E _{0 in the} radial direction and the circumferential direction.
Move to ₁ . This is because the notches 510S and 520S intersect at different points before and after the movement.
Further, as shown in FIG. 5, the first and second magnetic bodies
When rotated together in the same direction about the said gap portion is moved from the position E ₀ to a different position E ₂ in the circumferential direction. This is because the notches 510S and 520S rotate while intersecting at the same point.

As described above, the magnetic material portion has a higher magnetic permeability than the air gap (air), so that the magnetic flux density near the magnetic material is increased around the first and second magnetic materials. A magnetic field having a high magnetic flux density near the gap and a low magnetic flux density is formed. Therefore, a plurality of magnetic sensors are arranged so that a plurality of magnetic sensors are always arranged around the gap. For this reason, the radial position and the circumferential position of the gap are specified by the output voltage value of the magnetic sensor around the gap, and the radial and circumferential movements from the predetermined neutral position, respectively, are specified. The steering angle can be obtained from the amount of movement of the gap in the circumferential direction, and the torque can be obtained from the relationship between the predetermined amount of movement of the gap in the radial direction and the torque.

Also, in the case of the torque sensor according to the fifth and sixth aspects, the first and second magnetic bodies having a disk shape,
Since it is made of a small component such as a magnetic sensor having a small magnetic detecting element, the size can be reduced as compared with the related art, and the installation space can be reduced.

In the case of the torque sensor according to the seventh and eighth inventions, the first and second cylindrical magnetic bodies,
Since it is made of a small component such as a magnetic sensor having a small magnetic detecting element, the size can be reduced as compared with the related art, and the installation space can be reduced.

In the case of the electric steering device according to the ninth invention, since the torque sensor according to any one of the first to eighth inventions is used, the steering angle is not provided with a dedicated device for detecting the steering angle. Can be detected.

Further, the provision of the torque sensor using the small magnetic detecting element makes it possible to reduce the size of the device as compared with the related art.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 The present invention will be described below in detail with reference to the drawings showing an embodiment. FIG. 6 shows a first embodiment of the torque sensor according to the present invention.
FIG. 7 is a front view showing a configuration of a main part of FIG. 7, and FIG. 7 is a schematic view showing a configuration of a main part of an electric steering device using the torque sensor.

In the drawing, reference numeral 1 denotes a cylindrical input shaft which is connected at an upper end thereof to a steering wheel via an upper shaft so as to be integrally rotatable. The upper end of the input shaft 1 and the upper end of a connecting shaft (torsion bar) 3 inserted inside the input shaft 1 are connected to the lower end of the upper shaft. Are connected to each other, and the input shaft 1 and the output shaft 2 are rotatably supported in a housing 4 via bearings 10 and 20, respectively.

In the housing 4, a torque sensor 5 according to the present invention for detecting a steering torque based on a relative displacement of the input shaft 1 and the output shaft 2 connected via the connection shaft 3 is provided.
Is installed. The detection result of the torque sensor 5 is output to the control unit 53 of the electric motor M, and the control unit 53 controls the drive circuit 54 of the electric motor M to drive the electric motor M, and the driving force is reduced by the deceleration mechanism. Through the output shaft 2. The lower end of the output shaft 2 is connected to a rack and pinion type steering mechanism via a universal joint.

FIG. 8 is a perspective view showing a configuration of a main part of the first embodiment of the torque sensor according to the present invention. A first disk-shaped hollow disk is formed near the connection between the input shaft 1 and the output shaft 2.
A second magnetic plate 52 having the same shape as the first magnetic plate 51 is fitted to the upper end of the output shaft 2 in a state facing the first magnetic plate 51. It is fixed. The first and second magnetic plates 51, 52 are provided with a number of notches 51S, 52S, each of which has a part of an annular shape, radially equally distributed in the circumferential direction.
52S is approximately the same size as the portion of the magnetic body between two adjacent notches. The notch 51
The shape of S, 52S is not limited to this, and may be such that the inner or outer peripheral surfaces of the first and second magnetic plates 51, 52 are missing.

The pair of magnetoresistive elements MR1 and MR2 of the magnetic sensor MG1 and the pair of magnetoresistive elements MR3 and MR4 of the magnetic sensor MG2 are placed above the first magnetic plate 51 at an appropriate distance from each other. The first magnetic plate 51 is installed at two positions substantially symmetric with respect to the center of the first magnetic plate 51 at an intermediate portion between the outer periphery and the inner periphery of the plate 51. The magnetoresistive element MR1 (M
R3) and MR2 (MR4) are connected to the notches 51S,
52S are arranged at a distance of a half pitch in the circumferential direction.

Each magnetoresistive element MR1, MR2, MR3
The resistance value of MR4 increases as the magnetic field formed around it increases.

Each magnetoresistive element pair MR1, MR2 and MR
3, rectangular plate-shaped magnets BM1 and BM2 are provided above MR4, respectively, and the magnets BM1 and BM2 are fixed to brackets protruding from circuit portions B1 and B2 fixed to the housing 4, respectively. I have. Further, the magnetoresistive element MR1 is arranged on the terminal side to which the constant voltage V _CC is applied, and the magnetoresistive element MR2 is arranged on the ground terminal side and connected in series.
A voltage divider circuit with the intermediate node as the output node is configured,
It is electrically connected to the circuit section B1 including an amplifier circuit for amplifying an output voltage V _O1 taken out between the magnetoresistive elements MR1 and MR2, an input / output terminal, and the like.

Similarly, the magnetoresistive elements MR3 and MR4 form a voltage dividing circuit with MR3 being the terminal side to which the constant voltage V _CC is applied and MR4 being the ground terminal side, and are connected to the circuit section B2. I have.

FIG. 9 is an electric circuit diagram of the magnetic sensor MG1. Such a magnetic sensor MG1 obtains an output voltage according to the strength of the magnetic field according to the principle described in detail below. That is, the first and second magnetic plates 5 are provided around the magnet BM1.
The magnetic flux density in the vicinity of the magnetic materials 1 and 52 is high, and notches 5
A magnetic field in a state where the magnetic flux density is low in a portion where 1S and 52S overlap is formed, and according to the strength of the magnetic field formed around the magnetoresistive elements MR1 and MR2, the respective magnetoresistive elements MR1 and MR2 have respective resistances. Change the value. on the other hand,
It is adapted to apply a constant voltage V _CC from the circuit unit B1 to the divider circuit by the magnetoresistance element MR1, MR2. The output voltage V _{O1 of the} voltage divider circuit with respect to this constant voltage V _CC
Corresponds to the ratio of the resistance values of the respective magneto-resistive elements MR1 and MR2, and amplifies the output voltage V _O1 to obtain the output voltage V ₁ of the magnetic sensor MG1.

FIG. 10 is an explanatory diagram showing the principle of torque detection in the first embodiment of the torque sensor according to the present invention. The position of the first magnetic plate 51 when the magnetic sensor MG1 is located at the center of one notch 51S is set as a reference position,
When the first magnetic plate 51 is located at the reference position, the magnetic sensors MG1 and MG2 are positioned such that the magnetic sensor MG2 is located at the midpoint between two adjacent notches 51S, 51S.
Is located.

First magnetic plate 51 and second magnetic plate 52
Rotates with the input shaft and the output shaft, respectively, so that the facing areas of the notches provided respectively change according to the relative angular displacement. At this time, for the reason described above, the strength of the magnetic field is weak in the portion where the notches overlap, and the magnetic flux is more concentrated in the portion where the first and second magnetic plates 51 and 52 overlap, so Strength is increasing.

FIG. 11 is an explanatory diagram showing the positional relationship between the notches 51S and 52S and the magnetoresistive elements MR1 and MR2.

Therefore, as shown in FIG. 11A, when the magnetoresistive element pair MR1 and MR2 of the magnetic sensor MG1 are located on the magnetic material of the first and second magnetic plates 51 and 52, A magnetic field of approximately the same strength is formed around the magnetoresistive elements MR1 and MR2, and their respective resistance values are substantially equal. The output voltage of the magnetic sensor MG1 at this time is V
_1a .

As shown in FIG. 11B, the first and second
When the magnetic plates 51 and 52 are rotated and the magnetoresistive element MR1 is located above the notch and the magnetoresistive element MR2 is located above the magnetic material, the magnetic field formed around the magnetoresistive element MR1 is reduced. The intensity is lower than the intensity of the magnetic field formed around the magnetoresistive element MR2. Therefore, the resistance value of the magnetoresistive element MR1 is low, the resistance value of the magnetoresistive element MR2 is high, and the output voltage of the magnetic sensor MG1 is V _1b higher than V _1a .

Further, the first and second magnetic plates 51 and 52 rotate, and as shown in FIG.
And MR2 are located above the notches, respectively, a magnetic field of approximately the same strength is formed around the magnetoresistive elements MR1 and MR2, and their respective resistance values are substantially equal,
The output voltage of the magnetic sensor MG1 becomes _V1a again.

As shown in FIG. 11D, the first and second
When the magnetic plates 51 and 52 rotate and the magnetoresistive element MR1 is positioned above the magnetic material and the magnetoresistive element MR2 is positioned above the notch, the strength of the magnetic field formed around the magnetoresistive element MR1 is increased. The magnitude becomes stronger than the strength of the magnetic field formed around the magnetoresistive element MR2. Therefore, the magnetoresistive element M
The resistance of R1 is high, the resistance value of the magnetoresistance element MR2 is low, the output voltage of the magnetic sensor MG1 becomes lower V _1c than V _1a.

Further, as the first and second magnetic plates 51 and 52 rotate, the magnetoresistive elements MR1 and MR2 are again rotated.
Is located on the magnetic material. Thus, when the first and second magnetic plates 51, 52 rotate, the magnetic sensors MG1,
Output voltage V _1, V ₂ of MG2 changes.

In particular, when the rotation of the first and second magnetic plates 51 and 52 is at a constant angular velocity, the output voltage V
₁ indicates a sinusoidal change. At this time, since the magnetic sensor MG1, MG2 in a position as described above is arranged, the output voltage V ₂ shows a change in a cosine wave.

Accordingly, the outputs of the magnetic sensors MG1 and MG2
Force voltage V₁And V_TwoAnd the above-described base of the first magnetic plate 51.
Equation (1) and equation (1)
Indicated by (2). V₁= C₁・ Sin (nθ) + V_OS1 ... (1) V_Two= C_Two・ Cos (nθ) + V_OS2 ... (2) where C₁, C_TwoIs the output voltage V₁, V_TwoPeriodic variation of
, N is the total number of notches, θ is the first magnetic plate 51
Rotation angle between adjacent reference positions, V_OS1, V_{OS Two}Is my husband
The bias voltage of each of the magnetic sensors MG1 and MG2
You.

Further, when a torque is applied to the input shaft 1 and a relative angle change occurs between the input shaft 1 and the output shaft 2, as described above, the first and second magnetic plates 51 and 52 are applied to the first and second magnetic plates 51 and 52. The facing area of the provided notch changes. When the facing area is large, as shown in FIG. 2A, the number of the magnetic material is reduced and the magnetic flux concentrates on the magnetic material, so that the difference between the density and the density of the magnetic flux is large. Conversely, when the facing area is small, as shown in FIG. 2 (b), the portion of the magnetic material becomes large, and the magnetic flux is distributed almost uniformly, so that the difference between the density and the density of the magnetic flux is small. According to such a principle, the amplitude of the periodic change of the output voltages V ₁ and V ₂ described above changes with the change of the opposing area, and becomes larger as the opposing area is larger and smaller as the opposing area is smaller.

Therefore, the following equations (3) and (4) are derived from the above equations (1) and (2). V ₁ = C ₁ (T) · sin (nθ) + V _OS1 (3) V ₂ = C ₂ (T) · cos (nθ) + V _OS2 (4)

Where T is the steering torque and C
₁ (T) and C ₂ (T) are the magnetic sensors MG1 and MG2, respectively.
Is a fluctuation component of the output voltage due to the fluctuation of the steering torque.

Here, by adjusting the sensitivities of the magnetic sensors MG1 and MG2 so that C ₁ (T) = C ₂ (T), the equations (3), (4) to (5) and (5) are used. Equation (6) is obtained. tan (nθ) = (V ₁ −V _OS1 ) / (V ₂ −V _OS2 ) (5) θ = arctan {(V ₁ −V _OS1 ) / (V ₂ −V _OS2 )} / n (6)

The angle θ has two solutions in the range of 0 ° to 360 ° / n, and is specified as one depending on whether V ₁ is larger than V _OS1 or V ₂ is larger than V _OS2. can do. The control unit 53 including an MPU connected to input the output voltages of the magnetic sensors MG1 and MG2 counts the number of notches that have passed through the magnetic sensors MG1 and MG2. The steering angle is obtained from the angle θ.

The following equations (7) and (8) are obtained from equations (3) and (4). C ₁ (T) = (V ₁ −V _OS1 ) / sin (nθ) (7) C ₂ (T) = (V ₂ −V _OS2 ) / cos (nθ) (8)

A higher numerical value is selected from Expression (7) or Expression (8), and the torque T is obtained from the relationship between the torque T and the amplitude C ₁ (T). FIG. 12 is a graph showing an example of the relationship between the torque T and the amplitude C ₁ (T).

The magnetic sensors MG1 and MG2 may be based on Hall elements.

The magnetic field may be formed by magnetizing the first and second magnetic plates 51 and 52 without using a magnet.

The relationship between the torque T and the angle θ with respect to the values of the output voltages V ₁ and V ₂ is stored in a memory of the control unit 53 as a reference table, and the steering torque T and the angle θ are stored based on the output voltages V ₁ and V _2. May be calculated backward.

Embodiment 2 FIG. 13 is an explanatory view showing the principle of torque detection of a torque sensor according to Embodiment 2 of the present invention. As described in the first embodiment, the first and second magnetic plates 51 and 52 are magnetized such that the N pole is on the upper side and the S pole is on the lower side. Four notches 51S, 51S, 51S, 51S, which are long in one direction, are provided at four positions of the first magnetic plate 51, which are arranged at 90 ° intervals in the circumferential direction.
Are provided at a predetermined angle with respect to the radial direction at each of the above-mentioned positions. The second magnetic plate 52 is provided with a corresponding one of the notches 51S, 51S, 51S, 51S. Four notches 52S, 52S, 52S, 52S are provided symmetrically in the radial direction.
That is, the notches 51S, 51S, 51S, 51S and the notches 52S, 52S, 52S, 52S corresponding thereto.
Are provided so as to intersect when the first and second magnetic plates 51 and 52 are viewed in plan. The notch 51
S, 51S, 51S, 51S and 52S, 52S, 52
S and 52S are arranged at equal intervals in the circumferential direction of the first and second magnetic plates 51 and 52, respectively.

Further, the magnetoresistive element M of the magnetic sensor MG1
R1 and MR2 are provided at appropriate distances above the first magnetic plate 51, and the notches 51S are provided with the magnetoresistive elements MR1 and MR2.
, The magnetoresistive element MR1 is located near the outer end of one notch 51S, and the magnetoresistive element MR2
Is located near the inner end of the notch 51S so that the straight line connecting the magnetoresistive elements MR1 and MR2 is parallel to the notch 51S.

On the other hand, the magnetoresistive element M of the magnetic sensor MG2
R3 and MR4 are provided at appropriate distances above the first magnetic plate 51, and the notches 52S are provided with the magnetoresistive elements MR3 and MR4.
, The magnetoresistive element MR3 is located near the outer end of the notch 52S corresponding to the notch 51S, and the magnetoresistive element MR4 is located near the inner end of the notch 52S. The magnetoresistive elements MR3 and MR4 are set so that a straight line connecting them is parallel to the notch 52S.

The magnetoresistive elements MR1, MR2, MR
Magnetoresistive element MR having the same positional relationship as MR3, MR4
5, MR6, MR7, and MR8 are the MR elements MR.
1, MR2, MR3 and MR4 are a pair of notch pairs 51
The input shaft and the output shaft from the arrangement positions of the magnetoresistive elements MR1, MR2, MR3, and MR4 are positioned so as to be located in the portion where the notches 51S and 52S do not exist when located in the portion where S, 52S exists. Are disposed at a position separated by 45 ° in the rotation direction of. Magnetoresistance element MR5, MR6
Is a detection element of the magnetic sensor MG3, and the magnetoresistive elements MR7 and MR8 are detection elements of the magnetic sensor MG4.

When there is no input of the steering torque and the steering angle, the first and second magnetic plates 51 and 52 are arranged so that the notches 51S and 52S intersect at the respective middle points.
Gap S which is the intersection of two notch pairs 51S, 52S
Are positioned at the center thereof.
2, MR3 and MR4 are arranged. Magnetic sensor MG
Reference numeral 1 denotes a voltage dividing circuit in which the magnetoresistive element MR1 is arranged on the terminal side to which the constant voltage V _CC is applied, the magnetoresistive element MR2 is arranged on the ground terminal side and connected in series, and the intermediate node is an output node. Similarly, the magnetic sensor MG2 is formed by a voltage dividing circuit in which the magnetoresistive element MR3 is arranged on the terminal side to which the constant voltage V _CC is applied, and the magnetoresistive element MR4 is arranged on the installation terminal side.

The magnetic sensors MG3 and MG4 have the same configuration as the magnetic sensors MG1 and MG2.

Therefore, the magnetic sensors MG1, MG2, MG
3 and MG4 are magnetoresistive elements MR1, MR3 and MR, respectively.
5, when the gap S approaches the MR7 side, the output voltage increases and the magnetoresistive elements MR2, MR4, MR6,
When the gap S approaches the MR8 side, the output voltage is reduced.

FIG. 14 is a graph showing the relationship between the circumferential position of the gap S and the output voltage of the magnetic sensor MG1. FIG. 15 is a graph showing the relationship between the circumferential position of the gap S and the magnetic sensor MG2. 4 is a graph showing a relationship with an output voltage. In the figure, the vertical axis indicates the output voltage, and the horizontal axis indicates the circumferential position of the gap S. Due to the rotation of the first and second magnetic plates 51 and 52, the gap S is formed in the magnetoresistive elements MR2 and MR3.
From the line A side connecting, when moving to the straight line B side connecting magnetoresistive element MR1, MR4, the output voltage of the magnetic sensor MG1 from the output value V _1A position of the straight line A, the output value V _1A larger linear The output value at the position B increases to V _1B . on the other hand,
The output voltage of the magnetic sensor MG2 from the output value V _2A position of the straight line A, decreases the output value V _2B position of the output value V _2A smaller linear B. When there is a gap S at the position of the straight line A, it is when the difference between the magnetic flux density around the magnetoresistive element MR1 and the magnetic flux density around the magnetoresistive element MR2 is large, and in either direction from this position. Even when there is a deviation, the difference between the levels of the magnetic flux density becomes small. On the other hand, when there is a gap S at the position of the straight line B, it is when the difference between the magnetic flux density around the magnetoresistive element MR1 and the magnetic flux density around the magnetoresistive element MR2 is large. , The difference between the low and high magnetic flux densities becomes small.

Similarly, when there is a gap S at the position of the straight line A, the difference between the magnetic flux density around the magnetoresistive element MR3 and the magnetic flux density around the magnetoresistive element MR4 is large. Yes, when there is a gap S at the position of the straight line B,
Magnetic flux density around the magnetoresistive element MR3 and the magnetoresistive element M
This is when the difference between the magnetic flux density around R4 and the height is large.

FIG. 16 shows the position of the gap S in the radial direction and the magnetic field.
FIG. 7 is a graph showing a relationship with an output voltage of an air sensor MG1.
FIG. 17 shows the radial position of the gap S and the magnetic sensor.
It is a graph which shows the relationship with MG2 output voltage. In the figure
The vertical axis represents the output voltage, and the horizontal axis represents the radial direction of the air gap S.
Indicates the position. Of the first and second magnetic plates 51 and 52
Due to the change in the relative angle, the gap S is shifted to the radially outer position C.
When the magnetic sensor MG1 moves to the inside position D from
The output voltage is the output value V at the position C._1CFrom the output value V_1CYo
Output value V at position D_1DTo decrease. Similarly, magnetic
The output voltage of the sensor MG2 is the output value V of the position C._2CFrom
The output value V_2COutput value V at smaller position D _2DDecrease to
You.

Accordingly, the position of the gap S changes in the circumferential direction of the first and second magnetic plates 51 and 52 due to the change in the steering torque, and changes in the first and second positions due to the change in the steering angle.
In the radial direction of the magnetic plate 52. For this reason, the steering torque T is equal to the output voltages V ₁ and V of the magnetic sensors MG1 and MG2.
₂ , the angle θ is the output voltage V
It can be determined by the difference of _1, V _2. The memory 53 of the control unit stores two reference tables respectively indicating the relationship between the torque T and V ₁ + V ₂ and the relationship between the angle θ and V ₁ −V _2, and outputs the output voltages V ₁ , from V ₂ and obtains the steering torque T and the angle theta.

The magnetic sensors MG3 and MG4 have the same configuration as the magnetic sensors MG1 and MG2.

[0075] Further, the control unit 53, V ₁ -V ₂ is greater than a predetermined a predetermined upper limit value C _T, or less than or the examined than a predetermined predetermined lower limit value C _B, V
₁ or -V ₂ is larger than the upper limit, or the time less than the lower limit, the gap portion S is a magnetic sensor MG1 and M
The magnetic sensor MG1 is determined to be out of the detection range of G2.
And the calculation of the torque and the steering angle based on the output value of MG2,
The calculation is switched to torque and steering angle calculation based on the output values of the magnetic sensors MG3 and MG4.

On the contrary, when the torque and the steering angle are calculated based on the output values of the magnetic sensors MG3 and MG4, the difference V between the output voltages of the magnetic sensors MG3 and MG4 is obtained.
₃ or -V ₄ is larger than the upper limit C _T, or the smaller than the lower limit value C _B, the magnetic sensor MG3 and M
The calculation of the torque and the steering angle based on the output value of G4 is switched to the calculation of the torque and the steering angle based on the output values of the magnetic sensors MG1 and MG2.

The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

Note that a magnet may be used without magnetizing the first and second magnetic plates 51 and 52.

In the second embodiment described above, four notches 5 are provided in the first and second magnetic plates 51 and 52, respectively.
Although 1S and 52S are provided, the number is not particularly limited.

Third Embodiment FIG. 18 is a front view showing a structure of a main part of a torque sensor according to a third embodiment of the present invention. Instead of the first magnetic plate 51, a first magnetic cylinder 51 a is fixed to the input shaft 1 at the upper end thereof and is provided so that the lower end is opened, and instead of the second magnetic plate 52. A second magnetic cylinder 52a having a diameter larger than that of the first magnetic cylinder 51a is fixed to the output shaft 2 at the lower end with the lower part of the first magnetic cylinder 51a inserted through the opening at the upper end. It is provided so that.

FIG. 19 shows the first and second magnetic cylinders 51a,
It is a perspective view which shows the structure of 52a. First magnetic cylinder 51a
At the predetermined positions of the upper part of the first magnetic cylinder 52a and the lower part of the second magnetic cylinder 52a, rectangular notches 51aS and 52aS whose longitudinal directions are the axial length directions of the input shaft 1 and the output shaft 2 are equally distributed in the circumferential direction, respectively. There are many. The notch 51aS,
52aS is approximately the same size as the portion of the magnetic body between two adjacent notches.

The magnetic sensor MG1 including the magnetoresistive elements MR1 and MR2 and the magnetic sensor MG2 including the magnetoresistive elements MR3 and MR4 face the notch 51aS at an appropriate distance outside the first magnetic cylinder 51a. As described above. The magnetoresistive elements MR1 (MR3) and MR2 (MR4) are arranged at a distance of a half pitch of the notches 51aS, 52aS in the circumferential direction.

Therefore, since the first magnetic cylinder 51a rotates integrally with the input shaft 1, and the second magnetic cylinder 52a rotates integrally with the output shaft 2, torque is applied to the input shaft 1 and When a relative angle change occurs between the shaft 1 and the output shaft 2, the facing area of the notches 51aS, 52aS provided in the first and second magnetic cylinders 51a, 52a changes. The magnetic sensors MG1 and MG2 detect the rotation of the input shaft 1 and the output shaft 2 and the change in the magnetic field due to the change in the facing area,
The torque and the steering angle can be obtained according to the principle described in the first embodiment.

The other parts that are the same as those in the first embodiment are given the same reference numerals, and description thereof is omitted.

As described in the first embodiment, a magnetic field may be formed by magnetizing the first and second magnetic cylinders 51a and 52a. Further, the shapes of the notches 51aS and 52aS are not limited to rectangles, and may be such that the lower end surface of the first magnetic cylinder 51a and the upper end surface of the second magnetic cylinder 52a are omitted. .

Further, similarly to the second embodiment, the notch 5
The shape of 1aS is appropriately inclined with respect to the axial direction of the input shaft 1 and the output shaft 2, and the shape of the notch 52aS is inclined in the direction opposite to the notch 51aS so that they intersect each other. A magnetoresistive element may be arranged around 51aS and 52aS.

In the first to third embodiments, the magnetic sensor has a magnetoresistive element. However, the magnetic sensor may have a Hall element.

Therefore, since the torque sensor is formed by using a small and inexpensive magnetic sensor, the torque sensor can be made smaller and less expensive than the conventional one.

Further, not only the steering torque but also the steering angle can be obtained.

[0090]

As described in detail above, in the case of the torque sensor according to the first invention, a plurality of notches are provided in each of the first and second magnetic members, and the portion where the notches oppose each other and the magnetic member are formed. It is possible to determine the torque and the steering angle by detecting the difference in the density of the magnetic flux density between the opposing portion and the magnetic sensor, and detecting the change in the relative angle and the rotation angle of the first and second magnetic bodies. Becomes

In the case of the torque sensor according to the second invention, a magnetic field is formed in the vicinity of the first and second magnetic bodies by magnets, and a change in the magnetic field is detected by the magnetic sensor, so that the torque and the steering angle are reduced. It is possible to ask.

In the case of the torque sensor according to the third invention, a magnetic field is formed by the first and second magnetic bodies, and a change in the magnetic field is detected by the magnetic sensor.
The torque and the steering angle can be obtained.

In the case of the torque sensor according to the fourth aspect of the invention, the strength of the magnetic field that periodically changes with the rotation of the input shaft and the output shaft is detected at two points having different phases.
Based on the results detected at the two points, a common angle is obtained from a plurality of angles corresponding to the output voltages of the respective magnetic sensors, whereby the pitch of the notch provided in the first and second magnetic bodies is determined. The steering angle can be detected with the above resolution.

In the case of the torque sensor according to the fifth and seventh aspects, when the input shaft and the output shaft rotate due to the notches equally arranged in the circumferential direction of the magnetic body, the electric output of the magnetic sensor is sinusoidal. It changes regularly like a wave. For this reason,
The torque and the steering angle can be obtained by simple calculations.

In the case of the torque sensor according to the sixth and eighth inventions, the notch provided in the first magnetic body is
The torque is obtained by detecting the radial position of the input shaft and the output shaft of the gap formed by the notch provided in the magnetic body and the steering angle by detecting the circumferential position. Can be obtained.

In the case of the torque sensors according to the fifth and sixth aspects of the present invention, small-sized magnetic detecting elements such as a magnetoresistive element and a Hall element are used, and the first and second disk-shaped magnetic bodies are used. Therefore, it is possible to make a torque sensor smaller than before.

Further, in the case of the torque sensor according to the seventh and eighth aspects, a small magnetic detecting element such as a magnetoresistive element and a Hall element, and first and second cylindrical magnetic bodies are used. Therefore, it is possible to make a torque sensor smaller than before.

In the case of the electric steering device according to the ninth invention, since the torque sensor according to any one of the first to seventh inventions is provided, a dedicated device for detecting the steering angle is not required. The present invention has excellent effects, for example, it is possible to make the device smaller in size.

[Brief description of the drawings]

FIG. 1 is a plan view of first and second magnetic bodies.

FIG. 2 is an explanatory diagram showing a change in a magnetic field around first and second magnetic bodies due to a change in a facing area of a notch, in a cross section taken along line II-II in FIG.

FIG. 3 is a graph showing a relationship between an electric output of two magnetic sensors and a steering angle.

FIG. 4 is an explanatory diagram showing a moving direction of a gap.

FIG. 5 is an explanatory diagram showing a moving direction of a gap.

FIG. 6 is a front view showing a configuration of a main part of the torque sensor according to the first embodiment of the present invention.

FIG. 7 is a schematic diagram showing a configuration of a main part of an electric steering device using a torque sensor according to the present invention.

FIG. 8 is a perspective view showing a configuration of a main part of the torque sensor according to the first embodiment of the present invention.

FIG. 9 is an electric circuit diagram of the magnetic sensor.

FIG. 10 is a first embodiment of a torque sensor according to the present invention.
FIG. 4 is an explanatory diagram showing the principle of torque detection of FIG.

FIG. 11 is an explanatory diagram showing a positional relationship between a notch and a magnetoresistive element.

FIG. 12 is a graph illustrating an example of a relationship between a torque and an amplitude of an output waveform of a magnetic sensor.

FIG. 13 is a second embodiment of the torque sensor according to the present invention.
FIG. 4 is an explanatory diagram showing the principle of torque detection of FIG.

FIG. 14 is a graph showing the relationship between the circumferential position of the gap and the output voltage of the magnetic sensor.

FIG. 15 is a graph showing the relationship between the circumferential position of the gap and the output voltage of the magnetic sensor.

FIG. 16 is a graph showing the relationship between the radial position of the gap and the output voltage of the magnetic sensor.

FIG. 17 is a graph showing the relationship between the radial position of the gap and the output voltage of the magnetic sensor.

FIG. 18 is a third embodiment of the torque sensor according to the present invention.
FIG. 2 is a front view showing a configuration of a main part of FIG.

FIG. 19 is a perspective view showing a configuration of first and second magnetic cylinders.

FIG. 20 is a longitudinal sectional view showing a configuration of a conventional electric steering device.

[Description of Signs] 1 input shaft 2 output shaft 3 connecting shaft 4 housing 5 torque sensor 51 first magnetic plate 52 second magnetic plate 51a first magnetic cylinder 52a second magnetic cylinder 51S, 52S, 51aS, 52aS Notch M Electric motor MG1-MG4 Magnetic sensor MR1-MR8 Magnetic resistance element

Claims (9)

[Claims] 1. A torque sensor for detecting a torque applied to an input shaft by a torsion angle generated in a connecting shaft connecting the input shaft and the output shaft, wherein a plurality of notches are provided, and the input shaft and the output shaft are provided with a plurality of notches. First and second magnetic bodies each having an opposing portion and being attached to face each other, and an electric output according to the strength of the magnetic field, arranged near the first and second magnetic bodies. And a magnetic sensor for obtaining the torque from the strength of the magnetic field detected by the magnetic sensor. 2. The torque sensor according to claim 1, wherein a magnet is arranged near the first and second magnetic bodies. 3. The torque sensor according to claim 1, wherein the first and second magnetic bodies are respectively magnetized. 4. When each magnetic sensor is located at a position facing one notch, another magnetic sensor is located at a position facing an intermediate portion between two adjacent notches. 4. The torque sensor according to claim 1, further comprising a sensor. 5. The magnetic recording medium according to claim 1, wherein the first and second magnetic bodies have a disk shape, and the cutouts are radially arranged on the first and second magnetic bodies. The torque sensor according to any one of the above. 6. The first and second magnetic bodies are disc-shaped, and the notches are formed such that the notches of the first magnetic body and the second magnetic bodies cross each other. The torque sensor according to any one of claims 1 to 3, wherein the torque sensor is provided in the circumferential direction of the first and second magnetic bodies. 7. The first and second magnetic bodies have a cylindrical shape, and the notch is long in an axial direction of an input shaft and an output shaft, and has a circumference of the first and second magnetic bodies. The torque sensor according to claim 1, wherein the torque sensors are evenly arranged in the directions. 8. The notch of the first magnetic body and the notch of the second magnetic body intersect with each other in the first and second magnetic bodies having a cylindrical shape. The torque sensor according to any one of claims 1 to 3, wherein the torque sensor is arranged in the circumferential direction of the first and second magnetic bodies. 9. The torque sensor according to claim 1, which is attached to an input shaft and an output shaft, and is driven and controlled based on a torque detected by the torque sensor. An electric steering device comprising: a steering assist electric motor attached to a connected steering mechanism.