JP2014019264A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device allowing obtaining of highly accurate steering angle information of a steering wheel.SOLUTION: A power steering device includes: a torque sensor detecting steering torque generated in a steering shaft on the basis of a relative rotary angle of a first rotary angle to be a rotary angle of an input shaft and a second rotary angle to be a rotary angle of an output shaft; a number of rotation of handle arithmetic circuit calculating the number of rotation of a handle showing the number of rotation from a neutral state in which a rotation position of the steering wheel is the rotation position of the steering wheel when a turning wheel is directed in a straight-ahead direction on the basis of the combination of a third rotary angle to be a rotary angle of a first gear rotated according to rotation of the steering shaft and a fourth rotary angle to be a rotary angle of a second gear rotated by the first gear with a prescribed gear reduction ratio which is not mutually divisible with the first gear; and an absolute angle arithmetic circuit calculating an absolute angle to be rotation amount from the neutral state of the steering wheel on the basis of the first rotary angle or the second rotary angle and the number of rotation of the handle.

Description

  The present invention relates to a power steering apparatus.

  As this type of technology, the technology described in Patent Document 1 below is disclosed. In this publication, the rotation angle of a plurality of gears with different numbers of teeth equipped with a magnet is detected by a magnetic detection element, and the rotation angle of the steering is detected by performing a predetermined calculation by a control means using the detected rotation angle. What to do is disclosed.

JP 2009-192456 A

However, in the technique disclosed in Patent Document 1, since the rotation angle of the steering (steering angle) is detected using the rotation angles of a plurality of gears meshing with each other, a meshing error between the gears is detected. There is a problem in that the accuracy may be affected and high-precision rotation angle information may not be obtained.
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a power steering device capable of obtaining steering angle information of a steering wheel with high accuracy.

  In order to achieve the above object, in the present invention, a first rotation angle sensor that is provided on the input shaft side and detects a first rotation angle that is a rotation angle of the input shaft and a rotation shaft that is provided on the output shaft side and rotates the output shaft. A second rotation angle sensor that detects a second rotation angle that is an angle, and a torque sensor that detects a steering torque generated in the steering shaft based on a relative rotation angle between the first rotation angle and the second rotation angle And a third rotation angle sensor for detecting a third rotation angle that is a rotation angle of the first gear, and the first gear is divisible by the first gear. A fourth rotation angle sensor having a second gear rotated by the first gear with no predetermined reduction ratio and detecting a fourth rotation angle that is a rotation angle of the second gear; and an electronic control unit A steering wheel based on the combination of the third and fourth rotation angles. A rotation number calculation circuit for calculating the number of rotations of the steering wheel indicating the number of rotations from the neutral state, which is the rotation position of the steering wheel when the steered wheel is directed straight, and a first rotation angle or An absolute angle calculation circuit that calculates an absolute angle that is a rotation amount from the neutral state of the steering wheel based on the second rotation angle and the number of times of rotation of the steering wheel is provided.

  According to the present invention, it is possible to obtain steering angle information of a steering wheel with high accuracy.

1 is an overall schematic diagram of a power steering apparatus according to a first embodiment. It is a disassembled perspective view of the steering angle sensor and steering torque sensor of Example 1. FIG. It is sectional drawing of the steering angle sensor of Example 1, and steering torque sensor vicinity. It is a figure which shows the relationship between the rotation angle of the input shaft of Example 1, and the rotation angle of a primary detection gear and a secondary detection gear. It is a figure which shows the relationship with the rotation angle of the input shaft of Example 1, and the detection angle of a secondary resolver. It is a figure which shows the relationship between the rotation angle of the input shaft of Example 1, the absolute steering angle of a steering angle sensor, and the detection angle of a primary resolver. 6 is a flowchart illustrating a flow of processing for obtaining the number of resets of the primary resolver according to the first embodiment. It is a figure which shows the relationship between the rotation angle of the input shaft of another Example, the absolute steering angle of a steering angle sensor, and the detection angle of a primary resolver. It is a whole schematic diagram of the single pinion type power steering device of other examples.

[Example 1]
[Overall configuration of power steering system]
A power steering apparatus 1 according to the first embodiment will be described. FIG. 1 is an overall schematic diagram of the power steering apparatus 1. The power steering device 1 includes a steering wheel 2, an input shaft 3 connected to the steering wheel 2, an output shaft 4 connected to the input shaft 3, a first pinion shaft 5 connected to the output shaft 4, The rack bar 6 meshes with the one pinion shaft 5, the tie rod 7 connected to the end of the rack bar 6, and the steered wheels 8 connected to the tie rod 7. First rack teeth 6a are formed at positions where the first pinion shaft 5 and the rack bar 6 mesh with each other.
A torsion bar 22 is provided between the input shaft 3 and the output shaft 4, and the input shaft 3 and the output shaft 4 are configured to be rotatable relative to each other within a torsion range of the torsion bar 22 (FIG. 3). reference). The input shaft 3 and the output shaft 4 constitute a steering shaft 26. The first pinion shaft 5 and the rack bar 6 constitute a conversion mechanism 27 that converts the rotation operation of the output shaft 4 into the turning operation of the steered wheels 8. A steering mechanism 28 is constituted by the steering shaft 26 and the conversion mechanism 27.

As a steering assist mechanism for assisting the steering force of the steering wheel 2, the electric motor 9, the worm shaft 10 connected to the output shaft of the electric motor 9, the worm wheel 11 meshing with the worm shaft 10, and the worm wheel 11 are connected. The second pinion 12 is provided. The second pinion 12 meshes with second rack teeth 6 b provided on the rack bar 6.
A steering angle sensor 13 for detecting the steering angle of the steering wheel 2 is provided on the outer periphery of the input shaft 3, and a steering torque for detecting the steering torque input to the steering wheel 2 is provided between the input shaft 3 and the output shaft 4. A sensor 14 is provided.
As a configuration for controlling the electric motor 9, an electronic control unit 15 is provided. The electronic control unit 15 includes a motor electronic control unit 16 and a sensor electronic control unit 17. The motor electronic control unit 16 has a motor command value calculation unit 18 that calculates a command current to the electric motor 9 based on the steering torque detected by the steering torque sensor 14. The sensor electronic control unit 17 calculates the number of rotations of the handle indicating the number of rotations of the steering wheel 2 indicating the number of rotations from the neutral state, which is the rotation position of the steering wheel when the steered wheels 8 are directed straight. A number calculation unit 19 and an absolute angle calculation unit 20 that calculates an absolute angle that is a rotation amount from the neutral position of the steering wheel 2 are provided.

[Configuration of steering angle sensor]
2 is an exploded perspective view of the steering angle sensor 13 and the steering torque sensor 14, and FIG. 3 is a cross-sectional view of the vicinity of the steering angle sensor 13 and the steering torque sensor 14. Here, the configuration of the steering angle sensor 13 will be mainly described.
The steering angle sensor 13 has a main gear 13a that rotates integrally with the input shaft 3, a primary detection gear 13b that meshes with the main gear 13a, and a secondary detection gear 13c that meshes with the primary detection gear 13b. The main gear 13a is composed of, for example, 40-tooth gear, the primary detection gear 13b is composed of 20-tooth gear, and the secondary detection gear 13c is composed of 19-tooth gear. That is, the number of teeth of the primary detection gear 13b and the number of teeth of the secondary detection gear 13c are set to a number that is not divisible by each other.
The primary detection gear 13b and the secondary detection gear 13c are mounted with magnetic members 13h and 13i magnetized with N and S poles, respectively, at a predetermined interval in the circumferential direction. Magnetoresistive sensors 13d and 13e that detect changes in the magnetic field generated between the north and south poles of the magnetic members 13h and 13i as changes in the resistance value of the resistance element are provided at positions facing the magnetic members 13h and 13i. It has been. The magnetoresistive effect sensors 13d and 13e are mounted on the substrate 21. Each element of the steering angle sensor 13 is housed in a steering angle sensor case 13f. One side of the steering angle sensor case 13f is opened, and after accommodating the elements of the steering angle sensor 13, the substrate 21 is accommodated on the opening side of the steering angle sensor case 13f, and is closed by the steering angle sensor cover 13g.

[Configuration of steering torque sensor]
The configuration of the steering torque sensor 14 will be described with reference to FIGS. The steering torque sensor 14 includes a primary resolver 29 that detects the rotation angle of the input shaft 3 and a secondary resolver 30 that detects the rotation angle of the output shaft 4. The primary resolver 29 has a primary rotor 29a that rotates integrally with the input shaft 3, and a primary stator 29b that is disposed facing the radially outer side of the primary rotor 29a. The secondary resolver 30 includes a secondary rotor 30a that rotates integrally with the output shaft 4, and a secondary stator 30b that is disposed to face the radially outer side of the secondary rotor 30a and detects the rotation angle of the output shaft 5. .
The primary rotor 29a and the secondary rotor 30a are accommodated in the steering torque sensor case 14e, and the opening of the steering torque sensor case 14e is closed by the bottom of the steering angle sensor case 13f. The primary stator 29b and the secondary stator 30b are attached to the steering torque sensor case 14e. Further, a harness 23 is connected to the substrate 21 and the harness 23 outputs information to the outside.
The steering angle sensor 13 and the steering torque sensor 14 are accommodated in the gear housing 24 together with the first pinion shaft 5, and the opening of the gear housing 24 is closed by the gear cover 25.

[How to find the steering angle]
FIG. 4 is a diagram showing the relationship between the rotation angle of the input shaft 3 and the rotation angles of the primary detection gear 13b and the secondary detection gear 13c. From the magnetoresistive effect sensors 13d and 13e, magnetic field changes of the magnetic members 13h and 13i that change in accordance with the rotational positions of the primary detection gear 13b and the secondary detection gear 13c are caused by changes in magnetoresistance, sine wave signals or cosine wave signals. FIG. 4 shows a signal converted from this sine wave signal or cosine wave signal into rotation angle information.
As shown in FIG. 4, the 19-tooth secondary detection gear 13c rotates one or more times while the 20-tooth primary detection gear 13b rotates once. As the number of rotations increases until the secondary detection gear 13c rotates 20 times, the difference in the number of rotations of the secondary detection gear 13c with respect to the primary detection gear 13b increases. The absolute steering angle (the absolute rotation angle of the input shaft 3) can be obtained using this rotational speed difference.

[How to find steering torque]
FIG. 5 is a diagram showing the relationship between the rotation angle of the input shaft 3 and the detection angles of the primary resolver 29 and the secondary resolver 30. The primary resolver 29 and the secondary resolver 30 output magnetic field changes that change according to the rotational positions of the input shaft 3 and the output shaft 4 as sine wave signals or cosine wave signals. The wave signal is converted into rotation angle information.
Since the torsion bar 22 is provided between the input shaft 3 and the output shaft 4, the torsion bar 22 is twisted due to the steering torque input to the steering wheel 2, and between the input shaft 3 and the output shaft 4. Rotational angle difference occurs. This rotation angle difference appears as a difference between the detection angle of the primary resolver 29 and the detection angle of the secondary resolver 30, as shown in FIG. If this detection angle difference is multiplied by the Young's modulus of the torsion bar 22, the steering torque can be obtained.

[How to find the steering angle (high accuracy type)]
The method for obtaining the steering angle of the steering angle sensor 13 alone has been described above, but in the steering angle sensor 13, the main gear 13a, the primary detection gear 13b, and the secondary detection gear 13c are constituted by gears that mesh with each other, The meshing error due to backlash or the like affects the accuracy of the detected angle, and there is a possibility that highly accurate steering angle information cannot be obtained.
In the first embodiment, in order to obtain more accurate steering angle θsp information, the steering angle is obtained by the method described below. FIG. 6 is a diagram showing the relationship between the rotation angle of the input shaft 3, the absolute steering angle of the steering angle sensor 13, and the detection angle of the primary resolver 29.
First, using the absolute steering angle θs detected by the steering angle sensor 13 and the maximum rotation angle θrmax detectable by the primary resolver 29, the number of resets of the primary resolver 29 is obtained. The maximum rotation angle θrmax is a constant determined in advance from the configuration of the primary resolver 29.

FIG. 7 is a flowchart showing the flow of processing for obtaining the number of resets of the primary resolver 29.
In step S1, the absolute steering angle θs detected by the steering angle sensor 13 is calculated, and the process proceeds to step S2.
In step S2, the maximum rotation angle θrmax of the input shaft 3 that can be detected by the primary resolver 29 is called, and the process proceeds to step S3.
In step S3, the reset count n is obtained by the following equation, and the process proceeds to step S4.
n = θs / θrmax (where n is an integer, rounded down after the decimal point)
In step S4, the reset count n is output and the process is terminated.
The calculation process of the reset number n is calculated by the handle rotation number calculation unit 19.
Next, the steering angle θsp is obtained from the reset number n of the primary resolver 29 and the detected angle θr of the primary resolver 29. The steering angle θsp can be obtained from the following equation.
θsp = θrmax × n + θr
The calculation process of the steering angle θsp is calculated by the absolute angle calculation unit 20.
That is, the approximate number of resets n is obtained using the absolute steering angle θs detected by the steering angle sensor 13 having a large error, and a high-precision steering angle θsp is obtained by combining with the detection angle θr of the primary resolver 29 having a small error. I have to.
Further, the steering angle θsp can be obtained as follows.
Using the absolute steering angle θs detected by the steering angle sensor 13, the rotational position of the steering wheel 2 is rotated from the neutral position, which is the rotational position of the steering wheel 2 when the steered wheel 8 is directed straight, by the following formula: Find the handle rotation number N that indicates whether it is in the eyes
N = θs / 360 ° (where N is an integer, rounded down after the decimal point)
The calculation process of the handle rotation number N is calculated by the handle rotation number calculation unit 19.
Next, the number of resets n1 of the primary resolver 29 after the handle rotation number N is obtained by the following equation.
n1 = (θs-360 ° × N) / θrmax (where n1 is an integer, rounded down after the decimal point)
Next, the steering angle θsp is obtained from the reset number n1 of the primary resolver 29 and the detected angle θr of the primary resolver 29. The steering angle θsp can be obtained from the following equation.
θsp = (360 ° × N) + (θrmax × n1) + θr
The calculation process of the steering angle θsp is calculated by the absolute angle calculation unit 20.
That is, using the absolute steering angle θs detected by the steering angle sensor 13 with a large error, the steering wheel rotation number N and the rough reset number n1 are obtained, and combined with the detection angle θr of the primary resolver 29 with a small error for high accuracy. The steering angle θsp is obtained.

[Action]
In the steering angle sensor 13, since the main gear 13a, the primary detection gear 13b, and the secondary detection gear 13c are configured to mesh with each other, the meshing error due to backlash or the like affects the accuracy of the detected angle, and the highly accurate steering angle Information may not be obtained.
In addition, when trying to detect the full range of steering angle of the steering wheel 2, it is necessary to detect in the range of 720 ° or more on the left and 720 ° or more on the right, and the entire range is calculated by digital processing with limited memory capacity When trying to do so, there is a possibility that sufficient resolution cannot be obtained.
Therefore, in the first embodiment, the absolute number of rotations θrmax that can be detected by the absolute steering angle θs primary resolver 29 detected by the steering angle sensor 13 is used to obtain the number of resets of the primary resolver 29, and the number of resets of the primary resolver 29 is n primary. The steering angle θsp is obtained from the detected angle θr of the resolver 29.
As a result, a rough steering wheel rotation number (reset number n) is obtained using a value (absolute steering angle θs) detected by the steering angle sensor 13 that has a large error but can obtain an absolute steering angle. A highly accurate steering angle θsp can be obtained by combining with a value (detection angle θr) detected by the primary resolver 29 that cannot obtain the steering angle.

In the first embodiment, the primary detection gear 13b and the secondary detection gear 13c include magnetic members 13h and 13i magnetized with N and S poles at predetermined intervals in the circumferential direction, and the magnetoresistive effect sensor 13d and The magnetoresistive effect sensor 13e is composed of a magnetoresistive effect sensor that detects a change in the magnetic field generated between the N pole and the S pole as a change in the resistance value of the resistance element. As a result, the steering angle sensor 13 can be made highly resistant to environmental changes with high response.
In the first embodiment, the electronic control unit 15 receives the output signals from the primary resolver 29, the secondary resolver 30, the magnetoresistive effect sensor 13d, and the magnetoresistive effect sensor 13e as a sine wave signal and a cosine wave signal. A sensor electronic control unit 17 for calculating the rotation angle of the steering shaft 26 using the signal and the cosine wave signal, and a command current to the electric motor 9 based on the calculation result of the sensor electronic control unit 17 provided with the motor command value calculation unit 18 And a motor electronic control unit 16 for calculating a value. Thereby, since the signals of the primary resolver 29, the secondary resolver 30, the magnetoresistive effect sensor 13d, and the magnetoresistive effect sensor 13e are all input to the sensor electronic control unit 17, it is possible to integrate and simplify the arithmetic circuit.

  In the first embodiment, the steering mechanism 28 has a first pinion shaft 5 provided on the output shaft 4, first rack teeth 6 a that mesh with the first pinion shaft 5, and rack teeth that are different from the first rack teeth 6 a. The rack bar 6 formed with the second rack teeth 6b, the second pinion shaft 12 meshing with the second rack teeth 6b, the worm wheel 11 provided on the second pinion shaft 12, and the worm wheel 11 are meshed with each other. And a worm shaft 10 to which the rotational force of the electric motor 9 is applied. As a result, the steering force from the steering wheel 2 is transmitted from the first pinion shaft 5 to the rack bar 6, and the steering assist force from the electric motor 9 is transmitted from the second pinion shaft 12 to the rack bar 6. The load can be distributed to the first pinion shaft 5 and the second pinion shaft 12, and the power steering device 1 with higher output can be provided.

[effect]
The effects of the power steering device 1 of the first embodiment are listed below.
(1) A steering shaft 26 composed of an input shaft 3 that rotates in response to a steering operation of the steering wheel 2 and an output shaft 4 that is connected to the input shaft 3 via a torsion bar 22 and that transmits the rotation of the input shaft 3; A steering mechanism 28 including a conversion mechanism 27 that converts the rotation of the output shaft 4 into a turning operation of the steered wheels 8, an electric motor 9 that applies a steering force to the steering mechanism 28, and drive control of the electric motor 9. An electronic control unit 15; a primary resolver 29 (first rotation angle sensor) that is provided on the input shaft 3 side and detects a first rotation angle that is a rotation angle of the input shaft 3; and an output shaft 4 side. A secondary resolver 30 (second rotation angle sensor) that detects a second rotation angle that is the rotation angle of the output shaft 4, and a steering shaft based on a relative rotation angle between the first rotation angle and the second rotation angle. Steering torque sensor 14 for detecting the steering torque generated in A motor command value calculation unit 18 (motor command value calculation circuit) that is provided in the control unit 15 and calculates a command current value to the electric motor 9 based on the steering torque, and a primary detector that rotates according to the rotation of the steering shaft 26. A magnetoresistive effect sensor 13d (third rotation angle sensor) for detecting a third rotation angle that is a rotation angle of the primary detection gear 13b, and a primary detection gear 13b. A magnet that has a secondary detection gear 13c (second gear) rotated by the primary detection gear 13b with a predetermined reduction ratio that is not divisible by each other, and that detects the fourth rotation angle that is the rotation angle of the secondary detection gear 13c. The resistance effect sensor 13d (fourth rotation angle sensor) and the electronic control unit 15 are equipped with a steering wheel based on the combination of the third rotation angle and the fourth rotation angle. The rotation number of the steering wheel 2 calculates the number of rotations of the steering wheel 19 indicating the number of rotations from the neutral state, which is the rotation position of the steering wheel 2 when the steered wheels 8 are directed straight. Steering wheel rotation number calculation circuit) and an absolute angle calculation unit 20 (absolute angle calculation) that calculates an absolute angle that is a rotation amount from the neutral state of the steering wheel 2 based on the first rotation angle or the second rotation angle and the steering wheel rotation number Circuit).
Therefore, a rough steering wheel rotation number (reset number n) is obtained using a value (absolute steering angle θs) detected by the steering angle sensor 13 that can obtain the absolute steering angle although the error is large. A highly accurate steering angle θsp can be obtained by combining with a value (detection angle θr) detected by the primary resolver 29 where the angle cannot be obtained.

(2) The primary detection gear 13b and the secondary detection gear 13c include magnetic members 13h and 13i magnetized with N and S poles at a predetermined interval in the circumferential direction, and include a magnetoresistive effect sensor 13d and a magnetoresistive effect. The sensor 13e is composed of a magnetoresistive sensor that detects a change in the magnetic field generated between the N pole and the S pole as a change in the resistance value of the resistance element.
Therefore, the steering angle sensor 13 can be made highly resistant to environmental changes with high response.

(3) The electronic control unit 15 receives the output signals from the primary resolver 29, the secondary resolver 30, the magnetoresistive effect sensor 13d, and the magnetoresistive effect sensor 13e as a sine wave signal and a cosine wave signal. A sensor electronic control unit 17 that calculates the rotation angle of the steering shaft 26 using a wave signal and a motor command value calculation unit 18 are provided to calculate a command current value to the electric motor 9 based on the calculation result of the sensor electronic control unit 17 The motor electronic control unit 16 is configured.
Therefore, it is possible to integrate and simplify the arithmetic circuit.

(4) The steering mechanism 28 includes a first pinion shaft 5 provided on the output shaft 4, a first rack tooth 6a that meshes with the first pinion shaft 5, and a second rack that is different from the first rack teeth 6a. Rack bar 6 formed with teeth 6b, second pinion shaft 12 meshing with first rack teeth 6a, worm wheel 11 provided on second pinion shaft 12, meshing with worm wheel 11 and electric motor 9 And a worm shaft 10 to which the rotational force is applied.
Therefore, the power steering device 1 with higher output can be provided.

[Other Examples]
As described above, the present invention has been described based on the first embodiment. However, the specific configuration of each invention is not limited to each embodiment, and even if there is a design change or the like without departing from the gist of the invention. Are included in the present invention.

<Other Example 1>
The first embodiment has been described on the assumption that the initial value of the steering angle detected by the steering angle sensor 13 matches the initial value of the detected angle detected by the primary resolver 29, but when the initial values do not match What is necessary is just to obtain | require absolute steering angle (theta) s as follows.
FIG. 8 is a diagram showing the relationship between the rotation angle of the input shaft 3, the absolute steering angle of the steering angle sensor 13, and the detection angle of the primary resolver 29. First, the number of resets of the primary resolver 29 is obtained in the same manner as in the first embodiment.
Next, the steering angle θsp is obtained from the reset number n of the primary resolver 29 and the detected angle θr of the primary resolver 29. The steering angle θsp can be obtained from the following equation.
θsp = θrmax * r + (θr-θr1)
Θr1 in the equation is a detection angle of the primary resolver 29 at the initial value of the steering angle detected by the steering angle sensor 13, and can be obtained in advance at the time of calibration.

<Other Example 2>
In the first embodiment, the detection angle of the primary resolver 29 is used to obtain a highly accurate steering angle. That is, the steering angle is obtained using the rotation angle of the input shaft 3. Alternatively, the steering angle may be obtained using the detection angle of the secondary resolver 30, that is, the rotation angle of the output shaft. When obtaining the steering angle using the rotation angle of the input shaft 3, it is effective when controlling based on the steering angle of the steering wheel 2, and when obtaining the steering angle using the rotation angle of the output shaft 4, it is effective. This is effective when the control is performed based on the turning angle of the steering wheel 8.

<Other Example 3>
In the first embodiment, the steering force from the steering wheel 2 is transmitted to the rack bar 6 via the first pinion shaft 5, and the steering assist force from the electric motor 9 is transmitted to the rack bar 6 via the second pinion shaft 12. The so-called double pinion type was used. Instead of this, a single pinion type may be used.
FIG. 9 is an overall schematic diagram of the single-pinion type power steering apparatus 1. As shown in FIG. 9, in the single pinion type, a worm wheel 11 is provided on the first pinion shaft 5, and the electric motor 9 applies a steering assist force via a worm shaft 10 that meshes with the worm wheel 11. That is, in the single pinion type, the steering force from the steering wheel and the steering assist force from the electric motor 9 are transmitted to the rack bar 6 via the first pinion shaft 5. Thereby, the power steering device 1 can be downsized.

<Other Example 4>
In the first embodiment, the steering angle sensor 13 includes a main gear 13a, a primary detection gear 13b, and a secondary detection gear 13c, and the number of teeth of the primary detection gear 13b and the secondary detection gear 13c cannot be divided from each other. I tried to be a number. Instead of this configuration, the steering angle sensor 13 is composed of a main gear 13a and a primary detection gear 13b, the number of teeth of the main gear 13a and the primary detection gear 13b is set to an indivisible number of teeth, and the number of rotations of the main gear 13a The absolute steering angle may be obtained from the rotation speed of the primary detection gear 13b.

[Technical thought other than claims]
Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.

(A) In the power steering device according to claim 1,
The electronic control unit receives output signals from the first, second, third and fourth rotation angle sensors as sine wave signals and cosine wave signals, and uses the sine wave signals and cosine wave signals to A sensor electronic control unit for calculating the rotation angle of the steering shaft;
A motor electronic control unit that is provided with the motor command value calculation circuit and calculates a command current value to the electric motor based on a calculation result of the sensor electronic control unit;
A power steering device comprising:
Therefore, it is possible to integrate and simplify the arithmetic circuit.

(B) In the power steering device according to claim 1,
The steering mechanism includes a first pinion shaft provided on the output shaft,
A rack bar formed with first rack teeth that mesh with the first pinion shaft and second rack teeth that are different from the first rack teeth;
A second pinion shaft that meshes with the second rack teeth;
A worm wheel provided on the second pinion shaft;
A worm shaft that meshes with the worm wheel and is provided with a rotational force of the electric motor;
A power steering device comprising:
Therefore, a power steering device with higher output can be provided.

2 Steering wheel
3 Input shaft
4 Output shaft
5 First pinion shaft
6 Rack bar
6a First rack tooth
6b Second rack tooth
8 Steering wheel
9 Electric motor
10 Worm shaft
11 Worm wheel
12 Second pinion shaft
13b Primary detection gear (first gear)
13c Secondary protection gear (second gear)
13d Magnetoresistive sensor (third rotation angle sensor)
13e Magnetoresistive sensor (fourth rotation angle sensor)
13h Magnetic member
13i Magnetic member
14 Steering torque sensor
15 Electronic control unit
16 Motor electronic control unit
17 Sensor electronic control unit
18 Motor command value calculation unit (motor command value calculation circuit)
19 Handle rotation frequency calculator (handle rotation frequency calculation circuit)
20 Absolute angle calculation unit (absolute angle calculation circuit)
22 Torsion bar
26 Steering shaft
27 Conversion mechanism
28 Steering mechanism
29 Primary resolver (first rotation angle sensor)
30 Secondary resolver (second rotation angle sensor)

Claims (2)

A steering shaft composed of an input shaft that rotates in response to a steering operation of the steering wheel, an output shaft that is connected to the input shaft via a torsion bar, and that transmits the rotation of the input shaft, and the rotation of the output shaft A steering mechanism composed of a conversion mechanism for converting into a steering operation of
An electric motor for applying a steering force to the steering mechanism;
An electronic control unit for driving and controlling the electric motor;
A first rotation angle sensor that is provided on the input shaft side and detects a first rotation angle that is a rotation angle of the input shaft; and a second rotation that is provided on the output shaft side and is a rotation angle of the output shaft. A second rotation angle sensor for detecting an angle, and a torque sensor for detecting a steering torque generated in the steering shaft based on a relative rotation angle between the first rotation angle and the second rotation angle;
A motor command value calculation circuit that is provided in the electronic control unit and calculates a command current value to the electric motor based on the steering torque;
A third rotation angle sensor that has a first gear that rotates according to the rotation of the steering shaft, and that detects a third rotation angle that is a rotation angle of the first gear;
A fourth gear that has a second gear that is rotated by the first gear with a predetermined reduction ratio that is not divisible by the first gear, and that detects a fourth rotation angle that is a rotation angle of the second gear. Rotation angle sensor of
Provided in the electronic control unit, based on the combination of the third rotation angle and the fourth rotation angle, from the neutral state where the rotation position of the steering wheel is the rotation position of the steering wheel when the steered wheels are directed straight ahead A handle rotation number calculating circuit for calculating a handle rotation number indicating the number of rotations;
An absolute angle calculation circuit for calculating an absolute angle, which is a rotation amount from a neutral state of the steering wheel, based on the first rotation angle or the second rotation angle and the steering wheel rotation number;
A power steering apparatus comprising: In the power steering device according to claim 1,
The first gear and the second gear include a magnetic member having N poles and S poles magnetized at a predetermined interval in the circumferential direction,
The third rotation angle sensor and the fourth rotation angle sensor are configured by a magnetoresistive effect sensor that detects a change in a magnetic field generated between the N pole and the S pole as a change in the resistance value of a resistance element. A power steering device characterized by that.

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