WO2005043074A1

WO2005043074A1 - Steering angle detection device

Info

Publication number: WO2005043074A1
Application number: PCT/JP2004/016263
Authority: WO
Inventors: Yasuhito Kanno; Masaru Suzuki
Original assignee: Asahi Kasei Emd Corporation; Asahi Kasei Electronics Co., Ltd.
Priority date: 2003-11-04
Filing date: 2004-11-02
Publication date: 2005-05-12
Also published as: JP2005140557A

Abstract

A steering angle detection device accurately detecting a rotation angle of a shaft in spite of its simple structure. Detection signals from a first Hall element (HE1) and a second Hall element (HE2) are inputted into an angle conversion circuit (42), and an angle detection signal SDET representing only a range of 0 degree to 360 degrees is outputted. A detection signal outputted from a third Hall element (HE3) is inputted into a region determination circuit (48), and a signal SROT representing how many times and in which direction a steering shaft (4) has rotated is outputted. An angle output circuit (44) calculates ±N × 360º+SDET (N =0, 1, 2,...) based on SDET and SROT, and outputs a signal Sout.

Description

Specification

Steering angle detector

Technical field

The present invention relates to a steering angle detection device that detects a rotation angle of a shaft that rotates 360 degrees or more.

Background art

[0002] A steering angle sensor detects a rotational position of a steering shaft as an angle based on a true neutral position (so-called absolute steering angle). Since this steering angle sensor is important as one of the sensors used for vehicle control in an automobile or the like, various proposals have been made in the past.

[0003] Patent Document 1 discloses a rotation angle detection device capable of detecting and storing information on the rotation direction and the rotation angle of the steering shaft while the engine is stopped. This rotation angle detection device employs an incremental system that counts the number of ON / OFF signals.

[0004] Patent Document 2 discloses a backup multi-rotation absolute position detector capable of high-speed response even when the main power supply is shut off. In this multi-rotation type absolute position detector, a rotating disk provided with information such that a digital value of "0" or "1" can be detected by the detection element is used, and the detection element detects "0". The gray code method that detects the angle by the combination of '1' and so on is adopted.

[0005] Further, Patent Document 3 discloses a vehicle steering sensor capable of detecting an accurate absolute steering angle early after an ignition key is turned on. This vehicle steering sensor is provided with a rotation speed detection unit using a gear reduction mechanism in order to detect the entire rotation range of the steering wheel.

[0006] In other words, in the related art described in Patent Document 1, it is necessary to continue to detect the steering angle even when the ignition key is turned off, and it is necessary to consider power consumption at this time. Further, in the conventional technology described in Patent Document 2, it is necessary to densify a code applied to a rotating disk with high resolution, and therefore, the number of detection elements increases. Furthermore, these patent documents In the conventional technologies described in 1 and 2, since the coded digital signal is processed, it is necessary to change the overall design according to the specifications of the steering shaft diameter 角度 and the angle resolution for mounting the steering angle sensor. Comes out.

[0007] Further, in the conventional technique described in Patent Document 3, since the number of rotation speed detection units is increased, there is a problem that it is necessary to match the detailed angle detection unit with the reference position of the rotation speed detection unit.

[0008] Therefore, in order to solve the problems described in Patent Documents 13 to 13, Patent Document 4 discloses a method in which the ignition key is not turned on and the detection of steering angle information is not continued when the ignition key is turned off. The present invention discloses a steering angle sensor capable of detecting a steering angle at the same time.

In the invention described in Patent Document 4, the rotation angle range of the steering shaft is converted into “within one rotation” by a gear mechanism, and the angle range of less than one rotation is detected by a magnetic sensor. . That is, a reduction gear mechanism is attached to the steering shaft. This reduction gear mechanism bidirectionally moves the entire rotation angle range of the steering shaft (for example, an angle range of right and left two rotations: 720 degrees on the earth). Rotation angle range of less than one rotation (360 degrees) ". Then, one angle information within 360 degrees is obtained by the output of two Hall elements having different phases provided in two adjacent gaps.

[0010] However, the invention described in Patent Document 4 converts a rotation in the range of ± 720 degrees into a rotation angle of less than 360 degrees by attaching a reduction gear mechanism to the steering shaft. There is a problem that an unavoidable error may occur in the measured value of the rotation angle due to the inherent backlash of the.

As described above, the conventional steering angle detection technology has a problem that highly accurate angle measurement cannot be performed.

Patent Document 1: JP-A-11-264725 (page 1, abstract)

Patent Document 2: JP-A-5-322599 (page 1, abstract)

Patent Document 3: JP-A-11-287608 (page 1, abstract)

Patent Document 4: JP-A-2002-228408 (page 1, abstract, FIG. 1)

Disclosure of the invention [0013] Therefore, an object of the present invention is to provide a steering angle detection device that detects a rotation angle of a shaft accurately with a simple structure in view of the above problems.

[0014] In order to achieve the above object, the present invention provides a steering angle detection device for detecting a rotation angle of a shaft that rotates 360 degrees or more, wherein an annular magnet provided around the shaft; A first angle sensor having a magnetic sensor for detecting a magnetic flux due to rotation of the annular magnet; a second angle sensor for detecting a range of the rotation angle of the shaft; and the first angle sensor. A calculating means for calculating a rotation angle value of the shaft based on an output of the angle sensor and an output of the second angle sensor.

[0015] Further, in the above steering angle detecting device, the second angle sensor includes a dependent gear that rotates in association with each rotation of the shaft, a magnet fixed to the dependent gear, And a magnetic detection element for detecting the position of the magnet. Alternatively, in the steering angle detection device described above, the second angle sensor includes a magnet that moves in parallel with a rotation axis of the shaft in conjunction with the rotation of the shaft, and a magnetic detection that detects a position of the magnet. And an element.

Brief Description of Drawings

FIG. 1 is an external configuration diagram of a steering angle sensor to which the present invention is applied.

FIG. 2A is a diagram showing a plan configuration in a steering angle sensor case 6 according to the first embodiment.

FIG. 2B is a diagram showing a side configuration of a steering angle sensor case 6 in the first embodiment.

FIG. 3 is an enlarged view showing a relationship between a first magnet MG1 mounted on an outer peripheral surface of a steering shaft 4, a first hall element HE1, and a second hall element HE2.

FIG. 4 is a block diagram showing an electric circuit configuration of a steering angle sensor to which the present invention is applied.

FIG. 5 is a waveform chart showing detection signals output from a first Hall element HE1 and a second Hall element HE2.

FIG. 6 is a waveform diagram illustrating an angle detection signal S in FIG. 4.

DET

[FIG. 7] A rotation detection signal S = ± N (N = 0, 1, 2) output from the area determination circuit 48 in FIG.

ROT

FIG.

8 is a waveform diagram illustrating an output signal S obtained from an angle output circuit 44 in FIG. 4.

OUT

FIG. 9A is a diagram showing a plan configuration inside a steering angle sensor case 6 according to a second embodiment. FIG. 9B is a diagram showing a side configuration of the inside of the steering angle sensor case 6 according to the second embodiment.

FIG. 10 is a waveform diagram illustrating a signal obtained from a second angle sensor Hall element HE3 ′ in the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is an external configuration diagram of a steering angle sensor to which the present invention is applied. In this drawing, 2 is a steering wheel, 4 is a steering shaft, and 6 is a case for a steering angle sensor. The steering angle sensor according to the present embodiment is housed in the steering angle sensor case 6.

FIG. 2A shows a plan configuration inside the steering angle sensor case 6, and FIG. 2B shows a side configuration of the steering angle sensor case 6. In the figure, a first magnet MG1 is concentrically mounted on the outer peripheral surface of the steering shaft 4. Then, in order to detect a magnetic field generated by the first magnet MG1, the first Hall element HE1 and the second Hall element HE2 are fixedly arranged in a non-contact state with the first magnet MG1. These two Hall elements HE1 and HE2 are arranged on concentric circles that are displaced by approximately 90 degrees with respect to the rotation center axis of the steering shaft 4. As described later in detail, based on the two detection signals obtained from the first Hall element HE1 and the second Hall element HE2, the current position of the steering shaft 4 is changed by 0 ° to 360 °. Measure over a range. In other words, the position at which the steering shaft 4 rotates left or right regardless of how many times it has turned is detected as 0 ° -360 ° information.

Further, a main gear 10 is attached to the steering shaft 4, and the projection 10 a rotates with the rotation of the steering shaft 4. That is, every time the steering shaft 4 makes one rotation, the projection 10a also makes one rotation. A dependent gear 20 is provided in a form that meshes with the main gear 10. The dependent gear 20 has protrusions 20a to 20f that engage with the protrusions 10a. Each time the protrusion 10a of the main gear 10 makes one rotation, the dependent gear 20 rotates by a predetermined angle.

[0020] A second magnet MG2 is attached to the lower surface of the slave gear 20, and the second magnet MG2 rotates as the slave gear 20 rotates. In order to detect the strength of the magnetic field generated by the second magnet MG2, a third hole is provided close to the circumference of the rotation of the second magnet MG2. The element HE3 is fixedly arranged. Therefore, a detection signal corresponding to the distance between the second magnet MG2 and the third Hall element HE3 is obtained from the third Hall element HE3. As will be described in detail later, the detection signal obtained from the third hall element HE3 is a signal representing the number of rotations of the steering shaft 4 in which direction.

Reference numeral 30 denotes a signal processing IC mounted on the substrate 8, which will be described later in detail with reference to FIG.

FIG. 3 shows an enlarged view of the relationship between the first magnet MG1 mounted on the outer peripheral surface of the steering shaft 4, the first Hall element HE1, and the second Hall element HE2. . As shown in the figure, the first magnet MG1 is separately magnetized into an S pole and an N pole. Then, since the two Hall elements HE1 and HE2 are arranged with a shift of 90 degrees, a detection signal with a phase shift of 90 degrees is obtained from the first Hall element HE1 and the second Hall element HE2.

FIG. 4 shows an electric circuit configuration of a steering angle sensor to which the present invention is applied. In this figure, DU1 is a first angle sensor unit, and includes the first Hall element HE1 and the second Hall element HE2 shown in FIGS. 2A and 2B. DU2 is a second angle sensor unit, and includes the third Hall element HE3 shown in FIGS. 2A and 2B.

First, the first angle sensor unit DU1 will be described. From the first Hall element HE1 and the second Hall element HE2, a detection signal having the same waveform whose phase is shifted by 90 degrees as shown in FIG. 5 is obtained. These two detection signals are input to the angle conversion circuit 42 via the Hall element drive & input signal amplification circuit 40. A point to be particularly noted in this angle conversion circuit 42 is that it outputs an angle detection signal S representing only a range of 0 degrees to 360 degrees based on the above two detection signals. That is, the steering shaft 4

DET

No matter how many rotations, the angle detection signal S is 0 degrees

DET represents only one 360 degree range. Therefore, it is sufficient to obtain the angle detection signal S representing the range of 0 ° to 360 ° based only on the Hall element output within the range of 0 ° to 360 ° shown on the horizontal axis of FIG. Become

DET

Therefore, accurate angle detection as shown in FIG. 6 can be performed using a known technique.

Next, the second angle sensor unit DU2 will be described. The detection signal output from the third Hall element HE3 is input to the area determination circuit 48 via the Hall element drive & input signal amplifier circuit 46. This area determination circuit 48 outputs from the third Hall element HE3. Based on the detected detection signal, the steering shaft outputs four signals that indicate the number of rotations in which direction.

FIG. 7 shows a rotation detection signal S = ± N (N = 0

ROT, 1, 2 · ·

·)). The horizontal axis in FIG. 7 indicates the rotation angle of the steering shaft 4, and the rotation angle when the steering shaft 4 rotates right is indicated by a plus sign. On the other hand, the steering shaft 4 rotates left. The rotation angle at this time is represented by a minus sign. That is, when the steering shaft 4 rotates rightward by less than 0 degree and less than 360 degrees, a rotation detection signal S representing N = 0 is output from the area determination circuit 48. Also

ROT

When the steering shaft 4 rotates rightward by less than 360 degrees and less than 720 degrees, a rotation detection signal S representing N = 1 is output from the area determination circuit 48. Similarly, stearin

ROT

When the shaft 4 rotates leftward by less than 0 degree and less than 360 degrees, a rotation detection signal S representing N = -l is output from the area determination circuit 48. In addition, the steering shaft 4

ROT

In the case where the image is rotated leftward by less than 360 ° -720 °, a rotation detection signal S representing N = −l is output from the area determination circuit 48. Hereinafter, the same applies.

ROT

[0027] The obtained angle detection signal S representing only the range of 0 degrees to 360 degrees,

DET

(2) A rotation detection signal S that indicates how much the steering shaft 4 has rotated in which direction.

ROT

Is input to the angle output circuit 44. In this angle output circuit 44, these S and S

DET ROT

Then, ± N X 360 ° + S is calculated based on the calculated result and output as an output signal S. That is,

DET OUT

Outputs the signal S (rotation angle) = ± N X 360 ° + S. Figure 8 shows the actual output

OUT DET

4 illustrates a signal s.

OUT

[0028] Note that, instead of the output signal S output from the angle output circuit 44, (ii) 0 degrees

OUT one

Whichever angle detection signal S, which represents only the 360-degree range, or the steering shaft 4

DET

Output rotation detection signal S indicating the number of rotations in each direction, or (mouth)

ROT

The form of a composite signal combining these angle detection signal S and rotation detection signal S

DET ROT

It is also possible to output it. Further, depending on the use of these output signals, the form of an analog signal or the form of a digital signal is optional. In the present embodiment, the digitalized output signal S is controlled via the AZD converter 50.

OUT

It is configured to input to the computer 50. [0029] Implementation form 2

9A and 9B are diagrams showing the second embodiment. This figure corresponds to FIGS. 2A and 2B described above.

The second embodiment has a configuration different from that of the first embodiment described above in order to obtain a rotation detection signal S indicating which direction the steering shaft 4 has rotated and how many rotations.

ROT

Yes. That is, a ball screw 60 is formed on the steering shaft 4, and a ball nut 62 that engages with the ball screw 60 and a nut rotation preventing member (not shown) are provided. A second angle sensor magnet MG2 'is fixed to one end of the ball nut 62. Therefore, the second angle sensor magnet MG2 'is moved along the rotation center axis of the steering shaft 4 by the Beaune screw 60, the ball nut 62, the nut rotation preventing member (not shown), and the powerful magnet feed mechanism. (Ie, up and down in FIG. 9B).

On the other hand, the second angle sensor Hall element HE 3 ′ is fixedly arranged on the back surface of the substrate 8 ′. With this configuration, a signal as shown in FIG. 10 is obtained from the second angle sensor Hall element HE3 '.

[0032] Other configurations are the same as those in the first embodiment, and a description thereof will not be repeated.

[0033] Implementation form 3

The signal processing IC shown in FIG. 4 includes the area determination circuit 48. The sensor output obtained from the second angle sensor unit DU2 without using the area determination circuit 48 is directly used as the rotation area instruction signal. It is also possible to output. For example, it is also possible to directly output the analog signal shown in FIG. 10 as a rotation area instruction signal, and to calculate the final rotation angle in a signal processing circuit (not shown) at the subsequent stage.

Industrial applicability

[0034] According to the present invention, no mechanical component is used for the first angle sensor that detects a highly accurate angle, so that the mechanical component does not deteriorate due to long-term use. As a result, it is possible to realize a highly accurate first angle sensor having high durability and high reliability. Furthermore, the second sensor that detects the rotation region of the shaft that has rotated many times does not need to have accurate measurement accuracy, so that various configurations can be adopted.

That is, the steering angle detection device according to the present invention is compared to a conventionally known steering angle sensor. A very small and accurate steering angle detection device can be provided.

According to the steering angle detecting device of the present invention, not only the degree of freedom of the mounting position is increased, but also

In addition, it is possible to flexibly cope with the production cost.

[0037] By implementing the present invention, it is possible to provide the uses listed below.

(1) A steering angle sensor that detects the steering angle (± 2 turns) of the electric power steering.

(2) Slot position sensor.

(3) Rotational position sensor in 2WD-4WD switch, automatic shift switch, etc. that switches gear position by motor or manual operation.

Claims

The scope of the claims

[1] In a steering angle detection device that detects a rotation angle of a shaft that rotates 360 degrees or more,

A first angle sensor having an annular magnet provided around the shaft, and a magnetic sensor for detecting a magnetic flux due to rotation of the annular magnet;

A second angle sensor that detects a range of the rotation angle of the shaft, a rotation angle of the shaft based on an output of the first angle sensor, and an output of the second angle sensor. Calculating means for calculating the angle value;

A rudder angle detecting device comprising:

[2] The steering angle detecting device according to claim 1,

The second angle sensor includes a slave gear that rotates in conjunction with each rotation of the shaft, a magnet that is fixed to the slave gear, and a magnetic detection element that detects the position of the magnet. A steering angle detecting device, comprising:

[3] The steering angle detection device according to claim 1,

The second angle sensor includes a magnet that moves in parallel with a rotation axis of the shaft in conjunction with rotation of the shaft, and a magnetic detection element that detects a position of the magnet. Rudder angle detection device.