JP2002098522A - Turning angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a space for installation which a rotating body to detect an absolute steering angle occupies around its surroundings. SOLUTION: A gear 12a is provided around a rotation shaft 12 of an encoder 15 fixed on a steering shaft S, and the gear 12a rotates a gear 16 by 1.75 revolution to one revolution of a revolving disk 13. On the gear 16 is fixed a permanent magnet 17, whose flux is detected by a magnetic sensor 20, thus generating a voltage signal of a substantially sinusoidal waveform with one cycle per one revolution of the gear 16. Then a microcomputer detects the absolute steering angle using a data table on the basis of data by combination of a code value of a code signal outputted by the encoder 15 corresponding to the absolute steering angle of the steering shaft S and a voltage of the electric signal outputted by the magnetic sensor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device for detecting an absolute steering angle of a steering wheel in a vehicle, for example.

[0002]

2. Description of the Related Art Conventionally, as this kind of rotation angle detecting device, there is a device using an incremental signal type encoder for detecting an absolute steering angle (for example, 720 ° in right steering) of a multi-turn steering wheel. As shown in FIG. 7, the incremental signal type encoder includes a rotary plate 40 fitted to the steering shaft S, and an optical sensor array 41 for detecting a slit row (not shown) formed on the rotary plate 40. I have. The encoder sequentially detects the slits in the slit row when the rotating plate 40 is rotated by the steering of the steering wheel, and outputs a pulse signal corresponding to the detected number of slits. Also, an origin signal is output from a reference slit detected when the absolute steering angle is “0”. An absolute steering angle of the steering wheel at that time is detected by counting the number of pulses of the pulse signal sequentially input according to the steering amount of the steering wheel from when the electronic control device inputs the origin signal.

However, when the absolute steering angle of the steering wheel is detected using an incremental signal type encoder, when the ignition switch of the vehicle is turned off and the electronic control unit is not energized, the absolute steering angle calculated up to that time is calculated. The corner is lost. For this reason, when the ignition switch is turned on again and the electronic control unit is energized, the encoder must be returned to the home position, and the steering angle at that time cannot be immediately detected. Therefore, when trying to detect the absolute steering angle using the incremental signal type encoder, the electronic control unit is energized even while the ignition switch is turned off, and the absolute steering angle calculated up to that time is calculated. keeping. However, since it is necessary to energize the electronic control unit even while the ignition switch is turned off, there is a disadvantage that power consumption increases.

Therefore, it is conceivable that the absolute steering angle at that time can be immediately detected, and the electronic control unit detects the absolute steering angle using an absolute signal type encoder which does not need to count pulse signals. . In order to detect the absolute steering angle of a multi-rotation steering wheel using an absolute signal type encoder, for example, as shown in FIG. 8, a first encoder 50 fitted to a steering shaft S and the first encoder 50 Encoder 50
And a second encoder 51 operatively connected to the second encoder 51. This is because the resolution is reduced when the absolute steering angle is detected by one encoder operatively connected to make one rotation with respect to the entire steering range of the steering shaft S.

[0005] The first encoder 50 has its rotating plate 52 fitted around the steering shaft S, and detects the absolute rotation angle of the first encoder 50 within a detection range of one rotation of the steering shaft S. On the other hand, the second encoder 51 is, for example,
The gear 55 fixed to the input shaft 54 meshes with the gear portion 53 provided on the second shaft 2, and the rotation of the rotating plate 52 makes one rotation of the input shaft 54. Then, the second encoder 51 detects the absolute rotation angle of the steering shaft S as two rotations as a detection range. Therefore, from the absolute steering angle in one rotation of the steering wheel detected by the first encoder 50 with a high resolution and the absolute steering angle in the entire steering range detected by the second encoder 51 with a lower resolution, the total steering angle is calculated. The absolute steering angle of the steering wheel in the range is detected with high resolution.

As described above, if the two encoders 50 and 51 of the absolute signal type are used, it is not necessary to energize the electronic control unit while the ignition switch is turned off, and power consumption does not increase.

[0007]

However, when the absolute steering angle is detected by the two encoders 50 and 51, it is necessary to decelerate the input shaft 54 of the second encoder 51 to one half of the steering shaft S. The gear 55 fixed to the input shaft 54 for deceleration becomes larger than the steering shaft S. For this reason, the space occupied by the rotation angle detecting device around the steering shaft S becomes large, and it is difficult to assemble the vehicle into the vehicle. This becomes more remarkable as the rotation speed of the steering shaft S increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to eliminate the need to hold a detected value when it is not necessary to detect the absolute rotation angle of a rotating body. Moreover, it is an object of the present invention to provide a rotation angle detection device capable of reducing the installation space occupying the periphery of the rotating body.

[0009]

According to a first aspect of the present invention, there is provided a first object to be detected which is rotated by a rotator whose absolute rotation angle is detected.
A first rotation angle detection unit that outputs a first detection signal that changes with one rotation of the detected object as one cycle; and the first detected object or the rotating body at a higher rotational speed than the first detected object. A second rotation angle detection unit that includes a second detection target that is rotated, and that outputs a second detection signal that changes with one rotation of the second detection target as one cycle; and the first detection signal and the second detection. An absolute angle detecting means for detecting an absolute rotation angle of the rotating body that makes multiple rotations from a signal is provided. Note that the first object to be detected includes not only a single object but also an object provided integrally with a rotating body.

According to such a configuration, the first detection signal that changes in one cycle of one rotation of the first object to be rotated by the rotating body, and one signal before the first object to be rotated by one rotation becomes one cycle. The absolute rotation angle of the rotator that makes multiple rotations is directly detected from the combination with the second detection signal that changes with one rotation of the rotating second detection object as one cycle. Therefore, the diameter of the second object is smaller than that of the first object.

According to a second aspect of the present invention, in the first aspect of the present invention, the first rotation angle detecting means is fitted around the rotating body and has a circumference around a rotation center axis of the rotating body. A rotating plate having a plurality of detected parts formed thereon as the first input unit, detecting the detected part according to an absolute rotational position of the rotating body, and outputting a code signal corresponding to the absolute rotational position; The gist is an absolute signal type encoder including a detection unit that generates the first detection signal.

According to such a configuration, in addition to the effect of the first aspect, the detected value of the absolute rotational position of the rotating body in one rotation is output as a code signal. Therefore, the first detection signal can be directly input to the computer and processed without A / D conversion.

According to a third aspect of the present invention, in the second aspect of the present invention, the second rotation angle detecting means includes the second rotational angle detecting means.
The gist is an analog signal type rotation angle sensor that outputs a detection signal as an analog signal.

According to such a configuration, in addition to the effect of the second aspect of the invention, the physical size of the analog signal type rotation angle sensor is smaller than that of the digital signal type rotation sensor. Therefore, the installation space occupied by the rotation angle detection device around the rotating body is further reduced.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the analog signal type rotation angle sensor includes:
A permanent magnet fixed to the second input unit, and a magnetoresistive element that outputs a sinusoidally changing analog signal based on a magnetic flux change of the permanent magnet corresponding to an absolute rotation angle of the second input unit. The gist is that

According to such a configuration, in addition to the function of the invention described in claim 3, in addition to the function of the code signal corresponding to the absolute rotation angle per rotation of the rotator and the analog signal that changes in a sine wave shape. , The absolute rotation angle of the rotating body in the detection range in which a plurality of rotations are made is detected.

According to a fifth aspect of the present invention, in the first aspect of the invention, the second rotation angle detection means outputs a sinusoidally changing angle signal as the second detection signal,
The absolute angle detecting means, when the absolute rotation angle at which the combination of the first detection signal value and the second detection signal value is the same exists in the detection range of the absolute rotation angle of the rotating body that makes multiple rotations, The gist is to specify the absolute steering angle based on the relationship between the change state of the first detection signal value and the change state of the second detection signal value.

According to this configuration, in addition to the function of the first aspect, the absolute rotation angle at which the combination of the first detection signal value and the second detection signal value is the same exists in the detection range. Even when the relationship between the change state of the first detection signal value and the change state of the second detection signal value is different, the absolute rotation angle can be specified. That is, when the first detection signal value increases and becomes the signal value, whether the second detection signal value increases and becomes the corresponding signal value, or decreases and becomes the corresponding signal value, An absolute steering angle in which the combination of both signal values is the same can be determined. Further, when the first detection signal value decreases and becomes the signal value, whether the second detection signal value increases to the corresponding signal value, or decreases and becomes the corresponding signal value, An absolute steering angle in which the combination of both signal values is the same can be determined.
Therefore, the absolute rotation angle can be detected by using the second rotation angle detection unit that outputs a signal that changes in a sine wave shape as the second detection signal.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a steering angle detecting device for detecting an absolute steering angle of a steering wheel in a vehicle will be described with reference to FIGS.

As shown in FIGS. 1A and 1B, a steering angle detecting device 10 as a rotation angle detecting device is mounted on a steering shaft S as a rotating body. The steering angle detecting device 10 includes a housing 11 fixed to a structure around a steering shaft S, and a rotating shaft 12 is rotatably supported on the housing 11. The rotating shaft portion 12 is fixed in a state of being fitted around the steering shaft S, and rotates together with the steering shaft S.

The housing 11 accommodates a rotating plate 13 as a first object to be detected which is supported on the outer peripheral surface of the rotating shaft 12 and rotates together with the rotating shaft 12. The rotating plate 13 is provided on a plurality of circumferences centered on the center axis thereof.
3, a plurality of annular slit rows 13 as a detected part for generating an absolute signal code for detecting the absolute rotation angle of, for example, a pure binary code or a gray code.
a are respectively formed.

In the housing 11, an optical sensor array 14 is provided as a detecting unit for generating a code signal from each of the annular slit rows 13a of the rotary plate 13. Each of the optical sensors 14a of the optical sensor array 14 is a known one and includes, for example, an LED and a photodiode. The rotary shaft 12, the rotary plate 13, and the optical sensor array 14 constitute an absolute signal type encoder 15 as first rotation angle detecting means. In addition, a gear portion 12 a having the steering shaft S as a rotation shaft is formed on an outer peripheral portion of the rotation shaft portion 12.

A gear body 16 as a second object to be detected is rotatably supported in the housing 11. The gear body 16 is meshed with the gear portion 12a of the rotating shaft portion 12. The gear body 16 is formed with a gear ratio of 1.75 rotations per rotation of the rotary shaft 12.

A permanent magnet 17 is fixed to the center of the gear body 16. The permanent magnet 17 is provided so as to generate a magnetic flux in a predetermined radial direction in the gear body 16. Therefore, when the gear body 16 makes one rotation, the permanent magnet 1
7 also rotates 360 °.

A circuit board 18 is fixed in the housing 11 at a position facing the gear body 16. Circuit board 18
Above, a magnetoresistive element 19 is provided at a position facing the permanent magnet 17.
Is provided. The magnetoresistive element 19 is of a differential output type, and detects the magnetic flux generated by the permanent magnet 17 to
6 outputs a voltage signal having a magnitude corresponding to the rotation angle. An amplifier (not shown) for amplifying a voltage signal output from the magnetoresistive element 19 is formed on the circuit board 18. A second rotation angle detecting means and a magnetic sensor 20 as an analog signal rotation angle sensor are formed by the magnetoresistive element 19 and the amplifier.

The circuit board 2 is provided in the housing 11.
1 is provided. On this circuit board 21, a microcomputer (hereinafter, referred to as a computer) 22 as an absolute angle detecting means is provided.

Next, the electrical configuration of the steering angle detecting device 10 will be described. As shown in FIG. 3, when the steering wheel is steered to the right from the straight traveling state, the encoder 15 controls the steering angle range from the absolute steering angle “0 °” to “360 °” and the absolute steering angle “360 °”. "To" 720
A code signal SC whose value is monotonically increased from "C0" to "Cmax" in the steering angle range up to "°" is output. Similarly, when the steering wheel is steered to the left from the straight running state, the encoder 15 sets the steering angle range from the absolute steering angle “0 °” to “−360 °” and “−360 °”.
With a steering angle range from 360 ° to -720 °,
A code signal SC whose value is monotonously reduced from "Cmax" to "C0" is output.

When the steering wheel is steered to the right from the straight running state, the magnetic sensor 20 changes the absolute steering angle from "0 °" to "205.6 ° (= 360 ° / 1.7).
5), a voltage signal SV that changes in a sine wave form having one cycle in the steering angle range up to the steering angle range from “0 °” to “3”.
Voltage signal S having 1.75 cycles in a steering angle range of “60 °”
Output V. Similarly, when the steering wheel is steered to the left from the straight running state, the magnetic sensor 20 has a sine wave shape having one cycle in the steering angle range from the absolute steering angle “0 °” to “−205.6 °”. Changing voltage signal SV,
That is, a voltage signal SV having 1.75 cycles in the steering angle range from the absolute steering angle “0 °” to “−360 °” is output. In the present embodiment, the code signal SC is a first detection signal,
The voltage signal SV is the second detection signal.

As shown in FIG. 2, each optical sensor 14a of the optical sensor array 14 is directly connected to the input side of the computer 22. On the input side, a magnetic sensor 2
0 is connected via the A / D converter 23. The computer 22 reads the code signal output from the optical sensor array 14 and the voltage value output from the magnetic sensor 20 via the A / D converter 23 as needed.

The computer 22 is energized only when the ignition switch of the vehicle is turned on. When the computer 22 is energized, the CPU 24 executes a control program stored in the ROM 25. By executing the control program, the CPU 24 inputs the code value of the code signal SC output from the encoder 15 and the voltage value of the voltage signal SV output from the magnetic sensor 20 via the A / D converter 23 as needed. Then, the CPU 24 detects the absolute rotation angle of the rotary shaft 12, that is, the absolute steering angle of the steering shaft S from the code value and the voltage value as needed. In this embodiment, the steering wheel is steered right from the straight running state at the absolute steering angle of “0 °” to two rotations of “720 ° absolute steering angle”.
°) and the steering range up to an absolute steering angle “−720 °” of left steering from a straight running state to two rotations. However,
The right steering does not include the absolute steering angle “720 °”, and the left steering does not include the absolute steering angle “−720 °”. this is,
This is because the absolute steering angles “−720 °” and “720 °” cannot be distinguished. In this specification,
For convenience of explanation, the absolute steering angle at the time of right steering is expressed as a positive value, and the absolute steering angle at the time of left steering is expressed as a negative value.

The CPU 24 detects an absolute steering angle using a data table stored in the ROM 25. As shown in FIG. 4, the data table is a combination of a code value detected by the encoder 15 and a voltage value output by the magnetic sensor 20 when the code value is output within the detection range of the absolute steering angle. In addition, the absolute steering angle corresponds to the combination of these two data. Therefore, the CPU 24 detects the absolute steering angle with the resolution of the encoder 15. It should be noted that the data table of FIG. 4 shows only some combination data of the code value and the voltage value and the absolute steering angle.

In the data table, only a plurality of specific code values C1 to C13 shown in FIG.
A change state of the voltage value when the code value increases or decreases to the code value is stored. More specifically, when the code value increases with steering wheel operation and reaches specific code values C1 to C13, the voltage value increases to a corresponding voltage value, or decreases to a corresponding voltage value. Whether it becomes a voltage value is stored. Similarly, when the code value decreases to a specific code value C1 to C13, whether the voltage value decreases to the corresponding voltage value or increases to the corresponding voltage value is stored. ing. The reason is as follows.

As shown in FIG. 3, the code value output from the encoder 15 repeats a monotonically increasing change in a cycle of the relative steering angle of 360 °, while the voltage value output from the magnetic sensor 20 indicates the relative steering angle. It changes sinusoidally with a period of 205.6 °. Thus, there are a plurality of two points where the combination of the code value and the voltage value match despite the difference in the value of the absolute steering angle.

For example, as shown in FIG. 4, in the steering angle range from the absolute steering angle “0 °” to “360 °”, each absolute steering angle value 102.8 (=) when the voltage value becomes “0”.
25.7 * 4), 205.6 ° (= 25.7 ° * 8),
The code values for 308.4 ° (= 25.7 ° * 12) are C4, C8, and C12, respectively. On the other hand, in the steering angle range from the absolute steering angle “−720 °” to “−360 °”, each absolute steering angle value (−10) when the voltage value becomes “0”.
720 + 102.8) °, (−720 + 205.6)
The code value for °, (−720 + 308.4) ° is
They are C4, C8, and C12, respectively. That is, as shown in FIG. 3, the voltage values for the absolute steering angle 102.8 ° shown at point A and the absolute steering angle (−720 + 102.8) ° shown at point B are both “0”, Both values are C
It becomes 4.

Further, from the absolute steering angle "360 °" to "72"
In the steering angle range of “0 °”, each absolute steering angle value (360 + 51.4) ° (= 25.5) when the voltage value becomes “0”.
7 ° * 2), (360 + 154.2) ° (= 25.7 °)
* 6), (360 + 257.0) ° (= 25.7 ° * 1)
Code values for 0) are C2, C6, and C10, respectively. On the other hand, in the steering angle range from the absolute steering angle “−360 °” to “0 °”, the absolute steering angle values (−360 + 51.4) ° and (−360 + 1) when the voltage value becomes “0”.
The code values for 54.2) ° and (−360 + 257.0) ° are C2, C6, and C10, respectively.

Further, from the absolute steering angle “0 °” to “360”
°), the absolute steering angle values 25.7 ° and 231.3 ° (= 2) when the voltage value becomes “V1”.
The code values for 5.7 ° * 9) are C1 and C9, respectively.
And On the other hand, from the absolute steering angle “−360 °” to “0 °”
, The absolute steering angle values (−360 + 25.7) ° and (−360) when the voltage value becomes “V1”.
+231.3) ° is C1,
C9. That is, as shown in FIG. 3, the absolute steering angle 25.7 ° indicated by the point C and the absolute steering angle (−360
+25.7) ° are both “V1”, and the code values are also both C1.

Similarly, when the voltage value is "-V1", each absolute steering angle value is 128.5 ° (= 25.7 * 5), 33
Assuming that the code values for 4.1 ° (= 25.7 ° * 13) are C5 and C13, the absolute steering angle values (−720 + 128.5) ° when the voltage value is “−V1”,
The code values for (−720 + 334.1) ° are C5 and C13, respectively.

The absolute steering angle "0 °" to "360"
°), the absolute steering angle value 77.1 ° (= 25.7 ° * 3) when the voltage value becomes “V1”,
The code values for 282.7 ° (= 25.7 ° * 11) are C3 and C11, respectively. On the other hand, the absolute steering angle "3
In the steering angle range from “60 °” to “720 °”, the absolute steering angle value (360 + 7) when the voltage value becomes “V1”
The code values for 7.1) ° and (360 + 282.7) ° are C3 and C11, respectively. Similarly, each absolute steering angle value 179.9 ° when the voltage value becomes “−V1”
Assuming that the code value for (= 25.7 ° * 7) is C7, the code value for each absolute steering angle value (360 + 179.9) ° when the voltage value is “−V1” is C7.

As described above, the combination of the code value and the voltage value at the time of detection is the same in the steering angle range from the absolute steering angle "-720 °" to "720 °" which is the detection range.
There are a plurality of absolute steering angles. However, even if the combination of the code value and the voltage value is the same, the combination of the change state of the code value and the change state of the voltage value is different. That is, at two absolute steering angle values having the same combination of the code value and the voltage value, when the code value increases and reaches the specific code value, the voltage value decreases at one absolute steering angle. At the other absolute steering angle, the voltage value increases and becomes the voltage value.

For example, when the absolute steering angles are “102.8 °” and “(−720 + 102.8) °”, both the code value is “C4” and the voltage values are both “0”.
However, when the absolute steering angle is “102.8 °”, the voltage value decreases to “0” when the code value increases to “C4”, while the absolute steering angle becomes “(−720 + 10”.
2.8) ° ”, the code value increases to“ C4 ”
When it becomes, the voltage value increases to “0”. this is,
This holds true for all combinations of absolute steering angles where the combination of the code value and the voltage value is the same.

Therefore, the code value corresponding to the absolute steering angle to be detected is determined by the specific values C1, C2,.
When it is 3, the actual absolute steering angle can be specified by determining the voltage gradient of the voltage value with respect to the change state of the code value at that time. For this reason, the data table contains a code value C corresponding to each absolute steering angle.
Data indicating the change state of the voltage value with respect to the change state when the code value becomes the code value is stored for each of 1, C2, ..., C13.

That is, as shown in FIG.
With respect to 1, C2,..., C13, when the code value increases and reaches the code value, when the voltage gradient is positive, the change state of the voltage value is stored as “+”, and when the voltage gradient is negative. At some point, the change state of the voltage value is stored as "-". Similarly, each code value C1, C2,
.., C13, when the code value decreases and becomes the code value, the change state of the voltage value is stored as “−” when the voltage gradient is positive, and the voltage value is stored when the voltage gradient is negative. Is stored as “+”.

The CPU 24 detects the absolute steering angle using the data table as described below. (When the read code value is not a specific value) CPU2
4 is a code value output by the encoder 15 according to the actual absolute steering angle of the steering wheel at that time;
The voltage value output from the magnetic sensor 20 is read. When the code value is not the specific code values C1 to C13, the CPU 24 checks the combination of the code value and the voltage value with each combination data of the code value and the voltage value in the data table. Then, the absolute steering angle value corresponding to the combination data of the matched code value and voltage value is output as a detection value. Therefore, when the actual absolute steering angle of the steering wheel is not a plurality of specific absolute steering angles at which a specific code value is output, even immediately after the ignition switch of the vehicle is turned on and the computer 22 is energized, Further, even if the steering wheel is not steered, the absolute steering angle at that time is detected.

(When the read code value is a specific value) The CPU 24 determines that the first detected code value upon activation of the computer 22 is the specific code values C1, C
If it is any of 2, C13, the absolute steering angle is not detected. This is because the change state of the code value cannot be determined, and the change state of the voltage value cannot be determined, so that the actual absolute steering angle cannot be specified. Therefore, when the computer 22 is started, when the actual absolute steering angle of the steering wheel is a plurality of specific absolute steering angles and the steering wheel is not steered, the absolute steering angle is not detected.

In this state, the steering wheel is steered, and the detected code values are changed to specific code values C1 to C1.
When it is no longer 3, the CPU 24 detects the absolute steering angle from the combination of the newly detected code value and voltage value using the data table. Therefore, computer 2
When the steering wheel is steered, even if the actual absolute steering angle of the steering wheel is a plurality of specific absolute steering angles when the steering wheel 2 is activated, the absolute steering angle at that time is detected.

On the other hand, when the code value and the voltage value to be detected change with the steering of the steering wheel, the CPU 24 determines that the code value finally detected by stopping the steering of the steering wheel is the specific code value. Is detected, the absolute steering angle at that time is detected as follows. The CPU 24 regards the absolute steering angle closest to the absolute steering angle detected from the combination of the code value and the voltage value detected before detecting the specific code value finally detected as the actual absolute steering angle at that time. . Then, it is determined whether or not the change state of the voltage value with respect to the change state of the code value corresponding to the absolute steering angle matches the actual change state.

When the change state of the voltage value with respect to the change state of the code value matches the actual change state, the CPU 24 outputs a value regarded as the actual absolute steering angle as a detection value.

On the other hand, when the CPU 24 does not match the actual change state, the CPU 24 determines whether the absolute steering corresponding to another combination of the code value and the voltage value that matches the finally detected combination of the code value and the voltage value. The angle is output as the actual detection value.

Therefore, when the steering wheel is steered, the final absolute steering angle is detected even when the final absolute steering angle becomes one of a plurality of specific absolute steering angles.

According to the embodiment described above, the following effects can be obtained. (1) The computer 22 collates a combination of a code value output by the encoder 15 and a voltage value output by the magnetic sensor 20 in accordance with the absolute steering angle of the steering wheel with a data table to determine the absolute steering angle. At this time, the gear body 16 that rotates at a higher rotational speed than the encoder 15
May be smaller in outer diameter than the gear portion 12a of the rotating shaft portion 12. Therefore, when it is not necessary to detect the absolute steering angle of the steering wheel, the computer 22 does not need to hold the detected value, and the installation space occupying the periphery of the steering shaft S can be reduced. As a result, the steering shaft S
Can be more easily assembled into the vehicle interior where the is disposed.

(2) The absolute rotation angle per rotation of the steering shaft S is detected by an absolute signal type encoder in which the rotary plate 13 is fitted on the steering shaft S. Therefore, since the detected value of the absolute rotation angle is output as a code value, it can be directly input to the computer 22 for processing without A / D conversion.

(3) Permanent magnet 1 fixed to gear body 16
The sine wave analog signal is obtained by detecting the magnetic flux of No. 7 with the magnetoresistive element 19. Then, the absolute steering angle is obtained from the voltage gradient in addition to the combination of the code value and the voltage value. Therefore, the installation space occupied by the steering angle detecting device around the steering shaft S is further reduced as compared with the case where another encoder is provided separately from the encoder 15.

The embodiment is not limited to the above embodiment, but may be modified as follows. In the above embodiment, the change period of the voltage signal of the magnetic sensor 20 is set so that the absolute steering angle at which the combination data of the code value and the voltage value becomes the same in the detection range does not exist, and the code value and the voltage value are changed. The absolute steering angle may be detected only from the combination data. For example, if the change period of the voltage value is set in the range from the steering angle of 241 ° to 359 °, the absolute steering angle at which the combination data of the code value and the voltage value becomes the same in the detection range of −720 ° to 720 ° is obtained. Can be absent.

In the above embodiment, the analog signal type rotational displacement sensor is not limited to the magnetic sensor 20, but may be a potentiometer, a rotary differential transformer, or the like. In this case, the input shaft of the potentiometer is operatively connected to the encoder 15 so that the input shaft rotates at less than one rotation per rotation of the rotary plate 13. Then, as shown in FIG. 5, the change period of the voltage value output by the potentiometer is set to, for example, the steering angle 360
By making it slightly smaller than °, the voltage value corresponding to the code value is made different in each detection range divided for each rotation of the encoder 15. In this case, encoder 1
Since there is no absolute steering angle at which the combination data of the code value of 5 and the voltage value of the potentiometer are the same, the absolute steering angle can be detected only by the combination of the code value and the voltage value. Even with this configuration, it is possible to further reduce the installation space occupied by the steering angle detection device around the steering shaft S as compared with a case where an encoder other than the encoder 15 is provided as the second rotation angle detection means. it can.

In the above embodiment, the first rotation angle detecting means is not limited to the absolute signal type encoder 15 but may be an analog signal type rotation angle sensor such as a potentiometer or a rotary differential transformer. In this case, the gear portion provided on the outer peripheral surface of the steering shaft S is meshed with a gear having the same number of teeth fixed to, for example, an input shaft of a potentiometer, and further, the gear body 16 of the magnetic sensor 20 is meshed with this gear. I just need. In this configuration, the absolute steering angle is detected from the combination data of the voltage value output by the first rotation angle detection means and the voltage value output by the magnetic sensor 20. Even with such a configuration, the installation space occupied by the steering angle detection device around the steering shaft S can be reduced.

In the above embodiment, the absolute signal type encoder 15 is not limited to the optical type in which the code value is generated by the annular slit array 13 a provided on the rotating plate 13 and the optical sensor array 14, but may be a magnetic type or a laser type. There may be.

In the above embodiment, the absolute rotation angles when the rotating body rotates clockwise and counterclockwise from the reference position are detected. For example, as shown in FIG. The absolute rotation angle when rotating in only one direction from the position may be detected.

In the above embodiment, the rotating plate 13 as the first object to be detected is externally fitted to the steering shaft S as the rotating body, but the steering shaft S is provided with a gear having the same number of teeth as the gear portion 12a. The steering angle detecting device may be configured to fit the gear and mesh with the gear portion 12a. Also in the case of this configuration, the installation space occupying the periphery of the steering shaft S can be reduced as compared with the case where two encoders 50 and 51 are used as in the related art.

In the above embodiment, the present invention is applied to a steering angle detecting device for detecting an absolute steering angle of a steering wheel. However, for example, an absolute rotation angle for detecting an absolute rotation angle of a rotating shaft in a machine tool having a rotating shaft is also used. The detection device may be implemented.

[0060]

As described in detail above, claims to claim 5 are provided.
According to the invention described in (1), it is not necessary to hold the detection value when it is not necessary to detect the absolute rotation angle of the rotating body, and it is possible to reduce the installation space occupying the periphery of the rotating body.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view showing a steering angle detecting device, and FIG. 1B is a schematic side sectional view thereof.

FIG. 2 is an electric block diagram.

FIG. 3 is a graph showing output characteristics of an encoder and a magnetic sensor with respect to an absolute steering angle.

FIG. 4 is an explanatory diagram of a data table.

FIG. 5 is a graph showing output characteristics of an encoder and a potentiometer according to another embodiment.

FIG. 6 is a graph showing output characteristics of an encoder and a magnetic sensor according to another embodiment.

FIG. 7 is a schematic perspective view of a conventional rotation angle detection device.

FIG. 8 is a schematic plan view of the rotation angle detection device.

[Explanation of symbols]

10 ... steering angle detecting device as rotation angle detecting device, 13
... A rotating plate as a first object to be detected, 13a an array of slits as an object to be detected, 14 an optical sensor array as a detecting unit, 15 an absolute signal type encoder as a first rotation angle detecting means, 16 an second. Gear body as an object to be detected, 17: permanent magnet, 19: magnetoresistive element, 20: second
A magnetic sensor as a rotation angle detecting means and an analog signal type rotation angle sensor; a microcomputer as an absolute angle detecting means; a steering shaft as a rotating body; a SC; a code signal as a first detection signal; 2 Voltage signal as detection signal.

Continued on the front page (72) Inventor Yasuhiko Nimura 3-260 Toyota, Oguchi-machi, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Works, Ltd. (72) Inventor Shigeji Ito 3-260 Toyota, Oguchi-machi, Nishi-gun, Awa F-term in Tokai Rika Electric Works (reference)

Claims (5)

[Claims] A first detection object that is rotated by a rotator whose absolute rotation angle is detected, and outputs a first detection signal that changes with one rotation of the first detection object as one cycle.
A rotation angle detection unit, and a second object to be rotated by the first object or the rotating object at a higher rotation speed than the first object to detect. A second rotation angle detection unit that outputs a second detection signal that changes as one cycle, and an absolute angle detection unit that detects an absolute rotation angle of the rotating body that makes multiple rotations from the first detection signal and the second detection signal. A rotation angle detection device comprising: 2. The method according to claim 1, wherein the first rotation angle detecting means includes a rotating plate, which is externally fitted to the rotating body and has a plurality of detected parts formed on a circumference around a rotation center axis of the rotating body. An absolute signal type comprising: an input unit; and a detection unit that detects the detected portion according to an absolute rotation position of the rotating body and generates a code signal corresponding to the absolute rotation position as the first detection signal. The rotation angle detection device according to claim 1, which is an encoder. 3. The rotation angle detection device according to claim 2, wherein the second rotation angle detection means is an analog signal type rotation angle sensor that outputs the second detection signal as an analog signal. 4. An analog signal type rotation angle sensor according to claim 1, wherein said analog signal type rotation angle sensor has a sine wave shape based on a permanent magnet fixed to said second input portion and a magnetic flux change of said permanent magnet corresponding to an absolute rotation angle of said second input portion. 4. The rotation angle detecting device according to claim 3, further comprising: a magnetoresistive element that outputs an analog signal that changes in a direction. 5. The second rotation angle detection means outputs a sinusoidally changing angle signal as the second detection signal, and the absolute angle detection means detects an absolute rotation angle of the rotating body that makes multiple rotations. When there is an absolute rotation angle in the range where the combination of the first detection signal value and the second detection signal value is the same, the change state of the first detection signal value and the change state of the second detection signal value at that time 2. The rotation angle detecting device according to claim 1, wherein the absolute steering angle is specified based on the relationship with the rotation angle.