JPH11287634A - Steering sensor for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an accurate absolute steering angle at early stages. SOLUTION: The three sets of photointerrupters 8, 9, 10 of a first detection device 6 output signals showing respectively the amount and direction of rotation of a steering wheel and a reference position during one rotation, in accordance with the rotation of a first rotor 1 which rotates integrally with the steering wheel. A worm wheel 12 serving as a second rotor reduces the speed of rotation of the steering wheel via a gear mechanism 13 and rotates within a range of less than the one rotation. A second detection device 17 comprises a magnet 14 provided on one side of the worm wheel 12 and a magnetoresistance element 16 opposite thereto and outputs signals showing the rotary position and the absolute steering angle of the worm wheel 12. The accurate absolute steering angle can be detected at early stages in accordance with the detection signals of the first and second detection devices 6, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle steering sensor used for detecting an absolute steering angle of a steering wheel.

[0002]

In recent years, in automobiles, a steering sensor has been used in a vehicle stabilit (VSC).
ycontroll) is used as a representative vehicle control system and is considered as an important signal. As a conventional steering sensor, one having the following configuration is generally used.

[0003] That is, the steering sensor is composed of a slit plate provided with a large number of slits, which is provided so as to rotate integrally with the steering wheel, and three sets of photo interrupters provided in a fixed state on the steering column. . Each photo interrupter has a configuration in which a light emitting diode and a light receiving element are opposed to each other, and a slit plate inserted between the light emitting diode and the light receiving element rotates to change between a light shielding state and a light transmitting state. A signal is output from each light receiving element based on the signal.

The first and second photo-interrupters among the three photo-interrupters are for detecting the rotation amount and the rotation direction of the steering wheel (slit plate), and the remaining third photo-interrupters are: Neutral position during one rotation of the steering wheel (reference position)
These output signals are output to the control device of the vehicle.

The range in which the steering wheel can be rotated is not limited to one rotation (360 degrees), but is, for example, two rotations to the left (720 degrees) and two rotations to the right (720 degrees) around the neutral position. 720 degrees)
± 720 degrees. However, even if there is a neutral position signal from the third photo interrupter among the output signals from the steering sensors (first to third photo interrupters), it is not known how many rotations the signal is. Therefore, an accurate absolute steering angle of the steering wheel cannot be detected only by the output signal from the steering sensor.

Therefore, conventionally, the accurate absolute steering angle (the angle based on the true neutral position) is shown in FIG.
Detection is performed according to the flow shown in FIG. That is, in a state immediately after the ignition switch is turned on, the absolute steering angle cannot be detected. The car runs,
When a neutral edge (see X and X positions in FIG. 4) is detected in the third photo interrupter, the control device outputs an output signal from the third photo interrupter,
Based on the output signals from the first and second photointerrupters, the rotation amount and the rotation direction (relative steering angle) from the neutral position can be detected. However, it is not known how many rotations the neutral position is. Then, the vehicle further travels, and detects an accurate absolute steering angle based on the output signals of the first to third photointerrupters and the detection signals of the vehicle speed sensor and the yaw rate sensor. And

However, in the above-described conventional configuration, it is necessary to travel to some extent from when the ignition switch is turned on to when an accurate absolute steering angle is detected, and the VSC cannot be on standby until then. Therefore, there is a demand for a steering sensor that can detect an accurate absolute steering angle as soon as possible after turning on an ignition switch.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicular steering sensor capable of detecting an accurate absolute steering angle at an early stage.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first rotating body which is integrally rotated with a steering wheel capable of rotating one or more rotations. First detection means for outputting a signal indicating the amount and direction of rotation of the steering wheel based on the rotation of the first rotating body, and a signal indicating a reference position during one rotation of the steering wheel; The second steering wheel is provided so as to rotate the steering wheel in a range of less than one rotation via a speed reduction means in response to the maximum amount of rotation in the maximum range.
And a second detector for outputting a signal indicating the absolute steering angle of the steering wheel based on the rotational position of the second rotator.

In the above configuration, when the steering wheel is rotated, the first rotating body is rotated integrally with the steering wheel, and the second rotating body is rotated in a decelerated state. Of these, based on the rotation of the first rotating body, a signal indicating the amount and direction of rotation of the steering wheel and a signal indicating the reference position during one rotation of the steering wheel are output from the first detection means. Further, a signal indicating the absolute steering angle of the steering wheel is output from the second detecting means based on the rotational position of the second rotating body.

[0011] Here, the second rotating body is rotated by a maximum amount within a range in which the steering wheel can be operated to rotate.
Since the rotation is performed in a range of less than the rotation, the absolute steering angle of the steering wheel can be estimated based on the detection of the rotation position of the second rotating body. However, this absolute steering angle is not always accurate because it includes an error due to the second detection means and a rattling error of the deceleration means, but a rough absolute steering angle can be estimated. . Therefore, the output signal of this second detection means (roughly the absolute steering angle) and the first output signal
Based on the output signal (relative steering angle) of the detecting means, an accurate absolute steering angle can be detected at an early stage.

In this case, it is preferable that the first rotating body has a plurality of reference position signal generating means indicating a reference position in one rotation. If the reference position signal generating means indicating the reference position is only one position during one rotation, a signal indicating the reference position cannot be obtained unless the first rotating body (steering wheel) rotates at most one rotation at a maximum. However, as described above, the reference position signal generation means indicating the reference position is 1
When there are a plurality of rotations, a signal indicating the reference position can be obtained with a small rotation amount of the first rotating body (steering wheel), so that an accurate absolute steering angle can be detected even earlier. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, FIG. 1 is a bottom view of the steering sensor portion viewed from below, and FIG. 2 is a side view of the steering sensor portion viewed from the side. 1 and 2, the first rotating body 1 and the driving gear 2 are mounted on the steering shaft 3 so as to rotate integrally with the steering shaft 3 in a state of being vertically overlapped. It is configured to rotate integrally with a steering wheel (not shown) attached to the steering shaft 3. In this case, the range in which the steering wheel can be rotated is two rotations to the left (720 degrees) and two rotations to the right (720 degrees) around the neutral position.
± 720 degrees. A gear portion 2 a is formed on the outer peripheral portion of the drive gear 2.

As shown in FIG. 3, a large number of signal slits 4 are arranged in a circular arrangement centered on the center of the steering shaft 3 at a position from the outer peripheral portion of the first rotating body 1 as shown in FIG.
In addition, a reference signal notch 5 that forms reference position signal generating means that indicates a reference position is formed at one position outside the signal slit 4 and is formed at equal intervals. In this case, the reference signal notch 5 is formed in a range of 55 degrees.

The first rotating body 1 corresponds to the first
The first detecting device 6 constituting the detecting means is provided in a fixed state. The first detecting device 6 includes a mounting base 7
First, second, and third photointerrupters 8, 9,
10 is incorporated. Each of the first to third photointerrupters 8, 9, and 10 has a configuration in which a light emitting diode and a light receiving element are opposed to each other.

The first and second photo interrupters 8 and 9 are arranged such that the light emitting diode and the light receiving element sandwich a portion corresponding to the rotation locus of the signal slit 4 in the first rotating body 1 from above and below. Low level when it corresponds to the signal slit 4 (in the light transmitting state),
When it does not correspond to the signal slit 4 (when light is blocked)
Output the high-level detection signals Sa and Sb (see FIG. 4). In this case, the arrangement pitch of the signal slits 4 and the first
The arrangement of the second photointerrupters 8 and 9 is set so that the resolution by the detection signals Sa and Sb is 1.125 degrees and the phase is shifted by 1/4 cycle.

Further, the third photo interrupter 10
When the light emitting diode and the light receiving element are arranged so as to sandwich a portion corresponding to the rotation locus of the reference signal notch 5 in the first rotating body 1 from above and below, and correspond to the reference signal notch 5 (light transmission). The detection signal Sc (see FIG. 4) at a low level is output when the signal does not correspond to the notch 5 for the reference signal (when in the light-shielded state).

On the other hand, the gear portion 2a of the drive gear 2 has
The gear portion 11a of the relay gear 11 meshes. A worm 11b is provided below the relay gear 11 so as to rotate integrally therewith, and a worm wheel 12 constituting a second rotating body meshes with the worm 11b. In this case, the rotation center axis of the relay gear 11 and the steering shaft 3 are in a parallel state, but the rotation center axis 12a of the worm wheel 12 is orthogonal to the rotation center axis of the relay gear 11 and the steering shaft 3.

Here, the driving gear 2, the relay gear 11,
The worm wheel 12 constitutes a gear mechanism 13 which constitutes a speed reducing means for reducing the rotation of the steering wheel and transmitting the rotation to the worm wheel 12. In this case, the worm wheel 12 rotates less than one rotation, in this case, 100 degrees (± 50 degrees) in response to the steering wheel being rotated by the maximum amount (± 720 degrees) within the range in which the rotation operation is possible.
(Degree). Therefore, as the gear portion 12a of the worm wheel 12,
It is formed only in a range slightly larger than 100 degrees.

At the center of one surface (the upper surface in FIG. 1) of the worm wheel 12, a magnet 14 is mounted so as to rotate integrally with the worm wheel 12.
Then, one surface of the worm wheel 12 (the magnet 14
A magnetoresistive element 16 is attached to a printed circuit board 15 provided in a fixed state so as to face the surface on which the magnet 14 is attached. In this case, the magnet 14 and the magnetoresistive element 16
The second detecting device 17 constituting the second detecting means is constituted. The magnetoresistive element 16 has a characteristic that the resistance value changes based on the change in the direction of the magnetic field by the magnet 14 according to the rotational position of the worm wheel 12,
The detection signal Sd as shown in FIG. 5 is output.

The detection signals Sa, from the first to third photointerrupters 8 to 10 in the first detector 16 are
The detection signals Sb, Sc, and the detection signal Sd from the magnetoresistive element 16 in the second detection device 17 are sent to the calculation unit 18 as shown in FIG. The arithmetic unit 18 includes a microcomputer, and detects the absolute steering angle of the steering wheel based on the signals Sa, Sb, Sc, and Sd, as described later.
Send to system 19.

Next, the operation of the above configuration will be described with reference to FIGS. FIG. 7 is a flow chart when the absolute steering angle is detected by the calculation unit 18, and FIG. 8 is an explanatory diagram for explaining a flow when the absolute steering angle is detected.

When the ignition switch is turned on (step S1), the arithmetic unit 18 calculates a value based on a detection signal Sd from the magnetoresistive element 16 in the second detection device 17 and outputs the result.
An absolute steering angle A of the steering wheel is obtained by calculation (step S2), and the absolute steering angle A is set as an output value (step S3). This output value is converted to a serial signal and transmitted to the VSC system 19.
Here, the absolute steering angle A obtained based on the detection signal Sd
Are errors due to the characteristics of the magnetoresistive element 16 and the gear mechanism 13
Because of this, it is possible to estimate a rough absolute steering angle (how many turns, an approximate angle), if not necessarily accurately, even if it is not accurate.

When the steering wheel is operated to rotate as the vehicle travels, the first rotating body 1 is rotated integrally with the steering shaft 3. Based on the rotation of the first rotating body 1, detection signals Sa and Sb are output from the first and second photo-interrupters 8 and 9 in the first detection device 6, and the calculation unit 18 outputs the detection signals Sa and Sb. , Sb, the relative steering angle α (rotation amount and rotation direction) of the steering wheel is detected (step S4), and this relative steering angle α is set as an output value in addition to the absolute steering angle A (step S5). .

In this case, the rotation amount (rotation angle) can be detected by counting the number of pulses of the detection signals Sa and Sb, and the rotation direction is detected based on the phase difference between the detection signals Sa and Sb. be able to.

When a neutral edge X (see FIG. 4) is detected at a certain timing based on the detection signal Sc of the third photo interrupter 10 (step S6),
It can be determined that the position is the neutral position within one rotation.

Based on the absolute steering angle A, the relative steering angle α, and the neutral edge X obtained as described above, an accurate absolute steering angle B is detected and determined (step S7).
This is set as an output value (step S8). This output value is converted to a serial signal and
9 is transmitted. Thereafter, the relative steering angle α is detected based on the detection signals Sa, Sb, Sc from the first detection device 6, and the absolute steering angle B and the relative steering angle α are added and set as an output value (step S9, 10). The VSC system 19 calculates the absolute steering angle B + thus obtained.
The VSC is controlled based on α.

According to the above-described embodiment, the following effects can be obtained. That is, when the ignition switch is turned on, the absolute steering angle A can be detected based on the detection signal Sd of the second detection device 17. The absolute steering angle A is not accurate because it includes an error due to the characteristics of the magnetoresistive element 16 and a rattling error in the gear mechanism 13, but it is not possible to detect the absolute steering angle as a rough absolute steering angle. it can. Therefore, based on the approximate absolute steering angle A based on the detection signal Sd of the second detection device 17 and the detection signals Sa, Sb, Sc of the first detection device 6 similar to the conventional one, accurate absolute steering is performed. The angle B can be detected early.

Further, since the calculation section 18 can detect the accurate absolute steering angle B only with the detection signals Sa, Sb, Sc, and Sd from the steering sensor, the accurate absolute steering angle B can be obtained by the vehicle speed sensor and the vehicle speed sensor. There is also an advantage that the detection can be performed without using the detection signal of the yaw rate sensor.

FIG. 9 shows a second embodiment of the present invention. The second embodiment differs from the first embodiment in the following points. That is, in the first rotating body 1,
The reference signal notches 20 constituting the reference position signal generating means indicating the reference position are formed at four locations at equal intervals. In this case, the angle range of each reference signal notch 20 is set to 50 degrees, and the angle range between each reference signal notch 20 is set to 40 degrees. In this case, the detection error of the detection signal Sd is ± 4.
It can be within 0 degrees.

Here, in the case of the first embodiment, the reference signal notch 5 (the angle range is 55
(Degree) is only one position during one rotation, and if the first rotating body 1 (steering wheel) does not rotate at most 305 degrees, a neutral edge cannot be obtained.

On the other hand, in the second embodiment, the number of the reference signal notches 20 indicating the reference position is four in one rotation, so that the first rotating body 1 (steering wheel) has a maximum of 50. The neutral edge can be obtained just by rotating the angle. Therefore, an accurate absolute steering angle can be detected earlier.

In this case, as the number of the cut-out portions 20 for the reference signal increases, the neutral edge can be detected with a smaller rotation amount of the first rotating body 1. It is necessary to reduce the detection error of the absolute steering angle on the side.

The present invention is not limited to the above embodiments, but can be modified or expanded as follows. As the first detecting means, a magnetic sensor may be used instead of the optical photo-interrupter. Further, a variable resistor may be used as the second detecting means.

[0035]

As is clear from the above description, according to the present invention, the following effects can be obtained. Claim 1
According to the vehicle steering sensor, the signal indicating the rotation amount and the rotation direction of the steering wheel based on the rotation of the first rotating body that is rotated integrally with the steering wheel, and the reference position during one rotation of the steering wheel are determined. A first detecting means for outputting a signal indicative of the absolute value of the steering wheel based on a rotational position of a second rotating body provided so as to rotate the steering wheel in a range of less than one rotation via a speed reducing means. With the configuration including the second detection unit that outputs a signal indicating the steering angle, it is possible to detect an accurate absolute steering angle at an early stage.

According to the vehicle steering sensor of the second aspect, the first rotating body has a plurality of reference position signal generating means for indicating the reference position in one rotation.
An accurate absolute steering angle can be detected earlier.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a bottom view of a steering sensor portion viewed from below.

FIG. 2 is a side view of the same part viewed from the side.

FIG. 3 is a bottom view of the first rotating body.

FIG. 4 is a diagram showing a detection signal of a first detection device.

FIG. 5 is a diagram showing a relationship between a detection signal of a second detection device and a rotation angle of a worm wheel.

FIG. 6 is a block diagram showing an electrical configuration.

FIG. 7 is a flowchart of a calculation unit when detecting an absolute steering angle.

FIG. 8 is an explanatory diagram for explaining a flow when detecting an absolute steering angle.

FIG. 9 is a view corresponding to FIG. 3, showing a second embodiment of the present invention.

FIG. 10 is an explanatory diagram for explaining a flow when a conventional absolute steering angle is detected.

[Explanation of symbols]

1 is a first rotating body, 2 is a driving gear, 3 is a steering shaft, 4 is a signal slit, 5 is a reference signal notch (reference position signal generating means), and 6 is a first detecting device (first position detecting means).
, 8, 9 and 10 are first, second, and third photointerrupters, 11 is a relay gear, 12 is a worm wheel (second rotating body), 13 is a gear mechanism (reduction means),
14 is a magnet, 16 is a magnetoresistive element, 17 is a second detection device (second detection means), and 18 is a calculation unit.

Claims (2)

[Claims] A first rotating body that is integrally rotated with a steering wheel capable of rotating one or more rotations; and a rotation amount and a rotating direction of the steering wheel based on the rotation of the first rotating body. First detection means for outputting a signal indicating the reference position during one rotation of the steering wheel, and a signal indicating the reference position during one rotation of the steering wheel. A second rotating body provided to be rotated in a range of less than one rotation via a speed reducing means; and a signal indicating an absolute steering angle of the steering wheel based on a rotating position of the second rotating body. A vehicle steering sensor, comprising: a second detection unit that outputs a signal. 2. The vehicle steering sensor according to claim 1, wherein the first rotating body has a plurality of reference position signal generating means indicating a reference position in one rotation.