KR100460421B1 - detection apparatus for steering angle in vehicle - Google Patents

Abstract

The present invention relates to a steering angle detection apparatus for a vehicle that adopts a magnetoresistive sensor to reduce the minimum detection angle.

An apparatus for detecting a steering angle of a vehicle according to the present invention includes a shaft gear axially coupled to a steering shaft of a vehicle and having a predetermined number of teeth; A detection gear meshed with the shaft gear at a predetermined gear ratio; A permanent magnet installed on the shaft of the detection gear to generate a rotating magnetic field; A magnetoresistive sensor installed close to the upper portion of the permanent magnet to detect a rotation angle of the rotating magnetic field within a predetermined angle range; Counting means for counting the number of times the detection value of the magnetoresistive sensor exceeds the angular range and the counting count of the magnetoresistive sensor detection value and the counting means by arithmetic processing by a predetermined program to rotate and rotate the steering shaft. Calculation / control means for calculating the angle.

Description

Detection apparatus for steering angle in vehicle

The present invention relates to an apparatus for detecting a steering angle of a vehicle, and more particularly, to an apparatus for detecting a steering angle of a vehicle implemented using a magnetoresistive sensor.

Various devices capable of detecting the rotation angle of the rotating body have been proposed. Such a rotation angle detection device can be used, for example, in a steering angle detection device of a vehicle. In more detail, in the vehicle, a steering angle detection device is adopted to perform roll suppression during steering in performing damping force control of the shock absorber, and so on. FIG. 1 illustrates a structure of a conventional steering angle detection device of a vehicle. 2A and 2B are diagrams showing detection waveforms at the time of turning right and left at the apparatus of FIG. 1, respectively. As shown in FIG. 1, in a conventional steering angle detection apparatus of a vehicle, a slit disc 14 is inserted outside the steering shaft 11, and a plurality of slits 12 are formed on concentric circles of the edge of the slit disc 14. It is drilled at equal intervals. On the other hand, two pairs of photo interrupts 16 and 17 made up of light receiving elements and light emitting elements respectively disposed on both sides with the slit disc 14 interposed therebetween are fixed to a steering column tube (not shown).

In the above-described configuration, when the slit 12 is positioned between the light emitting element and the light receiving element of the photo interrupts 16 and 17 as the steering shaft 11 rotates, the light generated by the light emitting element is transmitted to the light receiving element. On the contrary, when the slit periphery is positioned, on / off pulses are generated in the light receiving element whenever the steering angle is 9 ° due to the principle that light generated in the light emitting element is not transmitted to the light receiving element. Furthermore, a phase difference of 4.5 ° is made between the two pairs of photo interrupts 16 and 17 to determine the rotational direction of the steering shaft 11. That is, as shown in FIG. 2A, when the signal state of one photo interrupt 16 rises, if the signal state of the other photo interrupt 17 is high (H) level, it is determined to turn right. On the contrary, as shown in FIG. 2B. If it is the low level L, it is discriminated as turning left.

In FIG. 1, reference numeral 13 denotes a neutral point detecting slit of the steering shaft 11, and 15 denotes a photo interrupt for detecting whether the neutral point detecting slit 11 passes.

However, according to the conventional steering angle detection apparatus of the vehicle as described above, the minimum detection angle is determined because the interval of each slit is determined in consideration of the detection resolution of the photo interrupt in a state in which the slit disc cannot be enlarged indefinitely due to the limitation of the installation space. There is a problem that can not be made small.

In particular, in the conventional apparatus, since the steering angle is calculated in a relative manner based on the number of pull signals counted from the point of time when the neutral point signal is input, when the power is cut off for some reason, the power is turned on again within a short time. Since the count values are all erased, there is a problem in that the steering angle state of the current vehicle cannot be determined at all.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and an object thereof is to provide a steering angle detecting apparatus for a vehicle in which a minimum detection angle can be reduced by adopting a magnetoresistive sensor.

Steering angle detection apparatus for a vehicle of the present invention for achieving the above object is a shaft gear coupled to the steering shaft of the vehicle and having a predetermined number of teeth; A detection gear meshed with the shaft gear at a predetermined gear ratio; A permanent magnet installed on the shaft of the detection gear to generate a rotating magnetic field; A magnetoresistive sensor installed close to the upper portion of the permanent magnet to detect a rotation angle of the rotating magnetic field within a predetermined angle range; Counting means for counting the number of times the detection value of the magnetoresistive sensor exceeds the angular range and the counting count of the magnetoresistive sensor detection value and the counting means by arithmetic processing by a predetermined program to rotate and rotate the steering shaft. Calculation / control means for calculating the angle.

1 is a perspective view for explaining the structure of a conventional steering angle detection apparatus of a vehicle,

2A and 2B show detection waveforms at the right turn and the left turn, respectively, in the apparatus of FIG. 1;

3 is a view for explaining the detection principle of the magnetoresistive sensor used in the steering angle detection device of a vehicle according to an embodiment of the present invention;

4 is a detection output waveform diagram of a magnetoresistive sensor;

5 is a plan view schematically showing the mechanical configuration of a steering angle detection device of a vehicle of the present invention;

6 is a schematic cross-sectional view taken along line A-A of FIG. 5;

7 is an electrical block diagram of an apparatus for detecting a steering angle of a vehicle according to the present invention;

8 is a graph showing a displacement relationship between the gears in the configuration shown in FIG.

*** Explanation of symbols for the main parts of the drawing ***

20: magnetoresistive sensor, 22, 24: bridge element,

40: steering shaft, 50: shaft gear,

52: detection gear, 56: permanent magnet,

70: printed circuit board, 80: housing,

90: A / D converter, 100: operation / control unit,

102: counter

Hereinafter, a steering angle detecting apparatus for a vehicle according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view illustrating a detection principle of a magnetoresistive sensor used in a steering angle detection apparatus of a vehicle according to a preferred embodiment of the present invention, and FIG. 4 is a detection output waveform diagram of the magnetoresistive sensor. As shown in FIG. 3, when an external rotating magnetic field B is applied to the magnetoresistive sensor 20 having two magnetoresistive bridge elements 22 and 24 arranged to be turned by 45 ° from each other, as shown in FIG. In the output terminals U1 and U2 of the bridge elements 22 and 24, as shown in FIG. 4, two sinusoidal signals VU1 and VU2 having a period of 180 degrees and a phase difference of 45 degrees are generated. Will be obtained. At this time, if the amplitudes of the sinusoidal signals VU1 and VU2 are the same, the current angle θ of the external rotating magnetic field B can be calculated by the following equation (1).

As the magnetoresistive sensor described above, an anisotropic magneto resistive sensor made of a permalloy (registered trademark) thin film, which is a kind of iron and nickel alloys, may be preferably used. In Fig. 3, reference signs Vcc1 and Vcc2 denote power supply voltages applied to the bridge elements 22 and 24, respectively, and + Vo1 and -Vo1 denote the positive output voltage and the negative output voltage of the bridge element 22, respectively. + Vo2 and -Vo1 represent the positive output voltage and the negative output voltage of the bridge element 24, respectively.

FIG. 5 is a plan view schematically illustrating a mechanical configuration of a steering angle detection device of a vehicle of the present invention, and FIG. 6 is a schematic cross-sectional view taken along line A-A of FIG. 5.

As shown in Figs. 5 and 6, the mechanical configuration of the steering angle detection device of the vehicle of the present invention is a housing 80 in which the device is housed, a shaft gear 50 inserted outside the steering shaft 40 of the vehicle. , The detection gear 52 which is coupled to the shaft gear 50 at a predetermined gear ratio to indicate the steering angle, and the permanent magnet 56 and the permanent magnet 56 installed on the axis of the detection gear 52 to generate a rotating magnetic field. The magnetoresistive sensor 20 and the magnetoresistive sensor 20 are installed close to each other, and the printed circuit board 70 mounted with the electric circuits necessary for the detection device may be included.

In the above-described configuration, both the shift gear 50 and the detection gear 52 can be implemented as spur gears. In addition, it is preferable that the number of teeth of the shaft gear 50 is larger than the number of teeth of the detection gear 52, so that the gear ratio between the two may be, for example, 1.5. In other words, when the number of teeth of the shaft gear 50 is 42, the number of teeth of the detection gear 52 may be 28, in which case the detection gear 52 is rotated when the shaft gear 50 is rotated once. ) Will make 1.5 turns. Of course, the number of teeth of the shaft gear 50 and the gear ratio of the shaft gear 50 and the detection gear 52 may be changed according to the required precision.

Assuming that the steering shaft 40, ie the shaft gear 50, rotates two in the left and right directions at the neutral point, respectively, by the gear structure, the detection gear 52 is respectively in the left and right directions at the neutral point. You make three turns.

7 is an electrical block diagram of an apparatus for detecting a steering angle of a vehicle according to the present invention. As shown in FIG. 7, the electrical configuration of the steering angle detection apparatus of the vehicle according to the present invention is a digital signal having a magnitude corresponding to the detection signal output from the magnetoresistive sensor 20 and the magnetoresistive sensor 20 in analog form, respectively. The analog-to-digital (A / D) converter 90 and the digital detection signal output from the A / D converter 90 are processed by Equation 1, and then substituted into a predetermined conversion formula or table. Finally, the counter 102 stores the rotation speed and direction of the detection gear 52 according to the instructions of the calculation / control unit 100 and the calculation / control unit 100 for calculating the rotation direction and the rotation angle of the steering shaft 40. It can be made, including).

In the above-described configuration, the operation / control unit 100 may be implemented as a microprocessor unit or dedicated control logic. The A / D converter 90 may be integrally provided in the microprocessor unit or implemented as a separate element, and the counter 102 may also be implemented as a hardware element separate from the microprocessor unit or by software means within the microprocessor unit. Could be implemented.

8 is a graph showing a displacement relationship between the gears in the configuration shown in FIG. As shown in FIG. 8, the detection gear 52 is rotated by 540 ° while the shaft gear 50 is rotated by 360 °, and the magnetoresistive sensor 20 is rotated by the detection gear 52 by 180 °. Each time, the angular shift value within the range of 0-180 ° is repeatedly output in proportion to this. In addition, whenever the angular shift value of the magnetoresistive sensor 20 suddenly changes from 180 ° to 0 °, the operation / control unit 100 instructs the counter 102 to count the number of sudden changes.

In accordance with such a relationship, the calculation / control unit 100 determines the gear ratio between the shaft gear 50 and the detection gear 52 and the counter 102 in the conversion table based on Equation 2 or Equation 2 below. The unknown rotation direction and the rotation angle of the steering shaft 40 can be known by substituting the number of times counted by (refer to 1/2 rotation as one in this embodiment) and the detection value of the magnetoresistive sensor 20. .

In Equation 2 above, Denotes the rotation angle of the shaft gear 50, that is, the steering wheel, Represents the number of revolutions counted at counter 102, Represents the rotation angle of the detection gear 52, Denotes a gear ratio between the shaft gear 50 and the detection gear 52.

8 the displacement of the unknown shaft gear 50 Suppose that is, by substituting the gear ratio and the value detected in the magnetoresistive sensor 20 already known in Equation 2 above It can be seen that this is 450 degrees.

On the other hand, in the present invention, if the steering shaft, the phase between each gear, the phase of the permanent magnet and the magnetoresistance sensor is properly fixed during the manufacture of the vehicle, a separate neutral point detection means is not required, In consideration of the detection error may be further provided with a neutral point detection means as shown in Figure 1 may be to detect the neutral point.

The steering angle detection apparatus for a vehicle of the present invention is not limited to the above-described embodiments, and can be variously converted and implemented within the range allowed by the technical idea of the present invention. For example, in the above-described embodiment, it has been described that two bridge elements are included in the magnetoresistive sensor. However, the present invention is not limited thereto, and a known single bridge element or a resistor split type may be used.

According to the steering angle detecting apparatus for a vehicle of the present invention as described above, since the apparatus is implemented using a magnetoresistive sensor having a higher resolution than the photo interrupt, the steering angle can be detected more precisely.

Claims (3)

A shaft gear axially coupled to a steering shaft of the vehicle and having a predetermined number of teeth; A detection gear meshed with the shaft gear at a predetermined gear ratio; A permanent magnet installed on the shaft of the detection gear to generate a rotating magnetic field; A magnetoresistive sensor installed close to the upper portion of the permanent magnet to detect a rotation angle of the rotating magnetic field within a predetermined angle range; Counting means for counting the number of times the detected value of the magnetoresistive sensor exceeds the angle range; And a calculation / control means for calculating the magnetoresistive sensor detected value and the count number of the counting means by a predetermined program to calculate the rotational direction and the rotational angle of the steering shaft. 2. The steering angle detection apparatus of a vehicle according to claim 1, wherein the magnetoresistive sensor is made of an anisotropic magnetoresistive sensor. 3. The magnetoresistance sensor according to claim 1 or 2, wherein the magnetoresistive sensor comprises two bridge elements having a phase difference of 45 DEG from each other; And the shaft gear and the detection gear are spur gears having 42 teeth and 28 teeth, respectively.