KR100458191B1 - detection apparatus for steering angle in vehicle - Google Patents

Abstract

The present invention relates to a steering angle detection device for a vehicle which can reduce the minimum detection angle and further accurately detect the current steering angle even if the power is cut off and returned.

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 lower gear engaged with the shaft gear at a predetermined gear ratio; An upper gear having a predetermined number of teeth; A conversion gear toothed with the upper gear while being coaxially coupled with the lower gear; A permanent magnet installed on the shaft of the lower 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; A termination piece coaxially coupled with the upper gear; The variable resistance plate which is installed in close proximity to the upper gear and is terminated by the termination contact and the resistance value is changed, and the detection signal provided from the magnetoresistive sensor and the variable resistance value are calculated and processed by a predetermined program to rotate the steering shaft. And calculation / control means for calculating the rotation 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 to solve the above problems, and provides a steering angle detection apparatus for a vehicle that can make a minimum detection angle small and further accurately detect the current steering angle even when the power is cut off and returned. There is a purpose.

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 lower gear engaged with the shaft gear at a predetermined gear ratio; An upper gear having a predetermined number of teeth; A conversion gear toothed with the upper gear while being coaxially coupled with the lower gear; A permanent magnet installed on the shaft of the lower 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; A termination piece coaxially coupled with the upper gear; The variable resistance plate which is installed in close proximity to the upper gear and is terminated by the termination contact and the resistance value is changed, and the detection signal provided from the magnetoresistive sensor and the variable resistance value are calculated and processed by a predetermined program to rotate the steering shaft. And calculation / control means for calculating the rotation 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 a plan view schematically showing the mechanical configuration of a steering angle detection apparatus of a vehicle according to another embodiment of the present invention;

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

9 is a graph showing a displacement relationship between the gears in the configuration shown in FIGS. 5 and 7.

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

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

40: steering shaft,

50: shaft gear, 52: lower digit detection gear,

54: digit conversion gear, 56: permanent magnet,

58, 58 ': upper digit detection gear,

64, 64 ': variable resistance plate, 66, 66': support member,

68, 68 ': termination contact, 70: printed circuit board,

80: housing, 90, 92: A / D converter,

92: input interface, 100: operation / control unit

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 lower digit gear (hereinafter referred to as 'lower gear') 52 which is engaged with the shaft gear 50 at a predetermined gear ratio and represents the lower digit of the steering angle, and the upper digit that represents the rotation angle of the steering shaft 40. The upper gear 58 is co-engaged with the digit gear 58 (hereinafter referred to as 'upper gear') 58 and the lower gear 52 to rotate the lower gear 52 by a predetermined angle. Seat conversion gear (hereinafter referred to as "conversion gear") 54 to be transmitted to (58), permanent magnets 56, permanent magnets 56 installed on the axis of the lower gear 52 to generate a rotating magnetic field Magnetoresistive sensor 20 installed close to the top of the terminal piece 68 is axially coupled to the upper gear 58, A support member 66 installed adjacent to the upper gear 58 and supported by the terminal piece 68 to support the variable resistance plate 68 and the variable resistance plate 68 whose resistance value changes to a predetermined height. In addition, it may include a printed circuit board 70 supporting the magnetoresistive sensor 20 and mounted with electrical circuits required for the detection device.

In the above configuration, the shift gear 50, the lower gear 52, the shift gear 54 and the upper gear 58 may all be implemented in 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 lower gear 52, so that the gear ratio between the two may be 1.5, for example. That is, when the number of teeth of the shaft gear 50 is 42, the number of teeth of the lower gear 52 may be 28. In this case, when the shaft gear 50 is rotated once, the lower gear 52 is rotated. ) Will be 1.5 revolutions, the lower gear 52 and coaxially coupled to the conversion gear 54 is also 1.5 revolutions. Of course, the number of teeth of the shaft gear 50 and the gear ratio of the shaft gear 50 and the lower gear 52 may be changed according to the required precision.

On the other hand, the gear ratio between the conversion gear 54 and the upper gear 58 may be 12, for example. In this case, the number of teeth of the conversion gear 54 is two, and the upper gear 58 You can have 24 teeth. However, in the present embodiment, the upper gear 58 is constituted with 12 teeth, which is 1/2 of the teeth, in the state of maintaining the above gear ratio 12. That is, in the state which implemented the upper gear 58 in semicircle shape so that only 12 teeth remain, the variable resistance plate 64 is provided in the remaining semicircle part. Of course, the number of teeth of the conversion gear 54 and the gear ratio between the upper gear 58 and the conversion gear 54 may be appropriately changed.

Assuming that the steering shaft 40, ie the shaft gear 50, rotates two in the left and right directions from the neutral point, respectively, by this gear structure, the lower gear 52 and the shift gear 54 at the neutral point. 3 turns each in the left and right directions, and the upper gear 58 rotates each 1/4 turn in the left and right directions at its neutral point, that is, in the range of 1/2 turn (180 °) as a whole. Accordingly, the terminal contact piece 68 is moved between its minimum and maximum positions while being mounted on the variable resistance plate 64.

FIG. 7 is a plan view schematically illustrating a mechanical configuration of a steering angle detecting apparatus for a vehicle according to another exemplary embodiment. The same reference numerals are given to the same parts as those illustrated in FIG. 5, and detailed descriptions thereof are omitted. In the embodiment of Fig. 7, a semicircular concentric hole 58a is formed inside the upper gear 58 'in a state where the upper gear 58' is formed in a disc shape, and the lower part of the concentric hole 58a is variable. The resistor plate 64 'is provided so that the terminal contact piece 68' moves on the variable resistor plate 64 '.

8 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. 8, 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 in analog form from the magnetoresistive sensor 20 and the magnetoresistive sensor 20, respectively. Analog-to-Digital (A / D) converter 90 for converting to V, terminating contact 68, 68 'moving from variable resistor plate 64, 64' connected between power supply voltage Vcc and ground The digital detection signal output from the A / D converter 92 and the A / D converter 90 and 92 for converting the analog detection voltage value of the digital value into It may be made to include a calculation / control unit 100 to substitute the conversion formula or table to finally calculate the rotation direction and the rotation angle of the steering shaft (40).

In the above-described configuration, the operation / control unit 100 may be implemented as a microprocessor unit or dedicated control logic. The A / D converters 90 and 92 may be integrally provided in the microprocessor unit or implemented as separate elements.

9 is a graph showing a displacement relationship between the gears in the configuration shown in FIGS. 5 and 7. As shown in FIG. 9, the lower gear 52 and the shift gear 54 rotate by 540 ° while the shaft gear 50 rotates by 360 °, and the magnetoresistive sensor 20 lower gear 52. Whenever rotates by 180 °, the angle shift value within the range of 0-180 ° is repeatedly outputted in proportion to it.

On the other hand, the upper gears 58, 58 'are rotated by an angle corresponding to one tooth (15 ° in this embodiment) whenever the lower gear 52 rotates by 180 °, and consequently the termination piece 68 , 68 'is rotated by 15 ° on the variable resistance plate 64, 64', and thus, knowing the current resistance value, the number of revolutions of the steering shaft 40 can be known.

Then, in accordance with such a relationship, the calculation / control unit 100 current resistance value information terminated by the termination pieces 68 and 68 'in the conversion table based on Equation 2 or Equation 2 below. And the rotation angle of the lower gear 52 and the gear ratio between the gears, the unknown rotation direction and the rotation angle of the steering shaft 40 can be known.

In Equation 2 above, Denotes the rotation angle of the shaft gear 50, that is, the steering wheel, Denotes the rotation angle of the upper gears 58, 58 ', that is, the angle represented by the resistance value terminated by the termination pieces 68, 68', Represents the rotation angle of the lower gear 52, Denotes the gear ratio between the shaft gear 50 and the lower gear 52, Denotes the gear ratio between the upper gear 58, 58 'and the conversion gear 54.

The displacement of the unknown shaft gear in FIG. In this case, by substituting the angle represented by the gear ratio and the value detected by the magnetoresistive sensor 20 and the resistance value terminated by the termination pieces 68 and 68 ', which are 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 magnetoresistive sensor, the phase between the variable resistance plate and the terminal contact of the upper gear, etc. are properly neutralized when manufacturing the vehicle. Although the point detecting means is not necessary, the neutral point detecting means as shown in FIG. 1 may be further provided in consideration of a detection error according to the secular variation of the vehicle.

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 detection device of the vehicle of the present invention as described above, since the device is implemented using a magnetoresistive sensor having a higher resolution than the photo interrupt, the steering angle can be detected more precisely. Even if it is removed and returned, there is an effect that it is possible to accurately detect the current rotation angle of the steering shaft.

Claims (4)

A shaft gear axially coupled to a steering shaft of the vehicle and having a predetermined number of teeth; A lower gear engaged with the shaft gear at a predetermined gear ratio; An upper gear having a predetermined number of teeth; A conversion gear toothed with the upper gear while being coaxially coupled with the lower gear; A permanent magnet installed on the shaft of the lower 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; A termination piece coaxially coupled with the upper gear; A variable resistor plate installed close to the upper gear and terminated by the terminal contact piece to change a resistance value; And a calculation / control means for calculating the rotation direction and the rotation angle of the steering shaft by calculating and processing the detection signal provided from the magnetoresistive sensor and the variable resistance value by a predetermined program. 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; The shaft gear, the lower gear, the shift gear and the upper gear are spur gears of a disc with 42, 28, 2 and 24 teeth, respectively; A semicircular band-shaped concentric hole is formed on the upper gear; The variable resistance plate is fixed to a lower portion of the concentric hole; And the terminal contact piece moves the variable contact plate through the concentric hole. 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; The shaft gear, the lower gear and the shift gear are spur gears of a disc having 42, 28 and 2 teeth, respectively, and the upper gear is a spur gear of a semicircle having 12 teeth; A variable resistance plate having a circular shape when fixed with the upper gear is fixed to an outer lower portion of the upper gear; The terminal contact piece is a steering angle detection device for a vehicle, characterized in that for moving the variable contact plate.