KR20190020859A - Non-contact type rack stroke sensor - Google Patents

Abstract

According to the present invention, a non-contact type rack stroke sensor detects the position of a rack for rear wheel steering, and comprises: a sensor unit provided with a transmitter and a receiver, and installed to be adjacent to the rack; and a reflective unit installed in the rack in a position opposite to the sensor unit to integrally reciprocate along with the rack, and having an external diameter that is formed to be gradually larger from one end to the other end in the longitudinal direction of the rack.

Description

[0001] NON-CONTACT TYPE RACK STROKE SENSOR [0002]

The present invention relates to a non-contact type rack-stroke sensor, and more particularly, to a non-contact type rack-stroke sensor that senses the position of a rack for rear-wheel steering.

BACKGROUND ART Recently, application of rear wheel steering (RWS) to rotate a rear wheel to reduce a turning radius of a vehicle or to improve operability in a curve has been expanded.

The rear wheel steering is realized by moving the rack connecting between the left wheel and the right wheel of the rear wheel in the left and right directions and rotating the rear wheel left and right wheels at a predetermined angle.

At this time, it is necessary to locate the rack and rotate the rear wheel at an accurate angle to maximize the operability of the automobile. Therefore, a sensor for detecting the position of the rack should be installed.

Conventionally, as shown in FIGS. 1 and 2, the position of the rack, that is, the rack stroke, was measured using a linear variable differential transformer (LVDT) sensor.

The sensor 40 is moved in the left and right direction together with the rack 10 and the movement of the sensor 40 is detected by the sensor 30 It is a way to detect.

The fixed sensor 40 is constituted by a base 41, an iron core 42 provided on the base 41, and a bolt 43 connecting the base 41 and the rack 10, Is composed of an LVDT sensor including a first coil (31), a second coil (32) and a third coil (33).

When the iron core 42 provided at the upper end of the fixed sensor 40 is inserted into the measurement sensor 30, the distance between the first coil 31 and the second coil 32 and / The position of the iron core 42 can be specified by measuring the changing voltage through the change of the magnetic field as the iron core 42 is positioned between the three coils 33. [

That is, the amount of magnetic flux near the iron core 42 increases and the induced voltage amount increases, and the position of the iron core is measured by using the difference.

However, when using such an LVDT sensor, part of the fixed sensor and the measuring sensor are partially abutted, which causes the vibration to be transmitted directly from the wheel to the measuring sensor. As a result, not only sensing noise but also durability and corrosion resistance of the sensor may be deteriorated.

Therefore, there is a demand for a completely non-contact type rack stroke sensor in order to minimize sensing noise due to vibration and the like.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

KR 10-2012-0063190 (June 15, 2012)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-contact type rack-stroke sensor capable of minimizing sensing noise and accurately measuring the position of a rack.

In order to accomplish the above object, a non-contact type rack stroke sensor according to an embodiment of the present invention is a non-contact type sensor for sensing the position of a rear wheel steering rack, and includes a sensor unit provided adjacent to the rack, And a reflector formed in the rack at a position opposite to the sensor unit so as to be able to reciprocate integrally with the sensor unit and having an outer diameter gradually increasing from one end toward the other end along the longitudinal direction of the rack.

The reflector may include a body formed in a conical column shape having a radius of an outer circumferential surface that varies along a longitudinal direction of the rack and installed on an outer circumferential surface of the rack, And a pair of stoppers formed in a ring shape.

And a stopper formed to surround the rack and open at a position corresponding to the sensor unit. The stopper contacts the inner surface of the opening formed in the housing, and restricts the movement distance of the rack. do.

The sensor unit emits light or ultrasonic waves from the transmitter, and the receiver or the receiver senses light or ultrasonic waves reflected from the reflection unit.

The sensor unit may determine the position of the rack using a time difference (t) between a time point at which light or ultrasonic waves are emitted from the transmitter and a time at which light or ultrasonic waves are detected at the receiver.

The sensor unit calculates the current position (x) of the rack calculated by the following formula (2) using the distance (h) between the rack and the sensor calculated by the following formula (1).

Equation 1: h = 0.5 x t x v

Equation 2: x = (H-h) x tan (90-a)

(Where v is the speed of light or ultrasonic waves, H is the distance between the outer surface of the rack and the transmitter or receiver, and a is the angle between the outer surface of the rack and the outer surface of the reflective portion).

The non-contact type rack stroke sensor according to the present invention has the following effects.

First, since the sensor and the rack are physically separated completely, sensing noise due to vibration and the like can be originally prevented.

Second, the position of the rack can be grasped precisely by changing the distance between the sensor part and the reflecting part.

Third, it is possible to precisely control the position of the rack to improve the operability at the time of traveling the curve.

1 is a side view showing a state of a conventional rack stroke sensor,
FIG. 2 is a block diagram showing the operation of a conventional rack-stroke sensor,
3 (a) is a perspective view of a reflection part according to an embodiment of the present invention,
Fig. 3 (b) is a perspective view showing a state in which the reflection portion is provided in the rack,
4 is a side view showing one embodiment of a non-contact type rack-stroke sensor according to the present invention,
Fig. 5 is a diagram showing variables of a calculation formula for measuring the position of a rack.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, a non-contact type rack stroke sensor according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention relates to a sensor for locating a rack in an RWS (Rear Wheel Steering) system in which rear wheels can be steered by moving a rack connecting rear left and right wheels to the left and right. Here, the detailed configuration of the RWS system, i.e., the driving unit for driving the rack or the rack, is outside the scope of the present invention, and thus a detailed description thereof will be omitted.

3 (a) is a perspective view of a reflector according to an embodiment of the present invention, Fig. 3 (b) is a view showing a state where the reflector is installed in a rack, Fig. 4 is a perspective view of a non-contact type rack stroke sensor And FIG. 5 is a diagram showing variables of a calculation formula for measuring the position of a rack.

3 and 4, the non-contact type rack-stroke sensor according to the present invention includes a sensor unit 200 and a reflection unit 100. As shown in FIG.

At this time, the rack 10 is installed by being enclosed in a housing 20 fixed to the vehicle body, and is installed so as to reciprocate in the left and right direction within the housing 20. An opening portion through which the rack 10 is exposed to the outside is formed in a predetermined region of the housing 20, and the sensor portion 200 and the reflection portion 100 are provided in the opening portion.

The sensor unit 200 includes a transmitter 210 that emits light or ultrasound waves and a receiver 220 that emits light from the transmitter 210 and detects light or ultrasound reflected from the reflector 100 The transmitter 210, and the receiver 220 may be installed in the sensor body 110.

The transmitter 210 may be a laser oscillator for emitting light or a speaker for emitting ultrasonic waves, and the receiver 220 may be a photon sensor for sensing light or a microphone for sensing ultrasonic waves.

However, the transmitter 210 and the receiver 220 are not limited to these, and any method may be employed as long as it is possible to measure the interval between the two configurations using the time difference between the emission-reflection-reception.

The reflector 100 is divided into a main body 110 and a stopper 120 so as to be inserted into the rack 10 and reflects light or ultrasonic waves emitted from the transmitter 210 to the receiver 220. At this time, the gap between the reflection unit 100 and the sensor unit 200 changes according to the position of the rack 10, and the time for the light or ultrasonic wave emitted from the transmitter 210 to reach the receiver 220 is changed So that the current position of the rack 10 can be precisely grasped.

The main body 110 is formed in a pipe shape whose outer circumferential surface is a conical columnar shape and has a shape in which the radius increases from one end toward the other end. At this time, the inner circumferential surface of the main body 110 is formed in a shape corresponding to the outer circumferential surface of the rack 10, so that the main body 110 is engaged with the outer circumferential surface of the rack 10 to reciprocate integrally with the rack 10 Respectively.

The main body 110 is preferably made of a material having a high reflectance for light or ultrasound and a low transmittance and a low absorption rate or coated with such a material. Accordingly, the amount of light or ultrasound reflected from the main body 110 reaches the receiver 220, thereby increasing the sensitivity of the sensor.

The stopper 120 is formed in an annular shape extending from both ends of the main body 110, that is, an upper surface and a lower surface of a conical column, respectively. It is preferable that the inner circumferential surface of the stopper 120 is formed in a shape corresponding to the outer circumferential surface of the rack 10 and the outer diameter of the stopper 120 is larger than the largest outer diameter of the body 110. [

The stopper 120 is configured to limit the degree of movement of the reflector 100 and the rack 10 coupled thereto. The outer surface of the stopper 120, that is, the surface of the stopper 120 opposite to the surface of the main body 110, is in contact with the inner surface of the housing 20. In other words, as the rack 10 moves, So that the reflection portion 100 is prevented from moving beyond a predetermined region.

In addition, the stopper 120 is preferably made of an elastic material so as to absorb shock. The stopper 120 is formed of an elastic material and the outer diameter of the stopper 120 is formed to be larger than the outer diameter of the main body 110 so that the reflective portion 100 is caused to collide with the inner surface of the housing 20 due to excessive movement of the rack 10. [ The amount of impact applied to the main body 110 can be reduced.

Hereinafter, the operation of the non-contact type rack-stroke sensor according to the present invention and a method of specifying the position of the rack using the non-contact type rack-stroke sensor will be described.

As shown in FIG. 5, the time difference (t) from when the light or the ultrasonic wave is emitted from the transmitter 210 to the time when the receiver 220 detects the echo reflected from the main body 110 is measured .

Since the speed v of the light emitted from the transmitter 210 or the velocity v of the ultrasonic wave is constant, the interval h between the transmitter 210 and the main body 110 is calculated using Equation 1 based on the time difference t .

Equation 1: h = 0.5 x t x v

The lateral position of the main body 110 can be specified using the following Equation 2 because the angle formed by the outer peripheral surface of the main body 110 and the outer peripheral surface of the rack 10 is constant.

Equation 2: x = (H-h) x tan (90-a)

Here, x is a distance from one end of the body 110 having the smallest outer diameter, H is a distance from the transmitter 210 or the receiver 220 to one end of the body 110, 110 is an angle formed by the outer peripheral surface of the rack 10 and the outer peripheral surface of the rack 10.

That is, only by measuring the time difference (t) between the launching time of the transmitter 210 and the detection time of the receiver 220, the position of the rack 10 in which the main body 110 and the main body 110 are installed can be precisely detected It will be possible to do.

By adjusting the position of the rack in the RWS system based on the detected position of the rack 10, the rotation angle of the rear wheel can be controlled more precisely, thereby reducing the turning radius in the curve or improving the operability .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

10: rack 20: housing
30: measuring sensor 31: first coil
32: second coil 33: third coil
40: Fixed sensor 41: Base
42: iron core 43: bolt
100: reflector 110:
120: stopper 200: sensor unit
210: Emitter 211: Light or ultrasonic (firing)
220: receiver 221: light or ultrasonic (detection)
230:

Claims (6)

A non-contact sensor for sensing the position of a rear wheel steering rack,
A sensor unit having a transmitter and a receiver installed adjacent to the rack;
And a reflector installed in the rack at a position opposite to the sensor unit so as to reciprocate integrally with the rack and having an outer diameter gradually increasing from one end toward the other end along the longitudinal direction of the rack , Non-contact rack-stroke sensor.
The method according to claim 1,
The reflector may include a body formed in a conical column shape having a radius of an outer circumferential surface that varies along a longitudinal direction of the rack and installed on an outer circumferential surface of the rack, And a pair of stoppers formed in an annular shape.
The method of claim 2,
Further comprising a housing formed to surround the rack, the housing corresponding to the sensor unit being opened,
Wherein the stopper contacts the inner surface of the opening formed in the housing to limit the moving distance of the rack.
The method according to claim 1,
Wherein the sensor unit emits light or ultrasonic waves from the transmitter and detects light or ultrasonic waves reflected from the reflection unit by the receiver.
The method of claim 4,
Wherein the sensor unit determines the position of the rack using a time difference (t) between a time point at which light or ultrasonic waves are emitted from the transmitter and a time point at which light or ultrasonic waves are detected at the receiver, .
The method of claim 5,
Wherein the sensor unit calculates the current position (x) of the rack calculated by the following equation (2) by using the distance (h) between the rack and the sensor calculated by the following formula (1) .
Equation 1: h = 0.5 x t x v
Equation 2: x = (Hh) x tan (90-a)
(Where v is the speed of light or ultrasonic waves, H is the distance between the outer surface of the rack and the transmitter or receiver, and a is the angle between the outer surface of the rack and the outer surface of the reflective portion).

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