Pretreatment apparatus and method of wheel speed

Abstract

An apparatus for pretreating a wheel speed includes a tone wheel having a plurality of teeth, a hall sensor configured to detect a measurement angle including an offset of each of the teeth, an offset correcting unit configured to correct the measurement angle with a corrective offset when disturbance is generated and a frequency estimating unit configured to estimate a frequency based on a result value calculated from the offset correcting unit.

Claims

1. An apparatus for pretreating a wheel speed for improving an accuracy in estimating a frequency of the wheel speed in disturbance, comprising: a disk coupled to a wheel of a vehicle; a tone wheel including a plurality of teeth, wherein the tone wheel is coupled to the disk; a hall sensor, wherein the hall sensor is installed in the vehicle such that the hall sensor detects each of the plurality of teeth of the tone wheel, and a measurement angle and an offset of each of the plurality of teeth of the tone wheel, wherein the hall sensor generates a speed signal using a frequency of rotation of the tone wheel based on the angle and the offset of each of the plurality of teeth of the tone wheel, and wherein the hall sensor determines a disturbance based on the angle and the offset of each of the plurality of teeth of the tone wheel; a wheel sensor, the wheel sensor detecting the speed signal and the disturbance; and a Tire Pressure Monitoring System (TPMS), the TPMS indicting an air pressure of a tire with an improved accuracy in the estimated frequency of the speed signal by correcting a detection error of the wheel sensor caused by the disturbance at the time air pressure of a tire is estimated from the speed signal, wherein the TPMS includes; an offset correcting unit, the offset correcting unit calculating a corrective offset and correcting the measurement angle with the calculated corrective offset when a disturbance is detected, the offset correcting unit further adding the calculated corrective offset to the measurement angle; and a frequency estimating unit, the frequency estimating unit estimating a frequency of the speed signal generated by the hall sensor based on a result value calculated from the offset correcting unit, wherein the offset correcting unit applies the corrective offset to or from the measurement angle of each of the plurality of teeth.

2. The apparatus of claim 1, wherein the corrective offset is calculated by dividing a sum of the offset by the number of the plurality of teeth.

3. A method of pretreating a wheel speed for improving an accuracy in estimating a frequency of the wheel speed in disturbance, comprising the steps of: (a) detecting a plurality of teeth of a tone wheel, at a hall sensor, and obtaining a measurement angle including an offset of each of the plurality of teeth, wherein the hall sensor is installed in the vehicle such that the hall sensor detects each of the plurality of teeth of the tone wheel, and a measurement angle and an offset of each of the plurality of teeth of the tone wheel, wherein the hall sensor generates a speed signal using a frequency of rotation of the tone wheel based on the angle and the offset of each of the plurality of teeth of the tone wheel, and wherein the hall sensor determines a disturbance based on the angle and the offset of each of the plurality of teeth of the tone wheel; (b) detecting a speed signal at a wheel sensor; (c) calculating a corrective offset at a Tire Pressure Monitoring System (TPMS) when a disturbance is generated; (d) correcting the measurement angle at the TPMS by using the calculated corrective offset; (e) estimating a frequency of the speed signal generated by the hall sensor based on a result value calculated in step (c) and (d) at the TPMS; (f) applying the corrective offset to or from the measurement angle of each of the plurality of teeth at the TPMS, and (g) notifying, at the TPMS, a driver of an air pressure of a tire with an improved accuracy in the estimated frequency of the speed signal by correcting a detection error of the wheel sensor caused by the disturbance at the time air pressure of a tire is estimated from the speed signal.

4. The method of claim 3, wherein the corrective offset is calculated by dividing a sum of the offset by the number of the plurality of teeth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram illustrating an ideal angle of each tooth of a tone wheel.

(2) FIGS. 2A and 2B are diagrams illustrating frequency estimation results at the same angular speed of a wheel according to existence/non-existence of an angle error.

(3) FIGS. 3 and 4 are diagrams illustrating a wheel speed pretreatment apparatus according to an exemplary embodiment of the present invention.

(4) FIG. 5 is a diagram illustrating an ideal case of a tone wheel of the wheel speed pretreatment apparatus according to the exemplary embodiment of the present invention.

(5) FIG. 6 is a diagram illustrating a real case of a tone wheel of the wheel speed pretreatment apparatus according to the exemplary embodiment of the present invention.

(6) FIGS. 7A and 7B are diagrams illustrating a state before and after a correction by a corrective offset of the wheel speed pretreatment apparatus according to the exemplary embodiment of the present invention.

(7) FIG. 8 is a diagram illustrating a wheel speed pretreatment method according to an exemplary embodiment of the present invention.

(8) It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

(9) In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

(10) Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to clarify a method of solving the technical problems of the present invention. However, in the description of the present invention, descriptions of publicly-known related technologies incorporated herein will be omitted when it is determined that the descriptions of the publicly-known related technologies may obscure the subject matter of the present invention. The terms used in the following description are defined considering the functions of the present invention and may vary depending on the intention or usual practice of a designer or manufacturer. Therefore, the definitions should be made based on the entire contents of the present specification. Parts indicated by like reference numerals (reference numbers) refer to like elements throughout the specification.

(11) Hereinafter, a wheel speed pretreatment apparatus and method according to an exemplary embodiment of the present invention will be described.

(12) As illustrated in FIG. 3, a vehicle may include a disk 20 which is mounted in a hub 10 coupled to a wheel (not illustrated) and is rotated together with the hub 10. Here, in the disk 20, an internal plate 21 and an external plate 22 may be integrally formed by a rib 23 which is radially formed therebetween.

(13) The vehicle may include a tone wheel 30 which is coupled to a wheel shaft 11, which penetrates the disk 20, and is rotated together when the disk 20 is rotated, and a hall sensor 40, which is proximately installed to the tone wheel 30, and detects the tone wheel 30 and generates a speed signal.

(14) Here, the tone wheel 30 is formed to have an appearance in which a sawtooth shape including a plurality of teeth 31 and a plurality of valleys 32 is repeatedly formed on an outer peripheral surface shaped like a disk.

(15) The hall sensor 40 generates a speed signal by using a frequency generated according to a rotation of the tone wheel 30.

(16) As illustrated in FIGS. 3 and 4, the wheel speed pretreatment apparatus according to the exemplary embodiment of the present invention may include the tone wheel 30, the hall sensor 40, an offset correcting unit 50, and a frequency estimating unit 60.

(17) Referring to FIG. 5, for the tone wheel 30 provided with four teeth 31, an entire angle is 4X during one rotation. Here, X indicates an ideal angle between the teeth 31. In FIG. 5, X is illustrated based on a virtual line L.

(18) However, referring to FIG. 6, in actual, for each tone wheel 31, X.sub.1=X+offset.sub.1+offset.sub.2, X.sub.2=Xoffset.sub.2, X.sub.3=Xoffset.sub.3, and X.sub.4=X+offset.sub.3offset.sub.1, which are measurement angles, are detected. That is, an offset may exist between the teeth 31.

(19) However, since X.sub.1+X.sub.2+X.sub.3+X.sub.4=4X, the measurement angles have the same entire angle during one rotation.

(20) Accordingly, as expressed by Equation 1 below, it is possible to calculate a corrective offset by dividing the sum of offsets by the number N of teeth 31.

(21) $\begin{array}{cc}\mathrm{correctiveOffset}=\frac{.Math.\mathrm{offset}}{\mathrm{number}\mathrm{of}\mathrm{teeth}}& \left[\mathrm{Equation}1\right]\end{array}$

(22) Accordingly, when there is no distortion caused by disturbance, a value of the corrective offset may be 0.

(23) However, when there is a value of the corrective offset, this is determined as an influence caused by disturbance, and an angle error is corrected with the corrective offset.

(24) That is, when it is impossible to accurately estimate a frequency by disturbance, the offset correcting unit 50 of the wheel speed pretreatment apparatus 1 estimates a frequency by correcting the angle error with the correction offset.

(25) More particularly, referring to FIGS. 7A and 7B, when disturbance A is generated as illustrated in FIG. 7A, a value, other than 0, is obtained as the corrective offset.

(26) Accordingly, as illustrated in FIG. 7B, the offset correcting unit 50 improves accuracy in estimating a frequency by adding the calculated corrective offset to the measurement angle.

(27) That is, the offset correcting unit 50 improves accuracy in estimating a frequency by dividing the offset caused by disturbance by the total number of teeth 31, and then adding or subtracting the calculated offset to or from the measurement angle of each of the teeth 31.

(28) In the meantime, the frequency estimating unit 60 may estimate a frequency with improved accuracy through a signal including a result value in which the measurement angle is corrected with the calculated corrective offset when disturbance is generated.

(29) In the present invention, the case where the four teeth 31 are formed at the tone wheel 30 is described as an example, but the present invention is not essentially limited thereto, and a plurality of teeth 31 may be formed at the tone wheel 30 regardless of the number of teeth 31 as a matter of course.

(30) Hereinafter, a wheel speed pretreatment method S1 according to an exemplary embodiment of the present invention will be described with reference to FIG. 8.

(31) The wheel speed pretreatment method S1 according to the exemplary embodiment of the present invention may include detecting the teeth 31 of the tone wheel 30 by using the hall sensor and obtaining a measurement angle including an offset (S10), calculating a corrective offset when disturbance is generated (S20), correcting the measurement angle by using the calculated corrective offset (S30), and estimating a frequency based on the result value calculated in operation S30 (S40).

(32) In the detecting of the teeth 31 of the tone wheel 30 by using the hall sensor and the obtaining of the measurement angle including the offset (S10), the teeth 31 of the tone wheel 30 are detected by using the hall sensor 40, and measurement angles X.sub.1, X.sub.2, X.sub.3, and X.sub.4 including the offset are detected as illustrated in FIG. 6.

(33) When the disturbance is generated, in the calculating of the corrective offset (S20), the corrective offset is calculated by Equation 1, in which the sum of the offsets is divided by the number of teeth. That is, a value, other than 0, is obtained as the sum of the offset by disturbance. Accordingly, the corrective offset calculated by Equation 1 is obtained.

(34) In the correcting of the measurement angle by using the calculated corrective offset (S30), and the estimating of the frequency based on the result value calculated in operation S30 (S40), the measurement angle of each of the teeth 31 is corrected by using the calculated corrective offset, and accuracy in estimating a frequency is improved by using a result value calculated based on the correction.

(35) As described above, the exemplary embodiments have been described and illustrated in the drawings and the specification. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.