DE10123527B4 - Method and system for determining the absolute angular position of a tire or sidewall torsion sensor - Google Patents

Abstract

A method of determining an absolute angular position of a tire (10) by means of a sidewall torsion sensor, comprising the steps of:
Measuring the phase position of the tire (10) by the sidewall torsion sensor,
- Measuring the phase angle of the tire (10) associated rim (12) and
Determining the absolute phase position of the tire (10) with the measured phase position of the tire (10) and the measured phase position of the rim (12),
characterized,
- That the measured phase position of the tire (10) is compared with the measured phase angle of the rim (12) and thereby the absolute angular position of the tire (10) is determined, and
- That the measured phase angle of the tire (10) is corrected taking into account the absolute angular position of the tire (10).

Description

The The invention relates to a method for determining the absolute angular position a tire by means of a sidewall torsion sensor with the steps: Measuring the phase angle of the tire by the sidewall torsion sensor and measuring the phase angle of a rim associated with the tire and determining the absolute phase of the tire with the measured phase angle the tire and the measured phase angle of the rim. The invention relates a system for determining the absolute angular position of a Sidewall torsion sensor on a tire with means for measuring the phase angle of the tire through the sidewall torsion sensor and Means for measuring the phase position of a tire associated Rim and means for determining the absolute angular position of Tire from the measured phase of the tire and the measured Phase of the rim.

Seitenwandtorsionssensoren come in particular to the use of a wheel and a Transferring tires to the road Moments or the current friction coefficients of tires evaluate the roadway. For this purpose it is known in the Sidewall of a tire a variety of permanent magnetic areas evenly over the to distribute the entire circumference of the tire. In particular, it is possible to permanent magnetic areas in the tire wall or store to apply to the tire wall. At a distance to the tire wall is arranged a transducer, the at least two in different Radial distance from the axis of rotation of the wheel arranged measuring elements having. The changes the magnetic fields due to the rotational movement of the tire call to the outputs The transducer signals out the rotational movement of the tire reflect. Does it now come to a deformation of the tire due the forces acting on the tire, respectively the transmitted Drive or braking torques, this causes a shift in the Phase angle between the output from the measuring elements measuring signals. Thus, this shift of the phase position as a measure of the transmitted Moments or for the instantaneous coefficients of friction are evaluated.

at Determining the phasing of a tire is problematic proved that the production of a homogeneous sinusoidal magnetization over the entire tire circumference with big Difficulties connected. There will therefore be correction procedures needed about these shortcomings to compensate for the magnetization. These consist for example in that one considers the magnetization of the tire in dependence measures the angular position and the relationship of these quantities in one Characteristic deposited. By consideration this characteristic can calculatively eliminates the disadvantages of imperfect magnetization become. However, it is to be considered This characteristic requires that the absolute angular position of the magnetized Tire is known, because only so the system is known which Use the position of the characteristic to determine the correction data is.

A method and a system of the type mentioned is based on DE 44 35 160 A1 out. WO 01/19656 A1 discloses an electronic evaluation unit for the measurement signals of a tire sensor, the measured values of two sensors being compared with one another. The DE 199 04 818 A1 relates to a sensor arrangement for a vehicle control system with a tire sensor. Measures are provided to determine and compensate for the phase relationship between the inner sensor and the outer sensor signal (wheel bearing sensor and strut sensor signal) to account for a shift of the tire on the rim.

Of the Invention is based on the object, an improved method or to create an improved system.

These Task is solved in the method that the measured phase angle of the tire is compared with the measured phase angle of the rim and thereby the absolute angular position of the tire is determined and taking into account the measured phase angle of the tire the absolute angular position of the tire is corrected. At the system is the solution the task provided with the means for determining the absolute Angular position the measured phase angle of the tire with the measured Phasing of the rim is compared and that in a functional element the measured phase of the tire taking into account the absolute Angular position of the tire is corrected. The measured phase position of the tire alone is not enough to the absolute angular position to investigate. However, in addition to the measured phase angle considering the rim, the absolute angular position of the tire is determined. This one will then for following correction methods used. The measured phase position the tire is taken into account the absolute angular position of the tire corrected. Thus, can the knowledge of the absolute angular position of the tire to an improved Determination of the phase position of the tire by a sidewall torsion sensor be used advantageously.

The method is particularly advantageous there in that the phase angle of the rim is measured by a pole wheel with N pole pairs or teeth and that the sidewall torsion sensor M has magnetic phases, where M ≠ N. In this way, the measuring signals of the sidewall torsion sensor with a different frequency than the measuring signals of the change Rim associated pole wheel. Consequently, it can be concluded by comparing the two measurement signals on the absolute angular position of the tire.

In In this context, it is particularly useful that the pole wheel for Measuring the phase angle of the rim belongs to an ABS speed sensor. ABS speed sensor are anyway provided on numerous vehicles, making it particularly economical is the signals of this speed sensor to determine the absolute Use angular position of the tire.

In a particularly preferred embodiment it is provided that the sidewall torsion sensor M magnetic Has phases, where | M-N | = 1. The number of magnetic phases the sidewall torsion sensor is thus different a phase of the number of magnetic phases of the ABS speed sensor. Consequently can be based on the absolute angular position of the tire by means of the vernier principle getting closed. In this case, the determination of the absolute angular position the more accurate, the larger the Number of pole pairs is. For example, a rotor of the ABS speed sensor is included 48 pole pairs and has the sidewall torsion sensor 47 magnetic Phases, the angular position can be measured with an accuracy of 360 ° / 48 become.

The method according to the invention is advantageously further developed in that, in the case of a tire fixedly connected to the rim, the phase Ph (rim) of the rim is determined by measuring a phase Ph (ImB) of a radially inner magnetized region of the tire and a phase Ph (λmB) of a radial outer magnetized area of the tire as Ph (rim) = k * (Ph (Amb) -ph (ImB)) where k is a tire constant. When the tire is firmly attached to the rim, the phase of the tire corresponds to the phase of the rim. If one now knows the phase position of the tire relative to the rim and the phase angle of the rim itself, which is firmly connected to the speed sensor, the absolute phase angle of the tire can be determined with the aid of the vernier principle.

It is of particular advantage when the measured phase angle of the tire is corrected in the knowledge of a characteristic that the magnetization of the tire in dependence the angular position of the tire contains. By knowing the absolute angular position of the tire, it is possible to measure a previously measured Characteristic curve showing the magnetization as a function of the angular position points to use.

The Invention builds on the generic system in that with the means for determining the absolute angular position the measured Phase of the tire compared with the measured phase angle of the rim and that in a functional element the measured phase angle of Tire under consideration the absolute angular position of the tire is corrected. In this way are the system of the invention the Advantages of the method according to the invention implemented. The measured phase angle of the tire is thus under consideration the absolute angular position of the tire corrected. Overall, therefore the determination of the phase position of the tire by a sidewall torsion sensor with higher accuracy.

Especially the system according to the invention is advantageous in that a Pole wheel with N pole pairs or teeth for measuring the phase angle the rim is provided and that the sidewall torsion sensor M magnetic phases, where M ≠ N. By comparing the With different frequencies oscillating measuring signals can be close to the absolute angular position of the tire.

in the Frame of the system according to the invention is it useful that the pole wheel for measuring the phase angle of the rim belongs to an ABS speed sensor. there it is a particularly economical solution since ABS speed sensor are provided in many vehicles anyway.

In a very preferred embodiment of inventive system this is designed so that the sidewall torsion sensor M magnetic Has phases, where | M-N | = 1. Since the number of magnetic Phases of the respective sensors thus by exactly one phase is different, can closed to the absolute angular position by means of the vernier principle become.

In the system of the present invention, it is preferable that, when the tire is fixed to the rim, the phase Ph (rim) of the rim is magnetized by measuring a phase Ph (ImB) of a radially inner magnetized region of the tire and a phase Ph (ÄmB) of a radially outer one Area of the tire as Ph (rim) = k * (Ph (Amb) -ph (ImB)) where k is a tire constant. at tire tightly connected to the rim corresponds to the phase of the tire of the phase of the rim. If one now knows the phase position of the tire relative to the rim and the phase angle of the rim itself, which is firmly connected to the speed sensor, the absolute phase angle of the tire can be determined with the aid of the vernier principle.

there It has proven to be particularly advantageous that the measured Phase of the tire is corrected in the knowledge of a characteristic, the magnetization of the tire as a function of the angular position of the tire. A previously measured characteristic gives tire-specific the dependence of the Magnetization from the angular position of the tire. Through this Knowledge and knowledge of the absolute angular position can be thus the accuracy of the determination of the phase position of the tire improve.

Of the Invention is based on the finding that the combination a sidewall torsion sensor and an ABS speed sensor the Absolute position of the sidewall torsion sensor can be determined. In particular, this is possible when the number of magnetic phases of the sidewall torsion sensor exactly one phase different from that of the ABS speed sensor. Under That is a requirement exact determination of the absolute position by means of the vernier principle possible.

drawings

The Invention will now be described with reference to the accompanying drawings preferred embodiments exemplified.

there shows:

1 a schematic representation of a portion of a wheel for explaining the determination of the phase angle of a tire;

2 several diagrams for explaining the vernier principle; and

3 a block diagram for explaining a system according to the invention.

description the embodiments

1 shows a schematic representation of a part of a wheel for explaining the determination of the phase position of a tire. On a rim 12 is a tire 10 arranged. This tire 10 has differently magnetized permanent magnetic areas 14 . 16 . 18 on, which are arranged alternately in their polarity. For example, the area 14 the north pole of a magnet, the area 16 is the South Pole, the area 18 again the North Pole, etc. The tire 10 is in 1 shown in a twisted state, that is, the tire areas substantially in the circumferential direction of the tire 10 are shifted. Here are radially outer regions of the tire 10 more displaced than more inward areas, ie those closer to the rim 12 lie. If one then applies transducers to different radial positions, that is to say, for example, in the case of lines a and b, then it will be found that the tire deforms 10 as a result of the on the tire 10 acting forces or as a result of the transmitted drive or braking torques, a shift of the phase position between the output from the arranged at the lines a and b measuring elements measurement signals occurs. When firmly connected to the rim tire, the phase of the rim Ph (rim) (line c) results Ph (rim) = k * (Ph (Amb) -ph (ImB)), where Ph (λm B): phase of the outer magnetized region at the line a in 1 ;
Ph (ImB): Phase of the inner magnetized region at the line b in 1 ;
Ph (rim): Phase of the rim at the line c in 1 ;
k: tire constant.

Know the phase of the tire 10 regarding the rim 12 and the phasing of the rim 12 itself, which is firmly connected to the speed sensor of the ABS, so it can affect the absolute phase of the tire 10 getting closed.

In 2 It is explained how the absolute phase position of the tire can be determined from the mentioned quantities. 2 shows several diagrams for explaining the vernier principle used for this purpose. At the in 2 Diagrams shown are different sizes each applied as a function of the rotation angle φ of the wheel. 2a shows a sinusoidal or cosine-shaped function, which is assigned to the recording of measured values with N pole pairs. In the present case, N = 2. 2 B shows corresponding sinusoidal or cosinusoidal curves, which are correlated with N + 1 = 3 pole pairs. By forming the inverse function of the tangent (Arctan) one obtains the in 2c or in 2d shown functions, where 2c from the sinusoidal or cosinusoidal progressions in 2a emerges while 2d from the sinusoidal or cosinusoidal progressions according to 2 B evident. 2e illustrates how to subtract from the in 2c and in 2d Functions illustrated the absolute phase position can. Are the 2a and 2c For example, assigned to the pole of the ABS speed sensor and the 2 B and 2d according to the sidewall torsion sensor, so is based on 2e recognizable that exactly after a wheel rotation of φ = 360 ° a difference between the functions of 2c and the 2d from 0 ° mod 360 ° is present. This corresponds to a certain angular position of the sidewall torsion sensor. If a change in this absolute angular position now takes place, then the difference of 0 ° mod 360 ° is present at another wheel angle position, from which the absolute angular position of the sidewall torsion sensor emerges.

3 shows a block diagram for explaining a system according to the invention. First, the in 3 used symbols explained:
101 : Measuring the phase position with a sidewall torsion sensor.
102 : Measuring the phase position with an ABS pole wheel.
103 : Determining the absolute phase position with a vernier method.
104 Correcting the phase angle measured by the sidewall torsion sensor.
105 : Result of the determination of the absolute phase position in the functional element 103 ,
106 : Outputting the Improved Phasing of the Sidewall Twist Sensor.

In functional element 101 a phase angle is measured by a sidewall torsion sensor. This phase angle measured by the sidewall torsion sensor is intended to be functional 104 be corrected, for example via a characteristic that contains information about the magnetic field as a function of the angular position. To make such a correction in functional element 104 To make reliable, it is necessary to know the absolute phase position. For this purpose is in functional element 102 the phase angle of an ABS pole wheel measured. The in functional element 101 and in functional element 102 measured phase positions are in functional element 103 combined by a vernier method. This provides the result 105 , namely the absolute phase angle. In functional element 104 Now, a correction is made from the measured phase position and the absolute phase position, for example via the characteristic, so that in functional element 106 the improved phase position can be output.

Claims (12)

Method for determining an absolute angular position of a tire ( 10 ) by means of a sidewall torsion sensor comprising the steps of: - measuring the phase position of the tire ( 10 ) through the sidewall torsion sensor, - measuring the phasing of the tire ( 10 ) associated rim ( 12 ) and - determining the absolute phase of the tire ( 10 ) with the measured phase angle of the tire ( 10 ) and the measured phase angle of the rim ( 12 ), characterized in that - the measured phase angle of the tire ( 10 ) with the measured phase angle of the rim ( 12 ) and thereby the absolute angular position of the tire ( 10 ), and - that the measured phase of the tire ( 10 ) taking into account the absolute angular position of the tire ( 10 ) is corrected. Method according to claim 1, characterized in that - the phase position of the rim ( 12 ) is measured by a pole wheel with N pole pairs or teeth, and that the sidewall torsion sensor M has magnetic phases, where M ≠ N. A method according to claim 2, characterized in that the pole wheel for measuring the phase position of the rim ( 12 ) belongs to an ABS speed sensor. Method according to one of the preceding claims, characterized in that the sidewall torsion sensor M is magnetic Has phases, where | M-N | = 1. Method according to one of the preceding claims, characterized in that when fixed to the rim ( 12 ) connected tire ( 10 ) the phase Ph (rim) of the rim ( 12 by measuring a phase Ph (ImB) of a radially inner magnetized region of the tire (FIG. 10 ) and a phase Ph (ÄmB) of a radially outer magnetized region of the tire ( 10 ) when Ph (rim) = k * (Ph (Amb) -ph (ImB)), where k is a tire constant. Method according to one of the preceding claims, characterized in that the measured phase position of the tire ( 10 ) is corrected in the knowledge of a characteristic which determines the magnetisation of the tire ( 10 ) depending on the angular position of the tire ( 10 ) contains. System for determining the absolute angular position of a sidewall torsion sensor on a tire ( 10 ) with means for measuring the phase angle of the tire ( 10 by the sidewall torsion sensor, means for measuring the phase angle of a tire ( 10 ) associated rim ( 12 ) and means for determining the absolute angular position of the tire ( 10 ) from the measured phase position of the tire ( 10 ) and the measured phase angle of the rim ( 12 ), characterized in that, with the means for determining the absolute angular position, the measured phase position of the tire ( 10 ) with the measured phase angle of the rim ( 12 ), and - that in a functional element ( 104 ) the measured phase angle of the tire ( 10 ) taking into account the absolute angular position of the tire ( 10 ) is corrected. System according to claim 7, characterized in that - a pole wheel with M Polpaaren or teeth for measuring the phase angle of the rim ( 12 ) and that the sidewall torsion sensor M has magnetic phases, wherein M ≠ N. System according to claim 8, characterized in that the pole wheel for measuring the phase position of the rim ( 12 ) belongs to an ABS speed sensor. System according to one of claims 7 to 9, characterized in that the sidewall torsion sensor M has magnetic phases, where | M-N | = 1. System according to one of claims 7 to 10, characterized in that when fixed to the rim ( 12 ) connected tire ( 10 ) the phase Ph (rim) of the rim ( 12 by measuring a phase Ph (ImB) of a radially inner magnetized region of the tire (FIG. 10 ) and a phase Ph (ÄmB) of a radially outer magnetized region of the tire ( 10 ) when Ph (rim) = k * (Ph (Amb) -ph (ImB)), where k is a tire constant. System according to one of claims 7 to 11, characterized in that the measured phase position of the tire ( 10 ) is corrected in the knowledge of a characteristic which determines the magnetisation of the tire ( 10 ) depending on the angular position of the tire ( 10 ) contains.