DE102010006178B4 - Method for monitoring a tire pressure and tire pressure monitoring device - Google Patents

Abstract

Device (32) for checking tire pressures of front wheels (Rad3, Rad4) and rear wheels (Rad1, Rad2) of a vehicle, the device comprising: - an interface device (34) for receiving signals from sensor devices (20) of the vehicle wheels (14, 14; Rad1, Rad2, Rad3, Rad4) which directly or indirectly detect the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels (14, Rad1, Rad2, Rad3, Rad4), - a memory device (38) for storing a setpoint Tire diameter (rd0) of a target wheel (Rad0) of the vehicle at a reference point (m), - an angular velocity determining means (40) for determining the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels based on the measurement results of the sensor devices of the vehicle wheels, and - an evaluation device (36) having at least one error quantity (err12, err13, err14, err23, err24, err34) based on the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels and the S Determined oll-tire diameter (rd0) of the target wheel, the evaluation device (34) determines based on the error size, if at least one of the vehicle wheels has a faulty tire pressure, characterized in that the evaluation device (36) is adapted to by a comparison of four vehicle wheels with each other to determine a deviation of the angular velocity (ω1, ω2, ω3, ω4) of the vehicle wheels from an expectation value based on the target tire diameter (rd0) of the target wheel.

Description

The invention relates to a method for detecting a pressure loss of a tire in a vehicle equipped with a tire pressure monitoring unit. The invention further relates to a tire pressure control unit, a vehicle and a computer product program.

Since vehicle safety and reliability are key factors in automotive technology, it is only for safety reasons that the tire pressure of motor vehicles has to be checked regularly. Since this is often neglected, modern motor vehicles increasingly have tire pressure monitoring systems which automatically measure the tire pressure and detect a critical deviation of the measured tire pressure from a tire pressure setpoint at an early stage. In addition, to reduce CO ₂ emissions, it is desirable to monitor tire pressure on as many vehicles as possible.

In such tire pressure monitoring systems, a distinction is generally made between direct and indirect systems. Indirect systems do not measure the tire pressure itself, but use a derived from the tire pressure size, for example, the speed of the tire, such as in the DE 195 32 331 A1 is disclosed. For direct systems, such as in the DE 43 03 583 A1 , inside the tire or on its valve, a sensor is attached, which transmits by radio transmission at certain intervals the internal pressure and / or the temperature of the tire to a central system. The driver receives information about the current pressure value in plain text, which he either sees constantly in the display, or can query by pressing a button.

From US 2003/0172 728 A1 a method, a computer program product and a device for estimating the air pressure of a tire on a vehicle are known, comprising the steps of: receiving a vehicle status sensor signal as an input; Estimating first parameter values of an adaptive filter based on a predetermined model of vehicle status in response to the vehicle status sensor signal; Calculating, based on the first model parameter values, a first tire pressure indication value that is dependent on and characterizes the tire air pressure.

From the DE 10 2006 020 490 A1 For example, a method is known for accurately determining the circumference of a wheel of a vehicle having at least two wheels. In this case, the exact circumference of a first wheel of the vehicle is determined depending on a yaw rate of the vehicle, a first rotational speed of the first wheel, a second rotational speed of the second wheel and a track between the first wheel and the second wheel.

From the DE 100 24 178 A1 is a method for improved determination of the ratio of the radii of the wheels (also called wheel radius ratio) of a vehicle to each other known. Such Radradienverhältnisse can be used, for example, to detect an impermissible tire pressure.

At one of the US 5 826 207 A known tire air pressure estimation based on vibration components extracted from a vehicle wheel speed signal when the vehicle wheel is a driven vehicle wheel, the accuracy of the estimation is improved by removing the vibration components due to the resonance of the drive system from the vibration components on the basis of which the estimation calculation is performed , The vibration components due to the resonance of the drive system can be removed by removing those vibration components extracted from the vehicle wheel speed signal which are equal in phase between left and right driven vehicle wheels. When the tire air pressure of one of a pair of left and right driven vehicle wheels is lower than the other, the lower tire inflation pressure is more properly estimated. Therefore, the higher tire air pressure may be estimated based on the lower tire air pressure versus the drive system resonance.

US 2006/0 267 750 A1 describes a control system for controlling a motor vehicle. Various tire parameters, such as a rolling radius, a vertical spring rate and a tire torsional spring rate, may be used to determine a tire abnormality condition. The vehicle is controlled in response to the tire abnormality condition.

US 2009/0 112 470 A1 provides a navigation device with a central processing unit, an imaging module, a GPS module, a tire pressure monitoring module and a memory module. The imaging module captures an image signal. The central processing unit controls the imaging module to acquire the image signal for generating image data, and further stores the image data in the memory module. The central processing unit executes the electronic map software stored in the memory module and receives the position data generated by the GPS module to generate route guidance. The central processing unit receives that from the Tire pressure monitoring module received digital tire pressure signal to generate tire pressure data, and also identifies whether the tire pressure data corresponds to a safety value or not.

The object of the invention is to provide an improved tire pressure monitoring device for the aforementioned system.

This object is achieved by a device having the features of patent claim 1 and a method having the features of patent claim 9.

• - eine Schnittstellen-Empfangseinrichtung zum Empfangen von Signalen von Sensoreinrichtungen der Fahrzeugräder, welche direkt oder indirekt die Winkelgeschwindigkeiten der Fahrzeugräder erfassen,
• - eine Speichereinrichtung zum Speichern eines Soll-Reifendurchmessers eines Soll-Rads des Fahrzeugs in einem Referenzpunkt, eines Längenabstands der Vorderräder von den Hinterräder und eines Breitenabstands der Vorderräder und/oder Hinterräder voneinander;
• - eine Winkelgeschwindigkeits-Bestimmungseinrichtung zum Bestimmen der Winkelgeschwindigkeiten der Fahrzeugräder auf Basis der Messergebnisse der Sensoreinrichtungen der Fahrzeugräder, und
• - eine Auswerteeinrichtung, welche wenigstens eine Fehlergröße auf Basis der Winkelgeschwindigkeiten der Fahrzeugräder und des Soll-Reifendurchmessers des Soll-Rads berechnet, wobei die Auswerteeinrichtung anhand der Fehlergröße bestimmt, ob wenigstens eines der Fahrzeugräder einen fehlerhaften Reifendruck aufweist, wenn die Fehlergröße kleiner und/oder größer als Null ist, wobei die Auswerteeinrichtung dazu eingerichtet ist, durch einen Vergleich von vier Fahrzeugrädern untereinander eine Abweichung der Winkelgeschwindigkeit der Fahrzeugräder von einem Erwartungswert, der auf dem Soll-Reifendurchmesser des Soll-Rades basiert, zu ermitteln.

Accordingly, the invention provides an apparatus for checking tire pressures of front wheels and rear wheels of a vehicle, the apparatus comprising:

• an interface receiving device for receiving signals from sensor devices of the vehicle wheels which directly or indirectly detect the angular speeds of the vehicle wheels,
• a memory means for storing a target tire diameter of a target wheel of the vehicle at a reference point, a longitudinal distance of the front wheels from the rear wheels and a width distance of the front wheels and / or rear wheels from each other;
• an angular velocity determining means for determining the angular velocities of the vehicle wheels on the basis of the measurement results of the sensor devices of the vehicle wheels, and
• an evaluation device which calculates at least one error variable on the basis of the angular velocities of the vehicle wheels and the nominal tire diameter of the reference wheel, the evaluation device determining on the basis of the error variable whether at least one of the vehicle wheels has an incorrect tire pressure, if the error variable is smaller and / or is greater than zero, wherein the evaluation device is adapted to determine by a comparison of four vehicle wheels with each other, a deviation of the angular velocity of the vehicle wheels of an expected value based on the target tire diameter of the target wheel.

The device has the advantage that it can very easily and reliably detect a faulty tire pressure and can rely on existing sensor devices in the vehicle, the signals of which they can detect via the receiving device. For example, signals from piezo sensors, wheel sensors in the wheels or signals from an ABS system can be used.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims and the description with reference to the drawings.

• 1 eine Draufsicht auf ein Fahrzeug mit einer Reifendrucküberwachungseinrichtung gemäß einer ersten Ausführungsform der Erfindung;
• 2 eine Draufsicht auf ein Fahrzeug mit einer Reifendrucküberwachungseinrichtung gemäß einer zweiten Ausführungsform der Erfindung;
• 3a eine schematische Ansicht eines Fahrzeugs mit vier zu überwachenden Rädern, wobei sich das Fahrzeug im Kreis um einen Mittelpunkt M bewegt wird;
• 3b eine schematische Ansicht des Fahrzeugs gemäß 3a, wobei als Referenzpunkt m der Mittelpunkt zwischen den beiden Achsen des Fahrzeugs gewählt ist, der aus dem Schnittpunkt der Achsenkreuzlinien gebildet wird;
• 3c eine schematische Ansicht des Fahrzeugs gemäß 3a, wobei als Referenzpunkt m der Schnittpunkt der Flächendiagonale des Fahrzeugs bestimmt wird;
• 4 ein Ablaufdiagramm einer Reifendrucküberwachung gemäß einer Ausführungsform der Erfindung;
• 5 ein Ablaufdiagramm einer Reifendrucküberwachung gemäß einer weiteren Ausführungsform der Erfindung;
• 6 ein Beispiel eines Algorithmus zur Reifendrucküberwachung gemäß der Erfindung;
• 7 ein Ablaufdiagramm zur Bestimmung der Geschwindigkeitskomponenten Vx und Vy des Fahrzeugs; und
• 8 eine Vorrichtung gemäß einer Ausführungsform der Erfindung zum Bestimmen, ob eines der Fahrzeugräder einen fehlerhaften Reifendruck aufweist.

The invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures of the drawings. Show it:

• 1 a plan view of a vehicle with a tire pressure monitoring device according to a first embodiment of the invention;
• 2 a plan view of a vehicle with a tire pressure monitoring device according to a second embodiment of the invention;
• 3a a schematic view of a vehicle with four wheels to be monitored, wherein the vehicle is moved in a circle about a center M;
• 3b a schematic view of the vehicle according to 3a , wherein as reference point m, the center between the two axes of the vehicle is selected, which is formed from the intersection of the Achsenkreuzlinien;
• 3c a schematic view of the vehicle according to 3a , where as the reference point m, the intersection of the surface diagonal of the vehicle is determined;
• 4 a flowchart of a tire pressure monitoring according to an embodiment of the invention;
• 5 a flowchart of a tire pressure monitoring according to another embodiment of the invention;
• 6 an example of a tire pressure monitoring algorithm according to the invention;
• 7 a flow chart for determining the speed components Vx and Vy of the vehicle; and
• 8th a device according to an embodiment of the invention for determining whether one of the vehicle wheels has a faulty tire pressure.

In all figures, identical or functionally identical elements and devices have been provided with the same reference numerals, unless stated otherwise.

In the following, a method according to the invention and a device according to the invention for tire pressure monitoring will be described, wherein the tire pressure monitoring can be integrated, for example, in a retrofitted navigation device. In addition, the localization quality of the navigation system can additionally be significantly improved, even if up to two tires have a tire vacuum and / or a tire overpressure.

Essentially, there are three system approaches for tire pressure monitoring:

In the first approach, the tire pressure is measured by sensors installed in the rim, which transmit their measurement result via radio to a control unit installed in the vehicle. The control unit evaluates the results of all sensors and displays them. However, the control unit can not be retrofitted by the additional sensors.

A second approach is to evaluate the data from wheel sensors typically used for ABS controllers to conclude air pressure loss on the faster rotating wheel by comparing the rotational or angular speeds of the wheels on an axle or by cross comparison can. However, the method may u.U. No very high accuracy to reliably locate a defective tire.

In the third approach piezoelectric sensors are used. These provide the centrifugal force and / or the amplitude of the sensor acceleration, which results in the reduction of the tire diameter when the tire touches down on the road and lifts off again. On the basis of the measured values, it is again possible to deduce the tire pressure.

For the localization of the tires, there are further essentially the following methods:

According to the first method, the tire has a coded transmitter, which must be communicated to the tire pressure system with the appropriate position during assembly of the tire. This process is necessary every time the tires are reassembled, for example when changing between summer and winter tires.

The second method relies on the tire electronics being moved over a position-related interface, e.g. 125kHz interface, can be addressed individually. The separate antennas are installed in the wheel arches and thus only the addressed tire responds and delivers its current measured value.

In the third method, the localization of the respective wheel takes place by a cross comparison of the speeds of the four wheels with each other. But this is only possible if at most one tire is defective.

In 1 is a top view of a vehicle 10 illustrated with a tire pressure monitoring device according to a first embodiment of the invention. The vehicle 10 here has a front axle 12 with two wheels 14 and a rear axle 16 with two wheels 14 on. The vehicle further includes, for example, an ABS (Anti-lock Braking System) device 18 , In such an ABS device 18 is at each of the wheels 14 at least one rotational speed sensor device 20 provided with the speed or angular velocity of the respective wheel 14 is determined. The ABS facility 18 is also for example via a CAN bus device 22 with the rear wheel axle 16 connected or with the speed sensor devices 20 the two rear wheels 14 and receives over the bus facility 22 the respective wheel pulses or the measurement results of the individual speed sensor devices 20 ,

Furthermore, the vehicle is equipped, for example, with a retrofitted electronic component with radio receiver, preferably a navigation device. According to the invention, a radio interface is further provided, via which data from sensor devices, such as speed sensor devices, can be transmitted from the vehicle to the radio receiver, as in 1 is shown.

According to the first embodiment of the invention, the measurement results of the rotational speed sensor devices are transmitted 20 the wheels 14 ie here, for example, the wheel speeds or angular speeds of the wheels 14 , to a navigation system 24 , being as interface 26 For example, a Bluetooth interface is used. The navigation system with the interface, here the example Bluetooth or CAN interface, can very easily in a vehicle 10 be retrofitted or already installed in the vehicle.

In 2 A second embodiment of the invention is also a vehicle 10 shown in a plan view. The vehicle also points to the front wheel axle 12 two wheels 14 and on the rear wheel axle 16 two wheels 14 on. Each of the wheels 14 is here with a piezo sensor device 20 Mistake. The piezo sensor devices 20 determine, for example, the acceleration or centrifugal force or the speed or angular velocity of the respective wheel 14 , These transmit their measurement results, for example via an interface 26 such as a radio interface to a navigation system 24 , The measurement results can be transmitted at regular or irregular intervals. The navigation system 24 with the radio interface 26 can do this on the vehicle 10 be retrofitted or already installed in the vehicle.

For both vehicles 10 equipped according to the first or second embodiment of the invention, the retrofitted navigation system can issue a tire pressure warning, and locate up to two defective tires.

According to the invention, in these cases, for example, a deviation of the angular velocity of a wheel by comparing all four wheels with each other ("overdetermined system") recognized and concluded on the tire diameter and the tire pressure of the vehicle. Based on a comparison with a corresponding desired size such as a desired tire diameter can be concluded from whether the vehicle has a desired desired tire pressure or a negative or positive pressure. If the determined deviation exceeds or falls below a limit value or limit range, a warning about excessively high or too low tire pressure can be output to the driver.

In particular, the evaluation of the overdetermined system according to the invention also makes it possible to locate the defective wheel (s) with the faulty air pressure. Thus, the data may be used for the location of the defective wheel when the tire pressure is monitored in parallel via an electronics installed in the rim or in the wheel, for example via speed sensor devices according to the first embodiment or via piezo sensor devices according to the second embodiment of the invention.

In the 3a . 3b and 3c is a schematic view of a vehicle 10 as well as its geometry relationships during cornering. As in 3a is shown drives the vehicle 10 with his four wheels 14 respectively. wheel1 . Rad2 . Wheel 3 and Rad4 here in an imaginary circle around a center M. The four wheels wheel1 . Rad2 . Wheel 3 and Rad4 each have a distance or radius D1 . D2 . D3 and D4 to the center M on. Furthermore, the distance between the front wheels Rad4 and Wheel 3 or the front wheel axle to the rear wheels wheel1 and Rad2 or the rear wheel axle as a distance 1 Are defined. The distance between the two front wheels Wheel 3 and Rad4 or the distance between the two back wheels wheel1 and Rad2 is defined as the distance b.

Furthermore, next to the wheels wheel1 . Rad2 . Wheel 3 and Rad4 a target wheel RAD0 assumed that is located at a reference point m, for example, in the center m between the two axes of the vehicle, formed from the intersection of the Achsenkreuzlinien 30 , as in 3b is shown.

However, other reference points m on the vehicle may also be used, for example the intersection of the area diagonal of the vehicle, as in FIG 3c is shown. The following equations are for example based on a reference point m according to 3b created.

The target wheel has a distance or radius D0 to the center of the circle M and a speed V0 on which corresponds to the vehicle speed. The target wheel RAD0 has a predetermined target tire pressure and due to the predetermined desired target tire pressure a corresponding desired tire diameter rd0. According to the invention will now be the respective tire diameter rd1 . rd2 . rd3 , and r4d ( 3b and 3c) the four wheels wheel1 . Rad2 . Wheel 3 and Rad4 of the vehicle. If the diameter rdx of one of the wheels Radx (x = 1, 2, 3 or 4) is smaller than the target wheel diameter RD0 of the target wheel RAD0 or is smaller than a predetermined target range for the target wheel diameter RD0 , it can be concluded that the wheel has too low a tire pressure. Accordingly, if the diameter rdx of one of the wheels Radx (x = 1, 2, 3 or 4) is greater than the target wheel diameter RD0 of the target wheel RAD0 is or greater than a predetermined target range for the target wheel diameter RD0 is, it can be concluded that the Radx has too high a tire pressure.

In the in 3a Cartesian coordinate system shown points the speed V0 of the wheel RAD0 or of the vehicle, a velocity component Vx in the X direction and a velocity component Vy in the Y direction. Instead of a Cartesian coordinate system but any other coordinate system can be used, for example, a polar coordinate system.

$$D{2}^2+l^2=D{4}^2$$

$$D2-D1=b$$

$${\left(D1+\frac{b}{2}\right)}^2+{\left(\frac{l}{2}\right)}^2=D{0}^2$$

$${\left(D2+\frac{b}{2}\right)}^2+{\left(\frac{l}{2}\right)}^2=D{0}^2$$

$$rd1\cdot \omega 1=2\cdot D1\cdot \mathrm{\Omega 0}$$

$$rd2\cdot \omega 2=2\cdot D2\cdot \mathrm{\Omega 0}$$

$$rd3\cdot \omega 3=2\cdot D3\cdot \mathrm{\Omega 0}$$

$$rd4\cdot \omega 4=2\cdot D4\cdot \mathrm{\Omega 0}$$

$$rd0\cdot \omega 0=2\cdot D0\cdot \mathrm{\Omega 0}$$

$$\omega 0\cong \frac{\left(\omega 1+\omega 2+\omega 3+\omega 4\right)}{4}$$

Based on the geometry relationships of the tires of the vehicle during cornering, the above-mentioned overdetermined system of equations can now be described as follows: $$\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}{1}^2+{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">D</figure-callout>}{3}^2$$

$$\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">D</figure-callout>}{2}^2+{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=D{4}^2$$

$$D2-\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1=b$$

$${\left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1+\frac{b}{2}\right)}^2+{\left(\frac{l}{2}\right)}^2=\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}{0}^2$$

$${\left(\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">D</figure-callout>}2+\frac{b}{2}\right)}^2+{\left(\frac{l}{2}\right)}^2=\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}{0}^2$$

$$r\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">d</figure-callout>}1\cdot \mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1=2\cdot \mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1\cdot \mathrm{\Omega 0}$$

$$r\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">d</figure-callout>}2\cdot \mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}2=2\cdot \mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">D</figure-callout>}2\cdot \mathrm{\Omega 0}$$

$$r\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">d</figure-callout>}3\cdot \mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}3=2\cdot \mathrm{<figure-callout\; id="3"\; label="D"\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">D</figure-callout>}3\cdot \mathrm{\Omega 0}$$

$$rd4\cdot \omega 4=2\cdot D4\cdot \mathrm{\Omega 0}$$

$$r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \mathrm{<figure-callout\; id="0"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\omega </figure-callout>}0=2\cdot \mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0\cdot \mathrm{\Omega 0}$$

$$\mathrm{<figure-callout\; id="0"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\omega </figure-callout>}0\cong \frac{\left(\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}2+\mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}3+\omega 4\right)}{4}$$

Legend:

D0

Radius of the wheel Rad0 or radius of the vehicle center m around the center of the circle M

Ω0

Angular velocity of the vehicle center point m (here, for example, the vehicle center is taken as the reference point m, which is formed in this case by the intersection of the axis cross-lines of the vehicle, as in 3b shown)

D1

Radius of the first wheel Rad1 around the center of the circle M

D2

Radius of the second wheel Rad2 around the center of the circle M

D3

Radius of the third wheel Rad3 around the center of the circle M

D4

Radius of the fourth wheel Rad4 around the center of the circle M

ω1

Angular velocity of the first wheel Rad1

ω2

Angular velocity of the second wheel Rad2

ω3

Angular velocity of the third wheel Rad3

ω4

Angular velocity of the fourth wheel Rad4

RD0

nominal wheel diameter of the wheel Rad0, which has a predetermined, desired or sufficient air pressure

rd1

actual wheel diameter of the wheel Rad1, which has an actual air pressure

rd2

actual wheel diameter of the wheel Rad2, which has an actual air pressure

rd3

actual wheel diameter of the wheel Rad3, which has an actual air pressure

rd4

actual wheel diameter of the wheel Rad4, which has an actual air pressure

$$D0=\frac{rd0\cdot \omega 0}{2\cdot \mathrm{\Omega 0}}$$

Calculation of the radius D0 the target wheel RAD0 or the vehicle center m (here reference point m) and the angular velocity Ω0 of the target wheel RAD0 or the vehicle center m (here reference point m): $$\mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0=\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0}{2}\cdot \sqrt{\frac{\mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}{3}^2+\omega 4^2-2<figure-callout\; id="1"\; label="\cdot \; \omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\cdot \; </figure-callout>\omega 1\cdot \mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}2}{2\cdot {\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">b</figure-callout>}}^2}}$$

$$\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0=\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0\cdot \mathrm{<figure-callout\; id="0"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\omega </figure-callout>}0}{2\cdot \mathrm{\Omega 0}}$$

$$Vx=\frac{V0}{D0}\cdot \left(D1+\frac{b}{2}\right)$$

$$Vy=\frac{V0}{D0}\cdot \frac{l}{2}$$

From this, the vehicle speed is calculated V0 and thus the speed of the target wheel RAD0 around the center point M and the two velocity vectors Vx and Vy as follows: $$\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">V</figure-callout>}0=2\cdot \pi \cdot \mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0$$

$$Vx=\frac{V0}{\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0}\cdot \left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1+\frac{b}{2}\right)$$

$$Vy=\frac{V0}{\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0}\cdot \frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}{2}$$

In order to determine whether the radius rdx of the wheel Radx (x = 1, 2, 3, 4) is of the predetermined sufficient radius RD0 of the fictitious target wheel RAD0 deviates or not, for example, at least one, two or all three of the following variables err13, err24 and err12 are used. With these three sizes, all four wheels can wheel1 . Rad2 . Wheel 3 and Rad4 be covered or recorded:

Function (A) for the first wheel wheel1 and the third wheel Wheel 3 to determine the size err13: $${\left(\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0}{2\cdot \mathrm{\Omega }\text{0}}\right)}^2\cdot \left(\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}{1}^2-\mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}{3}^2\right)-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=err13$$

Function (B) for the second wheel Rad2 and the fourth wheel Rad4 to determine the size err24: $${\left(\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0}{2\cdot \mathrm{\Omega }\text{0}}\right)}^2\cdot \left(\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}{2}^2-\omega 4^2\right)-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=\mathrm{<figure-callout\; id="24"\; label="e\; r\; r"\; filenames="DE102010006178B4\_0038.png"\; state="\{\{state\}\}">e\; </figure-callout>}rr24$$

Function (C) for the first wheel wheel1 and the second wheel Rad2 to determine the size err12 or err21: $$\left(\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0}{2\cdot \mathrm{\Omega }\text{0}}\right)\cdot \left(\omega 2-\omega 1\right)-b=err21$$

$$err24-err13=err21-err43$$

The quantities err14, err34, err23 are combinations of err21, err13, err24 and can be determined accordingly. $$err13+\mathrm{<figure-callout\; id="24"\; label="e\; r\; r"\; filenames="DE102010006178B4\_0038.png"\; state="\{\{state\}\}">e\; </figure-callout>}rr24=\mathrm{<figure-callout\; id="14"\; label="e\; r\; r"\; filenames="DE102010006178B4\_0038.png,DE102010006178B4\_0040.png"\; state="\{\{state\}\}">e\; </figure-callout>}rr14+err23+{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2$$

$$err24-err13=err21-err43$$

In this case, a function (D) for the first wheel applies wheel1 and the fourth wheel Rad4 For example, to determine the size err14 is:
starting from err13 + err24 = err14 + err23 + l ² $$e\mathrm{<figure-callout\; id="14"\; label="r\; r"\; filenames="DE102010006178B4\_0038.png,DE102010006178B4\_0040.png"\; state="\{\{state\}\}">r\; </figure-callout>}r14=err13+err24-err23-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2$$

The function (E) for the second wheel Rad2 and the third wheel Wheel 3 for example, to determine the size err23 is:
starting from err13 + err24 = err14 + err23 + l ² $$err23=err13+err24-err14-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2$$

The function (F) for the third wheel Wheel 3 and the fourth wheel Rad4 to determine the size err34 is:
from err24-err13 = err21-err43 $$err43=err13+err21-\mathrm{<figure-callout\; id="24"\; label="e\; r\; r"\; filenames="DE102010006178B4\_0038.png"\; state="\{\{state\}\}">e\; </figure-callout>}rr24$$

Also other sizes, eg err14, err34 or err23 (functions D, E and F) can be selected. However, only three linearly independent quantities err _xy (X, Y = 1, 2, 3, 4) are possible.

In 4 A flow chart is now shown for determining whether a tire has too low a tire pressure. In this case, the above three functional examples (A) to (C) are used, covering all four wheels of the vehicle.

In a first step S1 becomes a target wheel diameter RD0 given, the distance 1 the front wheels to the rear wheels or their axes, the distance b of the rear wheels or front wheels from each other. Furthermore, in a next step S2 the angular velocities ω1, ω2, ω3 and ω4 of the four wheels wheel1 . Rad2 . Wheel 3 and Rad4 directly or indirectly determined by means provided in the vehicle sensor devices, such as wheel sensor devices and / or piezo sensor devices, for example, an ABS system of the vehicle. The invention is not limited to these examples of sensor devices. In principle, any other sensor device or combination of sensor devices can be used which is suitable for directly or indirectly determining the angular velocity of the respective vehicle wheel. This will be the next step S3 the angular velocity Ω0 of the target wheel RAD0 in the vehicle center m as well as the radius D0 of the target wheel RAD0 calculated. In a subsequent step S4 then the quantities err13, err24 and err12 are determined by the functions (A), (B) and (C). In a further step S5 it is determined whether the quantities err12, err24 and err13 are less than or equal to a setpoint, here zero. Besides the nominal value, here zero, as in the examples in 4 and 5 is shown, optionally also an additional tolerance range for the desired value can be specified (not shown). In this case, the specified range is a range which includes values below and / or above the setpoint or here zero.

From comparing the sizes in step S5 can step out of it S6 be closed, whether a wheel diameter rdx a wheel Radx has too low a tire pressure or the desired desired tire pressure. Will in step S6 found that rd1 <rd0, so the wheel points wheel1 too low a tire pressure. The same applies if rd2 <rd0 or err _xy <0, then the wheel points Rad2 too low a tire pressure. Likewise, the wheel points Wheel 3 too low tire pressure if rd3 <rd0 applies. This also applies to the bike Rad4 , This has too low a tire pressure if rd4 <rd0 applies.

In the case that err12, err24 and err13 are all zero or equal to the set point or within the tolerance range for the set point, all four wheels point wheel1 . Rad2 . Wheel 3 and Rad4 the target tire pressure.

However, in the case of err12 <0, err24 <0 and err13 <0, more than one of the wheels has erroneous tire pressure. Likewise, at least two wheels have a faulty tire pressure when err12 = 0, err24 <0 and err13 <0. This also applies if err12 <0, err24 = 0 and err13 = 0. In this case also have at least two wheels on a faulty tire pressure. Also for all other cases, for example, the case err12 <0, err24 = 0 and err13> 0 applies, which are not shown in the boxes, at least one wheel has a faulty tire pressure. In total there are 3 ³ = 27 possible cases.

In 4 and later 5 16 of these are presented. In the 4 and 5 Cases not listed represent an error case, ie at least one wheel has a faulty tire pressure, without an unambiguous assignment or localization succeeds. This means that there is either a measurement error or more than one wheel deviates from the nominal diameter RD0 from. Preferably, a tire pressure warning will be output in each of these cases.

For example, by using only the three functions (A), (B) and (C) in step S4 and S5 can be concluded in the three cases only from the fact that at least two of the four wheels obviously have a faulty tire pressure.

In 5 is one too 4 corresponding flowchart shown. The flowchart in 5 differs from the one in 4 essentially only by determining whether a wheel has too high a tire pressure. The remarks to 4 apply accordingly also for 5 and will not be repeated.

Of course, it can also be determined at the same time whether a vehicle wheel has too low or too high a tire pressure or the desired desired tire pressure. As described above, the two embodiments according to 4 and 5 or their step are summarized very easily. It will be in the steps S5 and S6 determines whether there is too high, too low or target tire pressure in the vehicle wheels.

In 6 Furthermore, an example of an algorithm is shown, which by comparing all four wheels with each other, a deviation of the angular velocity ω1, ω2, ω3 and ω4 of the wheels and thus the tire diameter rd1 . rd2 . rd3 and rd4 the wheels of an expected value or target value determined. In this algorithm, for example, the sizes err13, err24 and err12 are determined on the basis of the functions (A), (B) and (C) and therefrom on the tire pressure of a respective vehicle wheel wheel1 . Rad2 . Wheel 3 and Rad4 closed.

In a further embodiment of the invention, in addition to monitoring the tire pressure of the wheels, additional information can also be used to improve the navigation system.

In 7 a flow chart for determining the speed components Vx and Vy of the vehicle is shown.

For the improvement of the positioning accuracy of navigation devices, in particular in the case of the failure of the GPS signals e.g. in a tunnel, mostly the so-called wheel sensors are used. This is easily possible with permanently installed in the vehicle navigation systems, but not in a retrofit solution. In addition, a pressure differential between the tires of an axle produces a systematic error in the determination of the vehicle direction.

To improve, for example, a retrofitted navigation system according to the invention, the velocity vectors Vx and Vy of the wheel RAD0 or the vehicle determined using equations (12) and (13). The sizes 1 , b, D0, Ω0 ω1, ω2, ω3, ω4 and RD0 are already known because they were previously determined to determine the tire pressure of the wheels. The velocity vectors Vx and Vy determined from the algorithm can be used here for improving the coupling location of the retrofitted navigation system and / or for indicating the driving speed.

As in 7 is shown in the step S1 as before in the 4 and 5 , first the nominal tire diameter RD0 a reference wheel RAD0 , as well as the distance 1 and the distance b of the vehicle or its wheels specified. In the next step S2 the angular speeds of the wheels ω1, ω2, ω3, ω4 are determined via corresponding sensor devices, for example piezo sensor devices and / or wheel sensor devices. Subsequently, in step S3 the angular velocity Ω0 and the radius D0 the target wheel RAD0 certainly.

$$V0=2\cdot \pi \cdot D0\cdot \mathrm{\Omega }\text{0}$$

In step S4 * then the speed V0 the target wheel RAD0 determines which of the vehicle speed V0 corresponds, and for example the distance D1 of the wheel wheel1 from the center of the circle M. The speed V0 and the distance or radius D1 can be calculated by means of the equations (5) and (11) mentioned above. $$\begin{array}{l}r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1=2\cdot \mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1\cdot \mathrm{\Omega 0}\\ \text{respectively}\text{,}\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1=\frac{\mathrm{<figure-callout\; id="0"\; label="r\; d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">r\; </figure-callout>}d0\cdot \mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1}{2\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}\text{0}}\end{array}$$

$$\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">V</figure-callout>}0=2\cdot \pi \cdot \mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}\text{0}$$

$$Vy=\frac{V0}{D0}\cdot \frac{l}{2}$$

In the next step S5 *, the velocity components Vx and Vy are then determined from equations (12) and (13) above: $$Vx=\frac{V0}{\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0}\cdot \left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1+\frac{b}{2}\right)$$

$$Vy=\frac{V0}{\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}0}\cdot \frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}{2}$$

It should be noted that in equation (12) the velocity component Vx depends on the radius D1 is expressed. Vx can also be dependent on D2 . D3 . D4 and or D1 In this case, in step S4 *, it then becomes corresponding D2 . D3 . D4 and or D1 certainly.

The algorithm provides the velocity components or velocity vectors Vx and Vy in particular even if one or two of the wheels wheel1 . Rad2 . Wheel 3 and Rad4 has a deviation from the target air pressure. The calculation of the velocity vectors Vx and Vy can be carried out according to the invention, for example in the retrofitted electronic component, for example here the retrofitted navigation system.

$$D{2}^2+l^2=D{4}^2$$

$$D2-D1=b$$

$${\left(D1+\frac{b}{2}\right)}^2+{\left(\frac{1}{2}\right)}^2=D{0}^2$$

$$rd0\cdot \omega 1=2\cdot D1\cdot \mathrm{\Omega }0$$

$$rd0\cdot \omega 2=2\cdot D2\cdot \mathrm{\Omega }0$$

$$rd0\cdot \omega 3=2\cdot D3\cdot \mathrm{\Omega }0$$

$$rd0\cdot \omega 4=2\cdot D4\cdot \mathrm{\Omega }0$$

The accuracy of the velocity vectors Vx and Vy can also be further increased if in a second pass the equation with rdx <rd0 and rdx> RD0 ie, the equations where a deviation of the tire diameter rdx (x = 1, 2, 3, 4) of one of the wheels from the target tire diameter RD0 is to be removed from the following equation system (1) to (8). $$\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}{1}^2+{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">D</figure-callout>}{3}^2$$

$$\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">D</figure-callout>}{2}^2+{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">l</figure-callout>}}^2=D{4}^2$$

$$D2-\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1=b$$

$${\left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1+\frac{b}{2}\right)}^2+{\left(\frac{1}{2}\right)}^2=\mathrm{<figure-callout\; id="0"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">D</figure-callout>}{0}^2$$

$$r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1=2\cdot \mathrm{<figure-callout\; id="1"\; label="D"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">D</figure-callout>}1\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0$$

$$r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}2=2\cdot \mathrm{<figure-callout\; id="2"\; label="D"\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">D</figure-callout>}2\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0$$

$$r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}3=2\cdot \mathrm{<figure-callout\; id="3"\; label="D"\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">D</figure-callout>}3\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0$$

$$r\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">d</figure-callout>}0\cdot \omega 4=2\cdot D4\cdot \mathrm{<figure-callout\; id="0"\; label="\Omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0042.png"\; state="\{\{state\}\}">\Omega </figure-callout>}0$$

in Abweichung von Gleichung (10). Ebenso kann die Winkelgeschwindigkeit ω0 stattdessen auch mittels Gleichung (10) berechnet werden. Grundsätzlich kann aber auch auf eine Ersetzung, z.B. im vorliegenden Fall von ω4 durch ω0, verzichtet werden und mit der Winkelgeschwindigkeit ω4 weitergerechnet werden.For example, it is found that the fourth wheel Rad4 has a negative pressure or rd4 <rd0, for example, only the equations (1) to (7), which refer to the first wheel wheel1 , the second wheel Rad2 and the third wheel Wheel 3 be used for the calculation of the velocity components Vx and Vy. In equation (8) which refers to the fourth wheel Rad4 In this case, the angular velocity ω4 can be replaced by ω0, since this wheel Rad4 for example, has too low a tire pressure. In this case, the angular velocity ω0 can be calculated, for example, as an average of the angular velocities ω1, ω2 and ω3, ie $\omega 0=\frac{\mathrm{<figure-callout\; id="1"\; label="\omega "\; filenames="DE102010006178B4\_0041.png,DE102010006178B4\_0045.png"\; state="\{\{state\}\}">\omega </figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102010006178B4\_0044.png"\; state="\{\{state\}\}">\omega </figure-callout>}2+\mathrm{<figure-callout\; id="3"\; label="\omega "\; filenames="DE102010006178B4\_0041.png"\; state="\{\{state\}\}">\omega </figure-callout>}3}{3}.$

in deviation from equation (10). Likewise, the angular velocity ω0 may instead be calculated by means of equation (10). In principle, however, it is also possible to dispense with a replacement, for example in the present case of ω4 by ω0, and to continue with the angular velocity ω4.

In 8th is further a device 32 for checking tire pressures of vehicle wheels wheel1 . Rad2 . Wheel 3 and Rad4 according to an embodiment of the invention.

The device 32 has an interface device 34 for receiving signals from one or more sensor devices 42 the vehicle wheels of the vehicle. The respective sensor device 42 or combination of sensor devices 42 In this case, it is possible to directly or indirectly determine the angular velocity ωx of the respective vehicle wheel Radx or to detect corresponding measured values and via the interface device 34 to an angular velocity determining device 40 the device 32 transfer. For example, each of the vehicle wheels may include a wheel sensor as a sensor device 42 exhibit, which directly determines an angular velocity of the associated vehicle wheel and the measurement result via the interface device 34 to the angular velocity determination device 40 transfer. Alternatively or additionally, however, can also be applied to other sensor devices 42 be resorted to, for example, piezoelectric sensors, etc., from their measurement results, a respective angular velocity of a vehicle wheel in the angular velocity determining device 40 can be determined or estimated.

Furthermore, the device 32 a storage device 38 on, in which, for example, a target tire diameter RD0 a target wheel RAD0 of the vehicle is stored in at least one predetermined reference point m. In addition to the nominal tire diameter can also from the angular velocity determination device 40 certain angular velocities of the vehicle wheels in the storage device 38 be stored or this alternatively or additionally directly to the evaluation 36 to get redirected.

In the storage device 38 can as a reference point m at least one reference point m, for example, according to 3b or 3c be stored. Furthermore, in the memory device 38 For example, at least a part or all of the aforementioned equations (1) to (13) and at least one or more functions (for example, the above functions (A), (B), (C), (D), (E) and / or (F)) for the sizes err12, err13, err14, err23, err24 and / or err34. In addition to or instead of the aforementioned equations and functions, however, any other kind of equations and functions which are suitable for determining the quantities err12, err13, err14, err23, err24 and / or err34 may also be stored.

The device 32 now has an evaluation 36 in which angular velocities ω of the vehicle wheels are evaluated and wherein by means of suitable equations (eg at least one, several or all equations (1) to (13)) and eg at least one, two or three of the functions (A) to (F) at least one, two or three sizes errXY can be determined and evaluated. The sizes errXY and their functions are preferably selected so that all four wheels of the vehicle are covered here. Represents the evaluation device 36 determined that at least one size errXY deviates from a predetermined desired value or nominal range, it can be issued to the driver of the vehicle, for example, that a vehicle wheel has no predetermined setpoint tire pressure. This can be done by the device 32 to issue a corresponding message via a display (not shown) connected to it or coupled to it or a loudspeaker connected or coupled to it in the vehicle (not shown).

The device 32 can be designed as part of a navigation system or be coupled with this, the navigation system is a fixed or retrofit navigation system.

The interface device 34 the device 32 is for example a radio interface device, a wireless LAN interface device, an infrared interface device, a Bluetooth interface device, a wired interface device and / or a serial interface device, wherein the wired interface device in particular a CAN bus or a LIN bus.

The sensor devices 42 which their measurement results to the angular velocity determination device 40 forward at least one piezoelectric sensor device and / or a Radsensoreinrichtung or yaw rate sensor device, wherein preferably at least one of the sensor devices 42 Part of a vehicle tire is and / or part of an anti-lock braking system (ABS).

In addition to the aforementioned devices, the device 32 optionally additionally a velocity component determination device 44 which, for example, the velocity components Vx, Vy of the velocity V0 of the vehicle at the predetermined reference point m of the vehicle. The speed component device 44 can do this with the storage device 38 and / or the angular velocity determining means 40 be connected and based on, for example, the angular velocities of the vehicle wheels and, for example, based on one or more of the equations (1) to (13) from the memory device, the speed components of the speed V0 determine the vehicle.

By the invention described herein, it is possible to easily retrofit a tire pressure monitoring with localization of the defective wheel in a vehicle. Another advantage of the invention is that the specific location quality of a retrofitted navigation system can be improved by determining the velocity components Vx and Vy without investing in additional, specific hardware components.

Another advantage of the invention is that the velocity components Vx and Vy can be accurately calculated even if one of the wheels wheel1 . Rad2 . Wheel 3 and Rad4 are defective or have too large or too small tire pressure. Thus, when calculating the velocity components Vx and Vy, preferably only the vehicle wheels and their angular velocities ω are taken into account, which have a setpoint tire pressure. The sizes of vehicle tires having a defective tire pressure are preferably not taken into account. By evaluating the error functions (A), (B), (C), as well as the example in 6 specified calculation method, the position of a wheel with negative pressure or a possible overpressure of the wheel can be determined.

Although the present invention has been described above with reference to the preferred embodiments, it is not limited thereto, but modified in many ways.

Claims (13)

Device (32) for checking tire pressures of front wheels (Rad3, Rad4) and rear wheels (Rad1, Rad2) of a vehicle, the device comprising: - an interface device (34) for receiving signals from sensor devices (20) of the vehicle wheels (14, 14; Rad1, Rad2, Rad3, Rad4) which directly or indirectly detect the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels (14, Rad1, Rad2, Rad3, Rad4), - a memory device (38) for storing a setpoint Tire diameter (rd0) of a target wheel (Rad0) of the vehicle at a reference point (m), - angular velocity determining means (40) for determining the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels based on the measurement results of the sensor devices of the vehicle wheels, and - an evaluation device (36) having at least one error quantity (err12, err13, err14, err23, err24, err34) based on the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels and d it determines target tire diameter (rd0) of the target wheel, wherein the evaluation device (34) determines based on the error size, if at least one of the vehicle wheels has a faulty tire pressure, characterized in that the evaluation device (36) is adapted to, by a comparison of four vehicle wheels with each other to determine a deviation of the angular velocity (ω1, ω2, ω3, ω4) of the vehicle wheels of an expected value based on the target tire diameter (rd0) of the target wheel. Device after Claim 1 , characterized in that the interface device (34) comprises a radio interface device, a WLAN interface device, an infrared interface device, a Bluetooth interface device, a wired interface device and / or a serial interface device. Device, wherein the wired interface device is in particular a CAN bus or a LIN bus. Device after Claim 1 or 2 Characterized in that the sensor means (42) comprise at least one piezoelectric sensor device and / or a Radsensoreinrichtung or angular rate sensor means, preferably one of the sensor means is at least part of a vehicle tire and / or part of an anti-lock (ABS) system. Device after Claim 1 . 2 or 3 , characterized in that the device (32) is a navigation system or is coupled or connected thereto, wherein the navigation system is in particular a permanently installed navigation system or a retrofit navigation system. Device according to one of Claims 1 to 4 characterized in that the device (32) comprises velocity component determination means (44) which determines the velocity components (Vx, Vy) of the velocity (V0) of the vehicle at a reference point (m) of the vehicle. Device according to one of Claims 1 to 5 , characterized in that an error quantity (err12) is predetermined for every two vehicle wheels (Rad1, Rad2), the error variable (err12) being dependent on the angular speeds (ω1, ω2) of the two vehicle wheels (Rad1, Rad2) and the nominal tire diameter ( rd0) of the target wheel (Rad0) and preferably three error quantities (err12, err13, and err24) are given for every two vehicle wheels, the three error quantities (err12, err13, and err24) together representing all four vehicle wheels (Rad1, Rad2 , Rad3, Rad4) of the vehicle. Device according to one of Claims 1 to 5 , characterized in that the evaluation device (36) determines that at least one of the vehicle wheels has a faulty tire pressure when at least one error quantity (err12, err13, err24) is outside a tolerance range for the desired value or not equal to the target value, or all vehicle wheels one Set tire pressure if all error quantities (err12, err13, err24) are in the tolerance range for the setpoint or equal to the setpoint. Device according to one of Claims 1 to 6 , characterized in that the evaluation device (36) determines that a vehicle wheel has a faulty tire pressure when an error quantity outside the tolerance range for the Setpoint or not equal to the setpoint and the other two error variables are within the tolerance range for the setpoint or equal to the setpoint. Method for checking tire pressures of front wheels (14, Rad3, Rad4) and rear wheels (14, Rad1, Rad2) of a vehicle (10), the method comprising the steps of: - specifying a nominal tire diameter (rd0) of a desired wheel ( Rad0) of the vehicle (10) at a reference point (m), - determining the angular velocity (ω1, ω2, ω3, ω4) of the vehicle wheels (Rad1, Rad2, Rad3, Rad4), - determining at least one error quantity (err12, err13, err14 , err23, err24, err34) for at least two vehicle wheels on the basis of the angular velocities (ω1, ω2, ω3, ω4) of the vehicle wheels and a nominal tire diameter (rd0) of the target wheel, - determining that at least one of the vehicle wheels (14) has an erroneous tire pressure when the error quantity is outside a tolerance range for a target value or is not equal to the target value, characterized by the step of determining a deviation of the angular velocity (ω1, ω2, ω3, ω4) of the vehicle wheels vo n an expected value based on the target tire diameter (rd0) of the target wheel by comparing four vehicle wheels with each other. Method according to Claim 9 characterized in that the method further comprises the steps of: calculating an error quantity (err12) for every two vehicle wheels (Rad1, Rad2) in dependence on the angular velocity (ω1, ω2) of the respective vehicle wheel (Rad1, Rad2) and the target tire diameter (rd0) of the target wheel (Rad0) and preferably calculating three error quantities (err12, err13, and err24) for every two vehicle wheels, the three error quantities (err12, err13, and err24) together representing all four vehicle wheels (Rad1, Rad2, Rad3, Rad4) of the vehicle. Method according to one of Claims 9 to 10 characterized in that the method further comprises the steps of: determining that at least one of the vehicle wheels has erroneous tire pressure when at least one error quantity (err12, err13, err24) is outside a tolerance range for a target value or not equal to the target value, or determining in that all vehicle wheels have a set tire pressure when all error quantities (err12, err13, err24) are within the tolerance range for a setpoint or equal to the setpoint. Method according to one of Claims 9 to 11 characterized in that the method further comprises the steps of: determining that a vehicle wheel has faulty tire pressure when an error variable is out of tolerance for the setpoint or not equal to the setpoint, and the other two fault sizes are within the tolerance range for the setpoint or equal are the setpoint. Method according to at least one of Claims 9 to 12 characterized in that the method further comprises the step of: calculating the speed components (Vx, Vy) of the target wheel (Rad0) as a function of the angular speeds of the vehicle wheels, preferably taking into account only those vehicle wheels having a set tire pressure, and preferably outputting the calculated speed components (Vx, Vy) to a navigation system of the vehicle.

Images