Electronic wheel unit for a vehicle wheel

Abstract

An electronic wheel unit for detecting a tire pressure of a tire of a vehicle wheel, for storing tire information of the tire and for sending tire pressure information and tire information. The wheel unit is configured to allow the alteration of stored tire information in a first mode of operation and to prevent the alteration of stored tire information in a second mode of operation. To improve the integrity and safety of the stored tire information in this case, the wheel unit is further configured to change from the first mode of operation to the second mode of operation when a first mode change criterion is satisfied. The satisfaction of the first mode change criterion is dependent at least on an operating parameter of the vehicle wheel that is representative of a rotational movement of the vehicle wheel.

Claims

1. An electronic wheel unit for detecting a tire pressure of a tire of a vehicle wheel, for storing tire information of the tire and for sending tire pressure information and tire information, the electronic wheel unit comprising: a memory containing stored tire information; the wheel unit being configured to allow an alteration of the stored tire information in a first mode of operation and to prevent an alteration of the stored tire information in a second mode of operation; the wheel unit being further configured to change from the first mode of operation to the second mode of operation when a first mode change criterion is satisfied, wherein a satisfaction of the first mode change criterion is dependent at least on an operating parameter of the vehicle wheel that is representative of a rotational movement of the vehicle wheel; wherein the stored tire information, which is prevented from being altered in the second mode of operation and which is allowed to be altered in the first mode of operation, includes at least one item of data selected from the group consisting of a tire manufacturer, a tire type, a tire dimension, a bearing strength index and a speed index.

2. The electronic wheel unit according to claim 1, wherein the satisfaction of the first mode change criterion is dependent on a value of a rotational speed of the vehicle wheel.

3. The electronic wheel unit according to claim 2, wherein the satisfaction of the first mode change criterion at least requires the value of the rotational speed of the vehicle wheel to lie above a predetermined threshold value.

4. The electronic wheel unit according to claim 1, wherein the satisfaction of the first mode change criterion is further dependent on a content of the stored tire information.

5. The electronic wheel unit according to claim 4, wherein the satisfaction of the first mode change criterion requires that the tire information is not blank.

6. The electronic wheel unit according to claim 1, wherein the wheel unit is further configured to change from the second mode of operation to the first mode of operation when a second mode change criterion is satisfied, a satisfaction of the second mode change criterion being dependent at least on the operating parameter of the vehicle wheel that is representative of the rotational movement of the vehicle wheel.

7. The electronic wheel unit according to claim 6, wherein the satisfaction of the second mode change criterion is dependent at least on a value of the rotational speed of the vehicle wheel.

8. The electronic wheel unit according to claim 7, wherein the satisfaction of the second mode change criterion at least requires the value of the rotational speed of the vehicle wheel to lie below a predetermined threshold value.

9. The electronic wheel unit according to claim 8, wherein the satisfaction of the second mode change criterion further requires the tire pressure to lie below a predetermined threshold value.

10. The electronic wheel unit according to claim 1, wherein the wheel unit is further configured: to operate either in a first operating state, which prevents the alteration of the stored tire information, or in a second operating state, which permits the alteration of the stored tire information, in the first mode of operation; to change from the first operating state to the second operating state when a first state change criterion is satisfied; and to perform a change from the first mode of operation to the second mode of operation starting in the second operating state and to perform a change from the second mode of operation to the first mode of operation in the first operating state.

11. The electronic wheel unit according to claim 10, wherein a satisfaction of the first state change criterion is dependent at least on the operating parameter of the vehicle wheel that is representative of the rotational movement of the vehicle wheel and/or on the tire pressure.

12. The electronic wheel unit according to claim 10, wherein the wheel unit is further configured to change from the second operating state to the first operating state when a second state change criterion is satisfied.

13. The electronic wheel unit according to claim 12, wherein a satisfaction of the second state change criterion requires the tire pressure to lie below a predetermined threshold value.

14. An electronic wheel unit for detecting a tire pressure of a tire of a vehicle wheel, for storing tire information of the tire and for sending tire pressure information and tire information, the electronic wheel unit comprising: a memory containing stored tire information; the wheel unit being configured to allow an alteration of the stored tire information in a first mode of operation and to prevent an alteration of the stored tire information in a second mode of operation; the wheel unit being further configured to change from the first mode of operation to the second mode of operation when a first mode change criterion is satisfied, wherein a satisfaction of the first mode change criterion is dependent at least on an operating parameter of the vehicle wheel that is representative of a rotational movement of the vehicle wheel; wherein the satisfaction of the first mode change criterion is dependent on a value of a rotational speed of the vehicle wheel.

15. The electronic wheel unit according to claim 14, wherein the satisfaction of the first mode change criterion at least requires the value of the rotational speed of the vehicle wheel to lie above a predetermined threshold value.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention is described in more detail below on the basis of exemplary embodiments with reference to the enclosed drawings, in which:

(2) FIG. 1 shows a side view of a vehicle wheel equipped with an electronic wheel unit according to one exemplary embodiment,

(3) FIG. 2 shows a block diagram of the electronic wheel unit from FIG. 1, and

(4) FIG. 3 shows a diagram to illustrate different modes of operation and different operating states of the electronic wheel unit.

DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a tire 1 that, together with a rim 2, forms a vehicle wheel 3 of a motor vehicle (not depicted).

(6) The vehicle wheel 3 has an electronic wheel unit 10 arranged on it, specifically on an inner side of a tire bearing surface of the e.g. air-filled tire 1 (e.g. glued on or e.g. inserted in a pocket or e.g. detachably mounted on a glued-in support) in the depicted example.

(7) The main purpose of the wheel unit 10 is to measure the tire pressure in the tire 1 during operation of the relevant vehicle and, from time to time, to send applicable measurement results to a vehicle-based radio reception device (not depicted), i.e. one arranged in the relevant vehicle, by means of electromagnetic signals in the form of radio signals 22.

(8) The radio reception device decodes data included in the radio signal 22 and forwards said data to a central controller (not depicted) of the vehicle e.g. via a digital bus system (not depicted). The data included in the radio signal 22, in this case in particular measured values for the tire pressure, are evaluated by the central controller and/or made available for further use in other parts of on-board electronics of the vehicle.

(9) A further purpose of the electronic wheel unit 10 in the depicted exemplary embodiment is, from time to time, to transmit measurement results concerning a tire contact area, in this case e.g. a length L of a tire contact surface of the tire 1 when the tire 1 is rolling (cf. arrow in FIG. 1) on a driving surface, by means of the radio signals 22.

(10) Further, the radio signals 22 can be used to send data of tire information stored in the wheel unit 10 to the vehicle in part or in full. Tire-specific data of this kind can be used by the vehicle e.g. advantageously for controlling driving dynamics functions (ABS, ESP, etc.). Alternatively or additionally, there may be provision for the stored tire information to be used by the wheel unit 10 itself, for example in connection with the aforementioned detection of the tire contact area or other functionalities of the wheel unit 10 (e.g. tread depth ascertainment, wheel load ascertainment, etc.).

(11) In view of the typical case of multiple vehicle wheels on the same vehicle being equipped with electronic wheel units 10 of this kind, the data sent to the vehicle with the respective radio signal 22 finally also include an identification code identifying the sending wheel unit 10.

(12) The correct tire information, i.e. that matching the tire 1, can be stored in the wheel unit 10 provided for this tire 1 e.g. when the vehicle wheel 3 or the tire 1 is fitted to the relevant vehicle.

(13) FIG. 2 shows the design of the electronic wheel unit 10 in more detail.

(14) The wheel unit 10 contains a pressure sensor 12 for measuring the instantaneous tire pressure and an acceleration sensor 14 for measuring an instantaneous acceleration (in this case e.g. a radial acceleration). The pressure sensor 12 outputs a sensor signal sp representing the instantaneous tire pressure.

(15) A rotation of the vehicle wheel 3, symbolized by an arrow in FIG. 1, results in the acceleration sensor 14 measuring the radial acceleration present at the point at which the wheel unit 10 is arranged and outputting a corresponding sensor signal sa.

(16) Since this acceleration is made up of a component caused by the gravitation and a component caused by the rotation of the wheel 3, an appropriate evaluation of the sensor signal sa of the acceleration sensor 14 (e.g. by means of extraction of the gravitation component) allows the instantaneous rotational angular position and the instantaneous rotational angular velocity of the wheel 3 to be ascertained. Moreover, the tire contact surface formed in the lower circumferential region of the wheel 3 results in corresponding signal characteristics in the sensor signal delivered by the acceleration sensor 14 whenever the wheel unit 10 passes through the region of this tire contact surface.

(17) These signal characteristics, which arise periodically e.g. when traveling at constant speed, can therefore also be taken as a basis for ascertaining when the wheel unit 10 passes through the tire contact surface and, by virtue of a further evaluation of the sensor signal, in a simple manner the instantaneous rotational angular position (and therefore also the rotational angular velocity) of the wheel 3.

(18) Further, it would e.g. also be possible for what is known as a shock sensor or a deformation sensor or another suitable sensor to be used instead of the acceleration sensor 14 in order to realize detection of a rotational angular position and/or rotational angular velocity by means of evaluation of the sensor signal of said sensor.

(19) In the wheel unit 10, the measured values representative of the tire pressure and the acceleration, as can be seen in FIG. 2, are communicated to a program-controlled evaluation device, in this case a microcontroller 16, which takes them as a basis for producing data D and forwards said data to a radio transmission device 20, by means of which a respective radio signal 22 including these data D is sent.

(20) The microcontroller 16 is connected to a memory device 18 associated with the microcontroller 16, which memory device, in the exemplary embodiment depicted, stores a program controlling the operation of the microcontroller 16 and the aforementioned tire information.

(21) The storage of the tire information or a subsequent update of the tire information in the memory device 18 can be realized e.g. by virtue of the depicted radio transmission device 20 also having a functionality for receiving applicable radio signals, in order to wirelessly transmit tire information to the memory device 18 via this radio transmission device 20 and the microcontroller 16. Alternatively, the wheel unit 10 may be equipped e.g. with a radio reception device provided specifically for that purpose.

(22) The innovation according to the present invention relates in the depicted exemplary embodiment to the manner of operation of the wheel unit 10 or the microcontroller 16 thereof in connection with the alteration of the tire information stored in the memory device 18, as explained in more detail below.

(23) In this regard, FIG. 3 illustrates operating states S0, S1 and S2 of the wheel unit 10 that are provided in the depicted exemplary embodiment. On the basis of the program control of the microcontroller 16, these operating states are implemented, in the depicted exemplary embodiment, by the software (control program) stored in the memory device 18.

(24) In addition, the possible changes between the operating states S0, S1 and S2 in the depicted example are symbolized by applicable arrows t01, t10, t12 and t20 in FIG. 3.

(25) The operating states S0 and S1 together form a first mode of operation M1, whereas the operating state S2 is synonymous with a second mode of operation M2 in the depicted example.

(26) The operating state S0 is an invalid data state, in which the tire information stored in the wheel unit 10 is invalid or blank. The invalidity of the tire information may be implemented in software e.g. by setting an appropriate flag.

(27) The operating state S0 obtains, by way of example, when the wheel unit 10 is provided in a garage for integration into the vehicle wheel 3 or the tire 1. The wheel unit 10 is designed to prevent alteration of stored tire information in the operating state S0.

(28) Alteration of stored tire information, e.g. transmission of (updated) tire information to the wheel unit 10, is enabled in the operating state S1, on the other hand. Such a data transmission is symbolized by the arrow dw in FIG. 3. In the operating state S1, it is possible e.g. for tire information to be stored or for already stored tire information to be updated.

(29) The change t01 from the first operating state S0 to the second operating state S1 is made as soon as the wheel unit 10 identifies that a first state change criterion is satisfied. The first state change criterion is satisfied in the depicted example when the detected tire pressure is above a predetermined threshold value (in this case e.g. 1.5 bars) and the detected rotation speed of the vehicle wheel 3 or tire 1 is below a predetermined threshold value (in this case e.g. 4 rpm) and a change command transmitted by radio technology is received. The change command is sent e.g. by garage personnel (by means of suitable technical equipment) in this case. Separately from this change command or within the same radio signal, it is then possible for the radio transmission dw of data for altering the stored tire information to be effected.

(30) The operating state S1 is therefore a write state, in which alteration of stored tire information is enabled.

(31) Optionally, there may be provision in the operating state S1 for validation of the stored tire information, which can be brought about e.g. by the garage personnel, also to be enabled (e.g. again in a manner using radio technology).

(32) The change from the operating state S1 back to the operating state S0 is made when a second state change criterion is satisfied, which, in the depicted example, is satisfied when the tire pressure is below a predetermined threshold value. In this case, the tire information can be altered further (or if need be a validation can be effected) only when satisfaction of the first state change criterion results in a change from the operating state S0 to the operating state S1 being made again.

(33) From the operating state S1, the change t12 to the operating state S2 is made, synonymous with a change from the first mode of operation M1 to the second mode of operation M2, when a first mode change criterion is satisfied, this criterion being satisfied in the depicted example if the stored tire information is not blank and the detected rotation speed of the vehicle wheel 3 or tire 1 is above a predetermined threshold value.

(34) In the depicted example, the threshold value for the rotation speed is chosen such that it identifies when a driving mode of the relevant vehicle begins, and thus the change to the operating state S2 is triggered if the tire information is not blank.

(35) The operating state S2 is a Valid data/blocked data state in which the stored tire information is regarded as valid and alteration of the stored tire information is prevented. In the normal driving mode of the vehicle, it is therefore impossible for the stored tire information to be manipulated e.g. inadvertently or in a criminal manner.

(36) The change t20 from the operating state S2 or the second mode of operation M2 to the operating state S0 or the first mode of operation M1 is made when a second mode change criterion is satisfied, this being satisfied in the depicted example if the tire pressure is below a predetermined threshold value and the rotation speed of the vehicle wheel 3 or of the tire 1 is below a predetermined threshold value.

(37) In the depicted example, this second mode change criterion detects e.g. the case in which the tire 1 bursts or drastically loses tire pressure in another manner and the vehicle is brought to a standstill.

(38) Optionally, the change t20 may have provision for the stored tire information to be erased and therefore blank tire information to result.

LIST OF REFERENCE SIGNS

(39) 1 tire

(40) 2 rim

(41) 3 vehicle wheel

(42) L tire contact area length

(43) 10 electronic wheel unit

(44) 12 pressure sensor

(45) sp sensor signal of the pressure sensor

(46) 14 acceleration sensor

(47) sa sensor signal of the acceleration sensor

(48) 16 microcontroller

(49) 18 memory device

(50) D data

(51) 20 radio transmission device

(52) 22 radio signal

(53) M1 first mode of operation

(54) M2 second mode of operation

(55) S0 first operating state of the first mode of operation

(56) S1 second operating state of the first mode of operation

(57) S2 operating state of the second mode of operation

(58) dw transmission of data (alteration of tire information)