Electronic wheel unit for installation on a vehicle wheel

Abstract

Electronic wheel unit (10) for arrangement on a vehicle wheel (1) of a vehicle, comprising - at least one sensor (30) for detecting at least one wheel operating parameter, - a control device (40) which is designed to generate wheel operating data based on the at least one wheel operating parameter, - a radio device (50) for transmitting radio data signals (F) containing the wheel operating data, - a power supply device (22, 24) for electrically supplying the wheel unit (10), wherein the power supply device (22, 24) comprises an energy harvesting device (22) for converting mechanical energy obtained during rotation of the vehicle wheel (1) into electrical energy and an electrical battery (24), and wherein the wheel unit (10) is designed to provide the electrical supply by means of the energy harvesting device (22) in the event of sufficient electrical energy being generated by the energy harvesting device (22) and to provide the electrical supply by means of the electrical battery (24) in the event of insufficient electrical energy being generated by the energy harvesting device (22), and wherein the electronic wheel unit (10) further comprises: - a switching device (26, 28) for switching between the energy harvesting device (22) and the electric battery (24) for the electrical supply of the wheel unit (10), comprising a controllable switch (26) and a control device (28) for controlling the switch (26), characterized in that the at least one wheel operating parameter comprises an acceleration parameter and the control device (28) effects the switching as a function of the acceleration parameter or a parameter derived therefrom.

Description

[0001] The present invention relates to an electronic wheel unit according to the preamble of claim 1.

[0002] Such wheel units for arrangement on a vehicle wheel of a vehicle are known in a variety of designs and have at least one sensor (e.g. acceleration sensor, pressure sensor, temperature sensor, etc.) for detecting at least one wheel operating parameter (e.g. acceleration, tire pressure, tire temperature, etc.), a control device provided for generating wheel operating data based on the at least one wheel operating parameter, a radio device for transmitting radio data signals containing the wheel operating data, and a power supply device (e.g. electric battery) for electrically supplying the wheel unit.

[0003] The disadvantage of wheel units that are usually powered by an electric battery is the limited lifespan of the battery and thus the need for regular replacement of this battery or the entire wheel unit.

[0004] Such wheel units are disclosed, for example, in US 2012 / 0169142 A1 and DE 10 2007 010 505 A1. In each case, an energy converter is used to supply energy to actuate or switch on a switch when the relevant vehicle wheel rotates. This switch supplies the wheel unit with energy from the electric battery and thus switches it on. As soon as the vehicle wheel stops rotating, the switch is switched off due to a lack of voltage supply, and thus the wheel unit.

[0005] As an alternative to the electrical supply of the wheel unit by means of a battery, it has already been proposed to provide the electrical supply by means of an “energy harvesting device” with which mechanical energy is extracted when the vehicle wheel rotates and converted into electrical energy (“energy harvesting”).

[0006] The disadvantage of such wheel units, however, is that the energy supply is not guaranteed continuously (but only when there is a sufficiently large energy harvest) and thus the functionality of the wheel unit is not ensured continuously.

[0007] Against this background, it has already been proposed to provide the electrical supply to a wheel unit by means of an electrical energy storage device (rechargeable electric battery) fed by an energy harvesting device.

[0008] For example, US 2011 / 0001493 A1 describes an electronic wheel unit powered by a rechargeable electric battery, with a corresponding energy harvesting device used to (re)charge the rechargeable electric battery. However, the disadvantage of such wheel units is the high cost of both the relatively powerful energy harvesting device required for this purpose and the electrical energy storage device.

[0009] Furthermore, US 2002 / 0088517 A1 describes an electronic wheel unit which is powered by a rechargeable battery, wherein the battery is recharged wirelessly (inductively) by means of a charging and query device when required.

[0010] Further electronic wheel units comprising an energy harvesting device are known, for example, from US 2012 / 0261991 A1 and US 2017 / 0040911 A1.

[0011] From the generic US 2007 / 0180894 A1, an electronic wheel unit for arrangement on a vehicle wheel of a vehicle is known, comprising a sensor for detecting a wheel operating parameter, a control device for generating wheel operating data based on the wheel operating parameter, a radio device for transmitting radio data signals containing the wheel operating data, and a power supply device with an energy harvesting device designed as a generator and an electric battery for electrically supplying the wheel unit. A switching device switches the electrical supply of the wheel unit from the electric battery to the energy harvesting device if and as long as the voltage of the energy harvesting device is greater than the voltage of the battery.

[0012] It is an object of the present invention to enable both a long operational readiness and a continuous electrical supply in an electronic wheel unit of the type mentioned at the outset in a cost-effective manner.

[0013] According to the present invention, this object is achieved by an electronic wheel unit according to claim 1. The dependent claims relate to advantageous developments of the invention.

[0014] It is provided that the power supply device has an energy harvesting device for converting mechanical energy obtained during rotation of the vehicle wheel into electrical energy and an electrical battery, and that the wheel unit is designed to provide the electrical supply by means of the energy harvesting device in the event of sufficient electrical energy being generated by the energy harvesting device and to provide the electrical supply by means of the electrical battery in the event of insufficient electrical energy being generated by the energy harvesting device.

[0015] If the electronic wheel unit according to the invention is equipped, for example, with a non-rechargeable electric battery dimensioned as in conventional wheel units, the operational readiness time is considerably extended. Alternatively, in this case, however, increased power (e.g. radio transmission power, frequency of detections and / or frequency of radio data signal transmissions) can also be provided compared to conventional systems. Although the “electric battery” in the invention is preferably a non-rechargeable battery, the use of a rechargeable battery should not be excluded at this point. Furthermore, according to a further development of the invention, electrical energy generated by the energy harvesting device is temporarily stored by means of a rechargeable battery (accumulator) arranged at an output of the energy harvesting device and thus, for example,an electrical direct voltage output by the energy harvesting device, e.g. after voltage rectification, is buffered.

[0016] It is further provided that the wheel unit further comprises a switching device for switching between the energy harvesting device and the electric battery for the electrical supply of the wheel unit.

[0017] This enables “intelligent” (demand-based) switching between the two power supplies (energy harvesting and electric battery).

[0018] Advantageously, the relevant prior art can be used for the specific design of the energy harvesting device used in the invention. In particular, the energy harvesting device can comprise, for example, a mass that is movable (by the action of acceleration forces) (and optionally, for example, spring-loaded, deflectable from a zero position) and a converter device arranged stationary relative to the mass (relative to the wheel unit) for converting this movement into electrical energy or an electrical voltage. The converter device can comprise, for example, a piezoelectric material acted upon by the mass. When using a permanent magnet as the movable mass, the converter device can comprise, for example, an induction coil. A rectifier circuit (e.g., a bridge rectifier) ​​can be provided at the output of the converter device to provide the DC voltage required to supply the wheel unit with power.

[0019] In the wheel unit according to the invention, the aforementioned acceleration forces arise with each rotation of the respective vehicle wheel. In practice, the faster the wheel rotates or the vehicle travels, the more electrical energy can be generated by the energy harvesting device. It should be noted that energy harvesting devices of the type of interest here are often designed to primarily utilize the oscillations or vibrations of the wheel unit that typically occur at higher vehicle speeds (and less the variation in the gravitational force dependent on the wheel rotation angle) to generate electrical energy.

[0020] In an advantageous further development, an electrical accumulator for temporarily storing the generated electrical energy or thus buffering the direct voltage generated by the energy harvesting device is provided at an output of the energy harvesting device, following a rectifier circuit.

[0021] It is further provided that the aforementioned switching device has a controllable switch and a control device for controlling the switch.

[0022] The switch can be designed, for example, as a semiconductor switch (e.g., a transistor) or comprise such a semiconductor switch. The switch can be single-pole or, for example, double-pole (e.g., formed from two semiconductor switches).

[0023] According to the invention, it is provided that the at least one wheel operating parameter (detected by the sensor(s)) comprises an acceleration parameter and the control device effects the switching as a function of the acceleration parameter or a parameter derived therefrom.

[0024] For example, the acceleration parameter can be a radial acceleration (acting at the wheel unit's mounting location). Alternatively, the acceleration parameter can represent a tangential acceleration (or another acceleration). Furthermore, the acceleration parameter can also be the intensity of a "vibration" at the wheel unit's mounting location or the intensity of a "shock" (short-term, strong variations in acceleration) at the wheel unit's mounting location, such as typically occur during wheel rotation with each passage of the wheel unit through the tire contact patch area and can be measured with a vibration or shock sensor.

[0025] A parameter derived from such an acceleration parameter can be a parameter determined by a mathematical calculation or an algorithm using the detected acceleration parameter (including, for example, its temporal progression), such as an acceleration intensity measure, such as an average of an absolute value of a specific acceleration (e.g., radial or tangential acceleration) within a predetermined time interval (e.g., a moving average). In particular, a parameter representative of a wheel rotational speed (and thus also, for example, the speed of the vehicle in question) can be provided as a derived parameter, e.g., a parameter proportional to the wheel rotational speed.

[0026] The aforementioned switching depending on the acceleration parameter or a parameter derived therefrom has the advantage, on the one hand, that such an acceleration parameter, with regard to the energy harvested according to the invention (from mechanical energy during rotation of the vehicle wheel in question), generally also represents a measure of the extent of the electrical energy available through the energy harvest, and, on the other hand, the advantage that in many electronic wheel units of the type of interest here, such an acceleration parameter or a parameter derived therefrom is determined by the control device anyway (in particular, for example, for determining the wheel rotational speed), so that it can also be used to implement the invention without additional effort.

[0027] The parameter in question used to control the switching processes can, in particular, be used as a time-averaged parameter (e.g., moving average), wherein a time interval over which the average is calculated can, for example, be at least 1 s.

[0028] The switching depending on the acceleration parameter or a parameter derived therefrom can be designed, for example, such that when the relevant parameter exceeds a predetermined first threshold value, the electrical supply of the wheel unit is switched to the energy harvesting device, and when this parameter falls below a predetermined second threshold value, the electrical supply of the wheel unit is switched to the electric battery. The two threshold values ​​can, for example, be specified as the same or different. Preferably, at least one of the two threshold values ​​(in particular both threshold values) is at least 1.1 times, in particular at least 1.2 times, the value of the parameter above which sufficient generation of electrical energy by the energy harvesting device is to be expected.On the other hand, each of the two threshold values ​​(in particular both threshold values) can, for example, be a maximum of 1.5 times, in particular a maximum of 1.4 times, this parameter value.

[0029] In a preferred embodiment, it is provided that the control device is further designed to implement the actuation device. The control device can, for example, have a program-controlled computer device (e.g., a microcontroller or the like), by means of which, for example, not only the wheel operating data to be transmitted is generated (calculated), but advantageously also a actuation signal for the switch can be generated. In a first implementation variant of this embodiment, the control device generates the actuation signal. In a second implementation variant, the actuation device is designed separately from the control device, but receives information and / or commands from the control device, which are taken into account by the actuation device when generating the actuation signal.

[0030] Alternatively to this embodiment, the control device and the actuation device could also be implemented by functionally separate devices.

[0031] In one embodiment, it is provided that the wheel unit further comprises a voltage measuring device for measuring an electrical voltage generated by the energy harvesting device, wherein the control device effects the switching as a function of this voltage.

[0032] In the case of alternating voltage generation by the energy harvesting device, this voltage can be used, in particular, for example, as an average absolute value ("effective alternating voltage") of the alternating voltage, whereby averaging can optionally be provided over a relatively long time interval (compared to the sign change frequency or frequency of the generated alternating voltage). Alternatively, this voltage can also be used, for example, as an average value of a rectified version of a voltage originally generated as alternating voltage by the energy harvesting device. In both cases, the time interval over which the averaging is carried out can be, for example, at least 1 s.

[0033] In a further development, an electrical energy storage device, e.g., an electrical accumulator, is provided at an output of the energy harvesting device for temporarily storing the electrical energy generated by the energy harvesting device. This allows, for example, an output voltage of the energy harvesting device that is ultimately provided (after rectification) as a direct voltage to be buffered, which advantageously enables a somewhat "slower" and thus easier to implement switching strategy. The energy storage device can, in particular, be dimensioned such that the energy stored therein after full charging covers the energy requirement (or a maximum energy requirement) of the wheel unit for at least 1 s, in particular at least 5 s. On the other hand, it is usually sufficient if this energy covers the energy requirement (or maximum energy requirement) of the wheel unit for a maximum of 30 s, in particular a maximum of 15 s.

[0034] The switching depending on the measured voltage can, for example, be designed such that when the generated voltage exceeds a predetermined first threshold, the electrical supply of the wheel unit is switched to the energy harvesting device, and when the generated voltage falls below a predetermined second threshold, the electrical supply of the wheel unit is switched to the electric battery. The two threshold values ​​can, for example, be specified to be the same or different. Preferably, at least one of the two threshold values ​​(in particular both threshold values) is at least 0.9 times, in particular at least 1 times, the nominal voltage of the electric battery. On the other hand, each of the two threshold values ​​(in particular both threshold values) can, for example, be a maximum of 1.4 times, in particular a maximum of 1.2 times, this nominal voltage.

[0035] Returning once again to the aforementioned first and second threshold values ​​(which may optionally be selected to be of equal size), exceeding or falling below which causes the corresponding switching process, according to a further development it is provided that at least one of the threshold values ​​(preferably both) is not fixedly predetermined, but is predetermined depending on an operating state of the electronic wheel unit.

[0036] This further development can be provided for both the explained parameter threshold values ​​and the explained voltage threshold values.

[0037] The further development takes into account the fact that the electronic wheel unit can have several different operating modes which differ from one another in their electrical energy consumption, so that in this case, for example, the first threshold value (when exceeded, the energy harvesting device is switched over) and / or the second threshold value (when fallen below, the electric battery is switched over) can be specified higher in temporal phases of an operating mode with a relatively high energy requirement than in temporal phases of an operating mode with a relatively low energy requirement.

[0038] As an operating mode with a relatively high energy requirement, in particular, an operating mode can be provided in which a detection of the at least one wheel operating parameter and / or a transmission of the radio data signal takes place relatively frequently (ie at shorter time intervals).

[0039] The radio device used in the invention can transmit the radio data signal, for example, according to a common radio standard such as Bluetooth or the like.

[0040] The frequencies of the detections and / or transmissions can, for example, be determined or controlled by the control device according to an operating strategy of the electronic wheel unit (e.g. implemented by control software running on it).

[0041] An operating mode with relatively low energy requirements can, in particular, be provided, for example, as an operating mode in which the radio data signal is detected and / or transmitted relatively rarely (i.e., at longer time intervals). This can, in particular, be a so-called sleep mode (e.g., when the vehicle is parked), in which no detections to generate wheel operating data and no radio transmissions take place, but rather only detections to detect the onset of vehicle travel take place (and, for example, at longer time intervals), in order to switch the electronic wheel unit to a normal operating mode with regular detections to generate wheel operating data (i.e., to "wake it up") in the event of such a detection.

[0042] In one embodiment of the invention, the wheel unit is further designed to forcibly supply electricity by means of the electric battery for a specific time interval when the vehicle starts to travel (beginning of a driving cycle).

[0043] This advantageously takes into account the fact that at the beginning of a driving cycle, sufficient energy cannot usually be provided from the energy harvesting device. In these cases, the electronic wheel unit (or its control unit) can temporarily (i.e., for the specified time interval) override the application of the relevant "switchover criterion" and initially specify the electrical supply from the electric battery.

[0044] The specific time interval can be defined, for example, by a fixed period of time (e.g., at least 30 s, in particular, e.g., at least 60 s). Alternatively (or additionally), the time interval can also be defined, for example, by a (e.g., fixed) predetermined number (e.g., more than 10, in particular, e.g., more than 20) of radio data signals (e.g., "data telegrams") transmitted after the start of the journey.

[0045] Until the start of a journey, the electronic wheel unit can, for example, be in a so-called rest mode (parking mode), whereby immediately after the start of the journey a mode change to another operating mode, e.g. a "learning mode", takes place, in which, for example, a so-called localization of the electronic wheel units takes place, i.e. the respective installation positions of the individual wheel units on the vehicle are determined by a vehicle-side device (cf., for example, DE 10 2009 059 788 A1 or DE 10 2015 212 945 A1). Only after the time interval has elapsed (e.g. sending a certain number of telegrams, e.g. 40) is the relevant switching criterion (e.g. acceleration parameters, vehicle speed, etc.) then used. This advantageously ensures particularly reliable learning (localization process).

[0046] In one embodiment, the electronic wheel unit is provided, for example, as a wheel-side component of a tire pressure monitoring system (TPMS for short) for arrangement in an air-filled tire of the vehicle wheel. The at least one sensor of the wheel unit comprises a tire pressure sensor for transmitting wheel operating data, including information about the tire pressure, to a vehicle-mounted radio receiver based on the detected tire pressure using the radio data signals. Alternatively or additionally, further information can be transmitted to the vehicle, such as a tire temperature and / or a wheel rotational position and / or wheel rotational position.

[0047] The invention will be further described below using exemplary embodiments with reference to the accompanying drawings, each of which shows: Fig. 1 a schematic side view of a vehicle wheel with an electronic wheel unit arranged therein according to an embodiment, Fig. 2 an exemplary time course diagram to illustrate switching processes in an electronic wheel unit, Fig. 3 a block diagram of an electronic wheel unit according to an embodiment, and Fig. 4 a block diagram of an electronic wheel unit according to another embodiment.

[0048] Fig. Figure 1 shows a vehicle wheel 1 of a (not shown) vehicle, such as a passenger car, on which an electronic wheel unit 10 is arranged to acquire wheel operating data during a journey of the vehicle and to transmit it by radio to a receiver device arranged on the vehicle. Fig. 1, a wheel rotation 2 is symbolized by an arrow and a radio data signal F sent by the wheel unit 10 is shown.

[0049] In the example shown, the electronic wheel unit 10 is arranged on an inner side of a tread of an air-filled tire of the vehicle wheel 1, e.g., glued or locked in a glued-in holder.

[0050] Fig. 3 shows a block diagram of an example of Fig. 1 usable electronic wheel unit 10 according to an embodiment.

[0051] The wheel unit 10 has at least one sensor 30 for detecting at least one wheel operating parameter (e.g. acceleration, tire pressure, tire temperature, etc.), wherein preferably several corresponding sensors (e.g. acceleration sensor, pressure sensor, temperature sensor, etc.) are provided, but in Fig. 3 For the sake of simplicity, only one sensor is shown.

[0052] The wheel unit 10 further comprises a control device 40 configured to generate corresponding wheel operating data based on the at least one detected wheel operating parameter. Within the scope of the invention, the control device 40 is preferably configured as a program-controlled electronic control device (e.g., a microcontroller) on which a control program for controlling the operation of the control device 40 runs.

[0053] In the example shown, the wheel operating data are calculated by means of such a control program based on the at least one wheel operating parameter, for which purpose the sensor 30 or each of the existing sensors outputs a sensor signal representative of a respective wheel operating parameter to the control device 40.

[0054] The wheel operating data generated by the control device 40 may include information about the wheel operating parameter(s) and / or other information derived therefrom relating to the wheel operation.

[0055] A suitable evaluation of a sensor signal representative of a wheel operating parameter “acceleration” (e.g. radial acceleration) allows, for example, the determination of a rotational speed and / or rotational position of the vehicle wheel 1 and thus the inclusion of corresponding information in the wheel operating data.

[0056] The wheel unit 10 further comprises a radio device 50 for transmitting the radio data signals F containing the wheel operating data to a radio device (not shown) of the relevant vehicle.

[0057] Preferably, the radio device 50 of the wheel unit 10 is designed for bidirectional data communication, i.e., both for transmitting the radio data signals F to the radio device of the vehicle and for receiving radio data signals transmitted by the radio device arranged on the vehicle (e.g., according to the Bluetooth standard). The latter radio data signals can, for example, be used to initiate a readout of data from the electronic wheel unit 10, e.g., by workshop personnel or, for example, by a central control unit of the vehicle. Alternatively, such received radio data signals can also be used, for example, to modify the operation of the control device 40. They can also be used, for example, to transmit vehicle operating parameters (e.g., vehicle speed, etc.) or other information (e.g., tire information data) to the electronic wheel unit 10 for consideration during the operation of the control device 40.

[0058] The wheel unit 10 further comprises a power supply device 22, 24 for electrically supplying the wheel unit 10, which has both an energy harvesting device 22 for converting mechanical energy obtained during rotation of the vehicle wheel 1 into electrical energy (“energy harvesting”) and a non-rechargeable electric battery 24 (e.g. lithium battery).

[0059] The wheel unit 10 is designed to provide the electrical supply by means of the energy harvesting device 22 in the event of sufficient generation of electrical energy by the energy harvesting device 22 and to provide the electrical supply by means of the electric battery 24 in the event of insufficient generation of electrical energy by the energy harvesting device 22.

[0060] This advantageously enables both a long operational readiness of the electronic wheel unit 10 and a continuous electrical supply.

[0061] In the illustrated embodiment, the wheel unit 10 has a switching device 26, 28 for switching between the energy harvesting device 22 and the electric battery 24 as an energy source for the electrical supply of the wheel unit 10.

[0062] In the example, the switching device 26, 28 is formed by a controllable switch 26 and a control device 28 that outputs a control signal SS for controlling the switch 26. The switch 26 can be single-pole or, for example, double-pole, for example, consisting of a corresponding number of transistors controlled by the control signal SS.

[0063] In the illustrated embodiment, the control device 28 is implemented as a functional component of the control device 40, ie the control device 40 is also used here to generate the control signal SS.

[0064] In this case, the control device 40 requires information as to whether the generation of electrical energy by the energy harvesting device 22 is sufficient or insufficient to supply electrical power to the wheel unit 10.

[0065] There are various ways to obtain this information. One possibility is that at least one detected wheel operating parameter and / or a parameter derived from at least one detected wheel operating parameter is used by the control device 40 (or the control program running thereon) for this purpose, and switching between the two power supplies is effected depending on the at least one acceleration parameter or the parameter derived therefrom.

[0066] In a more specific embodiment, the at least one wheel operating parameter comprises an acceleration parameter (e.g. radial acceleration, tangential acceleration, or otherwise oriented acceleration at the mounting location of the electronic wheel unit 10) and the control device 40 or its functional component 28 causes the switching depending on this acceleration parameter or a parameter derived therefrom (e.g. rotational speed of the vehicle wheel 1).

[0067] If, as in the illustrated embodiment, the radio device 50 is designed for bidirectional radio data communication with the vehicle (e.g., central control unit in the vehicle), then, as an alternative or in addition to using a wheel operating parameter detected by the electronic wheel unit 10 itself (and / or a parameter derived therefrom), information transmitted via a radio data signal from the vehicle to the electronic wheel unit 10 can also be used. An example of this would be the transmission of information about the vehicle speed from the vehicle to the electronic wheel unit 10, so that the electronic wheel unit 10 causes the switch 26 to switch depending on the vehicle speed thus determined.

[0068] For example, at relatively low vehicle speeds of, for example, less than a certain threshold value, for example, 30 km / h, or, for example, 20 km / h, the control signal SS could be used to switch to an electrical energy supply via the electric battery 24, whereas if such a predetermined threshold value (speed threshold value) is exceeded, the electrical energy supply is switched to the energy harvesting device 22.

[0069] In one embodiment of the invention, the actuation device 28 or, in this example, the control device 40 is designed to effect the electrical supply of the wheel unit 10 by means of the electric battery for a specific time interval at the beginning of each driving cycle of the vehicle in question (e.g. detectable by the start of a wheel rotation) (regardless of the switching criterion used subsequently, here, for example, vehicle speed).

[0070] In the following description of further exemplary embodiments, the same reference numerals are used for components with equivalent functions. In doing so, only the differences from the previously described exemplary embodiment(s) are discussed, and otherwise, explicit reference is hereby made to the description of previous exemplary embodiments.

[0071] Fig. Figure 4 shows a further embodiment of an electronic wheel unit 10, which has the same components as already described with reference to Fig. 3. In contrast to the example of Fig. 3 is for the wheel unit 10 of Fig. 4, however, the control device 28 is not implemented by the control device 40, but by a functionally separate device. Independently of this, there is another difference between the wheel unit 10 and Fig. 4 in that the control device 28 does not form the control signal SS as a function of a wheel operating parameter detected by the sensor 30 (and / or further sensors) or a parameter otherwise obtained by the control device 40, but that the control device 28 has a voltage measuring device for measuring the electrical voltage generated by the energy harvesting device 22, wherein the control device 28 effects the switching as a function of this voltage.

[0072] The switching depending on the measured voltage can be configured, for example, such that when the generated voltage exceeds a predetermined first threshold, the electrical supply of the wheel unit 10 is switched to the energy harvesting device 22, and when the generated voltage falls below a predetermined second threshold, the electrical supply of the wheel unit 10 is switched to the electric battery 24. The two thresholds can, for example, be equal.

[0073] Deviating from the example according to Fig. 4, a voltage measuring device used in this way could also be provided as a (peripheral) component of the control device 40. A further modification of the example of Fig. 4 would be, for example, a control device 28 provided separately from the control device 40, as shown, which, however, does not generate the control signal SS used for switching based on a voltage measurement, but rather based on (or taking into account) information transmitted from the control device 40 to the control device 28 (e.g., about the wheel rotational speed or the vehicle speed) and / or taking into account commands issued by the control device 40 to the control device 28. For example, the control device 40 could thus forcibly supply electricity using the electric battery for a specific time interval at the beginning of a driving cycle.

[0074] The electronic wheel units 10 of the with reference to the Fig. 3 and Fig. 4 can be provided in particular for arrangement in an air-filled tire of the relevant vehicle wheel, wherein the at least one sensor 30 comprises a tire pressure sensor. In this case, the wheel unit 10 can represent the wheel-side component of a tire pressure monitoring system (TPMS) of the vehicle.

[0075] The aforementioned threshold values, which, when exceeded or undershot, trigger a switching process, be they, for example, threshold values ​​for an acceleration parameter, for the wheel rotation speed, for the vehicle speed ( Fig. 3) or, for example, for an electrical voltage measured at the energy harvesting device 22 ( Fig. 4), can be specified according to a further development depending on an operating state of the electronic wheel unit 10.

[0076] Fig. 2 uses an exemplary timing diagram to illustrate switching processes in an electronic wheel unit 10 of the type described here.

[0077] Fig. 2 shows in partial diagrams from top to bottom, each as a function of time t, the curves of an electrical power P ( Fig. 2 above), an electrical power P22 generated by the energy harvesting device 22 ( Fig. 2 middle) and a control signal SS generated based on it ( Fig. 2 below).

[0078] In the example shown, it is assumed that when the vehicle is parked, the wheel unit 10 is initially (time t = 0) in a “rest mode” and is supplied from the electric battery 24.

[0079] At time t = 1 min, the vehicle starts to move, which is detected by the wheel unit 10 (e.g., based on a detected acceleration parameter and / or a wake-up signal received from the vehicle), whereupon the wheel unit 10 switches to a “normal operating mode” with a considerably increased electrical power requirement (approximately at t = 1.1 min).

[0080] In normal operating mode, the electrical power requirement P of the wheel unit 10, in the example, fluctuates between a first value P1 and a second value P2 that is increased relative to the first value. The power P1 is required for the operation of the at least one sensor 30 for detecting the wheel operating parameter(s) and / or calculations based thereon for generating the wheel operating data and / or other evaluations by the control device 40, whereas from time to time an additional energy requirement arises due to the transmission of the radio data signals F that then takes place, which temporarily leads to the increased power requirement P2.

[0081] The energy generated by the energy harvesting device 22, in Fig. 2 The power P22 shown as an example depends in practice, for example, very strongly on the current vehicle speed, whereby the relevant sub-diagram ( Fig. 2 middle) shows that the generated power P22 is sufficient to cover the power demand P in some time intervals and insufficient (i.e., not sufficient) in other time intervals. For the time intervals of insufficient generation of electrical energy by the energy harvesting device 22, the (logical) control signal SS changes from a value of "1" (for energy supply from the electric battery 24) to a value of "0" (for energy supply from the energy harvesting device 22).

[0082] Advantageously, the realization of the invention does not require precise knowledge of the Fig.2 during operation of the wheel unit 10. Rather, a threshold value of a suitably selected parameter (e.g., acceleration parameter or parameters derived therefrom, vehicle speed, electrical voltage, etc.) can be determined empirically in advance for the electronic wheel unit 10 and the energy harvesting device 22 used therein. If exceeded or undershot, it can be expected that the energy supply to the wheel unit 10 by the energy harvesting device 22 is sufficient or insufficient, respectively.

Claims

[1] Electronic wheel unit (10) for arrangement on a vehicle wheel (1) of a vehicle, comprising - at least one sensor (30) for recording at least one wheel operating parameter, - a control device (40) designed to generate wheel operating data based on at least one wheel operating parameter, - a radio device (50) for transmitting radio data signals (F) including the wheel operating data, - a power supply device (22, 24) for the electrical supply of the wheel unit (10), wherein the power supply device (22, 24) comprises an energy harvesting device (22) for converting mechanical energy obtained during rotation of the vehicle wheel (1) into electrical energy and an electric battery (24), and wherein the wheel unit (10) is configured to provide the electrical supply by means of the energy harvesting device (22) in the event of sufficient generation of electrical energy by the energy harvesting device (22) and to provide the electrical supply by means of the electric battery (24) in the event of insufficient generation of electrical energy by the energy harvesting device (22), and wherein the electronic wheel unit (10) further comprises: - a switching device (26, 28) for switching between the energy harvesting device (22) and the electric battery (24) for the electrical supply of the wheel unit (10), comprising a controllable switch (26) and a control device (28) for controlling the switch (26), characterized by , that at least one wheel operating parameter includes an acceleration parameter and the control device (28) causes the switching depending on the acceleration parameter or a parameter derived therefrom. [2] Electronic wheel unit (10) according to claim 1, wherein the control unit (40) is further configured to implement the control unit (28). [3] Electronic wheel unit (10) according to one of the preceding claims, wherein the wheel unit (10) is further configured to provide the electrical supply by means of the electric battery (24) for a certain time interval in the event of the commencement of a journey of the vehicle. [4] Electronic wheel unit (10) according to one of the preceding claims, wherein the control device (28) is configured to use the parameter used for controlling the switching operations as a time-averaged parameter. [5] Electronic wheel unit (10) according to one of the preceding claims, wherein an electrical energy storage device, in particular an electrical accumulator, is provided at an output of the energy harvesting device (22) for intermediate storage of the electrical energy generated by the energy harvesting device (22). [6] Electronic wheel unit (10) according to one of the preceding claims for arrangement in an air-filled tire of the vehicle wheel (1), wherein the at least one sensor (30) comprises a tire pressure sensor and an acceleration sensor.

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