Tire monitoring system for a motor vehicle, as well as motor vehicle with a related tire monitoring system

Description

[0001] The invention relates to a tire monitoring system for a motor vehicle, in particular a commercial vehicle, in particular a tire pressure monitoring system for monitoring the tire pressure of a truck, and to a motor vehicle, in particular a commercial vehicle, with a corresponding tire monitoring system.

[0002] Tire pressure monitoring systems (TPMS) monitor tire pressure in motor vehicles to prevent accidents caused by incorrect tire pressure. Furthermore, optimal tire pressure saves fuel and avoids unnecessary tire wear.

[0003] For trucks, direct measurement systems are typically used, in which wheel electronics actively monitor the internal pressure and, for example, the air temperature inside a tire. This information, along with an identifier, is transmitted wirelessly at regular intervals to a receiver in the truck and evaluated in a control unit. Systems of this type can detect pressure loss in all tires because they directly monitor the pressure of each tire.

[0004] A tire pressure monitoring system of this type for a motor vehicle is known from US 2008 / 0191855 A1. This system uses wheel electronics with a pressure sensor arranged in the wheel for each wheel and receiver electronics arranged in each wheel well, which receive the signals sent by the respective wheel electronics and forward them via a data bus to an evaluation electronics unit.

[0005] The use of multiple transmitting and / or receiving antennas can improve the reception of tire pressure sensors when a vehicle is stationary. However, this leads to significantly higher system costs. Such a tire pressure monitoring system is known from US 6,985,117 B2. This system includes several stationary primary antennas and several secondary antennas mounted on a vehicle tire for transmitting electrical energy and for signal transmission. Patch antennas, arranged on a rim strip around a wheel rim, are preferably used as secondary antennas.

[0006] DE 199 26 616 discloses a tire pressure monitoring system that includes an antenna system with two antennas, in which the directional characteristic of the antenna is actively adjustable to improve reception probability. This allows reception for a specific wheel position to be improved by selectively changing the directional characteristic; however, this design does not completely eliminate shielding effects.

[0007] US patent 2003 / 0038716 A1 discloses a direct measuring tire pressure monitoring system that is combined with wheel sensors of an anti-lock braking system (ABS).

[0008] For trucks, knowing the correct tire pressure is crucial for a transport company, both before starting a journey and during extended periods of inactivity. However, with a state-of-the-art system consisting of a receiver module and an internal tire pressure sensor on or in each wheel, reliable tire pressure monitoring while stationary is not possible. If a wheel is positioned in such a way that the sensor signal is blocked by the rim and other obstructing components like the axle tube or frame parts, preventing the sensor signal from reaching the receiver module, no tire pressure reading can be transmitted. In this case, the tire pressure readings can only be transmitted again after the vehicle has started moving.

[0009] The radio reception of signals from a tire pressure sensor is therefore highly dependent on the sensor's position between the tire and rim. Firstly, reception can be reduced if the sensor's signals are attenuated by the rim's edge and rim bed. Secondly, the antenna's transmission power can be reduced by ferromagnetic material located close to the sensor, such as the steel of the rim. Thirdly, a steel carcass under the tire's tread can also significantly attenuate the sensor signal.

[0010] If the sensor signal from the tire is too weak, the probability that the signal will not be received by the receiver is very high. This increases the risk of undetected tire pressure loss and also the risk of total tire failure.

[0011] JP 2004 284396 A discloses an installation structure for a sensor unit in a wheel condition detection device for a vehicle. A sensor unit is arranged on an outer ring on a rim and within a tire. The outer ring is designed to slide on an inner ring attached to the rim. The outer ring is made of metal and has a weight section that, when the vehicle is stationary or moving slowly, orients itself downwards due to the force of gravity. The sensor unit and the weight section are arranged symmetrically on the outer ring, so that the sensor unit orients itself upwards when the vehicle is stationary or moving slowly.

[0012] DE 10 2010 037 597 discloses a tire module for vehicle tires, which is freely movable within a tire cavity of the vehicle tire on a band-like retaining element, wherein the retaining element is arranged essentially coaxially to a rim within the tire cavity. The tire module serves for tire identification, air pressure monitoring, temperature measurement, and / or measurement of mechanical stress states in the vehicle tire.

[0013] DE 103 60 780 A1 discloses a device with a sensor module for acquiring and processing a measurement signal characterizing the condition of a vehicle tire, which is permanently attached to a rim bed of the tire. US 2005 / 151375 A1 discloses a device for energy recovery in a vehicle tire.

[0014] The object of the invention is therefore to provide a tire monitoring system that is cost-effective and has high reliability.

[0015] This problem is solved by a tire monitoring system according to claim 1, and by a motor vehicle with a tire monitoring system according to claim 10.

[0016] The dependent claims include advantageous further developments and improvements of the invention in accordance with the following description of these measures.

[0017] The invention relates to a tire pressure monitoring system for a motor vehicle, in particular a commercial vehicle, wherein the tire pressure monitoring system comprises a receiver that is permanently attached in or to the motor vehicle, a belt, and an electronic module that is attached to a wheel rim of the motor vehicle by means of the belt. The belt has some slack, and its length is dimensioned such that no shielding effects occur due to the rim.

[0018] The length of the belt is chosen such that the electronic module is not obscured by a rim edge of the vehicle when the vehicle is stationary, so that no shielding effect occurs due to the rim edge and signals sent by the electronic module can be received by the receiving device without attenuation.

[0019] In one embodiment, the belt has a length that is greater than the circumference of a rim bed of the rim, such that the belt rests on the rim bed with a slippage.

[0020] In another embodiment, the electronic module is arranged in a pocket that is attached to the belt, wherein the electronic module and / or the pocket in particular have a weight by which they sag downwards when the vehicle is stationary.

[0021] In another embodiment, the electronic module includes a pressure sensor and / or a temperature sensor.

[0022] In another embodiment, the belt is designed as a rim tape, a cord or a strap.

[0023] In another embodiment, the receiving device is arranged in a wheel arch of the motor vehicle in which the wheel is mounted.

[0024] In another embodiment, a moving coil device for energy recovery and for supplying the electronic module with a supply voltage is arranged on or at the rim.

[0025] The invention further relates to a motor vehicle, in particular a commercial vehicle, which includes a tire monitoring system with a receiver that is fixed in or on the vehicle and an electronic module that is attached to a rim of a wheel of the motor vehicle by means of a strap, wherein the strap has a slippage capability.

[0026] Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below with reference to the figures.

[0027] They show: Fig. 1 a tire pressure monitoring system for a motor vehicle; Fig. 2 an electronic module mounted in a wheel according to the prior art; and Fig. 3 an electronic module mounted in a wheel according to the invention.

[0028] The present description illustrates the principles of the inventive disclosure. It is therefore understood that those skilled in the art will be able to design various arrangements which, although not explicitly described here, embody principles of the inventive disclosure and which are also intended to be protected in their scope.

[0029] In the Fig. 1 Figure 1 schematically depicts a motor vehicle 1 equipped with a tire pressure monitoring system. The motor vehicle 1 has four wheels 2a - 2d, which are arranged in a corresponding wheel housing 4a - 4d of the motor vehicle 1 and mounted on an axle in which Fig. 1 Not shown, are attached. Each individual wheel 2a - 2d is assigned a transmitting device 6a - 6d. These transmitting devices 6a - 6d can be arranged in a known manner, for example, within a respective tire, i.e., in its rubber material, and / or in the area of ​​the valve or the rim of the respective wheel 2a - 2d. Each transmitting device 6a - 6d comprises a wheel sensor designed to determine wheel-specific parameters, such as tire pressure, tire temperature, wheel rotational speed, tire tread depth, and, if applicable, other parameters.

[0030] Each of the transmitting devices 6a - 6d further comprises a circuit arrangement that pre-evaluates the information thus acquired from the respective wheel sensor and prepares it for transmission. The information determined by the transmitting devices 6a - 6d is modulated or encoded onto a transmission signal S1 - S4 and sent to the motor vehicle 1 via a wireless communication link. For this purpose, each transmitting device 6a - 6d comprises a respective transmitting antenna 8a - 8d.

[0031] To receive the transmission signals S1 - S4, the tire pressure monitoring system has four receiving units 10a - 10d on the vehicle side, each comprising a receiving antenna 12a - 12d. The receiving units 10a - 10d are located in the area of ​​the wheel arches 4a - 4d and thus in close proximity to the respective transmitting units 6a - 6d.

[0032] The tire pressure monitoring system also includes a data bus 14 and a control unit 16, which contains a central processing unit 18. The receivers 10a-10d can communicate with the control unit 16 via the data bus 14. The control unit 16, the receivers 10a-10d, and the transmitters 6a-6d are designed to measure the respective tire pressures, for example, within specific time intervals, to evaluate the measured tire pressures, and to inform a person operating the vehicle 1 if one of the wheels 2a-2d has, for example, a tire pressure that is too low. The arrangement of the receivers 10a-10d in the immediate vicinity of the respective wheel 2a-2d has the advantage that the transmission signals S1-S4 can still be received with relatively high reliability even when transmitted at low power.

[0033] A state-of-the-art transmitting device 24, attached to a wheel 20, is shown schematically in the Fig. 2 The transmitting device 24 is shown here firmly attached to a rim 22 of the wheel 20 by means of a strap 26. The transmitting device 24 is therefore rigidly fixed to the rim 22 and is thus located within the shielding area of ​​the rim 22. The transmitting device 24 comprises, in particular, a pressure sensor, a processing unit connected to the pressure sensor, and a transmitter connected to the processing unit. Fig. 2 (Not shown) , which are supplied with electrical energy, for example, via a battery integrated into the processing unit. The pressure sensor measures the current tire pressure of wheel 20, and the processing unit transmits this information wirelessly as a transmission signal in a known manner via the transmitter to a corresponding receiving unit of a vehicle.

[0034] Since the transmitter 24 is fixed to the rim 22 by the strap 26, it rotates with the wheel 20 when the vehicle moves. If only one receiver station, for example in the vehicle's wheel well, is used to receive the transmitted signal, the signal strength constantly changes while the vehicle is in motion. Furthermore, the metal used in the rim 22 causes varying shadowing effects as the wheel 20 rotates, leading to signal fluctuations and potentially signal loss. Additionally, when the vehicle is stationary, the receiver station receives different signal strengths of the transmitted signal, depending on the position of the transmitter 24 on the rim. Therefore, a tire pressure monitoring system of this type with only one transmitter and one receiver station may not provide reliable measurements in all operating conditions.

[0035] In one embodiment of the invention, in which Fig. 3 In a schematic representation, a wheel 30 has a rim 32, a tire 38, and an electronic module 34. The electronic module 34 is attached to a strap 36, which rests on the rim 32. The electronic module 34 is therefore located inside the tire 38, thus protecting it from external environmental influences. The wheel 30 is attached to a motor vehicle, for example, a truck. The electronic module 34 is part of a tire pressure monitoring system, which also includes a corresponding receiver. Fig. 3 The receiving device is, for example, arranged in a known manner in a wheel arch of the motor vehicle in which the wheel 30 is mounted.

[0036] The strap 36 rests, in particular, on a rim bed 40 of the rim 32 and has a length that is significantly greater than the circumference of the rim bed 40, so that the strap 36 rests loosely on the rim and the electronic module 34 sags downwards due to its weight when the vehicle is stationary. The strap 36 is therefore arranged, in particular, with a slippage on the rim bed 40 of the rim 32.

[0037] The length of the belt 36 is selected in particular such that the electronic module 34 is not covered by a rim edge 42 of the rim 32 when the motor vehicle is stationary, so that no shielding effect occurs between the electronic module 34 and the receiving device due to the rim edge 42 and signals sent by the electronic module 34 can therefore be received by the receiving device without attenuation.

[0038] Another advantage of the suspended position of the electronics module 34 is a more representative temperature measurement. Sensors integrated into the electronics module 34 can be used to output a temperature-compensated pressure value, e.g., calculated back to 20 °C. One problem with temperature compensation is a so-called "Hot Shutdown". If the vehicle is parked after a prolonged braking phase, e.g., after a downhill drive, glowing brake pads located near wheel 30 can cause the rim 32 to overheat significantly. This leads to a temperature sensor integrated into an electronic module, which sits directly on the rim 32, measuring a significantly higher temperature than the actual temperature of the tire 38. If a tire pressure monitoring system then compensates for the pressure values ​​transmitted by the electronic module with the incorrect temperature readings (e.g., 20 °C), incorrect pressure information can result. The high temperature can also damage the electronic module itself and, consequently, the tire.

[0039] The electronic module 34 is preferably arranged in a pocket 44, which is attached to the strap 36. It is important that the strap has some play on the rim. Thus, due to its weight, the electronic module 34 in the pocket 44 can rest against the rim 32 at the bottom of the wheel 30 when the vehicle is stationary, thereby improving the reception of signals from the electronic module 34 by the receiving device. The rim edge 42 corresponds to the shielding area of ​​the rim 32. As shown in the Fig. 3 As shown, the electronic module 34 hangs outside the shielding area of ​​the rim 32 due to the significantly greater length of the strap 36 compared to the circumference of the rim bed 40.

[0040] During driving, the electronic module 34 is permanently lifted from the rim by centrifugal force and, due to its central position in the tire cross-section, can transmit a stronger signal. This prevents shielding by the rim edge 42 even while the vehicle is in motion, and a sufficiently strong signal can be sent from the tire 38 to the receiving device.

[0041] Several design variations are possible for the strap 36; for example, the strap 36 can also be designed as a rim band, a cord, or a belt. In a preferred embodiment, the strap 36 is designed to be long enough that there is always some slippage between the strap 36 and the rim 32. However, for improved mounting, the strap 36 can also be designed to fit snugly against the rim 32, allowing the pocket 44, in which the electronic module 34 is located, to move. This would mean that the electronic module 34 might not always slide down when the vehicle is stationary, but it would still result in improved transmission performance.

[0042] The hub between the rim 32 and the electronic module 34 can also be used for energy recovery while the motor vehicle is driving - Energy Harvesting -This can be achieved by utilizing an oscillation of the electronic module 34 on the rim 32 during the vehicle's operation. This can be realized, for example, by a switching coil apparatus arranged between the electronic module 34 and the rim 32, which induces a voltage in the switching coil apparatus due to the changing acceleration due to gravity, and which can be used to operate the electronic module 34.

[0043] All examples and conditional formulations mentioned herein are to be understood without limitation to the specifically cited embodiments. The disclosure is not limited to the embodiments described here. There is scope for various adaptations and modifications that a person skilled in the art would consider based on their expertise and in accordance with the disclosure. Reference symbol list (part of the description)

[0044] 1Motor vehicle 2a - 2dWheels 4a - 4dWheel housings 6a - 6dTransmitting devices 8a - 8dTransmitting antennas 10a - 10dReceiving devices 12a - 12dReceiving antennas 14Bus 16Control unit 18Computer unit S1 - S4Transmitting signals 20Wheel 22Rim 24Transmitting device 26Belt 30Wheel 32Rim 34Electronic module 36Belt 38Tire 40Rimbed 42Rim edge 44Bag

Claims

1. Tire control system for a motor vehicle, in particular a commercial vehicle, comprising a receiving device which is firmly attached in or to the motor vehicle, a belt (36) and an electronic module (34) which is attached by means of the belt (36) to a rim (32) of a wheel (30) of the motor vehicle, the belt (36) having a slip, characterized in that the length of the belt (36) is selected such that the electronic module (34) is not covered by a rim flange (42) of the motor vehicle when the motor vehicle is stationary, so that a shielding effect by the rim flange (42) is prevented and signals sent by the electronic module (34) can be received by the receiving device without attenuation.

2. Tire control system according to claim 1, wherein the belt (36) has a length that is greater than a circumference of a rim well (40) of the rim (32), so that the belt (36) rests on the rim well (40) with a slip.

3. Tire control system according to claim 1 or 2, wherein the electronic module (34) is arranged in a pouch (44) which is attached to the belt (36).

4. Tire control system according to claim 1, 2 or 3, wherein the electronic module (34) and / or the pouch (44) have a weight which causes them to sag downward when the vehicle is stationary.

5. Tire control system according to any of the preceding claims, wherein the electronic module (34) has a pressure sensor and / or a temperature sensor.

6. Tire control system according to any of the preceding claims, wherein the belt (36) is designed as a rim strip, a cord or a strap.

7. Tire control system according to any of the preceding claims, wherein the receiving device is arranged in a wheel housing of the motor vehicle, in which the wheel (30) is mounted.

8. Tire control system according to any of the preceding claims, comprising a plunger coil apparatus arranged on or at the rim (36) for energy recovery and for supplying the electronic module (34) with a supply voltage.

9. Motor vehicle, in particular a commercial vehicle, comprising a tire control system according to any of the preceding claims.