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10.1 ACCELEROMETER AND OTHER SENSORS
The patents show some possible use of accelerometers to be inserted in the tyre; for instance to measure the revolutions, the length of the foot print or the speed; examples concerning how to analyse the signal are also reported.
US 5749984: “Tire monitoring system and method” by Michelin.
A method and system for monitoring and measuring the amount of deflection of a pneumatic tyre and the length of the contact patch are proposed. The embedded sensor device generates a signal which varies as it passes through the tyre contact patch. The sensor is mounted at the middle of the inner liner. The goal is to determine deflection, tyre speed and number of tyre revolutions.
WO 09856606: “Monitoring a tyre by acceleration measurement” by Dassault Electronique.
The concept shows an acceleration sensor that is mounted on the wheel. It is implanted in the tyre running tread or in the proximity thereof. The sensor is combined with a transmitter for energy and information.
EP 0988160: “Surveillance d’un pneuamtique par mesure d’acceleration” by Thales Systemes Aeroportes.
A system for monitoring a tyre by acceleration measurements is described (in French).
EP 1163136 and WO 015455: "Device for continuously measuring deformations in a tyre during the travel movement of a motor vehicle" by Pirelli Pneumatici.
A device for continuously measuring deformation of a tyre is proposed. A emitter of a light beam and an optical sensor are mounted on the rim and a reflector is attached in the opposite to the inner surface of the tyre. The beam of light is reflected back to the rim and detected by a light sensitive element. The intensity of the reflected light beam is detected by the sensor which provides a signal representing the deformation of the tyre.
10.2 TYRE INTEGRATION
The reported patents show some possible methods how to link the TMS to the tyre. Not only mechanical approaches, but also adhesion way or a non-contact solution - leaving the system free to float inside the rolling tyre – are documented.
As it is for practical products, the task of tyre integration seems to be one of the most difficult problems to be solved in the TMS area. It is important in fact to maintain the standard behaviour of the tyre (performance, integrity and fatigue included). Up to now no verified and tested product has been presented on the market.
US 05500065: “Method for embedding a monitoring device within a tire during manufacturing”
by Bridgestone/Firestone.
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The invention concerns a manufacturing method of a tyre, wherein a monitoring device is embedded within the tyre during its manufacture. The method consists of mounting the device by means of a dowel. When the device is covered with layers of the inner liner, the dowel is removed and produces an aperture in order to contact the embedded monitoring device.
US 6217683: “Monitored vehicle tire and monitor retainer assembly” by Michelin.
The invention provides a tyre monitor retainer assembly. A module which monitors tyre information is supported by a rubber ply affixed to the inside surface of the tyre.
US 6452650: “Tire module attachment mount” by Michelin.
A method to affix a module to the inner surface of the tyre by the help of a special rubber ply is described. The module is used for monitoring tyre information (not specified in detail). The module is mounted to be removed, exchanged, etc. A damping element may also be used to limit the movement and vibrations of the module.
US 6386254: “Device to encapsulate a substrate containing sensitive electronic component“ by Bridgestone/Firestone.
The patent describes a device for encapsulating a pressure sensor in combination with an antenna.
The invention takes care that the pressure sensor is prevented from being clogged with the encapsulating material by a damming element and that the connection between the body and the antenna holds the sensor in a floating position.
US 6435020: “Method for allocating tire pressure control device to wheel position in a tire“ by Continental.
A method for allocating tyre pressure control measurements to wheel positions using some kind of a central clock is proposed.
US 6360594: “Non attached monitoring assembly for pneumatic tyre” by Bridgestone/Firestone.
A very original method to place a monitoring assembly inside a tyre is proposed. The tyre is filled partly with a liquid. The monitoring assembly is encapsulated within a spherical protective body and is swimming on the surface of the liquid.
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10.3 ANTENNA
The material used for an antenna can be metallic, rubber like or plastic. The antenna can be located inside the tyre, outside the tyre or embedded in the tyre. The antenna can be used to transmit the signal or also to receive electrical energy (e.g. for a transponder or similar devices).
EP 1049196: “Dipole antenna for tire tag” by Bridgestone/Firestone.
A monitoring device for at least one property of a tyre is proposed. The device is located in the side wall. It includes a sensing element and a dipole antenna for communication. The dipole antenna is disposed perpendicular to the reinforcing cords in order to maximise the probability of signal propagation through the side wall.
WO 9929523: “Antenna for radio transponder“ by Goodyear.
The patent describes an antenna which is embedded in a non-conductive elastomeric material located within the toroidal region of a pneumatic tyre or on the radial outer side of the wheel rim.
The device includes a radio-frequency transponder and optional sensors placed on an integrated circuit chip. The transponder has at least the capacity to transmit data relating to tyre or wheel identification.
EP1048494 (similar to EP1048493): “Combination monitoring device and patch for a pneumatic tyre and method to installing the same with a coupled antenna” by Bridgestone/Firestone.
The patent describes the combination of a monitoring device and a patch to monitor the conditions of a tyre. The patch is adapted to carry the monitoring device and to mount the monitoring device on the inner liner of the tyre. The focus of the invention concerns the assembling and the electrical contact of the antenna and monitoring device.
WO 9929522 (similar to WO 9929523): “Pneumatic tyre with antenna for radio transponder” by Goodyear.
A device is embedded in substantially non-conductive elastomeric material located within the toroidal region of a tyre. It is coaxially positioned with respect to the tyre or wheel and is embedded in the tyre at its equatorial plane. The device contains a RF transponder, including an integrated circuit chip and optical sensors.
WO 02068224: “Monitoring device and tire combination” by Bridgestone/Firestone.
The patent proposes a combination of an antenna and a monitoring device (sensor). The antenna is mounted on the tyre side wall outside the body cords of the tyre or it is embedded in the body of the side wall. The sensor is located inside the tyre opposite to the antenna. The connection between sensor and antenna may be a plug and socket connection or capacitive coupling.
EP 1262339 and US 6518877: “Pneumatic tire monitor” by Goodyear.
A system for monitoring pneumatic tyre conditions for one or more tyre-wheel assemblies is described. The system is mounted on a vehicle preferably in combination with a tyre pressurising and regulating device. The patent focuses on a data transmission system using an arrangement of different antennas.
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10.4 POWER TRANSMISSION / GENERATION
The patents family referring to power transmission is very large and many solution have been proposed. The solutions are focused mainly to avoid the use of the battery inside the tyre and transmitting the energy from the vehicle to a system inside the tyre. For power transmission it is necessary to use an antenna on the vehicle which is placed close to the tyre and another antenna inside the tyre. The more significant problems are the size of the antenna, the possible locations for antenna integration inside the tyre and the electrical connection between the antenna and the electronics. Most patents referring to power generation at the tyre are using piezo electronics.
US 5483827: “Active integrated circuit transponder and sensor apparatus for sensing and transmitting vehicle parameter data“ by Computer Technologies Inc.
An active integrated circuit transponder with on-board power supply is mounted in or on a vehicle tyre. A pressure sensor, a temperature sensor and a tyre rotation sensor are mounted on a substrate along with the integrated circuit transponder chip, the power supply and the antenna. Upon an interrogation signal from a remote source, the transponder activates the sensors to sense and to transmit the signals.
WO 0180327: "Piezoelectric Generator for sensors inside vehicle tyre” by Pirelli Pneumatici.
A system for generating electrical energy in a vehicle tyre is proposed. It comprises at least one piezoelectric element which generates energy when it is deformed. The piezo element preferably comprises a coaxial cable extending along e.g. a straight path of the tyre circumference. The element is connected to an electrical circuit that is applied to the tyre.
10.5 GENERAL ASPECTS OF TOTAL SYSTEM
This area covers a number of possible ways to manage the data and to arrange the entire system.
Potential methods of data management are e.g. to analyse the data inside or outside the tyre, use of single tyre data or co-use of tyre data of all tyres. together. It is possible to set up a digital or an analog data analysis. A large number of possible algorithms to be used for data interpretation and processing is proposed. Many patents show a solution based on a combination of some of the possibilities.
EP 1263616 and WO 0168388: “System, tyre and method for determining the behaviour of a tyre in motion” by Pirelli Pneumatici.
The patent concerns a system for the continuous determination of the interaction between tyre and the ground during the movement of the vehicle. The sensor is located at the middle of the inner liner of the tyre and comprises an elongate piezoelectric element, which generates a signal during the rotation of the tyre. The sensor is associated with processing means.
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WO 0108908: “Method and System for controlling the behaviour of a vehicle by controlling its tyre“ by Pirelli Pneumatici.
The invention relates to a method, a system and a pneumatic wheel for measuring the deformations of the casing of a tyre in operation, for the purpose of taking appropriate corrective action on the vehicle driving control system. More specifically, the method consists of the following steps: measuring the extent of the characteristic deformations of the casing profile of at least one tyre at a given inflation pressure, comparing the values of these characteristic deformations with stored values and generating signals from the difference for devices which control the vehicle behaviour.
US 5559484: “Data logging tire monitoring with condition predictive capabilities and integrity checking“ by Epic Technologies.
A device for sensing a condition of a non rotating pneumatic tyre mounted on a rim is described.
The device comprises a housing, a band for mounting the housing to the rim, a sensor for monitoring the condition of the tyre and circuitry operatively connected to the sensor for generating radio signals to transmit data. The system includes data logging capability for storing time series tyre condition information for use as a historical log and other information.
US 6448891: “Wireless remote tire parameter measurement method and apparatus“ by GeoMatt Insights.
The proposed system allows a tyre pressure control without any monitoring device located in the wheel. Basic information are acquired from the acoustic signature of the rolling tyre. A processor is used to calculate the pressure values. The calculation takes into account a set of reference parameters and warnings are generated.
WO 02053429: “Method and system for controlling and / or regulating the handling characteristic of a vehicle“ by Bosch.
The invention relates to a system for monitoring the properties of at least one tyre. The system includes sensors and a device for storing data. A method for monitoring the properties of a tyre is proposed The information may be used to improve the performance of driver assistance systems.
EP 1245412: “A system and an apparatus for monitoring a tire condition value in a pneumatic”
by Goodyear.
A system for monitoring at least one tyre condition is proposed. The tyre is associated with a passive electronic tag which is responsive to an interrogation signal transmitted from the vehicle to the rotating tyre. The patent describes the data transmitting system in some detail.
US 0095253: “Vehicle stability control system with tyre sensor assembly” by Siemens VDO Automotive.
A vehicle control system tyre characteristic information such as tyre pressure and temperature during vehicle operation is presented. Variances in tyre temperature and pressure which can effect the tyre radius are used to calculate vehicle speed and individual tyre rotation speed. This speed data are used for generating control signals for vehicle control systems such as ABS, traction and stability control systems.
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US 6518876: “Determination of Wheel Sensor Position Using Radio Frequency Detectors in an Automotive Remote Tire Monitor System" by Schrader-Bridgeport International.
The patent describes a RF data transmission system (tyre - chassis). Data from a plurality of tyre monitors (sensors) located at wheels of a vehicle are transmitted to a RF receiver on the vehicle.
The transmitted data contain both the sensor data and the transmission indication. The system is used for an automatic update of the position of the tyre monitors on the vehicle.
US 6340930: “System and methods for monitoring a condition of a vehicle tire“ by TRW.
A system for monitoring a condition of the tyre (condition not specified) is a component of the proposed concept. The patent contains a radio frequency based signal transmission from the tyre- based unit to the vehicle-based unit. Only one receiver unit is used on the vehicle. A method to identify the tyre position corresponding to reception success rates is described.
10.6 CONCLUSION
The overview on patent applications in the field of an intelligent tyre/wheel system can be summarised as follows:
• Many areas are covered such as subsystems or total systems and a wide range of technologies are used for the proposed solutions.
• Many inventors or companies are active in this field.
• There is a high activity on patent applications and it is still increasing.
These aspects show, that on one hand there is a high interest in this field but on the other hand there is a big gap between the proposed systems and series products which are available on the market up to now, with the exception of TPMS. This gap is a reason why further research activities are needed for the development of an intelligent tyre/wheel system. This research activities can benefit from a high innovation rate in the fields of electronics/microelectronics, radio communication and power generation technologies. The innovations and new technologies resulting from these activities are supporting the development of e.g. sensors, wireless data transmission and batteryless power supply that are key subsystems for an intelligent tyre/wheel system. It can be concluded that there is a promising perspective to set up a successful product by the help of research in the APOLLO project.
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