轮胎压力监测中英文资料外文翻译文献.doc

轮胎压力监测 中英文资料外文翻译文献参考文献Monitoring the Tire Pressure at Cars Using Passive SAW SensorsAlfred Pohl 1, G. Ostermayer }, L. Reindl 2, F. Seifert1) Applied Electronics Laboratory, University oETechnology, Gusshausstrasse 27, A-1040 Vienna, Austria2) Siemens Central Research Lab., Otto Hahn Ring 6, D-$1739 Munich, GermanyAbstract：In our paper we present the application of surface acoustic wave (SAW) sensors to the continuous manitaring of the tire pressure in road vehicles. With these, the tire pressure can be read out in every phase of driving. We show the implemented prototype setup for measurement of the tire pressure, the applied SAW sensors, improved versions and the interrogation setup. The problems in practical application are discussed. Experimental results measuring the tire pressure during test rides are presented. INTRODUCTIONOperating a road vehicle, a malfunction of the tires in motion due to a tire puncture can cause serious accidents and endanger human life. Furthermore, nowadays manufacturers of cars try to save the spare wheel in vehicles. Usually it only costs weight and space, therefore it yields a higher fuel consumption,although it will be required less than one time in more than ten years of a car's life. This only can be done, if the air pressure in the tires can be measured even during driving. Currently used sensors contain active components, powered by a Lithium battery. The mass of these sensor assemblies is about 20 grams causing high dynamic load. A few years ago,wirelessIy interrogable SAW devices far sensor applications were invented. [1，2, 3]. Using an one port SAW delay line connected to an antenna only,an RF interrogation signal is fed into and the sensor response,carrying thesensor information is retransmitted wirelessly to the interrogator. These sensors are capable for measurement of temperature, mechanical load, force and displacement, etc. The advantage is, that SAW sensors are totally passive devices and contain neither power supply nor semiconductors. They withstand temperatures up to several hundreds of degree centigrades, their lifetime is much longer than that of battery powered systems.Further,in vehicles strong electromagnetic pollution is generated by ignition systems etc.SAW sensors operate without risk of damage even in rough environments. First we discuss pressure measurement employing SAW sensors with wireless interrogation.We present some types of sensor assemblies and the interrogation system.Next we discuss the implementation into thecar and thenwe present experimentally results.Finally a brief summary concludes the content of the paper.SAW PRESSURE SENSORSThe electrical behaviour of a passive SAW pressure sensor always is that of a one port delay line with multiple reflectors or a resonator,respectively. In the delay linecase,the interrogator transmits a burst signal,the sensor responds with a chain of bursts,one for every reflector arranged at the substrate's surface.The differential delay between two or more response signals is evaluated.To measure some physical value,the parameter has to be converted into a change of sensor's surface length or surface acoustic wave's velocity,respectively.The delay ri of the response of areflector i is the ratio of SAW propagation length Li on the substrate's surface and propagation velocityv,.Affecting the sensor with a measurand causes a scaling of the sensor's response to be observed as individual delay shifts Ari of the response signals si originating frotmhe reflectors i.Mechanical measurands can be collected by loading the sensor mechanically.Apart from stretching and compressing,utilized for wireless measurement of torque,etc.the SAW sensor's substrate can be bent.Pressure can affect the sensor by bending a membrane,shifting the edge of a sensor fixed on theother side.Here the sensor is loaded to be bent due to a shift of the center of a membrane loaded by the pressure.On the other hand the sensor can directly be fitted to the membrane or a piezoelectricmembrane representing the SAW substrate can be used.Figure 1 shows these methods. Fig.1:a)Membrane converting pressureto shift bendingthe SAW sensor(SAWS)b)SAW sensor fitted to the membraneThe next step is to cover the sensor membrane by a cap consisting of a spacer frame and a quartz cover plate.This yieldsanintegratedpressure chamber SAW sensor[4](fig.2). Fig.2:Integrated pressure chamber SAW sensorThecover protects theSAW generating metallic structure from oxidation and the surface from dust.The cavity can befiIledwith a gas at reference pressure.If the cavity is evacuated,absolute pressure values can bemeasured.Measurement is made byinterrogationusing simple RF burst signals.The response impulses are evaluated in magnitude and phase.Bending the membrane due to pressure loadyields a phase shift of for instance 100 degree for lo4 Pascal.With this theairpressure 。