A tire pressure measuring system based on surface acoustic wave (SAW) sensors is presented. Since SAW sensors are powered by the energy of the RF field no battery is required, which is a major drawback of conventional systems. A successful combination of a SAW reflective delay line with a capacitive pressure sensor is shown. With a new way of matching the sensor impedance to the SAW reflector impedance both a high signal-to-noise ratio and a high signal dynamic are achieved which supports accurate signal evaluation. A prototype of a tire pressure sensor unit is presented.
In this paper, the possibility for acquiring dynamic characteristics of pressure sensors is described. A dynamic pressure generator is assembled with two opposing loudspeakers and a confinement ring in-between. The ring has several openings for connection of the evaluated and reference pressure sensors. Frequency, waveform and amplitude control of the generated pressure were achieved by applying an amplified function generator signal to the loudspeakers. Since general-type audio loudspeakers were used, the solution is cost-effective as well. The background of our theoretical model,...
We have developed a system for the amplitude measurement of periodic square-wave pressure by measuring the change in refractive index of air. Using a differential interferometer and a pressure cell whose capacity was less than 5 cm³, the change in the optical path difference between the reference and measurement paths was measured when square-wave pressure was applied in the cell. A rotating valve was used to vary the pressure in the cell. For the measurement in the amplitude range from 10 kPa to 100 kPa as gauge pressure, the pressure amplitude and the optical path difference were...
The paper presents the prototype of the membrane pressure gauge with optoelectronical conversion. The main parts of the system are polished metal membrane, plastic (PMMA) 2 m long optical fibres, and the box containing optoelectronic components (laser diode module, beam splitter, photodetectors and op. amps). Pressure changes causing membrane displacement modulate the laser beam conducted by incoming optical fibre. Modulated and reflected beam is conducted through the outgoing optical fibre to the optoelectronical assembly where it is converted into the voltage proportional to the pressure....
The majority of high volume sales gas metering is carried out using orifice plate systems at high static pressures. The system will include one or more differential pressure sensors that will require calibration at the working static pressure in order to maintain traceability at an acceptable uncertainty. Calibration is generally carried out using a twin-post deadweight tester, but some components of uncertainty are unique to each instrument and are difficult to assess. This paper demonstrates a practical approach to the characterisation and uncertainty analysis of a twin post deadweight...
An iterative method for the reconstruction of the oscillating-pressure measuring signal at the inlet of the small diameter cylindrical tube is presented. This method requires a good mathematical model of the flow phenomena in the tube. The theoretical model of the phenomena and its experimental correction are described. The limitations and the application range of this reconstruction method are discussed.
This paper presents a simplified model for the evaluation of the measurement uncertainty of a pressure balance (Type V1600/4D, manufactured by Pressurements, Ltd.) used in our pressure calibration laboratory as a standard pressure balance for gauge and differential pressure measurement. The gauge measuring range of this gas-operated balance runs from a nominal pressure of 20 Pa to 16 kPa and its minimum differential pressure measurement is 5 Pa. The results for measurement uncertainty obtained from the model are based on calibration data provided by the accredited calibration laboratory. In...
The paper reports some new results obtained in the theory of Electromagnetic induction flow measurement. These include the extending of the present theory to multiphase application, measurement of dielectric fluid and flow pattern reconstruction.
The nonlinear phenomenon of the vibration of a rotating machine is studied experimentally and numerically. The rotating part of the machine has a contact surface with static elastic surface. Vibration of the rotating part itself without any contact to the surface is considered as linear problem. Inviting frictions on the contact surface causes nonlinear phenomena, which cannot be explained by linear concepts, such as multiple attractors, chaotic orbits and bifurcation behavior. The experiment is focussed the influence of the friction on the behavior of the rotating part. With the help of the...
It is necessary to make constructional changes on the dies for manufacturing of tubular mechanical elements by forward and backward cold extrusion in order to maintain high dimensional precision. The radial elastic deformations are controlled by inserting single or double shrink fit within the die. This arrangement decreases and homogenizes tangential stresses in the die and shrink rings and improve die fatigue life. A conventional way of calculating stress and deformation for this kind problem is Lame Equations. In this study, the effect of dimensional changes of die and shrink rings on the...