Take a pressure sensor, manufactured in millions of pieces each year for automotive applications, add a special 4/20 mA interface for industrial applications and you have a new pressure sensor that despite its high quality is most cost effective as well. This is EBV Elektronik’s procedure in developing its latest product, Titan. With Sensata Technologies EBV Elektronik finally found its partner to accomplish the Titan project. Sensata produces 75 million pressure sensors in capacitive ceramic technology per year for the automotive industry.
Ceramic as a base
Since 1985 Sensata has manufactured pressure sensors based on its ceramic technology. In an automobile these sensors are used in many different places with a pressure sensor for the air conditioning’s compressor loop in a car being the first application. Enhanced versions of this ceramic-based pressure sensor meanwhile are present in automatic gearboxes, fuel applications for low pressure systems (diesel) or for measuring oil pressure.
The sensor’s basis element comprises of ceramic substrate 3 mm thick, and a thin, flexible ceramic membrane with thickness of about 0,6-1,2 mm. The ceramic membrane is attached to the substrate using a glass bonding process. Sensors with different pressure ranges distinguish themselves through membranes with different thickness as well as electronic calibration. On both ceramic parts there is a thin gold layer that is connected to the electronics via contact leads. Both gold layers form a capacitor with its capacity changing as a function of pressure on the membrane: capacity is in the 15 pF range.
Using a proprietary charging/discharging process Sensata evaluates the change of capacity relative to a reference capacitor to generate an output voltage°C. Also in the upper and lower pressure range a calibration is conducted. All these measures are analog without using digital electronics. In manufacturing as well as in the field this process has proven to be extremely stable: within the core range the sensors are linear.
Titan pressure sensors equipped with an industrial output interface have been developed to satisfy customer requirements other than automotive. As a result the sensors can also be used in process automation systems and other applications. In this case the complete 4/20 mA sensor solutions are those Titan products that are marketed by EBV as part of its EBVchips activities.
Currently those EBVchips pressure sensors are available in brass versions for the four pressure ranges 0-10 bar, 0-16 bar, 0-20 bar and 0-35 bar. Also available are variants in plated steel for the 0-46 bar range. At present the pressure sensors are classified according to IP65, IP67 and IP6K9 (all with cable).
Because the sensor is powered via the signal line, the Titan sensors only use two connection lines having the relevant length for usage in harsh industrial environments where EMC is an issue. The industrial pressure sensors are immune to electrical interferences of up to 30 V/m.
Across the whole temperature range of -20 to 100°C the measurement error is less than 2%. At 25°C the measurement error across the entire pressure range is only 0,75% – this applies for more than 10 million specified pressure measuring cycles.
Vibrations up to 10 g do not harm the pressure sensors. In all cases the UL and RoHS compliant CE certified sensors make their measurement result available after a response time of 10 ms via the IP6K9 rated Delphi-Packard connector on the output.
For more information contact EBV Electrolink, +27 (0)21 402 1940, [email protected], www.ebv.com
| Tel: | +27 11 236 1900 |
| Fax: | +27 11 236 1913 |
| Email: | [email protected] |
| www: | www.ebv.com |
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