ENGINEERING SOLUTION ON COMPENSATION OF THE COMPLEMENTARY TEMPERATURE ERRORS IN THRESHOLD PRESSURE DIFFERENCE DIAPHRAGM SENSORS

Abstract

Background. The threshold pressure difference diaphragm sensors are widely applied in the engineering systems because of their reliability. To ensure necessary features such sensors have to possess: high tightness of welded joints of a design; glass-to-metal seals; presence of bellows made of both fast response and high conductivity materials. Materials and methods. To meet the above requirements the body parts of the threshold pressure sensors, which size variations cause shifting of diaphragms center, are expediently to be made of kovar 29NK-VI GOST 10994-74 guarantying high weldability and impermeability of soldered joints with glass S48-2 OST 11 027.010-75 due to consistency in linear thermal extension coefficient (LTEC). Diaphragms are made of cold-rolled beryllium bronze bands BrBNT 1-9, BrB2, GOST 1789-2013, providing fast response and good weldability with kovar-made body parts and also high conductivity because the electric circuit is designed passing through the diaphragms. Pins in the center of the diaphragms have also to be made of beryllium bronze. Identical materials for both diaphragms and pins guarantee contacts reliability for example by spot laser weld. Results and conclusions. Notable difference in the LTEC of kovar and beryllium bronze within specified temperature range entails design response for the threshold pressure sensors to compensate inevitable temperature error, especially in operation under wide thermal load of the environment. The temperature is the most significant of physical factors (vibration, linear acceleration) from the error standpoint.

Keywords

• threshold pressure difference sensor
• diaphragm sensor
• contact system
• temperature error
• temperature error compensation