In hydraulics and in many areas of process technology, pressure sensors, i.e., devices for determining pressures, in particular pressures above 50 bar, play a large role. In automotive engineering in particular, devices of this type are used in different systems, for example, in the fuel direct injection and the electronic stability programs. Usually, so-called piezoresistive high-pressure sensors are used here, which have a particular accuracy and robustness, and are manufacturable at relatively low cost.
In the case of piezoresistive pressure sensors, strain-sensitive electrical resistors are located on a suitably configured steel diaphragm and interconnected to form a Wheatstone bridge. A pressure to be determined is applied to the steel diaphragm and causes deformations of the steel diaphragm. Thus, material strains of the resistors on the surface of the diaphragm may occur. The resistors are situated in such a way that these strains or compressive strains are detectable. A resulting detuning of the Wheatstone bridge, which is also called a resistance bridge, is at small diaphragm deflections of the steel diaphragm proportional to the applied pressure and may be evaluated by suitable electronics.
Patent document DE 10 2009 025 486 A1 discusses a two-part pressure sensor, whose two parts are fixed to one another by a weld seam. The first part is a housing including an outer thread which does not come into contact with the fluid whose pressure is to be determined. The second part includes a measured section, whose deformation is measured on the basis of the pressure to be determined and is evaluated to determine the pressure to be determined.