KOLBEN-ZYLINDEREINHEIT ZUR ATEMGASFOERDERUNG ALS ZYLINDERKONDENSATOR FUER DIE HUBSTRECKENMESSUNG

摘要

A piston-cylinder unit as a delivery device for the respiratory gas in a ventilator, having a rolling membrane rolling between the piston and the cylinder, is to be improved in such a way that a simple measurement apparatus which measures accurately, reproducibly and absolutely and does without wear parts for the displacement which changes with every piston stroke can be used for measurement of the displacement. For this, the invention provides that at least part of the cylinder wall (29) and the piston wall (28) are designed as electrically conductive plates of a cylinder capacitor and that the rolling membrane (9) covers as dielectric the overlapping wall parts of the piston (4) and the cylinder (1). The capacitance of the capacitor which changes during the stroke movement is used for measurement of the displacement.