Abstract: Pressure sensor for measurement of gas pressure in a cylinder of a combustion engine, including a tube shaped in cross section as an hourglass. In the axial direction the tube consists in part of a section connected to the cylinder and open to the cylinder, in part of a measuring section and in part of a final section the end of which is closed. The measuring section of the tube is shaped so that in the tubes axial direction two parallel measuring surfaces are established against which are two beams connected to force transferring yokes arranged to influence force measuring organs for the determination of the force with which the gas pressure influences the parallel measuring surfaces of the tube. In this pressure sensor and other embodiments the influences of temperature fluctuations and any shunting effects of the material of the measuring tube are reduced to a minimum.

Abstract: A magnetoelastic force transducer which is compensated for sensitivity drift is provided with a measuring transducer and a reference transducer (1) of the same material. In its simplest form the reference transducer may consist of a toroid. The two transducers are arranged in good thermal contact with one another. The reference transducer is arranged with a winding (2) for excitation with a current which at each moment is proportional to the supply current of the measuring transducer, and with a winding (3) for delivering a reference signal (U.sub.r) proportional to its magnetic flux. The output signal of the reference transducer is rectified in a phase-sensitive rectifier, the output signal of which is compared with a constant reference voltage. The deviation controls the phase position of the control voltage of the rectifier in such a way that the output signal of the rectifier is caused to correspond to the reference voltage.

Abstract: A force measuring magnetoelastic transducer includes a core of magnetostrictive material with apertures, in which excitation and measuring windings are arranged, and between which a measuring zone is formed, in which the dominating part of the magnetomotive force is consumed and in which the stress therefore determines the output signal of the transducer. The core further includes apertures for controlling the force flux, which are so arranged that some measuring zone portions are substantially subjected to compressive stress and other measuring zone portions are substantially subjected to tensile stress when a force is acting on the transducer. Means are provided for exciting the transducer with an alternating current of such magnitude that the signals generated by said compressive and tensile stresses, within a predetermined range of load, show deviations from linearity with negative sign for compressive stress and positive sign for tensile stress.