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The injection rate meter based on W. Zeuch's method was improved to meet the recent requirement for precise measurement of the multiple injection rate and amount in CDI (Common rail Direct Injection) diesel engines. A pressure sensor with a high sensitivity was added to measure the small pressure increase due to the pilot injection and after injection. At the same time a flow meter having a high accuracy was installed in the discharge pipe line to obtain a correction factor to the modulus of elasticity of volume. As a result it became possible to measure the multiple injection amount at an accuracy of ±0.2mm3/stroke in a range up to 40mm3/stroke.

A new method to measure accurately the compression ratio of automobile engines in the manufacturing line is proposed. To determine the compression ratio of an engine, the cylinder volume at a piston position is measured with a detecting probe which is featured with a pressure sensor of high sensitivity and a micro piston driven by an electromagnetic coil. The probe is attached to the cylinder head at the spark plug hole. The air in the cylinder at TDC is compressed sinusoidaly at a frequency of 70Hz by the micro piston with a diameter of 5mm. The volume at TDC can be determined by detecting the pressure change caused by the compression by the micro piston. In this report, the principle of the method is described and effects of geometry of the chamber space and other parameters on the measuring accuracy are discussed. Polytropic exponent of the pressure change was found most crucial in this method.

An experimental evaluation of the reliability of the Zeuch's method was carried out. The following were derived: 1) cavitation limits the minimum back pressure available; 2) the injection rate measured by the Zeuch's method agrees with that by the W.Bosch's method; 3) the effect of dynamic pressure of the injected fuel jet has a negligible effect on the pressure sensor which is attached to the chamber wall; and 4) the high-frequency noise after the end of injection observed in the Zeuch's measurement can be effectively removed by either a low-pass filter or an inverse Fourier transform processing.

A new instrument for the measurement of fuel injection rate in diesel engines was developed. The instrument, whose measurement principle is based on the Zeuch's method, i.e., the constant volume method, incorporates a device for the precise calibration of the volume elasticity of the fuel. This instrument was proved experimentally to have a capability of measuring injection rate with ± 1% accuracy up to an injection pump rotating speed of 2500rpm.