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Knock-induced pressure waves in the combustion chambers of spark-ignited engines cause the engine block to vibrate at the same frequencies. These vibrations have different amplitudes at different locations on the engine block. This paper describes a project to find a location on the engine block where the amplitudes of the knock-induced vibrations are high enough to use in a knock control system. To find this location, six piezoelectric knock sensors were located on suitable regions of the engine block. Data were collected from the sensors at both knocking and non-knocking conditions using a high speed data acquisition system. After the data were transformed into the frequency domain, comparison of the knocking and non-knocking condition data indicated the frequencies and amplitudes of the knock-induced engine block vibrations. The location where knock-induced vibrations were transferred with the greatest amplitude was determined.

A miniature sensor for detecting cylinder misfiring based on the principle of magnetostriction has been developed for on-board use in production vehicles. The sensor induces a magnetic field in the engine crankshaft, and via Faraday's law, obtains a signal directly related to the strength of the field. Due to magnetostriction, the field strength changes as the stress in the crankshaft changes during each cylinder firing. The output signal of the sensor is therefore high when any given cylinder fires and low when it misfires, permitting ready determination of misfiring. Tests on a manual transmission vehicle have shown that a single sensor can detect misfiring in one or more cylinders at any non-negative torque and any speed, as well as on very rough roads. Other uses for the sensor, such as knock detection, are anticipated.