Search Results

Imbalance between cylinders is a major concern of a proper operation of reciprocating engines. An engine reliability and performance envelop, including life span, fuel consumption and emission, are strongly affected by an improper operation of the cylinders. To improve the engine quality, there is a strong need for a closed-loop control system to manage the amount of fuel injected to each individual cylinder. An advanced system to detect imbalance related faults in reciprocating engines which is based on the analysis of the engine's mechanical vibrations have been developed. The system is based on a firm theoretical background that provides a fundamental relation between the engine's vibration pattern and the relative characteristics of the combustion process in the different cylinders. With a single accelerometer mounted on the engine's block, online information related to the combustion process in each cylinder is provided by the system.

A new hydraulic cam follower with variable valve timing (VVT) properties is described. Experimental results show that the point of closure of the valve may be delayed as a linear function of engine speed without external control. No other parameter of the valve event is modified by the device. An obvious application is the control of intake valve timing for engines with a wide speed range, where the point of valve closure could be scheduled with engine speed in order to maximise the trapped mass, hence improving the torque curve at low and high speeds. The device is considered for application to the Ford 2.5 litre DI diesel engine, where it may be used to retard inlet valve closure from close to bottom dead centre (BDC) at cranking speed to 50-60 deg after BDC at rated speed.