Abstract: An internal combustion engine has n member of cylinders, a piston in each cylinder connected to a crankshaft (2), each piston being in phase or out of phase with the others by A.degree. or a multiple thereof (A=720/n), cams for actuating inlet and exhaust valves to each cylinder, and a cam drive mechanism (5) which rotates the cams in phased relationship with the crankshaft (2) to open the valves in sequence for a desired angle of rotation of the crankshaft. The cam drive mechanism also includes means for combining the rotational movement of the cams with a phased oscillatory movement of the camshaft (3) and cams of variable amplitude about the axis of rotation at a frequency f times the crankshaft frequency so that over the period which the valves are opened and/or their timings variable, f has the following values:f=2n when the number of cylinders n=1;f=n or n/2 when n=2;and f=n/2 when n=3 or more. The selection of the frequency of the oscillations allows all the cams to be mounted on the same camshaft.

Abstract: The invention is concerned with a desmodromic valve operating mechanism, i.e. one in which the valve is mechanically closed instead of relying on the action of a spring. The valve operating mechanism comprises a cam 20 driven in synchronism with the engine crankshaft. A cam follower 18 is acted upon by an opening profile 22 of the cam 20 and serves to move the valve 10 in an opening direction. A movable closing member 26 has two profiles 24, 28. The first profile 24 interacts with the cam 20 and the second 28 with the cam follower 18. Closure of the valve is effected by the opening profile 22 of the cam 20 acting on the first cam profile 24 of the closing member 26 to move the closing member 26 in such a direction that the second cam profile 28 of the closing member 26 acts on the cam follower 18 to close the valve 10.

Abstract: An internal combustion engine has n member of cylinders, a piston in each cylinder connected to a crankshaft (2), each piston being in phase or out of phase with the others by A.degree. or a multiple thereof (A=720/n), cams for actuating inlet and exhaust valves to each cylinder, and a cam drive mechanism (5) which rotates the cams in phased relationship with the crankshaft (2) to open the valves in sequence for a desired angle of rotation of the crankshaft. The cam drive mechanism also includes means for combining the rotational movement of the cams with a phased oscillatory movement of the camshaft (3) and cams of variable amplitude about the axis of rotation at a frequency f times the crankshaft frequency so that over the period which the valves are opened and/or their timings variable, f has the following values:f=2n when the number of cylinders n=1;f=n or n/2 when n=2;and f=n/2 when n=3 or more. The selection of the frequency of the oscillations allows all the cams to be mounted on the same camshaft.

Abstract: The invention relates to an induction manifold for a fuel injected internal combustion engine which comprises a rigid plenum chamber, intake pipes extending from the plenum chamber to the individual engine cylinders, and extensions of the individual intake pipes disposed within the plenum chamber. This construction enables the manifold to be tuned without occupying excessive space in the engine compartment.

Abstract: The invention describes a control system in which open loops control the mixture strength and spark timing by means of look-up tables (14, 12) stored in a computer and a closed loop (16, 18, 20, 24) with much greater response time corrects the air fuel ratio to compensate for long term drift in the open loops under the control of an ionization sensor sensitive to the duration of the burn period. The ionization sensor output is used only in operating ranges where its output accurately reflects the burn period duration.Consequently, the high speed response of an open loop is achieved at the same time as the long term stability of a feedback loop sensitive to the burn period duration.

Abstract: The invention relates to a method of engine control, which comprises firing a weak spark through the spark gap, measuring the current through or voltage across the electrodes following the weak spark, analyzing the voltage or current to derive a prediction of the flame propagation speed and subsequently firing a stronger spark through the spark gap to ignite the charge, the timing of the stronger spark being varied in dependence upon the prediction of the flame propagation speed.

Abstract: The invention relates to an ignition system in which a parameter of the charge in a cylinder prior to ignition is measured in order to predict the burning characteristics of that charge and the timing of the spark for igniting that charge in the same cycle is varied in dependence upon the measured parameter in such a sense as to reduce cycle to cycle variations in the engine output torque. A hot film anemometer integrated into the spark plug provides a measurement of the charge velocity, this being one parameter which can predict the burning rate of the charge.