GB529012A - Improvements in and relating to control mechanism for internal combustion engines - Google Patents

Abstract

529,012. Fluid pressure-servomotor-control systems. DUNCAN, H. L. May 19, 1939, No. 14985. [Class 135] The timing adjustment of the admission valve of an internal combustion engine is dependent on fluid pressure set up by an engine driven pump modified by the varying pressures in the induction pipe. The crank-shaft a or the cam shaft b is formed with an extension 10 surrounded by a bush 17 having internal and external straight and inclined splines associated with corresponding grooves in the extension 10 and one of the gear-wheels 19, 20. Axial movement is imparted to the bush 17, with consequent relative angular movements of the gears 19, 20, by fluid pressure on a piston 18 integral with the bush. A pump 22 in the crankcase and driven from the crank-shaft circulates oil by way of a pipe 29 to the chamber behind the piston and thence back to the crank-case by openings 30 and passages in a brake disc 31. The rate of circulation is controlled (1) by the shape of the openings 30 and the degree to which they are uncovered by the piston 18, (2) by a needle valve 27, (3) by the induction-pipe pressure acting through a pipe 42 on a piston 36 carrying a brake block 37 which under the action of a spring 40 tends to engage the disc 31. Relative movement of the disc against the action of a spring 32 uncovers an additional port leading back to the crank-case, which opening is covered by the hub of the disc when the block 37 is out of engagement. In a modification the needle-valve 27 is replaced by a valve close to the cylinder 13, this valve being controlled by Bowden mechanism from the dash-board.