New Idea to Save Fuel
Page 47
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AMEANS whereby the compression ratio of an engine can be maintained at an optimum value in relation to the degree of throttle opening has
been a constant aim of inventors. If this could be achieved, the fuel consumption of the average petrol-engined vehicle would be improved by over 50 per cent., whilst the maximum power output at rotational speeds above the speed at which maximum torque is developed would be increased.
• A suggested method of achieving this is by the use of a telescopic connecting rod designed so that its effective length automatically varies in relation to the compression pressure on the piston
crown. A provisional patent recently filed by Mr. P. A. C. Brockingion, A.M.l.Mech.E., 3, Avenue Road. Stratford-on-Avon, Warwickshire, Midland representative of "The Commercial Motor," covers a design in which the rod is urged towards the position of maximum extension by the inertia of the piston, aided if necessary by a spring (not shown in the sketch), the amount of extension depending upon the relative values of inertia force and compression pressure.
The method of construction is shown
in the accompanying drawing. The top end of the rod forms a sliding fit in the lower end, in which there are a double-ended plunger. and a springloaded inertia-control piston. Lubricating oil is fed from the big end to fill the space between the working parts.
When the inertia-control piston is in it limiting upper position it closes the fluid relief passage through which fluid can flow from the top and bottom of the plunger back to the well and, in effect, lock the upper end of the connecting. rod, whether the rod is contracted or extended. This prevents rod contraction by expansion pressure and 'limits rod extension when inertia loading is exceptionally high.
When the engine piston is on the lower part of its stroke, the inertiacontrol piston is held in its tower position by inertia force aided by the spring, and relative movement of the parts is unrestrained within predetermined limits.