In the course of development of pollution-reducing driving engines for motor vehicles, various systems have been proposed for operating vehicles by means of piston engines driven by compressed air. These systems usually involve the use of a source of compressed air, such as a readily rechargeable pressure tank, from which the working fluid is supplied to the engine cylinders through admission valves suitably timed to provide power strokes of the pistons, and on the return strokes the expanded air is allowed to discharge from the cylinders via suitably timed exhaust valves.
The admission of working fluid to the cylinders is usually controlled by a camshaft having individual cams acting on linkage systems operating respective air intake valves for the cylinders. In engines having groups of cylinders which are alternately acted on by the working fluid it is uneconomical to employ camshafts with individual cam elements and associated valve-operating linkage systems, and the engines of this type usually involve a large number of moving parts subject to frequent maladjustment and operational failure, are relatively cumbersome and noisy, and are inefficient in the utilization of compressed air. Also, in the case of compressed air engines of the dynamically balanced type it is desirable to employ a more reliable arrangement for synchronizing the timing of the power strokes of symmetrically arranged cylinder groups in order to maintain a proper dynamic balance.
Further background will be given by examining the following prior U.S. patents, which appear to represent the closest prior art relating to the present invention:
Jakowchuk, U.S. Pat. No. 3,190,182 PA1 Gardner et al., U.S. Pat. No. 3,618,468 PA1 Dickinson, U.S. Pat. No. 3,730,054 PA1 Murphy U.S. Pat. No. 4,018,050