GB190727361A - Improved Means for Producing Rapid Reciprocating Motion. - Google Patents

Abstract

27,361. Boys, C. V., and Tierney, J. W. Dec. 11. Compressed-air engines. -Relates to means for producing rapid reciprocating motion of a heavy body without undue vibration in cases where very little external work is required. A piston is reciprocated in an elastically held cylinder by means of an elastic-fluid spring formed by air trapped in the ends of the cylinder, means being provided to maintain reciprocation by making up energy losses. When the system vibrates, its centre of gravity remains practically at rest. Figs. 2, 3, and 4 show one method of producing and maintaining reciprocation. The cylinder c is mounted on flat springs 1 fixed to an adjustable bracket. Motive fluid is admitted from a port q, between differential piston heads m, n, and raises the piston to the grooves r. Motive fluid then flows through a passage 2 to raise the valve s and thus close the restricted exhaust ports v. More live air passes from the grooves r to the space above the piston and forces the latter downwards, compressing air in the space 3. When the pressure in the upper cylinder end falls sufficiently, the spring t forces down the valve s, and exhaust takes place. The air compressed in the space 3 arrests the downward motion and, assisted by live fluid between the piston ends, raises the piston again. The valve s closes at a definite point of the upward stroke depending on the velocity of the piston and the capacity of the passages v. At full speed the air compressed in the upper cylinder end becomes the effective means of returning the piston. Passages o, p are provided to prevent creeping, and a silencer may be provided. In a modification, the piston heads are equal, and, as the speed of the piston increases, the valve is cut out of operation, the passages v then being always closed, and exhaust taking place through the pistonrod. In a further modification, no valve is used, and the piston may be held until pressure is built up below it by live air passing through small holes in the piston. The piston is then released and starts upwards with high velocity. In all these modifications the air for making up losses of energy may be admitted to both ends of the cylinder or it may be utilized in an auxiliary cylinder. In another modification, electro-magnetic means are employed to maintain reciprocation. The Provisional Specification states that reciprocation may be maintained by means of a small alternating force, such as electro-magnetic forces, acting on the cylinder instead of being applied between the piston and cylinder directly. The frequency of vibration increases as the amplitude increases.