GB190816685A - Improvements in Valveless Engines, the Invention being applicable also to Percussive Machines such as Rock Drills. - Google Patents

Abstract

16,685. Mauss, W. Aug. 8. Rock drills.-In valveless rock drills, the piston is driven, during the forward stroke, partly by jets of fluid which pass through piston-controlled grooves in the cylinder and impinge upon a suitable surface attached to the piston. The resulting pressure formed in the forward end of the cylinder reverses the piston. Fluid-pressure is admitted to the drill shown in Fig. 1 through ports d, and acts continuously upon the annular surface e of the piston b. Towards the end of the forward stroke, the fluid passes through ports h, the forward ends of which are tapered, and impinges upon the surface k<1> of a collar k attached to the piston-rod. The pistonrod is hollow, communicates with the atmosphere, and contains exhaust ports m, m<1>, which are opened on the return of the piston. The port m, of restricted area, maintains the exhaust for a portion of the forward stroke and thereby minimizes compression of fluid in the front part of the cylinder. A series of exhaust ports of increasing size or a tapered slot may be provided. During excessive forward movement of the piston, the collar k enters a cushioning-recess l<1>, which at the end of the stroke is exhausted through passages p, n and a port o to the atmosphere. In a modification of the drill, the piston b and the collar k are provided with protruding edges to increase the effectiveness of the jets.