GB675984A - Improvements in and relating to means for automatically varying the volumetric capacity of combustion chambers for internal combustion engines and compression ignition engines - Google Patents

Abstract

675,984. Cylinders. HUMPHREYS, I. B. Oct. 11, 1949 [May 11, 1949], No. 26074/49. Class 7(ii) In apparatus for automatically varying independently the volumetric capacity of each combustion chamber of an internalcombustion engine to maintain the pressure in the chamber below a predetermined degree irrespective of the load conditions, comprising a movable element such as a piston D, forming part of the chamber wall and arranged with its outer face in contact with a body of liquid, for example, oil, confined within a compartment E, which has an outlet normally closed by a valve 17 mechanically independent of the piston D and loaded so that when the pressure in the chamber reaches the predetermined degree the valve will automatically open and permit the liquid to escape substantially freely without opposition from the compartment E and allow the piston D to be moved by the pressure in the chamber away from its normal position forming part of the chamber wall, the compartment E is provided with a liquid supply, through a conduit 15 for example, so that the cylinder is kept full of liquid and when the chamber pressure falls below the predetermined degree the piston D will be moved by the liquid towards its normal position forming part of the chamber wall. The engine cylinder head 2 has an opening 3 that communicates with a cylinder 4 attached to, or integral with, the head, the cylinder 4 housing the stepped piston D the enlarged part 7 of which is contained in but spaced from the walls of the compartment E that is a con-. tinuation of cylinder 4. An orifice in the head of the compartment E is closed by the ball valve 17 which is adjustably spring- loaded; when the valve 17 is lifted it places the compartment E into communication with a receptacle F that is open at the bottom through a conduit 20 to the engine crankcase or other liquid reservoir The cylinder 4 has a connection 13 with the engine crankcase to provide an outlet for any gases escaping past piston D whilst the compartment E is supplied with oil or similar liquid from the engine lubricating pump or a separate pump through conduit 15. The piston D incorporates a flange 9 which when in contact with a flange 10 on the cylinder 4 defines the innermost position of the piston. In a modification, the ball valve is replaced by a poppet-type valve and the piston flange is dispensed with, the enlarged part of the head being arranged to abut a flange on the cylinder in order to define the inner position of the control piston, which latter feature, in conjunction with an additional stepped part on the piston head ensures a more satisfactory dashpot action of the piston, which latter may be replaced by a diaphragm.