Patent GB-723711-A (GB)
Title: Improvements in the inlet passages of four-stroke internal-combustion engines
IPC: F02F1/24
Filed: 1952-10-16
Abstract: 723,711. Four-stroke engines. TEXACO DEVELOPMENT CORPORATION. Oct. 16, 1952 [Nov. 27, 1951], No. 25962/52. Classes 7 (2) and 7 (3). In a four-stroke engine having a cylinder 10, Fig. 2, with an air intake 15 and inlet valve 16 constructed to provide induction air swirl in the cylinder, fuel injection means, such as a nozzle 21 and a pump for injecting fuel into a localised portion of the swirling air, means for example a sparking plug 24, for establishing a flame front 60, the fuel injection means continuing the injection in each cycle immediately in advance of the flame front 60 to progressively form additional increments of combustible mixture which are ignited by the flame front and burned as rapidly as formed, the intake 15 has a cross-section that changes progressively in the flow direction and is devoid of sharp bends and protuberances, the minimum area of flow passage at the maximum valve lift being at the valve seat the intake portion upstream of the seat having a flow axis that makes an acute angle to a plane normal to the axis of the swirling air in the cylinder 10 and which opens into the latter in the direction of the air swirl. The fuel pump which is driven from the camshaft at half engine-speed draws fuel from a tank and supplies it to the nozzle 21 through a check valve at a pressure of 500-3000 p.s.i. The cylinder head incorporates the valve 16 which has a 120 degree-180 degree shroud 17, an exhaust port, not shown, controlled by a valve 19, and the tangentially arranged injection nozzle 21, the conical spray from which travels in the direction of the air swirl shown by arrow 23 whilst the sparking plug 24 is mounted less than 90 degrees downstream of the nozzle. From the boss 37, Fig. 3, to the line 38 the intake 15 is of circular cross-section ; beyond the line 38 the section changes due to a rise 39 Fig. 4, in the lower wall and outward flaring of the side walls 40, 41, Fig. 3, to an elliptical cross-section adjacent the valve seat. The upper wall curves downwardly at 42, Fig. 4, and merges into a straight surface 43 leading into an upstanding portion 45 which houses the valve guide 46 ; beyond portion 45 the top wall sweeps downwardly at 48 to bring the edge of the valve seat in line with surface 43. The lower wall of the port beyond rise 39 merges into the opposite side of the valve seat whilst the side walls gradually curve inwardly at 52 and 53, Fig. 3, to define an elliptical crosssection perpendicular to the direction of air flow 44, Fig. 4, above the valve seat. The centre of the valve seat is at a radius from the cylinder axis of 0À4-0À6 of the cylinder radius with the outer edge of the seat close to the cylinder periphery ; the Mach number of the port and valve is 1À0 at an average piston speed in excess of 3,500 feet per minute. The average flow coefficient of the intake and valve is determined by placing the latter in series with a standard orifice whilst the average swirl efficiency is determined by an aneometer; correlating formula for these factors are given. The shroud 17 faces the incoming air and with the valve fully open the upper shroud edge 56 is in line with the top of the valve seat at this point. The engine operates on the Otto cycle and has a compression ratio of 8-12 : 1. Ignition may be effected by a glow plug or chemical or catalytic means and the poppet inlet valve replaced by sleeve valves for example. Specification 596,846 is referred to.