Patent GB-731889-A (GB)
Title: Means for improving the combustion efficency of reciprocating internal combustion engines
IPC: F02B51/02
Filed: 1953-06-19
Abstract: 731,889. Catalytic mixture-oxidizing elements. HOUDRY, E. J. June 19, 1953, No. 17017/53. Class 7(2). Construction. In an engine having in the combustion chamber of each cylinder a sparking plug and at least one element 21, Fig. 3, providing a surface of oxidizing catalyst sufficient in area to retard premature detonation, the element 21 being composed of ceramic material and having a coating of catalytic material on the lower end thereof, the element is carried by a plug 17 inserted into an auxiliary opening in the cylinder head so that the plug may be readily removed to permit replacement of the catalyst surface without replacing the entire plug and element assembly. The active surface of each plug 17 is flush with the adjacent combustion chamber wall. Three diverging catalytic elements 21 are provided each of which protrude from the surface 20 of the plug and are secured thereto in wedge-shaped grooves, the elements being either made from, coated with or have catalytic members mounted thereon ; the elements 21 are fired at a temperature of 2500-2900‹F. and then coated with a base film of active alumina, magnesia, beryllia, or thoria which is subsequently impregnated with an oxydizing catalyst such as platinum, silver or copper. In a modification two of the three elements are of equal length and perpendicularly arranged upon the transversely disposed third element. The plug is screwed into the cylinder head with the central or two parallel elements positioned radially of the cylinder. In another modification, the plug is in the form of a sleeve 27, Fig. 7, and has a core 29 of catalytic material extending beyond the casing, which core is retained in position by a shoulder 28 and a screw piece 33, an asbestos or similar insulating washer 32 being interposed between the core 29 and piece 33 whilst gaskets 31 are located.between the shoulder and the core 29. The active surface of the core is grooved and a number of rods 34 arranged in parallel or grid formation are housed in the grooves and fixed to the casing, which rods serve to evenly distribute the heat across the core and to prevent pieces of the latter falling into the combustion space. In a further modification between three and six plugs of the same general construction as in Fig. 7 above are arranged around the periphery of each cylinder ; the cylinder head wall in the vicinity of the plug nearest the sparking device is modified as shown by the lines 60, 61, Fig. 10, to permit the medium in the cylinder to have access to the projecting end 50a of the catalytic core 50, and to provide a sufficient depth of metal for mounting the plug. The amount of protrusion of the catalyst into the combustion chamber is adjustable. Operation. When the engine has reached normal operating temperature the incoming combustible mixture contacts the catalytic plugs and flameless oxidation occurs and continues throughout the compression strokes up to and beyond the moment of spark ignition for as long as any unoxidised fuel is in contact with the plugs ; knocking is thereby avoided, even when low octane fuels are used. Between 0À4 and 0À16 square inch of catalyst surface per cubic inch of piston displacement provides for the necessary fuel oxidation. The use of a catalyst provides a similar effect to that obtained by increasing the engine compression ratio.