Patent GB-1473153-A (GB)
IPC: F02M31/08
Filed: 1974-07-29
Abstract: 1473153 Heating I C engine charge; manifolds HONDA GIKEN KOGYO K K 29 July 1974 [30 July 1973 5 Nov 1973] 33454/74 Heading F1 Intake and exhaust apparatus for an I.C. piston engine of the type wherein the or each cylinder has a main combustion chamber and a precombustion chamber communicating with the main combustion chamber via a flame passage, the apparatus comprising intake means including a main intake chamber and at least one main intake passageway extending from the main intake  chamber for delivering an air/fuel mixture to the or each main combustion chamber, the intake means also including an auxiliary intake chamber and at least one auxiliary intake passageway extending from the auxiliary intake chamber for delivering a richer air/fuel mixture to the or each pre-combustion chamber, exhaust means comprising a thin wall liner enveloped by and spaced within a thicker wall outer cover, the liner forming at least one passageway for collecting exhaust gases from the or each main combustion chamber and also forming an exhaust chamber connected to the exhaust passageway(s), the exhaust means having an opening and a heat conductive member forming a part of the intake means and in communication with said opening to transfer heat of the exhaust gases to the intake mixtures in the main and auxiliary intake chambers, the heat conductive member having a first portion adjacent the auxiliary intake chamber and a second portion adjacent the main intake chamber, the first portion having an effective heat conductive area of from  to <SP>2</SP>/ 3  that of the second portion. The combined intake and exhaust system is shown, Fig. 2, in an engine having pre-combustion chamber 1 communicating with each main combustion chamber 2 through a restricted flow passage 6. A main carburetter assembly supplies a lean air-fuel mixture to the main combustion chambers 2 through the manifold 17 and the auxiliary carburetter supplies a rich air-fuel mixture to the auxiliary combustion chambers 1 through the manifold 16. A main fuel intake chamber 20 and an auxiliary fuel intake chamber 32 are formed adjacent a riser member 84 covering an opening in the housing 42 of the exhaust pipe manifold 15. The housing 42 encloses a liner 44 formed of thin heat resistant material such as stainless steel. The liner 44 extends from the engine head 3 to the exhaust pipe system 56 and comprises an exhaust chamber 62 having-inlets 65 from the combustion chambers and a discharge pipe 66 leading to the exhaust pipe system 56. The liner 44 is bolted to the flange 50 surrounding the opening 48 in the housing 42, and the inlets and discharge pipe are free to expand relative to the housing. A baffle 80 is provided in the exhaust chamber to divert the exhaust gases on to the underside of the main and auxiliary intake chambers 20, 32. The height of the baffle 80 is determined empirically so as to ensure the correct amount of heating of the air/ fuel mixtures and in the present embodiment the top of the baffle is 2À5 cms below the underside of the chamber 20. Ridges 86 prevent buckling of the riser member 84 and the lateral surface area of the member associated with the auxiliary intake chamber 32 should be from  to <SP>2</SP>/ 3  of the lateral area associated with the main intake chamber 20. The vertical surface between the two lateral surfaces, in the present embodiment, is laterally spaced 3À75 to 4À0 cms from the top centre of the baffle 80. The riser surface below chamber 32 is approximately 1À5 cms below the surface under chamber 20. With a minimum thickness of  4À0 mms for the riser member 84 it is found that its temperature is in the range 160C-260C which is just suitable to vaporize the fuel. To complete combustion of the fuel the ratio of the exhaust chamber volume to the engine displacement should be within the range 0À5-0À9. The exhaust chanber volume is defined as the interior volume of the liner 44 from a vertical place tangent to the convex inner surfaces of the liner  (87), Fig. 4 (not shown) to the inlet opening 89 to the exhaust pipe 66 and the plane co-incident with the under surface of the mounting plate 68. The riser 84 is made of cast aluminium and the outer cover 42 of cast iron cast about the liner 44 after it has been covered with sand a heat shield 54 prevents conduction of heat from the exhaust to the riser and also prevents direct radiation and convection between the exhaust manifold 15 and the carburetter assemblies 12, 13.