GB962628A - Improvements in or relating to turbocharged internal combustion engines - Google Patents

Abstract

962,628. Charging engines; motor power plant. BRITISH INTERNAL COMBUSTION ENGINE RESEARCH ASSOCIATION. Aug. 2, 1961 [Aug. 11, 1960(2)], Nos. 27807/60 and 27808/60. Headings F1B and F1Q. In an I.C. engine pressure charged by a compressor driven by a turbine actuated by the exhaust gases of the engine, positively controlled and metered volumes of air are passed from the compressor to the turbine without passing through the engine. Some of the air passing from a charging compressor 4, Fig. 1, driven by an exhaust gas turbine 3, is by-passed to a metering device 2 to be passed into the exhaust gases of an engine 1 at any convenient position such as 7 or, adjacent the exhaust valves through jets which direct the air onto the backs of the heads of the valves for cooling purposes. The remainder of the compressed air is fed to the engine 1 through a cooler 6 which, if the engine is of the spark ignition type, is replaced by a carburetter. The device 2 is a positive displacement compressing and expanding machine, for example, a Roots, lobe or sliding vane compressor or blower, and absorbs engine power when its outlet pressure is higher than its inlet pressure and returns power to the engine when the reverse is the case. The weight of air by-passed is approximately proportional to the weight of air trapped in the cylinder so that the ratio of fuel to total air supplied does not vary appreciably with engine speed. The metering device may be free running and dependent on the inertia of its parts to ensure approximation to the desired characteristics. The volume of air by-passed may be varied other than by the speed of the engine by providing a drive independent of the engine, or by providing a metering machine in which the throughput is variable, such as the rotary machine described in Specification 665,484. In Fig. 4, pulleys 27 and 28 may be of the variable speed type or driving means independent of the engine may be mounted in position of pulley 27 or 29. The by-passed air is fed through conduit 22 and metering device 2 to conduit 23 to encircle and cool the exhaust manifold 24 after which the air unites with the exhaust at 25 and is fed through the turbine of the turbocharger 16. The remainder of the compressed air is passed through a cooler 20 to inlet manifold 21. The by-passed air may be fed directly to a separate segment of the turbine nozzle ring so that in two-stroke engines and when a positive displacement metering device is engine or separately driven, this arrangement, on starting the engine, ensures that the turbine is set spinning to provide air for combustion. In Fig. 7 air, compressed in charge compressor 53 driven by an exhaust-gas turbine 50, is passed along conduit 55 to junction 56. One portion of the air is led by conduit 57 through a cooler 58 to the inlet 45 of a cylinder 41. The other portion passes along conduit 59 through heat exchanger 52, which receives its heat from the exhaust gases passing along conduit 51, to do work on the underside of the piston 42 connected to a crosshead 67. Control valve 69 allows passage of air into the cylinder 41 during the upstrokes of the piston, and valve 71 opens at or near T.D.C. to allow the air to expand to the atmosphere. Conduit 72, leads a portion of the air to a metering device 61 driven by the crankshaft 44 by way of intermediate shaft 83. The metering device 61 allows a measured quantity of air to be passed by the conduit 62 into the exhaust conduit 49 leading to the turbine 50. The crosshead and the provision for feeding air to the underside of the piston may be omitted, and some of the air from the conduit 62 may be fed to an additional turbine or other expansion machine which may drive another machine or be coupled to the engine crankshaft. The cooler 58 may be omitted. In Fig. 8, one portion of the air from compressor 53 passes to cooler 58 and then to the inlet manifold 73. A further portion of the air passes through conduit 59, heat exchanger 52 and conduit 60, and then branches at 63, part going to a turbine 65 which may drive an additional machine or may be connected by reduction gearing 77 and hydraulic coupling 78 to crankshaft 44 to thereby supply additional power to the latter. The remainder of the air passes along conduit 74 through a metering device 61 to the exhaust conduit 49 leading to turbine 50. The metering device 61, is adjustable in accordance with engine load and speed as by the combined effect of a rack controlled rod 79 of the fuel injection pump 80 and a governor 81, through linkage 82. Exhaust gases of the engine and exhaust air from the turbine 65 unite at 75 and pass to atmosphere.