Patent GB-704743-A (GB)
Title: Improvements in or relating to reciprocating piston engine type gas generators for gas turbines
IPC: F02B75/10
Filed: 1948-02-11
Abstract: 704,743. Internal-combustion engine gas generators. BUCHI, A. Feb. 11, 1948, No. 3988/48. Classes 7(1), 7(2) and 7(6) A four stroke internal-combustion engine generating gas for actuating a turbine comprises a pump for delivering charging air for the intake period of the engine and at least one pump for delivering secondary air which is of a higher pressure than that of the charging air and is used for cooling the exhaust gases and scavenging the cylinders of the engine, the latter being supplied with said charging and secondary air through the same controlling devices. As shown, the engine operates with a cross head 4<1> which acts as the piston 5<1> of the charging air pump. The piston 5<1> is connected to the working piston 2<1> which drives the secondary air pump through the crankshaft 6. The piston 5<1> may comprise a double acting differential piston wherein the lower piston guide serves as a cross head. Each cylinder 1<1> has at least one set of inlet and exhaust valves 10, 11, respectively which are actuated by a camshaft 12, cams 13, 13<1> and control gear 14. The charging air is drawn through suction valves 17<1> and fed to a receiver 19 whilst the secondary air is fed to a space 22. At least one piston type sleeve valve 21 is associated with each cylinder to control the supply of charging and secondary air thereto. The valve 21 is operated by the camshaft 12 through gearing 27, 28 and comprises a guide 23, a stationary guide 24 and piston rings 25, 26. The stationary guide 24 extends into the members 21, 23 to define therewith a space which communicates with the atmosphere. The inner diameter of the guide 23 is so chosen and sealed against the space 22 that the piston sleeve is subjected to approximately equal forces above and below. The engine cylinders 1<1>, the cylinder covers 20<1> and the charging air pump cylinders 15<1> may be water or air cooled. In a modification, Fig. 2 (not shown), the internal combustion engine comprises two crankshafts and two cylinder banks which have a common receiver 19 disposed therebetween. A single sleeve valve is provided between each opposed pair of cylinders, the pistons of which may have simultaneous work phases. The crankshafts may be contra rotating: and coupled through suitable gearing which drives the engine auxiliaries such as water pumps, electrical generators and fans. The charging air pumps may serve as the first stage of the secondary air pump which is supplied through an opening 31 in the receiver 19. In a second modification, Fig. 3 (not shown), two sleeve valves are provided to serve each pair of opposed cylinders. In a further modification. Fig. 4 (not shown), applied to a twinbank gas generator having two banks of eight cylinders each with separate crankshafts for each bank, the secondary air pump is driven by the crankshaft of at least one engine cylinder bank. Moreover, each cylinder has duel inlet valves and dual exhaust valves. The Specification as open to inspection under Sect. 91 comprises also the subject-- matter of Specifications 704,771, and 704,772. This subject-matter does not appear in the Specification as accepted.