GB585391A - Improvements in and relating to internal combustion engines - Google Patents

Abstract

585,391. Two-stroke engines. WEIGED D. M. Oct. 13, 1943. No. 16821. Convention date, March 16, 1942. [Classes 7 (ii) and 7 (vi)] A two-stroke internal-combustion engine particularly an engine of the kind described in Specification 543,359 has a combustible mixture produced by injecting fuel into air which has been compressed and then cooled below the temperature of spontaneous ignition the air or mixture being introduced into a combustion chamber separate from the working cylinder by a mechanically operated valve during the exhaust stroke of the engine. An air cooled cylinder 10 carries a slidable sleeve 14 reciprocated by positively-acting cams 16, 17 mounted on the crankshaft 12. The head 23 is bolted to the upper part of the cylinder and packing rings are provided at 24. The head is fitted with an exhaust valve 43 actuated from a cam 41 on the crankshaft through a tappet 42 and push rod 44. The piston 26 reciprocating in sleeve 14 has a rod 27 secured to a cross-head 28 slidable in an extension 29 of the lower cylinder cover 30 which is bolted to the cylinder at 34. A connecting rod 33 connects the cross-head to the crankshaft. The lower end of sleeve 14 has an intake port 51 which during the upper part of the sleeve travel, corresponding, with the upward movement of piston 26, registers with an air intake 52 so that air is drawn into the space beneath the piston. On the downward stroke, a port 55 in the sleeve registers with a port 56 leading to an intercooler 57 so that the air drawn in through intake 52 is compressed and transferred to the intercooler. The outlet header 60 of the intercooler communicates with a passage 62 coacting with a port 64 to transfer the cooled compressed air to a combustion chamber 61, where the air is mixed with an injected fuel charge this transfer occurring during the middle part of the upward piston movement. Towards the end of this movement a port 66 opens the combustion chamber to the cylinder and the charge is fired by a spark-plug 68. The exhaust valve 43 is opened near the bottom of the working stroke and continues. open until shortly before the opening of the port 66. The fuel. pump may be of variable stroke piston type, Fig. 3, the delivery being varied in response to variations in the air charge by means of a pipe by which the intercooler pressure is applied to a bellows controlling a rod which through a servomotor, rod 90 and linkage 92, 94 is connected to a member 75 supporting the piston 72 of the fuel pump cylinder 71 from which fuel is delivered through pipe 78 to the combustion chamber. The pump is driven from the crankshaft and a projection 85 actuates the pump piston the stroke of which is thus varied in accordance with position of member 75. Thus in operation the underside of the piston 26 serves to pump air into the intercooler, the air charge per stroke depending on the setting of the throttle. When equilibrium is reached, the same charge passes into the combustion chamber during each upstroke of the piston where it is mixed with the fuel before the combustion chamber is opened to the cylinder, at which point the charge is ignited by the plug 68. The cooling of the air in the intercooler removes the heat of compression and enables high compression ratios to be used without risk of pre-ignition. Instead of supplying the fuel to the combustion chamber, it may, as shown in Fig. 1 be supplied at the discharge end of the intercooler at a time when the intercooler is open to the combustion chamber. Other forms of fuel supply control may be used. Specifications 388,735, 478,422 and 478,471 and U.S.A. Specification 2,303,966 also are referred to.