A method and plant for the start-up of a pressure charged diesel engine that has a low compression ratio.

摘要

1482605 Heating IC engines and combustion air SOC D'ETUDES DE MACHINES THERMIQUES 29 July 1974 [16 Oct 1973 28 Dec 1973] 33369/74 Heading F1B A method of heating the air supply to one or more cylinders of a low compression ratio I.C. engine during starting thereof, the engine having an exhaust gas driven supercharger, comprising the steps of operating the engine so that only comression of the air drawn in takes place, while operating control means to impede the flow of exhaust gases from the cylinder(s) so that a controlled residual amount of working gases heated by compression is retained in the cylinder(s) to pre-heat the air subsequently entering, and operating said control means to provide flow of the exhaust gases unimpeded by the control means as soon as the engine has started. Compression-ignition engine 1 has an intake manifold 3 and an exhaust manifold 5 connected to individual cylinders 2 by branch pipes 6. The exhaust gas drives the turbine 7b of a high-pressure blower 7a and the turbine 8b of a lowpressure blower 8a. Between the blowers is an inter-stage cooler 17 and downstream of H.P. blower 7a is a cooler 23. Combustion air which enters cylinders 2 is heated by mixing with residual exhaust gas and the degree of heating is increased by restricting the outflow of exhaust gases so that a greater quantity of exhaust gases remains in the cylinders. Exhaust gas flow is restricted by a butterfly valve 48 or sliding damper at the outlet 10 of turbine 7b, or upstream of turbine 7a, or anywhere in duct 11, or at the outlet 13 of turbine 8b. In Fig. 2 (not shown) the exhaust gas control member (51) is at the downstream end of exhaust manifold 5 or a control member may be interposed in each branch pipe 6. The combustion air may also be pre-heated by (a) Passing a hot fluid, instead of a cold fluid, through cooler 23. This is effected by changeover valves 34, 35. (b) Mounting a fuel burner 37 on intake manifold 3 and injecting hot combustion gases directly into the manifold. (c) Passing a hot fluid instead of a cold fluid through the liquid coolant circuit of the engine. This is effected by changeover valves 43, 44. (d) Enclosing the engine and heating the enclosure. The air pre-heating may be controlled through servo-control means in accordance with the instantaneous operating conditions of the engine, to vary the air temperature in inverse proportion to the load or rotational speed of the engine or the pressure of the air.