| 摘要 |
PROBLEM TO BE SOLVED: To prevent inferior lubrication of a high pressure fuel pump caused by lowering of the viscosity when the temperature of the fuel is excessively increased. SOLUTION: If the temperature of fuel in a high pressure fuel pump estimated (S2) from a temperature of fuel in a fuel tank exceeds an upper limit value T1 (S5), in general, a high fuel temperature pressure map (S5) is used, instead of a normal fuel pressure map (S4) so as to lower a desired fuel pressure. In order to avoid unstability of combustion, the combustion is forcibly changed over into homogenous combustion (S8) if the combustion is in a stratified combustion range (S7). Sine the surface pressure exerted to a slid part in the fuel pump is lowered, an effective oil film thickness can be ensured, thereby it is possible to enhance the lubricity and to reduce the friction.
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