| 摘要 |
In a vehicle with an automatic transmission (4), an internal combustion engine (1) is provided with a variable compression ratio mechanism. A target compression ratio tCR of the variable compression ratio mechanism is determined with reference to a compression ratio map in which the target compression ratio value has previously been defined using a demand load tT and an engine rotation speed Ne as parameters. A reverse-drive compression ratio map is selected when the automatic transmission is in a reverse drive position; a first compression ratio map is selected when an actual speed reduction ratio RR of the transmission is low; and a second compression ratio map is selected when the actual speed reduction ratio RR of the transmission is low (S3 to S7). A variable control range of the compression ratio is narrower in the second compression ratio map for the high speed reduction ratio than in the first compression ratio map and is narrower in the reverse-drive compression ratio map than in the first and second compression ratio maps. By this compression ratio control, it is possible to suppress the occurrence of an unintended torque change due to changes of compression ratio when the speed reduction ratio is high. |
