Control device and control method for variable compression ratio internal combustion engines

摘要

There are provided a variable compression-ratio mechanism (20) capable of varying an engine compression ratio in accordance with a rotational position of a control shaft (24); a speed reducer (44) configured to reduce in speed a rotational power of an actuator and transmit the speed-reduced rotational power to the control shaft (24); and a speed-reducer accommodating case (43) accommodating the speed reducer (44). An input shaft of the speed reducer (44) which is connected to the actuator has a shaft center line extending along a horizontal direction, and at least a part of the input shaft is kept under a lubricating oil retained in the speed-reducer accommodating case (43). The input shaft of the speed reducer (44) is swung by a predetermined swing angle to avoid inadequate lubrication of the input shaft of the speed reducer (44), during an operating state where the engine compression ratio is maintained constant.

主权项

1. A control device for a variable-compression-ratio internal combustion engine, the control device comprising:
a variable compression-ratio mechanism including a control shaft and link connected to a crankshaft of the internal combustion engine, the variable compression-ratio mechanism being configured to vary a compression ratio of the internal combustion engine in accordance with a rotational position of the control shaft; an actuator configured to drive the control shaft; a speed reducer provided between the actuator and the control shaft and configured to reduce in speed a rotational power of the actuator and transmit the speed-reduced rotational power to the control shaft; and a speed-reducer accommodating case accommodating the speed reducer, wherein an input shaft of the speed reducer which is connected to the actuator has a shaft center line extending along a horizontal direction, at least a part of the input shaft is kept under a lubricating oil retained in the speed-reducer accommodating case, and the control device further comprises a control section configured to swing the input shaft of the speed reducer by a predetermined swing angle during a predetermined operating state where the compression ratio of the internal combustion engine is maintained constant.