| 摘要 |
PROBLEM TO BE SOLVED: To avoid holding inability caused by resonance of a cogging brake, by holding a position of a control shaft for regulating a compression ratio by using the cogging brake. SOLUTION: In a constitution having a double-link type variable compression ratio mechanism for changing the compression ratio by a rotational position of the control shaft, since combustion pressure and torque by inertia act on an electric motor for controlling the control shaft, a cogging brake for generating cogging torque by current-carrying is arranged in parallel to the electric motor, to hold the position of the control shaft at the OFF-time of the electric motor. A resonance frequency of the cogging brake is determined based on target holding torque (Step 2), and when this resonance frequency approaches an engine oscillation frequency, the target compression ratio is set to the low compression ratio (Step 3 and 7). Load torque acting on the cogging brake from the control shaft side reduces by reduction in the compression ratio, enabling holding. COPYRIGHT: (C)2011,JPO&INPIT
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