INTERNAL COMBUSTION ENGINE

To reduce friction at a change of a compression ratio immediately after warmup.SOLUTION: A housing 28 has a first space 61 in which a reduction gear 35 is accommodated, a second space 62 penetrated with a second control shaft 24, and a bulkhead 63 located between the first space 61 and the second space 62, and partitioning both the spaces. A first discharge hole 67 and a second discharge hole 68 for discharging a lubricant in the first space 61 to the second space 62 are formed at the bulkhead 63 so as to penetrate it. The first discharge hole 67 is located at a lower part lower than the second discharge hole 68, and formed so as to be increased in passage resistance more than that of the second discharge hole 68. An internal combustion engine supplies a larger quantity of the lubricant larger than that immediately after a start to the first space 61 during warmup for holding a compression ratio at a prescribed intermediate compression ratio. The internal combustion engine adjusts a height of an oil level in the first space 61 by the first discharge hole 67 immediately after the start, and adjusts the height by the second discharge hole 68 during the warmup.SELECTED DRAWING: Figure 3 【課題】暖機直後の圧縮比変更時のフリクションを低減する。【解決手段】ハウジング２８は、減速機３５が収容される第１空間６１と、第２制御軸２４が貫通する第２空間６２と、第１空間６１と第２空間６２との間に位置して両者を隔てる隔壁６３と、を有している。隔壁６３には、第１空間６１内の潤滑油を第２空間６２へ排出する第１排出孔６７及び第２排出孔６８が貫通形成されている。第１排出孔６７は、第２排出孔６８よりも下方に位置し、第２排出孔６８よりも通路抵抗が大きくなるよう形成されている。内燃機関は、圧縮比を所定の中間圧縮比に保持する暖機中、始動直後よりも多くの潤滑油を第１空間６１に供給する。内燃機関は、第１空間６１内の潤滑油の油面高さを始動直後は第１排出孔６７で調整し、暖機中は第２排出孔６８で調整する。【選択図】図３