| 主权项 |
1. A four-stroke internal combustion engine with variable compression ratio, comprising:
a crankcase; a crankshaft being rotatable with respect to the crankcase about a crankshaft axis, wherein the crankshaft has a crankpin including a crankpin axis; a connecting rod including a big end and a small end, wherein the connecting rod has a center line which lies in a connecting rod plane; a piston being rotatably connected to the small end, wherein the piston is movable in a direction parallel to a piston plane in which the crankshaft axis lies; a crank member being rotatably mounted on the crankpin, and comprising a bearing portion which is eccentrically disposed with respect to the crankpin, wherein the bearing portion has an outer circumferential wall including a location of maximum eccentricity (P) which bears the big end of the connecting rod such that the connecting rod is rotatably mounted on the bearing portion of the crank member via the big end, wherein the bearing portion has a center line which lies in the connecting rod plane, wherein under operating conditions at or close to top dead center of the piston the angle between the connecting rod plane and the piston plane changes from a pre-angle before top dead center to a post-angle after top dead center; a drive mechanism coupled to rotate the crank member (6) with respect to the crankshaft, which is configured such that the crank member rotates in the same direction as the crankshaft, whereas a rotation frequency of the crank member is substantially half of that of the crankshaft, as seen from the crankcase; a control mechanism configured to adjust a mutual rotational position of the crank member and the crankpin at a virtual standstill of the crankshaft in order to be able to vary the compression ratio between a minimum compression ratio and a maximum compression ratio; wherein the crank member is provided with at least a crank member oil channel configured to adjust oil through the crank member to an opening in the circumferential wall of the bearing portion, wherein the opening is located outside a closed bearing range (A-B) having a first edge (A) and a second edge (B); wherein the first edge (A) is located at an intersection with the connecting rod plane where the circumferential wall faces the piston at a predetermined pre-angle in the condition of maximum compression ratio close to the end of the compression stroke; wherein the second edge (B) is located at an intersection with the connecting rod plane where the circumferential wall faces the piston at a predetermined post-angle in the condition of minimum compression ratio in the combustion stroke; wherein the closed bearing range (A-B) extends from the first edge (A) in a direction opposite to a rotational direction of the crank member with respect to the crankcase under operating condition at fixed compression ratio. |
