Variable compression ratio apparatus for internal combustion engine

A variable compression ratio apparatus for an internal combustion engine having at least one cylinder, a piston reciprocally disposed within the cylinder and a connecting rod pivotally connected at one end thereof to the piston and at the other end thereof to a crankshaft, comprising:

• an eccentric sleeve rotatably arranged in a pivot portion at the other end of the connecting rod so as to make a bearing hole of the connecting rod and the crankshaft, which extends through the bearing hole, eccentric relative to each other;
• and
• an eccentric sleeve lock means capable of fixing rotation of the eccentric sleeve at a desired position, said eccentric sleeve lock means comprising:
• a pair of flange portions formed to flank the connecting rod at opposite ends of the eccentric sleeve,
• a pin member provided inside the connecting rod such that the pin member is allowed to project toward one of the flange portions,
• a first engagement portion provided on one of the flange portions and engageable with the pin member when the pin member projects out toward said one of the flange portions,
• a second engagement portion provided on the other flange portion and engageable with the pin member when the pin member projects out toward the other flange portion, and
• a piston-type fluid pressure drive system having a means for producing a pressure difference between fluid pressure chambers formed at opposite sides of a piston portion, which is connected to the pin member, in a state that the fluid pressure chambers are applied with a prescribed fluid pressure, whereby the piston portion is moved along an axis of the eccentric sleeve to drive the pin member such that the pin member is allowed to project out from the connecting rod toward one of the flange portions.

A variable compression ratio apparatus for an internal combustion engine having at least one cylinder, a piston reciprocally disposed within the cylinder and a connecting rod pivotally connected at one end thereof to the piston and at the other end thereof to a crankshaft, comprising:

• an eccentric sleeve rotatably arranged in a pivot portion at said one end of the connecting rod so as to make a bearing hole of the connecting rod and a piston pin, which extends through the bearing hole, eccentric relative to each other;
• and
• an eccentric sleeve lock means capable of fixing rotation of the eccentric sleeve at a desired position, said eccentric sleeve lock means comprising:
• a pin member provided inside the connecting rod movably from the inside of the connecting rod in a direction at an angle to the longitudinal axis of the eccentric sleeve such that the pin member is allowed to project out toward the eccentric sleeve,
• first and second engagement portions formed on the eccentric sleeve with a desired angular interval therebetween, one of said first and second engagement portions being engageable with the pin member when the pin member projects out toward the eccentric sleeve;
• and
• a piston-type fluid pressure drive system having a means for producing a pressure difference between fluid pressure chambers formed at opposite sides of a piston portion, which is connected to the pin member, in a state that the fluid pressure chambers are simultaneously applied with a prescribed fluid pressure, whereby the piston portion is moved to drive the pin member such that the pin member is allowed to project out from the inside of the connecting rod toward the eccentric sleeve.