Piston cooling and/or small-end bearing lubrication arrangement for i.c.engines

Claim 1

In an internal combustion engine of the piston type and including a piston reciprocable in a cylinder, a rotary crankshaft having an oil passage therein, a crank with a crankpin formed as a part of the crankshaft, a connecting rod having a big end and a small end, a big-end bearing by which the big end of the connecting rod is journalled on the crankpin, the big-end bearing having upper and lower half-cylindrical bearing shells carried by the big end of the connecting rod, a small-end bearing by which the small end of the connecting rod is pivotally connected to the piston, a lubrication system comprising a pressurized oil supply for supplying pressurized oil to the oil passage in the crankshaft, a longitudinal oil supply passage formed lengthwise in the connecting rod and extending between its ends, a big-end oil feed passage formed in the crank and crankpin and communicating with the oil passage in the crankshaft, the big-end oil feed passage terminating in a big-end bearing lubrication hole located in the leading quadrant of the crankpin surface ahead of its top-dead-center point, an auxiliary oil supply passage formed in the crankpin and also communicating with the oil passage in the crankshaft, said auxiliary oil supply passage terminating in an auxiliary lubrication hole located in the crankpin surface in its half-side remote from the top-deadcenter point of the crankpin, said big-end bearing having an internal part-circumferential groove formed therein, the greater part of the length of the groove formed in the big-end bearing being formed in the bearing surface of the lower bearing shell remote from the piston, the auxiliary lubrication hole being in alignment with the groove so as to open into the groove during a part of each complete cycle of rotation of the crankshaft, and the groove communicating with the end of the connecting rod longitudinal oil supply passage remote from the piston, the auxiliary lubrication hole and groove being offset to one side of the big-end bearing lubrication hole in the direction of the axis of the crankpin whereby communication between the groove and the big-end bearing lubrication hole is prevented throughout the cycle of rotation of the crankshaft.