Patent ID: 7886710

Claim:
An oil filter unit, comprising: an oil filter; an oil cooler; and an adaptor for attaching the oil filter and the oil cooler to an attachment seating surface of a crank case having a cylinder head, wherein: the adaptor is more proximate to the crank case than the oil filter and the oil cooler; the adaptor has a first attachment surface to be attached to the attachment seating surface of the crank case and a second attachment surface to be attached to the oil cooler or the oil filter; the first attachment surface has a first closed area and a second closed area separated by a partitioning wall; the second attachment surface has an oil inlet port through which oil is introduced from an oil pump and an oil outlet port through which oil is discharged to an oil passage formed in the crank case; the oil inlet port communicates with the first closed area formed on the first attachment surface and the oil outlet port communicates with the second closed area formed on the first attachment surface; the adaptor is attached at the first attachment surface to the attachment seating surface of the crank case such that an oil supply port formed on the attachment seating surface of the crank case is positioned within the first closed area and an oil return port formed on the attachment seating surface of the crank case is positioned within the second closed area; the oil return port has a first oil return port and a second oil return port; the first oil return port communicates with a main gallery provided within the crank case via a first oil passage; the second oil return port communicates with the cylinder head via a second oil passage; and areas of the first closed area and the second closed area are larger, respectively, than areas of the oil supply port and the oil return port.