Abstract: A seal retainer includes a main body and a guide wall. The main body includes a circular hole, an opposed surface opposed to the cylinder block, and a projection. The flange is arranged in the circular hole with the sealing member located between the circular hole and the flange. The projection includes a recess at a part of the projection in the circumferential direction of the circular hole. The recess extends from the distal end of the projection in an opposite direction from the cylinder block. The guide wall is arranged outward of the recess in a radial direction of the circular hole to guide air that flows in the circumferential direction of the circular hole from the radially outer side of the projection to the radially inner side of the projection through the recess.

Abstract: An oil return passage that is open at its upper end to a cam chamber and is open at its lower end to a crank chamber is formed to extend from a cylinder head to a cylinder block. A heat exchanger having a double-pipe structure is housed in the oil return passage. Lubricating oil fed from the cam chamber is passed through an oil-collection outer passage of the heat exchanger, and separated oil fed from a separator case of a PCV system is passed through an oil-collection inner passage of the heat exchanger, so that heat of the lubricating oil is imparted to the separated oil. Thus, water contained in the separated oil is evaporated, and the amount of water flowing into an oil pan can be reduced.

Abstract: There is provided an oil separator for blowby gas exhibiting excellent oil separation performance in a stable manner. In a common flow path section of a gas flow passage in which the blowby gas flows and an oil passage provided with a bottom of the common flow path section where oil that has been separated from blowby gas by separation means provided midway along the gas flow passage, the width of a part of the common flow path section is regulated so as to become gradually smaller towards the bottom of the common flow path section, and a flow passage regulating section, for making part of the common flow path section that has the width regulated a restricted section, is provided so as to extend upwards from the bottom of the common flow path section.

Abstract: An oil return passage that is open at its upper end to a cam chamber and is open at its lower end to a crank chamber is formed to extend from a cylinder head to a cylinder block. A heat exchanger having a double-pipe structure is housed in the oil return passage. Lubricating oil fed from the cam chamber is passed through an oil-collection outer passage of the heat exchanger, and separated oil fed from a separator case of a PCV system is passed through an oil-collection inner passage of the heat exchanger, so that heat of the lubricating oil is imparted to the separated oil. Thus, water contained in the separated oil is evaporated, and the amount of water flowing into an oil pan can be reduced.

Abstract: A casing of an oil separator has an inlet port through which blow-by gas flows into the oil separator, and an outlet port through which the blow-by gas flows out of the oil separator. The casing defines a blow-by gas passage the extends to connect the inlet port to the outlet port. A separation mechanism is located in the blow-by gas passage. The separation mechanism traps oil in blow-by gas, thereby separating the oil from the blow-by gas. A drain port is formed in the casing to drain the separated oil. The outlet port is located in one of opposite side portions of the casing. The drain port is located in the other one of the opposite side portions of the casing. The oil separator is capable of reliably suppressing repeated splash of the separated oil.

Abstract: There is provided an oil separator for blowby gas exhibiting excellent oil separation performance in a stable manner. In a common flow path section of a gas flow passage in which the blowby gas flows and an oil passage provided with a bottom of the common flow path section where oil that has been separated from blowby gas by separation means provided midway along the gas flow passage, the width of a part of the common flow path section is regulated so as to become gradually smaller towards the bottom of the common flow path section, and a flow passage regulating section, for making part of the common flow path section that has the width regulated a restricted section, is provided so as to extend upwards from the bottom of the common flow path section.

Abstract: A casing of an oil separator has an inlet port through which blow-by gas flows into the oil separator, and an outlet port through which the blow-by gas flows out of the oil separator. The casing defines a blow-by gas passage the extends to connect the inlet port to the outlet port. A separation mechanism is located in the blow-by gas passage. The separation mechanism traps oil in blow-by gas, thereby separating the oil from the blow-by gas. A drain port is formed in the casing to drain the separated oil. The outlet port is located in one of opposite side portions of the casing. The drain port is located in the other one of the opposite side portions of the casing. The oil separator is capable of reliably suppressing repeated splash of the separated oil.

Abstract: A collecting portion for an exhaust manifold branch where a combined pipe portion including a plurality of pipes is welded to a collecting pipe wherein, (1) an intermediate member is provided between the combined pipe portion and the collecting pipe, (2) the collecting pipe has a portion that extends upstream, (3) a weld line formed at the downstream end of a partitioning wall is axially zigzagged, (4) a weld line is offset from the downstream surface of the combined pipe portion, (5) only one of the partitioning walls is curved, (6) downstream ends of the partitioning walls are smoothly convex, (7) an additional weld is formed in the partitioning wall, or (8) an intermediate member is welded at a half circumference of the combined pipe portion.