| 摘要 |
PURPOSE:To smoothly return the lubricating oil of an overhead-cam-type internal combustion engine, by utilizing the vacuum pump of a vacuum-type brake booster so that the lubricating oil gathering in the top chamber of a cylinder head is forcedly returned to an oil pan. CONSTITUTION:When a brake pedal 20 is not pressed down, an oil passage 27 extending from an oil drain port 26 in a cylinder head 3 is connected to a vacuum pump 19 through a three-way valve 30 so that lubricating oil gathering in the top chamber of the cylinder head 3 is suched out together with a small amount of blow- by gas through the port 26 and the passage 27 by the vacuum pump 19 and then returned to an oil pan 5 through a drain passage 25. More than a prescribed quantity of the lubricating oil is thus prevented from staying in the top chamber 9. When the brake pedal 20 is pressed down for braking, a switch 33 is closed to shift the three-way valve 30 to apply negative pressure to a brake booster 21 so that prescribed braking action is caused. |
