LUBRICATING DEVICE FOR SUPERCHARGER OF INTERNAL COMBUSTION ENGINE

PURPOSE:To prevent abnormal rising of oil level by forming an air inlet port through a counterflow preventing device at the place where negative pressure is generated as synchronous gears rotate, in a gear casing which houses synchronous gears provided on rotor shafts of a pair of rotors of a supercharger. CONSTITUTION:A gear casing 25 is fixed outside the side housing 24 of a supercharger 10 driven by an engine and synchronous gears 26 fixed to the ends of respective rotor shafts 21 are housed in a state of meshing with each other. And bearings 23 and oil seals 30 which support rotor shafts 21 freely rotatably are lubricated by a forced lubrication system 31 which supplies pressurized lubricating oil 28 to an oil supplying passage 32 in the side housing 24 via a going passage 31a. On this occasion, an air inlet port 35 is provided on the gear casing 25 at the place where negative pressure is generated. In addition, a check valve (not shown on the drawing) which permits only air inlet to the gear casing 25 from the outside is provided on this air inlet port 35.