The invention provides a negative pressure
supercharger that can prevent the stick-slip phenomenon of the sealing lip, ensure the smooth sliding of the valve cylinder, and prevent the generation of abnormal sounds. The negative pressure
supercharger of the present invention installs a bearing sleeve (9) made of elastic material in the bearing sleeve (12) provided on the rear wall of the
supercharger housing (1), which is in contact with the supercharger
piston (5) The outer circumferential surface of the connected valve cylinder (10) is slidably supported, and a
grease storage tank (35) for holding
grease (g) is provided on the inner circumferential surface of the bearing sleeve (9). In addition, the bearing sleeve (9) The rear end of (9) is integrally connected with a sealing lip (13) whose wall thickness is thinner than the sealing lip (13) and elastically tightly connected with the outer circumferential surface of the valve cylinder (10). The inner circumferential surface of the sealing lip (13) is provided with a sealing lip (13). There is an extended
grease reservoir (35') in continuous communication with the grease reservoir (35) and holding grease (g) common to the grease reservoir (35).