| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent the breakage of a vane by the reverse rotation of a vacuum pump, in a vane type vacuum pump suitably used for a vacuum booster for motor vehicle, by providing a pressure reducing means in a displacement chamber which is abnormally raised in pressure when the vacuum pump is reversely rotated. SOLUTION: When an engine is operated to rotate a rotor 3 through a rotating shaft 1, displacement chambers 11a-11c are changed in volume according to the rotation of the rotor 3, and the air sucked through an intake port 6 and lubricating oil are discharged through a discharge port 9. In this case, a pressure rising preventing groove 12 for storing or releasing the lubricating oil or air is formed on the casing 5 or plate 8 located in a space (chamber) 11a formed between the minimum clearance part between the inside surface of the casing 5 and the outside surface of the rotor 3 and the intake port 6 located in the position of about the angle of 360 deg./the number of vanes in the normal rotating direction on the basis of the minimum clearance part. According to this, pressure rising within the space 1a in the reverse rotation of the vacuum pump can be reduced to prevent the breakage of the vanes.
|
