| 摘要 |
PROBLEM TO BE SOLVED: To rationally configure a vacuum pump for inhibiting the intake of outside air into a drive chamber when a piston is actuated in the air exhaust direction.SOLUTION: A vacuum pump includes a piston 2 that partitions a cylinder 1 into a negative pressure chamber A on the cylinder head 41 side and a drive chamber B on the opposite side of the negative pressure chamber A, and a valve unit V that is disposed on the cylinder head 41 and allows only supply of a fluid to the negative pressure chamber A when the piston 2 is actuated in the air intake direction. The vacuum pump further includes a valve device D having a piston ring 30 which is inserted into an annular groove 2G of the piston 2 and is narrower than the annular groove 2G, and having a communication hole 2T through which the annular groove 2G communicates with the outer space via the drive chamber B, the valve device blocking communication between the communication hole 2T and the negative pressure chamber A as the piston ring 30 moves with operation in the air intake direction and making the communication hole 2T communicate with the negative pressure chamber A as the piston ring 30 moves with operation in the air exhaust direction. |
