| 摘要 |
A scroll vacuum pump (1) includes a first stage having a first stage fixed plate (3) with a spiral involute (5), a second stage having a second stage fixed plate (17) with a spiral involute wrap (15), and an orbiting plate (7) having upper and lower surfaces. An involute spiral (19) extends from the orbiting plate bottom surface to define a first stage orbiting plate and a second involute spiral (13) extends from the orbiting plate top surface to define a second stage orbiting plate. The first stage involute wraps are taller than the second stage involute wraps. Gas is expanded in the first stage and compressed in the second stage. The first stage has an expansion ratio greater than or equal to one and the second stage has a compression ratio greater than or equal to one. However, that the pressure at the second stage exit is less than the pressure at the first stage inlet. To increase the efficiency of the pump, the tip seals (54) of the involute spirals are extended as close as possible to the center of the involute to delay porting of gas by 180 DEG of rotation.
|
