Vacuum generating system

Claim 2

A vacuum evacuation system comprising: a first vacuum pump having a rotary component and a suction port and an exhaust port, in which gas molecules are caused to collide with said rotary com­ponent rotating at high speed so as to be given a momentum in a direction of linear velocity of said rotary component so that a gas flow is produced in a given direction; a second vacuum pump including a casing pro­vided with a suction port and an exhaust port and a pair of male and female screw rotors supported within said casing with a slight gap maintained between said casing and said screw rotors, said pair of male and female screw rotors being rotated with a slight gap maintained therebetween to produce a differential pressure between said suction and exhaust ports provided in said casing; piping means for connecting said exhaust port of said first vacuum pump to said suction port of said second vacuum pump; and said suction port of said first vacuum pump being disposed on a vacuum side, and said exhaust port of said second vacuum pump being disposed on an atmospheric side.

Claim 3

A vacuum evacuation system as defined in claim 1, wherein said first vacuum pump comprises an outer case, a rotary shaft disposed within said outer case and supported rotatably, a plurality of rotor blades fixedly mounted on said rotary shaft, and a rotor fixedly mounted on said rotary shaft and having an outer peripheral surface formed with a helical groove.

Claim 4

A vacuum evacuation system as defined in claim 1, wherein said first vacuum pump comprises a stationary outer case, a motor disposed within said outer case and having a rotor, a rotary shaft connected to said rotor of said motor, a plurality of rotor blade cascades fixedly mounted on said rotary shaft, and a helically grooved rotor fixedly mounted on said rotary shaft and having an outer peripheral surface formed with a helical groove, said helically grooved rotor being located downstream of said rotor blade cascades.

Claim 5

A vacuum evacuation system as defined in claim 3, wherein said motor has a housing, and said helically grooved rotor is in the form of an annulus having an upper end wall to surround said housing of said motor.

Claim 6

A vacuum evacuation system as defined in claim 4, wherein said rotary shaft is arranged vertical­ly, and said helically grooved rotor is connected to said rotary shaft at said upper end wall.

Claim 7

A vacuum evacuation system comprising: first vacuum pump means including an outer case, an outlet, a rotor blade stage having stator blades fixedly secured to said outer case and rotor blades arranged in facing relation to said stator blades, for causing molecules to collide with each blade to produce a gas flow in a downstream direction, and a screw pump stage including a helically grooved rotor having an outer peripheral surface facing said outer case, said outer peripheral surface being formed with a helical groove, for delivering the gas from said rotor blade stage in the downstream direction by said helical groove; second vacuum pump means in communication with said outlet of said first vacuum pump means and includ­ing a casing, a pair of screw rotors having their respective shaft portions and rotatably housed within said casing in meshing relation to each other, each of said screw rotors having an outer peripheral surface formed with a plurality of helical irregularities, and sealing means disposed between said casing and the respective shaft portions of said pair of screw rotors; and drive means for respectively driving said first and second vacuum pump means.

Claim 8

A vacuum evacuation system comprising: first vacuum pump means including an outer case, an outlet, a rotor blade stage having stator blades fixedly secured to said outer case and rotor blades arranged in facing relation to said stator blades, for causing molecules to collide with each blade to produce a gas flow in a downstream direction, and a screw pump stage including a helically grooved rotor having an outer peripheral surface facing said outer case, said outer peripheral surface being formed with a helical groove, for delivering the gas from said rotor blade stage in the downstream direction by said helical groove; second vacuum pump means in communication with said outlet of said first vacuum pump means and includ­ing a casing, a pair of screw rotors having their respective shaft portions and rotatably housed within said casing in meshing relation to each other, each of said screw rotors having an outer peripheral surface formed with a plurality of helical irregularities, and sealing means disposed between said casing and the respective shaft portions of said pair of screw rotors; and drive means for respectively driving said first and second vacuum pump means.

Claim 9

A vacuum evacuation system as defined in claim 6, wherein said drive means includes first drive means fixedly secured to said outer case for driving said first vacuum pump means, and second drive means for driving said screw rotors of said second vacuum pump means.

Claim 10

A vacuum evacuation system as defined in claim 6, wherein said helically grooved rotor of said first vacuum pump means is in the form of an annulus having an upper end wall, the annular portion surround­ing said first drive means.

Claim 11

A vacuum evacuation system as defined in calim 8, wherein said helically grooved rotor is fixedly mounted to said first drive means at said upper end wall.

Claim 12

A vacuum evacuation system as defined in calim 8, wherein said helically grooved rotor is fixedly mounted to said first drive means at said upper end wall.

Claim 13

A vacuum evacuation system comprising: non-positive displacement type vacuum pump means including an outlet, rotor blade cascades having stator blades and rotor blades disposed in facing relation to said stator blades, for causing molecules to collide with the rotating rotor blades to produce a gas flow toward a downstream direction, and screw pump means having a helically grooved rotor having an outer peripheral surface formed with a helical groove, for delivering the gas from said rotor blade cascades by said helical groove; positive displacement type twin screw vacuum pump means including a casing having an inlet in com­munication with said outlet of said non-positive displacement type vacuum pump means, a pair of screw rotors having their respective shaft portions and rotatably housed within said casing in meshing relation to each other, each of said pair of screw rotors having an outer peripheral surface formed with helical ridges and valleys or grooves, and sealing means disposed between said casing and the respective shaft portions of said screw rotors; and drive means for driving said non-positive displacement type vacuum pump means and said positive displacement type vacuum pump means.

Claim 14

A vacuum evacuation system comprising: non-positive displacement type vacuum pump means including an outlet, rotor blade cascades having stator blades and rotor blades disposed in facing relation to said stator blades, for causing molecules to collide with the rotating rotor blades to produce a gas flow toward a downstream direction, and screw pump means having a helically grooved rotor having an outer peripheral surface formed with a helical groove, for delivering the gas from said rotor blade cascades by said helical groove; positive displacement type twin screw vacuum pump means including a casing having an inlet in com­munication with said outlet of said non-positive displacement type vacuum pump means, a pair of screw rotors having their respective shaft portions and rotatably housed within said casing in meshing relation to each other, each of said pair of screw rotors having an outer peripheral surface formed with helical ridges and valleys or grooves, and sealing means disposed between said casing and the respective shaft portions of said screw rotors; and drive means for driving said non-positive displacement type vacuum pump means and said positive displacement type vacuum pump means.