Vacuum pump

An integral vacuum pump for evacuating a fluid, such as air, from a sealed chamber as in a scientific instrument of the type of an electron microscope comprising:

• a housing having an inlet to be connected in sealed relation to said chamber and an exhaust at an opposite end thereof;
• a shaft axially disposed in said housing;
• motor means for providing rotary motion to said shaft;
• axial flow turbomolecular pumping means disposed in said housing, adjacent said inlet, and alternately including stators fixedly secured to said housing and rotors fixedly secured to said shaft, said rotors being in juxtaposed relation to said stators to provide turbomolecular pumping;
• centrifugal compressor pumping means disposed in said housing intermediate said axial flow turbomolecular pumping means and said exhaust, including stators fixedly secured to said housing and rotor fixedly secured to said shaft, said rotors being in juxtaposed relation to said stators to provide centrifugal compressor pumping;
• fluid diode pumping means disposed in said housing intermediate said centrifugal compressor pumping means and said exhaust including stators fixedly secured to said housing and rotors fixedly secured to said shaft, said rotors being in juxtaposed relation to said stators.