Other

Beckman Instruments, Inc.

Spectra-Physics Gmbh

Williams G Patterson

Leslie A Miller

Kenneth E Jacobson

Martin P Bradley

William S Gutierrez

Allen B Rochkind

A pump for producing a substantially smooth and continuous outflow of liquid at relatively high pressure has two piston assemblies flow connected in series. The first piston assembly includes a pressure piston having a long suction stroke and a relatively short and abrupt expulsion stroke. A valve at the inlet of the pressurization piston allows flow to enter (but not exit), and a valve at the outlet of the pressurization piston allows flow to exit (but not enter). The second piston assembly includes a damper piston which functions as a mechanically driven damper to smooth the outflow from the pressure piston. This smoothing is accomplished by storing of the liquid displaced by the expulsion stroke of the pressure piston and then delivering the stored pressurized liquid to the pump outlet during the suction stroke of the pressure piston. The drive for the pistons is constructed to produce an increased outflow of pressurized liquid for a short interval at the beginning of the expulsion stroke of the pressure piston to compensate for compressibility of the liquid at high pressure. At low pressure, the stepper motor drive is slowed down in response to the sensing of the increase of the outflow during this short interval to maintain the outflow smooth and continuous during this part of the cycle of operation.

Dual piston pump

A lubricating system which is completely self contained within the vacuum environment of an electric direct drive system for an ultracentrifuge rotor. The lubricating system also functions as a cooling means for an electric motor within the drive system by the use of a unique cooling feed tube in the central portion of the drive system. An orifice in the top of the cooling feed tube will control the head of the lubricating medium within the system. Specific design of the fit between the direct drive assembly and the drive housing in conjunction with the head on the lubricating medium will regulate the drip rate of the lubricating medium to the bearings. The use of the unique lubrication and cooling system maintains the close tolerances of the various elements such as the high speed bearings of the drive system because the temperature of the overall drive system is controlled.

Lubrication and cooling system for a high speed ultracentrifuge drive

A high vacuum turbomolecular pump is described incorporating a drive system which significantly reduces the amount of heat build-up therein. The pump includes an outer casing having an upper open end adapted to be communicated hermetically with an isolated environment to be pumped, and an exhaust opening at its lower end. A plurality of vertically spaced stator blade wheels are positioned within the casing intermediate the inlet and exhaust openings, and a rotor is mounted within the casing on a spindle for rotation therewith on a generally vertical axis. The rotor is provided with a plurality of axially spaced rotor blade wheels interleaved with the stator blade wheels. An electrical induction motor is incorporated into the pump with its rotor output shaft being the spindle so as to rotate such spindle and, hence, the pump rotor for high vacuum pumping. A photosensor is included for sensing the frequency of rotation of the pump rotor and a slip frequency oscillator is provided to generate a desired constant slip frequency. A control circuit is included for combining the desired slip frequency with the pump rotor frequency of operation in order to drive the stator of the motor with a constant slip frequency.

Turbomolecular pump drive method and apparatus

A high vacuum turbomolecular pump is described having a lubrication system which assures steady, continuous lubrication of the rotor bearings. The pump includes an outer casing having an upper open end adapted to be communicated hermetically with an isolated environment to be pumped, and an exhaust opening at its lower end. A plurality of vertically spaced stator blade wheels are positioned within the casing intermediate the inlet and exhaust openings, and a rotor is mounted within the casing on a spindle for rotation therewith on a generally vertical axis. The rotor is provided with a plurality of axially spaced rotor blade wheels interleaved with the stator blade wheels. An electrical induction motor is incorporated within the pump for rotating the spindle and, hence, the pump rotor, for high vacuum pumping. Such spindle is supported for rotation by a pair of bearings positioned on opposite sides of the induction motor and has an axial passageway designed to draw fluid lubricant upwardly therealong by centrifugal action during its rotation. The lower end of the spindle extends into a reservoir of fluid lubricant. A cup surrounds the spindle lower end to isolate the exterior of the spindle from lubricant within the reservoir, and a nozzle communicating with the reservoir extends into the inlet orifice of the passageway to feed fluid lubricant into the same without such lubricant having to contact the external rotating surfaces of the spindle.

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Palo Alto, CA, United States of America

Williams G Patterson