High pressure liquid chromatography pump

摘要

A pump for use in high pressure liquid chromatography includes a housing with a pump head at one end and an axially-movable, high-pressure piston with a small-diameter plunger reciprocating within the pump head to move fluid from an inlet through an outlet at high pressure. An attached motor rotates a circular cam fixed off center on the motor shaft to reciprocate the piston that has an inner end in engaging contact with the cam periphery. An axially-aligned, torque-compensating piston is provided and has an inner end biased by spring force against the cam opposite the high-pressure piston. A large-diameter piston head may be fixed to the outer end of the torque-compensating piston and slidably mounted within a cylinder defined at the housing end opposite the pump head. The outer end of the piston head is open to ambient atmosphere.

主权项

1. A fluid pump for use in high pressure liquid chromatography comprising:
a housing having a drive case and a pump head at one end of the drive case defining an internal pump chamber communicating with an inlet and an outlet; a first piston supported by said housing for reciprocation along a first axis; a motor fixed to said housing rotating a shaft; a cam fixed to said shaft for rotation about a second axis transverse to said first axis, said cam having a peripheral edge intersecting said first axis; a first spring biasing said first piston along said first axis towards said cam; said first piston having an outer end with a plunger of lesser diameter than said first piston inward thereof movable in said pump chamber and an inner end engaging said cam edge so that said plunger may be reciprocated in said pump chamber upon rotation of said cam by said motor; a second piston supported by said housing for reciprocation along said first axis and having inner and outer ends, said cam being disposed between the inner ends of said pistons, said second piston outer end having an outer surface transverse to said first axis open to ambient atmosphere; a second spring biasing said second piston inner end towards said cam; and, wherein said second spring and atmospheric pressure in combination provide torque compensating force biasing said second piston inward against said cam opposing the inward force of said first piston on said cam.