Ultra high pressure pump with an alternating rotation to linear displacement drive mechanism

An ultra high pressure pump, comprising:

• a servo motor;
• a hollow rotor shaft;
• drive means;
• at least one piston;
• at least one cylinder;
• and
• at least one pumping chamber;
• the servo motor being adapted to axially rotate the hollow rotor shaft in alternating directions;
• the servo motor having a stator positioned co-axially around the hollow rotor shaft;
• the hollow rotor shaft being co-axially coupled to the drive means;
• the drive means being configured to convert axial rotation into reciprocal displacement;
• the servo motor including an encoder to monitor movement of at least one of the hollow rotor shaft and the drive means;
• the encoder being coupled to the servo motor via a closed feedback loop;
• the at least one piston having a head arranged within the at least one cylinder to define the at least one pumping chamber between the head and the at least one cylinder;
• the drive means being coupled to the at least one piston such that alternating rotation of the hollow rotor shaft causes reciprocal linear displacement of the at least one piston to pressurize fluid in the at least one pumping chamber;
• the drive means being coupled to an interior of the hollow rotor shaft;
• and
• the pressurizing being to pressures greater than 345 MPa (50,000 psi);
• the drive means including a nut, which is in direct engagement with the hollow rotor shaft and which threadedly engages a screw whereby axial rotation of the hollow rotor shaft, and corresponding axial rotation of the nut, imparts linear motion to the screw;
• the screw being supported by linear bearings each supported on elongate rails, with the linear bearings preventing rotation of the screw while facilitating longitudinal movement of the screw;
• and
• one end of the hollow rotor shaft being supported by an annular bearing and the rails passing through the annular bearing.

An ultra high pressure pump, comprising:

• a servo motor;
• a hollow rotor shaft;
• drive means;
• at least one piston;
• at least one cylinder;
• and
• at least one pumping chamber;
• the servo motor being adapted to axially rotate the hollow rotor shaft in alternating directions;
• the servo motor having a stator positioned co-axially around the hollow rotor shaft;
• the hollow rotor shaft being co-axially coupled to the drive means;
• the drive means being configured to convert axial rotation into reciprocal displacement;
• the servo motor including an encoder to monitor movement of at least one of the hollow rotor shaft and the drive means;
• the encoder being coupled to the servo motor via a closed feedback loop;
• the at least one piston having a head arranged within the at least one cylinder to define the at least one pumping chamber between the head and the at least one cylinder;
• the drive means being coupled to the at least one piston such that alternating rotation of the hollow rotor shaft causes reciprocal linear displacement of the at least one piston to pressurize fluid in the at least one pumping chamber;
• the drive means being coupled to an interior of the hollow rotor shaft;
• the pressurizing being to pressures greater than 345 MPa (50,000 psi);
• the drive means including a nut that is in direct engagement with the hollow rotor shaft and that threadedly engages a screw whereby axial rotation of the hollow rotor shaft, and corresponding axial rotation of the nut, imparts linear motion to the screw;
• the at least one piston being one of two pistons,
• the at least one cylinder being one of two cylinders,
• the two pistons being coupled to opposite ends of the screw, and
• each of the two pistons being adapted to complete reciprocal motion within an associated one of the two cylinders, whereby the at least one pumping chamber is one of two pumping chambers;
• each of the two cylinders having a low pressure water inlet controlled by a low pressure check valve and a high pressure outlet controlled by a high pressure check valve;
• there being a high pressure seal positioned between an inner end of each of the two pistons and a respective one of the two cylinders;
• and
• each of the two pistons having a stroke length of about 175 mm and reciprocating at about 120 strokes per minute to deliver between 2 and 4 liters of the fluid per minute.