Ultra high pressure pump with an alternating rotation to linear displacement drive mechanism
A high pressure pump including a linear actuator having a servo motor to axially rotate a hollow rotor shaft in alternating directions, the servo motor having a stator positioned co-axially around the hollow rotor shaft with an interior of the rotor shaft being co-axially coupled to a drive member to convert axial rotation into reciprocal displacement, the drive member being constrained against linear movement and supporting a shaft. At least one piston is coupled to the shaft and the piston is arranged within a cylinder to define a pumping chamber, whereby alternating rotation of the rotor shaft causes reciprocal linear displacement of the piston to pressurize fluid in the pumping chamber. A drive mechanism includes a controller coupled to a servomotor and an encoder to measure movement of the hollow rotor or output shaft and send a feedback signal proportional to the movement to the controller.
1. A pump, comprising:
two pistons, two cylinders, and two high pressure seals defining two pumping chambers; and
a drive mechanism configured to drive the pump to deliver fluid at 2 liters per minute and more than 50,000 psi for waterjet cutting with the fluid;
the drive mechanism comprising
a screw having ends each coupled to a respective one of the pistons;
a motor comprising a stator coaxially mounted around a hollow rotor comprising a nut portion co-operable with the screw to linearly drive the screw to pressurize the fluid in the pumping chambers;
an encoder configured to measure movement of the hollow rotor or the screw and send a feedback signal; and
a controller configured to control the motor by monitoring the feedback signal and electrical-current information coming back from the stator.
2. The pump of claim 1 , wherein the encoder is configured to count a frequency of rotation of the hollow rotor.
3. The pump of claim 1 , wherein the encoder is configured to send a velocity feedback signal and a position feedback signal.
4. The pump of claim 1 , wherein the hollow rotor is supported by an annular bearing; the screw is supported by rails and linear bearings co-operable with the rails; and the rails pass through the annular bearing.
5. A pumping arrangement, comprising:
a first pump in accordance with claim 1 ; and
a second pump in accordance with claim 1 and configured to operate out of phase relative to the first pump.
6. A waterjet cutting apparatus, comprising:
a cutting head; and
a pumping arrangement in accordance with claim 5 configured to supply the fluid to the cutting head.
7. A waterjet cutting apparatus, comprising:
a cutting head; and
a pump in accordance with claim 1 configured to supply the fluid to the cutting head.
8. The waterjet cutting apparatus of claim 7 , wherein the hollow rotor is supported by an annular bearing; the screw is supported by rails and linear bearings co-operable with the rails; and the rails pass through the annular bearing.
9. The waterjet cutting apparatus of claim 7 , wherein the cutting head has a hole between 0.1 mm and 0.5 mm in diameter.
10. A pump, comprising:
two pistons, two cylinders, and two high pressure seals defining two pumping chambers; and
a drive mechanism configured to drive the pump to deliver fluid at 2 liters per minute and more than 50,000 psi for waterjet cutting with the fluid;
the drive mechanism comprising
a screw having ends each coupled to a respective one of the pistons; and
a motor comprising a stator coaxially mounted around a hollow rotor comprising a nut portion co-operable with the screw to linearly drive the screw to pressurize the fluid in the pumping chambers;
the hollow rotor being supported by an annular bearing;
the screw being supported by rails and linear bearings co-operable with the rails; and
the rails passing through the annular bearing.
11. A pumping arrangement comprising
a first pump in accordance with claim 10 ; and
a second pump in accordance with claim 10 and configured to operate out of phase relative to the first pump.
12. A waterjet cutting apparatus, comprising:
a cutting head; and
a pumping arrangement in accordance with claim 11 configured to supply the fluid to the cutting head.
13. A waterjet cutting apparatus, comprising:
a cutting head; and
a pump in accordance with claim 10 configured to supply the fluid to the cutting head.
14. The waterjet cutting apparatus of claim 13 , wherein the cutting head has a hole between 0.1 mm and 0.5 mm in diameter.