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

2 The ultra high pressure pump according to claim 1 wherein the servo motor includes an encoder to count the frequency of rotation of the rotor shaft, the encoder being coupled to the servo motor via a closed feedback loop.

3 The ultra high pressure pump according to either claim 1 or 2 wherein the stator is located within a cylindrical housing.

4 The ultra high pressure pump according to claim 3 wherein the housing is encased in a cooling jacket.

5 The ultra high pressure pump according to any one of the preceding claims wherein the drive means comprises a linearly fixed nut that is in direct engagement with the rotor shaft, the nut threadedly engaging a screw whereby axial rotation of the rotor shaft, and therefore the nut, imparts linear motion to the screw.

6 The ultra high pressure pump according to claim 5 wherein pistons are coupled to opposite ends of the screw, each piston being adapted to complete reciprocal motion within an associated cylinder thus defined two pumping chambers.

7 The ultra high pressure pump according to either claim 5 or 6 wherein the screw is supported by linear bearings each supported on elongate rails.

8 A drive mechanism comprising a controller coupled to a servo motor having a stator coaxially mounted around a hollow rotor, the hollow rotor including drive means co-axially coupled to an output shaft whereby the drive means converts rotational movement of the rotor to linear displacement of the shaft and an encoder to measure movement of the rotor or output shaft and send a feedback signal proportional to the movement to the controller.

9 The drive mechanism according to claim 8, wherein the stator is co-axially located within a housing.

10 The drive mechanism according to either claim 8 or 9, wherein the output shaft drives a piston arranged within a cylinder to define a pumping chamber whereby alternating rotation of the rotor causes reciprocal linear displacement of the piston to pressurise fluid in the pumping chamber.

11 A linear actuator comprising a servo motor having a stator coaxially mounted around a hollow rotor, a drive member in engagement with the interior of the rotor, the drive member being constrained against linear movement and threadingly supporting a shaft to impart linear displacement of the shaft, and an encoder monitoring movement of the drive member or shaft and arranged to send a feedback signal to the servo motor whereby the operation and control of the servo motor causes controlled linear displacement of the shaft.

12 The linear actuator according to claim 11 wherein the stator includes windings of the motor.

13 The linear actuator according to either claim 11 or 12 wherein the rotor is elongate and supported for axial rotation about bearings at either end.

14 The linear actuator according to any one of claims 11 to 13 wherein the shaft is mounted on linear bearings supported by elongate rails.

15 The linear actuator according to any one of claims 11 to 14 wherein the encoder monitors rotational movement of the rotor.

16 The linear actuator according to any one of claims 11 to 14 wherein the encoder monitors linear displacement of the shaft.

17 The linear actuator according to any one of claims 11 to 16 wherein the stator is enclosed within a housing and a cooling jacket surrounds the housing.

18 The linear actuator according to claim 17 wherein the housing, cooling jacket, stator, rotor, drive member and shaft are all coaxial.