Servo-Driven Ultra-High Pressure Pump for Low-Pulsation Waterjet Cutting
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Solution Overview
Problem
Current ultra-high pressure waterjet pumps, such as intensifier and direct drive crank shaft pumps, are inefficient and unreliable, with intensifiers running at 55% efficiency and direct drive pumps consuming similar power whether idle or in operation, and experiencing pressure pulsation due to piston reciprocation, leading to early fatigue and maintenance challenges.
Innovation Solution
A servo motor-driven ultra-high pressure pump with a hollow rotor and pistons operating in tandem, utilizing a feedback loop and encoder for precise control, allowing for efficient operation at pressures over 345 MPa (50,000 psi) with minimal power consumption and reduced pulsation through phased operation of dual pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If direct drive crank shaft pumps are used to achieve high efficiency water pressurization, then efficiency exceeds 80%, but the pump cannot store and hold pressure, consuming similar power whether idle or in operation
Solution Approach 1:
The patent employs a servo motor that can dynamically adjust its operation between continuous rotation mode (for high-speed cutting) and idle mode (for pressure holding). The servo motor's ability to maintain position without continuous power consumption allows the system to hold pressure reliably while consuming minimal power during idle periods, resolving the contradiction between efficiency and pressure holding capability.
2Productivity
If direct drive crank shaft pumps operate at high piston speed to increase productivity, then water output increases, but pressure pulsation causes early fatigue and maintenance challenges
Solution Approach 1:
The patent utilizes dual pumps operating out of phase with each other, where one pump is pressurizing water while the other is delivering it. This periodic alternation smooths out pressure pulsations that would otherwise occur with single-pump reciprocating operation, reducing fatigue on components while maintaining high productivity through continuous operation.
3Reliability
If intensifier pumps are used to achieve reliable pressure delivery, then reliability is improved, but efficiency drops to 55% due to hydraulic system losses
Solution Approach 1:
The patent replaces the hydraulic intensifier system with a direct mechanical servo motor-driven reciprocating pump. This eliminates the intermediate hydraulic fluid transmission stage that causes energy losses in intensifier pumps, achieving high efficiency through direct mechanical coupling while maintaining reliable pressure delivery through precise servo control.
4Ease of operation
If high pressure water is continuously pressurized to maintain readiness, then immediate cutting capability is improved, but power consumption remains high during idle periods
Solution Approach 1:
The servo motor system can maintain pressure readiness through precise control algorithms that keep the pump at optimal standby positions without continuous operation. The system serves itself by using minimal power to maintain readiness state, only consuming full power when actual cutting operation is required, thus resolving the contradiction between immediate cutting capability and idle power consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The servo motor-driven pump achieves high efficiency and reliability, maintaining pressure without cutting, reducing power usage and pulsation, extending component life, and enabling precise pressure control, while being compact and quieter than traditional systems.
Implementation Method 1
a servo motor adapted to axially rotate a hollow rotor shaft in alternating directions
Implementation Method 2
The drive means comprises a linearly fixed nut that is threadedly engaged with the rotor shaft. The nut threadedly engaging a screw whereby axial rotation of the rotor shaft and rotor nut imparts reciprocal motion to the screw.
Implementation Method 3
the drive means being coupled to at least one piston having a head arranged within a cylinder to define a pumping chamber between the head of the piston and the cylinder, whereby alternating rotation of the rotor shaft causes reciprocal linear displacement of the piston to pressurise fluid in the pumping chamber
Data Source
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AI summary
An ultra-high pressure pump comprising two pistons (50, 51), two cylinders (54, 55), and two high pressure seals (70, 71) defining two pumping chambers (58, 59). The pump further comprising a drive mechanism capable of driving the pump to deliver fluid at more than 345 MPa (50,000 psi) for waterjet cutting. The drive mechanism comprises a servo motor (15, 19) comprising a hollow rotor (15) and a stator (19) coaxially mounted around the hollow rotor, an output shaft (31) having ends and a controller (82, 83, 84) coupled to the servo motor. Each of the ends of the output shaft (31) is coupled to a respective one of the pistons. The hollow rotor includes drive means (30) co-axially coupled to the output shaft whereby the drive means converts rotational movement of the hollow rotor to linear, reciprocal displacement of the output shaft to pressurize the fluid in the pumping chambers. The drive mechanism further comprises an encoder (80) configured to measure movement of the hollow rotor or the output shaft and to send a feedback signal to the controller. The controller is configured to control the servo motor by monitoring the feedback signal and electrical-current information coming back from the stator.