Variable-Displacement Piston Pump With ECU Direct Metering Control
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Solution Overview
Problem
Conventional hydromechanical control units in variable displacement piston pumps suffer from slow dynamic response times and inefficiencies during throttle transients, leading to potential fuel surges and reliability issues in high-pressure fuel systems for gas turbine engines.
Innovation Solution
A direct metering control system utilizing an electronic control unit (ECU) with a linear variable differential transducer (LVDT) and electrohydraulic solenoid valve (EHSV) to precisely control the pivot angle and actuator piston of the pump, enabling rapid and stable fluid flow adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional hydromechanical control unit is used in a variable displacement piston pump, then the system structure is simpler, but the dynamic response time is slow and pressure control precision deteriorates during throttle transients
Solution Approach 1:
The patent replaces the conventional hydromechanical control unit with an electronic control system comprising an electronic control unit (ECU), linear variable differential transducer (LVDT), and electrohydraulic solenoid valve (EHSV). This substitution of mechanical control with electronic control enables precise measurement of pivot angle via LVDT and rapid, accurate adjustment of fuel flow via EHSV, thereby improving both pressure control precision and dynamic response time during throttle transients.
Solution Approach 2:
The patent implements a feedback control mechanism where the LVDT continuously monitors the pivot assembly angle and provides feedback to the ECU. The ECU processes this feedback signal and adjusts the EHSV accordingly to maintain the desired pivot angle, enabling precise pressure control and rapid response to transient conditions through closed-loop feedback control.
2Productivity
If fuel is supplied too rapidly from excess fuel capacity systems, then fuel demand during operation conditions is met, but a rich mixture may cause a surge
Solution Approach 1:
The feedback control mechanism monitors pivot angle and fuel flow conditions, allowing the ECU to modulate the EHSV to maintain optimal fuel flow rates. This prevents excessive fuel supply that could cause rich mixtures and surges, while still meeting peak fuel demands through rapid, precise adjustments.
Solution Approach 2:
The patent employs dynamic control of the pivot assembly angle through the EHSV, enabling the fuel pump to rapidly adjust its displacement and fuel output in response to changing engine conditions. This dynamic adjustment capability allows the system to meet peak fuel demands while preventing oversupply conditions that could lead to fuel surges.
3Measurement precision
If an electronic control unit with LVDT and EHSV is implemented, then control precision and dynamic response are improved, but device complexity increases
Solution Approach 1:
The ECU serves multiple functions: it receives feedback from the LVDT, processes the signal to determine pivot angle, compares the actual angle with the desired angle, and controls the EHSV accordingly. This multi-functionality consolidates control logic into a single microprocessor-based unit, reducing overall system complexity despite the addition of electronic components.
Solution Approach 2:
The LVDT acts as an intermediary that converts mechanical pivot angle into an electrical feedback signal for the ECU. This intermediary component enables precise measurement without requiring direct mechanical connection between the pivot assembly and the control system, simplifying the mechanical interface while maintaining high measurement precision.
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 ECU provides rapid and accurate control of fluid flow, reducing the likelihood of fuel surges and enhancing the reliability and efficiency of high-pressure fuel systems by minimizing pressure ripple and stress fluctuations.
Implementation Method 1
a linear variable differential transducer (LVDT) operationally coupled to the pump controller and the actuator piston
Implementation Method 2
an electrohydraulic solenoid valve (EHSV) operationally coupled to the pump controller
Data Source
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AI summary
A variable displacement piston pump, having: a housing (170), a pivot assembly (190) to pivot between minimal and maximum pivot angles; a pump cover (350) defining an actuator bore with an actuator piston (370), an actuator arm (380) extending from the actuator piston to the pivot assembly; and an electronic control unit (ECU) coupled to the pump, the ECU having: a pump controller (400), a linear variable differential transducer (LVDT) coupled to the pump controller and the actuator piston, and an electrohydraulic solenoid valve (EHSV) coupled to the pump controller, the ECU is configured to: determine a pivot differential for the pivot assembly between a target pivot angle and a current pivot angle; determine a position differential for the actuator piston, corresponding to the pivot differential of the pivot assembly; control the EHSV to move the actuator piston by the position differential; and determine, from the LVDT, that the actuator piston moved by the position differential.