PWM Fuel Transfer Pump with Multi-Mode Control
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Solution Overview
Problem
Existing fuel transfer pump systems, including mechanically and electric motor driven pumps, face issues such as seal damage, inefficient energy use, and increased maintenance costs due to direct RPM correlation with engine speed, leading to excessive fuel flow and energy wastage, particularly in applications like locomotives where fuel needs to be lifted over long distances.
Innovation Solution
A pulse width modulated (PWM) fuel transfer pump system with an AC Induction motor and a multi-mode control process that dynamically controls the motor speed based on measured fuel pressure and current, allowing for efficient fuel delivery to a high-pressure fuel injection pump, adapting to various engine conditions and voltage fluctuations, and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanically driven fuel transfer pump is used with dynamic shaft seal, then fuel transfer capability is achieved, but seal damage and leakage occur due to wear and debris
Solution Approach 1:
The patent replaces the mechanically driven pump with an electric motor-driven pump, eliminating the dynamic shaft seal that connects rotating and stationary parts. The electric motor drives the pump through a sealed interface, preventing fuel leakage while maintaining pumping capability. This substitution of mechanical drive with electric drive resolves the seal reliability issue.
2Productivity
If mechanically driven fuel transfer pump RPM is tied to engine speed, then fuel delivery is synchronized with engine operation, but excessive fuel flow is generated leading to energy wastage
Solution Approach 1:
The patent implements a controlled electric motor drive that dynamically adjusts pump RPM based on actual fuel consumption requirements rather than being mechanically coupled to engine speed. The control system monitors fuel demand and motor current, adjusting pump speed accordingly to deliver precise fuel amounts without excessive flow that would require draining back to tank, thereby eliminating energy wastage.
Solution Approach 2:
The system uses feedback from fuel pressure sensors and motor current monitoring to regulate pump operation. The control unit receives signals about actual fuel delivery conditions and adjusts motor speed in real-time to match demand, preventing both under-delivery and over-delivery of fuel that would waste energy.
3Speed
If mechanically driven fuel transfer pump is used at low engine RPM, then engine operation is maintained, but insufficient lift capability prevents fuel delivery from low-positioned tanks
Solution Approach 1:
The electric motor-driven pump provides sufficient lifting capability at all engine speeds including idle and cranking conditions. The electric motor can generate high torque at low speeds, easily overcoming the 6-foot lift requirement from low-positioned fuel tanks without being constrained by engine RPM, ensuring reliable fuel delivery in all operating conditions.
4Reliability
If DC motor driven fuel transfer pump is used, then electrical fuel transfer is achieved, but motor brush wear increases maintenance costs and failure risk
Solution Approach 1:
The patent uses an AC induction motor with sealed bearings instead of a DC motor with brush assemblies. The AC motor design eliminates carbon brushes that wear down and require replacement, significantly reducing maintenance requirements and improving reliability for continuous duty applications. The sealed bearing interface prevents fuel contamination while maintaining motor performance.
5Stress or pressure
If fuel is bypassed back to tank to regulate pressure, then pressure control is achieved, but heat is added to fuel and pump components wear faster
Solution Approach 1:
The controlled electric motor pump varies its speed to match fuel demand, delivering fuel at the required flow rate and pressure without excessive flow that would need to be bypassed. By dynamically adjusting pump RPM based on actual consumption needs, the system maintains pressure control while eliminating the energy-wasting bypass operation and associated heat generation.
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 PWM fuel transfer pump system reduces energy wastage, extends filter life, and lowers maintenance costs by optimizing fuel delivery and motor operation, ensuring efficient fuel transfer across a range of engine conditions while minimizing current inrush and adapting to voltage variations.
Implementation Method 1
an AC induction motor and a pulse width modulation (PWM) controller for controlling the AC induction motor
Implementation Method 2
A pulse width modulated (PWM) fuel transfer pump system with an AC Induction motor and a multi-mode control process
Data Source
AI summary
A Fuel transfer pump system comprising a multi-mode control process for transferring fuel. The multi-mode control process comprising a closed loop pressure control mode for maintaining fuel pressure at an outlet of a fuel transfer pump at a substantially constant target pressure and having a soft start mode for bidirectionally ramping up to the target pressure by utilizing an open loop control in combination with the closed loop pressure control mode; a current control mode dynamically switchable from the closed loop pressure control mode for controlling a motor driving the fuel transfer pump as a function of a predetermined current threshold; a DC-bus voltage compensation mode operable with either the closed loop pressure control mode or the current control mode for compensating DC bus voltage sag; and an open loop ramp down mode for ramping open loop motor RPMs to zero from any other mode for shutting down system operation.