Self-Regulating Common Rail Pump for GDI Systems
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Solution Overview
Problem
Gasoline direct injection (GDI) fuel systems are costlier than conventional metered pump inlet systems due to the need for expensive solenoid-operated control valves, electronic control requirements, and additional costs from on-board diagnostics and electrical hardware.
Innovation Solution
A simplified GDI single piston pump design eliminates electronic control, using a delivered pressure regulator to maintain constant pressure and an inlet metering valve to vary flow, with hydraulic or mechanical responsiveness to pressure changes, and a check valve to prevent pressure loss during engine shutdown, reducing heat generation and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a solenoid-operated control valve and electronic control system are used to regulate pump pressure, then pressure control precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the solenoid-operated control valve and electronic control system with a purely mechanical pressure regulating element that responds directly to rail pressure changes. The pressure regulating element mechanically adjusts the inlet metering valve position based on pressure feedback, eliminating the need for electronic sensors, solenoids, and control circuitry while maintaining pressure control precision.
Solution Approach 2:
The pressure regulating element operates autonomously by directly sensing rail pressure changes and automatically adjusting the inlet metering valve accordingly. This self-regulating mechanism eliminates the need for external electronic control systems, OBD, and software code, simplifying the device while maintaining precise pressure control.
2Measurement precision
If a solenoid-operated control valve and electronic control system are used to regulate pump pressure, then pressure control precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive electronic components (solenoid control valve, electronic control device, sensors, wiring) with a simple mechanical pressure regulating element. This substitution dramatically reduces manufacturing cost while maintaining pressure control precision through pure mechanical pressure-responsive operation.
Solution Approach 2:
The mechanical pressure regulating element uses simple, inexpensive components that can be manufactured at low cost compared to electronic control systems. The design eliminates expensive electronic hardware in favor of affordable mechanical parts that achieve the same pressure control function.
3Device complexity
If the pump operates without pressure regulation during engine shutdown, then device complexity is reduced, but fuel boiling occurs due to pressure loss
Solution Approach 1:
The patent extracts the pressure maintenance function as a separate, dedicated check valve mechanism that operates independently during engine shutdown. This check valve specifically prevents pressure loss and fuel boiling in the rail when the pump stops operating, without adding complex electronic control systems.
Solution Approach 2:
The check valve is positioned to automatically maintain pressure in the common rail before the pump fully shuts down. This preliminary pressure maintenance action prevents fuel boiling during hot soak conditions by ensuring sufficient pressure remains in the rail even when the pump is not operating.
4Device complexity
If excessive high pressure fuel is spilled during mid to high speed operation, then pressure regulation is simplified, but heat generation increases
Solution Approach 1:
The patent implements a feedback mechanism where the pressure regulating element continuously monitors rail pressure and automatically adjusts the inlet metering valve to match pump output with actual engine demand. This closed-loop feedback control minimizes excessive fuel spillage and the associated heat generation while maintaining simple pressure regulation.
Solution Approach 2:
The inlet metering valve is designed to dynamically adjust its opening based on engine speed and demand conditions. During mid to high speed operation, the valve automatically reduces metering to minimize fuel spillage and heat generation, while maintaining adequate flow during low speed operation.
Data Source
AI summary
The pump delivered pressure is regulated to a substantially constant set value, and output flow is varied by an inlet metering valve (5) via feedback from the motion of, or flow from the spilled fuel through, a delivered pressure regulator (13, 19). The pressure regulating element can be biased to close a seal surface (12′) against flow from the outlet side of the pump (14) toward the inlet metering valve when the pump is turned off, thereby holding sufficient rail pressure to prevent boiling during hot soak conditions. In another aspect, a flow stabilization orifice (18) is provided between the outlet of the pump and the inlet metering valve, e.g., upstream of the pressure regulating element. In yet a further aspect, the inlet metering valve is hydraulically responsive (6, S, L) to changes in flow resulting from movement of the pressure responsive element (13).