Inlet Valve Assembly Actuator Decoupling for Fuel Pump Reliability
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Solution Overview
Problem
Conventional inlet metering valves for high-pressure fuel pumps in common rail fuel injection systems are expensive, space-consuming, vulnerable to wear, and lead to delays in rail pressure control due to their complexity and sensitivity to dimensional tolerances and concentricity variations.
Innovation Solution
An inlet valve assembly with a poppet-type valve member, where closure is achieved by removing the opening force applied by a first biasing spring, allowing a second spring to close the valve, and using an electromagnetic actuator that compresses the first spring, decoupling the actuator from the valve member to accommodate dimensional variations and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional inlet metering valve is used to control fuel flow, then rail pressure control is achieved, but the system becomes expensive, space-consuming, and vulnerable to wear
Solution Approach 1:
The patent combines the metering function and inlet valve function into a single integrated component. The inlet valve assembly incorporates a metering needle that directly controls fuel flow into the pumping chamber, eliminating the need for a separate inlet metering valve. This integration reduces the number of parts, lowers cost, saves space, and improves reliability by removing potential failure points associated with multiple components and their interfaces.
Solution Approach 2:
The inlet valve assembly performs multiple functions simultaneously: it meters fuel flow through the adjustable needle, controls inlet flow to the pumping chamber, and serves as the inlet valve itself. This multi-functionality replaces what previously required separate dedicated components for metering and valve control, simplifying the overall system while maintaining precise control capabilities.
2Manufacturing precision
If a conventional inlet metering valve is used, then fuel flow is controlled, but dimensional tolerances and concentricity variations cause performance degradation
Solution Approach 1:
The inlet valve assembly is designed to be relatively insensitive to dimensional tolerances and concentricity variations through its self-adjusting geometry. The metering needle and seat arrangement creates a flow control mechanism that maintains performance despite manufacturing variations, reducing the need for tight tolerances while preserving reliable performance.
3Ease of operation
If the actuator is directly coupled to the valve member, then precise control is achieved, but wear and dimensional variations cause performance degradation
Solution Approach 1:
The patent introduces a magnetic coupling mechanism as an intermediary between the actuator and valve member. The actuator controls a plunger that moves a metering needle, which in turn controls fuel flow to the valve member. This indirect control through fuel pressure mediation reduces direct mechanical wear and allows the system to accommodate dimensional variations while maintaining precise controllability.
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
This design reduces manufacturing complexity and cost, enhances the valve's reliability and controllability by decoupling the actuator from the valve member, minimizing performance degradation due to wear, and allows for a larger flow rate while using a smaller coil, thus improving fuel delivery efficiency.
Implementation Method 1
an electromagnetic actuator that compresses the first spring
Implementation Method 2
a first biasing spring arranged to apply a first force to the valve member in an opening direction
Implementation Method 3
a second biasing spring arranged to apply a second force to the valve member in a closing direction
Data Source
AI summary
An inlet valve assembly for a high-pressure fuel pump is disclosed. The inlet valve assembly comprises an inlet valve member moveable between open and closed positions to control the fuel flow from a source of low-pressure fuel to a pumping chamber of the fuel pump, a first biasing spring arranged to apply a first force to the valve member in an opening direction, a second biasing spring arranged to apply a second force to the valve member in a closing direction, and an actuator arrangement operable to remove the first force from the valve member, thereby to allow the valve member to move into its closed position.