Concentric Valve Fuel Pump Reducing Seal Failure
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Solution Overview
Problem
Existing fuel injection pump units face challenges with high operating pressures, leading to seal failures, increased fuel leakage, and operational inefficiencies due to differential radial expansion and high stresses induced by intersecting bores, which result in reduced reliability and increased fuel consumption.
Innovation Solution
The design incorporates a concentric valve system with an inlet valve member and an outlet valve member that move co-axially, eliminating the need for separate static and dynamic seals by forming a seal distal from the plunger head, and utilizing a higher Young's Modulus material for the barrel insert to reduce expansion and leakage, along with a sealing ring to minimize leakage past the plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static and dynamic seals are used to seal the pumping chamber, then sealing function is provided, but seal failure occurs due to differential radial expansion and fretting wear under high pressure cycles
Solution Approach 1:
The patent removes the separate static seal component from the system. Instead of using a distinct static seal between the pump head and barrel, the inlet valve member itself forms the seal surface. When the inlet valve member moves axially, it directly seals against the pump head, eliminating the need for a separate static seal that would be subject to differential radial expansion and fretting wear.
Solution Approach 2:
The inlet valve member performs multiple functions: it controls fuel flow into the pumping chamber and simultaneously provides the sealing function against the pump head. By combining the valve function and sealing function in a single component, the patent eliminates the separate static seal and reduces the number of sealing interfaces susceptible to failure.
2Productivity
If high pressure operation is implemented to improve fuel injection efficiency, then fuel consumption is reduced, but fuel leakage past the plunger increases due to radial expansion of the barrel
Solution Approach 1:
The patent changes the material parameter of the barrel, specifically using a material with a higher Young's Modulus. This material property change reduces the radial expansion of the barrel under high pressure, thereby maintaining the clearance dimensions and reducing fuel leakage past the plunger while still allowing high pressure operation for improved efficiency.
3Device complexity
If intersecting bores are used in the pump head design, then compact structure is achieved, but high stresses are induced requiring higher specification materials or specialised manufacturing
Solution Approach 1:
The patent divides the pump head into separate functional components: the pump head itself and the inlet valve member. By segmenting the sealing function into a separate movable inlet valve member rather than integrating it into the pump head structure, the design avoids creating high-stress concentrated zones that would require specialised manufacturing or higher specification materials.
4Reliability
If separate static and dynamic seals are provided in the pump unit, then sealing of the pumping chamber is achieved, but device complexity increases and reliability decreases
Solution Approach 1:
The patent merges the inlet valve function and the static sealing function into a single inlet valve member component. This component performs both functions simultaneously, eliminating the need for separate static and dynamic seals. The merging reduces device complexity while improving reliability by reducing the number of sealing interfaces that can fail.
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 configuration enhances the reliability and efficiency of the pump unit by reducing seal failures, minimizing fuel leakage, and lowering operational stresses, thereby improving the overall performance and reducing parasitic power loss and fuel consumption.
Implementation Method 1
the inlet valve member being movable between a first position and a second position; wherein the inlet valve member has an aperture formed therein, the aperture providing a first fluid pathway between the pumping chamber and the supply line when the inlet valve member is in said first position
Implementation Method 2
a plunger for pressurising fuel in the pumping chamber
Implementation Method 3
utilizing a higher Young's Modulus material for the barrel insert to reduce expansion and leakage
Data Source
AI summary
A pump unit has an inlet valve, an outlet valve, a supply line for supplying fuel, a pumping chamber, and a plunger for pressurizing fuel in the pumping chamber. The inlet valve includes an inlet valve member movable between a first position and a second position. The inlet valve member has an aperture formed therein. The aperture provides a first fluid pathway between the pumping chamber and the supply line when the inlet valve member is in its first position, and the aperture provides a second fluid pathway between the pumping chamber and the outlet valve when the inlet valve member is in its second position.