Asymmetrical Cam Fuel Pump for Noise Reduction
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Solution Overview
Problem
Existing fuel pump arrangements for high-pressure fuel injection systems face inefficiencies, particularly at low injection pressures, leading to increased noise, vibration, and waste of pressurized fuel, as they lack the ability to optimally control fuel volume and pressure.
Innovation Solution
A fuel pump arrangement with cam-driven pump units featuring asymmetrical cam profiles that allow for varying fuel volumes per pumping stroke, enabling efficient operation by using either a larger or smaller volume stroke based on demand, and incorporating metering valves and one-way valves to regulate fuel delivery and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional fuel pump arrangement with symmetrical cam profiles is used, then the pump can deliver fuel at high pressure, but it generates increased noise and vibration especially at low injection pressures
Solution Approach 1:
The patent applies asymmetry by providing cams with asymmetrical profiles that have different lobes. Each lobe corresponds to a different pumping stroke volume, allowing the pump to operate in different modes (single stroke or dual strokes) depending on fuel demand. This asymmetrical design enables the pump to reduce noise and vibration at low pressures by using only necessary strokes while maintaining efficient fuel delivery when needed.
Solution Approach 2:
The patent implements dynamics by making the pump operation adaptable through the asymmetrical cam profiles. The pump can dynamically switch between different operational modes (delivering fuel in one pumping stroke or in two pumping strokes) based on the fuel injection requirements. This dynamic capability allows optimization of noise and vibration characteristics while maintaining productivity across different operating conditions.
2Productivity
If the metering valve remains closed for the entire pumping stroke to maximize fuel delivery efficiency, then fuel delivery efficiency is improved, but pressurized fuel is wasted when rail pressure is already sufficient
Solution Approach 1:
The patent applies partial action by allowing the metering valve to be opened during the pumping stroke when rail pressure is sufficient. Instead of keeping the valve closed for the entire stroke to maximize efficiency, the system partially opens the valve to prevent wasteful pressurization of fuel that would otherwise be wasted. This partial action approach balances efficiency with energy conservation.
Solution Approach 2:
The patent implements feedback through the electronic control unit that monitors rail pressure and controls the metering valve operation. The ECU receives feedback about the current rail pressure state and adjusts the metering valve timing accordingly. When rail pressure is sufficient, the ECU opens the metering valve during the pumping stroke to prevent wasteful pressurization, thereby reducing energy loss while maintaining fuel delivery efficiency.
3Device complexity
If the pump operates with fixed cam profiles, then the mechanical structure is simple, but it cannot adapt to varying fuel injection demands across different operating conditions
Solution Approach 1:
The patent applies asymmetry by designing cams with asymmetrical profiles that have different lobes with different geometries. Each lobe is configured to produce a different pumping stroke volume. This asymmetrical design allows the pump to adapt to varying fuel injection demands by selectively using different lobes/strokes while maintaining a relatively simple mechanical cam structure. The asymmetry provides versatility without requiring multiple complex cam sets.
Solution Approach 2:
The patent implements universality by designing the asymmetrical cam system to perform multiple functions with a single cam structure. The same cam with its multiple lobes can deliver fuel in different volumes depending on which lobes are active during different operational modes. This multi-functionality allows the pump to adapt to varying fuel demands across different operating conditions while maintaining structural simplicity.
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 efficiency, reduces noise and vibration, and optimizes fuel delivery by allowing precise control of rail pressure, minimizing wastage and maintaining high pumping efficiency across different injection rates.
Implementation Method 1
a pumping element for pressurising fuel in the pumping chamber
Implementation Method 2
a one-way valve that allows fuel to flow only in the direction towards the fuel rail
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
A fuel pump arrangement for a fuel injection system is described. The fuel pump arrangement comprises one or more cam-driven pump units (110a, 110b), and the or each pump unit (110a, 110b) comprises a pumping chamber (112a, 112b) and a pumping element (114a, 114b) for pressurising fuel in the pumping chamber (112a, 112b). The or each pumping element (114a, 114b) is driven by a respective cam (116a, 116b) of the fuel pump arrangement to undergo at least one pumping stroke per revolution of the cam (116a, 116b). The fuel pump arrangement is configured such that the fuel volume displaced in a first pumping stroke is greater than the fuel volume displaced in a second pumping stroke. In this way, the efficiency of operation of the fuel pump arrangement can be improved.