Fuel Injection Flow Control Valves for Limp Home Safety
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Solution Overview
Problem
Current fuel injection systems for piston engines face thermal problems due to excessive energy transformation and heat generation in safety valves when the control of flow control valves is lost, leading to inefficient engine operation in limp home mode.
Innovation Solution
The system incorporates at least two flow control valves between low-pressure and high-pressure pumps, with a mix of normally open and normally closed valves to control fuel flow precisely, reducing energy losses and heat formation by allowing controlled leakage, ensuring safe engine operation even without electrical control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all flow control valves are normally open to ensure full fuel delivery when control is lost, then engine safety in limp home mode is improved, but excessive heat generation occurs in the safety valve
Solution Approach 1:
The system divides the flow control into multiple independent valves (at least two flow control valves) that can be configured with different normal positions. This segmentation allows selective control of fuel flow to different high-pressure pumps, enabling the system to reduce total fuel flow and minimize heat generation in the safety valve while maintaining reliable operation in limp home mode.
Solution Approach 2:
Different flow control valves are assigned different normal positions (normally open or normally closed) based on their specific function and location in the system. This local differentiation allows the system to optimize both safety and heat generation reduction by having some valves default to closed position to limit flow and others default to open position to ensure safety, creating a balanced local quality distribution.
2Loss of energy
If flow control valves are normally closed to reduce heat generation in safety valve, then energy losses are reduced, but full fuel delivery capability is lost when control signal is lost
Solution Approach 1:
By segmenting the flow control system into multiple independent valves with different normal positions, the system can selectively close only the necessary number of valves to reduce heat generation while leaving others open to maintain adequate fuel delivery capability. This segmentation provides flexibility in balancing energy efficiency and reliability.
Solution Approach 2:
The system changes the normal position parameter of the flow control valves from uniform (all normally open or all normally closed) to differentiated (mix of normally open and normally closed). This parameter change allows the system to optimize the balance between reducing energy losses and maintaining full fuel delivery capability by adjusting the proportion and configuration of valves with different normal positions.
3Device complexity
If a single flow control valve configuration is used, then system complexity is reduced, but the ability to optimize both safety and energy efficiency is limited
Solution Approach 1:
The system segments the flow control function into multiple independent valves, each capable of being configured with different normal positions. This segmentation, while increasing the number of components, enables sophisticated control strategies that optimize both safety and energy efficiency by allowing selective operation of different valve configurations based on operating conditions.
Solution Approach 2:
The system implements dynamic configuration of flow control valves, where the normal position of each valve can be selectively changed based on operating requirements. This dynamic capability allows the system to adapt between different operational modes (normal operation, limp home mode, energy efficiency mode) by reconfiguring which valves are normally open or closed, optimizing productivity for each specific condition.
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 maintains engine power while minimizing energy losses and heat generation in safety valves, allowing for efficient operation in limp home mode by adjusting the ratio of normally open to normally closed valves and using multiple flow control valves to manage fuel flow rates accurately.
Implementation Method 1
a fuel accumulator (4, 4a, 4b, 4c) that is connected to the high-pressure pump(s) for receiving fuel at the second pressure level
Implementation Method 2
When the pressure of the fuel drops while it flows through the safety valve, potential energy stored in the pressurized fuel is transformed to heat, which is absorbed by the safety valve and the fuel that flows through the valve
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The fuel injection system for a piston engine (1) comprises a low-pressure pump (7, 7a, 7b, 7c), a high-pressure pump (5, 5a, 5b, 5c), a fuel accumulator (4, 4a, 4b, 4c) connected to the high-pressure pump(s) (5, a, 5b, 5c), a fuel injector (3) for injecting the fuel into a cylinder (2) of the engine (1), and at least two flow control valves (6a, 6b, 6c, 6d, 6e, 6f), which are arranged between a low-pressure pump (7, 7a, 7b, 7c) and a high-pressure pump (5, 5a, 5b, 5c) for controlling the amount of the fuel supplied to the high-pressure pump (5, 5a, 5b, 5c). At least one of the flow control valves (6a, 6b, 6c, 6d, 6e, 6f) is a normally open valve and at least one of the flow control valves (6a, 6b, 6c, 6d, 6e, 6f) is a normally closed valve.