Fuel Feed Control Using Aspirator Pressure to Prevent Vapor Lock
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Solution Overview
Problem
Conventional fuel-feeding devices for vehicles fail to prevent vapor lock in the fuel pump, which occurs when fuel vapors are generated in high temperature and low pressure environments, leading to engine stall or re-start delays.
Innovation Solution
Incorporating an aspirator that generates negative pressure in the fuel tank, a negative pressure sensor to detect this pressure, and a control device that adjusts the fuel pump's revolution speed based on detected negative pressure levels to anticipate and prevent vapor generation, thereby avoiding vapor lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel pump operates at normal revolution speed, then energy consumption is reduced and normal operation is maintained, but vapor lock occurs in high temperature and low pressure environments causing engine stall or re-start delay
Solution Approach 1:
The system performs preliminary detection of vapor generation conditions by monitoring negative pressure changes in the fuel tank before vapor lock actually occurs. When the negative pressure change amount exceeds a threshold, the control unit proactively increases fuel pump revolution speed to prevent vapor lock, rather than waiting for vapor lock to occur and then responding.
Solution Approach 2:
The system continuously monitors the negative pressure in the fuel tank using a pressure sensor and calculates the negative pressure change amount. This feedback information is used by the control unit to dynamically adjust the fuel pump revolution speed, increasing it when vapor generation is detected and reducing it when normal conditions return, thereby optimizing energy consumption while preventing vapor lock.
2Reliability
If the fuel pump revolution speed is increased to prevent vapor lock, then reliability is improved, but energy consumption increases
Solution Approach 1:
The system detects signs of vapor generation (negative pressure change exceeding threshold) before vapor lock fully develops and proactively increases fuel pump speed to prevent the condition, maintaining reliability while avoiding the need for sustained high-speed operation that would waste energy.
Solution Approach 2:
The fuel pump revolution speed is dynamically adjusted based on real-time detection of vapor generation conditions. The control unit increases speed only when necessary (when negative pressure change exceeds threshold) and reduces it when conditions normalize, optimizing the balance between reliability and energy consumption rather than maintaining a fixed high speed.
3Reliability
If conventional pressure sensor detection is used to identify vapor lock, then detection is simple, but vapor lock can only be detected after it occurs rather than prevented
Solution Approach 1:
The system monitors the negative pressure in the fuel tank and calculates the negative pressure change amount as an early indicator of vapor generation. When this change exceeds a predetermined threshold, the system proactively increases fuel pump speed to prevent vapor lock before it occurs, enabling prevention rather than just detection after the fact.
Solution Approach 2:
The control unit continuously receives feedback from the pressure sensor regarding negative pressure changes in the fuel tank. This real-time feedback enables the system to detect early signs of vapor generation and respond by increasing fuel pump speed before vapor lock develops, significantly reducing the response time compared to conventional post-detection methods.
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
The solution effectively prevents vapor lock in the fuel pump by increasing the revolution speed of the fuel pump when signs of vapor generation are detected, ensuring stable engine operation even in high temperature and low pressure conditions.
Implementation Method 1
an aspirator configured to generate a negative pressure therein using a flow of the fuel flowing through a branched conduit extending from the fuel-feeding conduit
Data Source
AI summary
A fuel-feeding device may include a fuel tank storing fuel therein, a fuel pump configured to feed the fuel in the fuel tank to an engine through a fuel-feeding conduit, an aspirator configured to generate a negative pressure therein using a flow of the fuel flowing through a branched conduit branched from the fuel-feeding conduit, a negative pressure sensor configured to detect the negative pressure generated by the aspirator, and a control device configured to control a revolution speed of the fuel pump. The control device is configured to determine a sign of vapor generation in the fuel stored in the fuel tank based on detection information of the negative pressure sensor.