LPG Fuel Pump Housing Vapor Lock Prevention
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Solution Overview
Problem
Existing LPG fuel supply systems face challenges with vapor lock issues when the fuel pump is mounted inside the tank, requiring complete drainage for servicing, which is time-consuming and potentially dangerous, and external pumps are susceptible to vapor lock due to increased vapor pressure.
Innovation Solution
A fuel supply system with a fuel pump housed in a separate unit connected to the LPG tank via a vapor return line, allowing vapor to be released into the tank's vapor space, balancing pressures and preventing vapor lock, while the pump is located at or below the tank's bottom, with a vapor release port at the top of the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel pump is mounted inside the LPG tank, then the pump is protected from external heat sources, but the pump becomes susceptible to vapor lock due to heat generated from operating the fuel pump increasing vapor pressure
Solution Approach 1:
The system divides the pump housing into a liquid-filled lower portion and a vapor-permitting upper portion, with a vapor release port allowing vapor to escape from the upper portion. This segmentation allows the pump to operate in liquid LPG while preventing vapor lock by providing a dedicated vapor escape path.
Solution Approach 2:
A vapor release port acts as an intermediary element within the pump housing, providing a controlled path for vapor to escape from the pump chamber to the external environment or to a vapor recovery system, thereby preventing vapor accumulation and vapor lock.
2Ease of manufacture
If the fuel pump is mounted inside the LPG tank, then the pump is readily accessible for installation, but the pump requires complete draining of the LPG tank for servicing or replacement, which is time-consuming and potentially dangerous
Solution Approach 1:
The pump housing is designed as a separate, self-contained unit that can be installed and serviced independently from the LPG tank. This modular segmentation allows the pump to be removed and replaced without draining the entire tank, reducing service time and safety risks.
Solution Approach 2:
The pump housing includes integrated vapor release and liquid sealing features that are pre-configured during manufacturing. This preliminary action ensures that the pump can be quickly installed and sealed to the tank without requiring complex field modifications or complete tank drainage procedures.
3Ease of repair
If the fuel pump is mounted outside the LPG tank, then the pump can be serviced without draining the tank, but the pump becomes susceptible to vapor lock due to external heat exposure
Solution Approach 1:
The pump housing is segmented into a lower liquid intake portion that remains in or near the LPG tank and an upper vapor release portion that extends above the liquid level. This segmentation allows the pump to be serviced externally while maintaining the vapor lock prevention mechanism through the elevated vapor release port.
Solution Approach 2:
The vapor release port is positioned at a higher vertical dimension above the pump and tank, creating a pressure differential that prevents vapor from accumulating in the pump chamber. This dimensional elevation provides a natural vapor escape path that protects against vapor lock while allowing external pump access.
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 allows for safe and efficient servicing of the fuel pump without draining the LPG tank, preventing vapor lock and ensuring reliable operation by maintaining balanced pressures within the tank and pump housing.
Implementation Method 1
Vapor in the housing is allowed to return to the LPG tank through the action of gravity
Implementation Method 2
Vapor that forms in the fuel pump housing travels through the vapor return line and is released into the vapor space of the LPG tank, balancing the pressure in the LPG tank with the pressure in the fuel pump housing and thereby preventing vapor lock
Data Source
AI summary
A liquid petroleum gas (LPG) fuel supply system for a vehicle having an internal combustion engine includes an LPG tank, a fuel pump housing, a fuel pump inside the fuel pump housing, a fuel supply line connected between the LPG tank and the fuel pump housing, and a vapor release port located on the fuel pump housing. The vapor release port is connected to the LPG tank by a vapor return line. The fuel pump housing fills with LPG from the LPG tank under the action of gravity. Vapor forms in the fuel pump housing, separates from the liquid, gathers toward the top of the fuel pump housing, and under the action of gravity, displaces through the vapor port, rises through the vapor return conduit, and is released into the LPG tank 19, balancing pressure and preventing vapor lock.