Jet Pump Orifice Configuration for Fuel Priming
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Solution Overview
Problem
Fuel systems for internal combustion engines face challenges in minimizing the time required to prime the transfer tube, particularly when the fuel level is low and the engine operates under high fuel consumption and dynamic conditions, leading to potential fuel pump emptying before the transfer tube can be primed.
Innovation Solution
A jet pump assembly with a primary and secondary orifice configuration within the fuel system, where the secondary orifice impinges fuel onto the inner surface of the first fuel passage, creating a venturi effect that significantly reduces the priming time by drawing fuel into the passage, without the need for a jet pump in the secondary fuel tank portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a jet pump is located within the secondary fuel tank portion to reduce priming time, then the priming time is reduced, but the cost and complexity of delivering high pressure fuel to the secondary fuel tank portion increases
Solution Approach 1:
The patent introduces a secondary orifice positioned at a different spatial location and orientation relative to the first fuel passage, creating a multi-dimensional fuel injection pattern. This allows the jet pump in the primary tank portion to effectively prime the transfer tube without requiring physical relocation of the jet pump to the secondary tank portion, thus reducing priming time while avoiding the complexity of high-pressure fuel delivery systems to the secondary tank.
2Length of moving object
If the transfer tube is made longer to reach from the secondary fuel tank portion to the primary fuel tank portion, then fuel can be transferred between tanks, but the priming time becomes excessively long
Solution Approach 1:
The patent employs a secondary orifice that pre-primed the transfer tube by introducing fuel at multiple points along the passage before full operation begins. This preliminary action ensures the transfer tube is already filled with fuel when needed, eliminating the excessive priming time that would result from simply having a long transfer tube without active priming mechanisms.
3Productivity
If the primary orifice is directed centrally into the first fuel passage, then fuel flow is established, but the priming speed is insufficient under high fuel consumption conditions
Solution Approach 1:
The patent divides the single fuel injection point into two separate orifices: a primary orifice for central fuel injection and a secondary orifice for impinging fuel onto the inner surface of the first fuel passage. This segmentation creates multiple fuel flow paths and increases the overall fuel transfer rate, ensuring adequate priming speed even under high fuel consumption conditions where a single orifice would be insufficient.
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 reduces the priming time of the transfer tube from 9 seconds to 3 seconds, avoiding the added cost and complexity of delivering high-pressure fuel to the secondary fuel tank portion, while ensuring efficient fuel refill to the reservoir.
Implementation Method 1
The secondary orifice introduces a second flow of fuel into the first fuel passage which impinges an inner surface of the first tube such that the first flow of fuel and the second flow of fuel create a venturi effect within the first fuel passage which draws a third flow of fuel into the first fuel passage through the first fuel passage inlet
Data Source
AI summary
A fuel system includes a fuel pump and a jet pump assembly. The jet pump assembly includes a first fuel passage defined by a first tube. The jet pump assembly also includes a second fuel passage which receives pressurized fuel from the fuel pump, the second fuel passage having a primary orifice centered about and extending along a primary orifice axis such that the primary orifice axis is directed into the first fuel passage and such that the primary orifice introduces a first flow of fuel into the first fuel passage. The second fuel passage also has a secondary orifice centered about and extending along a secondary orifice axis which is not coincident with the primary orifice axis and which is directed at an inner surface of the first tube and the secondary orifice introduces a second flow of fuel into the first fuel passage which impinges the inner surface.