Fuel Feed Apparatus Return Passage Pressure Loss Reduction
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Solution Overview
Problem
Conventional fuel feed apparatuses for internal combustion engines experience increased pressure loss and suction load, leading to potential component damage and reduced lifetime, particularly when inlet flow is increased to supply high-pressure fuel effectively, and enlarging the inlet pipe to reduce pressure loss results in an excessively large apparatus.
Innovation Solution
A fuel feed apparatus with a return passage and return flow control unit that allows fuel to return from downstream to upstream of the feed pump, reducing pressure loss and maintaining a compact size by controlling fuel flow through a return valve that opens before the relief valve, thus minimizing the need for an enlarged inlet pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet flow of the feed pump is increased to properly supply fuel to the high-pressure pump, then fuel supply capability is improved, but pressure loss between the fuel tank and feed pump increases, causing suction load increase and potential abnormal ablation of feed pump components
Solution Approach 1:
A return passage is introduced as an intermediary component that allows fuel to flow back from the downstream side of the feed pump to the upstream side. This mediator enables pressure equalization and reduces suction load without requiring increased inlet flow, thus resolving the contradiction between fuel supply capability and pressure loss.
2Loss of energy
If the diameter of the inlet pipe between the fuel tank and feed pump is increased to decrease pressure loss, then pressure loss is reduced, but the fuel feed apparatus becomes excessively large
Solution Approach 1:
The return passage acts as a mediator that reduces pressure loss through internal recirculation rather than by enlarging external components. This allows pressure loss to be decreased without increasing the apparatus volume, as the return passage utilizes existing space within the feed pump assembly.
Solution Approach 2:
The system changes the flow parameters by introducing a return flow path that alters the pressure distribution within the feed pump. By changing the flow configuration rather than the physical dimensions, pressure loss is reduced without enlarging the apparatus.
3Loss of energy
If a return passage is added to reduce pressure loss, then pressure loss and suction load are reduced, but the device complexity increases
Solution Approach 1:
The return passage is merged with the existing feed pump structure, integrating the pressure loss reduction function into the current device rather than adding a separate external system. This combining approach minimizes the increase in device complexity while achieving the desired pressure loss reduction.
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 solution reduces pressure loss and extends the lifetime of the feed pump while maintaining a compact apparatus size, ensuring efficient fuel supply to the high-pressure pump and preventing fuel filter plugging, even at low temperatures.
Implementation Method 1
a return passage for returning fuel from a downstream of the feed pump to an upstream of the feed pump
Implementation Method 2
a fuel filter provided downstream of the feed pump for filtering fuel
Data Source
AI summary
A fuel feed apparatus is provided for supplying high-pressure fuel to a common rail of an accumulator fuel injection system. The accumulator fuel injection system includes an injector for injecting high-pressure fuel accumulated in the common rail into a combustion chamber of an internal combustion engine. The fuel feed apparatus includes a high-pressure pump for press-feeding fuel to the common rail, and a feed pump for pumping fuel from a fuel tank to the high-pressure pump. A fuel filter is provided downstream of the feed pump for filtering fuel pumped from the feed pump. A return passage is provided for returning fuel from a downstream of the feed pump to an upstream of the feed pump. A return flow control unit is provided for controlling fuel retuning through the return passage.