Fuel Injection Pressure Control to Prevent Return-Line Pressure Spikes
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Solution Overview
Problem
The fuel injection system experiences spike fuel pressure in the low pressure portion due to the opening of the relief valve, which can lead to deterioration of the low pressure portion, and existing solutions fail to effectively mitigate this issue.
Innovation Solution
A control device is introduced that includes a fuel pressure determination unit and a limiting unit within the fuel injection system, which determines when the high pressure portion's pressure exceeds a predetermined range and limits the fuel discharge of the low pressure pump to prevent spike fuel pressure by adjusting the feed pressure target value, thereby reducing the likelihood of relief valve opening and subsequent pressure spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relief valve is opened to reduce high pressure portion pressure, then the high pressure abnormality is relieved, but spike fuel pressure is generated in the low pressure portion causing deterioration
Solution Approach 1:
The control device performs preliminary action by detecting when the high pressure portion pressure approaches the valve opening pressure and proactively limiting the low pressure pump's fuel discharge before the relief valve opens. This prevents the pressure spike from occurring in the first place, rather than merely responding after the relief valve opens and causes damage.
Solution Approach 2:
The control device implements feedback control by continuously monitoring the high pressure portion pressure and using this information to adjust the low pressure pump's operation. When the pressure approaches the threshold, the control device provides feedback to limit fuel discharge, creating a closed-loop control system that prevents harmful pressure spikes.
2Productivity
If the low pressure pump continues full fuel discharge, then fuel supply efficiency is maintained, but spike fuel pressure occurs when relief valve opens
Solution Approach 1:
The control device takes preliminary action by detecting when high pressure portion pressure approaches the valve opening pressure and proactively limiting the low pressure pump's fuel discharge. This prevents the pressure spike condition from developing while maintaining normal operation during most conditions.
Solution Approach 2:
The control device applies partial action by limiting fuel discharge only when necessary (when high pressure portion pressure approaches the threshold), rather than continuously restricting flow. This maintains high fuel supply efficiency during normal operation while preventing harmful spikes when needed.
3Stress or pressure
If the relief valve opening pressure is set high, then fuel supply pressure is maintained, but the risk of spike fuel pressure increases
Solution Approach 1:
The control device uses feedback control to monitor high pressure portion pressure and adjust low pressure pump operation accordingly. This allows the relief valve opening pressure to be set at an appropriate level for fuel supply requirements while the feedback mechanism prevents dangerous pressure buildup that would cause spikes.
Solution Approach 2:
The control device acts as an intermediary between the low pressure pump and the high pressure portion, mediating the pressure relationship by limiting pump discharge when the high pressure portion pressure approaches critical levels. This intermediary control prevents the direct transmission of pressure spikes while maintaining adequate fuel supply pressure.
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 control device effectively lowers the spike fuel pressure and suppresses deterioration of the low pressure portion by limiting fuel discharge when the high pressure portion's pressure approaches the valve opening pressure, ensuring stable operation even when the relief valve is opened.
Implementation Method 1
The relief valve is provided in a high pressure portion provided downstream from the high pressure pump and opens when a high pressure abnormality occurs in the high pressure portion
Data Source
AI summary
A control device is included in a fuel injection system. The fuel injection system includes a low pressure pump, a high pressure pump, an accumulator, a fuel injection valve, a relief valve, and a return pipe. The high pressure pump increases a pressure of a fuel discharged from the low pressure pump and discharges high pressure fuel. The accumulator stores the high pressure fuel discharged from the high pressure pump. The relief valve is provided in a high pressure portion provided downstream from the high pressure pump and opens when a high pressure abnormality occurs in the high pressure portion. The return pipe returns the high pressure fuel in the high pressure portion to a low pressure portion provided downstream from the low pressure pump by the relief valve opening.