Fuel Pressure Control Device Rapid Reduction Mechanism
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Solution Overview
Problem
Existing fuel pressure control systems in internal combustion engines face challenges in rapidly reducing fuel pressure in high-pressure passages during fuel cuts, leading to increased manufacturing costs and prolonged fuel cut execution times.
Innovation Solution
A fuel pressure control device with a low-pressure pump, high-pressure pump, and electronic control unit that utilizes first and second control valves and drive mechanisms to manage the suction and discharge passages, allowing for rapid reduction of fuel pressure by controlling the communication between the low-pressure and high-pressure passages based on the plunger's ascending and descending cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If both the suction valve and the discharge valve are opened by the drive mechanism to lower the fuel pressure in the high-pressure passage during the fuel cut, then the fuel pressure reduction is achieved, but the fuel may be sucked from the low-pressure passage side to the compressing chamber through the suction valve and then discharged from the compressing chamber to the high-pressure passage side, which hinders rapid reduction in fuel pressure
Solution Approach 1:
The invention divides the control function into two independent control valves: a first control valve for the suction passage and a second control valve for the discharge passage. This segmentation allows independent control of fuel flow paths, preventing the harmful backflow of fuel from the low-pressure passage to the high-pressure passage while maintaining effective pressure reduction.
Solution Approach 2:
The invention applies different control strategies to different passages: the first control valve is controlled to close during the descending period to prevent suction, while the second control valve is controlled to open during the ascending period to enable discharge. This localized differentiation of control quality optimizes the pressure reduction process.
2Stress or pressure
If a long relief passage is used to return the fuel from the high-pressure passage to the fuel tank, then the fuel pressure can be reduced, but the manufacturing costs increase
Solution Approach 1:
The invention introduces a control valve mechanism as an intermediary to manage fuel pressure reduction. Instead of relying on a long relief passage, the control valves actively regulate fuel flow through the existing suction and discharge passages, achieving pressure reduction without requiring extended passage lengths, thereby reducing manufacturing complexity and cost.
3Stress or pressure
If the technology continues fuel injection until the fuel pressure in the high-pressure passage reaches a target fuel pressure when a fuel cut condition is satisfied, then the fuel pressure is controlled, but the period of time from satisfaction of the fuel cut condition to execution of the fuel cut is prolonged
Solution Approach 1:
The invention prepares the control valves in advance: the first control valve is closed during the descending period before the fuel cut condition is fully satisfied, and the second control valve is opened during the ascending period. This preliminary positioning of control mechanisms enables rapid fuel pressure reduction once the fuel cut condition is met, eliminating the need to continue fuel injection until target pressure is reached.
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
Enables rapid reduction of fuel pressure in high-pressure passages, preventing excessive fuel injection and reducing manufacturing costs by efficiently managing fuel flow during fuel cuts.
Implementation Method 1
a first control valve provided in the suction passage, the first control valve being configured to permit or prohibit communication of the fuel between the low-pressure passage and the compressing chamber
Implementation Method 2
a second control valve provided in the discharge passage, the second control valve being configured to permit communication of the fuel from the compressing chamber to the high-pressure passage, and the second control valve being configured to restrict communication of the fuel from the high-pressure passage to the compressing chamber
Implementation Method 3
a plunger configured to ascend and descend inside the cylinder in conjunction with driving of the internal combustion engine, a compressing chamber having a capacity decreased by the plunger ascending and increased by the plunger descending
Data Source
AI summary
A fuel pressure control device determines whether it is during a descending period of a plunger descending or an ascending period of the plunger ascending, and puts a first drive mechanism and a second drive mechanism in an energized state during the descending period and in a non-energized state during the ascending period, when there is a pressure reduction request to lower a fuel pressure in a high-pressure passage.