Hybrid Engine Starting via Preliminary Fuel Rail Pressurization
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Solution Overview
Problem
Hybrid vehicles with direct fuel injection engines experience prolonged engine starting times due to the need to reestablish fuel pressure in the fuel rail, which delays the initiation of fuel injection and increases engine starting time.
Innovation Solution
The engine is rotated without supplying fuel to increase fuel pressure in the direct injection fuel rail before an engine start request, allowing for faster engine starting by pre-establishing the necessary pressure, thereby reducing the time required to start the engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is rotated to reestablish fuel pressure in the fuel rail before starting, then fuel injection can be initiated, but engine starting time is prolonged
Solution Approach 1:
The system performs preliminary fuel pressure buildup by rotating the engine with the disconnect clutch engaged before a start request is made. The fuel pump operates during this preliminary phase to establish fuel pressure in the rail, so that when the engine needs to start, fuel injection can begin immediately without waiting for pressure buildup, thus resolving the contradiction between ensuring fuel injection readiness and reducing starting time.
Solution Approach 2:
The engine starting process is segmented into distinct phases: a preliminary phase where the disconnect clutch is engaged and fuel pressure is built up, and a starting phase where the clutch is disengaged and the engine starts. This segmentation allows fuel pressure establishment to occur independently before the actual start, separating the fuel preparation function from the motor function and eliminating the delay between start request and fuel injection initiation.
2Stress or pressure
If the disconnect clutch is engaged during engine rotation to build fuel pressure, then fuel pressure is established, but engine speed increases which may cause unintended starting
Solution Approach 1:
Fuel pressure buildup is performed as a preliminary action before the actual engine start. The system rotates the engine with the disconnect clutch engaged during this preliminary phase to pressurize the fuel rail, then disengages the clutch before initiating combustion. This timing separation ensures that while the engine rotates during pressure buildup, the conditions for combustion are not yet present, preventing unintended starting while still achieving the desired fuel pressure.
Solution Approach 2:
The combustion function is extracted and separated from the engine rotation function. The system can rotate the engine independently to build fuel pressure without requiring combustion to occur. By taking out the combustion requirement from the rotation process, the system achieves fuel pressure establishment while maintaining precise control over when actual engine starting occurs, preventing unintended starting during the pressure buildup phase.
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 approach reduces engine starting time, improves vehicle drivability, and enhances engine emissions, leading to increased driver satisfaction.
Implementation Method 1
an engine may be rotated without supplying spark and fuel to the engine so that a direct injection fuel pump within the engine increases pressure within a direct injection fuel rail
Data Source
AI summary
Systems and methods for improving operation of a hybrid vehicle are presented. In one example, an engine is rotated to increase pressure within a fuel rail. The engine is rotated without combusting air and fuel within the engine.