Hydrogen Engine Crankcase Venting Through Intake Pressure Control
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Solution Overview
Problem
Internal combustion engines using hydrogen as fuel face challenges in managing hydrogen concentration in the crankcase without the need for a ventilation fan, which would increase spatial constraints, especially when mounted on vehicles.
Innovation Solution
A controller that connects the crankcase and intake passage through a coupling passage, controlling the air-fuel ratio and executing a pressure reduction process in the intake passage when the engine output is low to reduce hydrogen concentration in the crankcase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ventilation fan is provided to discharge hydrogen gas from the crankcase, then hydrogen concentration in the crankcase is reduced, but spatial constraints increase due to mounting requirements
Solution Approach 1:
The invention extracts the harmful hydrogen gas from the crankcase through the existing coupling passage that connects to the intake passage, eliminating the need for a dedicated ventilation fan. The hydrogen is extracted and discharged into the intake passage where it is mixed with air-fuel mixture and combusted, thus removing the harmful substance without adding external ventilation equipment.
Solution Approach 2:
The coupling passage, originally designed for other purposes, is utilized for hydrogen gas discharge functionality. The intake passage serves dual purposes: normal air intake and hydrogen gas discharge pathway. The air-fuel mixture system handles both combustion and hydrogen disposal, making the system multi-functional and eliminating the need for dedicated hydrogen ventilation components.
2Power
If the air-fuel ratio is lowered to increase output, then engine power increases, but hydrogen concentration in the crankcase may increase
Solution Approach 1:
The system dynamically adjusts the air-fuel ratio based on operating conditions. When output is high and hydrogen concentration risk increases, the controller modifies the air-fuel ratio to maintain both power output and hydrogen concentration control. The pressure reduction process is also dynamically activated when target output is below a specific value to prevent hydrogen accumulation.
Solution Approach 2:
The controller monitors engine operating conditions including target output and adjusts the air-fuel ratio and pressure reduction process accordingly. When hydrogen concentration is expected to increase due to high output operation, the system activates pressure reduction and adjusts air-fuel mixing to maintain safety while preserving power output.
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
Reduces hydrogen concentration in the crankcase without a ventilation fan, preventing hydrogen leakage during maintenance by discharging it to the intake passage, thus ensuring safety and reducing spatial constraints.
Implementation Method 1
a pressure reduction process of reducing a pressure in the intake passage when the target output is less than a specific value
Data Source
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AI summary
An internal combustion engine (10) uses hydrogen as fuel. The internal combustion engine (10) includes a coupling passage (31, 32, 34, 35) that connects a crankcase (19) and a surge tank (60) to each other. A controller (100) executes a control of causing an air-fuel ratio of an air-fuel mixture to be lower when a target output of the internal combustion engine (10) is relatively high than when the target output is relatively low. The controller (100) executes a pressure reduction process of reducing a pressure in an intake passage (20, 29, 60) when the target output is less than a specific value. The pressure reduction process is a process of reducing the pressure in the intake passage (20, 29, 60) to be lower than that before the execution of the pressure reduction process.