Gas Metering Unit With Two-Stage Pressure Regulation for CNG Range
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Solution Overview
Problem
Internal combustion engines operating with compressed natural gas face challenges in efficiently metering gas due to high pressure requirements, leading to reduced vehicle range and complex, costly systems that struggle with dynamic operation and emission control.
Innovation Solution
A metering unit with a gas pressure regulator and an electrically regulated fuel gas metering valve, where the gas pressure regulator is connected upstream to reduce the control range of the fuel gas metering valve, allowing for precise and dynamic gas management, including a primary and main pressure regulator, pressure relief valve, and compensation elements to adapt to varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high feed pressure of about 8 bar is maintained to ensure full load operation with gas injection valves, then the engine can achieve full load performance, but a large amount of gas must remain in the gas tank to maintain this pressure level, which limits the vehicle range
Solution Approach 1:
The patent implements dynamic pressure regulation by replacing the static 8 bar feed pressure requirement with an electronically regulated metering valve that adapts the gas pressure and flow rate according to real-time engine operating conditions. This allows the system to maintain full load performance when needed while permitting the gas tank pressure to drop to lower levels (down to 2 bar) as the tank empties, thereby extending vehicle range without sacrificing engine performance capability.
Solution Approach 2:
The system changes the operating parameters of gas pressure and flow rate dynamically based on engine load requirements. The electronically regulated metering valve adjusts these parameters in real-time, allowing the feed pressure to vary from minimum levels (extending range) to sufficient levels (maintaining performance) rather than maintaining a constant high pressure throughout operation.
2Measurement precision
If gas pressure control systems are designed to adapt to dynamic engine operation, then precise fuel gas metering is achieved, but the systems become comparatively complex and costly
Solution Approach 1:
The patent replaces complex mechanical pressure control systems with an electronically regulated metering valve that uses electronic sensing and control to achieve precise gas metering. This substitution of mechanical complexity with electronic control reduces overall system complexity while maintaining or improving measurement precision for fuel gas delivery.
Solution Approach 2:
The electronically regulated metering valve serves multiple functions: it controls gas flow rate, adjusts pressure according to engine load, and adapts to varying operating conditions all through a single integrated component. This multi-functionality eliminates the need for separate mechanical pressure control devices, thereby reducing system complexity while achieving precise metering.
3Volume of moving object
If small flow cross sections are used in gas injection valves, then the valve size is reduced, but a high feed pressure of about 8 bar is necessary to produce full load, which limits how empty the gas tank can be
Solution Approach 1:
The patent replaces the reliance on high mechanical feed pressure with an electronically regulated metering valve that uses electronic control to achieve the required gas flow rates. This allows the use of smaller flow cross sections without requiring high tank pressure, because the electronic regulation compensates for the reduced flow area by precisely controlling the timing and duration of gas delivery.
Solution Approach 2:
The system changes the operational parameters by using electronic pulse-width modulation or similar control techniques to deliver the precise amount of gas needed through smaller valve cross sections. This allows the gas tank pressure to be reduced to lower levels while still achieving full load performance through optimized control parameters rather than relying on high static 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
Enables precise and cost-effective gas metering, improving vehicle range by allowing the gas tank to be emptied further while ensuring reliable engine operation and reducing emissions through enhanced pressure regulation and compensation for ambient pressure variations.
Implementation Method 1
The metering unit has a gas pressure regulator and a fuel gas metering valve, which is regulated, preferably electrically regulated
Implementation Method 2
the gas pressure regulator has a primary pressure regulator and a main pressure regulator downstream of the primary pressure regulator in the flow direction of the combustible gas through the metering unit
Implementation Method 3
compensation elements to adapt to varying conditions
Data Source
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AI summary
The invention relates to a metering unit (40) for a gas engine, which is connected to a gas tank on the inlet side and to a mixture formation device (70) in an intake tract (12) of the gas engine on the outlet side. The metering unit (40) has a gas pressure regulator (42) and a fuel gas metering valve (60), via which the quantity of gas supplied to the mixture-forming device (70) is regulated. The control range of the fuel gas metering valve (60) can be significantly reduced by the upstream gas pressure regulator, which means that metering of the fuel gas is easier and more precise. The invention also relates to an internal combustion engine (10) which is operated with a combustible gas and has such a metering unit (40) arranged on its intake tract (12), and a method for controlling the pressure in such a metering unit (40).