Intake Efficiency Estimation via Overlap Flow Calculation
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Solution Overview
Problem
Existing methods for determining the air mass trapped in each cylinder of an internal combustion engine are inaccurate and costly, especially in engines with Variable Valve Height (VVH) and Variable Valve Timing (VVT) control techniques, as they rely on expensive air flow meters that can be fouled by oil vapors and dust.
Innovation Solution
A method calculates the mass of the overlap gaseous flow (MOVL) based on hydraulic permeability, compression factors, and temperature ratios, using the relation MOVL=PERM*β(P/P0,n)*P0/P0_REF*(T0_REF/T0)1/2/n, where PERM is hydraulic permeability, β is a compression factor, and P and T are pressures and temperatures, allowing for controlled variation of intake and exhaust valve lift to estimate air mass without an air flow meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air flow meter is used to detect the flow rate of fresh air, then the measurement of air mass trapped in each cylinder is obtained, but the cost increases and the component becomes delicate and prone to fouling by oil vapors and dust
Solution Approach 1:
The invention extracts the measurement function from the expensive air flow meter and implements it through a calculation method using readily available sensor data (intake manifold pressure, exhaust manifold pressure, engine speed, valve timing). This removes the need for the delicate air flow meter while maintaining measurement capability through mathematical modeling of the gas flow through valves during overlap conditions.
Solution Approach 2:
Instead of directly measuring air flow with expensive hardware, the invention creates a computational model that replicates the measurement function using data from existing, cheaper sensors. The calculation method copies the essential measurement capability through software algorithms rather than physical measurement devices.
2Adaptability or versatility
If Variable Valve Height (VVH) and Variable Valve Timing (VVT) control techniques are applied to improve engine performance, then the control flexibility and efficiency are enhanced, but the accuracy of air mass determination methods becomes insufficient with existing approaches
Solution Approach 1:
The invention dynamically adapts the calculation model to account for variable valve lift and timing conditions. The hydraulic permeability coefficient and overlap duration are continuously adjusted based on actual valve positions and timing, allowing accurate air mass determination across the full range of VVH and VVT operating conditions rather than relying on fixed parameters.
Solution Approach 2:
The invention changes the approach from using fixed measurement parameters to dynamically adjusting calculation parameters (hydraulic permeability, overlap duration, compression factor) based on actual valve timing and lift conditions. This allows the system to maintain measurement accuracy across varying operational modes enabled by VVH and VVT technologies.
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 method provides accurate air mass estimation with high precision, reducing the need for expensive sensors and maintaining performance in VVH and VVT engine control systems, achieving an estimation accuracy below 3% absolute error compared to engine bench measurements.
Implementation Method 1
PERM is the hydraulic permeability associated to the overlap condition
Implementation Method 2
β(P/P0,n) is a compression factor of a flow through an orifice, depending on the ratio between the pressures downstream and upstream of the orifice
Data Source
AI summary
A method for calculating the mass of an overlap gaseous flow (MOVL), wherein the exhaust pressure is higher than the intake pressure, or in the case of scavenging (SCAV), wherein the intake pressure is higher than the exhaust pressure. The overlap gaseous flow (MOVL) is the flow which flows, in overlap conditions, through the intake valve and the exhaust valve of a cylinder of an internal combustion engine. At least one intake valve is driven so as to vary the lift (H) of the intake valve in controlled manner. The overlap condition is a condition in which the intake valve and the exhaust valve are both at least partially open. The method comprises calculating the mass of the gaseous flow (MOVL) which flows through the intake valve and the exhaust valve on the basis of the relation:MOVL=PERM*β(P/P0,n)*P0/P0_REF*(T0_REF/T0)1/2/n.