Engine Intake Flow Estimation via Exhaust Throttle Valve
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Solution Overview
Problem
The inability to accurately estimate intake flow rate in engines without an air flow meter, particularly during forced regeneration processes, due to reduced exhaust throttle valve opening, which affects volumetric efficiency and engine control, and the high cost of air flow meters.
Innovation Solution
A control device that estimates intake flow rate using the opening degree of the exhaust throttle valve and engine operation state, without relying on an air flow sensor, by establishing relationships between intake flow rate, exhaust throttle valve opening, and engine state parameters, and includes components for PM deposition amount estimation and correction to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air flow meter is installed to accurately measure intake flow rate, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses the exhaust throttle valve opening degree as an intermediary parameter to estimate intake flow rate. Instead of directly measuring intake flow with a complex air flow meter, the system uses the exhaust throttle valve position (which is already controlled for regeneration) as a proxy indicator. The control device correlates exhaust throttle opening with intake flow rate through pre-stored maps, eliminating the need for direct intake flow measurement hardware.
Solution Approach 2:
The patent creates a virtual model of intake flow rate by using exhaust-side parameters. The control device stores maps that correlate exhaust throttle valve opening degree and engine operation state with intake flow rate characteristics. This virtual copying allows the system to estimate intake conditions based on exhaust conditions, avoiding the need for physical sensors in the intake path.
2Productivity
If the exhaust throttle valve opening degree is reduced during forced regeneration to increase DPF temperature, then PM removal effectiveness is improved, but intake flow rate estimation accuracy deteriorates
Solution Approach 1:
The patent pre-stores multiple maps that correlate exhaust throttle valve opening degree with intake flow rate characteristics under different operating conditions. Before the forced regeneration process begins, the system has already prepared the relationship data that accounts for reduced throttle openings. During regeneration, the control device simply references the appropriate pre-stored map data rather than relying on normal operating correlations, thus maintaining estimation accuracy despite the abnormal throttle position.
Solution Approach 2:
The patent dynamically adapts the estimation approach by switching between different pre-stored maps based on operational mode. The control device selects appropriate correlation data from multiple pre-stored maps that correspond to different exhaust throttle opening conditions. This dynamic selection allows the system to maintain accurate intake flow rate estimation whether the exhaust throttle is fully open during normal operation or partially closed during forced regeneration.
3Productivity
If late-post injection is used to increase DOC temperature for DPF regeneration, then regeneration capability is improved, but control complexity increases
Solution Approach 1:
The patent combines the exhaust throttle valve control function with the temperature increase function for DPF regeneration. Instead of using a separate late-post injection strategy to raise DOC temperature, the system utilizes the exhaust throttle valve (already present in the exhaust system) to create backpressure and increase exhaust gas temperature. This merging of functions eliminates the need for complex multi-stage injection control while achieving the same regeneration objective through a simpler single-control mechanism.
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 accurate estimation and control of intake flow rate during forced regeneration and normal operations, reducing reliance on air flow sensors and lowering engine costs while maintaining efficient engine performance.
Implementation Method 1
oxidizing the non-combusted fuel with the diesel oxidization catalyst (DOC) to generate heat
Implementation Method 2
the opening degree of an exhaust throttle valve disposed in an exhaust passage of the engine may be reduced
Data Source
AI summary
Provided is a control device configured to be able to execute, in an engine which includes a DOC, a DPF, and a temperature increase unit including an exhaust throttle valve, for increasing a temperature of each of the DOC and the DPF, a forced regeneration process of removing PM deposited on the DPF by increasing the temperature of the DPF. The control device includes a flow rate estimation part configured to estimate an intake flow rate of a combustion gas sent into a cylinder of the engine. The flow rate estimation part is configured to estimate a first intake flow rate, which is the intake flow rate in the forced regeneration process, from an opening degree of the exhaust throttle valve and a first state amount which indicates an operation state of the engine including a rotation speed of the engine, based on a first relationship representing a relationship between the first intake flow rate, and the opening degree of the exhaust throttle valve and the first state amount, in the forced regeneration process.