Engine EGR Control Valve Timing Prediction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control systems for internal combustion engines face challenges in accurately adjusting the EGR rate within cylinders due to delays in the operation of variable valve timing mechanisms, leading to potential overshooting or undershooting of the target EGR rate, which can worsen driveability.
Innovation Solution
A control apparatus with EGR rate predicting means and a valve timing control device that adjusts the internal EGR gas quantity based on predictions to ensure the EGR rate within the cylinder accurately follows the target rate, incorporating an EGR control valve and a variably operated valve mechanism to manage valve timing and overlap quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the variable valve timing mechanism is used to increase the internal EGR to compensate for insufficient external EGR, then the EGR rate within the cylinder can be maintained at target values during transient switching, but the EGR rate may overshoot or undershoot the target value due to operation delay of the variable valve timing mechanism
Solution Approach 1:
The control device predicts the EGR rate variation that will occur due to valve timing modification before actually executing the valve timing change. By calculating the predicted EGR rate in advance and using it to determine the appropriate valve timing adjustment, the system compensates for the inherent delay in the variable valve timing mechanism's response, preventing overshoot or undershoot of the target EGR rate
Solution Approach 2:
The control device continuously monitors the actual EGR rate and compares it with the target EGR rate. Based on this feedback and the predicted EGR rate variation, the control device dynamically adjusts the valve timing to maintain accurate EGR rate control, correcting for the response delay of the variable valve timing mechanism
2Quantity of substance
If the valve timing is modified to increase internal EGR, then the insufficient external EGR can be compensated, but the driveability may worsen due to inaccurate EGR rate control
Solution Approach 1:
By predicting the EGR rate variation before executing valve timing modification, the control device can determine the precise amount of valve timing change needed to achieve the target EGR rate. This preliminary calculation ensures accurate EGR rate control while maintaining smooth transient response, thereby preserving driveability during EGR rate transitions
Data Source
AI summary
In a case where a driving state is switched from a high load to a low load in a non-turbo charge region and an external EGR is stopped, at a timing T01 at which an EGR control valve (21) is closed, a valve overlap quantity between an intake valve and an exhaust valve is, as a low load transient time provisional value, controlled in a direction such that the valve overlap between the intake and exhaust valves is once contracted. Then, a target value of the valve overlap quantity between the intake and exhaust valves at a timing T21 preceded by a response time Δt of the variably operated valve mechanism (28) from a timing T31 at which the opening angle of the EGR control valve (21) is modified from the low load transient time provisional value to the target value at the time of the low load.