Turbocharger Control for Catalyst Warm-up in Low Pressure
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Solution Overview
Problem
In highland areas with low atmospheric pressure, existing control apparatuses for internal combustion engines with turbo-superchargers face difficulties in securing sufficient warm-up performance for exhaust gas purifying catalysts due to decreased air density, leading to challenges in maintaining required intake air amounts and retarding ignition timing, which affects energy introduction to the catalyst.
Innovation Solution
A control apparatus that utilizes two types of intake air amount control methods based on the sensitivity of the throttle valve's control, employing the throttle valve and waste gate valve to adjust intake air and ignition timing, ensuring adequate energy introduction to the catalyst by compensating for energy drops through increased ignition timing retardation when the waste gate valve is closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the throttle valve opening is enlarged to secure required intake air amount in highland area, then the intake air amount is sufficient, but the difference between intake pressures before and after the throttle valve decreases making control difficult
Solution Approach 1:
The patent divides the intake air amount control function into two separate control mechanisms: throttle valve control for normal conditions and waste gate valve control for highland areas. This segmentation allows each valve to operate in its optimal range, with the waste gate valve providing additional control authority when the throttle valve's control sensitivity becomes insufficient due to high altitude conditions.
Solution Approach 2:
The patent changes the control parameter from solely throttle valve opening degree to a combination of throttle valve opening degree and waste gate valve opening degree. By introducing the waste gate valve as an additional control parameter, the system can maintain effective control sensitivity even when the throttle valve is nearly fully open in highland areas with low atmospheric pressure.
2Temperature
If the ignition timing is retarded to increase exhaust gas temperature for catalyst warm-up, then the catalyst warm-up performance is improved, but the torque of the internal combustion engine decreases
Solution Approach 1:
The patent applies preliminary action by opening the waste gate valve before catalyst warm-up is needed, and maintaining it open during the warm-up period. This preliminary preparation of the exhaust flow path allows the system to achieve the necessary exhaust gas temperature and flow rate for effective catalyst warm-up without excessive ignition timing retard, thereby preserving engine torque.
Solution Approach 2:
The waste gate valve acts as an intermediary mechanism that mediates between the need for high exhaust gas temperature (for catalyst warm-up) and the need for sufficient engine torque. By controlling the waste gate valve opening, the system can regulate exhaust flow to achieve optimal catalyst warm-up conditions while minimizing the negative impact on engine torque that would result from excessive ignition timing retard.
3Use of energy by moving object
If the waste gate valve is closed to increase energy introduction to the catalyst, then the catalyst warm-up is enhanced, but the intake air amount control becomes difficult in highland area
Solution Approach 1:
The patent segments the control functions by assigning the waste gate valve primarily to energy introduction control (affecting catalyst warm-up) and the throttle valve to intake air amount control. This functional segmentation allows the system to independently optimize both objectives: the waste gate valve can be closed to maximize energy introduction to the catalyst while the throttle valve maintains control over intake air amount, even in highland areas.
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 configuration ensures favorable warm-up performance of the exhaust gas purifying catalyst regardless of atmospheric pressure, maintaining energy levels and reducing exhaust emissions while avoiding combustion deterioration.
Implementation Method 1
a turbo-supercharger (22) including a compressor (22a)
Implementation Method 2
a turbine (22b) that is rotated by exhaust gas
Implementation Method 3
the amount of exhaust energy that is introduced into the exhaust gas purifying catalyst can be increased
Data Source
AI summary
A control apparatus for an internal combustion engine of this invention includes: a turbo-supercharger; an exhaust gas purifying catalyst disposed in an exhaust passage on the downstream side of a turbine; and a WGV capable of opening and closing an exhaust bypass passage that bypasses the turbine. At the time of a catalyst warm-up request, catalyst warm-up control that opens the WGV and retards the ignition timing is executed. If the sensitivity of control of an intake air amount by a throttle valve is high, the intake air amount is controlled using the throttle valve during execution of the catalyst warm-up control. If the control sensitivity is low, the intake air amount is controlled using the WGV during execution of the catalyst warm-up control. When the WGV degree of opening is controlled toward a closed side during execution of the intake air amount control using the WGV, a retard amount of the ignition timing is increased.