Hybrid Catalyst Warm-Up via Waste Gate Valve Control
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Solution Overview
Problem
In hybrid vehicles, the catalyst used to purify exhaust gases is often unevenly activated due to variations in exhaust flow rates, leading to reduced purification performance, especially at low temperatures when the engine starts.
Innovation Solution
A hybrid vehicle system that includes a turbocharger, a catalyst in the exhaust passage downstream of the turbine, a bypass passage, a waste gate valve, and a controller for warm-up control, which performs two processing stages: first processing with a low exhaust flow rate to uniformly activate the catalyst and second processing with increased flow rate to ensure complete catalyst activation and efficient purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the internal combustion engine is activated to warm up the catalyst, then the catalyst temperature increases and activation is promoted, but exhaust purification performance deteriorates due to uneven catalyst activation
Solution Approach 1:
The patent applies local quality by creating different exhaust flow conditions in different regions of the catalyst. By controlling the waste gate valve to regulate exhaust flow, the system ensures that exhaust evenly distributes across the entire upstream-side end surface of the catalyst, promoting uniform activation throughout the catalyst rather than localized heating. This resolves the contradiction by making the temperature distribution more homogeneous while maintaining purification performance.
Solution Approach 2:
The patent uses dynamic control of the waste gate valve to adjust exhaust flow rates during the warm-up process. The controller dynamically regulates the valve opening based on engine operating conditions and catalyst temperature, optimizing the balance between warming up the catalyst and maintaining purification performance. This dynamic adjustment prevents both overheating and insufficient activation, resolving the contradiction between temperature increase and performance maintenance.
2Productivity
If exhaust flow rate is high during catalyst warm-up, then warm-up speed increases, but uneven activation occurs due to localized exhaust flow
Solution Approach 1:
The patent addresses activation uniformity by ensuring exhaust flow distributes evenly across different regions of the catalyst upstream end surface. The waste gate valve control system adjusts local flow characteristics to prevent concentration of exhaust in specific areas, thereby achieving uniform activation throughout the catalyst while maintaining efficient warm-up speed.
Solution Approach 2:
The controller uses feedback from temperature sensors and engine operating conditions to dynamically adjust the waste gate valve position. This feedback mechanism allows the system to monitor catalyst temperature distribution and adjust exhaust flow accordingly, preventing localized overheating while maintaining overall warm-up efficiency. The closed-loop control ensures both speed and uniformity of activation.
3Duration of action of stationary object
If the waste gate valve is fully opened to increase exhaust flow, then catalyst warm-up is accelerated, but exhaust purification performance drops due to catalyst deactivation
Solution Approach 1:
The patent applies dynamic control to the waste gate valve, adjusting its opening degree based on real-time catalyst temperature and engine operating conditions. Rather than maintaining a fixed fully-open position, the controller dynamically modulates the valve to optimize the balance between warm-up speed and purification performance. This prevents catalyst deactivation by maintaining appropriate flow rates while accelerating warm-up when conditions permit.
Solution Approach 2:
The system changes the operational parameters of the waste gate valve (opening degree, position) based on catalyst temperature and engine load. By dynamically adjusting these parameters, the system optimizes exhaust flow rates to achieve rapid warm-up without causing catalyst deactivation. The parameter changes allow the system to adapt to different operating conditions while maintaining both warm-up efficiency and purification performance.
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 approach ensures uniform catalyst activation and maintains high exhaust purification performance by optimizing the warm-up process, reducing the time required for catalyst activation and minimizing deterioration in drivability.
Implementation Method 1
a catalyst that purifies exhaust
Implementation Method 2
a waste gate valve that regulates a flow rate of exhaust that flows through the bypass passage
Implementation Method 3
a turbocharger, a catalyst that purifies exhaust, the catalyst being provided in an exhaust passage downstream from a turbine of the turbocharger
Data Source
AI summary
When it is determined that control of warm-up of a catalyst is necessary at the time of start of an engine, an ECU starts warm-up control. Initially, the ECU performs first processing for a first set time period. In the first processing, the ECU sets the engine to an idle state and fully opens a waste gate valve. When the first set time period has elapsed since the first processing was started, the ECU performs second processing. In the second processing, the ECU sets the engine to a prescribed rotation speed and fully closes the waste gate valve. When a second set time period has elapsed since the second processing was started, the ECU quits the second processing and quits warm-up control.