Powertrain Shift Control Under Catalyst Temperature Limits
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Solution Overview
Problem
Existing power train control systems face challenges in maintaining a theoretical air-fuel ratio over the entire engine operation range while preventing thermal deterioration of the three-way catalyst and ensuring adequate vehicle performance, particularly when the intake air charge amount is limited to avoid excessive catalyst temperature.
Innovation Solution
A power train control device that includes an engine control unit for maintaining a theoretical air-fuel ratio and limiting intake air charge, and a transmission control unit for forced up-shifts and revolution limit changes to balance catalyst temperature and engine output, using sensors and control modules to adjust engine and transmission operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire range theoretical air-fuel ratio operation is performed to achieve high emission performance, then the purification rate of the three-way catalyst is improved, but the temperature of the three-way catalyst exceeds the allowable temperature causing thermal deterioration
Solution Approach 1:
The invention changes the control parameter from throttle opening degree to intake air charge amount. By directly controlling the intake air charge amount rather than indirectly through throttle valve, the system can precisely regulate the amount of air entering the engine, thereby controlling combustion heat and exhaust gas temperature to prevent catalyst overheating while maintaining theoretical air-fuel ratio operation for high emission performance
Solution Approach 2:
The invention implements feedback control by monitoring the actual intake air charge amount and comparing it with the target value. The system adjusts the intake air charge amount based on this feedback to maintain it within a range that prevents catalyst temperature from exceeding the allowable limit, while ensuring theoretical air-fuel ratio operation is maintained for optimal emission performance
2Temperature
If the intake air charge amount is limited to prevent catalyst temperature from exceeding the allowable temperature, then the thermal deterioration of the three-way catalyst is prevented, but the output from the engine becomes insufficient causing poor driving performance
Solution Approach 1:
The invention dynamically adjusts the intake air charge amount limit based on engine operating conditions. The control unit sets different upper limit values for intake air charge amount according to engine revolution speed and load, allowing the engine to operate at higher power outputs when catalyst temperature is low, while preventing overheating when temperature approaches the allowable limit. This dynamic control maintains both catalyst protection and driving performance
3Temperature
If the throttle opening degree is regulated to control catalyst temperature, then the temperature of the three-way catalyst is prevented from exceeding the allowable temperature, but the intake air charge amount becomes lower than required causing insufficient vehicle speed increase
Solution Approach 1:
The invention extracts the temperature control function from the throttle valve control system. Instead of using the throttle valve to control both air charge and temperature, the system separately controls intake air charge amount to manage temperature, while the throttle valve focuses on controlling engine load and power output. This separation allows independent optimization of both catalyst temperature protection and vehicle speed response
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
The system enables advanced emission performance by maintaining catalyst temperature within limits while preventing a reduction in vehicle speed and output, ensuring stable driving performance.
Implementation Method 1
an exhaust gas purification apparatus that purifies, using a three-way catalyst, exhaust gas exhausted from the engine
Implementation Method 2
it is possible to reduce the amount of heat in exhaust gas by making use of heat of vaporization of fuel
Data Source
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AI summary
Provided is a power train control device 10 for a vehicle including an exhaust gas purification apparatus 52 and an automatic transmission 3, the vehicle traveling by controlling an engine 2 and the automatic transmission 3. The power train control device 10 includes an ECM 11 and a TCM 12. The ECM 11 performs entire range theoretical air-fuel ratio operation control, and also performs intake air charge amount limit control when an intake air charge amount reaches an upper limit value that is set to prevent a temperature of a three-way catalyst from exceeding an allowable temperature. The TCM 12 performs automatic shift control, and performs forced up-shift control of forcibly shifting up the automatic transmission 3 when an engine revolution speed reaches a revolution limit. When the ECM 11 limits the intake air charge amount, the TCM 12 performs revolution limit change control of lowering the revolution limit.