Hybrid Torque Control for Cold Start Emission Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hybrid vehicles face challenges in reducing driver-specific and start process-specific effects on exhaust gas emissions during cold starts, as the exhaust gas emission control system may not be operational, leading to varying raw emissions due to non-reproducible driver behaviors and load conditions.
Innovation Solution
A method for controlling the drive torque of a hybrid vehicle by determining a torque difference between a predetermined nominal torque and the actual desired torque, with the electric machine operating in motor-mode to supplement the internal combustion engine when the desired torque exceeds the nominal torque, and in generator-mode to charge the energy store when the desired torque is lower, ensuring the internal combustion engine operates optimally for low emissions and quick emission control system activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the internal combustion engine operates according to actual driver-requested torque during cold start, then the vehicle can respond to driver load demands, but the exhaust gas emissions become non-reproducible and may exceed limits due to driver-specific variations
Solution Approach 1:
The torque provision is segmented between two sources: the internal combustion engine provides a predetermined nominal torque optimized for emissions, while the electric machine supplements the remaining torque difference. This segmentation allows the combustion engine to operate in a reproducible, emission-optimized mode while still meeting total torque demands.
Solution Approach 2:
The electric machine acts as an intermediary that bridges the gap between the predetermined nominal torque from the combustion engine and the actual driver-requested torque. By providing or absorbing the torque difference, the electric machine enables the combustion engine to maintain its optimized operating point without directly responding to driver variations.
2Reliability
If the internal combustion engine is optimized for quick emission control system activation, then the catalytic converter reaches operational readiness faster, but the engine cannot adapt to varying driver torque requirements
Solution Approach 1:
The system performs preliminary action by pre-defining the optimal torque curve for the internal combustion engine that maximizes emission control system heating and activation. This predetermined nominal torque is calculated in advance based on emission optimization criteria, allowing the catalytic converter to reach light-off temperature as quickly as possible.
Solution Approach 2:
The system changes the operating parameters of the internal combustion engine from driver-requested values to predetermined optimized values during cold start. By adjusting the torque parameter to match the predetermined nominal torque, the engine operates in a specific regime that prioritizes emission control system activation while the electric machine compensates for any torque shortfall.
3Object-generated harmful factors
If a predetermined nominal torque is used for the internal combustion engine during cold start, then emissions become reproducible and optimized, but additional complexity is introduced in torque management
Solution Approach 1:
The electric machine serves multiple functions: it supplements torque when the combustion engine operates at predetermined nominal torque, it can absorb excess torque when the predetermined torque exceeds driver demand, and it provides starting assistance. This multi-functionality allows the system to use a simple predetermined torque strategy without requiring complex additional control mechanisms.
Solution Approach 2:
The control system continuously monitors the torque difference between the predetermined nominal torque and the actual driver-requested torque, and adjusts the electric machine's torque contribution accordingly. This feedback mechanism ensures that the total torque delivered to the wheels matches driver demand while the combustion engine maintains its optimized operating point.
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 allows for reproducible optimization of the internal combustion engine operation during starts, reducing overall exhaust gas emissions by maintaining optimal emission control system readiness and minimizing raw emissions, independent of driver-specific and start process variations.
Implementation Method 1
an electric machine, which can be operated either in motor-mode or in generator-mode. The electric machine provides in motor-mode an electromotive torque, which in conjunction with a torque of the first drive source represents a total drive torque of the drive unit, and which in generator-mode supplies electric power
Data Source
AI summary
The invention is directed to a method and a system for controlling a drive torque of a hybrid drive unit (10) of an automobile after a start. The hybrid drive unit (10) includes a first drive source (12), in particular an internal combustion engine, includes at least one electric machine (14), which can be operated either in motor-mode or in generator-mode, wherein the electric machine (14) provides in motor operation an electromotive torque (M_EM), which in conjunction with a torque (M_VM) of the first drive source (12) represents a total drive torque of the drive unit (10), and supplies in generator-mode electric power.