Dynamic Torque Reserve for Engine Start
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Solution Overview
Problem
Internal combustion engines face challenges in starting efficiently due to the limited torque capacity of electric machines, which can result in reduced vehicle energy efficiency and noticeable propulsion torque reduction when restarting the engine, or increased energy consumption when using a small portion of the electric machine's torque capacity.
Innovation Solution
A method for dynamically adjusting the torque reserve of an electric machine based on the engine's stopping position and the expected reduction in cranking torque from combustion in cylinders on expansion and compression strokes, allowing the engine to start when driver demand torque exceeds the available torque minus the torque reserve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric machine uses maximum torque capacity to start the engine, then the engine starting reliability is improved, but the vehicle propulsion torque is reduced noticeably
Solution Approach 1:
The patent applies dynamics by making the torque reserve adjustable rather than fixed. The controller dynamically modifies the torque reserve amount based on real-time vehicle operating conditions, including driver demand torque, battery state of charge, and vehicle speed. This dynamic adjustment allows the system to optimize the balance between ensuring sufficient torque for engine starting and maintaining adequate propulsion torque for vehicle performance.
2Object-generated harmful factors
If the electric machine uses a small portion of torque capacity to start the engine, then the propulsion torque is maintained, but the energy consumption increases
Solution Approach 1:
The patent applies parameter changes by modifying the torque reserve parameter based on multiple operating conditions. The controller adjusts the torque reserve amount according to driver demand torque, battery state of charge, vehicle speed, and engine cranking speed. This parameter adjustment optimizes energy utilization by ensuring the electric machine operates efficiently across different operating scenarios.
3Reliability
If the torque reserve is increased to ensure engine starting, then the engine starting capability is improved, but the available torque for vehicle propulsion is reduced
Solution Approach 1:
The patent applies feedback by continuously monitoring vehicle operating conditions and adjusting the torque reserve accordingly. The controller receives feedback from sensors measuring driver demand torque, battery state of charge, vehicle speed, and engine cranking speed. This feedback loop enables real-time optimization of torque allocation, ensuring sufficient torque reserve for engine starting while maintaining adequate propulsion torque based on actual vehicle needs.
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 sufficient torque for engine starting, improves vehicle energy efficiency by utilizing a greater portion of the electric machine's torque capacity, and reduces energy consumption during engine starting.
Implementation Method 1
one or more electric machines that may provide torque to a driveline
Implementation Method 2
an expected amount of reduction in required cranking torque due to the torque and work generated from combustion in cylinders initially positioned on expansion and compression strokes
Data Source
AI summary
A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes starting an engine via expansion stroke combustion in response to a request to urgently start the engine. In addition, the method includes adjusting a position of a compression relief valve in response to a predicted urgency of an engine start.