Internal Combustion Engine Drag Torque Reduction During Coasting
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Solution Overview
Problem
Existing coasting methods for motor vehicles with internal combustion engines face challenges in achieving fuel efficiency while ensuring power to auxiliary units and minimizing drag power loss.
Innovation Solution
The method involves towing the engine in unfired operation with the drive train engaged, reducing engine drag torque and power through means such as a locking device or deactivating the cylinder valve train, allowing the engine to rotate with reduced resistance and supply auxiliary units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is completely shut down during coasting to maximize fuel savings, then fuel consumption is reduced, but auxiliary units (generator, air conditioning compressor, air compressor, power steering pump) are no longer supplied with power
Solution Approach 1:
The engine operating state is changed from fired to unfired operation during coasting, maintaining rotation to drive auxiliary units while interrupting fuel supply to minimize energy consumption. This parameter change allows the engine to provide mechanical power without combustion.
Solution Approach 2:
The fuel supply is extracted or removed from the engine operation during coasting, separating the fuel combustion function from the mechanical power generation function. The engine continues to rotate and drive auxiliaries through vehicle motion alone.
2Reliability
If the engine is towed in unfired operation with drive train closed to maintain power to auxiliaries, then auxiliary units are supplied with power, but drag power loss increases due to friction losses
Solution Approach 1:
The valve train state is changed during unfired operation to reduce compression work. By deactivating the valve train or locking the piston at bottom dead center, the compression and expansion processes are minimized, significantly reducing the drag torque that opposes engine rotation during coasting.
Solution Approach 2:
The valve train function is extracted or deactivated during coasting operation, removing the source of compression resistance. This allows the engine to rotate with minimal mechanical resistance while still driving auxiliary units.
3Speed
If the drive train is disconnected during coasting to reduce engine drag torque, then coasting speed is maintained, but the engine cannot supply power to auxiliary units
Solution Approach 1:
The engine operation mode is locally changed to unfired operation, creating a specific operating condition where the engine rotates without combustion. This allows the engine to provide power to auxiliaries through vehicle motion alone, without requiring drive train disconnection.
Solution Approach 2:
The continuous rotation of the engine during coasting is maintained to ensure uninterrupted power supply to auxiliary units. By reducing drag torque through valve train deactivation rather than disconnecting the drive train, the engine continues to rotate smoothly and drive auxiliaries throughout the coasting phase.
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 reduces friction losses, maintains higher coasting speed, extends coasting distance, and ensures power to auxiliary units, thereby enhancing fuel efficiency.
Implementation Method 1
reduces friction losses, maintains higher coasting speed
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a method for the rolling operation of a motor vehicle with an internal combustion engine, in particular a commercial vehicle, wherein in rolling operation the internal combustion engine is towed in unfired operation and with the drivetrain closed, and wherein means are provided for reducing the engine drag power of the internal combustion engine, by means of which the engine drag power is reduced during rolling operation, so that the internal combustion engine is towed in rolling operation with the reduced engine drag power.