Belt-Driven Starter Generator Torque Amplification
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Solution Overview
Problem
Existing belt-driven starter generators for internal combustion engines are large, heavy, and expensive due to the need for powerful torque to overcome breakaway and compression torques, necessitating a method to enhance output torque on the crankshaft without increasing the size or weight of the starter generator.
Innovation Solution
A method that predefines a drive torque curve for the starter generator, allowing output torque on the crankshaft to exceed the transmitted torque by up to 60% by utilizing the dynamic properties of the belt drive, with the torque curve defined in relation to the first natural frequency or period of the belt drive, enabling efficient breakaway torque overcoming with a smaller peak torque starter generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a powerful starter generator is used to overcome breakaway torque, then the engine can be started reliably, but the starter generator becomes large, heavy, and expensive
Solution Approach 1:
The patent applies dynamics by using a predefined torque curve that varies the drive torque over time during the starting process. The torque is increased from zero to a maximum value and then reduced, utilizing the dynamic characteristics of the belt drive system to achieve torque amplification. This allows a smaller starter generator to produce sufficient breakaway torque through dynamic torque modulation rather than requiring constant high torque capability.
Solution Approach 2:
The patent utilizes mechanical vibration by defining the torque curve in relation to the natural frequency of the belt drive. The acceleration duration is set to correspond to at most double, single, or half the first natural period duration, which excites resonant vibrations in the belt drive system. This resonance amplifies the torque transmission, enabling a smaller starter generator to overcome breakaway torque effectively.
2Reliability
If a powerful starter generator is used to overcome breakaway torque, then the engine can be started reliably, but the starter generator becomes large and expensive
Solution Approach 1:
The patent applies dynamics by using a predefined torque curve that varies the drive torque over time during the starting process. The torque is increased from zero to a maximum value and then reduced, utilizing the dynamic characteristics of the belt drive system to achieve torque amplification. This allows a smaller starter generator to produce sufficient breakaway torque through dynamic torque modulation rather than requiring constant high torque capability.
Solution Approach 2:
The patent utilizes mechanical vibration by defining the torque curve in relation to the natural frequency of the belt drive. The acceleration duration is set to correspond to at most double, single, or half the first natural period duration, which excites resonant vibrations in the belt drive system. This resonance amplifies the torque transmission, enabling a smaller starter generator to overcome breakaway torque effectively.
3Speed
If the starter generator accelerates the crankshaft quickly, then the starting process is faster, but the torque required to overcome static friction increases
Solution Approach 1:
The patent applies preliminary action by gradually increasing the drive torque from zero to the maximum value according to a predefined torque curve, rather than applying maximum torque immediately. This gradual acceleration allows the belt drive system to build up elastic energy and utilize resonance, which amplifies the torque at critical moments to overcome breakaway torque effectively while maintaining controlled crankshaft acceleration.
Solution Approach 2:
The patent utilizes mechanical vibration by defining the torque curve in relation to the natural frequency of the belt drive. The acceleration duration is set to correspond to at most double, single, or half the first natural period duration, which excites resonant vibrations in the belt drive system. This resonance amplifies the torque transmission, enabling a smaller starter generator to overcome breakaway torque effectively.
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 effective engine starting with a smaller, lighter, and less costly starter generator by increasing output torque on the crankshaft beyond the transmitted peak torque, overcoming breakaway torque and saving space, weight, and cost while maintaining a low-noise and low-vibration starting process.
Implementation Method 1
the output torque temporarily exceeding the transmitted (i.e., taking the gear ratio of the belt drive into consideration) drive torque of the starter generator
Implementation Method 2
predefined as a function of the first natural frequency or the first natural period duration of the belt drive
Data Source
AI summary
A method for starting an internal combustion engine using a starter generator to which the engine is connected via a belt drive, the belt drive including a belt pulley of the starter generator, a belt pulley of the internal combustion engine, and a belt connecting the belt pulleys in a torque-transmitting manner, includes operating the starter generator such that its drive torque output to the belt pulley of the starter generator is according to a drive torque curve by which an output torque generated temporarily on the belt pulley of the internal combustion engine exceeds the drive torque of the starter generator, taking a gear ratio of the belt drive into consideration.