Belt Starter-Generator Torque Timing for Faster Engine Restart
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Solution Overview
Problem
Conventional restart standby control methods for internal-combustion engines, which apply preliminary powering torque to the engine via a motor generator connected via a belt transmission mechanism, lead to increased engine revolution speed resonance time, prolonged engine shutdown time, and energy wastage, while also deteriorating noise and vibration characteristics.
Innovation Solution
The method involves controlling the preliminary powering torque to be higher in the low-tension period and zero in the high-tension period of the belt's periodic tension variation, ensuring that preliminary powering is only applied when the belt tension is low, thereby avoiding unnecessary torque application during high-tension periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If preliminary powering torque is applied continuously to remove belt slack, then start responsiveness is improved, but engine revolution speed resonance time increases and noise/vibration characteristics deteriorate
Solution Approach 1:
The patent applies periodic action by controlling the motor generator to apply preliminary powering torque only during low-tension periods of the belt, rather than continuously. The controller detects belt tension periodicity and timing, and restricts torque application to specific low-tension intervals, thereby removing belt slack while minimizing resonance and noise.
Solution Approach 2:
The patent implements dynamics by making the preliminary powering torque application conditional and time-variable rather than static and continuous. The controller dynamically adjusts torque application based on real-time detection of belt tension state, engine revolution speed, and crankshaft position, applying torque only when conditions are favorable (low-tension periods).
2Reliability
If preliminary powering torque is applied continuously, then belt slack is removed, but energy consumption increases
Solution Approach 1:
The patent reduces energy consumption by applying preliminary powering torque periodically only during low-tension periods rather than continuously. The controller calculates belt tension periodicity and timing from engine revolution speed and crankshaft position, and restricts motor generator torque application to these specific intervals, thereby maintaining belt slack removal effectiveness while minimizing energy waste.
Solution Approach 2:
The patent applies partial action by providing preliminary powering torque only when and where it is most needed (during low-tension periods), rather than applying full torque continuously. This partial application is sufficient to remove belt slack while significantly reducing the total energy consumption compared to continuous torque application.
3Reliability
If preliminary powering torque is applied continuously, then belt slack is removed, but engine shutdown time is prolonged
Solution Approach 1:
The patent shortens engine shutdown time by applying preliminary powering torque periodically during low-tension periods rather than continuously. This allows the engine to decelerate more quickly through the resonance region while still maintaining adequate belt tension for reliable restart, thereby reducing the overall shutdown duration while preserving reliability.
Data Source
Figure 1~2(c)
Figure 3(a)~4
Figure 5~6
AI summary
An internal-combustion engine (1) includes a belt-driven starter generator (4), and makes an idling stop while a vehicle is at a stop. In the process of the engine revolution speed decreasing with cutting of fuel to stop the vehicle, to suppress the reduction in restart responsiveness caused by slack in a belt (9), preliminary powering of the starter generator (4) is performed. The belt tension during deceleration microscopically changes periodically between a relatively high-tension period and a relatively low-tension period due to pulsation of the engine revolution speed. Slack in the belt (9) does not occur in the high tension period, and thus preliminary powering torque is applied only in the low-tension period.