Clutch Torque Control for Engine Start Speed Gradient
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Solution Overview
Problem
The rapid rotation of heat engines during starting can lead to premature wear and damage due to excessive engine speed gradients, particularly affecting the crankshaft and oil pump, with existing control methods failing to provide sufficient precision and reproducibility in torque transmission, resulting in unacceptable speed gradient uncertainties.
Innovation Solution
A method for controlling the clutch between a high-performance electric machine and a heat engine, where the clutch is initially rotated in neutral to prevent torque transmission, then closed to transmit torque based on a predetermined maximum setpoint torque estimated for friction losses, with real-time adjustments made to the torque based on measured acceleration to achieve a target engine speed gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clutch is controlled at maximum transmissible torque to achieve high starting performance, then the start-up time is reduced, but the engine speed gradient becomes uncontrolled leading to premature wear and damage
Solution Approach 1:
The control unit continuously monitors the actual engine speed gradient during start-up and compares it to the target gradient. Based on this feedback, the control unit dynamically adjusts the clutch torque transmission to maintain the speed gradient within acceptable limits, preventing both excessive wear and suboptimal start-up performance
Solution Approach 2:
The clutch control system transitions from static maximum torque transmission to dynamic torque adjustment. The system adapts the torque transmission in real-time based on measured engine speed gradient, allowing optimal start-up performance while protecting engine components from damage
2Speed
If the clutch transmits high torque to achieve rapid engine acceleration, then starting performance is improved, but manufacturing variations and operating conditions result in insufficient precision in speed gradient control
Solution Approach 1:
The system measures the actual engine speed gradient in real-time and uses this measurement to adjust the clutch torque transmission. This closed-loop feedback compensates for manufacturing variations and operating condition changes, achieving precise speed gradient control despite these uncertainties
Solution Approach 2:
The control system dynamically changes the clutch torque parameter based on measured speed gradient deviations. By adjusting the torque transmission parameter in response to actual conditions, the system maintains precise control over engine acceleration rate
Data Source
Figure 1~2
AI summary
The invention relates to a method for controlling, when a combustion engine (7) starts, a clutch (3) that couples a high-performance electric machine (2) to the engine (7), the clutch (3) being controlled according to a reference maximum torque that can be transmitted to the engine (7) that is predetermined according to an estimate of the friction losses of the engine (7), so as to obtain a given engine (7) speed gradient. A step of measuring or estimating an acceleration of the engine speed during the transmission of the reference torque is performed and when this measured or estimated acceleration returns a difference, in relation to the given speed gradient, of more than 6.66 revolutions per second squared, at least one step of correcting the reference maximum torque on the basis of the measured or detected acceleration is performed so that the acceleration actually obtained during the start-up phase tends towards the given speed gradient.