Hybrid Drivetrain Clutch Control for Fast, Low-Vibration Decoupling
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Solution Overview
Problem
The abrupt disengagement of the separating clutch between the internal combustion engine and the electric machine in hybrid vehicles can cause discomfort due to strong engine run-up, noise, and vibrations, necessitating a method to decouple the engine quickly and comfortably.
Innovation Solution
The method involves determining the absolute torque transmitted by the separating clutch and disengaging it at different rates, using stepwise or torque-controlled disengagement at varying speeds, and controlling the internal combustion engine's rotational speed to manage torque and differential speed gradients, ensuring comfortable and rapid decoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the separating clutch is abruptly disengaged to quickly decouple the internal combustion engine, then the decoupling speed is improved, but noise and vibrations increase causing discomfort
Solution Approach 1:
The separating clutch disengagement is made dynamic by adjusting the disengagement rate based on real-time torque conditions. The control system monitors the absolute torque value and dynamically selects between fast disengagement (when torque is low) and controlled disengagement (when torque is high), optimizing both speed and comfort based on operating conditions.
Solution Approach 2:
The disengagement rate parameter of the separating clutch is changed based on torque conditions. When absolute torque exceeds a threshold, the disengagement rate is reduced and a torque gradient is imposed to limit the rate of torque change, thereby reducing noise and vibrations while still achieving decoupling.
2Object-affected harmful factors
If the separating clutch is disengaged slowly to reduce noise and vibrations, then comfort is improved, but the decoupling time increases
Solution Approach 1:
The control system dynamically adjusts the disengagement strategy based on real-time torque monitoring. When torque is low, fast disengagement is permitted; when torque is high, the system transitions to a controlled disengagement mode, optimizing the balance between speed and comfort for each moment of the decoupling process.
Solution Approach 2:
The disengagement process is divided into different phases or periods based on torque conditions. The system transitions between fast disengagement phase (when torque < threshold) and controlled disengagement phase (when torque >= threshold), creating a periodic or staged action that optimizes both time and comfort.
3Object-affected harmful factors
If the separating clutch is disengaged with a torque gradient to reduce vibrations, then comfort is improved, but the disengagement rate decreases
Solution Approach 1:
The disengagement rate parameter is changed based on torque conditions. The control system imposes a maximum torque gradient limit during disengagement when torque is high, which controls the rate of torque change and thereby reduces vibrations, while accepting a slower disengagement rate during this controlled phase.
Data Source
AI summary
A method for operating a drive train of a motor vehicle with a prime mover (1) including an internal combustion engine (2) and an electric machine (3), a separating clutch (6) connected between the internal combustion engine and the electric machine, and a transmission (5) connected between the prime mover (1) and a driven end (4) is provided. When at least one first operating condition is present, a previously decoupled internal combustion engine (2) is coupled such that the separating clutch (6) is actuated to engage. When at least one second operating condition is present, the coupling of the internal combustion engine is aborted, and an absolute value of a torque currently transmitted or currently transmittable by the separating clutch (6) is determined. The separating clutch (6) is disengaged at different rates depending on the absolute value of the torque currently transmitted or currently transmittable by the separating clutch (6).