Vehicle Drive Decoupling Control via Speed Gradient
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Solution Overview
Problem
Existing systems for controlling the coupling and decoupling of drive devices in hybrid and electric vehicles often result in untimely decoupling, leading to mechanical stress and potential damage due to overspeeding, as they rely on predefined threshold speeds that do not account for sudden changes in driver intent or environmental conditions.
Innovation Solution
A system that uses dual control mechanisms to confirm or invalidate decoupling and coupling commands based on the speed gradient of the vehicle's displacement means, with adjustable ascending and descending threshold speeds that vary according to measured parameters such as speed gradient and environmental conditions, allowing for instantaneous control of the dog clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric machine is decoupled based on predefined threshold speed to protect from overspeeding, then the mechanical protection of the drive device is improved, but the timing accuracy of decoupling deteriorates due to sudden changes in driver intent or environmental conditions
Solution Approach 1:
The patent applies dynamics by making the threshold speed variable rather than fixed. The control unit adjusts the threshold speed dynamically based on the gradient of rotational speed, allowing the decoupling decision to adapt to changing operating conditions. This resolves the contradiction by enabling timely decoupling protection while accounting for sudden changes in driver intent or environmental conditions.
Solution Approach 2:
The patent changes the parameter of threshold speed from a constant value to a variable parameter that depends on the gradient of rotational speed. By monitoring how quickly the speed is changing, the system can predict future speed values and adjust the decoupling threshold accordingly, ensuring both mechanical protection and timing accuracy.
2Reliability
If the decoupling time is extended to ensure proper disengagement, then the mechanical protection is improved, but the response time to driver intent changes deteriorates
Solution Approach 1:
The patent applies preliminary action by using the gradient of rotational speed to predict future speed values before actual overspeeding occurs. The control unit calculates the rate of change and uses this information to anticipate when decoupling will be needed, allowing the system to prepare and execute decoupling at the optimal moment rather than reacting too late.
Solution Approach 2:
The system uses feedback by continuously monitoring the rotational speed gradient and adjusting the decoupling decision based on this information. The control unit receives feedback about how quickly speed is changing and uses this to dynamically adjust the threshold, ensuring both adequate protection time and rapid response to changing conditions.
3Reliability
If the threshold speed is set low to prevent overspeeding, then the reliability of the drive device is improved, but the energy recovery capability deteriorates due to premature decoupling
Solution Approach 1:
The patent makes the threshold speed dynamic rather than static, adjusting it based on the gradient of rotational speed. This allows the system to maintain a lower effective threshold when speed is increasing rapidly (preventing overspeeding) while allowing higher speeds when the gradient indicates slower acceleration, thereby optimizing energy recovery without compromising protection.
Solution Approach 2:
The patent changes the threshold speed parameter based on the gradient of rotational speed. When the gradient is high (rapid acceleration), the threshold is effectively lowered to prevent overspeeding. When the gradient is low (slow acceleration), the threshold can be higher, allowing better energy recovery. This dynamic parameter adjustment resolves the contradiction between protection and energy efficiency.
Data Source
Figure 1~2
AI summary
This system for controlling the coupling/uncoupling of a vehicle drive device comprises at least one movement means for moving the vehicle driven by the drive device when it is in the coupled mode, an actuation means having a maximum allowable operating speed and a rising operating threshold speed (Sh), lower than said maximum speed, controlling the uncoupling of the drive device, once the uncoupling command has been sent, the control means controlling a value of the speed gradient of the movement means in order to confirm or refuse the uncoupling command. The invention also concerns an identical method and a motor vehicle comprising this system.