Vehicle Clutch Control Using Speed-Dependent Motor Temperature Thresholds
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Solution Overview
Problem
In hybrid and electric vehicles, the existing clutch control systems based on motor temperature lead to inefficient regenerative energy recovery due to delayed clutch disconnection and reconnection, particularly during high-speed driving and deceleration, resulting in reduced regeneration efficiency.
Innovation Solution
A vehicle control device that uses temperature and vehicle speed sensors to dynamically adjust the clutch connection and disconnection thresholds, allowing earlier disconnection at higher speeds and earlier reconnection during deceleration, with additional adjustments based on brake pedal input and battery charge level to optimize regenerative energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the clutch is controlled to operate at the maximum rotation speed based on motor temperature, then the motor movable range is expanded and power performance is improved, but the motor temperature is always high and the clutch disconnection time increases, reducing regeneration efficiency
Solution Approach 1:
The patent applies dynamics by making the clutch control strategy adaptive rather than static. The controller dynamically adjusts clutch connection/disconnection timing based on real-time motor temperature and vehicle speed conditions. During acceleration, the clutch remains connected to maximize motor power output, while during deceleration, the clutch is reconnected earlier to enable regenerative braking, thus dynamically optimizing both power performance and regeneration efficiency
Solution Approach 2:
The patent changes the control parameters from fixed temperature-based thresholds to speed-dependent temperature thresholds. The upper limit rotation speed and clutch control temperatures are adjusted according to vehicle speed, allowing the system to optimize regeneration efficiency at high speeds while maintaining power performance at low speeds. This parameter adaptation resolves the contradiction between maintaining high motor operation and enabling timely regeneration
2Reliability
If the clutch is disconnected when motor temperature exceeds the upper limit, then the motor is protected from excessive load, but the clutch cannot be reconnected during deceleration if temperature remains above the lower limit, causing loss of regenerative energy
Solution Approach 1:
The patent changes the fixed temperature parameters into speed-dependent parameters. The upper and lower limit temperatures for clutch control are adjusted based on vehicle speed - at higher speeds, the lower limit temperature is raised, allowing earlier clutch reconnection during deceleration. This enables the system to maintain motor protection while capturing regenerative energy that would otherwise be lost, directly resolving the contradiction between reliability and energy loss
3Stability of the object's composition
If the clutch is reconnected based on a fixed lower limit temperature, then the motor operation is stabilized, but during high-speed deceleration the clutch cannot be reconnected in time, reducing regeneration efficiency in the high-speed region
Solution Approach 1:
The patent implements parameter changes by making the lower limit temperature for clutch reconnection speed-dependent. At high vehicle speeds, the lower limit temperature is increased, allowing the clutch to be reconnected earlier during deceleration events. This enables timely regeneration at high speeds while maintaining motor operation stability through controlled reconnection timing. The speed-adaptive temperature parameters directly resolve the contradiction between stability and high-speed regeneration efficiency
Data Source
AI summary
A vehicle control device includes a motor, a transmission unit, a temperature sensor that detects a temperature of the motor, a vehicle speed sensor that detects a vehicle speed, and a controller. The controller controls switching of the transmission unit based on a first temperature determined in accordance with the vehicle speed as the temperature at which the transmission unit is switched from connection to disconnection, and a second temperature determined in accordance with the vehicle speed as the temperature at which the transmission unit is switched from the disconnection to the connection. The first temperature decreases as the vehicle speed increases. The controller switches the transmission unit from the connection to the disconnection based on the first temperature, and then switches the transmission unit from the disconnection to the connection based on the second temperature.