Drive Axle Clutch Synchronization for Smooth Torque Delivery
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Solution Overview
Problem
Existing drive axle systems with electric motors face challenges in efficiently synchronizing the rotational speed of the clutch with the transmission gears during gear shifts, leading to potential torque clipping and inefficient torque delivery.
Innovation Solution
A method of controlling the axle assembly that includes a speed synchronization mode to adjust the rotational speed of the rotor without clipping torque, followed by a low torque synchronization mode if necessary, to ensure smooth gear shifts and prevent unintended acceleration or deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional clutch control methods are used during gear shifts, then the clutch can be engaged, but torque clipping occurs and torque delivery efficiency deteriorates
Solution Approach 1:
The system performs preliminary speed synchronization of the clutch with the transmission input shaft before engagement. The control method monitors rotational speeds and adjusts the clutch speed to match the transmission input shaft speed in advance, eliminating torque clipping during engagement and ensuring smooth torque delivery without energy loss.
2Speed
If the rotor rotational speed is adjusted rapidly to synchronize with the clutch, then synchronization speed improves, but torque control precision deteriorates due to unintended acceleration or deceleration
Solution Approach 1:
The control system dynamically adjusts the rotor rotational speed using two distinct modes: speed synchronization mode for rapid initial synchronization and low torque synchronization mode for precise final alignment. The system transitions between modes based on the synchronization progress, ensuring both rapid response and precise torque control without unintended acceleration or deceleration.
Solution Approach 2:
The system changes the operational parameters of the electric motor during the synchronization process. In speed synchronization mode, the motor operates with full torque capability for rapid speed adjustment. In low torque synchronization mode, the motor torque is limited to a lower value to achieve precise speed matching without causing unintended vehicle acceleration or deceleration.
3Reliability
If the clutch actuator operates continuously to engage the clutch, then engagement reliability improves, but component wear increases
Solution Approach 1:
The system performs preliminary speed synchronization before clutch engagement, ensuring that the clutch and transmission input shaft are already speed-matched when the clutch actuator engages the clutch. This eliminates the need for continuous clutch actuator operation during the synchronization process, reducing wear while maintaining reliable engagement through proper timing and speed matching.
Data Source
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AI summary
A method of controlling an axle assembly. The method includes executing a speed synchronization mode and operating a clutch actuator to shift a clutch from a neutral position toward an engaged position. The method may also include executing a low torque synchronization mode when the clutch cannot be shifted from a neutral position to an engaged position within a first predetermined period of time.