EV Start Control Device for Dog Clutch Synchronization
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Solution Overview
Problem
In electrically driven vehicles with transmissions having a starting dog clutch, there is a risk of sudden motor rotation when attempting to start due to misalignment of engaging teeth, leading to incomplete engagement and potential vehicle delay.
Innovation Solution
A starting control device that limits the electric motor's output until the starting dog clutch is fully engaged, ensuring synchronized rotation speeds for proper gear engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric motor output is controlled according to the required driving force during EV start, then the vehicle starting performance is improved, but the electric motor rotation may abruptly increase when the starting dog clutch is not engaged due to misalignment of engaging teeth
Solution Approach 1:
The control device performs preliminary synchronization of rotation speeds between the electric motor and transmission input shaft before engaging the starting dog clutch. This preliminary action ensures that the engaging teeth are properly aligned when the clutch is engaged, preventing the harmful effect of abrupt motor rotation while maintaining good starting performance.
Solution Approach 2:
The control device changes the motor output parameter during the starting process. Initially, the motor output is limited to synchronize rotation speeds and ensure proper clutch engagement. After engagement is confirmed, the motor output is increased to meet the required driving force, thus resolving the contradiction between starting performance and engagement reliability.
2Ease of operation
If the phases of the dog teeth are in agreement during clutch engagement, then the engagement process is simplified, but the dog teeth will collide and the gears cannot be engaged
Solution Approach 1:
The control device uses feedback from rotation speed sensors to monitor the relative rotation speeds of the electric motor and transmission input shaft. Based on this feedback, the control device adjusts the motor output to maintain appropriate speed difference during engagement, preventing tooth collision while ensuring successful engagement.
Solution Approach 2:
The control device dynamically adjusts the motor output during the engagement process. By continuously monitoring rotation speeds and adjusting motor torque in real-time, the system maintains optimal engagement conditions without requiring complex mechanical synchronization mechanisms, thus simplifying the engagement operation while ensuring reliability.
Data Source
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AI summary
To provide a starting control device for an electrically driven vehicle that is configured to suppress an abrupt increase in the rotation of the electric motor at the time of an EV start of the vehicle from a released state of the starting dog clutch. In the electrically driven vehicle, an EV start is carried out by transmitting the output of the first motor/generator (MG1) to the drive wheels (19) via the third engagement clutch (C3) that is meshing engaged due to a stroke from a disengaged position. The output of the first motor/generator (MG1) is limited until the third engagement clutch (C3) comes into a meshed state in which the transmission of drive power is possible at the time of start from a released state of the third engagement clutch C3.