Vehicle Drive Apparatus Torque Reduction Switching
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Solution Overview
Problem
Existing vehicle drive apparatuses face challenges in smoothly switching between connected and disconnected states of rotary members transmitting driving force, leading to increased cost and weight due to high frictional forces and the need for large hydraulic circuits to manage torque variations.
Innovation Solution
A vehicle drive apparatus with a control unit that reduces torque output from the electric motor during the switching process, utilizing a linkage mechanism with a dog clutch design to facilitate smooth disconnection by reducing frictional forces, allowing the sleeve to move more efficiently between connected and disconnected states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the synchro sleeve is moved while torque is being transmitted between the first spline gear and the second spline gear, then the switching between connected and disconnected states can be achieved, but the friction force between the internal splines increases, requiring a larger hydraulic circuit capacity which increases cost and weight
Solution Approach 1:
The control unit reduces the torque output from the electric motor before the synchro sleeve moves to disconnect the side gear and wheel. This preliminary torque reduction minimizes the friction force between the internal splines during the disconnecting process, allowing the synchro sleeve to move smoothly without requiring a large-capacity hydraulic circuit, thereby reducing apparatus weight and cost
Solution Approach 2:
The system dynamically changes the torque parameter during the switching process. By reducing torque from the electric motor during the disconnecting phase and restoring it after disconnection, the system optimizes the friction conditions to enable smooth sleeve movement with minimal hydraulic capacity requirements
2Speed
If the force that pushes the synchro sleeve is not sufficiently large with respect to the force of friction, then the synchro sleeve cannot move quickly, but increasing the pushing force requires a larger hydraulic circuit which increases cost and weight
Solution Approach 1:
The control unit reduces torque output from the electric motor before the synchro sleeve movement begins. This preliminary action reduces the friction force between internal splines, enabling the synchro sleeve to move quickly with a smaller pushing force from a simplified hydraulic circuit
3Reliability
If a large hydraulic circuit capacity is used to move the synchro sleeve against maximum friction, then switching can be achieved under all torque conditions, but the cost and weight of the apparatus increase
Solution Approach 1:
The control unit reduces torque output from the electric motor before synchro sleeve movement. This ensures reliable switching under all torque conditions by minimizing friction during the critical movement phase, while allowing the use of a smaller, lighter hydraulic circuit
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables smooth switching between connected and disconnected states without significant increases in cost or weight, reducing the required driving force and minimizing impact during transitions, thus enhancing the efficiency and compactness of the drive apparatus.
Implementation Method 1
an electric motor (motor), a speed reducer, a differential
Implementation Method 2
it is necessary to push the synchro sleeve against the force of friction between internal splines of the synchro sleeve and the first and second spline gears
Data Source
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AI summary
A driving force transmission apparatus includes a linkage mechanism (51) that is able to carry out switchover between a connected state where first and second intermediate shafts 44, 45) are connected to each other so as to be non-rotatable relative to each other to transmit torque output from an electric motor (11) to a rear wheel (107R), and a disconnected state where the first and second intermediate shafts (44, 45) are disconnected from each other. When switching the driving force transmission apparatus from the connected state to the disconnected state, a control unit reduces the torque that is generated by the motor (11) during a drive state where the torque output from the motor is transmitted from the first intermediate shaft (44) to the second intermediate shaft (45), and switches the driving force transmission apparatus from the connected state to the disconnected state by controlling the linkage mechanism while the torque that is generated by the motor has been reduced.