Electric Vehicle Differential Lock for Inclined Stationary Maintenance
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Solution Overview
Problem
Electric vehicles with single-shaft axles struggle to maintain a stationary state on inclined surfaces due to differential rotation between wheels, leading to wheel wear and road damage, and existing solutions complicate the driving system by requiring additional brake states.
Innovation Solution
A driving system with a differential apparatus that includes a clutch member and actuator to allow or stop differential rotation, and a brake mechanism to maintain vehicle stationarity by controlling rotation between the electric motor and differential apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a differential apparatus is provided to allow differential rotation of wheels, then wheel wear and road surface damage are prevented during turning, but the stationary state of the vehicle cannot be maintained on inclined surfaces due to rotation difference absorption
Solution Approach 1:
The differential lock mechanism dynamically switches between two states: unlocked state during normal operation to allow differential rotation and prevent wheel wear, and locked state during stationary maintenance to prevent rotation difference absorption. This dynamic switching resolves the contradiction by adapting the differential apparatus behavior to different operational requirements.
Solution Approach 2:
The invention changes the parameter of differential rotation from 'allowed' to 'stopped' by engaging the differential lock. This parameter change enables the system to maintain stationary state on inclined surfaces while still providing differential rotation capability during turning operations, thus resolving the contradiction between preventing wheel wear and maintaining stationarity.
2Reliability
If a drum brake is added to stop wheels for stationary maintenance, then the stationary state can be maintained, but the driving system becomes complicated and increases in size
Solution Approach 1:
The differential lock mechanism serves multiple functions: it maintains stationary state on inclined surfaces by preventing differential rotation, and it can be integrated with the existing brake system. This multi-functionality eliminates the need for a separate drum brake system, reducing overall system complexity while maintaining stationary state capability.
Solution Approach 2:
The invention merges the stationary maintenance function with the existing brake system and differential apparatus. Instead of adding a separate drum brake, the differential lock is integrated into the power transmission path, combining the functions of differential control and stationary maintenance into a unified system, thereby reducing complexity.
3Device complexity
If electromagnetic clutch brake is used to maintain stationary state, then the system remains simple, but wheel wear and road surface damage occur during turning due to inability to absorb rotation difference
Solution Approach 1:
The invention segments the control functions by introducing a differential lock mechanism that operates independently from the electromagnetic clutch brake. The electromagnetic clutch brake maintains system simplicity for overall power transmission control, while the differential lock specifically handles rotation difference absorption during turning, preventing wheel wear without complicating the overall system.
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
The system effectively absorbs rotation differences between wheels during turning and maintains vehicle stationarity without increasing system complexity, preventing wheel wear and road damage while simplifying the braking mechanism.
Implementation Method 1
an electromagnetic clutch brake; when a controller confirms that an accelerator pedal is not depressed and a vehicle speed detected by a vehicle speed sensor is zero, an electric current flowing to an electromagnetic clutch brake is cut off and the electromagnetic clutch brake is closed
Data Source
AI summary
A driving system includes an electric motor, a transmission apparatus, a differential apparatus and a brake. The differential apparatus includes an input portion coupled to an output portion of the transmission apparatus, a pair of output portions, and a differential device that allows differential rotation of the pair of output portions. A brake is provided in a drive path from an output portion of the electric motor to the input portion of the differential apparatus. The differential apparatus includes a clutch member movable between a first position in which a differential rotation of the differential device is allowed and a second position in which the differential rotation of the differential device is stopped, a clutch actuator that moves the clutch member to the first position, and a holding portion that holds the clutch member to the second position when the clutch actuator is in a non-operating state.