Differential Lock Parking Control for Lightweight Vehicles
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Solution Overview
Problem
Conventional parking brakes for light-weight vehicles, such as micro-cars and buggies, result in weight gain and are not effective in securing the vehicle's stationary state, as they rely on wheel locking mechanisms that can fail to prevent movement when differential motion between wheels is not properly locked.
Innovation Solution
A safe parking system utilizing a motor, final drive with a differential gear and lock mechanism, an actuator, and a controller to lock differential motion between the side gears, ensuring the vehicle remains stationary without relying on wheel locking mechanisms, even when power is lost, by using a normally-closed lock-up differential or alternative locking devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional parking brakes (mechanical drum brakes or dog clutch) are used to secure the vehicle, then the vehicle can be kept stationary, but the vehicle weight increases
Solution Approach 1:
The patent combines the parking brake function with the differential lock mechanism into a single integrated system. The differential lock, which normally prevents wheel slip during acceleration, is repurposed to also secure the vehicle during parking by locking the differential gear, thereby eliminating the need for separate parking brake components in light-weight vehicles
Solution Approach 2:
The differential lock mechanism is designed to serve multiple functions: it acts as both a traction control device during vehicle operation and a parking brake when the vehicle is stopped. This multi-functionality allows the system to provide reliable stationary state security without adding dedicated parking brake weight
2Reliability
If conventional parking brakes with wheel locking mechanisms are used, then the vehicle can be secured, but the system complexity increases
Solution Approach 1:
The patent merges the parking brake function with the existing differential lock mechanism, combining two functions into one system. This reduces overall system complexity by eliminating redundant components and control systems that would be required for separate parking brake and differential lock systems
Solution Approach 2:
The differential lock mechanism is designed to serve multiple functions: it acts as both a traction control device during vehicle operation and a parking brake when the vehicle is stopped. This multi-functionality allows the system to provide reliable stationary state security without adding dedicated parking brake weight
3Ease of operation
If the differential lock is released during parking, then the vehicle can move freely, but the vehicle may unintentionally move or turn
Solution Approach 1:
The patent inverts the normal operation of the differential lock. Instead of the lock being engaged during driving and released during parking, the system maintains the lock engaged during parking to prevent unintentional movement. The differential motion freedom is restored only when the vehicle is actively being driven and the driver needs traction assistance
Data Source
AI summary
A safe parking system is provided with: a torque-generating motor; a final drive including side gears drivingly coupled with the motor, a differential gear with a lock to prevent a differential motion between the side gears and an actuator for releasing the lock; an ignition key having an ON position and an OFF position; a differential-lock switch having an open position and a closed position; a switching unit for selecting whether the actuator is turned on or off; and a controller configured to, when the ignition key is detected to be in the OFF position, turn off the actuator if the differential-lock switch is in the open position, and execute no operation about the actuator if the differential-lock switch is in the closed position.