Electric Vehicle Parking Brake Using Multi-Speed Gearbox Locking
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Solution Overview
Problem
Commercial vehicles face challenges in implementing a compact and efficient parking brake system that can effectively lock both wheels to prevent rolling, especially in electric or hybrid drivetrains, where the existing systems are often large and complex, affecting vehicle weight and space for additional components.
Innovation Solution
A vehicle drivetrain system utilizing multiple-speed gearboxes with actuated driving stages and differential locks, where concurrent activation of gear stages and elastic couplings allows for a bistable locking mechanism to couple wheels, enabling a compact and efficient parking brake function, and an auxiliary device for manual release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring brake is placed axially behind the service brake portion in the combination cylinder housing to realize parking brake function, then the parking brake function is achieved, but the assembly size becomes relatively large
Solution Approach 1:
The patent combines the parking brake function with the existing service brake system by integrating a pawl mechanism into the differential housing. The parking brake utilizes the differential case and pinion gear as mounting structures, merging the parking brake function with the drive train components rather than adding a separate axial assembly behind the service brake.
Solution Approach 2:
The differential housing serves multiple functions: it houses the differential mechanism for power distribution and simultaneously provides mounting structures (case and pinion gear) for the parking brake pawl mechanism. This multi-functionality eliminates the need for dedicated separate parking brake housing components.
2Adaptability or versatility
If a combination cylinder housing with both service brake and parking brake portions is used, then both brake functions are integrated, but the device complexity increases
Solution Approach 1:
The parking brake system is segmented into distinct functional components: a pawl mounted on the differential case, a corresponding rack on the pinion gear, and a spring mechanism. This segmentation allows each component to be independently designed and maintained while working together to provide the parking brake function.
Solution Approach 2:
The pawl-rack mechanism acts as an intermediary between the parking brake spring force and the differential components. The pawl engages with the rack on the pinion gear to prevent reverse rotation, providing a simple mechanical intermediary that translates spring force into effective wheel locking without complex hydraulic or electronic systems.
3Weight of moving object
If the parking brake assembly is made compact to reduce vehicle weight and space, then weight and space are reduced, but the reliability of wheel locking may be compromised
Solution Approach 1:
The parking brake spring provides a counteracting force that opposes any reverse rotation tendency of the wheels. This spring force acts as a mechanical counterweight to gravitational forces and inertial forces that might cause the vehicle to roll, ensuring reliable wheel locking without requiring heavy-duty components.
Solution Approach 2:
The parking brake mechanism is designed to be self-actuating through the spring-loaded pawl that automatically engages with the rack on the pinion gear when the vehicle is stationary. The spring maintains constant pressure on the pawl, ensuring automatic engagement and disengagement based on wheel rotation direction, eliminating the need for complex actuation systems.
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
This solution reduces the size and complexity of the braking system, allowing for lighter vehicles with additional space for components like batteries, and ensures effective wheel locking without rolling, even when power is removed, with a manual release mechanism for convenience.
Implementation Method 1
an elastic coupling mechanically linked to the second clutch. The elastic coupling may permit rotation of an input of the first multi-speed gearbox to align the first clutch with the first driving stage while the second clutch is engaged with the second driving stage
Data Source
AI summary
A commercial vehicle includes at least one driven axle, a service brake, at least one propulsion engine, and wheels. A parking brake function of the vehicle is achieved by a bistable locking means that acts on both wheels. A first and second multi-speed gearbox having respective first and second gear stages are each activated by an actuator and coupled to the wheels. The parking brake function is achieved at least in-part by concurrently activating the first and second gear stages. A computing device is configured to activate the bistable locking means when the commercial vehicle is at a standstill and configured to send a brake request via an electronic signal to an electronic brake control unit to activate the service brake.