Electric Drivetrain Parking Brake With Torque-Multiplying Gears
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Solution Overview
Problem
Conventional electric drivetrains face challenges in implementing effective parking brake systems at the wheel level due to elevated torque requirements, lack of redundancy, and increased complexity, particularly in heavy-duty vehicles, which affect safety and reliability.
Innovation Solution
An electric drivetrain system with a multiplication gear assembly and a parking brake assembly that reduces braking torque requirements, incorporates redundancy through independent brake calipers and ECUs, and includes a casing to protect components, ensuring reliable operation even in the event of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional driveline parking brake is used in electrified axles, then the vehicle can be parked using the differential ratio, but the torque requirements become excessively high and complexity increases
Solution Approach 1:
The brake system is segmented into two independent circuits (first and second brake calipers) with separate hydraulic pathways and ECUs. This segmentation allows the system to maintain parking brake functionality even if one circuit fails, thereby improving reliability without requiring a complete system redesign that would increase complexity.
Solution Approach 2:
A multiplication gear assembly with a pinion gear and gear is introduced as an intermediary mechanical element between the electric motor and the brake calipers. This intermediary provides mechanical advantage to reduce the torque requirement at the brake caliper level while maintaining the overall system reliability, avoiding the need for excessively high torque direct application.
2Ease of operation
If wheel-level parking brake systems are implemented in heavy-duty vehicles, then direct wheel braking is achieved, but the torque requirements and cost increase significantly
Solution Approach 1:
The multiplication gear assembly acts as a mechanical intermediary that amplifies the torque output from the electric motor before applying it to the brake calipers. The pinion gear engages with the gear to provide mechanical advantage, reducing the power requirement at the motor level while still achieving sufficient braking torque at the wheel level for heavy-duty vehicles.
Solution Approach 2:
The system changes the torque parameter distribution by using a dual-circuit brake system where each caliper can operate independently with reduced torque requirements. The multiplication gear assembly modifies the torque transmission parameters, allowing effective parking brake operation with lower peak torque demands on the electric motor.
3Reliability
If a single brake caliper system is used, then the system is simpler, but redundancy is lost and reliability decreases
Solution Approach 1:
The brake system is divided into two independent hydraulic circuits with separate calipers, each capable of independent operation. This segmentation provides redundancy because if one circuit or caliper fails, the other can still provide parking brake functionality, improving reliability without requiring a completely redundant dual-system architecture that would double the complexity.
Solution Approach 2:
Each brake caliper circuit is designed with local independence, having its own hydraulic pathway, ECU control, and mechanical connection to the multiplication gear assembly. This local quality of independence allows one side to function even if the other fails, providing redundancy while keeping each individual circuit relatively simple in structure.
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 secures vehicles in park with reduced torque demands, provides redundancy to maintain functionality in case of component failures, and is cost-effective for heavy-duty applications.
Implementation Method 1
The multiplication gear assembly includes a first gear and a second gear operatively coupled to the first gear to reduce a braking torque required by the parking brake assembly to secure the vehicle in park
Implementation Method 2
a gear box adapted to be operatively coupled to wheels of the vehicle, wherein the gear box includes a differential
Implementation Method 3
an electric motor
Implementation Method 4
a plurality of parking brake calipers operatively coupled to the brake rotor. The plurality of parking brake calipers is configured to selectively engage the brake rotor to slow the rotation of the brake rotor
Data Source
AI summary
An electric drivetrain adapted to be installed in a vehicle to control movement of the vehicle. The electric drivetrain includes: a gear box adapted to be operatively coupled to wheels of the vehicle, wherein the gear box includes a differential; a multiplication gear assembly operatively coupled to the differential; and a parking brake assembly coupled to the multiplication gear assembly. The multiplication gear assembly includes a first gear and a second gear operatively coupled to the first gear to reduce a braking torque required by the parking brake assembly to secure the vehicle in park.