Electrified Axle Parking Brake Layout for Lower Drag Losses
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Solution Overview
Problem
Existing electrified vehicle drivetrains face challenges with high rotational speeds of parking brakes, leading to increased drag losses, decreased performance, and complex assembly and maintenance due to direct coupling with electric machines, necessitating substantial modifications to the driveline.
Innovation Solution
A brake component and reduction component are drivingly coupled in parallel to the driveline, with the brake component attached externally to the driveline and coupled to a low-speed section of the reduction component, allowing for a standard electric machine and reducing the need for additional attachment points, thus minimizing modifications and assembly complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the parking brake is directly coupled to the output of the motor or between the motor and reduction sets, then the electric machine can be integrated into the drivetrain, but the parking brake is subjected to high rotational speeds resulting in increased drag losses and decreased performance
Solution Approach 1:
A reduction component (gearbox) is introduced as an intermediary between the motor and the parking brake. The reduction component reduces the rotational speed transmitted to the parking brake, thereby decreasing drag losses while maintaining the integrated drivetrain configuration. The patent states: 'the brake component and reduction component are drivingly coupled in parallel to the driveline... the reduction component may reduce a rotational speed of an output of the electric machine'
Solution Approach 2:
The parking brake is coupled to a low-speed section of the reduction component through a shaft that is parallel to the rotor of the motor, creating a parallel coupling arrangement. This dimensional change in coupling configuration allows the brake to operate at reduced speeds while maintaining integration with the drivetrain. The patent specifies: 'coupled to a low-speed section of the reduction component through a shaft that is parallel to a rotor of the motor'
2Device complexity
If the parking brake is directly coupled to the motor output, then the drivetrain can be electrified, but the high rotational speeds reduce the lifespan of the parking brake and increase maintenance frequency
Solution Approach 1:
The reduction component serves as a protective intermediary that shields the parking brake from high rotational speeds, extending its lifespan and reducing maintenance requirements while maintaining drivetrain electrification
Solution Approach 2:
The parallel shaft configuration couples the brake to the low-speed section of the reduction component, creating a dimensional arrangement that protects the brake from high-speed operation while enabling electrified drivetrain functionality
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 configuration reduces energy losses, extends brake lifespan, and simplifies assembly and maintenance by allowing for a modular design with fewer attachment points, enabling the use of standard electric machines and reducing drag losses.
Implementation Method 1
The reduction component may incorporate a plurality of gears or other reducers to reduce the rotational speed
Implementation Method 2
The brake component may incorporate a brake that may act as a parking brake... A brake may be used to stop or prevent the rotation of the shaft
Data Source
AI summary
An electrified drivetrain may include a motor, a speed reduction gearbox driven by the motor, and a parking brake coupled to a low-speed portion of the speed reduction gearbox through a shaft that is parallel to a rotor of the motor.