Vehicle Brake Layout Using Higher-Speed Output Shafts
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Solution Overview
Problem
There is a need to reduce braking torque and brake dimensions in motor vehicles, particularly in hybrid and electric vehicles, while maintaining braking effectiveness, and to minimize unsprung mass to improve dynamic behavior.
Innovation Solution
The design incorporates disc brakes that exert braking torque on output shafts rotating at a higher speed than the wheels, allowing for reduced braking torque and brake size, and integrates electric motors to generate part of the braking torque, thereby reducing the number of components attached to the wheels and minimizing unsprung mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If disc brakes are designed to exert braking torque directly on wheels, then braking effectiveness is maintained, but brake dimensions and unsprung mass increase
Solution Approach 1:
The patent introduces an intermediary mechanical member (output shaft of transmission assembly) between the brake and the wheel. The brake exerts braking torque on this intermediary member which rotates at a different speed than the wheel, allowing the brake to be decoupled from direct wheel attachment and reducing unsprung mass.
Solution Approach 2:
The patent changes the operating parameter of the brake by having it act on a rotating member with different rotational speed characteristics than the wheel. This parameter change allows for reduced brake dimensions while maintaining effective braking through the transmission of torque via the differential mechanism.
2Adaptability or versatility
If multiple components are directly fixed to wheels for braking and drive functions, then functional requirements are met, but design flexibility is reduced
Solution Approach 1:
The patent extracts the brake from direct wheel attachment and relocates it to act on the output shaft of the transmission assembly. This separation removes the brake from the wheel assembly, reducing the number of components directly fixed to wheels and increasing design flexibility.
Solution Approach 2:
The output shaft of the transmission assembly serves multiple functions: it transmits drive torque from the electric motor and simultaneously serves as the mounting point for the brake. This multi-functionality reduces the need for separate dedicated components on the wheels.
3Force
If electric machine operates solely as motor, then drive torque is provided, but braking capability is insufficient
Solution Approach 1:
The patent makes the electric machine dynamic in its operational mode, allowing it to switch between motor mode (providing drive torque) and generator mode (providing regenerative braking). This dynamic capability enables the same component to fulfill both propulsion and braking functions.
Solution Approach 2:
The patent converts the harmful effect of kinetic energy during braking into useful electrical energy through regenerative braking. The electric machine operates as a generator to recover energy that would otherwise be lost, transforming the braking process from an energy-wasting operation into an energy-recovering opportunity.
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 approach reduces the size and weight of brakes, enhances design flexibility, and improves vehicle dynamics by distributing braking torque through higher-speed shafts and utilizing electric motors as generators, achieving effective braking with reduced components and mass.
Implementation Method 1
When it is used as electric generator, the electric machine absorbs mechanical power from the drive wheels, thus generating a braking torque exerted upon the drive wheels. Said absorbed mechanical power is converted into electrical power
Implementation Method 2
a pad supported by the body and selectively movable to exert a pressure upon the disc and, hence, a braking torque - through friction - upon the relative front or rear wheel
Data Source
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AI summary
A motor vehicle (1, 1', 1", 1‴, 1ʺʺ, 1ʺ‴) comprising: a first driving member (30, 35; 70"; 85"); a wheel (11, 12; 16, 17), which is angularly integral to a first shaft (20, 21; 22, 23), operatively connected to the first driving member (30, 35; 70"; 85") and capable of rotating, in use, at a first rotation speed (ω1); and a brake (50, 51, 52, 53; 50"; 50‴; 50ʺʺ, 51ʺʺ); the brake (50, 51, 52, 53; 50", 51"; 50ʺʺ, 51ʺ‴) can selectively be operated so as to directly exert a braking torque upon a second shaft (31, 36; 44; 95ʺ, 105ʺ, 106ʺ) of the motor vehicle (1, 1', 1ʺ, 1‴, 1ʺʺ, 1ʺ‴) other than the first shaft (20, 21; 22, 23) and capable of rotating at a second rotation speed (ω2; ω3; ω2; ω5, ω6), which is different from the first rotation speed (ω1); the second shaft (31, 36; 44; 95", 105", 106'') is operatively connected to the first shaft (20, 21; 22, 23).