Concentric Electric Brake Booster Nesting Ball Screw
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Solution Overview
Problem
Existing vehicle brake systems that rely on engine vacuum for power-assisted braking are inadequate in vehicles without engine vacuum, such as hybrid or electric vehicles, as they either compromise the manual push rod actuation or increase underhood volume with extended designs.
Innovation Solution
A compact electric brake boost assembly that includes a master cylinder, ball screw assembly, and brake pedal push rod, where a motor-driven ball screw assembly actuates the primary piston, allowing for manual push through and electric power assistance without the need for engine vacuum, reducing overall length and underhood volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an electrically powered brake booster is implemented to provide power-assisted braking in vehicles without engine vacuum, then braking assistance is achieved, but the overall length of the combined master cylinder and electric booster increases, consuming more underhood volume
Solution Approach 1:
The invention places the ball screw assembly inside the hollow piston of the master cylinder, creating a nested configuration where the electric booster components are housed within the existing master cylinder structure. This eliminates the need for separate external booster housing, thereby reducing the overall length and underhood volume while maintaining electric power-assisted braking functionality
Solution Approach 2:
The invention merges the master cylinder and electric booster into a single integrated assembly. The ball screw assembly is drivably connected to the piston, and both components share a common housing structure, combining two previously separate systems into one compact unit that reduces space requirements
2Power
If the brake actuation mechanism is modified to provide electric power assistance, then power-assisted braking is achieved, but the manual push rod actuation function is compromised or lost
Solution Approach 1:
The invention creates a dynamic system where the ball screw assembly can be selectively engaged or disengaged from the piston. The push rod remains mechanically connected to the piston, allowing manual actuation to always function. The electric motor provides assistive force that can be activated or deactivated as needed, creating a flexible system that adapts between manual-only, electric-assist, or full-electric operation modes
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 provides a vacuum-independent braking system that retains manual push through functionality while reducing underhood volume and length, offering efficient braking assistance in vehicles without engine vacuum, enhancing braking performance and reducing operational complexity.
Implementation Method 1
The ball screw assembly is arranged to actuate the primary piston in response to actuation of a motor that is drivably connected to the ball screw assembly
Implementation Method 2
The plunger defines a plunger bore having a control spring disposed therein. The control spring engages an end of the brake pedal push rod and an end of the plunger
Data Source
AI summary
An electric booster and master brake cylinder assembly includes a master cylinder housing, a booster housing, a primary piston, and a ball screw assembly. The master cylinder housing defines a piston bore. The booster housing is attached to the master cylinder housing and defines a bore. The primary piston is slidably positioned within the piston bore and has an axially extending end portion that extends into the bore. The ball screw assembly is at least partially disposed within the bore of the booster housing.