Fast-fill tandem master cylinder with segmented dual-piston circuit
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Solution Overview
Problem
Current braking systems experience a delay in brake pad contact with the rotor during initial actuation, leading to minimal pressure buildup and unsettling pedal feedback due to the lack of physical contact, which is not effectively addressed by existing fast-fill systems that require larger pistons and boost systems.
Innovation Solution
A master cylinder design featuring a fast-fill piston assembly with a primary piston and secondary piston, where the secondary piston is biased by a spring to rapidly increase pressure in downstream braking circuits, allowing for quick fluid displacement without the need for a larger boost system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a larger diameter piston is used to quickly fill the braking system with fluid, then the fast-fill function is improved, but the force required to move the piston increases, necessitating a larger boost system
Solution Approach 1:
The braking system is divided into two independent circuits: a primary braking circuit with a first piston for normal braking operations, and a fast-fill circuit with a second piston specifically designed to rapidly fill the hydraulic system. This segmentation allows each piston to be optimized for its specific function, with the second piston having a larger diameter dedicated solely to fast-fill operations without requiring an oversized boost system for the entire braking mechanism.
Solution Approach 2:
A check valve is introduced as an intermediary component that selectively directs fluid flow. During normal braking, the check valve allows fluid to flow to the brake calipers through the first piston. During fast-fill operations, the check valve redirects fluid flow to rapidly fill the hydraulic system through the second piston. This intermediary component enables the system to achieve fast-fill functionality without requiring the entire braking system to be oversized.
2Productivity
If a larger diameter piston is used to rapidly displace fluid, then the fast-fill function is improved, but the device complexity increases due to the need for a larger boost system
Solution Approach 1:
The braking system is divided into two independent circuits: a primary braking circuit with a first piston for normal braking operations, and a fast-fill circuit with a second piston specifically designed to rapidly fill the hydraulic system. This segmentation allows each piston to be optimized for its specific function, with the second piston having a larger diameter dedicated solely to fast-fill operations without requiring an oversized boost system for the entire braking mechanism.
Solution Approach 2:
The master cylinder assembly serves multiple functions through its dual-circuit design. The first piston handles normal braking fluid displacement, while the second piston with larger diameter specifically handles rapid system filling. This multi-functionality allows the system to achieve fast-fill capability without requiring the entire boost system to be oversized, thereby reducing overall device complexity while maintaining high productivity during fast-fill operations.
3Loss of time
If a larger quantity of fluid is displaced to quickly take up the gap, then the braking response time is improved, but the pedal feedback difference becomes more pronounced
Solution Approach 1:
The braking system is divided into two independent circuits: a primary braking circuit with a first piston for normal braking operations, and a fast-fill circuit with a second piston specifically designed to rapidly fill the hydraulic system. This segmentation allows the second piston to quickly displace fluid and close the gap between brake pads and rotor, reducing braking response time, while the primary circuit maintains normal pedal feedback characteristics through the first piston.
Solution Approach 2:
The check valve acts as an intermediary that selectively routes fluid flow based on system conditions. During initial actuation when the gap needs to be closed, the check valve directs fluid through the fast-fill circuit to rapidly eliminate the gap. Once the gap is closed, normal braking operations proceed through the primary circuit, providing consistent pedal feedback. This intermediary component enables rapid gap closure without permanently altering the normal braking feedback characteristics.
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 design minimizes the delay in brake engagement and reduces unsettling pedal feedback by rapidly increasing pressure in the braking system, achieving effective fast-fill functionality without the requirement for a larger boost system.
Implementation Method 1
a secondary piston within the second chamber
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A fast-fill braking system in one embodiment includes a master cylinder, a first chamber within the master cylinder, a second chamber within the master cylinder located forward of the first chamber, a fast-fill piston within the first chamber, a primary piston within the first chamber and movable with respect to the fast-fill piston, and a secondary piston within the second chamber.