Brake System Annular Piston Flow Control
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Solution Overview
Problem
Conventional brake systems experience hydraulic flow resistance issues during rapid brake pedal actuation, leading to reduced brake fluid flow and impaired braking performance at the mechanical fallback level, particularly due to damming between the separator valve and intake valves, which limits brake pressure and increases stopping distance.
Innovation Solution
The implementation of a restrictor to increase outflow resistance into the hydraulic fluid reservoir, optimizing the distribution of flow between nonreturn and pressure limiting valves, and using an annular prefill chamber with a stepped piston to enhance brake fluid distribution and pressure buildup in the brake circuits, thereby improving braking performance and compensating for air bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the brake pedal is rapidly actuated at the mechanical fallback level, then brake fluid flows rapidly into the brake circuits, but the intake valves produce hydraulic flow resistance that causes brake fluid to dam up between the separator valve and intake valves, reducing the useful effect of the annular piston principle
Solution Approach 1:
The patent introduces an intermediary chamber (annular piston chamber) between the reservoir and the brake circuits. This chamber acts as a buffer that receives brake fluid from the reservoir and distributes it to the brake circuits, mediating the flow to avoid the harmful damming effect caused by the intake valves' flow resistance.
Solution Approach 2:
The hydraulic system is segmented into distinct zones: the reservoir, the annular piston chamber, the separator valve, and the brake circuits. This segmentation allows the system to manage fluid flow in stages, with the annular piston chamber serving as an intermediate storage and distribution point that decouples the rapid pedal actuation from the valve flow resistance.
2Stress or pressure
If the annular piston chamber pressure rises rapidly due to dammed brake fluid, then brake pressure in the first brake circuit increases, but the time duration of this ideal state is shortened, reducing the maximum possible vehicle deceleration
Solution Approach 1:
The annular piston chamber is pre-filled with brake fluid and positioned to receive fluid from the reservoir before the braking event. When the brake pedal is actuated, the chamber is already prepared to rapidly transfer fluid to the brake circuits, extending the duration of effective pressure buildup without requiring the fluid to travel through the restrictive intake valves first.
Solution Approach 2:
The system maintains continuous useful action by keeping the annular piston chamber filled with brake fluid under pressure, ready to immediately supply the brake circuits when needed. This continuity ensures that the pressure buildup in the brake circuits is sustained for a longer duration, maximizing vehicle deceleration capability.
3Duration of action of moving object
If a restrictor is added to increase outflow resistance to the reservoir, then the ideal pressure rise time window is prolonged and brake fluid distribution is optimized, but the device complexity increases
Solution Approach 1:
The restrictor function is merged into the existing annular piston chamber structure. Rather than adding a separate restrictor component, the chamber's geometry and fluid pathways are designed to inherently provide the necessary flow resistance, achieving the desired pressure control without increasing device complexity.
Solution Approach 2:
The annular piston chamber serves multiple functions: it acts as a fluid reservoir, a pressure buffer, a flow distributor, and implicitly as a restrictor element. This multi-functionality eliminates the need for additional dedicated components, maintaining system simplicity while achieving prolonged pressure rise duration.
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 increases brake pressure and reduces stopping distance by maximizing brake fluid inflow into the brake circuits, prolonging the ideal pressure rise and maintaining optimal braking performance even at mechanical fallback levels, while ensuring agreeable pedal feel and efficient fluid management.
Implementation Method 1
The annular prefill chamber (20) is designed to communicate with the first brake circuit (3a) via a nonreturn valve (30)
Implementation Method 2
The implementation of a restrictor to increase outflow resistance into the hydraulic fluid reservoir
Implementation Method 3
one piston in the form of a stepped piston having at least two hydraulically active surface areas of different sizes
Implementation Method 4
The master brake cylinder of the hydraulic vehicle brake system includes a first pressure chamber and a second pressure chamber
Data Source
AI summary
A brake system for a vehicle, including: a master brake cylinder having a first chamber, a rod piston, which, together with at least one first hydraulically active surface area, bounds the first chamber, a second chamber and a floating piston; the rod piston being configured with or couplable to a second hydraulically active surface area; the second hydraulically active surface area bounding an auxiliary chamber of the master brake cylinder or of another brake cylinder, and the auxiliary chamber being attached to an accumulator chamber and/or to the hydraulic reservoir via a first nonreturn valve and a restrictor that is configured in a further fluid line.