Wheel Brake Pressure Reduction With Multiplexed Piston Control
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Solution Overview
Problem
Existing braking systems face challenges with high component counts, complex designs, and high motor demands, leading to inefficiencies in pressure control and increased costs, particularly during dynamic braking operations like ABS and ESP.
Innovation Solution
A braking system with a minimal valve configuration using a double-stroke piston and intelligent multiplexing, allowing simultaneous or sequential pressure control in wheel brakes, reducing cycle times and motor requirements through precise pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional braking system with master brake cylinder and isolating valves is used, then modular design and standard components are achieved, but a high number of components including valves, complex two-chamber master brake cylinder, and simulator are required
Solution Approach 1:
The patent combines the master brake cylinder and pressure supply unit into a single integrated unit, eliminating the need for separate isolating valves and reducing the total component count. The single-chamber design merges functions that were previously separated into two chambers with intermediate pistons and valves.
Solution Approach 2:
The integrated unit serves multiple functions: it acts as both the master brake cylinder for pedal operation and the pressure supply unit for ABS/ESP operations. The single piston performs both brake force generation and pressure regulation functions that previously required separate components.
2Reliability
If multiplex operation with both master brake cylinder and pressure supply unit connected via isolating valves is used, then no differential pressures in brake circuits are created, but a high number of valves and complex components are required
Solution Approach 1:
The patent removes the isolating valves from the system by integrating the pressure supply unit directly into the master brake cylinder. The differential pressure issue is eliminated by taking out the intermediate valve components that created pressure differentials between circuits.
Solution Approach 2:
By merging the master brake cylinder and pressure supply unit into one integrated component, the patent eliminates the need for isolating valves that separated the circuits. The single-chamber design ensures uniform pressure distribution without creating differential pressures between different brake circuits.
3Productivity
If pressure supply unit with double-stroke piston and different hydraulic cross-sectional areas is used, then continuous delivery and motor downsizing potential are achieved, but high dynamic requirements for motor torque during normal operation prevent full exploitation
Solution Approach 1:
The patent employs a double-stroke piston with variable hydraulic cross-sectional areas that dynamically adjusts the effective area during different strokes. This dynamic adjustment allows the motor to operate at lower torque levels during normal braking while maintaining continuous pressure delivery capability.
Solution Approach 2:
The system changes the hydraulic parameter (effective cross-sectional area) of the piston during operation. During the forward stroke, a larger area provides mechanical advantage for pressure build-up, while during the return stroke, a smaller area enables continuous delivery with reduced motor torque requirements.
4Reliability
If conventional inlet and outlet valves are used for pressure control, then pressure regulation is achieved, but cycle times are longer and motor requirements are higher
Solution Approach 1:
The integrated design pre-positions the piston and hydraulic fluid within the single chamber, eliminating the time required for fluid to travel through separate circuits and valves. The preliminary arrangement of components within the integrated unit reduces the cycle time for pressure build-up and release.
Solution Approach 2:
By merging the pressure build-up and pressure release functions into a single integrated unit with a single piston, the patent eliminates the sequential operation required by separate inlet and outlet valves. The combined design allows simultaneous or faster alternating pressure control actions, reducing the overall cycle time.
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
The system achieves high control quality and performance with fewer components, lower costs, and reduced motor size, enabling efficient pressure management in various braking modes with minimal noise and rapid response.
Implementation Method 1
the pressure in the wheel brakes is adjusted simultaneously or sequentially using a closed multiplexing method. This is achieved via a switching valve and the position-controlled operation of a driven piston for pressure build-up and pressure reduction
Implementation Method 2
A pressure sensor is used for control, measuring the pressure in the hydraulic connection between the piston-cylinder unit and the wheel brakes
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The invention relates to a method for controlled pressure reduction in wheel brakes (RB1, RB2, RB3, RB4) using a pressure supply unit (DE) comprising a piston-cylinder unit with at least one piston, wherein the piston defines at least one working chamber (A1, A2), the method comprising the following steps: a) establishing a fluid connection between at least one of the wheel brakes (RB1, RB2, RB3, RB4) and the working chamber via an open switching valve (SV1, SV2) associated with the wheel brake, b) operating the piston (3) to increase the volume of the working chamber (4), c) timing an outlet valve (AV, AV1) associated with a second of the wheel brakes (RB1, RB2, RB3, RB4) for a preferably simultaneous pressure reduction into a reservoir.