Brake Device Piston Switching for Weight Reduction
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Solution Overview
Problem
Existing brake devices with hydraulic booster stages face challenges in reducing switching effort and complexity, particularly with high-pressure accumulators that increase weight, structural space requirements, and switching effort, while aiming to replicate the haptic feedback and mechanical interfaces of negative-pressure brake force boosters.
Innovation Solution
A brake device with a circulation booster stage using two separate pistons, one for autonomous actuation and another for manual actuation, operated through a positively pressure-controlled and mechanically simple arrangement of hydraulic passages in a displaceable piston rod, eliminating the need for high-pressure accumulators and separate electrical or electromagnetic valve switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure accumulators are used as pressure source, then autonomous actuation is enabled, but weight increases
Solution Approach 1:
The patent removes the high-pressure accumulator from the system entirely. Instead of storing pressure in advance, the system generates hydraulic pressure on-demand through an electric pump, eliminating the heavy accumulator component while maintaining autonomous actuation capability.
Solution Approach 2:
The mechanical spring-based or accumulator-based pressure storage system is replaced with an electrically driven pump system. The electric pump, controlled by a control unit, generates hydraulic pressure electronically controlled, substituting mechanical pressure storage with an electro-hydraulic generation system.
2Reliability
If high-pressure accumulators are used as pressure source, then autonomous actuation is enabled, but structural space expenditure increases
Solution Approach 1:
The high-pressure accumulator, which occupies significant structural space, is completely removed from the booster stage. The on-demand pump system requires minimal space compared to pressure storage accumulators.
Solution Approach 2:
The system transitions from static pressure storage (accumulator) to dynamic pressure generation (on-demand pump). The pump only operates when pressure is needed, allowing for a compact design without large pressure vessels.
3Adaptability or versatility
If electrically switchable valve devices are used for actuation mode switching, then actuation mode control is achieved, but device complexity increases
Solution Approach 1:
The patent combines the functions of multiple valves and switching mechanisms into a single integrated control unit. The control unit electronically manages both the pump operation and the selection between autonomous and manual actuation modes, eliminating the need for separate electrically switchable valve devices.
Solution Approach 2:
The control unit serves multiple functions: it controls the electric pump, selects between autonomous and manual actuation modes, and manages the hydraulic circuit. This multi-functional approach reduces the number of separate components and simplifies the overall system.
4Adaptability or versatility
If separate electrical or electromagnetic valve switching devices are used, then actuation mode switching is achieved, but switching effort increases
Solution Approach 1:
Multiple valve functions are merged into the integrated control unit, which electronically switches between actuation modes without requiring separate electrical or electromagnetic valve switching devices. This reduces switching effort and simplifies the control mechanism.
Solution Approach 2:
Electrical or electromagnetic valve switching devices are replaced with an electronically controlled pump system managed by a microprocessor-based control unit. The switching is achieved through electronic control signals rather than mechanical or electromagnetic valve actuation.
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 simplifies switching between actuation modes, reduces weight and structural space, maintains similar comfort and assembly interfaces to conventional negative-pressure brake force boosters, and allows for reliable external actuation with haptic feedback, while being modular and adaptable for various customer-specific characteristics.
Implementation Method 1
The operative switching between the pistons may in this case be performed in a particularly simple manner in a positively pressure-controlled manner and at the same time mechanically by means of a suitable arrangement of hydraulic passages in a piston rod which is displaceable relative to the pistons
Implementation Method 2
Through the use of two pistons, in particular in conjunction with the use of a pressure sensor for measuring the pressure in the booster stage, the brake device can be externally actuated in a reliable manner
Data Source
AI summary
A brake device having a hydraulic booster stage for a hydraulic motor vehicle brake system is provided, which brake device, within normal boosting operation, can be operated both in an autonomous, driver-independent actuation mode with electronic control and in a manual actuation mode controlled by the driver, and outside normal boosting operation, can be operated in an emergency mode with a non-boosted actuation force generated by the driver alone, in the case of which brake device it is proposed that, within normal boosting operation, each actuation mode is assigned a dedicated piston in a booster housing of the booster stage, which piston is acted on directly with the boosting force and transmits this mechanically to components connected functionally downstream.