Stepped Piston Pressure Device for Brake Systems
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Solution Overview
Problem
Existing brake-by-wire systems in motor vehicles face challenges in reducing size and manufacturing costs while ensuring fail-safety against leaks, particularly for autonomous driving applications.
Innovation Solution
A pressure supply device with a stepped piston and bore arrangement, actuated by an electromechanical system, which divides into two sealed pressure chambers to enhance reliability and includes a hydraulic valve for pressure control, ensuring safe and efficient brake pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-chamber pressure supply device is used, then the structure is simple, but the reliability against leaks is insufficient for autonomous driving safety requirements
Solution Approach 1:
The pressure chamber is segmented into two separate pressure chambers (first and second pressure chambers) divided by the stepped piston. This segmentation ensures that a leak in one chamber does not compromise the entire system, thereby improving reliability while maintaining a relatively simple structural design through the use of the existing piston component.
2Reliability
If the piston stage with smaller diameter is immersed to divide the pressure chamber, then the reliability is improved, but the device size increases
Solution Approach 1:
The piston stage with smaller diameter is nested within the stepped bore, utilizing the existing space efficiently. The stepped piston design allows the smaller diameter stage to immerse into the corresponding bore stage without requiring additional external space, thereby improving failure safety while minimizing increase in device volume.
Solution Approach 2:
The pressure chamber division is achieved through a dimensional change in the piston structure (stepped design with different diameters) rather than adding separate components. This allows the first and second pressure chambers to be created within the same cylindrical space, improving reliability without proportionally increasing the device's external dimensions.
3Reliability
If a sealing element is added to seal the pressure chambers, then the leak-proof performance is improved, but the manufacturing cost increases
Solution Approach 1:
The sealing function is merged with the stepped piston structure itself. The stepped piston with its different diameter stages creates natural sealing surfaces against the stepped bore, eliminating the need for separate complex sealing components. This merging of sealing functionality into the existing piston design improves leak-proof performance while keeping manufacturing costs relatively low.
4Productivity
If the pressure chamber is divided into two chambers, then the brake pressure build-up speed is improved, but the device complexity increases
Solution Approach 1:
The pressure chamber is segmented into two independent chambers that can be pressurized separately and simultaneously. This segmentation allows for faster brake pressure build-up as both chambers contribute to the overall pressure generation. The segmentation is achieved through the stepped piston structure, which maintains relatively simple geometry while enabling dual-chamber functionality for improved productivity.
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 solution improves the reliability and efficiency of brake pressure application, reducing size and manufacturing costs while maintaining safety, enabling faster brake pressure build-up without increased engine power and ensuring fail-safe operation in case of leaks.
Implementation Method 1
a sealing element is preferably provided which, when the piston stage with the smaller diameter is immersed, seals the first pressure chamber and the second pressure chamber against each other
Implementation Method 2
the second pressure chamber is preferably connectable to a pressure medium reservoir via a hydraulic valve in order to limit or reduce the pressure in the second pressure chamber
Data Source
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AI summary
The invention relates to an electrically controllable pressure provision device (5, 5'), particularly for a hydraulic motor-vehicle brake system, comprising a stepped bore (54), which is arranged in a housing (53, 21), and a piston (51), which can be actuated by an electromechanical actuator (35, 36). The piston (51), together with the housing (53, 21), delimits a pressure chamber (50). The piston (51) is constructed as a stepped piston, the smaller-diameter piston step (51') of which enters the smaller-diameter step (54') of the stepped bore after a specified actuation of the stepped piston, such that the pressure chamber (50) is subdivided into a first pressure chamber (55) and a second pressure chamber (56). The invention further relates to a brake system for motor vehicles having such a pressure provision device.