Relay Valve Control Piston Prestressing for Parking Brake Robustness
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Solution Overview
Problem
Electrically actuated parking brake systems face issues with unintended pressure buildup due to external environmental influences, such as icing or dirt, leading to increased leakage and potential unintentional actuation of the parking brake, as protective components like U-rings or sinter filters can lose functionality.
Innovation Solution
Incorporating a second elastic element that applies a prestressing force to the control piston, requiring a higher control pressure to achieve a certain output pressure, thereby enhancing robustness against pressure increases from leaks, and allowing independent movement of the control piston and sleeve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective components (U-rings, sinter filters) are provided to prevent environmental influences from penetrating the system via the vent, then protection against external influences is improved, but these components can lose functionality due to icing or dirt, causing increased dynamic pressure at the vent and potential unintentional pressure buildup in control lines
Solution Approach 1:
The second elastic element applies a prestressing force to the control piston in advance, creating a counterbalancing effect that prevents the control piston from being prematurely actuated by pressure increases caused by blocked protective components. This preliminary counter-action ensures that even if the first elastic element's function is compromised by environmental factors, the control piston remains stable.
Solution Approach 2:
The second elastic element acts as a cushioning mechanism that absorbs and compensates for pressure fluctuations and leaks in the control line before they can cause unintentional actuation of the parking brake. This beforehand cushioning protects the system against the harmful effects of protective component failure.
2Reliability
If a second elastic element is provided that applies a prestressing force to the control piston, then robustness against undesired pressure increase in control lines is improved, but device complexity increases
Solution Approach 1:
The second elastic element is integrated into the existing relay valve structure and serves multiple functions: it applies prestressing force to the control piston, compensates for pressure leaks, and works in conjunction with the first elastic element to control the valve's operation. This multi-functionality justifies the added component by providing multiple benefits within a single element.
3Adaptability or versatility
If control piston and sleeve are moved independently of one another, then the second elastic element can influence output pressure as a function of control pressure more effectively, but control mechanism complexity increases
Solution Approach 1:
The control mechanism is segmented into independently movable components: the control piston and the sleeve. This segmentation allows each component to respond to different forces and control signals independently, enabling the second elastic element to influence output pressure as a function of control pressure without being constrained by coupled movement. The segmentation simplifies the control logic despite adding mechanical components.
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 significantly increases the system's robustness against pressure leaks, reduces the risk of unintentional parking brake actuation, and ensures reliable operation even during power failures, particularly important for commercial vehicles.
Implementation Method 1
a first elastic element is provided which applies a biasing force to the sleeve in the axial direction
Implementation Method 2
a second elastic element is provided, which acts on the control piston in the axial direction with a further prestressing force
Data Source
Figure 1
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AI summary
The valve (58) has a control piston (94) and a sleeve (96), which are independently movable away from each other in an axial direction (98). The control piston and the sleeve are arranged in a housing (122) e.g. single piece housing. An elastic element (100) applies a biasing force to the sleeve in the axial direction. Another elastic element (102) applies another biasing force to the control piston in the axial direction. The elastic elements are designed as a spring. A relay control input (56) is connected with a vent (84) in a switching position. An independent claim is also included for a method for operating a relay valve.