Bistable Valve Self-Retaining Device for Parking Brake Stability
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Solution Overview
Problem
The existing parking brake systems in commercial vehicles can spontaneously engage or disengage due to defects, leading to unsafe conditions while driving and difficulties in towing, as they lack stability in their open state.
Innovation Solution
A bistable valve with a self-retaining device, comprising a movable sliding element, a fixed detent, and a rotatable deep-locking element, actuated by an electrically or pneumatically controllable coil or piston, which maintains two stable switching states for the parking brake, ensuring it remains open even in case of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-loaded brake cylinder is used to ensure the parking brake is stable when closed, then the parking brake reliability is improved, but the parking brake cannot remain stable when open and may spontaneously engage due to defects
Solution Approach 1:
The patent transforms the static spring-loaded brake cylinder into a dynamic bistable valve system with two stable equilibrium positions (open and closed states). The valve body with movable sealing element and detent mechanism allows the system to dynamically switch between and maintain either state, preventing spontaneous engagement while keeping both states stable.
Solution Approach 2:
The brake system is segmented into two independent stable states controlled by the bistable valve. The valve separates the pressure supply and release pathways, allowing independent control of the open and closed states. This segmentation ensures that defects in one state do not automatically trigger the other state, solving the spontaneity problem.
2Reliability
If the parking brake is designed to be stable when closed, then safety when parked is improved, but the system becomes vulnerable to spontaneous engagement while driving due to electronic or mechanical defects
Solution Approach 1:
The bistable valve incorporates a detent mechanism with latching elements that preemptively secure the valve in either the open or closed position. This mechanical latching provides a cushioning effect against defects, ensuring that even if electronic controls fail, the valve remains locked in its current state and cannot spontaneously switch, preventing harmful spontaneous braking.
3Device complexity
If a traditional monostable valve is used to control the parking brake, then the structure is simple, but the system lacks stability in the open state and cannot prevent spontaneous engagement
Solution Approach 1:
The bistable valve employs a nested structure where the movable sealing element is housed within the valve body, and the detent mechanism with latching elements is integrated into the valve assembly. This nested design achieves bistability without requiring completely separate mechanisms, maintaining reasonable structural simplicity while providing the required dual-state stability and defect tolerance.
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 bistable valve ensures the parking brake remains stable and open during vehicle operation, preventing spontaneous engagement and facilitating safe driving and towing by maintaining the desired operational state even in the event of system failures.
Implementation Method 1
an actuating element designed as an electrically controllable magnetic coil for actuating the self-retaining device
Implementation Method 2
an actuating element designed as a pneumatically controllable pneumatic piston for actuating the self-retaining device
Data Source
Figure 1~2
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AI summary
The invention relates to a bistable valve (10) having a self-retaining device (12). The invention provides that the self-retaining device (12) comprises a movable sliding element (14), a stationary latch (16), and a deep latching element (18) being pivotable relative to the sliding element (14) and the latch (16). The invention further relates to a method for actuating a parking brake system (24) having a bistable valve (10) comprising a self-retaining device (12).