Hydrostatic Control Circuit Power Failure State Retention
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Solution Overview
Problem
Existing hydrostatic control circuits for commercial vehicle steering systems fail to maintain operational modes during power failures, requiring manual intervention to ensure safety and functionality.
Innovation Solution
The control circuit incorporates an electromagnetically controlled and latched changeover valve that retains the last environmental condition, ensuring the system remains in its previous state during power failures, and includes additional features like non-return valves and pressure-controlled valves to manage hydraulic fluid exchange and pressure limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrically controlled solenoid valve is used to block the return line, then the hydraulic cylinder can be actuated during normal operation, but the system loses its last operational state during power failures
Solution Approach 1:
The latching mechanism is activated in advance during normal operation to store the last operational state. When power fails, this pre-stored state automatically maintains the system in its previous configuration without requiring real-time power supply, thus resolving the contradiction between reliability during power failure and device complexity.
2Reliability
If the return line is opened to drain residual hydraulic fluid during power failure, then safety is improved, but the system loses the ability to maintain its operational mode
Solution Approach 1:
The latching mechanism captures and stores the last operational state before power failure occurs. This preliminary action preserves the environmental condition information that would otherwise be lost when the return line is opened for safety draining, allowing the system to resume its previous mode after power restoration.
Solution Approach 2:
The latching mechanism acts as an intermediary between the hydraulic circuit and the power supply system. It decouples the memory function from the power supply, allowing the system to maintain its state information independently of electrical power, thus preventing information loss while still allowing safety draining.
3Adaptability or versatility
If check valves are used to allow bidirectional fluid flow, then operational flexibility is improved, but uncontrolled fluid loss can occur during power failures
Solution Approach 1:
The latching mechanism provides feedback control for the check valves based on the stored last operational state. During power failure, this feedback control prevents uncontrolled opening of check valves, thereby stopping hydraulic fluid loss while still allowing the check valves to provide operational flexibility when power is available.
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 ensures the hydrostatic control circuit maintains functionality and safety by retaining the last environmental condition during power failures and effectively managing hydraulic fluid exchange, enhancing reliability and operational stability.
Implementation Method 1
an electrically controlled solenoid valve which, in its current-carrying operating position, blocks the return line to the tank
Implementation Method 2
in the de-energized position (e.g. in the event of a power failure) is switched due to the force of a spring into a position in which the return line is open
Implementation Method 3
the one branch line due to the force of a spring closing towards one chamber and the other branch line has a check valve closing due to the force of another spring towards the other chamber
Data Source
Figure 1
Figure 2
AI summary
The circuit has an exhibiting tank (10) filled with hydraulic fluid. Two terminals (21, 22) are fixed with an exhibiting reversible hydraulic pump (20) and chambers (32, 33). A double acting hydraulic cylinder (30) e.g. synchronism cylinder or differential cylinder, is arranged on trunk lines (41, 42). A return-flow pipe (50) with an electrical steered magnetic valve (60) is provided in the tank and connected to the trunk line over branch lines (51, 52). The chambers and the branch lines are closed by force of springs (511, 521).