Hydraulic Control Device With AND Logic Element
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Solution Overview
Problem
Existing hydraulic control systems face issues with inappropriate heating and instability due to high control pressures required for maintaining a floating position, and they are often complex and expensive, especially when using four-position proportional directional slides.
Innovation Solution
A hydraulic control system utilizing a three-position proportional directional slide with an AND logic element that connects control pressures to load-holding valves only when both proportional magnets are energized simultaneously, reducing the current required and preventing heating issues, while maintaining stability and sensitivity through moderate control pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high control pressure is applied to open load-holding valves in floating position, then the valves can be fully opened, but the proportional magnets generate excessive heat leading to inappropriate heating
Solution Approach 1:
The patent introduces a logic element as an intermediary between the proportional magnets and the load-holding valves. This logic element receives control pressure signals from both proportional magnets and only transmits the high control pressure to the valves when both signals are present simultaneously. This mediator allows the system to use low control pressures for signaling while maintaining the ability to open valves fully when needed, thereby resolving the contradiction between reliable valve opening and excessive heat generation in proportional magnets.
2Temperature
If control ratio of load-holding valves is increased to enable operation with low control pressures, then heating from proportional magnets is reduced, but the valves open too quickly or abruptly during directional control
Solution Approach 1:
The logic element serves as a mediator that decouples the control ratio setting from the actual valve opening behavior. By using a logic element with specific pressure thresholds, the system can employ a control ratio that prevents excessive heating while the logic element itself ensures stable and controlled valve opening by requiring simultaneous presence of both control pressure signals before transmitting the high pressure needed for smooth valve operation.
3Adaptability or versatility
If a four-position proportional directional slide is used to enable floating position and hydraulic blocking, then functional requirements are met, but the device becomes structurally complex and expensive
Solution Approach 1:
The patent segments the hydraulic control system into distinct functional components: a simple three-position proportional directional slide for basic directional control, separate load-holding valves for maintaining position, and a logic element for enabling the floating position function. This segmentation allows each component to perform its specific function with simple structure, while the combination provides the complex four-position functionality, thereby resolving the contradiction between functional versatility and structural simplicity.
Solution Approach 2:
The logic element serves multiple functions: it enables the floating position by transmitting control pressure to open both load-holding valves simultaneously, maintains hydraulic blocking by preventing pressure transmission when only one proportional magnet is activated, and provides a logical AND function for safe operation. This multi-functionality of a single simple component achieves the versatility of a complex four-position slide without the structural complexity and cost.
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 system achieves stable and sensitive control behavior with reduced heating problems and lower current consumption, allowing for efficient operation of load-holding valves without the need for complex or expensive components.
Implementation Method 1
both proportional magnets must be supplied with relatively high current up to the maximum at the same time and at the same time
Implementation Method 2
a control pressure is applied to only one load-holding valve on its control side, which control pressure is tapped off from the pressurized working line
Implementation Method 3
the control sides of the load-holding valves remain pressure-relieved and shut off the load-holding valves
Data Source
Figure 1
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AI summary
In the control pressure circuit (10) of a hydraulic control (H) of a double-acting hydraulic actuator (V), with a three-position proportional direction slide (W) between a pressure source/tank arrangement (P, R) and working lines (A, B) containing load-holding valves (11, 12), a hydraulic AND logic element (L) is provided, which, when the float position is set by simultaneously energizing two proportional solenoids (4, 6), connects a control pressure supply (Z) to the control sides (47, 48) of the load-holding valves (11, 12). The logic element (L) contains two actuating pistons (54, 56) connected in series, which, when two control pressures are applied in control lines (1, 2), unlock a check valve (26).