Open-Center Hydraulic Circuit for Smooth Material Handler Motion
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Solution Overview
Problem
Existing hydraulic systems in material handlers, such as excavators, lack the ability to provide consistent movement and precision during pick and place tasks due to open-center hydraulics, leading to jerking motions and potential load dropping.
Innovation Solution
A control system with a joystick, electronic control unit (ECU), and hydraulic circuit that includes directional and pressure buildup valves, utilizing solenoids and biasing elements to maintain consistent movement and pressure thresholds, regardless of load conditions, through a binary or analog mode of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open-center hydraulics is used in material handlers, then the system structure is simple, but the movement consistency and precision deteriorate causing jerking motions and potential load dropping
Solution Approach 1:
The patent changes the hydraulic system parameters by introducing a pressure buildup valve that maintains a minimum pressure threshold in the open-center hydraulic system. This allows the system to retain its simple open-center structure while achieving consistent movement by preventing pressure fluctuations that cause jerking motions.
Solution Approach 2:
The pressure buildup valve acts as an intermediary component between the hydraulic pump and the directional control valve. It mediates the pressure fluctuations in the open-center system by maintaining a minimum pressure level, thereby eliminating jerking motions without requiring a complete system redesign.
2Manufacturing precision
If pressure buildup valve is added to maintain consistent movement, then movement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts only the essential function needed to solve the problem - a pressure buildup valve that maintains minimum pressure - rather than implementing a complete closed-center hydraulic system. This minimal intervention approach achieves movement precision while adding only one component to the existing simple hydraulic circuit.
3Measurement precision
If solenoids act in opposition to biasing elements for directional control, then control precision improves, but device complexity increases
Solution Approach 1:
The patent uses asymmetric actuation where solenoids act in opposition to biasing elements (springs) on the directional control valve. This asymmetric design allows precise control of the valve spool position by balancing electromagnetic force against spring force, achieving accurate directional control while maintaining a relatively simple actuation mechanism.
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
Ensures consistent and precise control of hydraulic cylinders, minimizing jerking motions and enhancing precision in material handling tasks by adjusting pressure thresholds based on load conditions.
Implementation Method 1
A pair of solenoids controlled by the ECU may act in opposition to each of the pair of biasing elements of the directional control valve to move the directional control valve to the extension position or the retraction position
Implementation Method 2
The directional control valve may have a pair of biasing elements, such as spring, maintaining the directional control valve in the central position
Implementation Method 3
A constrictive solenoid may be controlled by the ECU and when activated causes the pressure building valve to move towards the constrictive position whereby the constrictive passageway increases pressure in the central passageway of the directional control valve
Data Source
AI summary
A computer-implemented method and/or system for controlling a material handler comprises: processing, by an electronic control unit (ECU), a plurality of electronic input signals from at least one joystick; determining an adjustment for at least one of a pair of solenoids based on at least the plurality of electronic input signals from the joystick; controlling the pair of solenoids by the ECU and each solenoid acting in opposition to each of a pair of biasing elements of an open-center directional control valve to move the directional control valve to an extension position or a retraction position from a central position; determining a setpoint buildup pressure for a central passageway of the directional control valve; and actuating a constrictive solenoid of a pressure buildup valve to constrict the central passageway based on the setpoint buildup pressure whereby the constrictive passageway increases a pressure in the central passageway of the directional control valve.