Hydraulic Boom Control Using Gravity-Driven Attachment Flow
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Solution Overview
Problem
Existing hydraulic control systems for machines with pivotable booms and attachments, such as wheel loaders and skid steer loaders, inefficiently manage the synchronized movement of the boom and attachment during lowering operations, leading to suboptimal loading cycles.
Innovation Solution
A hydraulic control system that includes a lowering manifold with a pressure sensor and directional control valves to regulate the flow of hydraulic fluid based on pressure values, allowing synchronized movements of the boom and attachment by regenerating hydraulic fluid from the piston side to the rod side of the boom hydraulic cylinder, thus optimizing the loading cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydraulic pump supplies flow for both boom lowering and attachment movement simultaneously, then both functions can be performed, but the pump power is divided between them reducing overall efficiency
Solution Approach 1:
The invention converts the harmful effect of gravity (which causes uncontrolled boom lowering) into a beneficial force by allowing the boom weight to drive the hydraulic cylinder and generate fluid flow. This gravity-driven flow is directed through the lowering manifold to actuate the attachment, thereby converting the problematic gravitational force into useful work that synchronizes attachment movement with boom lowering without requiring additional pump power.
Solution Approach 2:
The system enables self-service by allowing the boom's own gravitational potential energy to power the attachment movement during lowering operations. The hydraulic fluid generated by the boom cylinder's downward motion automatically flows through the lowering manifold to drive the attachment cylinder, creating a self-sustaining system where the boom's descent provides the energy needed for synchronized attachment actuation.
2Speed
If the pump flow rate is used for boom lowering, then the boom can be lowered, but the flow available for attachment movement is reduced
Solution Approach 1:
The invention merges the hydraulic flow paths by combining the pump-supplied flow with the gravity-generated flow from the boom cylinder into a single unified system. The lowering manifold acts as a merging point where both flow sources are combined and directed to the attachment cylinder, allowing the attachment to receive sufficient hydraulic flow for high-speed movement while the boom simultaneously lowers using its own gravity-driven flow.
3Productivity
If synchronized movement of boom and attachment is achieved, then loading cycle efficiency improves, but the control system complexity increases
Solution Approach 1:
The lowering manifold serves as an intermediary device that automatically coordinates between the boom cylinder and attachment cylinder. Instead of requiring complex electronic sensors, controllers, and feedback systems to achieve synchronization, the manifold passively mediates the hydraulic flow based on the boom's position and movement, automatically directing the appropriate flow rates to maintain synchronized operation throughout the loading cycle.
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
Enhances the speed and efficiency of loading cycles by ensuring synchronized movements of the boom and attachment, allowing the hydraulic pump's power to be fully utilized for attachment rotation without dividing it between boom lowering and attachment movement.
Implementation Method 1
A pressure sensor is provided that is configured to detect a (piston side) pressure value of hydraulic fluid and configured to be connected to the piston side of the at least one boom hydraulic cylinder
Implementation Method 2
a lowering manifold (i.e. an arrangement of hydraulic valves and hydraulic lines connecting them internally) is controlled to determine, during a 'return movement state', a meter-out flow rate of the flow of hydraulic fluid from the piston side of the boom hydraulic cylinder
Data Source
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AI summary
The invention relates to a hydraulic control system (24) for a machine (1), wherein the machine has a hydraulic pump (22), a tank (26), at least one boom hydraulic cylinder (12) and at least one attachment hydraulic cylinder (14), comprising an attachment directional control valve (30) configured to be connected to the hydraulic pump (22) and to piston and rod sides (17, 19) of the at least one attachment hydraulic cylinder (14); a lowering manifold (40) configured to be connected to piston and rod sides (16, 18) of the at least one boom hydraulic cylinder (12); a pressure sensor (48) configured to detect a pressure value of hydraulic fluid and configure to be connected to the piston side (16) of the at least one boom hydraulic cylinder; and a control device (36) configured to control the attachment directional control valve and the lowering manifold and configured to receive the pressure value; wherein, when the hydraulic control system (24) is connected to the hydraulic pump (22), the at least one boom hydraulic cylinder (12) and the at least one attachment hydraulic cylinder (14), the control device is configured, during a return movement state: to determine, based on the pressure value, a meter-out flow rate of the flow of hydraulic fluid from the piston side (16) of the boom hydraulic cylinder to the rod side (18) of the boom hydraulic cylinder, and to control the attachment directional control valve (30), such that hydraulic fluid from the hydraulic pump (22) is directed into the piston side (17) or the rod side (19) of the attachment hydraulic cylinder (14), wherein a position of a spool of the attachment directional control valve is controlled based on said meter-out flow rate.