Hydraulic Pump Allocation Across Circuits to Cut Pressure Drop
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Solution Overview
Problem
Existing hydraulic power systems experience pressure drop losses due to flow sharing between hydraulic circuits, which affects the efficiency and performance of hydraulic machines like excavators.
Innovation Solution
A system where each hydraulic pump is exclusively associated with one hydraulic circuit, using variable displacement pumps and open center valves for precise flow control, and a control unit determines the required flow and allocates pumps based on operator input and load conditions to minimize pressure drop losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydraulic pumps supply flow to multiple hydraulic circuits through flow sharing, then the system can serve multiple circuits with fewer pumps, but pressure drop losses increase and hydraulic efficiency decreases
Solution Approach 1:
The hydraulic system is segmented into dedicated pump-circuit pairs, where each pump is exclusively assigned to supply one hydraulic circuit. This segmentation eliminates flow sharing between circuits, preventing pressure drop losses that occur when multiple circuits draw from a common pump source, thereby improving hydraulic efficiency while maintaining the ability to serve multiple circuits.
Solution Approach 2:
The system dynamically associates pumps with hydraulic circuits based on real-time flow requirements and load conditions. The control unit monitors hydraulic flow demands and reconfigures pump-circuit associations as needed, allowing the system to adapt to varying operational conditions while maintaining optimal efficiency by assigning pumps to circuits that require the most hydraulic power at any given moment.
2Loss of energy
If hydraulic pumps are exclusively associated with single hydraulic circuits, then pressure drop losses are reduced and hydraulic efficiency is improved, but the system complexity and control requirements increase
Solution Approach 1:
The control unit serves multiple functions: it monitors hydraulic flow requirements, determines optimal pump-circuit associations, controls variable displacement pumps, and manages control valve positioning. By consolidating these control functions into a single multi-functional control unit, the system achieves the benefits of exclusive pump-circuit associations without proportionally increasing overall system complexity.
Solution Approach 2:
The system incorporates sensors that automatically detect overrunning load conditions and provide feedback to the control unit, which then autonomously adjusts pump-circuit associations and flow distribution. This self-service capability reduces the need for complex manual control mechanisms while maintaining optimal hydraulic efficiency through automatic adaptation to load conditions.
3Productivity
If variable displacement pumps are used for precise flow control, then hydraulic flow efficiency is improved and engine speed is maintained, but the pump complexity and manufacturing cost increase
Solution Approach 1:
Variable displacement pumps enable precise flow control by dynamically changing the displacement parameter of the pump mechanism. This allows the system to deliver exactly the hydraulic flow required by each circuit while maintaining constant engine speed, improving overall efficiency. The ability to adjust displacement rather than using fixed displacement pumps with flow control valves simplifies the overall hydraulic architecture despite the increased complexity of the pump mechanism itself.
Data Source
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AI summary
A system (116) for providing hydraulic power to a hydraulic system of a machine allows assigning individual hydraulic pumps (132-140B) to different hydraulic circuits (160-170) of the hydraulic system. The system (116) reduces flow sharing between the different hydraulic circuits (160-170) to avoid pressure drop losses. A plurality of control valves (142-150B) regulate the flow to the different circuits and may be switched to selectively associate one or more hydraulic pumps (132-140B) to a particular hydraulic circuit. The distribution of the pumps may be determined based on priorities of the different hydraulic circuits and the flow required by each circuit. The flow rate for each hydraulic circuit is controlled by the displacement of the associated hydraulic pumps.