Torque Allocation for Variable Displacement Hydraulic Pumps
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Solution Overview
Problem
Existing hydraulic flow control systems in construction equipment, such as skid-steer loaders, face challenges in allocating torque effectively across pumps and couplings to prevent exceeding torque tolerance limits, which limits the available torque for hydraulic output and can lead to system inefficiencies.
Innovation Solution
A hydraulic system with variable and fixed displacement pumps, monitored by displacement and pressure sensors, and controlled by a programmed logic controller to allocate engine torque optimally across couplings, reducing pump displacement when torque limits are approached, ensuring each coupling operates within its design limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple variable displacement pumps are used in a hydraulic system to provide power for ground drive and accessory functions, then the available torque for hydraulic output is increased, but the risk of exceeding coupling torque tolerance limits increases
Solution Approach 1:
The system employs variable displacement pumps that can dynamically adjust their displacement to optimize torque distribution. The controller continuously monitors coupling torque loads and dynamically reduces pump displacement when torque limits are approached, allowing the system to maximize power utilization while maintaining reliability through real-time adaptive control.
Solution Approach 2:
The system incorporates torque sensors on each coupling and a controller that continuously monitors coupling torque loads. When the torque load on any coupling approaches its tolerance limit, the controller provides feedback to reduce the displacement of affected pumps, ensuring torque distribution remains within safe limits while maximizing overall system power utilization.
2Reliability
If pump displacement is reduced to prevent exceeding coupling torque limits, then coupling reliability is maintained, but the hydraulic output power is reduced
Solution Approach 1:
Rather than statically reducing pump displacement, the system dynamically adjusts displacement based on real-time torque conditions. The variable displacement pumps can operate at full capacity when torque limits are not approached and only reduce displacement when necessary, maximizing power utilization while maintaining coupling reliability through adaptive control.
Solution Approach 2:
The system changes the displacement parameter of variable pumps based on monitored torque conditions. By continuously adjusting pump displacement in response to coupling torque loads, the system optimizes the balance between power output and coupling protection, ensuring maximum hydraulic power is delivered within safe torque limits.
3Productivity
If a controller continuously monitors and adjusts pump displacement to optimize torque allocation, then system efficiency is improved, but the device complexity increases
Solution Approach 1:
The controller serves multiple functions: it monitors torque loads on all couplings, determines which pumps need displacement adjustment, calculates optimal displacement reductions, and controls multiple variable displacement pumps. This multi-functionality justifies the added complexity by providing comprehensive torque management that maximizes system efficiency and prevents coupling failures.
Solution Approach 2:
The controller implements continuous feedback monitoring of coupling torque loads and automatically adjusts pump displacement in real-time. This closed-loop control system optimizes torque allocation across the hydraulic system, improving efficiency by preventing both underutilization and overloading of couplings, while the automated nature of the feedback control minimizes the need for complex manual intervention systems.
Data Source
AI summary
Disclosed is a system for allocating torque, supplied in one embodiment by an engine, to multiple variable and fixed displacement pumps coupled together in a series by coupling elements interspersed between the pumps. A controller is included which monitors the torque applied to each coupling element. The controller automatically varies displacement in one or more of the variable displacement pumps to prioritize and allocate torque to optimize available torque while keeping the torque applied to each coupling element within the torque limit for that particular coupling element.