Torque Control for Variable Displacement Pumps
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Solution Overview
Problem
Hydraulic systems with variable displacement pumps face challenges in managing torque demand, as the torque required to drive the pump can exceed the capacity of the power source, especially under varying operating conditions such as different pressures and loads.
Innovation Solution
A torque control system that adjusts the displacement volume of the variable displacement pump by changing the stroke length of the pistons in response to changes in outlet pressure, using a control system with a torque control valve and a swash plate position control piston to maintain a constant torque limit across a range of pressures, speeds, and oil temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump displacement volume is increased to achieve higher flow rates, then the productivity is improved, but the torque demand exceeds the power source capacity
Solution Approach 1:
The pump system dynamically adjusts displacement volume based on operating conditions. The control system continuously monitors outlet pressure and automatically modifies piston stroke length to maintain optimal balance between flow output and torque demand, allowing the system to adapt to varying load requirements without exceeding power source capacity
Solution Approach 2:
The system changes the displacement volume parameter in response to outlet pressure variations. By modifying the piston stroke length parameter, the pump can deliver high flow at low pressure while automatically reducing displacement at high pressure to prevent torque overload, thus resolving the contradiction between productivity and force requirements
2Power
If the pump operates at high pressure to meet load demands, then the power output is improved, but the torque required exceeds the power source capacity
Solution Approach 1:
The control system employs feedback from outlet pressure sensing to automatically adjust pump displacement. When outlet pressure indicates high load conditions, the system reduces displacement volume to limit torque demand, thereby maintaining power output within the power source capacity while still meeting hydraulic power requirements
Solution Approach 2:
The pump operates dynamically by continuously adjusting displacement volume based on real-time pressure conditions. This dynamic adjustment allows the system to deliver required hydraulic power at varying pressures without exceeding the maximum torque capacity of the power source
3Force
If the pump displacement is reduced to limit torque demand, then the torque capacity is preserved, but the output flow decreases
Solution Approach 1:
The system strategically changes displacement volume parameter based on operating pressure. At low pressure conditions, the pump operates at high displacement to maximize flow output and productivity. When pressure increases indicating high load, the system reduces displacement to preserve torque capacity, thus optimizing both flow and force across different operating conditions
Data Source
AI summary
The present invention relates to a hydraulic pump system including a variable displacement pump that generates an outlet pressure. The hydraulic pump system also includes a control system that decreases a displacement volume of the variable displacement pump in response to an increase in the outlet pressure and increases a displacement volume of the variable displacement pump in response to a decrease in the outlet pressure.