Torque Distribution for Hydraulic Pumps in Construction Equipment
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Solution Overview
Problem
Conventional torque limiting systems for hydraulic work machines fail to accurately limit the total torque of plural variable displacement hydraulic pumps, leading to inefficiencies, excessive engine speed reduction, and vibration issues, especially during urgent loads, and cannot utilize the full preset torque effectively.
Innovation Solution
A system and method that includes an engine, variable displacement hydraulic pumps, hydraulic actuators, control levers, pressure sensing means, and torque distributing means to proportionally reduce the torque values of hydraulic pumps, ensuring the total torque does not exceed a preset limit, while maintaining user intention and preventing engine stoppages and excessive speed reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional torque limiting systems are used to limit the torque of hydraulic pumps, then the engine torque is controlled, but the total torque of plural hydraulic pumps cannot be accurately limited and the full preset torque cannot be utilized
Solution Approach 1:
The controller continuously monitors the load pressure of each hydraulic pump and the engine torque, dynamically adjusting the torque distribution among pumps based on real-time conditions. This feedback mechanism enables accurate total torque limiting while maximizing utilization of the preset torque capacity.
Solution Approach 2:
The system dynamically redistributes torque among multiple hydraulic pumps based on varying load conditions. When total torque demand exceeds the preset limit, the controller proportionally adjusts each pump's torque contribution, enabling adaptive torque management that accurately limits total torque while maintaining optimal power utilization.
2Reliability
If the torque of hydraulic pumps is limited during urgent load, then engine stoppage is prevented, but excessive engine speed reduction and vibration occur
Solution Approach 1:
The system applies differentiated torque limiting strategies to individual hydraulic pumps based on their specific load conditions. Rather than uniformly limiting all pumps, the controller selectively adjusts torque distribution, allowing pumps with lower load demands to contribute more torque, thereby preventing excessive engine speed reduction and vibration while maintaining engine stability.
3Power
If mechanical torque limiting mechanism is used for single hydraulic pump, then torque is limited, but the maximum torque set for the whole pressure regions cannot be used due to mechanical characteristic limitation
Solution Approach 1:
The system replaces mechanical torque limiting mechanisms with an electronic control system that monitors and adjusts pump torque through electronic signals. This substitution eliminates mechanical characteristic limitations, allowing the full preset torque capacity to be utilized across the entire pressure range while maintaining precise torque control.
4Power
If cross-sensing torque control of plural pumps is performed, then torque distribution is controlled, but the construction becomes complicated and total torque cannot be fully utilized
Solution Approach 1:
The controller integrates the torque control functions of multiple hydraulic pumps into a unified control system. By merging the torque distribution logic and total torque limiting functions into a single controller, the system achieves accurate total torque utilization while avoiding the complexity of separate cross-sensing control systems for each pump.
Data Source
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AI summary
A system and method of controlling torque of plural variable displacement hydraulic pumps (2,3) in construction equipment are provided, which can control torque of the variable displacement hydraulic pumps (2,3) so that the total amount of torque of the hydraulic pumps does not exceed the preset amount of torque by presetting the torque so that the engine (1) does not stop even at maximum load of the hydraulic pumps (2,3) or by presetting the speed of the engine (1) or the used torque of the hydraulic pumps (2,3) in consideration of the fuel economy or working speed. The system includes an engine (1), at least two variable displacement hydraulic pumps (2,3), hydraulic actuators (5,6), control levers (7,8) generating manipulation signals, control lever sensing means (12,13) detecting the manipulation amounts of the control levers, hydraulic pump pressure sensing means (9,10) detecting load pressures of the hydraulic pumps (2,3), maximum torque setting means (11) setting the total torque (Tmax) inputted to the hydraulic pumps, desired flow rate computing means computing flow rates of the hydraulic pumps, expected torque computing means computing (16,17) expected torque values (Te1,Te2) of the hydraulic pumps (2,3), torque distributing means (18) distributing torque values of the hydraulic pumps, limited flow rate computing means computing the flow rates of the hydraulic pumps, and output means (21,22) outputting control signals to regulators (23,24).