Variable Hydraulic Pump Control for Single and Combined Actuator Demand
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Solution Overview
Problem
Existing hydraulic pump control systems for construction machines, like hydraulic excavators, face challenges in maintaining optimal driving speed for hydraulic actuators during both single and combined operations, leading to insufficient or excessive delivery flow rates, resulting in energy loss.
Innovation Solution
A construction machine equipped with a variable displacement hydraulic pump, flow control valves, operation devices, and a controller that computes and adjusts target displacement volumes to ensure suitable actuator speeds while minimizing the delivery flow rate, by selecting either the sum total or maximum value of computed displacement volumes based on operation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the maximum tilting amount is increased to ensure sufficient delivery flow rate during combined operation of multiple hydraulic actuators, then the delivery flow rate becomes sufficient for combined operation, but the delivery flow rate becomes excessive during single operation of individual actuators, resulting in enlarged energy loss
Solution Approach 1:
The patent applies dynamics by making the pump displacement variable based on operating conditions. The control unit dynamically adjusts the pump displacement according to the operation amounts of multiple actuators, switching between fixed displacement and variable displacement modes. This allows the system to optimize delivery flow rate for each specific operating scenario, preventing both insufficiency during combined operation and excessive flow during single actuator operation, thereby reducing energy loss.
Solution Approach 2:
The patent changes the parameter of pump displacement based on operating conditions. The control unit calculates required flow rates for each actuator and determines the appropriate pump displacement setting. By adjusting this key parameter according to whether actuators are operating individually or in combination, the system achieves optimal flow rate matching and minimizes energy loss from excessive delivery flow.
2Speed
If the maximum tilting amount is set to the optimum value for each hydraulic actuator, then the optimum maximum driving speed is obtained during single operation, but the delivery flow rate becomes insufficient during combined operation of multiple actuators, preventing attainment of optimum driving speed
Solution Approach 1:
The patent implements feedback control where the control unit continuously monitors the operation amounts of multiple hydraulic actuators and adjusts the pump displacement accordingly. By calculating the required flow rates based on actual actuator operation and feeding this information back to the pump control, the system ensures sufficient delivery flow rate during combined operation while maintaining optimum driving speeds for individual actuators.
Solution Approach 2:
The patent makes the hydraulic pump system universal by enabling it to handle both single actuator operation and combined multi-actuator operation effectively. Through variable displacement control, the single pump can adapt its output to meet the demands of different operating scenarios, providing both optimum speed for individual actuators and sufficient total flow rate for combined operations.
3Quantity of substance
If the delivery flow rate of the hydraulic pump is increased to ensure sufficient flow for combined operation, then the flow rate requirement is met, but the energy loss is enlarged due to excessive flow during single operation
Solution Approach 1:
The system uses dynamic displacement control to match pump output with actual demand. Rather than maintaining a fixed high flow rate, the pump displacement is continuously adjusted based on the combined operation amounts of all actuators. This dynamic adaptation ensures sufficient flow during combined operation while reducing flow and energy consumption during single actuator operation.
Solution Approach 2:
The patent changes the pump displacement parameter according to operating conditions to optimize energy efficiency. The control unit calculates the minimum required flow rate based on current actuator demands and sets the pump displacement accordingly. This parameter adjustment prevents energy waste from excessive flow delivery while ensuring adequate flow availability when multiple actuators operate simultaneously.
Data Source
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AI summary
Provided is a construction machine capable of driving each hydraulic actuator at a suitable speed while suppressing delivery flow rate of a hydraulic pump, both at a single operation time of driving each hydraulic actuator respectively singularly and at a combined operation time of simultaneously driving a plurality of hydraulic actuators. A controller is configure to compute a first required pump flow rate for each of operation amounts of a plurality of operation devices, compute a second required pump flow rate greater than the first required pump flow rate for the same operation amount for each of the operation amounts of the plurality of operation devices, select as a final required pump flow rate either smaller one of a sum total value of the first required pump flow rates computed for the operation amounts of the plurality of operation devices and a maximum value of the second required pump flow rates computed for the operation amounts of the plurality of operation devices, and control a regulator in such a manner that the delivery flow rate of the hydraulic pump and the final required pump flow rate will be equal.