Hydraulic Drive System Flow Rate Distribution Control
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Solution Overview
Problem
Existing hydraulic systems for construction machines fail to accurately match the operating speed of multiple hydraulic actuators with operator intent, leading to decreased operability due to inconsistent flow rate distribution when multiple actuators are operated simultaneously.
Innovation Solution
A drive system with a controller that computes and adjusts distribution flow rates among hydraulic actuators to match demanded flow rates, ensuring the ratio of distribution flow rates equals the ratio of demanded flow rates, even when these exceed the maximum delivery capacity of hydraulic pumps, by using a flow rate distribution section and pump allocation computing section to manage the connection between hydraulic pumps and actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic pumps are connected to hydraulic actuators based on predetermined connection patterns, then the system structure is simple, but the supply flow rate does not match the demanded flow rate when multiple actuators operate simultaneously
Solution Approach 1:
The patent implements dynamic connection patterns where the connection between hydraulic pumps and actuators is not fixed but changes based on real-time operation conditions. The controller dynamically determines which pumps connect to which actuators based on demanded flow rates and current system state, allowing the system to adapt to varying operational requirements and maintain optimal performance across different work scenarios
Solution Approach 2:
The system changes the connection configuration parameter based on flow rate demands. When multiple actuators operate simultaneously, the controller adjusts which pumps are connected to which actuators, effectively changing the system's connection topology to match the demanded flow rate distribution, thereby resolving the contradiction between simple structure and operational accuracy
2Productivity
If the number of hydraulic pumps is limited, then the system cost is reduced, but the maximum delivery amount is insufficient to meet the demanded flow rate of all actuators simultaneously
Solution Approach 1:
The patent implements dynamic pump allocation where a limited number of pumps are dynamically assigned to different actuators based on real-time demands. The controller continuously monitors the operation state of multiple actuators and dynamically determines which pumps should supply which actuators, allowing the same physical pumps to serve different actuators at different times, thereby satisfying the flow rate demands of multiple actuators simultaneously with fewer physical pumps
Solution Approach 2:
The system employs periodic redistribution of pump resources among actuators. When multiple actuators require flow simultaneously, the controller periodically switches the connection patterns, allocating pumps to actuators with higher priority or greater flow demand at different time intervals, ensuring that overall productivity requirements are met despite having fewer pumps than actuators
3Ease of operation
If hydraulic pumps are allocated based on predetermined priorities, then the control logic is simple, but the operating speed of actuators does not match the operator's intention when multiple actuators are operated
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the actual flow rates supplied to actuators and compares them with the demanded flow rates based on operator input. The controller uses this feedback information to dynamically adjust the connection patterns between pumps and actuators, ensuring that the actual operating speeds of actuators match the operator's intentions, thereby resolving the contradiction between simple control logic and accurate speed control
Solution Approach 2:
The system replaces traditional mechanical priority-based allocation with electronic computation and control. Instead of using fixed mechanical connections with predetermined priorities, the patent uses electronic sensors, controllers, and solenoid valves to dynamically compute and implement optimal pump-actuator connections based on real-time flow rate demands, achieving much more precise control over actuator speeds
Data Source
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AI summary
A drive system for a construction machine capable of appropriately controlling a distribution flow rate to each hydraulic actuator and improving operability by an operator is provided. A flow rate distribution section 32 that computes a distribution flow rate of a hydraulic fluid supplied to each of a plurality of hydraulic actuators 4-7 on the basis of a demanded flow rate, sets, within a distributable region set for computing a range of a distributable flow rate that is a flow rate of the hydraulic fluid suppliable to each of at least two hydraulic actuators driven by a combined operation among the plurality of hydraulic actuators 4-7 from a plurality of hydraulic pump devices 10a-10d for the at least two hydraulic actuators, a distribution region for computing a range of the distribution flow rate of the hydraulic fluid actually supplied to each of the at least two hydraulic actuators, and computes the distribution flow rate in such a manner that the distribution flow rate falls within the distribution region and a ratio among the distribution flow rates of the plurality of hydraulic actuators 4-7 is equal to a ratio among the demanded flow rates of the plurality of hydraulic actuators 4-7.