Hydraulic Pump Control for Accurate Construction Machine Actuation
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Solution Overview
Problem
Existing construction machines with machine control (MC) functions face accuracy issues when non-target hydraulic actuators are operated, leading to reduced responsiveness and control accuracy due to insufficient hydraulic pump delivery rates and complex flow dividing and combining, particularly during operations like excavation for foundation.
Innovation Solution
A construction machine with a dual hydraulic pump system, including a controller that computes and adjusts the supply flow rates and target speeds of hydraulic actuators based on sensor inputs, ensuring optimal operation even when non-target actuators are manually operated, by limiting speeds and combining flow rates to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum delivery rate of a hydraulic pump is insufficient relative to the total target flow rate of multiple hydraulic actuators, then another hydraulic pump's delivered fluid is combined to compensate, but the MC control becomes more susceptible to load pressure influence and control accuracy lowers
Solution Approach 1:
The hydraulic system is segmented into multiple independent hydraulic pumps, each responsible for specific hydraulic actuators. This segmentation prevents flow dividing and combining between different pumps, thereby reducing the influence of load pressure on flow rate control and maintaining MC control accuracy even when one pump's delivery rate is insufficient.
Solution Approach 2:
A flow rate adjusting mechanism is introduced as an intermediary between the hydraulic pump and the hydraulic actuators. This mechanism actively adjusts and balances the flow rate to each actuator based on their individual requirements, compensating for the insufficient delivery rate of a single pump without requiring flow combining from multiple pumps, thus maintaining control accuracy.
2Adaptability or versatility
If multiple hydraulic actuators connected to the same hydraulic pump act simultaneously, then the system can perform multiple operations, but the delivered fluid readily flows into actuators with low load pressure and flow dividing/combining increases complexity
Solution Approach 1:
Each hydraulic actuator is connected to the hydraulic pump through an independent hydraulic line with its own flow rate adjusting mechanism. This segmentation allows multiple actuators to operate simultaneously without flow interfering between them, while keeping each hydraulic line relatively simple and avoiding complex flow dividing and combining.
Solution Approach 2:
The flow rate to each hydraulic actuator is dynamically adjusted based on real-time load pressure and flow rate requirements. The flow rate adjusting mechanisms respond to changing operational conditions, maintaining optimal flow distribution without requiring fixed complex hydraulic line configurations.
Data Source
AI summary
There is provided a construction machine including first and second hydraulic actuators that are driven by first and second hydraulic pumps, respectively, and drive a front work implement, a third hydraulic actuator driven by the second hydraulic pump, solenoid valves that control a hydraulic fluid supplied to the second hydraulic actuator, an operation device that operates the front work implement, and a controller that controls the solenoid valves and the first and second hydraulic pumps on the basis of the distance between the front work implement and a target construction face and an operation signal. The controller computes an upper limit speed of the second hydraulic actuator on the basis of the flow rate difference between the maximum delivery rate of the second hydraulic pump and a supply flow rate supplied to the third hydraulic actuator, computes a target speed of the second hydraulic actuator while limiting, by the upper limit speed, a required speed of the second hydraulic actuator according to the operation signal, and controls the solenoid valves and the second hydraulic pump according to the target speed.