Hydraulic Work Machine Flow Control for Manual and Automatic Modes
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Solution Overview
Problem
Existing work machines, such as hydraulic excavators, face challenges in maintaining high operability during manual operation while accurately supplying hydraulic fluid at a target flow rate without depending on load fluctuations, which affects the transition between manual and automatic control modes.
Innovation Solution
The implementation of a hydraulic drive system with directional control valves connected in parallel, auxiliary flow controllers, and a control validation switch that adjusts flow rates based on load fluctuations and pump saturation, ensuring stable and accurate hydraulic fluid supply for both manual and automatic operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an operator manually operates the work machine, then high operability and responsiveness are achieved, but the hydraulic fluid supply is unstable due to load fluctuations
Solution Approach 1:
A load compensation valve is introduced as an intermediary component between the manual operation system and the hydraulic actuators. This valve automatically compensates for load fluctuations by adjusting the hydraulic fluid supply pressure, thereby stabilizing the actuator operation while preserving the operator's manual control authority and responsiveness.
Solution Approach 2:
The load compensation valve operates autonomously to detect and compensate for load changes in the hydraulic system. It self-adjusts the fluid supply characteristics based on real-time pressure conditions without requiring operator intervention, thereby maintaining stable actuator performance during manual operation.
2Reliability
If a pressure compensating valve is used to stabilize hydraulic fluid supply, then flow rate stability is improved, but the system complexity increases
Solution Approach 1:
The patent employs a load compensation valve that utilizes hydraulic pressure feedback mechanisms to achieve flow rate stabilization. By leveraging hydraulic principles, the system maintains stable fluid supply without requiring complex electronic sensors or control algorithms, thus limiting the increase in system complexity.
3Measurement precision
If area limiting control is implemented, then automatic control precision is improved, but the hydraulic fluid supply becomes dependent on load pressure
Solution Approach 1:
The load compensation valve serves as a mediator that decouples the area limiting control system from load pressure variations. It ensures that the hydraulic fluid supply to actuators remains stable and independent of load changes, thereby enabling precise automatic control without compromising supply reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the speed and accuracy of actuator operation during manual control and improves automatic control accuracy by maintaining consistent flow rates, even under load fluctuations and saturation conditions, thereby ensuring demanded performance in both modes.
Implementation Method 1
regulators exercising horsepower control over the hydraulic pumps in response to load pressures of the plurality of hydraulic actuators
Implementation Method 2
a plurality of directional control valves connected to delivery lines of the hydraulic pumps in parallel and regulating supply flow rates to the plurality of hydraulic actuators from the hydraulic pumps
Implementation Method 3
a plurality of auxiliary flow controllers that are connected to upstream of the plurality of directional control valves and that can limit supply flow rates to the plurality of directional control valves from the hydraulic pumps
Implementation Method 4
operation pressure generation valve devices reducing a delivery pressure of the pilot pump in response to operation instruction amounts from the operation lever devices
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A work machine capable of driving each actuator more speedily and more accurately by ensuring high operability in a case of operator's manual operation, while accurately supplying a hydraulic fluid at a target flow rate to the actuator without depending on a load fluctuation in a case of automatic control over a machine body in response to a command input from a controller is provided. The controller controls a plurality of auxiliary flow controllers in such a manner that supply flow rates to a plurality of directional control valves from hydraulic pumps fluctuate in response to load fluctuations of a plurality of hydraulic actuators in a case in which an instruction on invalidation of an area limiting control function is issued, and controls the plurality of auxiliary flow controllers in such a manner that the supply flow rates to the plurality of directional control valves from the hydraulic pumps do not fluctuate in response to the load fluctuations of the plurality of hydraulic actuators in a case in which an instruction on validation of the area limiting control function is issued.