Hydraulic Excavator Flow Control for Manual-Auto Mode Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulic excavators face challenges in accurately controlling actuator flows during automatic operation due to load variations, leading to instability and discomfort for operators, which complicates the transition between manual and automatic control modes.
Innovation Solution
A hydraulic drive system with auxiliary flow rate control devices that limit and adjust flow rates based on pressure variations, allowing for precise control of directional control valves, ensuring accurate flow rates regardless of load changes and enhancing operability during manual operation while improving automatic control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure-compensating valves are arranged in series with directional control valves to supply flows at accurate rates without load variations, then automatic control precision is improved, but operator comfort deteriorates due to loss of operational changes
Solution Approach 1:
The system dynamically switches between two operational modes: automatic control mode where pressure-compensating valves maintain precise flow rates regardless of load variations, and manual operation mode where the same valves are deactivated to allow operators to feel load changes through the control levers. This dynamic reconfiguration resolves the contradiction by providing precise automatic control when needed while preserving operator feedback during manual operation.
Solution Approach 2:
The system changes the operational parameters of the pressure-compensating valves based on the control mode. In automatic control mode, the valves are activated with specific pressure compensation settings to ensure accurate flow rates. In manual operation mode, the valves are deactivated or their compensation parameters are adjusted to allow natural feedback of load variations to the operator, thus resolving the contradiction through parameter adaptation.
2Manufacturing precision
If flow rates are supplied accurately at target rates without load variations during automatic control, then actuator control precision is improved, but operability deteriorates due to loss of actuator operation changes
Solution Approach 1:
The system dynamically adjusts the engagement state of pressure-compensating valves based on whether automatic control or manual operation is active. During automatic control, the valves engage to provide precise flow rate control unaffected by load variations. During manual operation, the valves disengage to allow operators to perceive actuator load changes, thus resolving the contradiction between precision and operability through dynamic mode-dependent behavior.
Solution Approach 2:
The system extracts or removes the pressure-compensation function from the hydraulic control path during manual operation, allowing operators to directly feel load variations. During automatic control, the pressure-compensation function is reinserted to ensure precise flow rates. This selective extraction and reinsertion of the compensation mechanism resolves the contradiction by applying it only when needed for precision while preserving natural feedback for operability.
3Adaptability or versatility
If switching is performed between manual operation function and automatic control function, then versatility is improved, but system complexity increases
Solution Approach 1:
The pressure-compensating valves serve dual functions: during automatic control, they provide precise flow rate compensation; during manual operation, they are deactivated to allow natural operator feedback. This multi-functionality of the same hardware component reduces the need for separate systems for each mode, thus resolving the contradiction between versatility and complexity by making existing components perform multiple roles.
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
Enables faster and more accurate actuator control in hydraulic excavators by maintaining consistent flow rates, improving operator comfort and machine performance across both manual and automatic operation modes.
Implementation Method 1
limit the flow rate of a hydraulic fluid supplied from a hydraulic pump to a plurality of directional control valves in accordance with pressure variations at a plurality of hydraulic actuators
Data Source
AI summary
To provide a work machine that makes it possible to drive actuators faster and more accurately by supplying flows to the actuators accurately at target rates without depending on load variations in a case where the machine body is controlled automatically by command inputs of a controller, while high operability is ensured for manual operation by an operator. In a case where a machine control function is cancelled via a machine control switch, a controller cancels limitation of the flow rate of a hydraulic fluid supplied to a plurality of directional control valves, the limitation being performed by the auxiliary flow rate control devices, and in a case where the machine control function is selected via the machine control switch, the controller causes the auxiliary flow rate control devices to limit the flow rate of the hydraulic fluid supplied to the plurality of directional control valves.