Hydraulic Actuator Calibration via Meter-In Pressure Control
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Solution Overview
Problem
Existing construction machine control systems face challenges in accurately deriving the operation characteristics of hydraulic actuators, particularly in high-velocity areas, due to the influence of inertia and viscous resistance, which limits precision and requires extensive calibration.
Innovation Solution
A construction machine with a controller that adjusts differential pressure across the meter-in valve during calibration, allowing indirect mapping of spool position and actuator velocity without high-speed actuator movement, thereby mitigating the effects of inertia and viscous resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actuators are moved at high velocities to acquire measurement data in a high-velocity area, then the measurement data in high-velocity area can be acquired, but the influence of inertia and viscous resistance becomes dominant, making it difficult to accurately map velocities at the steady state relative to the spool positions
Solution Approach 1:
The patent changes the parameter of differential pressure across the meter-in valve during calibration. By reducing the differential pressure when the spool position changes to increase the opening area, the system suppresses the flow rate increase and consequently reduces the actuator velocity, keeping it in a low-velocity range where inertia and viscous resistance effects are minimal.
Solution Approach 2:
The patent introduces differential pressure as an intermediary control variable between the spool position and the actuator velocity. Instead of directly mapping spool position to velocity at high speeds, the system uses differential pressure adjustment as an intermediate step to indirectly control and measure the velocity relationship, enabling accurate characteristic derivation without high-velocity operation.
2Measurement precision
If the spool is accelerated for a long time to gradually accelerate the actuator and reduce inertia effects, then the influence of inertia can be reduced, but the limit of the movable range of the actuator is exceeded
Solution Approach 1:
The patent changes the differential pressure parameter dynamically during calibration based on the spool position change direction. When the spool position increases the opening area, the differential pressure is reduced to suppress flow rate and velocity increases. This allows the actuator to operate within its movable range while still enabling accurate derivation of high-velocity area characteristics through controlled low-velocity measurement.
3Productivity
If direct mapping of spool positions and actuator velocities is performed, then the calibration process is simple, but it requires extensive calibration operations and cannot acquire data in high-velocity area without high-speed actuator movement
Solution Approach 1:
The patent uses differential pressure as an intermediary variable to enable indirect mapping between spool position and actuator velocity. This approach maintains calibration simplicity while improving precision, as the differential pressure adjustment allows the system to derive high-velocity area characteristics without requiring actual high-speed actuator operation or extensive calibration iterations.
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 approach enables precise derivation of operation characteristics in high-velocity areas with reduced calibration operations, improving precision and efficiency.
Implementation Method 1
a pressure sensor that senses a differential pressure across the meter-in valve
Implementation Method 2
a velocity sensor for sensing an operation velocity of the hydraulic actuator
Implementation Method 3
a hydraulic pump that is driven by the prime mover, and delivers, as a hydraulic fluid, the hydraulic operating fluid sucked in from the tank
Implementation Method 4
a meter-in valve that adjusts a flow rate of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator
Data Source
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AI summary
A construction machine that precisely enables derivation of the operation characteristics of hydraulic actuators in a high-velocity area with less calibration operation is provided. A controller (10) has a calibration mode in which the controller (10) derives operation characteristics (α(xs)) representing a relation among a spool position (xs) of a meter-in valve (8a1), an operation velocity (Va) of a hydraulic actuator (4a), and a differential pressure (ΔP) across the meter-in valve (8a1), and is configured to, in a case where the spool position (xs) of the meter-in valve (8a1) has changed in a direction to increase the opening area of the meter-in valve (8a1) in the calibration mode, output a command signal to increase the opening area of a bleed-off valve (8b1) to a bleed-off solenoid proportional pressure-reducing valve (8b2) as a command signal to reduce the differential pressure (ΔP).