Hydraulic Valve Timing Calibration via Pump Discharge Pressure
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Solution Overview
Problem
Existing hydraulic systems face challenges in adjusting the movement start and completion timings of flow control and bleed-off valves without the use of pressure sensors, which are difficult to attach and require significant calibration efforts, leading to inefficiencies and increased man-hours.
Innovation Solution
A hydraulic driving system that includes a flow control valve, a bleed-off valve, a discharge pressure sensor, and a controller, which performs calibration by detecting discharge pressure and adjusting command currents to synchronize valve movements with the operation of the operating lever, allowing for precise timing adjustments without pressure sensors at the valve outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are attached to the output side of the flow control valve and bleed-off valve to detect output pressure for calibration, then the movement start timing and movement completion timing of the valves can be adjusted, but the device complexity increases and many man-hours are required for installation and calibration
Solution Approach 1:
The patent uses discharge pressure from the hydraulic pump as an intermediary parameter to indirectly detect valve movement timing. Instead of directly measuring valve output pressure with sensors at each valve, the system monitors the pump's discharge pressure which changes in response to valve movements. This intermediary measurement approach reduces system complexity while maintaining calibration capability.
Solution Approach 2:
The system performs self-calibration by detecting natural pressure changes that occur during valve operation. The calibration process utilizes the inherent pressure fluctuations in the hydraulic system when valves open or close, eliminating the need for external pressure sensors at each valve output. The controller automatically detects these pressure changes and adjusts command currents accordingly.
2Measurement precision
If pressure sensors are attached to the output side of the flow control valve and bleed-off valve to detect output pressure for calibration, then the valve characteristics can be measured, but the ease of manufacture deteriorates due to additional pipes and installation requirements
Solution Approach 1:
The patent employs discharge pressure from the hydraulic pump as a mediator to measure valve characteristics without requiring direct pressure measurement at each valve output. This approach eliminates the need for additional piping and pressure sensor installation at multiple locations, significantly simplifying the manufacturing and calibration process while still enabling accurate valve characteristic measurement.
Solution Approach 2:
The discharge pressure sensor at the pump serves multiple functions: it monitors system pressure, detects valve movement timing, and enables calibration of multiple valves simultaneously. This multi-functional use of a single sensor eliminates the need for separate pressure sensors at each valve, reducing installation complexity while maintaining measurement precision.
3Ease of operation
If command currents are supplied to electromagnetic valves based on operating lever operation, then the hydraulic actuator can be controlled, but the movement start timing and movement completion timing vary due to manufacturing errors
Solution Approach 1:
The patent implements feedback control by monitoring discharge pressure changes that occur when valves open or close. The controller detects these pressure changes and uses them as feedback to adjust the command currents supplied to electromagnetic valves. This feedback mechanism compensates for manufacturing variations in valve response timing, ensuring consistent operation across different valves while maintaining ease of hydraulic actuator control.
Solution Approach 2:
The system dynamically adjusts command current parameters based on detected valve response characteristics. By measuring the actual pressure response timing and modifying the electrical command parameters accordingly, the system compensates for manufacturing tolerances in valve timing without affecting the overall ease of hydraulic control operation.
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 precise adjustment of valve movement timings relative to the operating lever's operation without pressure sensors, reducing calibration time and effort, and ensuring consistent valve performance.
Implementation Method 1
a discharge pressure sensor configured to detect a discharge pressure of the hydraulic pump
Implementation Method 2
a relief valve configured to, when the discharge pressure of the hydraulic pump becomes a relief pressure or more, exhaust to the tank the operating liquid discharged from the hydraulic pump
Implementation Method 3
a hydraulic pump configured to supply the operating liquid to a main passage
Data Source
AI summary
A hydraulic driving system includes a flow control valve device, a bleed-off valve device, a discharge pressure sensor, a relief valve, an operating element, and a controller. The controller executes calibration in which: in a state where the bleed-off valve device blocks between a hydraulic pump and a tank, the controller changes a movement command current supplied to the flow control valve device and makes the discharge pressure sensor detect a discharge pressure; the controller detects at least one of an opening start current that is a current when the flow control valve device starts opening and a closing completion current that is a current when closing of the flow control valve device is completed; and based on the detected at least one current, the controller adjusts a correspondence relation between an operation amount of the operating element and the at least one current.