Variable-Capacity Pump Calibration Without a Flowmeter
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Solution Overview
Problem
Current pump calibration systems for hydraulic pumps are complex and require multiple steps, including pressure measurement and coefficient calculation, making them inefficient for calibrating the relationship between discharge capacity and command signals.
Innovation Solution
A pump calibration system that includes a hydraulic pump, a regulator, an unloader valve, a pressure sensor, and a control device, which stores a reference pressure and adjusts the command signal to match this pressure, allowing for calibration of the pump characteristic without a flowmeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple steps including pressure measurement and coefficient calculation are performed for pump calibration, then calibration accuracy is improved, but calibration complexity and time consumption increase
Solution Approach 1:
The invention extracts and eliminates the flowmeter from the calibration system, replacing it with a pressure-based calibration method. By removing this component and the associated complex coefficient calculation steps, the system achieves simplified calibration while maintaining accuracy through direct pressure measurement and comparison with reference values.
Solution Approach 2:
The invention replaces the mechanical flow measurement system (flowmeter) with a pressure-based measurement and calculation system. Instead of mechanically measuring flow rate, the system measures pressure and calculates the equivalent flow information through pressure-based formulas, thereby simplifying the physical measurement apparatus.
2Measurement precision
If multiple steps including pressure measurement and coefficient calculation are performed for pump calibration, then calibration accuracy is improved, but calibration time increases
Solution Approach 1:
The invention extracts and eliminates the flowmeter from the calibration system, replacing it with a pressure-based calibration method. By removing this component and the associated complex coefficient calculation steps, the system achieves simplified calibration while maintaining accuracy through direct pressure measurement and comparison with reference values.
Solution Approach 2:
The invention stores reference pressure values in advance during the pump's design or initial setup phase. During actual calibration, these pre-stored reference values are directly compared with measured pressures, eliminating the need for complex real-time coefficient calculations and significantly reducing calibration time while maintaining accuracy.
3Measurement precision
If a flowmeter is used for pump calibration, then discharge flow rate measurement is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the flowmeter from the calibration system, replacing it with a pressure-based calibration method. By removing this component and the associated complex coefficient calculation steps, the system achieves simplified calibration while maintaining accuracy through direct pressure measurement and comparison with reference values.
Solution Approach 2:
The invention introduces pressure as an intermediary measurement parameter. Instead of directly measuring flow rate with a flowmeter, the system measures pressure (which is easier to measure accurately) and uses pressure-based calculations to derive flow rate information, thereby achieving the same calibration objective through a different measurement pathway.
4Measurement precision
If a flowmeter is used for pump calibration, then discharge flow rate measurement is improved, but calibration cost increases
Solution Approach 1:
The invention extracts and eliminates the flowmeter from the calibration system, replacing it with a pressure-based calibration method. By removing this component and the associated complex coefficient calculation steps, the system achieves simplified calibration while maintaining accuracy through direct pressure measurement and comparison with reference values.
Solution Approach 2:
The invention replaces the expensive flowmeter with a more economical pressure sensor and calculation-based approach. Pressure sensors are generally less costly than flowmeters, and the computational method used to derive flow information from pressure data is less expensive than the mechanical or electronic components of a flowmeter, thereby reducing overall calibration system cost.
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 easy calibration of the pump characteristic by using the stored reference pressure to derive an actual signal that matches the desired discharge pressure, simplifying the process and eliminating the need for a flowmeter.
Implementation Method 1
a pressure sensor that measures a discharge pressure of the hydraulic pump
Data Source
AI summary
A pump calibration system includes a hydraulic pump of a variable capacity type, a regulator that changes a discharge capacity according to a command signal, an unloader valve having a variable opening degree, a pressure sensor that measures a discharge pressure, and a control device that controls the discharge capacity and calibrates a pump characteristic. The control device stores a first reference pressure detected by the pressure sensor when a first reference signal is output under a measurement condition in which the opening degree of the unloader valve is fixed and the pump is driven to rotate a predetermined amount, and when a calibration condition is satisfied, changes the command signal so that the discharge pressure becomes the first reference pressure, and calibrates the pump characteristic on the basis of a first actual signal that is the command signal with which the discharge pressure is the first reference pressure.