Variable Hydraulic Pump Flow Calibration Using Pressure Difference
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Solution Overview
Problem
Existing hydraulic pump systems experience variations in actual pump flow rates compared to command discharge flow rates, leading to discrepancies between the desired and actual fluid discharge, particularly in variable capacity pumps.
Innovation Solution
A pump system that includes a hydraulic pump, a regulator, an opening degree control valve, pressure sensors, and a control device to create a correction table based on pressure differences and opening degrees, allowing for precise adjustment of discharge flow rates to minimize discrepancies between command and actual flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pump characteristics are calibrated on the basis of specified pump flow rates, then the pump control table can be established, but a difference occurs between the actual pump flow rate and the command discharge flow rate when the pump flow rate varies from pump to pump
Solution Approach 1:
The invention changes the calibration parameter from specified pump flow rates to pump pressure measurements. By measuring pump pressure at multiple current command values and calculating actual discharge flow rates based on pressure differences across a control valve, the system establishes accurate pump characteristics that account for individual pump variations, thereby resolving the discrepancy between command and actual discharge flow rates.
2Adaptability or versatility
If the pump flow rate is allowed to vary from pump to pump, then each pump can operate independently, but the difference between command discharge flow rate and actual pump flow rate increases
Solution Approach 1:
The invention implements a feedback mechanism where pump pressure is measured and used to calculate the actual discharge flow rate. This actual flow rate information is then used to create an accurate pump control table that compensates for individual pump variations. The feedback loop ensures that each pump's unique characteristics are captured and compensated for, maintaining discharge flow rate consistency despite pump-to-pump variability.
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
The system effectively minimizes the difference between command discharge flow rates and actual pump flow rates by using pressure sensors and a control device to calculate and correct fluid discharge, ensuring accurate fluid delivery.
Implementation Method 1
a first pressure sensor that measures upstream pressure that is hydraulic pressure of a working fluid flowing from the hydraulic pump to the opening degree control valve; a second pressure sensor that measures downstream pressure that is hydraulic pressure of the working fluid flowing from the opening degree control valve
Data Source
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AI summary
This pump system includes: a hydraulic pump of the variable capacity type; a regulator; an opening degree control valve; a first pressure sensor that measures the upstream pressure of the opening degree control valve; a second pressure sensor that measures the downstream pressure of the opening degree control valve; and a control device that controls the discharge capacity of the hydraulic pump according to pump characteristics. By changing a command signal to be output to the regulator, under a measurement condition in which the opening degree of the opening degree control valve is fixed at a predetermined opening degree, the control device causes the first pressure sensor and the second pressure sensor to detect the upstream pressure and the downstream pressure, respectively, with a plurality of command signals different from each other, calculates, for each command signal, an actual discharge flow rate of the working fluid discharged from the hydraulic pump, on the basis of the opening degree of the opening degree control valve and the upstream-downstream pressure difference of the opening degree control valve that is calculated on the basis of the upstream pressure and the downstream pressure, and creates a correction table on the basis of the command discharge flow rate and the actual discharge flow rate with respect to each command signal.