Hydraulic Pump Control Calibration for Consistent Load Sensitivity
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Solution Overview
Problem
Existing methods for calibrating hydraulic pumps in hydrostatic drive systems require additional components or complex control systems to compensate for variations in pump sensitivity, leading to increased costs.
Innovation Solution
A software-based calibration method that adjusts the pump sensitivity by measuring and correcting control pressure values using interpolation functions based on the pump's operating conditions, eliminating the need for physical adjustments or additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adjustment of the pump by means of a torque screw is used to ensure the same load sensitivity, then the driving performance consistency is improved, but the adjustment procedure complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical adjustment system (torque screw) with an electronic control system that uses a calibration method based on measuring actual pump sensitivity and adjusting control parameters accordingly. This substitution eliminates the need for physical adjustment procedures while achieving the same load sensitivity consistency.
Solution Approach 2:
The patent changes the approach from physically adjusting mechanical parameters (torque screw adjustment) to electronically modifying control parameters (control pressure values) based on measured pump characteristics. This allows for automatic calibration without manual intervention.
2Reliability
If closed-loop control circuits are used to adjust pressure and swing angle, then the tolerance compensation is improved, but the device complexity and component cost increase
Solution Approach 1:
The patent extracts the essential calibration function from the complex closed-loop control system. Instead of using full closed-loop control with additional sensors and components, the patent implements a simplified calibration method that determines pump sensitivity characteristics and compensates for tolerances through software-based parameter adjustment.
Solution Approach 2:
The patent creates a digital model of the pump's actual sensitivity characteristics through measurement and calibration, then uses this copied information to adjust control parameters. This virtual calibration replaces the need for physical tolerance compensation mechanisms.
3Measurement precision
If additional sensors are added to the system, then the measurement precision is improved, but the cost and device complexity increase
Solution Approach 1:
The patent enables the pump system to self-calibrate by using existing system components to measure and determine pump sensitivity characteristics. The system uses available sensors and measurements to automatically determine calibration parameters without requiring additional measurement devices or external intervention.
Data Source
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Figure 3a~3b
AI summary
The present invention relates to a method for calibrating a hydraulic pump control system (12) for a hydrostatic drive system, wherein said hydrostatic drive system comprises said hydraulic pump (12), the rotation of which is provided by a drive motor, and at least one hydraulic motor connected in a closed circuit to said hydraulic pump (12), wherein said hydraulic pump (12) has an adjusting unit (4) for adjusting the displacement of said hydraulic pump, wherein said displacement is adjustable by adjusting an angle of inclination (αpmp) of an inclined element (2), wherein said adjusting unit (4) has an adjusting cylinder (6) with a first adjusting pressure chamber (81) in which, by means of a first valve (181) it is possible to set a first control pressure (pst1) that depends on a first current intensity (I1) of the first valve (181) and that is configured to affect the inclination (αpmp) of said inclined element (2), wherein said control unit (4) is configured so that an increase in the delivery pressure of the hydraulic pump (2) tends to cause a reduction in the displacement of the hydraulic pump (12), said control system includes a function for calculating said first current intensity (I1) and/or said first control pressure as a function of a rotational speed of said drive motor or a quantity dependent thereon and on the basis of said angle of inclination (αpmp); said method being characterized by the fact that said function is calibrated and by the fact that said calibration includes said steps: a. Define at least a first state of said hydrostatic drive system at which said calibration is to be performed, wherein said first state comprises one or more operating conditions, wherein each operating condition comprises a discharge pressure value of said hydraulic pump (12); b. Measure the value of said first current intensity (I1) and/or said first control pressure required to arrive at each operating condition; c. Compare the value of said first current intensity (I1) and/or said first control pressure with a reference value of each operating condition; d. Correct said function according to the comparison made at said step c.