Open-Center Hydraulic Pump Calibration for Threshold and Hysteresis Control
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Solution Overview
Problem
Existing hydraulic systems in work machines face challenges in calibrating electro-hydraulic pumps due to manufacturing tolerances, which affect system performance and efficiency.
Innovation Solution
A calibration system and method for electro-hydraulic pumps in open center hydraulic systems, utilizing a controller with program instructions to set thresholds and hysteresis bands by measuring fluid flow pressure, ensuring accurate pump control signals for optimal system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electro-hydraulic pumps are manufactured with standard tolerances, then manufacturing cost and ease of production are improved, but system performance accuracy and control precision deteriorate
Solution Approach 1:
The patent applies preliminary action by implementing a calibration routine before the pump is put into service. The calibration process pre-determines the actual flow characteristics of each pump and stores correction factors in memory, compensating for manufacturing variations before the pump operates in the field. This allows standard manufacturing tolerances to be used while achieving accurate control performance.
Solution Approach 2:
The patent changes operational parameters by adjusting pump control signals based on calibrated data. The system modifies the relationship between control signals and actual pump output by applying correction factors derived from calibration measurements. This parameter adjustment compensates for manufacturing variations and achieves consistent system performance across pumps with different manufacturing tolerances.
2Manufacturing precision
If calibration routines are implemented to account for manufacturing variances, then system performance accuracy is improved, but device complexity and calibration time increase
Solution Approach 1:
The patent applies self-service by enabling the pump system to perform its own calibration automatically. The calibration routine uses the pump's existing sensors and control mechanisms to measure its own performance characteristics and store correction data in its memory. This eliminates the need for external calibration equipment or complex manual procedures, reducing overall system complexity while maintaining accuracy.
Solution Approach 2:
The patent implements feedback by using measured pump performance data to adjust control signals. The calibration process establishes a relationship between control inputs and actual pump output, creating a feedback loop that compensates for manufacturing variations. This automated feedback mechanism simplifies the calibration system by using the pump's own operational data rather than requiring complex external measurement systems.
3Manufacturing precision
If calibration routines are implemented to account for manufacturing variances, then system performance accuracy is improved, but calibration time and productivity decrease
Solution Approach 1:
The pump system performs calibration automatically using its own sensors, actuators, and memory without requiring external calibration equipment or manual intervention. This self-calibration capability significantly reduces calibration time and eliminates the need for specialized calibration tools, making the process efficient and suitable for field implementation.
Solution Approach 2:
The calibration is performed as a preliminary setup step that occurs once during installation or maintenance, rather than requiring continuous calibration. The calibration data is stored in memory and used repeatedly during normal operation, making the time investment one-time rather than recurring, thus improving overall productivity.
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 calibration system ensures precise control of fluid flow and pressure, enhancing the accuracy and efficiency of hydraulic actuation in work machines by identifying critical calibration points and hysteresis bands.
Implementation Method 1
A pressure transducer is positioned for measuring a flow pressure in the hydraulic circuit between the pump and the implement control valve
Implementation Method 2
an electro-hydraulically controlled pump for controlling an outlet flow of the fluid through the hydraulic circuit in response to a pump control signal
Data Source
AI summary
A work machine and method for a work machine with an open center hydraulic system for controlling actuation of an implement includes an implement control valve, an electro-hydraulically controlled pump, a hydraulic circuit coupled to the implement actuator, and a pressure transducer positioned for measuring a pressure in the hydraulic circuit between the pump and the implement control valve. A calibration system for calibrating the pump includes a controller having a non-transitory computer readable medium having a program instruction for causing a processor to calibrate a first pump threshold for the pump in a pump-flow curve wherein the first pump threshold including a minimum pump control signal to actuate the pump; determine a hysteresis band in the pump-flow curve; and calibrate a second pump threshold for the pump in the pump-flow curve wherein the second pump threshold including a maximum pump control signal to actuate the pump below a relief setpoint.