Active Pump Displacement Control for Hydrostatic Pressure Balancing

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Solution Overview

Problem

Hydrostatic propulsion drive systems in agricultural vehicles often require manual recalibration of tandem hydrostatic pumps to maintain equal output pressures, which is impractical due to the need for specialized tools and time-consuming disassembly, leading to uneven wear and premature failure of pumps.

Innovation Solution

An active pump displacement control system that uses pressure sensors and coils to automatically adjust and equalize the output pressures of hydrostatic pumps in real-time, ensuring both pumps share the propulsion load equally, thereby extending their lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual calibration of hydrostatic pumps is performed to equalize output pressures, then pump pressure balance is improved, but maintenance time and complexity increase due to disassembly requirements

Engineering Contradiction:

Improvepump pressure balanceVSAvoidmaintenance time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical calibration with an electronic control system that uses pressure sensors to detect pump output pressures and electronically controlled displacement mechanisms to automatically adjust and equalize the pressures, eliminating the need for manual disassembly and calibration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system enables self-calibration through automatic pressure detection and adjustment mechanisms, where the hydrostatic drive system continuously monitors and self-corrects pressure imbalances without requiring external intervention or disassembly of components

Inventive Principle:

Principle #25Self-service

2Reliability

If manual recalibration is performed periodically to maintain equal pump output pressures, then pump lifespan is improved through equal load sharing, but operational downtime increases

Engineering Contradiction:

Improvepump lifespanVSAvoidoperational availability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system provides continuous pressure monitoring and adjustment during pump operation, ensuring equal load distribution is maintained at all times rather than relying on periodic manual recalibration, thus preventing uneven wear while maintaining operational continuity

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

Pressure sensors continuously monitor the output pressures of both pumps and provide feedback to the control system, which automatically adjusts pump displacements to maintain equal pressures, creating a closed-loop system that ensures consistent load sharing and extends pump lifespan without operational interruption

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If specialized tools and disassembly are used for pump calibration, then pressure equalization accuracy is improved, but ease of operation deteriorates

Engineering Contradiction:

Improvepressure equalization accuracyVSAvoidcalibration ease

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent replaces complex mechanical calibration tools and procedures with an electronic control system that uses sensors and electronic actuators to achieve precise pressure equalization, dramatically simplifying the calibration process while maintaining or improving accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs automatic pressure equalization without requiring operator intervention or specialized tools, making the calibration process as simple as initiating the self-calibration sequence through the control interface, thereby greatly improving ease of operation while maintaining precision

Inventive Principle:

Principle #25Self-service

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 allows for continuous, real-time adjustment of hydrostatic pump pressures, reducing the need for frequent manual recalibration and extending the life of the pumps by ensuring equal load sharing, making maintenance more efficient and reducing the frequency of service tasks.

Implementation Method 1

a pressure sensor(s) for determining output pressure of hydrostatic pumps

Methodology Applied

Scientific EffectPressure sensing:

Implementation Method 2

use the output pressure values within a feedback loop to provide coil input values of coils that control displacement of the hydrostatic pumps

Methodology Applied

Scientific EffectElectromagnetic actuation: Electromagnet

Data Source

PatentUS10801617B2Propel system with active pump displacement control for balancing propel pump pressures in agricultural vehicles

Publication Date: 2020.10.13 BLUE LEAF I P INC

AI summary

A propel system of an agricultural vehicle has an active pump displacement control system for equalizing or balancing pressure output of hydrostatic pumps of a tandem pump propel arrangement. The active pump displacement control system may include a pressure sensor(s) for determining output pressure of hydrostatic pumps and use the output pressure values within a feedback loop to provide coil input values of coils that control displacement of the hydrostatic pumps so that the pressure outputted by the hydrostatic pumps can be equalized in real-time while on the go during use of the agricultural vehicle.