Power Management Control for Hydrostatic Drive Systems

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Solution Overview

Problem

Power machines experience engine stalling due to excessive load on the engine, which exceeds its power limits, particularly in hydrostatic drive and hydraulic systems, necessitating a solution to manage power usage effectively.

Innovation Solution

A power management control system that utilizes feedback from an RPM sensor to adjust hydrostatic parameters, allowing users to activate or deactivate power management control through a user interface, which includes a power management component that determines control inputs to manage engine power usage by adjusting pump stroke or displacement based on engine load and operator input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the engine power is increased to meet excessive load demands, then the power limit is improved, but the fuel consumption and engine size increase

Engineering Contradiction:
Improveengine powerVSAvoidfuel consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic adjustment of hydrostatic drive parameters (pump displacement, motor displacement) based on real-time operating conditions. The control system continuously monitors engine RPM, hydraulic system demands, and adjusts pump and motor displacements dynamically to match actual power needs, preventing engine stalling while avoiding excessive fuel consumption from oversized power delivery

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters of the hydrostatic drive components - specifically pump displacement and motor displacement - to optimize power transmission. By adjusting these parameters based on engine load and RPM feedback, the system adapts power delivery to match actual work demands, resolving the contradiction between maintaining sufficient power and reducing fuel consumption

Inventive Principle:
Principle #35Parameter changes

2Power

If the pump displacement is increased to meet hydraulic demand, then the hydraulic power output is improved, but the engine load increases causing stalling

Engineering Contradiction:
Improvehydraulic power outputVSAvoidengine stalling
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The control system uses feedback from engine RPM sensors to monitor actual engine operating conditions. When engine RPM drops indicating approaching stall conditions, the system automatically adjusts pump and motor displacements to reduce hydraulic power demand, preventing engine stalling while maintaining adequate hydraulic output for work functions

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts pump displacement and motor displacement based on real-time engine load conditions. By making these components variable rather than fixed, the system can increase hydraulic power output when needed while reducing displacement when engine load becomes excessive, preventing stalling

Inventive Principle:
Principle #15Dynamics

3Use of energy by moving object

If the engine speed is reduced to improve fuel consumption, then the energy efficiency is improved, but the available power decreases

Engineering Contradiction:
Improvefuel consumptionVSAvoidavailable power
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The system changes the displacement parameters of the hydrostatic pump and motor to decouple engine speed from hydraulic power output. By increasing pump or motor displacement, the system can maintain adequate hydraulic power delivery even at reduced engine speeds, allowing fuel consumption to decrease without sacrificing available power for work functions

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2155972B1Power machine or vehicle with power management
Publication Date: 2019.12.25 CLARK EQUIPMENT CO
  • EP2155972B1 patent drawingFigure 1
  • EP2155972B1 patent drawingFigure 2
  • EP2155972B1 patent drawingFigure 3

AI summary

Power management control for a power machine or vehicle is disclosed. In illustrated embodiments, a user interface (130) of the power machine or vehicle includes a power management selection (232) for activating and deactivating power management control. In illustrated embodiments, power management control is implemented through a power management control component (222) based upon feedback from an RPM sensor (224). As disclosed in illustrative embodiments, the power management control component (222) utilizes control methods and characteristics stored in system memory to determine control input to adjust hydrostatic parameters for power management.