Reach Carriage Speed Control via Closed-Loop Feedback

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Solution Overview

Problem

Industrial trucks with reach carriages often fail to maintain the specified speed due to external influences like manufacturing tolerances, frictional forces, and material wear, leading to inaccurate speed control and unwanted vibrations, which can result in unsafe high speeds or slowed workflows.

Innovation Solution

An industrial truck equipped with sensors to measure actual speed and deformation, and a control unit that adjusts the movement speed of the reach carriage to match the specified target speed, compensating for external factors and actively damping vibrations to ensure precise speed control and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a hydraulic drive system is used to control the speed of the lifting frame's sliding carriage, then the system can achieve basic speed control through valve characteristic curves, but the actual speed deviates from the set speed due to external influences such as manufacturing tolerances, fluctuating frictional forces, material wear, and other static or dynamic forces

Engineering Contradiction:
Improvespeed control accuracyVSAvoidspeed consistency
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent implements a closed-loop feedback control system where a sensor measures the actual speed of the sliding carriage and feeds this information back to the control unit. The control unit compares the measured speed with the set speed and automatically adjusts the manipulated variable to the hydraulic valve to eliminate speed deviations, thereby maintaining consistent actual speed despite external disturbances.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the purely mechanical/hydraulic speed control system with an electronically controlled system. The control unit processes speed feedback signals and dynamically adjusts the hydraulic valve actuation, substituting manual or open-loop mechanical control with automated electronic regulation to achieve more precise and reliable speed control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the push carriage is moved quickly to maintain high workflow speed, then productivity increases, but unwanted oscillation of the push mast and load occurs

Engineering Contradiction:
Improveworkflow speedVSAvoidmast stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies dynamic control by continuously adjusting the speed profile of the push carriage based on real-time feedback. The control system modulates the actuation forces to maintain optimal dynamic behavior, allowing high speeds while preventing mast oscillation through active damping and adaptive speed regulation rather than relying on fixed mechanical constraints.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3336049B1Industrial truck with a control unit for regulating the movement of a load and corresponding method
Publication Date: 2020.07.22 JUNGHEINRICH AG
  • EP3336049B1 patent drawingFigure 1
  • EP3336049B1 patent drawingFigure 2
  • EP3336049B1 patent drawingFigure 3

AI summary

Industrial truck comprising a lifting frame with a load part for carrying a load, a push carriage acting on the lifting frame for moving the lifting frame forward and backward, at least one sensor designed to measure the actual speed of the push carriage, and a control unit designed to specify a target speed for the push carriage, to determine a control deviation of the actual speed measured by the at least one sensor from the target speed, and to control the movement speed of the push carriage based on the determined speed deviation.