Forklift Control Device Vibration Offset via Phase Inversion
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Solution Overview
Problem
The existing forklifts experience delays in fork movement during raising/lowering operations and insufficient reduction of load vibrations due to non-linear relationships between energizing current and hydraulic oil supply, leading to inefficient vibration offsetting.
Innovation Solution
A forklift with a control device that calculates and outputs speed and current command values to generate specific vibrations phases and amplitudes, using a memory-based system to adjust the energizing current and hydraulic oil supply non-linearly, ensuring 180° phase difference and matched amplitudes for effective vibration offsetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the current command value is gradually increased in two steps to generate offsetting vibrations, then load vibration is reduced, but fork movement delay increases and operability deteriorates
Solution Approach 1:
The control device generates periodic vibrations in the load by periodically adjusting the energizing current to the control valve. A first vibration is generated when lowering starts, and a second vibration with opposite phase is generated after a predetermined time period, creating an offsetting effect that reduces overall load vibration while maintaining responsive fork movement
Solution Approach 2:
The control device changes the parameters of the energizing current (amplitude, duration, timing) to generate vibrations with specific characteristics. By precisely controlling the current command values and their timing, the system generates vibrations that are 180° out of phase to offset each other, resolving the contradiction between vibration reduction and movement responsiveness
2Device complexity
If the energizing current is adjusted linearly, then control simplicity is maintained, but vibration offsetting precision is insufficient due to non-linear hydraulic response
Solution Approach 1:
The control device changes the parameters of the energizing current (amplitude, duration, timing) to generate vibrations with specific characteristics. By precisely controlling the current command values and their timing, the system generates vibrations that are 180° out of phase to offset each other, resolving the contradiction between vibration reduction and movement responsiveness
Solution Approach 2:
The control device uses feedback from vibration sensors to detect the actual vibration state of the load and adjusts the energizing current accordingly. This closed-loop control ensures precise vibration offsetting by continuously monitoring and correcting the vibration amplitude and phase, achieving high precision without overly complicating the control system
3Object-affected harmful factors
If the second vibration amplitude matches the first vibration amplitude, then vibration cancellation is maximized, but control complexity increases due to non-linear current-supply relationship
Solution Approach 1:
The control device changes the parameters of the energizing current (amplitude, duration, timing) to generate vibrations with specific characteristics. By precisely controlling the current command values and their timing, the system generates vibrations that are 180° out of phase to offset each other, resolving the contradiction between vibration reduction and movement responsiveness
Solution Approach 2:
The control device dynamically adjusts the energizing current based on the detected vibration state rather than using fixed predetermined values. This dynamic control allows the system to adapt to varying load conditions and maintain optimal vibration cancellation while managing control complexity through real-time adjustments
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
This solution reduces delays in fork movement and effectively reduces load vibrations by ensuring precise control over the energizing current and hydraulic oil supply, enhancing operability and vibration mitigation.
Implementation Method 1
a control valve for controlling the amount of hydraulic oil supplied/discharged, in accordance with an energizing current
Implementation Method 2
a pair of right and left hydraulic cylinders for performing an operation of raising/lowering the forks along the masts at an ascending/descending speed in accordance with an amount of hydraulic oil supplied/discharged
Data Source
Figure 1
Figure 2
Figure 3(A)~3(D)
AI summary
An industrial vehicle includes a holding portion for holding a load, a raising/lowering portion 5 for performing an operation of raising/lowering the holding portion, a control valve 8 for controlling the amount of hydraulic oil suppled to or discharged from the raising/lowering portion 5, and a control device 10 for supplying an energizing current to the control valve 8; the control device 10 includes a speed calculation unit 10A for calculating first and second speed command values for an ascending/descending speed, a current calculation unit 10B for calculating first and second current command values for the energizing current, and a current supply portion 10C for supplying first and second energizing currents to the control valve 8, thereby offsetting a first vibration generated in the load upon start of supplying the first energizing current, by a second vibration generated in the load upon start of supplying the second energizing current.