Forklift Lifting Height Control via Magnetic Sensor Detection
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Solution Overview
Problem
Fork-lift trucks face challenges in maintaining a constant maximum lifting height regardless of support arm position and varying lifting height based on load, especially when protective side guards are in their protective position or when support arms are lowered.
Innovation Solution
Incorporating a magnetic or ferromagnetic elongated element on the lifting device and a sensor on the mast structure to detect its presence or absence, allowing the fork-lift truck to control the lifting device's movement, stopping or ramping down when necessary to maintain a constant maximum lifting height independent of support arm position and load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lifting device is limited to a maximum lifting height when protective side guards are in protective position, then operator safety is improved, but the maximum lifting height is reduced when support arms are lowered
Solution Approach 1:
The patent applies dynamics by making the maximum lifting height limit adaptive rather than fixed. The system dynamically adjusts the lifting height limit based on the position of the support arms (detected via sensor) and the type of lifting device (selectable via interface). When support arms are in upright position, a first maximum lifting height is applied; when lowered, a second maximum lifting height is applied. This dynamic adjustment resolves the contradiction by allowing the system to maintain safety while adapting to different operational configurations.
Solution Approach 2:
The patent changes the parameter of maximum lifting height based on detected conditions. The control system modifies the lifting height parameter according to support arm position (detected by sensor) and lifting device type (selected via interface). This parameter change allows the system to provide different lifting height limits for different operational modes, resolving the contradiction between safety requirements and operational flexibility.
2Manufacturing precision
If the lifting device stops immediately at maximum lifting height, then lifting precision is improved, but hydraulic system stability deteriorates due to sudden stopping
Solution Approach 1:
The patent applies beforehand cushioning by implementing a deceleration phase before the lifting device reaches the maximum lifting height. The control system is configured to decelerate the lifting device as it approaches the limit position, preventing sudden stopping. This cushioning effect absorbs the hydraulic momentum and prevents instability while still achieving precise positioning at the maximum lifting height, thus resolving the contradiction between lifting precision and hydraulic system stability.
3Device complexity
If the lifting device continues moving after reaching maximum lifting height due to hydraulic pump momentum, then hydraulic system simplicity is maintained, but lifting height control precision deteriorates
Solution Approach 1:
The patent implements feedback by using a sensor to detect the position of the lifting device and providing this information to the control system. The control system continuously monitors the lifting height and adjusts the hydraulic pump operation accordingly, stopping the pump before the lifting device reaches the maximum height to account for momentum. This feedback loop maintains hydraulic system simplicity while achieving precise lifting height control, resolving the contradiction between system simplicity and control precision.
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
Enables the fork-lift truck to consistently reach the maximum lifting height even with lowered support arms and prevents lifting height variation due to load, ensuring consistent operation and compliance with safety standards.
Implementation Method 1
an elongated element (6) comprising a magnetic or ferromagnetic material arranged on the lifting device (4). A sensor (7) arranged on the mast structure (2) is configured to sense a presence/absence of the elongated element (6)
Data Source
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AI summary
The present disclosure relates to a fork-lift truck with support arms and a mast structure, arranged to provide a constant maximum lifting height independent of the position of the support arms, wherein the fork-lift truck further comprises, a lifting device, carried by the mast structure and movable along the mast structure. The fork-lift truck further comprises an elongated element comprising a magnetic or ferromagnetic material arranged on the lifting device. A sensor arranged on the mast structure is configured to sense a presence/absence of the elongated element. The fork-lift truck is operative to stop an upward movement of the lifting device when the senor senses the presence of the elongated element in a case where the support arms are in an upright position, to provide the constant maximum lifting height. The fork-lift truck is further operative to ramp down the speed of the upward movement of the lifting device in a case where the support arms are in a lowered position and stop the movement of the lifting device when the lifting device has moved upwards a predetermined distance wherein the sensor sense the absence of the elongated element, to provide the constant maximum lifting height. The present disclosure further related to a method of operating a fork-lift truck and a method of modifying a fork-lift truck, such that the fork-lift truck is able to provide a constant maximum lifting height independent of the position of the support arms.