Pallet Truck Fork Carriage Height Calculation
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Solution Overview
Problem
Existing pallet trucks rely on mechanical sensors and switches to determine the height of the vertically moveable fork carriage, which are prone to failure and maintenance issues, leading to potential damage from contact with the floor and increased operational costs.
Innovation Solution
A pallet truck system that calculates the carriage height using a microprocessor and timer, adjusting the height based on the duration of lift and lower commands, eliminating the need for mechanical devices and allowing real-time speed adjustments to prevent floor contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical sensors and switches are used to determine carriage height, then height detection can be achieved, but the system becomes unreliable and requires frequent maintenance
Solution Approach 1:
The patent replaces mechanical sensors and switches with an electronic control system that calculates carriage height by integrating vertical movement signals from the actuator. The controller accumulates vertical displacement information to determine carriage position, eliminating the need for mechanical height-detecting components and their associated wiring, thereby improving reliability while reducing mechanical complexity.
2Measurement precision
If multiple height sensors are used to ensure accurate height detection, then detection reliability improves, but manufacturing and maintenance costs increase
Solution Approach 1:
The patent creates a virtual copy of the physical height measurement system by calculating carriage height through integration of vertical movement commands rather than using multiple physical sensors. This computational approach provides the necessary measurement precision without the increased manufacturing and maintenance costs associated with redundant mechanical sensors.
3Productivity
If the pallet truck travels at high speed when carriage height is low, then productivity increases, but the risk of floor contact and damage increases
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors calculated carriage height and compares it to a predetermined minimum height threshold. When the carriage is detected to be below the minimum height, the controller automatically limits the maximum travel speed of the pallet truck, preventing floor contact damage while allowing high-speed operation when the carriage is at safe heights.
Data Source
AI summary
A pallet truck including a controller that calculates the height of the fork carriage without the use of mechanical devices such as switches or sensors. A calculated carriage height is derived by adding the amount of time that a carriage is commanded to be raised and offsetting that by the amount of time that the carriage lower button is depressed. The calculated carriage height is essentially an accumulated lift time where the time that the carriage is lifting is a positive value and the time that the carriage is lowering is a negative value. When these values are combined, the result is the present calculated carriage height. The controller further monitors the calculated carriage height such that if the carriage is too close to the ground, the maximum speed of the pallet truck is limited to prevent damage to the forks or ground due to striking or scraping between them.