Forklift Load Weight Detection via Hydraulic Pressure Pulse
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Solution Overview
Problem
Existing methods for detecting load weight in industrial trucks with hydraulic lifting devices require a significant amount of time and specific sequences of movement, making the process inefficient and dependent on the lifting direction and reference height.
Innovation Solution
A method that uses a pressure pulse generated by a switchable valve to quickly determine load weight by detecting the mean pressure during a decaying oscillation, eliminating the need for additional sensors and allowing for precise weight calculation without noticeable lifting movement, using existing components like pressure sensors and valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a defined sequence of movements is performed during weighing, then the load weight can be determined with eliminated static friction effects, but the weighing process requires significant time and specific user movements
Solution Approach 1:
The patent applies periodic action by using a pressure pulse that periodically excites the hydraulic lifting device to generate oscillations. The pressure sensor detects the pressure curve during these oscillations, and the load weight is determined from the oscillation characteristics. This periodic excitation eliminates the need for prolonged defined movement sequences while maintaining precision by avoiding static friction effects.
Solution Approach 2:
The patent utilizes mechanical vibration by intentionally inducing oscillations in the hydraulic lifting device through a pressure pulse. The load weight is determined by analyzing the pressure curve during these vibrations. This approach eliminates static friction effects that plague static measurements and provides accurate weight detection without requiring time-consuming defined movement sequences.
2Ease of operation
If the load handling device is moved to a specific reference lifting height, then the weighing procedure can be standardized, but the process becomes dependent on lifting direction and requires additional user actions
Solution Approach 1:
The patent applies self-service by enabling the weighing procedure to be initiated automatically at any lifting height without requiring user intervention to move the load handling device to a specific reference position. The controller automatically generates the pressure pulse and processes the pressure curve to determine load weight, making the system self-sufficient and eliminating dependency on user actions or specific lifting directions.
Solution Approach 2:
The patent utilizes parameter changes by determining load weight from the characteristics of pressure oscillations rather than from pressure values at a specific reference height. This approach changes the measurement parameter from position-dependent pressure to oscillation-based pressure analysis, enabling weighing at any lifting height and eliminating the need to move to standardized reference positions.
3Measurement precision
If pressure is detected during uniform lifting speed sections, then static friction effects are eliminated, but the weighing method requires prolonged movement sequences
Solution Approach 1:
The patent applies periodic action by using a pressure pulse to generate oscillations in the hydraulic lifting device. The load weight is determined from the pressure curve during these oscillations, which naturally eliminate static friction effects. This periodic excitation provides accurate measurements without requiring prolonged uniform lifting sequences.
Solution Approach 2:
The patent utilizes mechanical vibration by inducing oscillations through a pressure pulse and analyzing the pressure curve during these vibrations. This approach eliminates static friction effects while significantly reducing the measurement time compared to prolonged uniform lifting sequences, as the oscillations provide sufficient data for accurate weight determination in a short duration.
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 rapid and precise load weight detection without the need for specific user movements or additional sensors, reducing the time required for weighing and allowing for automatic operation across various lifting heights with minimal calibration.
Implementation Method 1
pressure detection means, in particular a pressure sensor, for detecting the pressure of the hydraulic fluid in the hydraulic lifting device
Implementation Method 2
a switchable valve through which hydraulic fluid can be fed into the lifting device and/or drained from it
Implementation Method 3
hydraulic lifting device for a load handling device that is guided in a height-adjustable manner on a lifting mast
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In a method for determining the load weight of a forklift truck with a hydraulic lifting device for a load-handling attachment that is vertically movable on a lifting mast, with a switchable valve through which hydraulic fluid can be supplied to and/or discharged from the lifting device, and with pressure sensing means, in particular a pressure sensor, for detecting the pressure (p) of the hydraulic fluid in the hydraulic lifting device, in a first step the valve is switched by a control unit for a short pulse period by means of a pressure pulse, a short application of pressure (p) or release of pressure (p), wherein the pulse period is so short that no or no significant lifting movement takes place and after the valve closes the pressure curve (6) shows a decaying oscillation,wherein, during the decaying oscillation in a test period (T), the mean value of the pressure is recorded as load pressure (11) by the pressure sensing means.