Lifter Weight Determination via Bi-directional Flow Control
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Solution Overview
Problem
Existing weight determination methods for lifting devices require complex and expensive hydraulic valve systems to maintain constant speed, leading to inaccurate measurements due to acceleration spikes and harmonic oscillations, and are not cost-effective for widespread industry use.
Innovation Solution
A bi-directional flow controller is used to maintain a substantially constant flow through the hydraulic system during both upward and downward displacements, allowing for accurate weight determination without the need for high-performance control systems, and incorporating a processor to register and balance acceleration-dependent parameters for precise calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex hydraulic valve system is used to maintain constant speed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex constant speed valve system from the hydraulic circuit. Instead of maintaining constant speed through complex valves, the invention measures pressure and position signals during actual lifting/lowering operations and uses computational methods to compensate for velocity variations and friction effects, thereby achieving accurate weight determination without the expensive valve system.
Solution Approach 2:
The patent replaces the mechanical hydraulic valve system with an electronic/computational solution. Pressure sensors, position sensors, and a microprocessor work together to calculate weight by compensating for friction and velocity effects through signal processing and mathematical algorithms, substituting mechanical complexity with electronic intelligence.
2Measurement precision
If the hydraulic actuator is operated at constant speed, then measurement precision is improved, but acceleration spikes and harmonic oscillations are minimized
Solution Approach 1:
The patent employs feedback by continuously monitoring both pressure and position signals during lifting and lowering operations. The microprocessor uses this feedback information to calculate velocity and acceleration, then compensates for friction effects and dynamic contributions in real-time, enabling accurate weight determination without requiring manual constant speed operation.
Solution Approach 2:
The patent changes the approach from controlling speed to measuring and compensating for speed variations. Instead of maintaining constant speed as a control parameter, the system measures actual velocity and acceleration from position signals and compensates for their effects on the pressure measurements, thereby achieving accuracy without constant speed operation.
3Measurement precision
If a bi-directional flow controller is used to maintain constant flow, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent enables the hydraulic system to self-regulate flow during weighing operations. The bi-directional flow controller allows the system to automatically maintain substantially constant flow rates in both lifting and lowering directions without external control, using the inherent properties of the flow controller to balance viscous friction forces and eliminate the need for complex active control systems.
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 approach enables accurate weight determination with a simpler control system, reducing costs and minimizing measurement errors caused by friction and acceleration, while maintaining precision by balancing velocity-dependent viscous friction forces.
Implementation Method 1
limiting the flow of a hydraulic fluid through the hydraulic system by a bi-directional flow controller during the upward and downward displacement of the lifter
Implementation Method 2
a pressure in the hydraulic system is measured by means of a pressure sensor, thereby providing a pressure signal
Implementation Method 3
a parameter dependent on the position of the lifter is measured by means of a meter, thereby providing a position signal
Implementation Method 4
the lifter is displaced by means of a hydraulic actuator comprised by a hydraulic system
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~6
AI summary
A method of weight determination of a load carried by a lifter of a lifting device is based on at least one upward and one downward displacement of the lifter by means of a hydraulic actuator. A pressure signal is provided by means of a pressure sensor, and a position signal is provided by means of a meter. The weight of the load is determined on the basis of the pressure signal and the position signal. The position signal is registered as a function of time, an acceleration dependent parameter is determined on the basis of the variation of the position signal, and the weight de- termination is performed in dependence of said acceleration dependent parameter, where during the upward and downward displacement of the lifter, the flow of a hydraulic fluid through the hydraulic system is limited by a bi-directional flow controller. Furthermore, a weighing device is dis- closed.