Hydraulic Control Unit Gain Factor Adjustment for Forklift Speed
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Solution Overview
Problem
Industrial trucks with automatic control of working hydraulics face non-reproducible speed behavior due to model deviations and environmental influences, leading to reduced performance and handling capacity, especially when maximum speeds are specified, and are affected by load pressure and hydraulic fluid temperature.
Innovation Solution
A method where basic characteristics for various operating points of the working hydraulics function are stored in a control unit, and an amplification factor dependent on load pressure and/or hydraulic fluid temperature is used to adjust these characteristics, creating a mathematical model relationship between the manipulated and control variables, thereby influencing static and dynamic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If standard control systems are used without feedback, then device complexity is reduced, but speed control precision deteriorates due to model deviations and environmental influences
Solution Approach 1:
The patent implements feedback control by continuously measuring the actual hydraulic function speed and comparing it with the reference speed. The control unit calculates a speed difference and adjusts the manipulated variable accordingly, creating a closed-loop control system that compensates for model deviations and environmental influences to maintain precise speed control.
2Reliability
If vehicles are designed to guarantee maximum speeds under all operating conditions, then reliability is improved, but productivity deteriorates due to reduced effective performance
Solution Approach 1:
The patent applies dynamic control by continuously adjusting the manipulated variable based on real-time feedback from actual speed measurements. This allows the system to optimize performance for each operating condition rather than being constrained by worst-case scenarios, enabling vehicles to achieve higher effective speeds while maintaining reliability through active compensation of deviations.
3Device complexity
If control systems do not compensate for environmental influences, then device complexity is reduced, but speed reproducibility deteriorates
Solution Approach 1:
The feedback control system measures actual speed and compares it with reference speed, automatically compensating for environmental influences such as temperature and load variations. This closed-loop approach ensures reproducible speed behavior across different operating conditions without requiring complex pre-programming for each scenario.
4Ease of operation
If manual adjustment of setpoint is required, then ease of operation is improved, but productivity deteriorates due to time consumption
Solution Approach 1:
The control system performs self-adjustment by automatically calculating the speed difference between actual and reference values and modifying the manipulated variable accordingly. This eliminates the need for manual operator intervention to correct speed deviations, maintaining ease of operation while significantly improving productivity through continuous automatic optimization.
Data Source
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AI summary
The invention relates to a method for controlling a working hydraulic function of a forklift truck (F) that is influenced by the load pressure of a load being lifted and/or by the temperature of a hydraulic fluid. A reference variable (w(t)) is specified, from which a manipulated variable (u(t)) is calculated in a control unit (C(s)). This manipulated variable determines a controlled variable (y(t)) of the working hydraulic function via a control path (G(s)). It is proposed that the control unit (C(s)) contains basic characteristic curves (Gk) for various operating points of the working hydraulic function, which establish a computational model relationship between the manipulated variable (u(t)) and the controlled variable (y(t)). The basic characteristic curves (Gk) in the control unit (C(s)) are adjusted via a gain factor (V) that depends on the load pressure (p) and/or the temperature (T) of the hydraulic fluid.