Electrohydraulic Lift Lowering Pressure Control With Area-Ratio Feedback
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Solution Overview
Problem
Existing electro-hydraulic power lifts face challenges in accurately controlling lowering pressure, particularly due to differences in effective areas between lifting and lowering sides, leading to inefficiencies and potential over-pressing during load handling.
Innovation Solution
The method involves continuous determination of equivalent lowering pressure by calculating the difference between lifting and lowering pressures, using an electronic control unit to adjust the pressure valve based on the ratio of effective areas, and incorporating volume flow compensation to prevent over-pressing, with optional filtering and shut-off mechanisms to manage pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure control valve is used to regulate lowering pressure, then lowering pressure control is improved, but pressure accuracy deteriorates due to flow-related pressure drops
Solution Approach 1:
The system continuously measures the actual lowering pressure via a pressure sensor and feeds this information back to the electronic control unit. The control unit compares the measured pressure with the target pressure and dynamically adjusts the control signal to the pressure control valve, creating a closed-loop feedback system that compensates for pressure drops and maintains accurate pressure control.
Solution Approach 2:
The patent replaces traditional mechanical pressure regulation mechanisms with an electronically controlled pressure control valve actuated by an electronic control unit. This substitution allows for more precise and dynamic control of the lowering pressure by using electronic signals instead of purely mechanical adjustments, enabling real-time compensation for flow-related pressure drops.
2Measurement precision
If effective area ratio compensation is implemented, then lowering pressure control is improved, but control complexity increases
Solution Approach 1:
The system compensates for the effective area ratio between lifting and lowering sides by dynamically adjusting the target lowering pressure parameter. The electronic control unit calculates the equivalent lowering pressure by multiplying the lifting pressure by the effective area ratio (A1/A2) and uses this compensated value as the control target, thereby accounting for the geometric differences in the hydraulic system.
Solution Approach 2:
The electronic control unit acts as an intermediary that processes the relationship between lifting pressure and lowering pressure through the effective area ratio. It calculates the equivalent lowering pressure and uses this intermediate value to control the pressure control valve, mediating the complex relationship between the two sides of the hydraulic system.
3Reliability
If continuous pressure monitoring is implemented, then safety is improved, but energy consumption increases
Solution Approach 1:
The pressure sensor continuously monitors the lowering pressure, and the electronic control unit periodically updates the control signal to the pressure control valve based on the monitored pressure. This periodic control action ensures safety through continuous monitoring while managing energy consumption by only actuating the valve when pressure adjustments are needed, rather than maintaining constant high-energy operation.
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 ensures precise control of lowering pressure, preventing over-pressing and optimizing hydraulic energy use by adjusting the pressure valve according to calculated equivalent sink pressures and volume flow, enhancing the overall efficiency and safety of load handling.
Implementation Method 1
a first pressure sensor (19) for detecting the lifting pressure and a second pressure sensor (20) for detecting the lowering pressure
Implementation Method 2
an adjustable pressure valve (35) for setting a lowering pressure
Implementation Method 3
pressure medium is supplied to the base side cylinder chamber (13) for lifting and to the rod side cylinder chamber (14) for lowering
Data Source
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AI summary
The invention relates to a method for controlling the lowering pressure of an electro-hydraulic power lift, which has a working cylinder with a piston, a lifting side bounded by the piston with a lifting-side working surface, and a lowering side bounded by the piston with a lowering-side working surface. The electro-hydraulic power lift also comprises a first pressure sensor for detecting the lifting pressure and a second pressure sensor for detecting the lowering pressure, an adjustable pressure valve for setting a lowering pressure, and an electronic control unit.To improve the functionality of the electro-hydraulic power lift, the following process steps are provided: Continuous determination of an equivalent lowering pressure by calculating the difference between the lifting pressure multiplied by k (minuend) and the lowering pressure (subtrahend) in the electronic control unit, where k is the ratio of the size of the lifting-side effective area to the size of the lowering-side effective area of the piston; calculation of a pressure value as the difference between a target pressure set on the lowering side (minuend) and the equivalent lowering pressure (subtrahend); and activation of the pressure valve with a control signal corresponding to the pressure value.