Hydropneumatic Suspension Control for Mobile Crane Wheel Load Distribution
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Solution Overview
Problem
Hydropneumatic suspension systems in mobile cranes lack a direct relationship between the level and pressure in spring cylinders, leading to non-uniform wheel load distribution and potential overloading, which can cause instability and safety risks during road travel.
Innovation Solution
A method that uses pressure measurement sensors and a control unit to calculate and adjust pressure set values in spring circuits, ensuring that the pressures correspond to the center of gravity and weight of the crane, thereby achieving a uniform wheel load distribution by redistributing the pressures to maintain stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the mobile crane is levelled using preset suspension height set values, then the level and position are improved, but the wheel load distribution becomes non-uniform causing potential overloading
Solution Approach 1:
The control unit continuously monitors the actual pressures in the spring circuits using pressure measurement sensors and compares them with the calculated pressure set values. Based on this feedback, the control unit adjusts the pressures to achieve both the desired level position and uniform wheel load distribution, resolving the contradiction between level positioning and load distribution.
Solution Approach 2:
The system changes the pressure parameter in the spring circuits from fixed preset values to dynamically calculated values. The control unit calculates pressure set values based on the actual center of gravity position and weight, allowing the pressures to be adjusted to achieve both proper leveling and uniform wheel load distribution simultaneously.
2Reliability
If pressures are adjusted to achieve uniform wheel load distribution, then the reliability is improved, but the level position may deviate from preset values
Solution Approach 1:
The control unit uses feedback from both pressure measurement sensors and path measurement sensors to continuously monitor both the wheel load distribution (via pressures) and the level position. It dynamically adjusts the pressures to satisfy both requirements simultaneously, ensuring that uniform load distribution is achieved without compromising the preset level position.
Solution Approach 2:
The system transitions from static preset pressure values to dynamic pressure adjustment. The control unit continuously adapts the pressure set values based on real-time measurements of the center of gravity position and actual pressures, allowing the system to maintain both proper leveling and uniform wheel load distribution under varying operating conditions.
3Reliability
If pressure measurement sensors are used to calculate pressure set values, then the wheel load distribution is improved, but the device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it calculates pressure set values based on center of gravity data, monitors actual pressures via pressure measurement sensors, adjusts pressures to achieve uniform wheel load distribution, and maintains the preset level position. By making the control unit multi-functional, the patent avoids adding separate dedicated systems for each function, thereby limiting the increase in device complexity while achieving improved wheel load distribution.
4Reliability
If the pressures in spring circuits are readjusted based on detected pressures, then the wheel load uniformity is improved, but the time required for setup increases
Solution Approach 1:
The control unit calculates the pressure set values in advance based on the detected actual pressures and the desired uniform wheel load distribution. This preliminary calculation allows for quick adjustment without requiring iterative trial-and-error procedures, thereby reducing the time required for setup while achieving proper wheel load distribution.
Solution Approach 2:
The system uses feedback from pressure measurement sensors to quickly determine the actual pressures and calculate the required adjustments. This closed-loop feedback enables rapid convergence to the optimal pressure distribution, minimizing the time required for setup while ensuring uniform wheel load distribution is achieved.
Data Source
AI summary
A method for controlling a hydropneumatic suspension of a mobile crane having at least four wheels that are each allocated a spring cylinder, having at least four spring circuits in which at least one spring cylinder is incorporated in each case, each spring circuit being allocated a pressure measurement sensor and a path measurement sensor, in which signals of the pressure measurement sensors and of the path measurement sensors are processed by a control unit, and the spring cylinders are actuated. To optimize control of a hydropneumatic suspension for road travel operation of the mobile crane the mobile crane is levelled using preset suspension height set values of the spring circuits, then, in the control unit, on the basis of pressures detected by pressure sensors, pressure set values are calculated per spring circuit and pressures in the spring circuits are readjusted with the aid of pressure set values.