Axial Piston Unit Linkage With Elastic Overload Decoupling
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Solution Overview
Problem
Hydrostatic variable displacement axial piston units with rigid linkage elements face challenges in adapting to changing loads, leading to increased force requirements and mechanical feedback, which can cause engine stalling and inefficiency due to deviation from the designed torque-speed ratio.
Innovation Solution
A displacement volume setting device with an elastically deformable connecting element that decouples input and output coupling elements when forces exceed a predetermined threshold, allowing the tilt angle to adjust and preventing engine overload, while maintaining efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rigid linkage elements are used to connect the input device to the displacement element, then direct mechanical connection and precise control are achieved, but the force required to hold the linkage increases and mechanical feedback signals are generated
Solution Approach 1:
The connecting element changes its mechanical parameter (rigidity) based on the load conditions. Under normal operating conditions, it maintains a rigid connection for precise control. When the force from the displacement element exceeds the predetermined threshold, it elastically deforms to absorb excess force, thereby reducing the force required to hold the linkage while maintaining operational precision.
2Power
If the tilt angle of the displacement element is adjusted to adapt to increasing load, then the hydraulic power output increases, but the rotational speed of the combustion engine decreases which can lead to engine stalling
Solution Approach 1:
The elastically deformable connecting element acts as an intermediary between the operator's input device and the displacement element. When the hydraulic unit generates excessive torque that could stall the engine, the connecting element elastically deforms, decoupling the input device from the displacement element. This allows the displacement element to maintain its tilt angle and power output while preventing the excessive torque from being transmitted back to the engine through the control mechanism, thus avoiding engine stalling.
3Power
If the displacement volume is increased to provide more hydraulic power, then the torque-speed ratio deviates from the designed ratio, but the engine efficiency decreases
Solution Approach 1:
The system implements mechanical feedback through the connecting element that monitors the force or torque generated by the hydraulic unit. When the torque exceeds the predetermined threshold, the elastic deformation of the connecting element provides feedback that decouples the control input from the displacement element, preventing further increase in displacement volume. This feedback mechanism ensures the engine operates within its efficient torque-speed ratio range while still allowing the hydraulic unit to deliver the necessary power when needed.
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
The solution enables the hydrostatic unit to maintain target operating conditions by adjusting displacement volume and reducing torque requirements, preventing engine stalling and improving efficiency under varying loads.
Implementation Method 1
the connecting element is elastically deformable if a force resulting from a high-pressure level which is present at/in the hydrostatic variable displacement axial piston unit exceeds a predetermined threshold value
Data Source
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AI summary
Disclosed is a displacement volume setting device of a hydrostatic variable displacement axial piston unit comprising an input device for providing a displacement command. Displacement volume adjusting means set the tilt angle of a displacement element according to the displacement command. A linkage element comprises an input coupling element connected to the input device, an output coupling element connected to the displacement volume adjusting means, and a connecting element. The input coupling element and the output coupling element are connected by the connecting element which is elastically deformable if a force resulting from the high pressure level present at the hydrostatic axial piston unit and acting on the output coupling element exceeds a predetermined threshold value. Also disclosed is a hydrostatic variable displacement axial piston unit.