Paver Screed Height Control via Displacement Sensor Feedback
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Solution Overview
Problem
Existing road finishers lack precise control over screed height adjustments due to independent operation of tow point adjustment controllers, leading to potential inaccuracies and oscillations, especially with wear or external forces affecting hydraulic systems, resulting in suboptimal paving quality.
Innovation Solution
Incorporation of displacement sensors coupled with a control unit to monitor and correct adjustment movements of actuating cylinders, ensuring plausibility and accuracy of tow point adjustments, and integrating with existing tow point adjustment controllers to manage sensitivity and external influences, thereby maintaining desired paving profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If independent tow point adjustment controllers are used on each side, then the screed height can be adjusted independently on left and right sides, but the control accuracy deteriorates due to lack of coordination and information sharing between controllers
Solution Approach 1:
The patent merges the two independent tow point adjustment controllers into a coordinated control system where both controllers communicate with a central control unit. The control unit receives signals from both controllers and coordinates their actions, allowing independent adjustment capability to be maintained while adding information sharing to improve control accuracy and prevent conflicts between left and right side adjustments.
Solution Approach 2:
The patent implements feedback mechanisms where displacement sensors provide real-time information about the actual position of towing points to the control unit. The control unit compares desired positions with actual positions and adjusts control signals accordingly, creating a closed-loop control system that significantly improves screed height control accuracy while maintaining independent adjustment capability.
2Speed
If high sensitivity is set in tow point adjustment controllers, then responsive adjustment is achieved, but constant oscillations occur due to excessive sensitivity
Solution Approach 1:
The control unit implements feedback from displacement sensors that continuously monitor the actual position of towing points. By comparing desired positions with actual positions and adjusting control signals dynamically, the system maintains high responsiveness while preventing oscillations through proportional control adjustments based on actual system state.
Solution Approach 2:
The control system uses periodic control signals with variable duration and amplitude based on the current deviation from target position. The control unit issues adjustment impulses of varying characteristics depending on the magnitude of height deviations, providing strong corrective action for large deviations while using smaller, more stable adjustments for fine-tuning, thus preventing oscillations.
Data Source
Figure 1~2
AI summary
The invention relates to a paver for the ground-side installation of layers for roads or the like., comprising a chassis and a trailing, floating installation screed articulated to it via drawbars, the angle of the screed being adjustable relative to the ground via an actuating cylinder arranged on each of the two sides of the chassis for adjusting the drawbar point of the drawbars, wherein a drawbar point adjustment controller is provided for each side for adjusting the drawbar point according to a predetermined installation height dimension of the installation screed, wherein displacement sensors are provided for measuring the adjustment movements of the actuating cylinders, which are coupled to a control unit that evaluates the adjustment signals of the drawbar point adjustment controllers, which detects the adjustment movements as control values and compares them with a target control value range for adjustment movements that can be stored in the control unit and corrects detected control values outside the target control value range to values within the target control value range.