End Position Detection in Variable Hydraulic Machines
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Solution Overview
Problem
Existing hydraulic machines lack a reliable and cost-effective method to accurately detect when a displacement element has reached its end position, relying on expensive sensors that require calibration.
Innovation Solution
A method using an electrical measuring circuit with components that establish contact at end positions, detecting changes in electrical parameters such as current or voltage to indicate when the displacement element has reached its end position, incorporating components like resistors, capacitors, or inductors within the hydraulic machine's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are used to detect the end position of the displacement element, then the detection accuracy is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The patent replaces complex electronic sensors with a simple electrical contact system. Instead of using sensors that require calibration and complex electronics to detect the end position, the invention uses direct electrical contact between conductive elements when the displacement element reaches its end position. This mechanical-electrical contact system substitutes for the sensor-based detection system, achieving accurate end position detection without the complexity and cost of sensors.
Solution Approach 2:
The electrical contact system is self-calibrating and requires no external calibration procedures. The conductive elements are positioned such that contact occurs automatically at the predetermined end position, eliminating the need for manual sensor calibration. The system uses its own structural components (conductive elements integrated into the housing and displacement element) to perform the detection function, making the system self-sufficient.
2Reliability
If sensors are installed to detect end positions, then the reliability of end position detection is improved, but the manufacturing cost increases
Solution Approach 1:
The patent uses inexpensive electrical contact elements (conductive parts integrated into the housing and displacement element) instead of expensive sensors. These contact elements are simple conductive components that can be manufactured as integral parts of the hydraulic machine structure, significantly reducing material and manufacturing costs while maintaining reliable detection functionality.
Solution Approach 2:
The invention merges the structural components of the hydraulic machine (housing, displacement element) with the detection system by integrating conductive elements directly into these components. This eliminates the need for separate sensor assemblies and reduces the overall system cost by combining multiple functions into single components.
3Device complexity
If electrical contact components are integrated into the hydraulic machine structure, then the device complexity is reduced, but the measurement precision may be affected
Solution Approach 1:
The patent applies local quality by creating specific contact zones with precise geometric characteristics at the end position locations. The conductive elements are designed with specific surface areas, positions, and orientations to ensure that contact occurs only at the exact end positions. This localized precision in the contact regions maintains measurement precision despite the overall simplicity of the system.
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
Enables accurate and cost-effective detection of end positions without the need for expensive sensors, integrating the detection mechanism into the hydraulic machine's electronic control unit, ensuring reliable operation.
Implementation Method 1
whereby when the displacement element (4) reaches a particular end position an electrical contact is established between an electrical component (27a, 27b, 28a, 28b) assigned to the corresponding end position and an electrical measuring circuit (20)
Data Source
AI summary
The invention relates to a method and a device for determining of at least one end position of a displacement element of an adjustable hydraulic machine, in particular of the axial piston type, shiftable or displaceable between two ends position a by means of a displacement unit between a first end position and a second end position. According to the invention the determination of having reached an end position of displacement takes place by means of a measurement circuit, whose electrical characteristics are changed jumpily when an end position is reached. This is done by connecting a partial branch of the measuring circuit with earth, when a moveable element comes into electric contact with a limit stop assigned to the corresponding end position.