Piston-Cylinder Position Sensing via Capacitance Frequency Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring the change in extension of piston-cylinder arrangements are either too complex, costly, and time-consuming, or require impractical conditions such as complete discharge and recharge, making them unsuitable for rapid and precise measurement in applications like motor vehicles.
Innovation Solution
A method involving an electrical circuit that applies a DC voltage to the piston-cylinder arrangement, senses capacitance, generates pulsed DC voltage, and measures frequency differences to determine displacement distance, allowing for rapid and precise measurement of extension changes without the need for complex AC circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC voltage and bridge circuits are used to measure extension change, then measurement precision is improved, but device complexity and measurement time increase significantly
Solution Approach 1:
The patent replaces complex AC bridge circuits with a DC voltage-based capacitor charging method. The piston-cylinder arrangement itself serves as the capacitor, and the charging time constant directly provides the extension change measurement, eliminating the need for complex AC measuring instruments and bridge circuits.
Solution Approach 2:
The piston-cylinder arrangement serves dual purposes: it performs its mechanical function while simultaneously acting as the capacitor for measurement. The system uses its own structural components (piston, cylinder, insulation) to form the capacitor, eliminating the need for separate measuring devices and reducing overall system complexity.
2Measurement precision
If AC voltage and bridge circuits are used to measure extension change, then measurement precision is improved, but measurement time becomes too long for practical use
Solution Approach 1:
The patent replaces time-consuming AC bridge measurements with a rapid DC capacitor charging method. The charging time constant can be measured in milliseconds, providing both high precision and rapid response suitable for real-time monitoring applications.
3Device complexity
If DC voltage with multimeter timing is used to measure extension change, then device complexity is reduced, but the requirement for complete discharge before recharge makes the method impractical
Solution Approach 1:
The patent incorporates a discharge resistor that continuously maintains the capacitor in a discharged state, eliminating the need for manual discharge operations before each measurement. This preliminary action ensures the system is always ready for measurement without requiring complete discharge cycles.
4Device complexity
If DC voltage with multimeter timing is used to measure extension change, then device complexity is reduced, but measurement precision and rapidity are insufficient
Solution Approach 1:
The patent changes the measurement parameter from simple time measurement with a multimeter to frequency measurement of oscillations. By measuring the frequency of oscillations generated during capacitor charging, the system achieves both high precision and rapid measurement while maintaining simple device complexity.
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 enables rapid sensing of extension changes in milliseconds, reducing readout time and eliminating the need for costly AC circuit components, while ensuring accurate measurements even during operation.
Implementation Method 1
sensing a capacitance of the piston-cylinder arrangement as an input variable for the electrical circuit unit
Data Source
AI summary
The invention relates to a method for measuring the position of a piston-cylinder arrangement, said method comprising: providing the piston-cylinder arrangement, providing an electrical circuit unit, applying a DC voltage (Vcc) to the piston-cylinder arrangement, sensing a capacitance (C) of the piston-cylinder arrangement as an input variable for the electrical circuit unit, generating a pulsed DC voltage (Vcc) by means of the electrical circuit unit on the basis of the sensed capacitance (C) of the piston-cylinder arrangement, providing a measuring unit for measuring a frequency (F0, F1) of the pulsed DC voltage (Vcc) generated, determining a frequency difference (DF) between the frequency (F0) of the pulsed DC voltage (Vcc) before displacement of the piston within the cylinder and the frequency (F1) of the pulsed DC voltage (Vcc) after displacement of the piston within the cylinder, determining a displacement distance of the piston within the cylinder on the basis of the frequency difference (DF).