RF Sensor for Rock Drill Piston Position Sensing
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Solution Overview
Problem
Existing rock drilling machines lack accurate sensing of the position of displaceable elements, such as pistons, due to limitations in existing sensor technologies which are not robust enough to handle high pressures and harsh environments, and cannot provide precise control over drilling operations.
Innovation Solution
A Rock Drill Sensing Device utilizing an RF sensor element that is insensitive to high pressures, capable of operating at high frequencies, and can accurately determine the position of displaceable elements by influencing an RF field, allowing for precise control of drilling operations through evaluation of resonance frequency or amplitude changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional sensor is used to detect piston position, then the device structure is simple, but the sensor cannot withstand high pressures and harsh environments
Solution Approach 1:
The patent replaces traditional mechanical contact sensors with an RF sensor system that uses electromagnetic fields to detect piston position. The RF sensor element generates an RF field that interacts with the conductive piston, allowing position detection without mechanical contact or exposure to high-pressure environments, thereby achieving both reliability and pressure resistance.
2Measurement precision
If an RF sensor element is used to accurately detect position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The RF sensor element serves multiple functions: it acts as both the sensing element and the signal source, while also functioning as an antenna for transmitting and receiving RF signals. This multi-functionality reduces the need for separate components, thereby maintaining measurement precision while limiting the increase in device complexity.
Solution Approach 2:
The system uses RF field interactions to create an indirect measurement of piston position, effectively copying the position information through electromagnetic field disturbances rather than direct mechanical measurement, which simplifies the physical sensing mechanism while maintaining accuracy.
3Measurement precision
If the RF sensor element extends along the axial direction, then measurement precision is improved, but the sensor occupies more space
Solution Approach 1:
The RF sensor element is positioned radially adjacent to the piston rather than extending axially along it. This radial positioning in a different spatial dimension allows the sensor to detect axial piston movements through RF field interactions without occupying significant axial space, thereby maintaining measurement precision while minimizing volume occupation.
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 RF sensor device provides robust and accurate positioning information, enabling precise control of rock drilling machines, minimizing calibration issues and allowing for efficient monitoring and control of piston movement, impact speed, and stroke length, even in hostile environments like air and oil.
Implementation Method 1
the RF-sensor element (4) can be said to be arranged to work as an antenna, whereby the displaceable element (2) influences the RF field of the RF sensor element (4) in dependence of their relative position and/or relative speed
Implementation Method 2
Such a parameter signal could for example be a resonance frequency of an RF sensor element resonance circuit, since such a resonance frequency would depend on structures adjacent to the RF sensor element
Implementation Method 3
the RF-sensor element (4) could be of capacitive type, whereby the sensor element could be adapted to react to an electrical permittivity of an adjacent object
Implementation Method 4
the RF-sensor element (4) could be of inductive type, whereby the sensor element could be adapted to react to a magnetic susceptibility of an adjacent object
Data Source
Figure 1
Figure 2~3
Figure 4~7b
AI summary
Device and method for sensing a parameter related to a position of a displaceable element (2) which is movable in an axial direction inside a housing (1) of a rock drilling machine, wherein said device includes a sensor element (4) which is located in a housing part. The sensor element (4) is an RF sensor element which is positioned adjacent to, along and sideways of a path of movement of the displaceable element (2). The invention also concerns a sensor element and a rock drilling arrangement.