Rotor Shaft Axial Position Detection Using Ferromagnetic Sensor Ring
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Solution Overview
Problem
Existing devices for detecting the axial position of a rotor shaft in rotary machines are not compatible with hollow shafts or those where the center is used to attach tools, and they require specific targets, increasing complexity and cost, while punctual sensing solutions are unsatisfactory for large diameters and can generate vibrations due to rotational harmonics.
Innovation Solution
A device with a sensor stator ring made from ferromagnetic material, secured to the stator, which senses the axial position of the rotor shaft shoulder without an additional target, using two parallel annular induction coils connected in series to concentrate magnetic excitation flux and an electrical circuit with a capacitor and AC voltage source to detect airgap modifications, allowing for direct sensing of the rotor shaft's axial position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a specific ferromagnetic target is secured to the rotor shaft end, then the axial position can be detected, but the device complexity and cost increase
Solution Approach 1:
The rotor shaft itself serves as the magnetic target through its shoulder structure, eliminating the need for separate ferromagnetic targets. The shaft's own magnetic properties and geometry are utilized for position sensing, making the system self-sufficient and reducing component count
Solution Approach 2:
The rotor shaft shoulder serves dual purposes: structural support function and position sensing target. This multi-functionality eliminates the need for dedicated sensing components while maintaining accurate axial position detection
2Measurement precision
If a specific ferromagnetic target is secured to the rotor shaft end, then the axial position can be detected, but the cost increases
Solution Approach 1:
The rotor shaft itself serves as the magnetic target through its shoulder structure, eliminating the need for separate ferromagnetic targets. The shaft's own magnetic properties and geometry are utilized for position sensing, making the system self-sufficient and reducing component count
Solution Approach 2:
The invention eliminates expensive specialized components by using the existing rotor shaft structure for sensing purposes, reducing overall system cost while maintaining functionality
3Measurement precision
If punctual sensing solutions are used to sense the axial position of the rotor shaft shoulder, then the detection can be implemented, but rotational harmonics appear on the sensor signal generating vibrations
Solution Approach 1:
The invention transitions from punctual (point) sensing to annular (ring-shaped) sensing. The annular induction coil distributes the sensing area around the rotor shaft, transforming the sensing geometry from one-dimensional point contact to two-dimensional annular contact, which eliminates rotational harmonics
4Adaptability or versatility
If the center of the rotor shaft is used to attach tools or turbine wheels, then the application requirements are met, but the axial position detection becomes incompatible
Solution Approach 1:
The invention transitions from punctual (point) sensing to annular (ring-shaped) sensing. The annular induction coil distributes the sensing area around the rotor shaft, transforming the sensing geometry from one-dimensional point contact to two-dimensional annular contact, which eliminates rotational harmonics
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 detection of the axial position of the rotor shaft without additional targets, reduces complexity and cost, provides clear signals without rotational harmonics, and allows access to the center of large rotor shafts, making the system more compact and robust.
Implementation Method 1
a sensor stator ring (31) made from ferromagnetic material, secured to the stator, made from ferromagnetic material, facing one end of the rotor shaft and arranged in a stationary manner so as to leave an axial airgap with the one end of the rotor shaft shoulder. The sensor stator ring provides at least one annular slot receiving an annular induction coil.
Implementation Method 2
The sensor stator ring (31) made from ferromagnetic material, secured to the stator, made from ferromagnetic material, facing one end of the rotor shaft and arranged in a stationary manner so as to leave an axial airgap with the one end of the rotor shaft shoulder.
Implementation Method 3
an electrical circuit for powering the induction coils, the electrical circuit comprising a first AC voltage source connected to a first end of the set of coils connected in series, and at a point located at a reference voltage, and a capacitor connected in parallel to the set of coils, to the first and second end of the set of coils, and an AC current detector device arranged between the second end of the set of coils and the reference voltage adapted to deliver information about the magnitude of the current flowing
Data Source
AI summary
A device for detecting the axial position of a rotor shaft of a rotary machine having a stator and a rotor is provided. The detecting device includes a sensor stator ring, secured to the stator, made from ferromagnetic material, facing the shoulder of one end of the hollow or not hollow rotor shaft and arranged so as to leave an axial airgap with the one end of the rotor shaft. The sensor stator ring having at least one annular slot receiving an annular induction coil. The rotor shaft is made from solid magnetic steel, an outer end of the rotor shaft acts as a target surface whose axial position is to be measured by the sensor stator ring.