Vacuum Pump Rotor Temperature Monitoring via Magnetic Permeability
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Solution Overview
Problem
Conventional vacuum pumps face challenges in accurately monitoring rotor temperature using the Curie temperature of magnetic bodies due to signal distortion at low carrier frequencies and high sampling frequencies, leading to increased costs for high-frequency compliant DSPs or CPUs.
Innovation Solution
A vacuum pump design that employs a magnetic body with a Curie temperature within the monitoring range, an inductance detecting portion, and a carrier generation system, where the sampling frequency is set relative to the carrier frequency to reduce processing load, and includes averaging, differential, and signal correction means to improve temperature determination precision without increasing device cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the carrier signal frequency is set low, then the device cost is reduced, but the sensor signal becomes easily distorted by rapid magnetic permeability changes
Solution Approach 1:
The patent changes the parameter of carrier signal frequency from low to high to prevent signal distortion caused by rapid magnetic permeability changes during rotor rotation. This ensures reliable temperature monitoring while accepting the trade-off of higher processing requirements.
2Object-affected harmful factors
If the carrier signal frequency is set high, then signal distortion is prevented, but the sampling frequency must be high which requires expensive high-frequency compliant DSP or CPU
Solution Approach 1:
The patent applies preliminary filtering to the detected signal before digitalization, removing high-frequency components that contain distortion information. This allows the use of lower carrier frequencies and simpler processing components while still achieving accurate temperature monitoring.
3Measurement precision
If the sampling frequency is set high, then the sampling theorem is met for high carrier frequencies, but low frequency DSP or CPU cannot handle it
Solution Approach 1:
The patent extracts and removes high-frequency components from the detected signal through filtering before digitalization. This leaves only the essential temperature information at lower frequencies, enabling processing by low-frequency DSP or CPU while maintaining measurement precision.
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 solution allows for precise rotor temperature monitoring using the Curie temperature of magnetic bodies while preventing cost escalation by optimizing sampling and signal processing, ensuring accurate temperature determination without requiring expensive high-frequency processing components.
Implementation Method 1
a non-contact method for detecting the temperature of the rotor by using the phenomenon that the magnetic permeability of a ferromagnetic body greatly changes at the Curie temperature
Implementation Method 2
the change of the magnetic permeability of the magnetic body as an inductance change
Implementation Method 3
an inductance detecting portion facing the circle so as to establish a gap between the circle and the inductance detecting portion, the inductance detecting portion being configured to detect a change of magnetic permeability of the magnetic body as an inductance change
Data Source
AI summary
A vacuum pump includes at least one magnetic body located on a circle about a rotor rotational axis and having a Curie temperature within a rotor temperature monitoring range; an inductance detecting portion facing the circle so as to establish a gap between the circle and the inductance detecting portion, for detecting a change of magnetic permeability of the magnetic body as an inductance change when the magnetic body rotates; and a carrier generation device generating a carrier signal for providing in the inductance detecting portion. An A/D conversion device samples a detection signal of the inductance detecting portion synchronously with a carrier generation by the carrier generation device, and converts the detection signal to a digital signal. A determination device determines whether or not a temperature of the rotor exceeds a predetermined temperature, based on the change of the magnetic permeability of the magnetic body.