Vacuum Pump Exhaust Purge Flow for Accurate Rotor Temperature Sensing
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Solution Overview
Problem
Conventional vacuum pump exhaust systems face challenges in accurately measuring the temperature of rotating portions due to low gas flow rates and pressure, leading to measurement errors and potential corrosion from process gases.
Innovation Solution
A vacuum pump exhaust system with a purge gas supply unit that regulates the flow rate and pressure of purge gas to ensure a higher velocity and intermediate or viscous flow around the temperature sensor, preventing backflow and ensuring accurate temperature measurement of the rotating portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If low flow rate purge gas is used, then gas consumption is reduced, but measurement accuracy deteriorates due to insufficient heat transmission
Solution Approach 1:
The patent changes the pressure parameter of purge gas to achieve intermediate flow or viscous flow state, which improves heat transmission capability without increasing gas flow rate. This allows accurate temperature measurement while maintaining low gas consumption.
Solution Approach 2:
The patent replaces reliance on high gas flow rate (mechanical flow) with thermal radiation and enhanced heat conduction mechanisms to transmit temperature information from the rotating portion to the sensor, enabling accurate measurement at low flow rates.
2Object-affected harmful factors
If low pressure purge gas is used, then gas backflow is prevented, but heat transmission becomes insufficient leading to measurement errors
Solution Approach 1:
The patent optimizes the pressure parameter of purge gas to achieve an intermediate state between molecular flow and viscous flow. This pressure optimization enables sufficient heat transmission through enhanced conduction and radiation while preventing harmful gas backflow to the sensor.
3Productivity
If high speed rotation is continued at high temperature, then productivity is maintained, but creep occurs reducing durability
Solution Approach 1:
The patent implements a feedback mechanism where the temperature sensor continuously monitors the temperature of the rotating portion and provides this information to the control unit. The control unit then adjusts operation to prevent excessive temperature accumulation, allowing sustained high-speed operation while preventing creep and extending durability.
4Speed
If non-contact temperature sensor is used, then high speed rotation measurement is enabled, but measurement accuracy deteriorates due to gas composition changes
Solution Approach 1:
The patent uses purge gas to create a stable, inert atmosphere around the temperature sensor and rotating portion. This prevents process gas contamination and maintains consistent gas composition in the measurement zone, eliminating measurement errors caused by variable gas properties while enabling non-contact temperature sensing during high-speed rotation.
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 system accurately measures the temperature of the rotating portion, prevents corrosion, and reduces measurement errors by maintaining a suitable gas flow and pressure, enhancing the durability and reliability of the vacuum pump.
Implementation Method 1
the temperature of the rotor blade is estimated according to a temperature difference caused by a heat quantity transmitted through purge gas
Implementation Method 2
a heat quantity may be insufficiently transmitted so as to increase errors of measurement by the temperature sensor
Implementation Method 3
it is necessary to measure the temperature by using a non-contact temperature sensor (temperature sensor unit)
Data Source
AI summary
A vacuum pump exhaust system and an exhausting method of the vacuum pump supply a purge gas to the vacuum pump such that an amount of the purge gas satisfies one of following conditions: an amount of the purge gas flowing at a higher velocity than a backflow velocity of gas exhausted by the vacuum pump on at least a part of a downstream side of the temperature sensor unit, and an amount of the purge gas having a pressure of one of an intermediate flow and a viscous flow around the temperature sensor unit. The exhaust system further includes a purge gas supply unit capable of controlling a flow rate of purge gas introduced into the vacuum pump. This configuration can prevent process gas from flowing backward so as to change the composition around the temperature sensor unit, thereby accurately measuring the temperature of the rotating portion.