Vacuum Pump Rotor Blade Fatigue Index for Replacement Timing
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Solution Overview
Problem
Current methods for determining the need to replace rotor blades in turbo-molecular vacuum pumps lack accuracy due to reliance on cumulative operation time alone, which does not account for varying gas loads and temperatures, leading to potential fatigue misjudgment and increased maintenance costs.
Innovation Solution
A vacuum pump system with sensors to measure rotor blade temperature and motor current, categorizing these measurements into predefined stages, tracking the time spent in each stage, and displaying or storing this data to objectively determine the necessity for rotor blade replacement, thereby providing a quantitative index for fatigue assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rotor blade replacement timing is determined based on cumulative operation time alone, then the determination method is simple, but the accuracy of fatigue assessment is insufficient
Solution Approach 1:
The patent transforms the single parameter of cumulative operation time into multiple parameters including cumulative operation time, maximum temperature, number of start-stop cycles, and gas load conditions. This multi-parameter approach enables comprehensive fatigue assessment while maintaining operational simplicity through automated indexing.
Solution Approach 2:
The patent introduces a fatigue index as an intermediary parameter that synthesizes multiple operational parameters (cumulative time, temperature, start-stop cycles, gas load) into a single quantitative measure. This index serves as a mediator between complex operational conditions and replacement decision-making, providing both accuracy and ease of use.
2Object-generated harmful factors
If the base portion temperature is raised to prevent product deposition, then deposition is reduced, but rotor blade temperature may exceed limit temperature under high exhaust load or high ambient temperature
Solution Approach 1:
The patent implements dynamic temperature control where the base portion temperature is adjusted based on real-time operational conditions such as exhaust load and ambient temperature. The system increases base temperature to prevent deposition when needed, but dynamically reduces it when rotor blade temperature approaches limits, resolving the contradiction between deposition prevention and overheating avoidance.
Solution Approach 2:
The patent employs feedback control mechanisms where temperature sensors monitor both base portion and rotor blade temperatures. The control system uses this feedback to automatically adjust heater power and water jacket flow rates, ensuring deposition prevention while maintaining rotor blade temperature within safe limits under varying operational conditions.
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 allows for accurate and timely determination of rotor blade replacement, reducing the risk of fatigue-related failures and optimizing maintenance schedules by using numerical values that reflect the operational conditions and gas deposit amounts within the pump.
Implementation Method 1
one of the sensors is a temperature measurement means for measuring a temperature of the rotor blade
Implementation Method 2
the other is a current amount measurement means for measuring a current amount of a current flowing through a motor which drives the rotor blade
Implementation Method 3
a heater or an annular water jacket pipe is wound around an outer periphery of a base portion or the like of the turbo-molecular pump
Implementation Method 4
control of heating by the heater or cooling by the water jacket pipe is performed based on a signal of the temperature sensor
Implementation Method 5
a radiation thermometer is installed in the base portion to constantly measure the temperature of the rotor blade
Data Source
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AI summary
Provided are a vacuum pump and a control device for a vacuum pump capable of accurately determining timing of rotor blade replacement by creating an index which allows a degree of fatigue of a rotor blade to be determined quantitatively and easily. A motor current value output from a motor drive control portion is input to a time count processing portion, and time in which a current value of a rotating body remains in a range of a stage is totalized for each stage of the current value in the time count processing portion. In addition, a rotor blade temperature value output from a rotor blade temperature measurement portion is input to the time count processing portion. Subsequently, a one-minute average value of the rotor blade temperature value acquired by sampling is calculated. Thereafter, for each stage of the rotor blade temperature value, time in which the average value remains in a range of the stage is totalized. Each time value obtained by the totalization in the time count processing portion is stored in a memory. In a storage data processing portion, data is read from the memory and is stored in a non-volatile memory.