Centrifuge Speed Detection Using Pulse Interval Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional centrifuges face challenges in accurately detecting rotor rotational speed, especially in low-speed ranges, due to variations in pulse generation intervals, which can lead to significant errors and require structural modifications for improved detection.
Innovation Solution
A centrifuge system that utilizes a rotation detector generating multiple pulse signals per motor rotation, comparing time intervals between successive pulses to calculate rotational speed, and switches detection modes based on acceleration, constant speed, and deceleration phases, using either a photointerrupter or magnetic detection elements for precise speed measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotational speed is detected using pulse signals from an encoder in low-speed range, then speed detection is possible, but significant errors occur due to non-uniform pulse generation intervals
Solution Approach 1:
The patent changes the detection parameter from absolute pulse timing to time interval between pulses. By measuring the time interval between consecutive pulses and comparing it with the previous interval, the system can detect rotational speed changes even when absolute pulse timing varies, thereby improving reliability in low-speed range
Solution Approach 2:
The system uses feedback by comparing the current pulse time interval T(n,m) with the previous pulse time interval T(n-1,m). This comparative feedback mechanism allows the system to detect rotational speed changes while compensating for non-uniform pulse generation, improving measurement precision without requiring additional hardware
2Measurement precision
If a high-precision rotation detector is installed to improve detection accuracy, then rotational speed detection accuracy improves, but manufacturing cost increases due to structural modification
Solution Approach 1:
The patent makes the existing rotation detector serve a dual purpose: it continues to provide absolute position information while also providing pulse timing information for speed detection. By utilizing the existing detector's output signals in a new way (measuring time intervals between pulses), the system achieves improved accuracy without requiring additional detectors or structural modifications
Solution Approach 2:
The existing rotation detector is made multi-functional by using its pulse output for both position detection and speed detection. The same detector that originally served for position feedback now also provides timing information for rotational speed measurement, eliminating the need for separate speed detection hardware
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 enables stable and accurate rotational speed detection, even with non-uniform pulse signals, reducing errors and maintaining precision across varying speed ranges with minimal manufacturing costs.
Implementation Method 1
The rotation detector includes a disk attached to a rotation axis of the motor and for transmitting or blocking light, and a photointerrupter attached to a non-rotating part of the motor
Implementation Method 2
The rotation detector may include multiple magnets attached to the rotor, and a magnetic detection element attached to a non-rotating part near the rotor
Data Source
AI summary
In a centrifuge which employs a rotation detector for generating M-number (where M≥1) of pulse signals per rotation of a motor, a control unit compares a time interval T (n−1, m) of a pulse signal one rotation before an immediately preceding pulse detected by a rotation detector with a time interval T (n, m) of a recent detection pulse signal, and then, from an increase or decrease between the time interval T (n−1, m) and the time interval T (n, m), calculates the rotational speed by using a formula of rotational speed N (n, m)=N (n−1, m)×T (n−1, m)÷T (n, m).