Method of speed measure on turbo superchargers of internal combustion engines by means of vibrations analysis and equipment to perform it

• US 7,283,923 B2
• Filed: 02/28/2006
• Issued: 10/16/2007
• Est. Priority Date: 07/18/2005
• Status: Expired due to Fees

• Current Assignee: Alberto Eduardo Torres, Barilá, Daniel Oscar, Fernando Martin Vignolo, Gerardo Daniel Ahrtz, Gustavo Gabriel Vignolo, Luis Arturo Bugna, Münnemann, Alejandro Federico, Pedro Daniel Kolodka
• Original Assignee: Alberto Eduardo Torres, Barilá, Daniel Oscar, Fernando Martin Vignolo, Gerardo Daniel Ahrtz, Gustavo Gabriel Vignolo, Luis Arturo Bugna, Münnemann, Alejandro Federico, Pedro Daniel Kolodka
• Inventors: Vignolo, Fernando Martin, Kolodka, Pedro Daniel, Torres, Alberto Eduardo, Barilá, Daniel Oscar, Bugna, Luis Arturo, Münnemann, Alejandro Federico, Ahrtz, Gerardo Daniel, Vignolo, Gustavo Gabriel
• Primary Examiner(s): Barlow; John
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US11/365,204
• Publication Number:
  US 20070016385A1
• Time in Patent Office: 595 Days
• Field of Search: 702142-147, 702/198, 702/96, 702/126, 702/56, 702 76- 77, 123/192.1, 701100-101, 701110-111, 701/115, 73660-662, 735/70, 73/66, 735/79, 603/22
• US Class Current: 702/142
• CPC Class Codes: F02B 39/16 Other safety measures for, or other control of, pumps
• CPC Class Codes: G01P 3/44 for measuring angular speed G01P3/56 takes precedence

Abstract

A method of determining speed of rotation of a motor is provided. The method involves collecting samples with a measuring sensor at a sampling frequency, set on the basis of mechanical vibration of the motor, for the duration of a measurement period and storing the samples in the memory of a data carrier as measurement data of a fixed format. The speed of rotation of the motor is determined from the measurement data by determining the cycle length of a periodic vibration signal in the time domain by a maximum likelihood estimate calculated by maximizing a maximum likelihood function adjusted to the measurement data, the speed of rotation being obtained from the frequency point where the maximum likelihood function obtains its maximum value.

Claims

1. Method of speed measure on a turbo supercharger of an internal combustion engine by means of vibrations analysis, comprising the steps of:

measuring vibrations in said turbo supercharger, said measuring step comprising

(a) incorporating software for data processing to integrate measuring equipment to a ROM memory of a computer;

(b) connecting a vibration sensor to the measuring equipment and displaying the vibration sensor on a frame of a turbo-compressor;

(c) entering into the measuring equipment, the number of blades of a turbo supercharger turbine and then, a number of blades of the turbo supercharger compressor;

(d) initiating measuring and digitalizing of N samples of an entrance signal and storing the samples in a RAN memory;

(e) obtaining frequency spectrum components of a vibration signal measured by means of FFT;

(f) obtaining a PE function which together with the FFT function allows determination of a harmonic correlation function applying the following expression;

$\begin{array}{cc}\mathrm{CA}<br><br>\left(x\right)=\mathrm{The}<br><br><br><br>\mathrm{biggest}<br><br><br><br>\mathrm{of}<br><br><br><br>\langle <br><br>{\mathrm{CA}<br><br>\left(x\right)}_k\rangle <br><br>=\underset{i=1}{\overset{n}{\prod <br><br>}}<br><br>E<br><br>\left(i·<br><br>x+k·<br><br>i/n\right)·<br><br>\mathrm{PE}<br><br>\left(i\right)& \left(9\right)\end{array}$

Where;

k=is a value between 1 and n,

CA(x)=Harmonic Correlation Function,

E(x)=Spectrum Function, calculated with a TRF of the sensed signal,

PE=Spectral Comb Function,

n=Number of harmonic to consider,

x=Frequency of a value between 0 and a maximum frequency obtained in the FFT; and

(g) obtaining RPM starting from a frequency corresponding to a maximum value of the CA function.

2. The method of claim 1, wherein said second number entering step comprises entering a second number which is one-half of the number of compressor blades in the event said compressor has short and long blades.

3. The method according to claim 1, wherein obtaining of the harmonic correlation function CA is performed using the following expression:

$\begin{array}{cc}\mathrm{CA}<br><br>\left(x\right)=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br>E<br><br>\left(i·<br><br>x\right)·<br><br>\mathrm{PE}<br><br>\left(i\right)& \left(1\right)\end{array}$

Where;

CA(x)=Harmonic Correlation Function

E(x)=Spectrum Function, calculated with the FFT of the sensed signal

PE=Spectral Comb Function

n=number of harmonics to consider

x=Frequency which varies between zero and the maximum frequency obtained by FFT.

4. The method according to claim 1, wherein the obtaining of the harmonic correlation function CA is performed using the following expression:

$\begin{array}{cc}\mathrm{CA}<br><br>\left(x\right)=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br>E<br><br>\left(i·<br><br>x\right)·<br><br>\mathrm{PE}<br><br>\left(i\right).& \left(3\right)\end{array}$

5. The method according to claim 1, wherein the obtaining of the harmonic correlation function CA is performed using the following expression:

$\begin{array}{cc}\mathrm{CA}<br><br>\left(x\right)=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br>\left(\underset{j=-m}{\overset{m}{\sum <br><br>}}<br><br>E<br><br>\left(i·<br><br>x+j\right)\right)·<br><br>\mathrm{PE}<br><br>\left(i\right)& \left(5\right)\end{array}$

Where;

j=increase by steps of sampled values m=half width of a strip to consider.

6. A method of speed measure on a turbo supercharger of an internal combustion engine by means of vibrations analysis, comprising the steps of:

measuring vibrations in said turbo supercharger comprising

(a) incorporating software for data processing to integrate a measuring equipment to a ROM memory of a computer;

(b) connecting an acceleration sensor to the measuring equipment and displaying said sensor in respect to a collecting frame of a compressor;

(c) entering into the measuring equipment the number of blades of the turbo supercharger turbine and then, a number of blades of the turbo supercharger compressor, and a total number of blades of the compressor in order to build spectral comb function PE;

(d) initiating the measuring and digitalizing of N samples of an entrance signal and storing the samples in a RAM memory;

(e) obtaining frequency spectrum components of a vibration signal measured by means of EFT;

(f) obtaining a harmonic correlation function CA by applying an algorithm forming said software; and

(g) determining a component of a highest amplitude.

7. A computerized system for implementing a method of speed measure on a turbo supercharger of an internal combustion engine by means of vibrations analysis, said system comprising:

a computer having a ROM memory with means for generating by applying Fourier'"'"'s transformation (FFT) a spectrum of frequencies from “

N”

registered data;

means for generating a “

spectral comb”

function from a fundamental component of a frequency and its “

n”

harmonics, means for introducing a quantity of blades of a certain turbine and compressor;

means for processing both spectrum of vibration of a measured signal and a “

spectral comb”

function by means of a “

CA”

(harmonic correlation) algorithm and detecting a spectral component of maximum amplitude; and

means for converting the maximum value of “

CA”

frequency obtained to “

RPM”

; and

a vibration sensor connected to said computer.

8. Equipment for performing a method of speed measure on a turbo supercharger of an internal combustion engine by means of vibrations analysis comprising:

at least one sensor;

a conditioning device for Analogical signals coming from the at least one sensor;

an anti-aliasing, programmable low pass filter;

an analog-digital converter with programmable sampling frequency;

a digital signals processor that contains in a programs memory a plurality of algorithms including FFT, auto spectrum and harmonic correlation;

a memory bank of pre signal processing to store acquired samples;

a digital screen for presenting results and for introducing configuration parameters;

a program memory containing all digital functions for implementing a method of harmonic correlation; and

a communication port.

9. The equipment according to claim 8, wherein said at least one sensor comprises at least one of an acceleration sensor, a speed sensor, and a laser vibration technology sensor.

10. The equipment according to claim 8, wherein the at least one sensor comprises a vibration sensor and further comprising a signal conditioning device including an electronic analogical circuit adaptor of tension (voltage) or load (charge) levels coming from the vibration sensor whose output provides a signal with an appropriate range of tension (voltage) for input to the filter and the converter.

11. The equipment according to claim 8, wherein the anti-aliasing low pass filter has a programmable cut frequency and a diminishing slope in a −

24 dB per octave passing band.

12. The equipment according to claim 8, wherein the analog-digital converter with programmable sampling frequency acquires a sample of an analog signal, quantifies said analog signal and codes said analog signal in a digital binary value of 12 bits.