Revolution indicator and a program for the revolution indicator

• US 20080106256A1
• Filed: 11/02/2007
• Published: 05/08/2008
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: ONO SOKKI (Thailand) Co. Ltd.
• Original Assignee: ONO SOKKI (Thailand) Co. Ltd.
• Inventors: Miyano, Tomio, Hori, Hideaki
• Granted Patent: US 7,890,271 B2
• Time in Patent Office: Days
• US Class Current: 324/166
• CPC Class Codes: G01P 3/44 for measuring angular speed G01P3/56 takes precedence
• CPC Class Codes: G01P 3/48 by measuring frequency of generated current or voltage in general G01R23/00

Abstract

The object of the invention is providing a revolution indicator and a program for the indicator, which can detect a varying number of revolutions precisely. The indicator includes: a detecting portion detecting a physical phenomenon resulting from the revolution movement of a measuring object; a FFT computation portion performing a fast Fourier transform of the data detected by the detecting portion under a specific data length, and computing and outputting the analytical data; and a revolution computing portion computing the number of revolutions of the measuring object based on the analytical data output from the FFT computation portion. A variation determination portion is equipped, which makes the FFT computation portion compute the first analytical data continuously, based on the data successively detected by the detecting portion under the first data length and determines whether there is any variation or not in the first analytical data computed continuously.

Claims

1. A revolution indicator, comprising:

a detecting portion which detects a physical phenomenon resulting from the revolving movement of a measuring object;

a FFT computation portion which performs a fast Fourier transform of the data detected by the detecting portion under a specific data length, and computes and outputs the analytical data; and

a revolution computing portion which computes the number of revolutions of the measuring object based on the analytical data output from the FFT computation portion, wherein

a variation determination portion is equipped, which makes the FFT computation portion compute the first analytical data continuously based on the data successively detected by the detecting portion under the first data length and determines whether there is any variation or not in the first analytical data computed continuously, and

when there is a variation in the first analytical data computed continuously, the variation determination portion makes the FFT computation portion output the first analytical data computed under the first data length to the revolution computing portion, and

when there is no variation in the first analytical data continuously computed, it makes the FFT computation portion compute the second analytical data under the second data length which is longer than the first data length and output to the revolution computing portion.

2. A revolution indicator according to claim 1, wherein the first analytical data is spectrum data, and wherein the variation of the first analytical data determined by the variation determination portion is the variation of frequency showing a maximum value of the spectrum data.

3. A revolution indicator according to claim 1, wherein the first analytical data is fast-Fourier-transformed with a lower number of sampling points than that of the second analytical data which is computed in the same frequency range.

4. A revolution indicator according to claim 2, wherein the first analytical data is fast-Fourier-transformed with a lower number of sampling points than that of the second analytical data which is computed in the same frequency range.

5. A revolution indicator according to claim 1, wherein the first analytical data is computed so that the data detected under the second data length is computed by the zero-suppress processing which leaves only a specific range of the data, making the others zero in order to perform the fast Fourier transform.

6. A revolution indicator according to claim 2, wherein the first analytical data is computed so that the data detected under the second data length is computed by the zero-suppress processing which leaves only a specific range of the data, making the others zero in order to perform the fast Fourier transform.

7. A program to make the revolution indicator execute the following steps, including:

a detecting step to detect a physical phenomenon resulting from the revolving movement of a measuring object;

a FFT computation step in which the detected data in the detecting step is fast-Fourier-transformed under a specific data length and the analytical data is computed and output; and

a revolution computing step to compute the number of the revolutions of the measuring object based on the analytical data output in the FFT computing step, wherein

the program for revolution indicator includes following steps;

a step to make the FFT computing step compute the first analytical data continuously under the first data length based on the data successively detected in the detecting step, and makes it execute a variation determination step to determine whether there is a variation or not in the continuously computed first analytical data, and

when there is a variation in the first analytical data computed continuously, the variation determination step makes the FFT computing step output the first analytical data computed under the first data length to the revolution computing step, and

when there is no variation in the first analytical data computed continuously, it makes the FFT computing step compute the second analytical data under the second data length which is longer than the first data length and output to the revolution computing step.