JPH0376427B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotational speed fluctuation measuring device for a rotating body that can be applied to a rotating shaft system torsional vibration measuring device and the like.

Various types of rotational speed fluctuation measuring devices have been considered in the past, and for example, a rotational speed fluctuation measuring device as shown in the block diagram of FIG. 1 is known. In Figure 1, 01 is a reference frequency oscillator, and this output signal is sent to the average period measurement counter 03.
is input. A rotation pulse signal A proportional to the rotational speed of the rotating body is further input to the average period measurement counter 03 via an average period setting switch 02. Reference numeral 04 denotes an instantaneous period measuring counter, and the output signal of the oscillator 01 and the rotation pulse signal A are respectively input to the input terminal of the counter 04. 05 is a difference calculation register, and the output signals of the counters 03 and 04 are input to its input terminals, and the output signal of register 05 is input to the D/A converter 06, and the rotation speed fluctuation is input from the D/A converter 06. It is configured so that signal B is output.

What is shown in FIG. 1 is a rotational pulse signal A proportional to the rotational speed of the rotating body detected using, for example, a gear provided on the rotating body and an electromagnetic pickup.
The number of oscillations of a high frequency reference frequency oscillator 01 using, for example, a crystal oscillator or the like is counted by counters 03 and 04 using as a gate signal.

The counter 03 closes the average period setting switch 02 when the rotating body is rotating at the rotation speed desired as a reference for measurement, and calculates and sets the average value of a given period number.

The count value of counter 03 is then changed to the above switch 02.
It is maintained without change until it is operated.

The counter 04 operates every period of the rotation pulse signal A and measures the instantaneous period.

The difference between this instantaneous period and the average period is determined by a difference calculation register 05, and this is converted into an analog signal by a D/A converter 06 and outputted as a rotational speed fluctuation output B.

To explain the above effects in more detail,
If the oscillator frequency of oscillator 01 is c and the frequency of rotation pulse signal A is i, then the count value of counter 04 is
Ni is calculated using the following formula.

Ni=c/i The count value of counter 03 obtained in the same way is No.
Then, the rotational speed variation D can be obtained by the following equation.

D = (Ni/No-1) x 100 = No-Ni/Ni x 100 (%) When this rotational speed fluctuation is sufficiently small compared to the average period, the rotational speed fluctuation will be the difference between the average period and the instantaneous period. Proportional.

Although the rotational speed variation measuring device shown in FIG. 1 is constructed as described above, this conventional device has a drawback in that sufficient measurement accuracy cannot be obtained for the following reasons. For example, when measuring torsional vibration of a turbine generator shaft system based on rotational speed fluctuations, the rotational speed fluctuation due to torsional vibration is 0.5% or less, and a measurement resolution of about 5/1000% is required. With conventional equipment, the measurement range needs to be set to be greater than the range of rotational speed changes in the rotating shaft system, and with turbine generators, the rotational speed changes by about 10% when the load is interrupted, so the measurement range needs to be set beyond this range. There is. Furthermore, when recording a measurement signal on an analog data recorder or the like, the dynamic range is about 50 dB, and the overall measurement accuracy is only about 3/100%, resulting in insufficient measurement accuracy.

The present invention was proposed in view of the above circumstances, and an object of the present invention is to provide a rotational speed fluctuation measuring device that can measure torsional vibration components with high accuracy even when the rotational speed of a rotating body fluctuates widely. The rotational speed fluctuation measuring device according to the present invention performs instantaneous period measurement by inputting a rotational pulse signal proportional to the rotational speed of a rotating body and an oscillation signal generated from a reference frequency oscillator, and counting the number of oscillations generated from the oscillator. a counter, a difference calculation register to which the output signal of the measurement counter is input to one input terminal, an integral register and a D/A converter to which the output signal of the difference calculation register is respectively input, and an output of the integral register. an average value calculation register that inputs a signal and constantly calculates an average period; the output signal of the average value calculation register is inputted to the other input terminal of the difference calculation register, and the output signal of the rotating body is inputted from the D/A converter. It is characterized in that it outputs a rotational speed fluctuation signal.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

In FIG. 2, 1 is a high-frequency reference frequency oscillator such as a crystal oscillator, and 2 is an instantaneous period measurement counter, which has an oscillation signal generated from the oscillator 1 and a rotation pulse signal A proportional to the rotation speed of the rotating body at its input terminal. are input respectively. Reference numeral 3 denotes a difference calculation register, and the output signal of the counter 2 is inputted to one input terminal thereof. 4 is an integral register to which the output signal of register 3 is input. Reference numeral 5 denotes an average value calculation register to which the output signal of the integral register 4 is input, and the output signal is sent to the register 3 above.
is input to the other input terminal of . Reference numeral 6 denotes a D/A converter, into which a part of the output signal of the register 3 is branched and inputted, and the rotational speed fluctuation signal B is outputted from its output end. Reference numeral 7 denotes another D/A converter, to which a part of the output signal of the register 5 is branched and input, and the average rotational speed signal C is outputted from its output terminal.

Next, the operation of the embodiment of the present invention shown in FIG. 2 will be described. The number of oscillations of the oscillator 1 is counted by the counter 2 using the rotation pulse signal A as a gate signal. The difference between this count value and the average period is determined by the difference calculation register 3, and its output signal is input to the D/A converter 6, which causes the output terminal of the D/A converter 6 to output a rotational speed fluctuation signal B. On the other hand, the output signal of the difference calculation register 3 is integrated by the integration register 4, and divided by a constant set in the average value calculation register 5 to constantly obtain the average period. The average rotational speed is determined from this average period, and this output signal is input to the D/A converter 7, which outputs an average rotational speed signal C from its output terminal.

Since the present invention is configured as described above, the following excellent effects can be achieved.

(1) Since the average period is always calculated using the difference calculation register 3, the integral register 4, and the average value calculation register 5, even if the rotation speed of the rotating body fluctuates widely, the average value will not change to this value. The measurement range can be kept small.

(2) By changing the constant of the average value calculation register 5, the time constant of average value tracking can be changed.

In summary, the present invention includes an instantaneous period measuring counter that receives a rotation pulse signal proportional to the rotation speed of a rotating body and an oscillation signal generated from a reference frequency oscillator, and counts the number of oscillations generated from the oscillator; A difference calculation register to which the output signal of the measurement counter is input to one input terminal, an integral register and a D/A converter to which the output signal of the difference calculation register is respectively input, and an output signal of the integral register is input. and an average value calculation register that constantly calculates an average period, and the output signal of the average value calculation register is inputted to the other input terminal of the difference calculation register, and the rotational speed fluctuation of the rotating body is input from the D/A converter. The present invention provides a rotational speed variation measuring device that can measure torsional vibration components with high accuracy even if the rotational speed of a rotating body varies widely by outputting a signal, and therefore, the present invention is applicable to industrial applications. Above all, it is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional rotational speed fluctuation measuring device, and FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. 1...Reference frequency oscillator, 2...Instantaneous period measurement counter, 3...Difference calculation register, 4...Integration register, 5...Average value calculation register, 6, 7...
...Each D/A converter, A...Rotation pulse signal, B...
...Rotation speed fluctuation signal, C...Average rotation speed signal.

Claims (1)

[Claims] 1. An instantaneous period measurement counter that inputs a rotation pulse signal proportional to the rotation speed of the rotating body and an oscillation signal generated from a reference frequency oscillator and counts the number of oscillations generated from the oscillator, A difference calculation register to which the output signal of the measurement counter is input, an integral register and a D/A converter to which the output signals of the difference calculation register are respectively input, and a constant average period is calculated by inputting the output signal of the integral register. an average value calculation register, the output signal of the average value calculation register is input to the other input terminal of the difference calculation register, and the rotational speed fluctuation signal of the rotating body is outputted from the D/A converter. A rotational speed fluctuation measuring device characterized by: