JPH01244309A - Eccentricity amount measuring circuit of rotary shaft - Google Patents

Abstract

PURPOSE:To prevent the indication of the eccentricity amount from changing even when an output signal indicating said eccentricity amount is changed by external disturbances, by selecting signals of a lower level one from those two, i.e. the measured output signals of eccentricity amount and outputted signals of eccentricity amount from a sample hold circuit. CONSTITUTION:A first peak hold circuit 4 and a second peak hold circuit 5 hold a peak value of electric signals indicating the eccentricity amount of a rotary shaft 6. A signal selecting circuit 9 compares outputs V1, V2 of the respective peak hold circuits 4, 5, and generates the output signals of a higher level as Vout. A sampling pulse generator 8c generates a sampling pulse Vr3 every time it detects a protrusion 7 on the rotary shaft 6. A sample hold circuit 13 holds the output of the selecting circuit 9 by the sampling pulse Vr3. A lower level selecting circuit 14 selects an output of a lower level one from those two, i.e. the outputs from the selecting circuit 9 and sample hold circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a rotating shaft eccentricity measuring circuit for measuring the eccentricity of a C rotating shaft of a turbine generator or the like.

[Conventional technology]

FIG. 5 shows an eccentricity measuring circuit shown in, for example, Japanese Patent Publication No. 5'6-48802. This eccentricity measuring circuit has a peak-to-peak amplitude detection circuit (1) connected to a protrusion (6) on the rotating shaft (6). 7
), and generate reset pulse signals Vrl and Vr2 synchronized with the rotation period, respectively, and a peak hold circuit (4).
), the third peak hold circuit (5) holds the peak value of the eccentricity signal Vl of A signal selection circuit (9) comprising diodes (10), (11) and a resistor (12) for selecting the first and second signals.
The peak hold circuits (2) and (4) are reset by the reset pulse signal Vrl in a state where the third peak hold circuit (5) holds the eccentricity signal of the measurement period, and the third peak hold circuit (5) is reset by the reset pulse signal Vrl. 5) is reset in a state in which the second peak hold circuit (4) is generating an eccentricity signal for the next measurement cycle.

a z f in FIG. 6 is a waveform diagram of each part for explaining the circuit operation of FIG. 5, and the input signal Vin to the peak-to-peak amplitude detection circuit (1) is shown in a of FIG. 6. has been done. Reset pulse signals Vrl and Vr2 as shown in FIG. 6, a and c, respectively, are generated in synchronization with the rotation period of the rotating shaft, and first, as shown in FIG. The third peak hold circuit (5) that is holding the peak is reset, and this circuit (5)
) peak-holds the signal v1 again, then d in Figure 6
As shown in , the reset pulse signal Vrl resets the first and second peak hold circuits (2) and (4). Output v that holds the signal v1 of the previous cycle
2 is generated from the hold circuit (5), the peak hearing loss width detection circuit (1) generates the eccentricity amount signal v1 of the next cycle. The signal selection circuit (9) selects the signal v2 which is at a high level among the signals v1 and v2, and produces an output Vout as shown at f in FIG. Thereafter, the same operation is repeated as the peak-to-peak amplitude of the input signal Vin decreases, and the output V
out follows the decrease in the human input signal with a delay of one cycle,
The overall result is as shown in Fig. 6(f).

[Problem to be solved by the invention]

Conventional eccentricity measurement circuits are configured as described above, so when measuring the eccentricity of a turbine generator, for example, the distance between the eccentricity detection sensor and the object to be measured (rotating shaft) is stepped due to thermal expansion of the turbine. 7, the offset amount Va, which is the DC component of the eccentric input signal Vin, also changes stepwise. As the offset amount Va changes, the eccentricity output Vout apparently shows a high output for one period of the rotating shaft, as shown in f in FIG. 7, even though the eccentricity is constant. There was a problem that it was not possible to measure the amount of eccentricity stably.

This invention was made to solve the above-mentioned problems, and it is possible to cancel the DC offset change amount of the eccentricity human input signal with the eccentricity output signal, thereby eliminating the increase in the eccentricity command due to disturbance. The purpose is to obtain a circuit for measuring eccentricity of a rotating shaft.

[Means to solve the problem]

The eccentricity measurement circuit of a rotating shaft according to the present invention includes a sampling and holding circuit that reads and outputs a measured eccentricity output signal at regular sampling intervals, and a sampling and holding circuit that reads and outputs a measured eccentricity output signal at regular sampling intervals, and a sampling and holding circuit that reads and outputs a measured eccentricity output signal and outputs the measured eccentricity output signal from the sampling and hold circuit. and a low-level output selection circuit that selects and outputs one of the eccentricity output signals having a low level among the eccentricity output signals.

[Effect]

According to this invention, since there is a signal input time difference corresponding to the sampling time between each eccentricity output signal input to the low-level output selection circuit, even if the eccentricity output signal changes in a stepwise manner due to a DC offset. Also, since the change appears with a time difference in each eccentricity output signal,
An output signal having a lower level than either of the output signals can be selectively output, so that the eccentricity output signal becomes a signal output without an increase in indication due to disturbance.

(Example) Hereinafter, an example of the present invention will be explained with reference to the drawings.
The figure is an overall configuration diagram of a circuit for measuring eccentricity of a rotating shaft according to the fourth embodiment, and FIG. 2 is a time chart illustrating the operation of this embodiment. In each figure, the same reference numerals as in Figures 5 and 6 are the same.
or a corresponding portion thereof, and a detailed explanation of the operation thereof will be omitted.

In FIG. 1, (8c) is a sample hold signal generator that outputs a sample hold signal (Vr3) every time a protrusion protruding from the rotating shaft (6) is detected, and (13) is a sample hold signal generator (Vr3) that outputs a sample hold signal (Vr3). 3) Every time it is done manually,
Eccentricity output signal Vout output from the selection circuit (9)
sample hold circuit that reads and outputs (14)
is the eccentricity output signal Vou output from the selection circuit (9)
Sample and hold circuit (
13) is a low level selection circuit that selects and outputs an eccentricity output signal Vout-1 having a lower level than the eccentricity output signal Vsout outputted from the eccentricity output signal Vsout.

Next, the operation of this embodiment with the above configuration will be explained with reference to the time chart of FIG. Now, when measuring the eccentricity of the rotating shaft of a turbine generator, if the distance between the eccentricity detection sensor and the rotating shaft changes stepwise due to thermal expansion of the turbine, the change will be caused by the eccentricity as shown in a in Figure 2. Quantity human power signal Vin
As a result, the eccentricity input signal Vin
The DC level changes steadily in a stepwise manner. The eccentricity input signal Vin that has changed stepwise in this way is transmitted to the second and third peak hold circuits (4) and (5) at the time of change.
) is held as the peak value of the input signal (d, e in Figure 2). Then, the eccentricity output signal V of the selection circuit (9)
A DC offset change Va is superimposed on a normal high level signal (Vp-Vv) at out. This eccentricity output signal Vo
ut is read into the sample hold circuit (13) from time tsl to ts2 by the sampling pulse output from the sampling pulse generator (8C), and Vs
It is input to the low level selection circuit as out. The low level selection circuit (14) receives the eccentricity output signal Vo from the selection circuit (9) before the sampling time tsl to ts2.
Since ut is input, when the high level part of the eccentricity output signal Vout is manually input, the low level part of the sampled and held eccentricity output signal Vsout is input, or the high level part of the eccentricity output signal Vsout is input. At the time when the level portion is input, the eccentric amount output signal Vout becomes a low level. Therefore, the low level selection circuit (14) can always select and output the low level eccentricity output signal Vout-1 with the offset component canceled. The present invention is not limited to the above-mentioned embodiments, and the same effects can be obtained by using eccentricity measurement circuits shown in the following figures.

The eccentricity measuring circuit shown in Fig. 3 is a modification of the reset pulse generating circuit of the circuit shown in Fig. 1.
Reset pulse Vr of the reset pulse generator (8)
3 by a predetermined time using a delay circuit (15), and Vr2
1 and 2, except that Vrl is formed by forming Vrl by a predetermined time delay in a delay circuit (16).
It operates in the same way as described for the figure. FIG. 4 shows an eccentricity measurement circuit according to another modification. (2a) is a circuit that peak-holds the positive side of the input signal Vin, (4
a) is a circuit that peak-holds the negative side of the input signal, (3) is a comparison circuit that calculates the difference between the outputs of (2a) and (4a), (5a) is the first sample-and-hold circuit, (6)
is the rotating shaft, (7) is the protrusion, (8) is the reset pulse generator, (9a) is the second sample hold circuit, (14)
is a Low selector, and (lla) and (12a) are delay circuits. This circuit operates in the same manner as described in connection with FIGS. 1 and 2, except for the peak-to-peak amplitude detection circuit (1) and the reset pulse generation circuit (8). Further, in the above embodiment, the protrusion (7) of the rotating shaft (6) may be a groove instead of a protrusion, and the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, since the change in the DC offset amount of the human input signal of the eccentricity sensor to be measured is input as a disturbance, the circuit eliminates the disturbance so that this disturbance is not regarded as the eccentricity amount, and the eccentricity sensor has good stability. A quantity measuring circuit is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a circuit for measuring eccentricity of a rotating shaft according to an embodiment of the present invention, FIG. 2 is a time chart when a DC offset fluctuation of the eccentric input signal in FIG. 1 occurs, and FIG. 4 is a measuring circuit according to another embodiment of the present invention, FIG. 5 is a block diagram showing an example of a conventional eccentricity measuring circuit, FIG. 6 is an operation time chart of FIG. 5, and FIG. 7 is a block diagram showing an example of a conventional eccentricity measuring circuit. 1 shows a time chart when a DC offset fluctuation of an eccentric human input signal occurs in a conventional eccentricity measuring circuit. In the figure, (4) is the second peak hold circuit, (5
) is the third peak hold circuit, (6) is the rotation axis, (7
) is the protrusion, (8c) is the sampling pulse generator, (9
) is a signal selection circuit, (13) is a sample hold circuit,
(14) is a low level selection circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A first peak hold circuit having a protrusion protruding from the rotating shaft and holding the peak value of an electric signal indicating the eccentricity of the rotating shaft and outputting it as an eccentricity signal; and a second peak holding circuit holding the eccentricity signal. A rotating shaft eccentricity measurement circuit comprising: a peak hold circuit; and a signal selection circuit that selects and outputs a higher level output from the output of the first peak hold circuit and the output of the second peak hold circuit. a sampling pulse generator that generates a sampling pulse every time a protrusion on the rotating shaft is detected; a sampling hold circuit that samples and holds the output of the signal selection circuit using the sampling pulse; and an output of the sampling and hold circuit and the signal selection circuit. A circuit for measuring eccentricity of a rotating shaft, comprising: a low-level output selection circuit that selects and outputs one of the low-level outputs.