JPH07119596B2 - Rotation axis eccentricity measurement circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotating shaft eccentricity measuring circuit for measuring the amount of eccentricity of a rotating shaft of a turbine generator or the like.

[Conventional technology]

FIG. 5 shows an eccentricity amount measuring circuit disclosed in, for example, Japanese Patent Publication No. 56-48802. This eccentricity amount measuring circuit includes a peak-to-peak amplitude detecting circuit (1) with a protrusion (7) of a rotating shaft (6). Reset pulse signals Vr1 and Vr2 that are detected and synchronized with the rotation cycle
Reset pulse generators (8a) and (8
b) and a third peak hold circuit (5) for holding the peak value of the eccentricity amount signal V1 of the peak hold circuit (4)
And the eccentricity signal V1 and the third peak hold circuit (5)
Of the eccentricity signal V2 which is the output of the diode (10), (11), the resistor (1
And a signal selection circuit (9) consisting of 2), wherein the first and second peak hold circuits (2),
(4) is reset by the reset pulse signal Vr1 while the third peak hold circuit (5) holds the eccentricity amount signal of a certain measurement cycle, and the third peak hold circuit (5) is the second peak hold circuit (5). The peak hold circuit (4) is reset while the eccentricity amount signal of the next measurement cycle is generated.

6A to 6F are waveform charts of respective parts 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. Has been done. Reset pulse signals Vr1 and Vr2 as shown in b and c of FIG. 6 are generated in synchronism with the rotation cycle of the rotating shaft. First, as shown in e of FIG.
2 resets the third peak hold circuit (5) holding the signal V1, and this circuit (5) again outputs the signal V1.
After peak holding, the reset pulse signal Vr1 resets the first and second peak holding circuits (2) and (4) as shown in FIG. When the output V2 holding the signal V1 of the previous cycle is generated from the hold circuit (5), the peak-to-peak amplitude detection circuit (1) generates the eccentricity signal V1 of the next cycle. The signal selection circuit (9) is the signal V1
The signal V2 which is at the high level is selected from the signals V2 and V2 to generate the output Vout as shown in f of FIG. Below, input signal Vin
A similar operation is repeated as the peak-to-peak amplitude decreases, and the output Vout follows the decrease in the input signal with a delay of one cycle, and as a whole, it becomes as shown in f of FIG.

[Problems to be Solved by the Invention]

Since the conventional eccentricity amount measuring circuit is configured as described above, for example, when measuring the eccentricity amount of the turbine generator, the distance between the eccentricity amount detection sensor and the object to be measured (rotating shaft) is stepped due to thermal expansion of the turbine. Change to the offset amount V which is the DC component of the eccentric input signal Vin as shown in FIG.
a also changes in steps. And this offset amount V
With the change of a, the eccentricity output Vout shows a stable eccentricity because the apparent eccentricity shows a high output as shown in f of FIG. There was a problem that it could not be measured.

The present invention has been made to solve the above problems, and the DC offset change amount of the eccentricity input signal can be canceled by the eccentricity output signal to eliminate the instruction rise of the eccentricity amount due to disturbance. The purpose is to obtain a circuit for measuring the amount of eccentricity of a rotating shaft.

[Means for Solving the Problems]

An eccentricity amount measuring circuit for a rotating shaft according to the present invention comprises a sampling hold circuit for reading and outputting a measured eccentricity amount output signal at a constant sampling cycle, a measured eccentricity amount output signal and an output from the sampling hold circuit. And a low level output selection circuit for selectively outputting any one of the low level eccentricity output signals.

[Action]

According to the present invention, since there is a signal input time difference for each sampling time between the eccentricity output signals input to the low level output selection circuit, even if the eccentricity output signal changes stepwise due to the DC offset. However, since the change amount appears in each eccentricity output signal with a time lag, it is possible to selectively output an output signal at a lower level than either one of the output signals. The signal output does not rise.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 2 is an overall configuration diagram of the rotating shaft eccentricity amount measuring circuit according to the present embodiment, and FIG. 2 is a time chart for explaining the operation of the present embodiment. In each of the drawings, the same reference numerals as those in FIGS. 5 and 6 indicate the same or corresponding portions, and the detailed description of the operation will be omitted. In FIG. 1, (8c) is a sample and hold signal generator that outputs a sample and hold signal (Vr3) each time a protrusion provided on the rotary shaft (6) is detected, and (13) is a sample and hold signal (Vr3). Each time is input, the sample-hold circuit that reads and outputs the eccentricity output signal Vout output from the selection circuit (9), and (14) is the eccentricity output signal Vout output from the selection circuit (9) and the sampling This is a low-level selection circuit that selectively outputs the eccentricity amount output signal Vout-1 having a lower level than the eccentricity amount output signal Vsout output from the sample hold circuit (13).

Next, the operation of this embodiment having the above configuration will be described with reference to the time chart of FIG. Now, when measuring the eccentricity amount of the circuit axis of the turbine generator, if the distance between the eccentricity amount detection sensor and the rotating shaft changes stepwise due to thermal expansion of the turbine, the change is eccentric as shown in a of FIG. Quantity Input signal Vin D
The C offset changes, and the DC level of the eccentricity input signal Vin changes steadily in steps. The eccentricity amount input signal Vin thus changed stepwise is held at the second and third peak hold circuits (4) and (5) as the peak value of the input signal at the time of change (see FIG. 2). D, e).
Then, the DC offset change Va is superimposed on the normal high level signal (Vp-Vv) on the eccentricity output signal Vout of the selection circuit (9). This eccentricity output signal Vout is read into the sample hold circuit (13) from time ts1 to ts2 by the sampling pulse output from the sampling pulse generator (8c) and is input to the low level selection circuit as Vsout. Since the eccentricity output signal Vout is input to the low level selection circuit (14) before the sampling time ts1 to ts2 of the selection circuit (9), the high level portion of the eccentricity output signal Vout is input. Occasionally, the eccentricity output signal Vout becomes low level at the time when the low-level part of the eccentricity output signal Vsout sampled and held is input or the high-level part of the eccentricity output signal Vsout is input. 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 embodiment, and the same effect can be obtained by using the eccentricity measuring circuit shown in each of the following drawings.

The eccentricity amount measuring circuit of FIG. 3 is a modification of the reset pulse generating circuit of the circuit of FIG. 1 and detects a protrusion (7).
Reset pulse Vr3 of the reset pulse generator (8)
1 and 2 except that the delay circuit (15) delays the signal for a predetermined time to form Vr2 and the delay circuit (16) delays the signal for a predetermined time to form Vr1. Works the same as it did. FIG. 4 shows an eccentricity amount measuring circuit according to another modification. (2a) is a circuit for peak-holding the positive side of the input signal Vin, (4a) is a circuit for peak-holding the negative side of the input signal, and (3) is (2a)
(5a) is the first sample and hold circuit, (6) is the rotary shaft, (7) is the protrusion, (8) is the reset pulse generator, and (9a) is The second sample and hold circuit, (14) is the Low selector, (11
a) and (12a) are delay circuits. This circuit operates in the same manner as described with reference to 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 rotary shaft (6) is
A groove may be used instead of the protrusion, and the same effect as that of the above-described embodiment can be obtained.

〔The invention's effect〕

As described above, according to the present invention, since the change in the DC offset amount of the measured eccentricity sensor input signal is input as the disturbance, the disturbance is removed so that the disturbance is not regarded as the eccentricity. No quantity measurement circuit is available.

[Brief description of drawings]

FIG. 1 is a block diagram showing an eccentricity amount measuring circuit for a rotary shaft according to an embodiment of the present invention, FIG. 2 is a time chart when a DC offset fluctuation of an eccentricity input signal in FIG. 1 occurs, FIG. 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 amount measuring circuit, FIG. 6 is an operation time chart of FIG. 5, and FIG. 7 shows a time chart when a DC offset fluctuation of an eccentricity input signal occurs in a conventional eccentricity amount 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 a protrusion, (8c) is a sampling pulse generator,
(9) is a signal selection circuit, (13) is a sample hold circuit, and (14) is a low level selection circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first peak hold circuit which projects a projection on a rotary shaft and holds a peak value of an electric signal indicating the eccentricity of the rotary shaft and outputs it as an eccentricity signal.
A second peak hold circuit for holding the eccentricity amount signal, and a signal selection circuit for selectively outputting either the output of the first peak hold circuit or the output of the second peak hold circuit, whichever is at a higher level. In the eccentricity amount measuring circuit for the rotating shaft, a sampling pulse generator that generates a sampling pulse each time the protrusion on the rotating shaft is detected, a sampling hold circuit that samples and holds the output of the signal selection circuit by the sampling pulse, An eccentricity amount measuring circuit for a rotating shaft, comprising: a sampling and holding circuit output; and a low level output selecting circuit for selectively outputting any one of the signal selecting circuit outputs having a low level.