JPH1183470A - Contact type clearance measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make detectable the expansion of a rotary body in the diameter direction at high precision, by rotating the rotary body at a high rotation speed, bringing the rotary body into contact with the tips of a plurality of thermocouples with different projected lengths, by the centrifugal force, and detecting the thermocouple, with which the rotary body is brought into contact, based on the output signal of the thermocouple. SOLUTION: The difference of the projected length between the most projected thermocouple 1 of three thermocouples 1 and the second projected one and that between the second projected one and the least projected one are set, for example, about 0.3 mm, respectively. A moving blade 25 is extended when a steam turbine is started and rotated at high rotation speed by the centrifugal force and the distance between the initially set moving blade 25 and the thermocouples 1 is narrowed and the moving blade 25 is at last brought into contact with the most projected thermocouple 1 and due to the friction heat, the thermocouple 1 transmits characteristic output waveforms. When the moving blade 25 is further extended to reach the second most projected thermocouple 1, the thermocouple 1 transmits characteristic output waveforms in the same manner. The period from the first time to the second time is measured and the degree of the expansion of the moving blade 25 can be calculated by adding the distance between those thermocouples 1 to the initially set distance. Without being affected by electromagnetic induction, temperature or the like, precise and reliable measurement can be carried out by the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact-type clearance measuring device applied to measurement of the extension of a moving blade of a steam turbine or a gas turbine.

[0002]

2. Description of the Related Art In conventional displacement measurement of a rotating body, a displacement meter using electromagnetic induction, ultrasonic waves, laser light, or the like has been generally used.

When measuring the amount of extension of the moving blade of a steam turbine during high-speed rotation, an eddy current type displacement meter 27 shown in FIG. 4 is often used. Of the casing 21 slightly away from the rotor blade 25
And measured the extension of the tip of the bucket 25.

[0004] The steam turbine is provided with about 100 blades 25 in one stage, and when it rotates at a high speed, it passes the displacement meter 27 more than 6000 times per second.

[0005]

In measuring the extension of the moving blade of a conventional steam turbine, an eddy current type displacement meter is often used as described above. There were the following issues.

That is, since the tip shape of the moving blade is complicated and small, the output waveform of the displacement meter is disturbed, or the amount of extension of the moving blade measured by the displacement meter due to ambient temperature, vibration, etc. is not stable. In some cases, it was not possible to measure accurately. The present invention seeks to solve the above problems.

[0007]

According to the present invention, there is provided a contact-type clearance measuring device, comprising: a tubular sensor case disposed through a seat inside a casing of a rotary machine; A plurality of sensor probes that can move in the direction of the central axis of the body, and that are fixed in the sensor probe with a certain difference in the projecting lengths of the tips that penetrate through the probe and face the rotating body. A thermocouple, a probe moving means disposed outside the casing of the seat to move the sensor probe in the direction of the central axis of the rotating body, and a probe movement provided in the moving means for measuring a moving amount of the sensor probe It is characterized by having a quantity measuring means.

When measuring the amount of diametrical extension of a rotating body due to centrifugal force using the contact-type clearance measuring device according to the present invention, the probe moving means and the probe moving amount measuring means must first measure the sensor probe. The position is adjusted, and the distance between the tip of the most protruding thermocouple and the rotating body is set as a predetermined initial set distance.

Next, in this state, the rotating machine is started to rotate the rotating body to a predetermined high-speed rotation. When the rotating body rotates at high speed, its diameter increases due to centrifugal force,
Touch the end of the thermocouple.

Since the thermocouple whose tip is in contact with the rotating body detects and outputs a temperature rise due to frictional heat with the rotating body, the thermocouple in contact with the rotating body can be detected based on an output signal of the thermocouple. The extension amount of the rotating body is detected by adding the initial setting value to the distance between the tip of the most protruding thermocouple and the tip of the thermocouple having the shortest protruding length in contact with the rotating body. be able to.

In the present invention, the measurement is performed by bringing the rotating blade into contact with a thermocouple arranged with the tip shifted, so that the thermocouple is not affected by electromagnetic induction, ambient temperature, etc. unlike the conventional apparatus. In addition, it is possible to accurately and reliably measure the amount of diametrical extension of the rotating body.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A contact type clearance measuring apparatus according to an embodiment of the present invention will be described with reference to FIG. Note that the present embodiment is a case where the present embodiment is applied to the measurement of the amount of extension of a steam turbine blade.

In FIG. 1, reference numeral 6 denotes a seat attached to a casing 21 of a steam turbine. A lower part of the seat 6 is connected to a tubular sensor case 3 and an upper part is provided with a bearing 8 provided therein. Case 7 is connected.

Reference numeral 2 denotes a sensor probe which penetrates the sensor case 3 and the bearing case 7 up and down. A stopper 20 and a scale 14 are provided on an upper side surface, and a set screwed to the bearing case 7 on a center side surface. An O-ring 11 is provided for sealing between the key groove 9 in which the bolt 10 is set and the bearing case 7.

Reference numeral 4 denotes a tubular rotary shaft having a lower outer periphery joined to the inside of the bearing 8 in the bearing case 7;
On the lower inner surface, there is provided a female screw to be screwed with the moving screw 5 provided on the side surface of the sensor probe 2.

A disk-shaped scale plate 1 having a scale 15 provided on a side surface of a center portion of the rotating shaft 4 opposite to a pointer 19 provided on an upper side surface of the bearing case 7 is provided.
The grip lever 1 is provided on the scale plate 13.
6 are provided, and a screw 12 on which a set nut 17 and a lock nut 18 are screwed is provided on the upper side surface.

Reference numeral 1 denotes three thermocouples vertically penetrating the sensor probe 2, the lower end of which faces the tip of the steam turbine rotor blade 25, and the upper end thereof has a thermometer 22 and a processing unit 23.
Is connected to the recorder 24 via the. The three thermocouples 1 are arranged with their tips shifted as shown in FIG. 2, and are located between the most protruding thermocouple 1a and the middle thermocouple 1b, and between the most protruding thermocouple 1b and the middle thermocouple 1b. The difference between the protruding lengths of the least protruding thermocouples 1c is 0.5 mm.

The sensor probe 2 is inserted into and pulled out of the casing 21 by the rotating shaft 4, the moving screw 5, the bearing case 7, the bearing 8, the keyway 9, the set bolt 10, the scale plate 13 and the grip lever 16. And a probe moving means for the scales 14, 1
A probe moving amount measuring unit for measuring the moving amount of the sensor probe 2 is formed by the pointer 5 and the pointer 19.

Next, the procedure for measuring the extension of the steam turbine blade using the contact-type clearance measuring device according to the present embodiment will be described below with reference to FIGS.

When performing the above measurement, the following operation is performed before starting the steam turbine to perform initial setting.
That is, the user operates the grip lever 16 to rotate the rotary shaft 4, lowers the sensor probe 2 until the tip of the thermocouple 1 a contacts the blade 25, and the scale 14 and the scale plate 13 of the sensor probe 2 when stopped. Thermocouple 1 from scale 15
The exact position of the tip of a is determined.

Subsequently, by operating the grip lever 16 while reading the scales 14 and 15, the rotating shaft 4 is reversed to raise the sensor probe 2, and the thermocouple 1 a
Is located at a position separated from the tip of the rotor blade 25 by a predetermined initial setting distance L.

In this state, the position is set by the set nut 17 and locked by the lock nut 18, and then the rotation shaft 4 is fixed by the stopper 20 so as not to rotate. Since the sensor probe 2 is provided with the key groove 9 and the set bolt 10, even if the rotating shaft 4 is rotated, the sensor probe 2 does not rotate but moves only in the vertical direction.

After completing the above initial setting, the steam turbine is started and the rotation is increased. When the steam turbine enters a high-speed rotation state, the moving blade 25 extends by centrifugal force, the distance between the initially set moving blade 25 and the thermocouple 1a decreases, and as shown in FIG. The thermocouple 1a comes into contact with the tip of the pair 1a and outputs an output waveform a shown in the lower part of FIG. When the rotor blade 25 further extends and reaches the thermocouple 1b, the thermocouple 1b outputs an output waveform b.

Therefore, the time required for the moving blade 25 to reach the thermocouples 1a and 1b can be obtained by measurement, and the extension amount of the moving blade 25 is set to the initially set distance L and the distance (0) between the thermocouples 1a and 1b. .5 mm). In the case shown in FIG. 3, the output waveform c does not change because the extension of the moving blade 25 does not reach the thermocouple 1c.

In the present embodiment, an example of application to a steam turbine has been described. However, the present invention can also be applied to measurement of the extension of a rotating body of general industrial equipment. Also, the initial set distance L, the number of thermocouples 1 and the amount of shift (length) of the tip
Is determined by the type of rotating machine.

[0026]

According to the present invention, there is provided a contact-type clearance measuring device, comprising: a tubular sensor case provided inside a casing of a rotary machine; A movable sensor probe, a plurality of thermocouples fixed to the inside of the probe with a certain difference between the protruding lengths of the tips protruding from the probe and facing the rotating body, and With the provision of the probe moving means provided and the probe moving amount measuring means provided in the moving means, the rotating blade is brought into contact with the thermocouple arranged with the tip shifted to measure. Therefore, unlike the conventional apparatus, the amount of diametrical extension of the rotating body can be accurately and reliably measured without being affected by electromagnetic induction, ambient temperature, and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a contact-type clearance measuring device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a positional relationship between a thermocouple and a rotor blade according to the embodiment.

FIG. 3 is an explanatory diagram of an operation of the thermocouple according to the embodiment.

FIG. 4 is an explanatory view of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermocouple 2 Sensor probe 3 Sensor case 4 Rotating shaft 5 Moving screw 6 Seat 7 Bearing case 8 Bearing 9 Keyway 10 Set bolt 11 O ring 12 Screw 13 Scale plate 14, 15 Scale 16 Grip lever 17 Set nut 18 Lock nut 19 pointer 20 stopper 21 casing 25 rotor blade

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01K 7/02 G01K 7/02 Z (72) Inventor Yukihiro Otani 2-1-1, Araimachi, Araimachi, Takasago-shi, Hyogo Pref.

Claims (1)

[Claims] 1. A tubular sensor case disposed inside a casing of a rotary machine via a seat, a sensor probe penetrating through the case and movable toward a central axis of a rotating body of the rotary machine. A plurality of thermocouples that penetrate the probe and that are fixed in the sensor probe with a certain difference between the projecting lengths of the tips facing the rotating body,
A probe moving means disposed outside the casing of the seat to move the sensor probe toward the center axis direction of the rotating body; and a probe moving amount measuring means provided in the moving means for measuring a moving amount of the sensor probe. A contact-type clearance measuring device comprising: