JPH0742687A - Reverse rotation prevention device for internal pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the wear of the cam to extend the service life and to easily measure the wear at the time of periodic inspection. [Structure] An ion plating film of TiN or TiC is formed on the contact surface of the cam 26 with the inner ring to a thickness of 3 to 7 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal pump which is attached to a reactor pressure vessel and forcibly circulates the reactor water inside the reactor pressure vessel, and more particularly to a lower portion of the internal pump. The invention relates to a reverse rotation preventing device for an internal pump, which is an improved reverse rotation preventing device.

[0002]

2. Description of the Related Art FIG. 4 (a) is a perspective view showing a state in which a plurality of internal pumps are attached to a reactor pressure vessel 1, and FIG. 4 (b) is a portion for showing the action of the internal pumps. FIG. 4 (c) is a detailed explanatory view of the vertical cross section of the internal pump.

As shown in FIGS. 4 (a), 4 (b) and 4 (c), the internal pumps 2 are vertically provided in the lower portion of the reactor pressure vessel 1 at equal intervals. As shown in FIG. 4 (b), the internal pump 2 sucks the reactor water from above by a main impeller described later with reference to FIG. As shown by the arrow 4 in Fig. 4, the core 5 is discharged by the suction and discharge.
The reactor water is allowed to flow upward inside the reactor to cool the reactor core 5.

The reason why a plurality of internal pumps 2 are provided is that even if one or two internal pumps fail, the remaining internal pumps cool the reactor core 5 sufficiently. To drive safely. However, if one of the internal pumps fails and the internal pump is stopped, the main impeller at the upper end of the internal pump is shown by the arrow 3 in FIG. 4B from above the failed internal pump. The internal pump reverses due to the inflowing reactor water as shown by. Then, the rotating shaft of this internal pump vibrates due to the journal bearing (radial bearing) for one-way rotation incorporated in this internal pump, which not only disturbs the flow of the reactor water but also decreases the power generation efficiency. To do. Therefore, inside each of the internal pumps 2, there is provided an operation preventing device which is a target of the present invention as described later in detail with reference to FIG.

In FIG. 4 (c), an internal pump 2 comprises a main impeller portion 6 at the upper end and a submersible motor incorporated in a case projecting downward from the reactor pressure vessel 1 below the main impeller portion 6. The part 7 and the reverse rotation preventing device 8 provided at the lower end of the submersible motor part 7 are generally configured.

Of these, the main impeller portion 6 at the upper end protrudes upward from the axial center of the submersible motor portion 7 and is attached to the inside of the reactor pressure vessel 1 of the pump shaft 9;
The main impeller 10 is coaxially fitted with guide vanes 11 which are loosely fitted to the outside of the main impeller 10 and fixed at the outer periphery of the upper end and the inner periphery of the lower end to the reactor pressure vessel 1.

On the other hand, the submersible motor unit 7 is completely separated from the reactor water inside the reactor pressure vessel 1 by the purge water 12 supplied from the outside as shown by the broken line. The submersible motor unit 7 is attached to the lower end of the pump shaft 9 described above with reference to FIG.
In (c), a tubular motor shaft 13 integrated with the pump shaft 9 press-fitted from below, a rotor 14 inserted and fixed to the outer periphery of this motor shaft 13, and an inner periphery of a motor casing 15 are attached. The cylindrical stator 16 and the auxiliary impeller 17 for circulating the cooling water, which is integrally formed at the lower end of the motor shaft 13, are substantially configured.

Of these, the upper end of the motor shaft 13 bears the radial load of the upper end by an upper radial bearing 18 inserted into the inner periphery of the small diameter portion of the upper end of the motor casing 15, and the lower end of the motor shaft 13 is Similarly, by the lower radial bearing 19 inserted in the inner periphery of the small diameter portion of the lower portion of the motor casing 15,
The lower radial load is supported.

Further, an upper thrust bearing 20 is provided on an upper surface of the auxiliary impeller 17, and a lower thrust bearing is provided on an upper surface of a lower cover 23 provided at a lower end of the motor casing 15 at a lower portion of an outer peripheral lower end of the auxiliary impeller 17. 21 is placed and supports the thrust load of the pump shaft 9 and the motor shaft 13.

Further, the reverse rotation preventing device 8 is shown in FIG. 5 showing a partially enlarged view of FIG. 4 (c) and a sectional view taken along the line BB of FIG. 5 (however, the space is shown with a 90 ° angle changed). As shown in FIG. 6, an annular outer ring 22 fixed to the lower end of the auxiliary impeller 17, and a lower cover 23 provided at the center of the outer ring 22.
An inner ring 24 having a U-shaped cross section, which is fixed to the upper end of a cap 23a that is inserted into the center of the outer ring 22, and annular retainer rings 25A and 25B that are loosely fitted to face each other above and below the inner circumference of the outer ring 22.
And a plurality of cams 26, which are provided at equal intervals between the retainer rings 25A and 25B and protrude upward and downward, penetrate the upper and lower retainer rings 25A and 25B, and the outer ring 22 of these cams 26. It is composed of a pair of coil springs 33 wound on the outer sides of the stepped portions formed on the upper and lower sides on the opposite sides.

Of these, the cam 26 has a prism shape with a substantially rhombic cross section, and the surface facing the outer ring 22 and the inner ring 24 is formed in an arc shape, and the material is made of martens in consideration of corrosion resistance and wear resistance. Site-based stainless steel (SUS431) is used and heat treated to the highest hardness (HrC30) that does not cause stress corrosion cracking. The inner ring 24 is made of the same material and is similarly heat-treated.

In the reverse rotation preventing device 8 thus constructed, the pair of coil springs is in operation while the internal pump is stopped.
The cam 26 is pressed against the outer circumference of the inner ring 24 by a force of about 1 kgf by 33. However, as the internal pump is activated and accelerated, centrifugal force applied to the cam 26 and the coil spring 33 causes the moment of Fc to work outward with the upper and lower shafts as fulcrums, as shown in FIG. When pm is exceeded, the pressing force Fs by the coil spring 33 is exceeded, and each cam 26 swings with the shaft protruding vertically in the clockwise direction as a fulcrum. Then, the inner ring 24 side of each cam 26 is separated from the outer peripheral surface of the inner ring 24 by a gap s as shown in FIG. 7, and approaches the rotational speed of the internal pump by the frictional force between the cam 26 and the outer ring 22.

On the contrary, from the state of FIG. 7, as the internal pump is stopped, the rotation speed of this internal pump is reduced to 3
When it becomes less than 00 rpm, the pressing force Fs of the coil spring 33 becomes larger than the moment Fc due to the centrifugal force, and a part of the arcuate surface of each cam 26 on the inner ring 24 side becomes a part of the inner ring 24 as shown in FIG.
Is pressed to the outer periphery of. As a result, the cam can be started and stopped once
The distance that the inner ring 24 side of 26 slides on the outer periphery of the inner ring 24 is about 8 m. The reverse rotation preventing action is the same as that generally marketed as a one-way clutch.

On the other hand, the submersible motor unit 7 for driving the internal pump 2 is cooled with pure water completely separated from the reactor water as described above, as described below. That is, in FIG. 4C, the rotation of the pump shaft 9 causes the auxiliary impeller 17 to rotate.
When the rotor rotates, the cooling water sucked into the auxiliary impeller suction port 31 at the lower part of the auxiliary impeller 17 is discharged from a pump hole 17a formed in the auxiliary impeller 17 as shown in FIG. , Rises between the rotor 14 and the stator 15 via the lower radial bearing 19, cools them, and flows into the motor upper chamber 27 via the upper radial bearing 18. Then, this cooling water flows into the heat exchanger 29 through the pipe 28 shown by the broken line, and after being cooled by this heat exchanger 29,
Similarly, the auxiliary impeller suction port 31 is passed through the pipe 30 indicated by the broken line 30.
Return to. After that, the rotor 14 and the stator 15 of the submersible motor unit 7 are cooled by circulating in the same manner.

[0015]

However, in the reverse rotation preventing device for the internal pump constructed as described above, the cam 26 slides in a state of being in contact with the outer circumference of the inner ring 24 until a predetermined rotation speed is reached. Since it rotates while rotating, the sliding surfaces of the cam 26 and the inner ring 24 wear when the number of starts increases. In particular, since the present reverse rotation preventing device is used in water, the amount of wear increases as compared with the use in normal oil. Then, the wedge action by the cam 26 having a substantially rhombic cross section, that is,
The reverse rotation prevention function of the internal pump is impaired.

[0016] Therefore, the cam 26 is inspected for abnormalities during the regular inspection every five years.
As described above, the shape is a rhombus and the arcuate portion is formed, and in the measurement with a caliper or a micrometer, the measured value varies depending on the position of the arcuate portion, so that the wear inspection may not be accurately performed. Then, not only a special measuring instrument such as a three-dimensional measuring instrument is required, but even if this three-dimensional measuring instrument is used for measurement, the number of cams per unit is large, and each cam is a measuring instrument. Since it takes a lot of setup time to mount the device, it takes a long time to perform the measurement, and it may not be possible to complete the inspection within the predetermined inspection period.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reverse rotation preventing device for an internal pump, which can reduce wear of the cam, prolong its life, and can be inspected accurately in a short time.

[0018]

According to a first aspect of the present invention, there is provided an internal pump in which a plurality of cams are loosely fitted between an outer ring rotating with a rotary shaft and an inner ring provided inside the outer ring. In the reverse rotation preventing device, an ion plating film is formed on at least a contact surface of the cam with the inner ring.

[0019]

The ion plating film is dense and has a high hardness, so that the wear resistance of the cam can be dramatically improved.

It has been experimentally found that the adhesion of the coating is high when the thickness of the coating is about 3 to 7 μm.

On the other hand, when the wear of the conventional cam is measured, it is necessary to measure the wear thickness of about 10 to 30 μm, but since the coating of the ion plating is greatly different from the color of the background of the metal, it depends on the wear. By measuring the width of the exposed substrate, the amount of wear can be easily and accurately estimated, and the replacement timing of the reverse rotation prevention device can be determined in a short time.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reverse rotation preventing device for an internal pump according to the present invention will be described below with reference to the drawings. Figure 1
It is a figure which shows the principal part of this invention, and is a figure corresponding to FIG. 6 shown by the prior art.

In the reverse rotation preventing device for the internal pump according to the present invention, as shown in FIG.
Thickness 3 by ion plating of iN or TiC
A coating of ˜7 μm (average thickness 5 μm) is formed. In addition,
It may also be applied to the outer surface of the inner ring.

In this case, the cam 26 may be applied only to the sliding surface with the inner ring 24. However, since masking is required, the inventor has made the entire surface including the inner ring without masking. Conventional stainless steel (SU
A comparative test was carried out with a cam made of only material (S431).

FIG. 3 is a graph showing the test results. In this test, one cam was attached to the outside of the inner ring with a pressing force of 1 kgf (constant), and the inner ring was rotated. The test was performed in water similar to the actual machine, and other test conditions are as shown in the graph.

As shown in FIG. 3, in the conventional combination of cam and inner ring, the first time was 518 mg, the second time was 434 mg, and the third time was 381 mg, whereas TiN or TiC ion plating was performed. When the cam coating is TiN and the inner ring is TiC, the minimum is 0.01 mg to 0.02 mg. When the cam coating is TiC and the inner ring is TiN, the maximum is 0.08 mg. It was up to 0.11 mg.

Although the wear amount of the inner ring was not measured,
In the cam, the wear portion is determined by the portion that slides on the inner ring, while the contact portion on the inner ring side is constantly changing, so the thickness of wear is small.

In the reverse rotation preventing device for the internal pump thus constructed, the thickness of the coating film of the cam is accurately recorded in advance before being incorporated, so that an enlarged view as seen from the arrow A in FIG. 1 is shown. 2 (a) and this FIG. 2 (a)
As shown in Fig. 2 (b) showing the cross section of the cam, the thickness (W) of the worn part of the cam can be easily measured by measuring the width (W) of the background (SUS431) that is different from the color of the film that appears due to the wear of the film. Can be measured.

[0029]

[Table 1]

Table 1 shows the width of the background (W) calculated from the curvature of the contact portion with the inner ring of the cam and the wear amount (h) of the background of the cam.
(Degree of reduction in the radial direction) is shown. This value is when the thickness of the coating film of the cam is 5 μm. Moreover, although the story goes back and forth, the allowable value of the wear amount of the cam is designed to be 50 μm when the wear of the inner ring is zero. The test condition of 3 km shown in Fig. 3 corresponds to the sliding distance when the internal pump was started and stopped 375 times.

Therefore, in the reverse rotation preventing device for the internal pump thus constructed, the periodic inspection (5
(Every year), the remaining life can be easily known by visually observing or measuring the wear width W of the cam shown in FIG. 2 with a caliper or a ruler. In addition, as shown in the test results in FIG. 3, in reality, with the number of startups of the conventional internal pump, it is not necessary to replace the reactor for 40 years, which is considered to be the life of the reactor. Even when the number of starts increases and the wear of the cam increases under some conditions including the previous test, it is possible to predict the time for replacement.

In the above embodiment, the case where TiN or TiC is used as the ion plating film has been explained.
An ion plating film of iC, Al ₂ O ₃ or PaC may be formed.

Further, in the above-mentioned embodiment, the film is formed on both the cam and the inner ring, but the inner ring side may be omitted, and the film thickness is 5 μm on average. However, it may be thinner or thicker.

[0034]

As described above, according to the invention of claim 1,
In a reverse rotation preventing device for an internal pump, in which a plurality of cams are loosely fitted between an outer ring that rotates with a rotating shaft and an inner ring provided inside the outer ring, an ion plating is performed on at least the contact surface of the cam with the inner ring. By forming a film, the wear resistance of the contact surface with the inner ring of the cam was improved and the progress of wear during the periodic inspection was easily measured, so the service life was extended and the inspection was performed easily in a short time. It is possible to obtain a reverse rotation preventing device for an internal pump that can be used.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an embodiment of a reverse rotation preventing device for an internal pump according to the present invention.

FIG. 2 (a) is an enlarged view of FIG. (B) is
FIG.

FIG. 3 is a graph showing the operation of the reverse rotation preventing device for an internal pump according to the present invention.

FIG. 4A is a perspective view showing a state in which a conventional internal pump is attached to a reactor pressure vessel. (B)
[Fig. 4] is a partially broken explanatory view showing a flow of cooling water in a reactor pressure vessel by a conventional internal pump. FIG. 6C is an enlarged detailed view of a vertical cross section of a conventional internal pump.

FIG. 5 is a vertical cross-sectional view showing a reverse rotation prevention device attached to a conventional internal pump.

6 is a sectional view taken along line BB of FIG.

FIG. 7 is a partial cross-sectional view showing the operation of a conventional reverse rotation preventing device for an internal pump.

FIG. 8 is a partial cross-sectional view showing the operation of the conventional reverse rotation preventing device for an internal pump, which is different from that in FIG. 7.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Internal pump, 5 ... Reactor core, 6 ... Main impeller part, 7 ... Submersible motor part, 8 ... Reverse rotation prevention device, 17 ... Auxiliary impeller, 22 ... Outer ring, 24 ... Inner ring, 25
A, 25B ... Retainer ring, 26 ... Cam, W ... Width of background.

Claims (1)

[Claims] 1. In a reverse rotation preventing device for an internal pump, wherein a plurality of cams are loosely fitted between an outer ring that rotates with a rotating shaft and an inner ring that is provided inside the outer ring. A reverse rotation preventing device for an internal pump, characterized in that an ion plating film is formed on the contact surface.