JP5470085B2 - Pad type thrust bearing, submerged motor, and vertical submerged motor pump - Google Patents

Description

  The present invention relates to a pad-type thrust bearing used in a rotating machine, and more particularly to a pad-type thrust bearing with reduced torque at the time of starting, a submerged motor equipped with the pad-type thrust bearing, and a vertical submersible The present invention relates to a motor pump.

  The pad type thrust bearing has a structure in which an axial thrust load acting on a rotating shaft is supported by a plurality of bearing pads arranged on a stationary surface via a disk-shaped bearing disk. In order to increase the load capacity, the bearing pad is supported from the stationary side with a swingable structure represented by the Kingsbury type (tilting pad type).

  FIG. 1 is a diagram showing a cross-sectional structure of a conventional pad-type bearing. The bearing load is supported by the dynamic pressure action generated between the bearing disk 5 and the upper bearing pad 2 and the lower bearing pad 3 constituting the bearing pad 4 by the rotation of the bearing disk 5 provided on the rotating shaft (main shaft) 6. The Usually, the bearing pad 4 is composed of an upper bearing pad 2 provided on the upper side of the bearing disk 5 and a lower bearing pad 3 provided on the lower side so as to support thrust loads in both the upper and lower directions. Each of the upper bearing pad 2 and the lower bearing pad 3 is composed of a plurality of bearing pads, and is housed in a bearing cover 1 including a disk 5, a bearing upper cover 1a, and a bearing lower cover 1b, and is integrated. Reference numeral 10 denotes a bearing housing.

  When the rotating shaft 6 rotates and the bearing disk 5 rotates, the swingable upper bearing pad 2 and lower bearing pad 3 are slightly tilted, and a lubricating liquid film is formed in the gap with the disk 5 due to the dynamic pressure effect. The disk 5, the upper bearing pad 2, and the lower bearing pad 3 can support a large load in a fluid lubricated state without solid contact.

  When the rotating machine is stationary and the rotating shaft is not rotating, the dynamic pressure effect does not occur and no lubricating liquid film is formed between the disk 5 and the bearing pad 4. When the lubricating liquid is oil having a relatively high viscosity, the oil remains on slight uneven portions present on the surfaces of the bearing disk 5, the upper bearing pad 2, and the lower bearing pad 3. At this time, if the load acting on the surfaces of the upper and lower bearing pads 2, 3 is low, the bearing may be able to start with boundary friction lubrication without causing galling. However, if the load acting on the surfaces of the upper and lower bearing pads 2 and 3 is not small, solid friction lubrication is likely to cause galling. In particular, when a lubricating liquid having a very low boundary lubrication effect such as water having a low viscosity is used, solid friction lubrication tends to occur at the start, and galling easily occurs.

  Since the self-weight of the rotating body acts on the thrust bearing of the vertical rotating machine, a boundary friction lubrication or solid friction lubrication state having a large friction coefficient occurs at the start. For this reason, compared with the time of steady operation of the rotary machine used as fluid lubrication, the torque of 10 to 100 times is needed at the time of starting.

  In order to reduce the starting torque acting on the thrust bearing of such a vertical rotary machine, a lift pump 8 that pressurizes and injects a lubricating liquid from the outside may be provided to the bearing pad 4 as shown in FIG. In the example shown in FIG. 2, the lift pump 8 pressurizes the lubricating liquid in the liquid storage tank 9 and injects it into a small hole provided in the lower bearing pad 3. Moreover, in the form described in Patent Documents 1 and 2, the lubricating liquid is guided from the inside of the bearing housing to the lift pump suction section through a pipe, and the lubricating liquid pressurized by the lift pump passes through a flexible tube or the like to the upper and lower bearings. It is guided to the pad part and is press-fitted into the bearing gap part (gap between the disk and the bearing pad) through a small hole provided in the center of the bearing pad.

The pressure of the lubricating liquid is adjusted so that the bearing disk 5 floats from the lower bearing pad 3. Lubricating liquid flow rate Q, pressure ΔP (bearing pad inlet pressure P ₁ -outlet pressure P ₂ ), bearing gap h, lubricating fluid viscosity coefficient μ, radius r ₂ when pad is approximately circular, central small hole If r ₁ is r ₁ , there is approximately the following relationship (Mechanical Engineering Handbook).
Q = π · h ³ · ΔP / {6 · μlog _e (r ₂ / r ₁ )}
Therefore, the pressure reaction force Wp acting on the bearing pad is
^{_{Wp = ∫ r2 r1 {P 1}} -Q / (πh 3 / 6μlog e (r / r 1))} · 2πr · dr
When the load Wg acting on the rotator becomes equal to the pad portion pressure reaction force Wp, the rotator floats and the starting becomes easy. Since fluid lubrication can be realized after the rotating body is started and dynamic pressure is generated in the bearing portion, it is not necessary to press-fit the lubricant from the lift pump.

  When the pressure Ph in the bearing housing 10 at the time of starting is high, when an externally installed lift pump 8 as shown in FIG. 2 is used, the discharge pressure becomes Pp = ΔP + Ph. In the case of Ph> ΔP, most of the discharge pressure of the lift pump 8 is consumed to withstand the pressure in the bearing housing 10 and is used only slightly for bearing levitation. In this case, since the discharge pressure of the lift pump 8 becomes larger than the pressure ΔP for bearing levitation, the bearing disk 5 is pressed against the upper bearing pad 2 when the discharge pressure is slightly exceeded. Therefore, the pressure control of the lift pump 8 must be strictly performed.

  In addition, when the pressure Ph in the bearing housing 10 at the time of starting is high, the pressure piping connecting the lift pump 8 and the bearing housing 10 must be designed to withstand high pressure, and vibration, pressure change, temperature of the rotating machine body The possibility of internal liquid leaking from the pipe joint due to changes or the like increases. In particular, when the rotary machine main body is a non-leakable vertical sealless motor pump, the non-leakage of the lift pump 8 and the pressure piping must be ensured.

Japanese Patent Application Laid-Open No. 60-065908 Japanese Patent Application Laid-Open No. 07-027140

  However, in the prior art, there is a requirement that the pressure control of the lift pump 8 must be strictly performed when the pressure Ph in the bearing housing 10 at the time of starting is high, and a pressure pipe connecting the lift pump 8 and the bearing housing 10 part. The high pressure resistance and non-leakage, especially when the rotary machine main body is a non-leakable vertical sealless motor pump, does not sufficiently satisfy the non-leakage of the lift pump 8 and pressure piping.

  The present invention has been made in view of the above points, and has a structure that is easy to prevent leakage of lubricating liquid, and uses a pad type thrust bearing provided with a lift pump for reducing starting torque, and using the pad type thrust bearing. An object is to provide a submerged motor and a vertical submerged motor pump.

In order to solve the above-described problems, the present invention provides a pad type thrust bearing including a lift pump that pressurizes and supplies a lubricating liquid to the pad surface. The lift pump includes an impeller of the lift pump and a thrust bearing. Rutotomoni provided in the bearing housing, a part of the motor of the motor housing which drives the lift pump is characterized in that it is coupled in a state of being inserted into the bearing housing.

  According to the present invention, in the pad type thrust bearing, the lift pump is a sealless motor pump.

  Further, the present invention is characterized in that in the above-described pad type thrust bearing, the sealless type lift pump is structured so as to be integrally removable from the outside of the bearing housing.

  Further, the present invention is a pad type thrust bearing provided with a lift pump that pressurizes and supplies a lubricating liquid to the pad surface, and the motor housing of the sealless motor pump constituting the lift pump is different from the bearing housing of the thrust bearing. It is characterized by being coupled to a thrust bearing so as to form a sealing surface for the lubricating liquid therebetween.

  According to another aspect of the present invention, there is provided a vertical submersible motor including the pad type thrust bearing.

  The present invention also provides a vertical submersible motor pump comprising the vertical submersible motor.

  In the present invention, since the impeller of the lift pump is provided in the bearing housing of the thrust bearing, it is easy to prevent leakage of the lubricating liquid even when the lubricating liquid becomes high pressure.

It is a figure which shows the cross-sectional structure of the conventional tilting pad type | mold thrust bearing. It is a figure which shows the cross-section of the tilting pad type | mold thrust bearing provided with the conventional external lift pump. It is a figure which shows the planar structure of the bearing pad which has a liquid injection hole. It is a figure which shows the cross-sectional structure of the tilting pad type | mold thrust bearing which has a built-in type lift pump based on this invention. It is a figure which shows the cross-section of the vertical submersible motor hump using the tilting pad type | mold thrust bearing which has a built-in type lift pump based on this invention. It is a figure which shows the cross-section of a universal joint.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 4 is a view showing a cross-sectional structure of a pad-type thrust bearing according to the present invention. This pad type thrust bearing has a built-in sealless motor (candle motor in which the stator core and windings are covered with a can) type lift pump, and is integrated with the bearing housing 10.

  An upper bearing pad 2 and a lower bearing pad 3 are installed in a bearing cover 1 including a bearing upper cover 1a and a bearing lower cover 1b so as to sandwich a bearing disk 5 fixed to a rotating shaft (main shaft) 6 of a rotary machine. . The upper bearing pad 2 is composed of a plurality of bearing pads, each of which is supported on the bearing upper cover 1 a via a tilt mechanism 7. Similarly, the lower bearing pad 3 is composed of a plurality of bearing pads, each of which is supported on the bearing lower cover 1b via a tilt mechanism 7.

  FIG. 3 is a top view of the lower bearing pad 3 as viewed from above. As shown in the drawing, the lower bearing pad 3 has a plurality (eight in the figure) of bearing pads 11 arranged circumferentially on the bearing lower cover 1 b, and a bearing lift is provided at the center of each bearing pad 11. A hydraulic pressure outflow hole 11a through which the lubricating oil flows out is opened. Further, a hydraulic pressure introducing hole 11b for introducing a bearing lift lubricant is opened on the lower surface of each bearing pad 11.

  The bearing upper cover 1a has a substantially cylindrical shape, and has an upper wall 1c formed with a through hole 1e through which the main shaft 6 passes in the upper center. A tilt mechanism 7 for supporting each bearing pad 11 is provided on the lower surface of the upper wall 1c. A side wall 1d extends downward from the periphery of the upper wall 1c and is coupled to the bearing lower cover 1b. A plurality of holes 1f are provided in the side wall 1d.

  Further, a through hole 1g penetrating the bearing lower cover 1b is provided at a position corresponding to the hydraulic pressure introducing hole 11b of the bearing pad 11 of the lower bearing pad 3. A lubricating liquid flow path cover 17 is attached to the lower surface of the bearing lower cover 1b. A hole 17a into which the lift pump 12 is inserted is provided at the center of the lubricating liquid flow path cover 17, and a disc-shaped lubricating liquid flow path 18 is formed between the lower surface of the bearing lower cover 1b. The lubricating fluid flow path cover 17 is coupled to the bearing housing 10 by legs 19. Since the load on the thrust bearing is supported by the bearing housing 10 via the legs 19, it may be reinforced by separately providing legs that couple the bearing cover 1 and the bearing housing 10.

  The lift pump 12 includes a motor unit M and a pump unit P. The motor unit M includes a canned motor 12c, and the lift pump 12 is configured as a sealless motor pump. A centrifugal impeller 12a is fixed to the upper end of the rotary shaft 20 of the lift pump 12 so that the suction side is downward. Between the impeller 12a and the canned motor 12c, a pump casing 21 including an upper pump casing member 21a and a lower pump casing member 21b in which a lubricating liquid suction passage is formed is fixed to the motor housing 22. The pump casing 21 is inserted into a hole 17 a in the center of the lubricating liquid flow path cover 17, and an upper pump casing member 21 a that closes the hole 17 a and a lower pump casing member 21 b that is fixed to the motor housing 22 suck in the lubricating liquid. The flow path 18 is sandwiched and joined by a joint 24 to be integrated. A discharge-side guide vane 23 may be provided on the upper surface of the pump casing 21. Further, the joint portion may be formed as a suction side guide vane in the lubricating liquid suction flow path 18.

  The rotary shaft 20 of the lift pump 12 is supported by radial bearings 25 and 26 and a thrust bearing 27 in the canned motor 12c. An annular lift pump mounting flange 22 a is provided in the motor housing 22, and the lift pump 12 is fastened and fixed to the bearing housing 10 in a state of being inserted into a hole 10 a provided in the lower portion of the bearing housing 10.

  The hydraulic pressure introducing hole 11b of each bearing pad 11 of the lower bearing pad 3 and the corresponding through hole 1g of the bearing lower cover 1b are communicated by a universal joint 16. As shown in FIG. 6, the universal joint 16 has a cylindrical tube shape having a spherical head at both ends, and is provided in the hydraulic pressure introducing hole 11b of each bearing pad 11 of the lower bearing pad 3 and the bearing lower cover 1b. The O-ring 28 is attached to the spherical head so as to be inserted into the through-hole 1g and sealed with the pressurized lubricating liquid. For this reason, the bearing pads 11 and the lower bearing cover 1b of the lower bearing pad 3 are allowed to be displaced relative to the universal joint 16 in the joint axial direction and the direction perpendicular to the axis. And while ensuring the sealing of the lubricating liquid, the complicated movement of the bearing disk 5 during the rotation of the spindle 6 is not suppressed.

  The connection between the fluid pressure introducing hole 11b of each bearing pad 11 of the lower bearing pad 3 and the through hole 1g of the bearing lower cover 1b is not limited to the universal joint 16, and may be connected by a flexible tube or the like.

  When the lift pump 12 rotates, the lubricating liquid is sucked from the bearing housing 10 and led to the hydraulic pressure introducing holes 11b of the bearing pads 11 of the lower bearing pad 3 through the impeller 11a, and the bearing disk 5 is levitated. Then, it flows out into the bearing housing 10 again.

  Since the impeller 12a of the lift pump 12 is located in the bearing housing 10 and the suction flow path and the discharge flow path are also disposed in the bearing housing 10, the lubricating liquid pipe can be eliminated outside the bearing housing 10 and rotated. There is no risk of leakage due to vibration, pressure, temperature fluctuation, etc. of the machine body.

  The outer diameter of the part inserted into the bearing housing 10 of the impeller 12a of the lift pump 12, the pump casing 21 (consisting of the pump casing upper member 21a and the pump casing lower member 21b), and the motor housing 22 is a bearing. The outer diameter of the hole provided in the bottom surface of the housing 10 is smaller. Therefore, the lift pump 12 can be inserted and removed integrally from the bottom of the bearing housing 10 to the bearing lower cover 1b. The pressure-resistant connection location can be only the seal surface between the flange 22a portion provided on the motor casing 22 of the lift pump 12 and the bearing housing 10, and the lift pump 12 itself is configured as a sealless pump. Even when the lubricating liquid has a high pressure, the possibility of leakage can be reduced.

  The lift pump 12 may not be a canned motor pump, but may be a so-called poly-winding motor pump in which a motor coil conductor is water-resistant coated.

  FIG. 5 is a view showing a cross-sectional structure of a sealless vertical submersible motor pump using the pad type thrust bearing shown in FIG. 4 as the thrust bearing. As shown in the figure, this vertical submersible motor pump includes a pump part P and a motor part M, and a bearing housing 10 of a pad type thrust bearing 30 shown in FIG. 4 is fixed to the bottom surface of a motor casing 41 of the motor part M. It is a configuration. The motor part M of the vertical submersible motor pump is a canned motor having a structure in which a stator 44 having a stator winding 43 mounted on a stator iron core 42 is fitted and fixed in a motor casing 41, and the stator 44 is covered with a can 45. is there.

  A rotor 48 is disposed at the center of the stator 44 so as to be fixed to the rotary shaft 40, and the bearing disk 5 of the pad-type thrust bearing 30 is fixed to the lower end of the rotary shaft 40, and the rotary shaft 40 has a thrust direction. It is supported by the pad type thrust bearing 30 and is supported by radial bearings 46 and 47 arranged in the motor casing 41 in the radial direction. The pump part P has a configuration in which a pump impeller 52 fixed to the upper end of the rotary shaft 40 is disposed in the pump casing 51.

  In the submerged motor pump configured as described above, since the weights of the rotor 48, the pump impeller 52, the rotating shaft 40, etc. of the submerged motor act on the pad type thrust bearing 30, a lubricating liquid film is formed. When the pump is not started, solid friction may occur in the bearing portion, and the bearing may be gnawed. However, here, if the bearing disk 5 is lifted by the lift pump 12 and started, the risk of galling of the bearing is eliminated.

  The submerged motor pump having such a structure can be used for a large-sized sealless motor pump that has a high internal pressure of 70 to 160 bar and does not allow leakage of the internal liquid, such as a nuclear reactor cooling water circulation pump. For example, if an attempt is made to employ a large sealless pump with an output of 5500 kw as the primary coolant pump for a pressurized water reactor, a stationary stationary weight of about 12 tons acts on the thrust bearing of the pump. If the submersible bearing is a pad-type thrust bearing having a diameter of about 900 mm, when the bearing disk is levitated by the lift pump 8 (see FIG. 2) of the external pressurizing pump type, the lift of the lift pump 8 has a resistance against internal pressure. In consideration of this, about 164 bar is required.

  In this case, the pressure required for the levitation control of the rotating body can be estimated to be 4 bar, and the rotating body moves to the upper bearing pad 2a side and is fixed only by 10%, that is, 0.4 bar higher than this. That is, in the case of the external lift pump 8, stable levitation cannot be maintained unless the set allowable value of the discharge pressure is controlled with an accuracy of 0.25% with respect to 164 bar. On the other hand, when the lift pump 12 is built in the bearing housing 10 as in the present embodiment, the lift is only 4 bar, which is necessary for the floating body, so that the power is about 1/41 and the setting accuracy is 0.4 bar. That is, the rotating body can be floated and maintained sufficiently stably with an accuracy of about 10%.

  In the present embodiment, when the lift pump 12 and the bearing housing 10 are coupled, the pressure-resistant seal portion that forms a boundary with the ambient atmosphere is only the mounting portion between the motor housing and the bearing housing 10 of the lift pump 12. The reliability with respect to the leakage of the internal liquid can be increased as compared with the case where piping is installed outside the bearing housing 10. Further, it is only necessary to remove the lift pump 12 integrally from the bearing housing 10 during maintenance, and the work can be performed in a short time. By using a small sealless motor pump of the same type as the main body pump for the lift pump 12 as well, high reliability equivalent to that required for the main body as a whole pump can be secured.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Can be modified.

  In the present invention, since the impeller of the lift pump is provided in the bearing housing of the thrust bearing, the pad type thrust bearing and the thrust bearing that can prevent the leakage of the lubricating liquid even when the lubricating liquid becomes a high pressure are provided in the thrust bearing. The present invention can be used to provide a submerged motor including a pad type thrust bearing and a vertical submerged motor pump.

DESCRIPTION OF SYMBOLS 1 Bearing cover 2 Upper bearing pad 3 Lower bearing pad 4 Bearing pad 5 Bearing disk 6 Rotating shaft 7 Tilt mechanism 8 Lift pump 9 Liquid storage tank 10 Bearing housing 11 Bearing pad 12 Lift pump 16 Universal joint 17 Lubricant flow path cover 18 Lubrication Liquid passage 19 Leg 20 Rotating shaft 21 Pump casing 22 Motor housing 23 Discharge side guide vane 24 Joint 25 Radial bearing 26 Radial bearing 27 Thrust bearing 28 O-ring 30 Pad type thrust bearing 40 Rotating shaft 41 Motor casing 42 Stator core 43 Stator Winding 44 Stator 45 Can 46 Radial bearing 47 Radial bearing 48 Rotor 52 Pump impeller

Claims (6)

A pad type thrust bearing provided with a lift pump that pressurizes and supplies a lubricating liquid to the pad surface,
The lift pump, the impeller of the lift pump is coupled in provided in the bearing housing Rutotomoni, is part of the motor housing of the motor for driving the lift pump is inserted into the bearing housing of the thrust bearing A pad-type thrust bearing characterized by being made . In the pad type thrust bearing according to claim 1 ,
The pad type thrust bearing, wherein the lift pump is a sealless motor pump. The pad type thrust bearing according to claim 2 ,
A pad-type thrust bearing, wherein the sealless lift pump is structured to be integrally removable from the outside of the bearing housing. A pad type thrust bearing provided with a lift pump that pressurizes and supplies a lubricating liquid to the pad surface,
A pad type thrust bearing, wherein a motor housing of a sealless motor pump constituting the lift pump is coupled with a bearing housing of the thrust bearing so as to form a sealing surface of the lubricating liquid. Vertical fluid motor comprising the pad-type thrust bearing according to any one of claims 1 to 4. A vertical submersible motor pump comprising the vertical submersible motor according to claim 5 .

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