JP2007056687A - Centrifugal pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal pump in which unpredicted vibration generated in the axial direction of a spindle is effectively reduced. <P>SOLUTION: A thrust collar 20 fixed to the spindle 2 as a thrust bearing mechanism is held in a rear side bearing box 15 formed integrally with a casing. A thrust bearing 21 held by a carrier ring 22 finely movably in the axial direction is disposed in the bearing box 15. A ring 22 is biased by a disc spring 24 between a disk-like liner 23 fixed thereto and an annular member 25 fixed to the bearing box 15. The disc spring 24 is stored in a space 40 formed by the inner surface of the liner 23, the inner surface of the tubular member 25, the outer peripheral surface of a second tubular projected part 25a, and the inner peripheral surface of a third tubular projected part 25b. The internal volume of the space 40 is changed due to the fine movement by the axial vibration of the spindle 2. A passage formed of a first fine clearance 41 between the inner peripheral surface of a first tubular projected part 23a and the outer peripheral surface of a third tubular projected part 25b communicates with the space 40 and is filled with a lubricating oil. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a centrifugal pump that includes a thrust balance mechanism and a thrust bearing mechanism, and that introduces a fluid and pumps it to the outside, and in particular, can effectively reduce unexpected vibrations that occur in the axial direction of a main shaft during operation. It relates to a centrifugal pump.

  In general, during operation of the centrifugal pump, an unbalance occurs in the force acting on the shrouds before and after the impeller, and so-called impeller thrust is generated toward the suction side with respect to the impeller. This impeller thrust acts on the main shaft on which the impeller is fixed as an axial thrust, that is, a thrust load. Therefore, an excessive load is applied to the thrust bearing mechanism that receives the impeller as the thrust load increases. As a result, the mechanical loss of the thrust bearing mechanism is increased, and the mechanical efficiency of the centrifugal pump is unexpectedly reduced.

  Therefore, conventionally, there is a centrifugal pump provided with a thrust balance mechanism that automatically balances axial thrust for the purpose of receiving and reducing the thrust load mainly (see, for example, Patent Document 1). For example, as shown in FIG. 9, the centrifugal pump 100 is a multistage type in which the impeller 1 is connected in a plurality of stages (three stages in FIG. 9). A main shaft 2 that rotates in the casing, an impeller 1 that is fixed to the main shaft 2 and that pumps fluid by introducing a fluid, a thrust balance mechanism, and a thrust bearing mechanism are provided. The casing includes a suction casing 4 provided with a fluid suction port 3, a discharge casing 6 provided with a fluid discharge port 5, and a plurality of casings arranged in the axial direction of the main shaft 2 between the suction casing 4 and the discharge casing 6. These intermediate casings 7 are integrally fastened by a plurality of fastening bolts 8 and nuts 9. The multi-stage impeller 1 is fixed to an intermediate portion of the main shaft 2.

  A front stuffing box 10 through which the main shaft 2 is rotatably fitted is fixed to the front end (left side in FIG. 9) of the suction casing 4, and the rear end (right side in FIG. 9) is also rearward in the same manner. The side stuffing box 11 is fixed. In addition, a front bearing box 13 having a radial bearing 12 for supporting the front side of the main shaft 2 is disposed integrally with the suction casing 4 outside the front end of the front stuffing box 10. On the other hand, on the outer side of the rear end of the rear stuffing box 11, a rear bearing box 15 having a radial bearing 14 that supports the rear side of the main shaft 2 is disposed integrally with the discharge casing 6. Further, a driving machine 16 for rotating the main shaft 2 is connected to the front end of the main shaft 2.

  Further, the rear bearing box 15 constitutes a part of a thrust bearing mechanism, and is inserted into the main shaft 2 and fixed coaxially therewith as shown in FIGS. 9 and 10. The disc-shaped thrust collar 20, a pair of thrust bearings 21 that sandwich the thrust collar 20 from both sides, and each thrust bearing 21 together with the thrust collar 20, while holding the thrust bearings 21 in the axial direction with respect to the rear bearing box 15. A carrier ring 22 arranged to be movable, a disk-shaped liner 23 fixed to the front end surface (left side in FIGS. 9 and 10) of the carrier ring 22, and one end abutting against the disk-shaped liner 23, A disc spring 24, which is a spring body that urges the disc-shaped liner 23 together with the thrust collar 20, the thrust bearings 21, and the carrier ring 22 toward the rear bearing box 15 in the axial direction, An annular member 25 which is fixed to the bearing housing 15 in contact with the other end of the conical spring 24 and holds it, is provided. As a result, a thrust bearing mechanism that supplementarily receives the thrust load of the main shaft 2 is configured. Here, the inside of the rear bearing box 15 is filled with lubricating oil as a lubricant for the thrust bearing 21, but this lubricating oil is appropriately injected from an oil supply port 26 connected to an oil supply pump (not shown), It is discharged from the main oil outlet 27.

  Next, the thrust balance mechanism will be described. As shown in FIGS. 9 and 11, the main shaft 2 is inserted between the impeller 1 and the rear stuffing box 11 located on the most discharge side, that is, the rear side (right side in FIG. 9) in the discharge casing 6. The balance disk 30 composed of a tubular portion 30a fitted and fixed coaxially therewith, and a disk portion 30b formed at the rear end (right side in FIGS. 9 and 11) of the tubular portion 30a, and the discharge casing 6 The first balance bush 31 including the first cylindrical portion 31a and the first flange portion 31b that are respectively fixed to the outer peripheral surface of the tubular portion 30a and the inner surface of the disc portion 30b of the balance disc 30, and the balance disc 30. A second cylindrical portion 32a facing the outer peripheral surface of the disk portion 30b and a second flange portion formed at the rear end of the second cylindrical portion 32a Second balancing bush 32 made of 2b, a balance sheet 33 composed of, it is provided.

  Here, the balance disk 30 is fixed to the main shaft 2 with the split ring 35 fitted in the ring groove 34 on the outer peripheral surface of the main shaft 2 with respect to the rear end surface of the impeller 1. The outer surface on the inner peripheral side is pressed down, and the fixing ring 36 on which the split ring 35 is hooked is fastened to the disk portion 30b with a bolt. On the other hand, the balance sheet 33 is fixed to the discharge casing 6 on the outer surface of the first flange portion 31b of the first balance bush 31 fitted in the discharge casing 6 on the outer surface of the second cylindrical portion 32a of the second balance bush 32. This is done by bringing the front end face into contact and fastening it to the discharge casing 6 with a bolt.

  In such a balance disc 30 and balance sheet 33, a gap t1 between the outer peripheral surface of the tubular portion 30a and the inner peripheral surface of the first cylindrical portion 31a, and a gap between the inner surface of the disc portion 30b and the outer surface of the first flange portion 31b. t2 and a gap t3 between the outer peripheral surface of the disk portion 30b and the inner peripheral surface of the second cylindrical portion 32a are formed. Here, the gap t2 is displaced by the axial movement of the main shaft 2 accompanying the fluctuation of the axial thrust. These gaps t1 to t3 form a continuous flow path through which fluid can flow, and one end of the flow path communicates with the vicinity of the discharge port 5 in the discharge casing 6 and the other end of the balance disk 30 and the rear stuffing box. 11 is communicated with a balance chamber 37 formed by. The balance chamber 37 is connected to the vicinity of the suction port 3 in the suction casing 4 via a balance pipe 38.

  Under such a configuration, during operation of the centrifugal pump 100, the impeller thrust toward the suction side, that is, the axial front of the main shaft 2 (leftward in FIGS. 9 and 11) with respect to each impeller 1. This impeller thrust is transmitted to the main shaft 2 as an axial thrust. On the other hand, a part of the fluid discharged from the impeller 1 to the discharge port 5 is introduced into the flow path formed by the gaps t1 to t3 in the balance disk 30 and the balance sheet 33, and is led to the balance chamber 37, and finally. Is led to the suction port 3 through the balance pipe 38. At that time, the pressure in the balance chamber 37 becomes lower than the pressure on the discharge port 5 side due to the pressure loss in the flow path. As a result, due to the differential pressure, a balance thrust is generated on the balance disk 30 in the axial rearward direction of the main shaft 2 (rightward in FIGS. 9 and 11). The balance thrust is transmitted from the balance disk 30 to the main shaft 2 via the split ring 35, and acts on the main shaft 2 so as to cancel the impeller thrust.

  For example, when the impeller thrust increases and the axial thrust acting on the main shaft 2 increases, the main shaft 2 is displaced forward in the axial direction, and the gap t2 between the balance disk 30 and the balance sheet 33 decreases. Then, since the pressure loss in the gap t2 increases, the balance thrust generated in the balance disk 30 increases corresponding to the increased impeller thrust, and the main shaft 2 is in the original position even if it is displaced rearward in the axial direction. Return. On the contrary, when the impeller thrust is reduced, the main shaft 2 is displaced rearward in the axial direction, and the gap t2 is increased. Then, since the pressure loss in the gap t2 is reduced, the balance thrust generated in the balance disk 30 is reduced corresponding to the reduced impeller thrust, and the main shaft 2 is in the original position even when displaced forward in the axial direction. Return.

Thus, the thrust balance mechanism automatically balances the axial thrust acting on the main shaft 2 so as to correspond to the increase and decrease of the impeller thrust by the fluid leaking the gaps t1 to t3 in the balance disk 30 and the balance sheet 33. Make it possible. That is, the thrust load is mainly received and reduced.
JP 2000-249090 A (page 3)

  Meanwhile, in the centrifugal pump 100 described above, the main shaft 2 vibrates in the axial direction mainly due to fluctuations in the axial thrust during operation. As shown in FIG. 12, this axial vibration is caused by the spring constant Kd indicating the rigidity of the fluid in the gaps t1 to t3 between the balance disk 30 and the balance sheet 33, its damping coefficient Cd, the spring constant Ks of the split ring 35 and its Damping is performed by a vibration system constituted by the damping coefficient Cs, the spring constant Kt of the thrust bearing 21 and its damping coefficient Ct, and the spring constant Kss of the disc spring 24.

  However, in the centrifugal pump 100 having such a vibration system, if sufficient attenuation of the entire system cannot be obtained, unexpected axial vibration occurs. If the vibration is large, contact / wear of the balance disk, thrust bearing Possible damage. In particular, the frequency of occurrence of unexpected axial vibrations is high in a high-power centrifugal pump that is used in a large boiler and used for water absorption or the like.

  Therefore, the present invention has been made in view of the above problems, and a thrust balance mechanism for balancing axial thrust acting on the main shaft, and a thrust bearing mechanism for supplementarily receiving the thrust load of the main shaft, The purpose of the present invention is to provide a centrifugal pump that can effectively reduce unexpected vibrations that occur in the axial direction of the main shaft during operation.

  In order to achieve the above object, a centrifugal pump according to the present invention is a casing having a suction port and a discharge port, and is fixed to a main shaft that rotates in the casing, and fluid is introduced from the suction port and is pumped to the discharge port. An impeller, a balance disk fixed to the main shaft, and a balance sheet fixed to the casing and opposed to the balance disk, and an axial thrust acting on the main shaft through a gap formed by the mutually facing surfaces. A thrust balance mechanism that balances by the leaking fluid, a thrust collar fixed to the main shaft, a thrust bearing that sandwiches the thrust collar and is disposed so as to be capable of minute movement in the axial direction with respect to the casing, and the thrust Consists of a spring body that biases the bearing in the axial direction against the casing, assisting the thrust load of the main shaft A thrust bearing mechanism that receives the spring body, a space in which the spring body is accommodated and the internal volume is displaced in accordance with the minute movement of the main shaft in the axial direction, and communicates with the space. A communication passage having a minute gap passage along at least the axial direction of the main shaft, and the space and the communication passage are filled with liquid.

  As a result, the internal volume of the space containing the spring body is displaced along with the minute movement of the main shaft in the axial direction, that is, axial vibration. At this time, the liquid filled in the space and the communication passage is resisted by the passage. It flows while receiving. That is, a kind of liquid damper is formed, and even if an unexpected axial vibration occurs, the vibration is surely reduced.

  Here, in consideration of practicality, the spring body is a metal disc spring that is coaxial with the main shaft, and the thrust bearing is a disc shape that is coaxial with the main shaft and contacts one end of the disc spring. A liner is fixed, and an annular member that is in contact with the other end of the disc spring and is opposed to the disk-shaped liner is fixed to the casing, and is coaxial with the main shaft near the outer periphery of the disk-shaped liner. A first cylindrical protrusion that protrudes toward the annular member is provided, and a second cylindrical protrusion that is coaxial with the main shaft and protrudes toward the disk-shaped liner is provided in the vicinity of the inner periphery of the annular member. A third portion that is coaxial with the main shaft and protrudes toward the disk-shaped liner, and is opposed to the first cylindrical protrusion with a minute gap therebetween. It is preferable that a cylindrical protrusion is provided. Thereby, the space is formed from the inner surface of the disk-shaped liner, the inner surface of the tubular member, the outer peripheral surface of the second cylindrical projection, and the inner peripheral surface of the first cylindrical projection or the third cylindrical projection. The passage is formed with the outer peripheral surface of the first cylindrical protrusion and the inner peripheral surface of the third cylindrical protrusion, or the inner peripheral surface of the first cylindrical protrusion and the third cylindrical protrusion. It can form from the outer peripheral surface.

  Assuming that the unexpected axial vibration is excessive, it is effective to increase the number of locations that function as liquid dampers.In light of this, in the vicinity of the inner periphery of the disc-shaped liner, It is preferable that a fourth cylindrical protrusion that is coaxial with the main shaft and protrudes toward the annular member and is opposed to the second cylindrical protrusion with the minute gap therebetween is provided. Thereby, in addition to the one place formed by the first cylindrical projection and the third cylindrical projection described above, the passage is provided with the outer peripheral surface of the second cylindrical projection and the fourth cylindrical projection. It can form from the inner peripheral surface of a part, or the inner peripheral surface of a 2nd cylindrical projection part, and the outer peripheral surface of a 4th cylindrical projection part.

  Further, if the lubricant filled around the thrust bearing can be utilized conventionally, there is no need to newly provide a liquid supply mechanism for the liquid damper. Therefore, the lubricant is supplied with the lubricating oil supplied to the thrust bearing mechanism itself. There should be.

  According to the centrifugal pump of the present invention, a casing having a suction port and a discharge port, an impeller that is fixed to a main shaft that rotates in the casing, introduces fluid from the suction port, and pumps the fluid to the discharge port, The balance disk is fixed to the main shaft and the balance sheet is fixed to the casing and faces the balance disk. The axial thrust acting on the main shaft is balanced by the fluid leaking through the gap formed between the opposing surfaces. A thrust balance mechanism that is fixed to the main shaft, a thrust bearing that is sandwiched by the thrust collar so as to be capable of minute movement in the axial direction with respect to the casing, and the thrust bearing to the casing Thrust consisting of a spring body biased in the axial direction to receive the thrust load of the main shaft in an auxiliary manner In the centrifugal pump comprising a receiving mechanism, as the thrust bearing mechanism, a space in which the spring body is accommodated and an internal volume is displaced with a minute movement in the axial direction of the main shaft, and at least the main shaft communicating with the space And the space and the communication path are filled with liquid, so that the space containing the spring body is moved in the axial direction of the main shaft, The internal volume is displaced with the vibration in the axial direction. At this time, the liquid filled in the space and the communication passage flows while receiving resistance in the passage. Therefore, since a kind of liquid damper is formed, even if an unexpected axial vibration occurs, the vibration can be surely reduced.

  Here, the spring body is a metal disc spring coaxial with the main shaft, and the thrust bearing is fixed with a disk-shaped liner coaxial with the main shaft and abutting with one end of the disc spring, An annular member that is in contact with the other end of the disc spring and faces the disc-shaped liner is fixed to the casing, and the outer periphery of the disc-shaped liner is coaxial with the main shaft toward the annular member. A protruding first cylindrical protruding portion is provided, and in the vicinity of the inner periphery of the annular member, a second cylindrical protruding portion that is coaxial with the main shaft and protrudes toward the disk-shaped liner is provided, In the vicinity of the outer periphery of the annular member, there is provided a third cylindrical protruding portion that is coaxial with the main shaft and protrudes toward the disk-shaped liner and is opposed to the first cylindrical protruding portion with a minute gap therebetween. The inner space of the disc-shaped liner, the inner part of the tubular member , The outer peripheral surface of the second cylindrical projection, and the inner peripheral surface of the first cylindrical projection or the third cylindrical projection, the passage is the outer peripheral surface of the first cylindrical projection And can be formed from the inner peripheral surface of the third cylindrical projection, or the inner peripheral surface of the first cylindrical projection and the outer peripheral surface of the third cylindrical projection, and is practical with a simple configuration. .

  Further, in the vicinity of the inner periphery of the disk-shaped liner, a fourth cylindrical protrusion that is coaxial with the main shaft and protrudes toward the annular member and faces the second cylindrical protrusion with a small gap therebetween. If the portion is provided, in addition to the one place formed by the first cylindrical protrusion and the third cylindrical protrusion described above, the passage is provided with the outer peripheral surface of the second cylindrical protrusion and the first Since it can be formed from the inner peripheral surface of the four cylindrical projections, or the inner peripheral surface of the second cylindrical projection and the outer peripheral surface of the fourth cylindrical projection, the number of locations that function as liquid dampers can be increased. Even if the unexpected axial vibration is excessive, the axial vibration can be effectively reduced.

  Further, when the liquid is a lubricating oil supplied to the thrust bearing mechanism itself, it is possible to utilize a lubricant that has been filled around the thrust bearing conventionally, and a new liquid supply mechanism for a liquid damper. This is economical.

  Hereinafter, embodiments of the centrifugal pump of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described. 1 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to a first embodiment, FIG. 2 is a diagram schematically showing a vibration system of the centrifugal pump, and FIG. 3 is a principle of a liquid damper for damping vibrations. It is explanatory drawing. The feature of the present invention is that the thrust bearing mechanism has been devised. In the figure, parts having the same names and functions that are the same as those in FIGS. Then, it abbreviate | omits and demonstrates a different point. The same applies to the second to sixth embodiments described later.

  As shown in FIG. 1, as a thrust bearing mechanism for receiving the thrust load of the main shaft 2, a disc-like shape is inserted into the main shaft 2 and is fixed coaxially with the main shaft 2. A thrust collar 20, a pair of thrust bearings 21 that sandwich the thrust collar 20 from both sides, and the thrust bearings 20 are held together with the thrust collars 20, and the rear bearing box 15 can be moved minutely in the axial direction. The carrier ring 22 provided, a disk-like liner 23 fixed to the front end surface (left side in FIG. 1) of the carrier ring 22, and one end abutting against the disk-like liner 23, the thrust collar 20 and each thrust bearing 21 , And the carrier ring 22, and the disc-shaped liner 23 is made of a metal that is a spring body that urges the rear bearing box 15 toward the rear axial direction (rightward in FIG. 1). An annular member 25 for holding the springs 24, disc spring 24 is fixed to the rear bearing housing 15 and the other end abuts with this, is provided.

  That is, the disc spring 24 is housed while having elastic repulsion between the inner surfaces of the disk-shaped liner 23 and the annular member 25 facing each other, and accompanies the axial vibration of the main shaft 2. A slight movement of the thrust collar 20 in the axial direction (shown by a solid double arrow in FIG. 1) can be permitted via each thrust bearing 21, carrier ring 22 and disk-like liner 23, and thereby the thrust load applied to each part can be allowed. Reduce the load auxiliary. The main function of the disc spring is to prevent the balance disk and the thrust bearing from coming into contact and wear when the self-balance function of the balance disk does not occur, such as when starting and stopping.

  Here, in the vicinity of the outer periphery of the disc-shaped liner 23, a first cylindrical protruding portion 23a that is coaxial with the main shaft 2 and protrudes toward the annular member 25 is provided, and in the vicinity of the inner periphery of the other annular member 25, Similarly, the second cylindrical protruding portion 25a that is coaxial with the main shaft 2 and protrudes toward the disc-shaped liner 23 is provided in the vicinity of the outer periphery of the annular member 25 in the same manner as the second cylindrical protruding portion 25a. Cylindrical protrusions 25b are respectively provided. Further, in the vicinity of the inner periphery of the disc-like liner 23, a fourth cylindrical protrusion 23b that is coaxial with the main shaft 2 and protrudes toward the annular member 25 is provided in the same manner as the first cylindrical protrusion 23a. ing.

  In particular, in the present embodiment, the first cylindrical projecting portion 23a, the third cylindrical projecting portion 25b, the fourth cylindrical projecting portion 23b, the first cylindrical projecting portion 23b, in order from the radially outer side to the inner side with respect to the main shaft 2. Two cylindrical protrusions 25a, the inner peripheral surface of the first cylindrical protrusion 23a and the outer peripheral surface of the third cylindrical protrusion 25b are opposed to each other with the first minute gap 41 therebetween, Similarly, the inner peripheral surface of the fourth cylindrical protrusion 23 b and the outer peripheral surface of the second cylindrical protrusion 25 a are opposed to each other with the second minute gap 46 therebetween. Therefore, the first and second minute gaps 41 and 46 are both in the form along the axial direction of the main shaft 2. However, in the present embodiment, the height of the fourth cylindrical protruding portion 23b is lower than the other first to third cylindrical protruding portions 23a, 25a, and 25b.

  With such a configuration, the disc spring 24 has the inner surface of the disk-shaped liner 23, the inner surface of the tubular member 25, the inner peripheral surface of the third cylindrical projecting portion 25b, and the outer periphery of the second cylindrical projecting portion 25a. It is in a state of being accommodated in a space 40 formed from a surface (strictly speaking, a part of the outer peripheral surface of the fourth cylindrical protrusion 23b is also included). The internal volume of the space 40 is displaced by a minute movement in the axial direction of the thrust collar 20 (the disk-like liner 23 that responds to the thrust collar) accompanying the axial vibration of the main shaft 2. The disk-shaped liner 23 is fastened to the carrier ring 22 with bolts or the like. However, the disk-shaped liner 23 and the carrier ring 22 integrated with the disk-shaped liner 23 are inadvertently moved by the minute movement in the axial direction. The disc-like liner 23 is supported by an O-ring 45 with respect to the rear bearing box 15 and the annular member 25 so as to exhibit a liquid damper function to be described later while preventing friction with each other.

  The rear bearing box 15 is filled with lubricating oil as a lubricant for the thrust bearing 21. This lubricating oil is appropriately injected from an oil supply port 26 connected to an oil supply pump (not shown), most of which is discharged from the main oil discharge port 27, but a part of the lubricating oil is a second cylinder of the annular member 25. A discharge port 47 formed outside the third cylindrical projection 25a in the annular member 25 is introduced into the space 40 from the suction port 46 formed in the cylindrical projection 25a, and further through the first minute gap 41. And finally discharged from the auxiliary oil outlet 28 formed in the rear bearing box 15. That is, the first minute gap 41 is a passage that communicates with the space 40 and flows the lubricating oil.

  According to the thrust bearing mechanism having such a configuration, the space 40 in which the disc spring 24 is accommodated is displaced in the internal volume due to minute movement of the main shaft 2 in the axial direction, that is, axial vibration. In accordance with the displacement of the space 40, a kind of liquid damper is formed in which the lubricating oil flows while receiving resistance in the passage formed by the first minute gap 41. That is, as shown in FIG. 3, in principle, the viscous fluid filled in the cylinder is formed by a minute gap formed between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder as the piston reciprocates. A configuration of a liquid damper that flows while receiving resistance is obtained, and this makes it possible to attenuate vibrations. Accordingly, as shown in FIG. 2, the vibration system of the centrifugal pump 100 includes a conventional spring constant Kd indicating the rigidity of the fluid in the gaps t1 to t3 between the balance disk 30 and the balance sheet 33, its damping coefficient Cd, and split. In addition to the spring constant Ks of the ring 35 and its damping coefficient Cs, the spring constant Kt of the thrust bearing 21 and its damping coefficient Ct, and the spring constant Kss of the disc spring 24, the damping of the lubricating oil (liquid damper) around the disc spring 24 Therefore, even if an unexpected axial vibration occurs, the vibration can be reliably reduced. Of course, it is also effective against axial vibrations that occur in normal operating conditions.

  Further, in this embodiment, since it is possible to utilize the lubricating oil that has been filled in the rear bearing box 15 as a lubricant for the thrust bearing 21 conventionally, a liquid supply mechanism for a liquid damper is newly added. There is no need to provide a battery, and there is an effect that it is economical, and it can be said that it is practical with a simple configuration.

  In the present embodiment, the lubricating oil filled in the space 40 is discharged from the auxiliary oil outlet 28 through the outlet 47, but as an idea to prevent the amount of discharge from being excessive, the oil is discharged. One outlet 47 is provided in the radial direction. In addition, radial grooves are formed on the inner surface of the disc-like liner 23 and the inner surface of the annular member 25 that are in contact with both ends of the disc spring 24, so that the lubricating oil can flow smoothly in the grooves. Yes.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to the second embodiment. The feature of the second embodiment is that the formation portion of the first minute gap 41 in the first embodiment is changed.

  In the present embodiment, as shown in FIG. 4, the third cylindrical projecting portion 25 b, the first cylindrical projecting portion 23 a, and the fourth tube are sequentially arranged from the radially outer side to the inner side with respect to the main shaft 2. A cylindrical protrusion 23b and a second cylindrical protrusion 25a are formed, and the inner peripheral surface of the third cylindrical protrusion 25b and the outer peripheral surface of the first cylindrical protrusion 23a are the first minute gap 41. They are designed to face each other. That is, the first minute gap 41 serving as a lubricant passage functioning as a liquid damper is formed by the inner peripheral surface of the third cylindrical protrusion 25b and the outer peripheral surface of the first cylindrical protrusion 23a. . Even if it does in this way, it will become possible to show the same effect as a 1st embodiment mentioned above. In the case of the present embodiment, the space 40 that accommodates the disc spring 24 includes the inner surface of the disk-shaped liner 23, the inner surface of the tubular member 25, the inner peripheral surface of the first cylindrical protrusion 23a, and the second cylindrical shape. It is formed from the outer peripheral surface of the protrusion 25a.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to the third embodiment. The feature of the third embodiment is that assuming that the unexpected axial vibration is excessive, it is effective to increase the number of locations that function as liquid dampers. Therefore, based on this, the first embodiment is modified. It is in the point.

  In the present embodiment, as shown in FIG. 5, the height of the fourth cylindrical projecting portion 23 b is extended, and the space 40 for accommodating the disc spring 24 is the inner surface of the disc-shaped liner 23, the tubular member 25. It is formed from the inner surface, the inner peripheral surface of the third cylindrical protrusion 25b, and the outer peripheral surface of the fourth cylindrical protrusion 23b. If it does so, the 2nd minute gap 42 which consists of the inner peripheral surface of the 4th cylindrical projection part 23b and the outer peripheral surface of the 2nd cylindrical projection part 25a becomes a channel | path which communicates with the space 40 and lubricating oil flows.

  In this way, since the two passages, the passage formed by the first minute gap 41 and the passage formed by the second minute gap 42, communicate with the space 40, the liquid damper function is the first. This is an improvement over the embodiment. Of course, such a passage formed by the second minute gap 42 may be provided in the second embodiment.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to the fourth embodiment. As in the third embodiment, the fourth embodiment is characterized in that the first embodiment is modified for the purpose of increasing the number of locations that function as liquid dampers.

  In the present embodiment, as shown in FIG. 6, the outer third cylindrical projecting portion 25 b 1, the first cylindrical projecting portion 23 a, and the inner inner shaft 2 in order from the radially outer side to the inner side with respect to the main shaft 2. The third cylindrical projecting portion 25b2, the fourth cylindrical projecting portion 23b, and the second cylindrical projecting portion 25a, and the first minute gap 41 serving as a lubricant passage functioning as a liquid damper, A minute gap 41a between the inner peripheral surface of the outer third cylindrical projecting portion 25b1 and the outer peripheral surface of the first cylindrical projecting portion 23a, and the inner peripheral surface of the first cylindrical projecting portion 23a and the inner third surface. Formed by a minute gap 41b with the outer peripheral surface of the cylindrical protrusion 25b2.

  In this way, the first minute gap 41 communicating with the space 40 is extended as compared with the first embodiment, so that the liquid damper function is improved. Here, an auxiliary space 43 that is displaced in the same manner as the space 40 is formed at the connection point between the minute gap 41a and the minute gap 41b in the path of the first minute gap 41, and this functions as a liquid damper. This is to divide the first minute gap 41 so as to substantially increase the number of locations. In the case of the present embodiment, the space 40 that accommodates the disc spring 24 includes the inner surface of the disc-shaped liner 23, the inner surface of the tubular member 25, the inner peripheral surface of the inner third cylindrical protrusion 25b2, and the second inner surface. It is formed from the outer peripheral surface of the cylindrical protrusion 25a.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to a fifth embodiment. The feature of the fifth embodiment is that the components of the fourth embodiment described above are simplified.

  In the present embodiment, as shown in FIG. 7, the space 40 that accommodates the disc spring 24 includes an inner surface of the disk-shaped liner 23, an inner surface of the tubular member 25, an inner peripheral surface of the inner third cylindrical protrusion 25 b 2, Of these, the outer peripheral surface of the second cylindrical projection 25a is formed, and among these, the corner between the inner surface of the disc-shaped liner 23 and the outer peripheral surface of the second cylindrical projection 25a is largely opened. Yes. That is, the fourth cylindrical protrusion 23b formed in the disk-shaped liner 23 in the fourth embodiment and the suction port 46 formed in the second cylindrical protrusion 25a are excluded.

  Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a longitudinal sectional view showing a thrust bearing mechanism of a centrifugal pump according to the sixth embodiment. The feature of the sixth embodiment is that the components of the above-described embodiments are further simplified.

  In the present embodiment, as shown in FIG. 8, in the vicinity of the outer periphery of the disc-shaped liner 23, a first cylindrical projecting portion that is coaxial with the main shaft 2 and projects axially rearward (rightward in FIG. 8). On the other hand, in the vicinity of the inner periphery, a fourth cylindrical projecting portion 23b ′ that is coaxial with the main shaft 2 and projects rearward in the axial direction is provided. The first minute gap 41 ′ serving as a lubricant passage functioning as a liquid damper is formed by the outer peripheral surface of the first cylindrical protrusion 23a ′ and the inner peripheral surface of the rear bearing box 15, The second minute gap 42 ′ is formed by the inner peripheral surface of the fourth cylindrical protrusion 23 b ′ and the outer peripheral surface of the main shaft 2.

  In the case of this embodiment, the lubricating oil in the space 40 passes through the discharge port 47 ′ formed on the inner surface of the tubular member 25, and the auxiliary oil discharge port formed in the rear bearing box 15 so as to communicate with this. 28 'is discharged.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the arrangement relationship between the fourth cylindrical protruding portion 23b and the second cylindrical protruding portion 25a in the radial direction of the main shaft 2 may be reversed. Further, as long as the function as a liquid damper can be exhibited, the lubricating oil filled in the space 40 and the passage may be another liquid, and this liquid supply mechanism may be newly provided. Further, the disc spring 24 may be a spring body such as a coil spring.

It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 1st Embodiment of this invention. It is a figure which shows typically the vibration system of the centrifugal pump of 1st Embodiment. It is principle explanatory drawing of the liquid damper for attenuating a vibration. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 4th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 5th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the centrifugal pump which is 6th Embodiment of this invention. It is a longitudinal cross-sectional view of the common centrifugal pump common to this invention and the former. It is a longitudinal cross-sectional view which shows the thrust bearing mechanism of the conventional centrifugal pump. It is a longitudinal cross-sectional view which shows the thrust balance mechanism of the conventional centrifugal pump. It is a figure which shows typically the vibration system of the conventional centrifugal pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impeller 2 Main shaft 3 Suction port 4 Suction casing 5 Discharge port 6 Discharge casing 7 Intermediate casing 16 Driver 20 Thrust collar 21 Thrust bearing 22 Carrier ring 23 Disc-shaped liner 24 Disc spring (spring body)
25 annular member 26 oil supply port 27 main oil discharge port 28 auxiliary oil discharge port 30 balance disk 30a tubular part 30b disk part 31 first balance bush 31a first cylinder part 31b first flange part 32 second balance bush 32a second cylinder part 32b Second flange portion 33 Balance sheet 35 Split ring 37 Balance chamber 40 Space 41 First minute gap 42 Second minute gap 46 Suction port 47 Ejection port 100 Centrifugal pump

Claims (4)

A casing having a suction port and a discharge port, an impeller fixed to a main shaft that rotates in the casing and that introduces fluid from the suction port and pumps the fluid to the discharge port, a balance disk fixed to the main shaft, and A thrust balance mechanism that is fixed to the casing and that opposes the balance disk, and that balances the axial thrust acting on the main shaft with a fluid leaking through a gap formed by the opposing surfaces; A fixed thrust collar, a thrust bearing that is sandwiched between the thrust collars so as to be capable of minute movement in the axial direction with respect to the casing, and a spring body that urges the thrust bearing in the axial direction with respect to the casing And a thrust bearing mechanism for supplementarily receiving a thrust load of the main shaft. In,
As the thrust bearing mechanism, a space in which the spring body is accommodated and the internal volume is displaced with a minute movement in the axial direction of the main shaft, and a passage of a minute gap is provided at least along the axial direction of the main shaft. A centrifugal pump comprising: a communication passage having a liquid; and the space and the communication passage are filled with a liquid. The spring body is a metal disc spring coaxial with the main shaft, and a disk-shaped liner coaxial with the main shaft and abutting against one end of the disc spring is fixed to the thrust bearing. The annular member that contacts the other end of the disc spring and faces the disc-shaped liner is fixed,
Near the outer periphery of the disc-shaped liner, there is provided a first cylindrical protrusion that is coaxial with the main shaft and protrudes toward the annular member, and is coaxial with the main shaft near the inner periphery of the annular member. A second cylindrical projecting portion projecting toward the disc-shaped liner is provided, and an outer peripheral portion of the annular member is coaxial with the main shaft and projects toward the disc-shaped liner, The centrifugal pump according to claim 1, further comprising a third cylindrical projecting portion facing the cylindrical projecting portion with the minute gap therebetween.   Further, in the vicinity of the inner periphery of the disk-shaped liner, a fourth cylindrical protrusion that is coaxial with the main shaft and protrudes toward the annular member and faces the second cylindrical protrusion with a small gap therebetween. The centrifugal pump according to claim 2, wherein a portion is provided.   The centrifugal pump according to any one of claims 1 to 3, wherein the liquid is lubricating oil supplied to the thrust bearing mechanism itself.

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