JP2009007960A - Centrifugal pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal pump capable of effectively preventing generation of noise between an end surface of a bearing and the inner bottom surface of a pump housing part, and of extending the life of the pump. <P>SOLUTION: This centrifugal pump is structured such that the pump housing part 7, and a suction port 9 and a discharge port 11 communicating with the pump housing part 7 are formed on a pump case 1; an impeller 6 having the bearing 22 at the center is housed in the pump housing part 7; the bearing 22 of the impeller 6 is journaled by a shaft 23 arranged in the pump housing part 7; and a drive means rotationally driving the impeller 6 around the shaft 23 is provided. A thrust bearing part 32 interposed between an end surface 22a of the bearing 22 located on the suction port 9 side and the inner bottom surface 7c of the pump housing part 7 facing the end surface 22a is projected integrally from the shaft 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal pump having a bearing plate that receives a thrust load of an impeller.

  Conventionally, a pump housing part and a suction port and a discharge port communicating with the pump housing part are formed in the pump case, and an impeller having a bearing in the center is housed in the pump housing part. There is known a centrifugal pump that is supported by a shaft provided in a pump housing portion and includes driving means such as a stator that rotationally drives an impeller around the shaft.

  In this type of centrifugal pump, fluid is pumped out from the center of the impeller toward the outer periphery during driving, so that the vicinity of the suction port of the pump housing has negative pressure, and one end of the impeller bearing is sucked into the suction port side. Is done. Therefore, there is a problem that the end surface of the bearing of the impeller slides on the inner bottom surface of the pump housing portion facing this, and the end surface of the bearing and the inner bottom surface of the pump housing portion are worn.

On the other hand, for example, in Patent Document 1, a ring-shaped bearing plate is interposed between the end surface of the impeller bearing and the inner bottom surface of the pump storage portion, and the impeller bearing is interposed via the bearing plate. What was received is disclosed. However, since the bearing plate is simply configured to be non-rotatably fitted to the shaft, there is a risk that the bearing plate will also rattle between the end surface of the shaft body and the inner bottom surface of the pump housing. There is a problem that abnormal noise is generated due to this, and there is a problem that uneven wear occurs between the end face of the bearing and the bearing plate. In addition, two members of the bearing plate and the shaft are required, and in order to fit the bearing plate to the shaft in a non-rotatable manner, it is necessary to form a fitting portion between the two in a D-cut or the like, which is expensive. There is also.
JP-A-7-103179

  The present invention has been invented in view of the above-described conventional problems, and it is effective to generate abnormal noise and uneven wear between the end surface of the bearing and the inner bottom surface of the pump housing portion with an inexpensive configuration. It is an object of the present invention to provide a centrifugal pump that can prevent the above problem and extend the life of the pump.

  In order to solve the above-described problem, the centrifugal pump of the present invention is formed in the pump case 1 by forming a pump housing portion 7 and a suction port 9 and a discharge port 11 communicating with the pump housing portion 7. In addition, the impeller 6 having the bearing 22 at the center is accommodated, the bearing 22 of the impeller 6 is pivotally supported by the shaft 23 provided in the pump accommodating portion 7, and the impeller 6 is driven to rotate around the shaft 23. In a centrifugal pump comprising means, a thrust bearing portion 32 interposed between an end surface 22a located on the suction port 9 side of the bearing 22 and an inner bottom surface 7c of the pump housing portion 7 facing the end surface 22a is provided as a shaft. Suppose that it protrudes integrally from 23.

  By using the centrifugal pump having the above-described configuration, the suction port 9 side of the pump storage portion 7 becomes negative pressure during pump operation, and the thrust formed integrally with the shaft 23 when the impeller 6 moves to the suction port 9 side. A bearing portion 32 is interposed between the end surface 22 a of the bearing 22 in the center of the impeller 6 and the inner bottom surface 7 c of the pump storage portion 7, and between the end surface 22 a of the bearing 22 and the inner bottom surface 7 c of the pump storage portion 7. Prevent wear.

  Since the thrust bearing portion 32 is provided integrally with the shaft 23, the thrust bearing portion 32 does not rattle during operation. Therefore, there is no problem that abnormal noise is generated during operation or uneven wear occurs between the thrust bearing portion 32 and the bearing 22. Further, there is no need to provide a separate member such as a bearing plate described in Patent Document 1, and it is also necessary to form a fitting portion in a D-cut or the like in order to fit another member such as a bearing plate in a non-rotatable manner. Therefore, it can be provided at a low cost.

  Furthermore, in the centrifugal pump having the above-described configuration, the shaft 23 is perpendicular to the inner bottom surface 7c of the pump housing portion 7 at the end on the suction port 9 side of the shaft 23 in which the thrust bearing portion 32 is integrated. Thus, it is preferable to adhere to the inner bottom surface 7c. By doing in this way, the width | variety of the clearance gap 33 formed between the end surface by the side of the suction inlet 9 of the impeller 6 and the inner bottom face 7c of the pump accommodating part 7 can be kept constant during a driving | operation. A part of the refrigerant is returned through the gap 33 due to the negative pressure in the vicinity of the suction port 9 during operation, thereby preventing the amount of refrigerant returning through the gap 33 from fluctuating greatly. Pump performance can be stabilized. In addition, since the impeller 6 stably rotates around the shaft 23 fixed perpendicularly to the inner bottom surface 7c of the pump storage portion 7, the width of the gap 33 is reduced as much as possible toward the suction port 9 side. The amount of the returning refrigerant can be suppressed and the pump performance can be improved.

  In the invention according to claim 1, the thrust bearing portion interposed between the end surface located on the suction port side of the bearing and the inner bottom surface of the pump housing portion facing the end surface is integrally projected from the shaft. This inexpensive configuration can effectively prevent abnormal noise and uneven wear between the bearing end face and the inner bottom face of the pump housing, thus extending the life of the pump. There is an effect that can be done.

  Further, in the invention according to claim 2, in addition to the effect of the invention according to claim 1, the shaft-side end of the shaft integrated with the thrust bearing portion is connected to the inner bottom surface of the pump housing portion. By sticking to the inner bottom surface so as to be vertical, the width of the gap between the impeller and the inner bottom surface of the pump housing is kept constant, and fluctuations in the amount of refrigerant returning to the suction port side through the gap are suppressed. There is an effect that the pump performance can be stabilized and an effect that the amount of the refrigerant returning to the suction port side by narrowing the gap as much as possible can be suppressed and the pump performance can be improved.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings. FIG. 1 shows an example of a centrifugal pump according to an embodiment of the present invention. This centrifugal pump is used, for example, as a pump for a cooling and circulating device for cooling a heat generating component built in a computer or the like with a liquid, and is used for circulating a refrigerant such as water or antifreeze. In the following description, one of the axial directions of the shaft 23 that serves as the rotation axis of the centrifugal pump will be described as the upper side, and the other side of the opposite side as the lower side.

  The pump case 1 that forms the outer shell of the centrifugal pump of this example includes a case body 2 having a circular recess 4 that opens upward, and an upper end portion of the case body 2 that is attached to the upper end of the case body 2 via a packing 5. The impeller 6 is housed in a space surrounded by the inner surface of the recess 4 and the lid 3.

  The pump storage portion 7 of this example is composed of a case main body 2 and a lid body 3. The inner peripheral surface 7 a and one inner bottom surface 7 b of the pump storage portion 7 are configured by the inner peripheral surface and the bottom surface of the recess 4, and the other inner bottom surface 7 c of the pump storage portion 7 is configured by the lower surface of the lid 3. Yes.

  A suction flow path 8 is formed in the lid 3 of the pump case 1, and one end of the suction flow path 8 communicates with the outside. The other end of the suction channel 8 opens at the center of the inner bottom surface 7 c of the pump storage unit 7 and communicates with the pump storage unit 7. The suction port 9 is configured by the other end opening of the suction channel 8. ing. Note that an external pipe (not shown) is connected to the end of the suction flow path 8 opposite to the suction port 9.

  A discharge channel 10 is formed in the case main body 2 of the pump case 1, and one end of the discharge channel 10 communicates with the outside. The other end of the discharge flow path 10 opens at the upper end of the inner peripheral surface 7a of the pump storage section 7 and communicates with the pump storage section 7, and the discharge opening 11 is configured by the other end opening of the discharge flow path 10 Yes. Note that an external pipe (not shown) is connected to the end of the discharge channel 10 opposite to the discharge port 11.

  A housing recess 14 formed in an annular shape so as to surround the recess 4 is provided on the lower surface of the case body 2, and a cylindrical stator 13 that generates a magnetic field as drive means is housed in the housing recess 14. . A control unit 15 that controls the stator 13 is provided below the housing recess 14, and the stator 13 and the control unit 15 are closed by a lid 16.

  The impeller 6 for sucking and discharging the fluid stored in the pump storage portion 7 is formed using, for example, plastic such as PPS, and the disk-shaped front shroud 17 on the suction port 9 side and the side opposite to the suction port 9 are formed. The rear shroud 18 is welded via a plurality of blades 19 (impellers). A space between the blades 19 and 19 sandwiched between the shrouds 17 and 18 is a fluid passage 20.

  The plurality of blades 19 extend substantially radially from the center side of the rear shroud 18 toward the outer peripheral side. Each blade 19 is curved so as to incline backward with respect to the rotation direction of the impeller 6 from the center side toward the outer peripheral side.

  A bearing insertion hole 38 is formed through the center of the rear shroud 18. The bearing insertion hole 38 is composed of a small-diameter cylindrical portion 21 projecting downward from the center portion of the rear shroud 18. A cylindrical bearing 22 made of baked carbon or molded carbon is inserted into the bearing insertion hole 38. Yes. Inside the bearing 22, a shaft 23 serving as a rotation center of the impeller 6 is rotatably inserted, and the bearing 22 is a sliding bearing in which the impeller 6 moves in the axial direction. The end of the bearing 22 on the suction port 9 side slightly protrudes from the upper surface of the rear shroud 18.

  The shaft 23 is formed in a cylindrical shape using a metal such as stainless steel. The lower end portion of the shaft 23 is fitted and fixed in a fitting hole 24 formed in the center portion of the inner bottom surface 7 b of the pump storage portion 7. Further, a shaft support portion 25 made of a hole that opens downward is formed in a portion that is located in the center of the suction port 9 and that constitutes the inner bottom surface 7 c of the pump storage portion 7. An upper end portion that is an end portion of the shaft 23 on the suction port 9 side is press-fitted and fixed to the shaft support portion 25, and the shaft 23 is supported by the pump case 1 in this state.

  A ring-shaped bearing plate 26 made of ceramic or the like is disposed between the lower end surface of the bearing 22 of the impeller 6 and the inner bottom surface 7b of the pump housing portion 7 facing the bearing 22. The lower end portion of the shaft 23 is rotatably inserted in the central hole of the bearing plate 26 so that the bearing plate 26 receives a thrust load below the impeller 6.

  A thrust bearing portion 32 formed integrally with the shaft 23 is interposed between the upper end surface of the bearing 22 of the impeller 6 and the inner bottom surface 7c of the pump housing portion 7 facing the bearing 22. As will be described later, the thrust bearing portion 32 is adapted to receive a thrust load above the impeller 6 by the thrust bearing portion 32.

  A large-diameter cylindrical portion 27 concentric with the center of the impeller 6 projects downward on the outer peripheral side of the rear shroud 18, and a cylindrical rotor 28 is integrally formed on the outer peripheral side of the large-diameter cylindrical portion 27. It is attached. The rotor 28 is composed of a permanent magnet having magnetic poles alternately formed in the circumferential direction, and is disposed opposite to the stator 13 with a peripheral wall forming the recess 4 interposed therebetween. In the figure, 29 is a water passage provided on the inner peripheral side of the rear shroud 18 so that the fluid between the impeller 6 and the bottom surface of the recess 4 is returned to the fluid passage 20 of the impeller 6.

  At the center side of the front shroud 17 of the impeller 6, a cylindrical suction mouth mouth portion 30 that protrudes toward the suction mouth 9 side of the pump case 1 is provided. The diameter of the inlet mouth portion 30 is formed larger than that of the inlet 9, and the distal end portion of the inlet mouth portion 30 is inserted into an annular recess 31 formed on the inner bottom surface 7 c of the pump storage portion 7 so as to surround the inlet 9. is doing.

  Therefore, in the centrifugal pump of this example having the above-described configuration, when a control current is applied to the stator 13 by the control unit 15, the stator 13 generates a magnetic field, and the rotor 28 is rotationally driven by this magnetic field. When the rotor 28 is rotationally driven, the impeller 6 integrated with the rotor 28 is rotationally driven. As a result, the fluid is sucked from the suction port 9 of the suction flow path 8, is sucked into the fluid passage 20 in the impeller 6 through the suction port mouth portion 30, and is directed in the outer peripheral direction by the plurality of rotating blades 19. A centrifugal force is applied and discharged from the discharge port 11 of the discharge flow path 10.

  Here, in the centrifugal pump of this example, as shown in an enlarged view in FIG. 2, the upper end portion that is the end portion on the suction port 9 side of the shaft 23 into which the bearing 22 of the impeller 6 is rotatably fitted is provided. In this case, a convex thrust bearing portion 32 is provided over the entire circumference by forming a part of the upper end portion with a large diameter. The thrust bearing portion 32 is formed integrally with the shaft 23, and its one end surface 32 a that forms a ring faces the inner bottom surface 7 c of the pump storage portion 7, and the other end surface 32 b that also forms a ring shape is the bearing 22. It is provided so as to face the end surface 22a on the suction port 9 side.

  When the upper end portion of the shaft 23 is press-fitted and fixed to the shaft support portion 25 of the pump storage portion 7, the one end surface 32 a side of the thrust bearing portion 32 is in a region surrounding the shaft support portion 25 of the inner bottom surface 7 c of the pump storage portion 7. The shaft 23 is provided so as to be in contact with the entire surface and to support the shaft 23 perpendicularly to the inner bottom surface 7 c of the pump storage portion 7. In this state, the other end surface 32b side of the thrust bearing portion 32 is in sliding contact with the end surface 22a of the bearing 22 across the entire surface when the impeller 6 is rotationally driven.

  That is, when the centrifugal pump is driven, the vicinity of the suction port 9 of the pump housing portion 7 becomes negative pressure, and the rotationally driven impeller 6 moves toward the suction port 9 in the axial direction of the shaft 23. A thrust bearing portion 32 formed integrally with the shaft 23 is interposed between the end surface 22a on the suction port 9 side of the bearing 22 that rotates integrally with the impeller 6 and the inner bottom surface 7c of the pump storage portion 7, As a result, wear of the end surface 22a of the bearing 22 and the inner bottom surface 7c of the pump storage portion 7 is prevented.

  Moreover, the thrust bearing portion 32 is integral with the shaft 23, and the upper end portion of the shaft 23 is connected to the shaft support portion 25 in a state where the end surface 32 a of the thrust bearing portion 32 is in contact with the entire inner bottom surface 7 c of the pump storage portion 7. Therefore, the thrust bearing 32 is not rattled during operation. Therefore, there is no problem that abnormal noise is generated during operation, and there is no problem that uneven wear occurs between the thrust bearing portion 32 and the bearing 22.

  Further, since the thrust bearing portion 32 is formed integrally with the shaft 23, there is no need to provide another member such as the bearing plate 26, and it is fitted to fit another member such as the bearing plate 26 in a non-rotatable manner. Since it is not necessary to form the joint portion in a D-cut or the like, there is an advantage that it can be provided at a low cost.

  By the way, it is necessary to leave a slight gap 33 between the front shroud 17 of the impeller 6 and the inner bottom surface 7c of the pump housing 7 so that the impeller 6 can rotate. Since the pressure in the vicinity of the suction port 9 is negative, a part of the refrigerant sent out to the outer peripheral side is returned to the suction mouth portion 30 side through the gap 33 (see the arrow in the figure). That is, the gap 33 functions as a return flow path, and there is a problem that the pump performance becomes unstable when the amount of refrigerant returning through the return flow path varies greatly during operation.

  On the other hand, in the centrifugal pump of this example, as described above, the entire end surface 32a of the thrust bearing portion 32 abuts on the inner bottom surface 7c of the pump storage portion 7, and the shaft 23 faces the inner bottom surface 7c of the pump storage portion 7. The end of the shaft 23 on the suction port 9 side is fixed to the inner bottom surface 7c of the pump housing 7 so that the width of the gap 33 forming the return flow path is in operation. Can be kept constant. As a result, the amount of refrigerant returning through the return flow path does not vary greatly during operation, and the pump performance is stabilized. Further, since the impeller 6 stably rotates around the shaft 23 that is fixed perpendicularly to the inner bottom surface 7c of the pump housing portion 7, the width of the gap 33 is made as small as possible so that the suction mouth portion 30 side It is possible to suppress the amount of the refrigerant returning to, and improve the pump performance.

  Note that when the end portion of the shaft 23 on the suction port 9 side is fixed to the inner bottom surface 7c of the pump housing portion 7, the modification of FIG. As shown in FIG. 3, the end portion on the suction port 9 side of the shaft 23 may be integrated with the inner bottom surface 7c side of the pump storage portion 7 by insert molding.

It is sectional drawing which shows the basic composition of the centrifugal pump of this invention. It is a principal part enlarged view same as the above. It is a principal part enlarged view of the modification same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump case 6 Impeller 7 Pump accommodating part 7c Inner bottom face 9 Suction port 11 Discharge port 22 Bearing 22a End surface 23 Shaft 32 Thrust bearing part

Claims (2)

  The pump case is formed with a pump storage portion, and a suction port and a discharge port communicating with the pump storage portion. An impeller having a bearing in the center is stored in the pump storage portion, and the impeller bearing is connected to the pump storage portion. The centrifugal pump is provided with a drive means that is pivotally supported by a shaft provided on the shaft and that rotates the impeller around the shaft, and an end face located on the suction port side of the bearing and a pump storage portion facing the end face. A centrifugal pump characterized in that a thrust bearing portion interposed between an inner bottom surface and a shaft is integrally projected from a shaft.   The end portion on the suction port side of the shaft integrated with the thrust bearing portion is fixed to the inner bottom surface so that the shaft is perpendicular to the inner bottom surface of the pump housing portion. Centrifugal pump.

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