JP6491215B2 - Vertical shaft pump - Google Patents

Description

  The present invention relates to a vertical shaft pump having a slide bearing, and more particularly to a vertical shaft pump that performs an atmospheric operation and a drainage (water flow) operation such as a prior standby operation pump and a pump that performs a management operation under dry conditions.

  In recent years, with the progress of urbanization, the heat island phenomenon has occurred due to the reduction of green spaces, the road surface becoming concrete, and the expansion of asphalt, and so-called guerrilla heavy rains frequently occur in urban areas. A large amount of local rainfall is introduced into the waterway without being absorbed into the ground on concrete and asphalt road surfaces. As a result, a large amount of rainwater flows into the drainage station in a short time.

  In order to prepare for the rapid drainage of a large amount of rainwater caused by such frequent torrential rains, drainage pumps installed in the drainage pump station should have rainwater before reaching the drainage pump station in order to prevent inundation damage due to delays in starting. Pre-standby operation to be started is performed.

  FIG. 1 is a partial schematic diagram of a vertical shaft pump that performs a prior standby operation. The water tank 100 of the drainage station is provided with an impeller 22 at the end of a shaft arranged in the vertical direction, and the impeller 22 is inhaled with air to operate even if the water level of the water tank 100 is below the minimum operating water level LWL. A vertical shaft pump 3 capable of continuing (preceding standby operation) is disposed. This vertical shaft pump 3 is provided with a through hole 5 in the side surface portion of the suction bell 27 on the inlet side of the impeller 22, and an air pipe 6 having an opening 6 a in contact with outside air is attached to the through hole 5. Yes. Thereby, in this vertical shaft pump 3, the supply amount of the air supplied into the vertical shaft pump 3 through the through hole 5 is changed according to the water level, and the drainage amount of the vertical pump 3 is controlled below the minimum operating water level LWL.

  FIG. 2 is a diagram for explaining the operating state of the preceding standby operation. For example, for large city rainwater drainage, a vertical shaft pump is started in advance according to rainfall information or the like regardless of the suction water level (A: air operation). As the water level rises from the low water level, the water level reaches the impeller position, and the vertical shaft pump is operated from the idling operation (air operation) to the agitating operation with the impeller (B: air / water agitation operation), and further through the through hole. Then, the operation proceeds to a full operation (D: steady operation) in which 100% water is discharged through an operation of gradually increasing the amount of water (C: air / water mixing operation) while sucking in air supplied through the water. When the water level drops from the high water level, the operation shifts from the full operation to the operation of gradually reducing the water amount while sucking in the air supplied through the through holes together with the water (C: air-water mixing operation). When the water level reaches near LLWL, the operation shifts to an operation (E: air lock operation) in which water is not sucked and drained. These five characteristic operations are collectively referred to as advance standby operation. The pump start is started from the water level LLLWL lower than the lower end of the casing.

  FIG. 3 is a cross-sectional view showing the entire vertical shaft pump 3 that performs the preceding standby operation shown in FIG. The through hole 5 and the air pipe 6 shown in FIG. 2 are not shown. As shown in FIG. 3, the vertical shaft pump 3 is connected to the discharge elbow 30 that is installed and fixed on the pump installation floor, the casing 29 that is connected to the lower end of the discharge elbow 30, and the lower end of the casing 29. A discharge bowl 28 stored inside, and a suction bell 27 connected to the lower end of the discharge bowl 28 for sucking water are provided.

  Rotating shafts 10, 10 ′ connected to each other by a shaft coupling 26 are arranged at substantially radial center portions of the casing 29, the discharge bowl 28, and the suction bell 27 of the vertical shaft pump 3. The rotary shafts 10 and 10 'are supported by an upper bearing 62 fixed to the casing 29 via a support member and a lower bearing 63 fixed to the discharge bowl 28 via a support member. An impeller 22 for sucking water into the pump is connected to one end side (suction bell 27 side) of the rotary shafts 10 and 10 '. The other end side of the rotary shafts 10 and 10 ′ is connected to a driving machine such as an engine or a motor (not shown) that rotates the impeller 22 through the hole provided in the discharge elbow 30 to the outside of the vertical shaft pump 3.

  A shaft seal 34 such as a floating seal, a gland packing, or a mechanical seal is provided between the rotary shafts 10 and 10 'and a hole provided in the discharge elbow 30, and thereby water handled by the vertical pump 3 is supplied to the vertical pump. 3 is prevented from flowing out.

  The driving machine is installed on land so that maintenance and inspection can be easily performed. The rotation of the driving machine is transmitted to the rotating shafts 10, 10 ', and the impeller 22 can be rotated. The water is sucked from the suction bell 27 by the rotation of the impeller 22, passes through the discharge bowl 28 and the casing 29, and is discharged from the discharge elbow 30.

  The vertical shaft pump 3 shown in FIG. 3 is operated in the atmosphere when the pump is activated. That is, the bearings 62 and 63 are operated under dry conditions without liquid lubrication. Here, the dry condition refers to a condition in which the atmosphere of the bearings 62 and 63 during pump operation is in the air without liquid lubrication, and the dry operation refers to operation under that condition. The bearings 62 and 63 are also operated under drainage conditions in which water has passed through the bearings. Here, the drainage condition refers to a condition in which the atmosphere of the bearings 62 and 63 during the pump operation is in water mixed with foreign matter (slurry) such as earth and sand. It refers to water-mixing operation, full-volume operation, air lock operation, etc. Since the bearings 62 and 63 are used under such conditions, the bearings 62 and 63 have the following problems.

  Slide bearings are used for the bearings 62 and 63. Various materials are used for this slide bearing, but in the case of the vertical shaft pump 3 that performs dry operation, a bearing made of resin or ceramics is used from the viewpoint of dry slidability and reliability during drainage operation. There are many. In this case, the slide bearing is required to withstand frictional heat generation during the dry operation and to be resistant to abrasion due to the slurry in the water during the drain operation. However, these two characteristics often contradict each other, and bearing materials with high wear resistance generally tend to have a high friction coefficient. For this reason, if bearing materials are selected giving priority to wear resistance during drainage operation, frictional heat generation under dry conditions will increase, and if bearing materials with a low friction coefficient are selected to suppress frictional heat generation under dry conditions, The wear amount of the bearing material due to the slurry during operation increases.

  In addition, when using a polymer material such as resin or rubber as a cushioning material used with a slide bearing or a plain bearing, there is an upper limit of the usable temperature determined for each material. Determined by the nature of

  In the slide bearing having the characteristics described above, if the wear resistance of the slide bearing is improved in order to improve the maintenance and management of the slide bearing, the friction coefficient of the bearing slide surface increases, and the friction of the bearing slide surface increases. Because of this, vibration described below may occur.

  In general, when a rotary machine such as the vertical shaft pump 3 is operated, the rotary machine may vibrate due to an unbalanced weight of the rotary body itself or an excitation force that is forced on the rotary body due to a fluid load. However, in addition to this, as a cause of vibration of the rotating machine, there is a force generated in a direction (circumferential direction of the rotating body) perpendicular to the displacement direction (radial direction of the rotating body) due to the swing of the rotating body. This force is called destabilizing force and has the function of canceling the damping action of the rotating body. As a result, if the damping action of the entire rotating body becomes negative due to the destabilizing force, divergent vibration (vibration that gradually increases the swinging) may be caused.

  Here, in the aerial operation such as when the vertical shaft pump 3 is activated, since there is no lubricating fluid in the bearing portion as compared with the underwater operation, the bearing sliding surface has a large friction coefficient. Since this frictional force becomes the above destabilizing force, when a bearing material having a high friction coefficient is used, the destabilizing force becomes large and the rotating shafts 10 and 10 'are divergently swung in the direction opposite to the rotational direction. Will cause excessive vibration.

  Further, when such divergent vibration occurs during dry operation, the bearing surface pressure increases due to the vibration, and the frictional force generated on the bearing sliding surface becomes extremely large. Therefore, there is a possibility that the bearing will malfunction due to thermal expansion or seizure due to a sudden rise in bearing temperature.

  On the other hand, during drainage operation of the vertical shaft pump 3, a liquid film is formed on the sliding surface of the sliding bearing. This liquid film generates a destabilizing force, which may cause a large vibration. This phenomenon occurs in a mechanism similar to a phenomenon called oil whip or oil whirl in a plain bearing lubricated with oil. When this phenomenon occurs, the rotary shafts 10 and 10 'vibrate violently and normal operation is impossible.

  In order to prevent these vibrations, it is necessary to reduce the destabilizing force or improve the stability of the rotary shafts 10 and 10 'by adding damping, which is a cause of the destabilizing force during dry operation. As described above, it is difficult to greatly reduce the coefficient of friction, and due to the structure of the vertical shaft pump 3, it is difficult to give a sufficient damping action to the rotary shafts 10 and 10 '.

  As described above, a sliding bearing for a vertical shaft pump that performs a preliminary standby operation is required to have performances such as wear resistance, heat resistance (low friction), and vibration resistance. As a bearing that simultaneously satisfies these requirements at a high level, the inventors have a first sliding portion on the outer peripheral surface and a second sliding portion on the inner peripheral surface, and are in water and in the atmosphere. A bearing having a rotatable rotating member, a first sliding bearing that supports the first sliding portion on an inner peripheral surface, and a second sliding bearing that supports the second sliding portion on an outer peripheral surface. Has been researched and developed for use in vertical shaft pumps.

  According to the developed bearing, the frictional force acting on the rotating member by sliding with the first sliding bearing at the first sliding portion on the outer peripheral surface, and the second at the second sliding portion on the inner peripheral surface. Since the frictional force acting on the rotating member is offset by sliding with the sliding bearing, the frictional force and liquid can be reduced during dry operation and drainage operation including slurry without sacrificing wear resistance. The vibration due to the destabilizing force due to the film or the like can be reduced, and the frictional force applied to the bearing sliding surface can be reduced, so that the heat generation amount of the sliding bearing can be reduced.

  By the way, the arrangement of the developed bearing is arranged as an upper bearing 62 fixed to the casing 29 via a support member or a lower bearing 63 fixed to the discharge bowl 28 via a support member. As described above, it has been considered by the present inventors that the maintenance is ensured by arranging the bottom bearing 66 below (suction side) below the impeller 22. However, no investigation has been made on the position at which the vibration and friction can be more optimally reduced.

  In addition, pumps have different shapes depending on the required performance, but the degree of vibration and friction is also different, and there is an increasing need to consider where to place the developed bearings. I came.

  The present invention pays attention to the arrangement of the developed bearing, which has been overlooked in the past, and optimally reduces the vibration and friction by arranging the developed bearing regardless of the pump. With the goal.

The unbalanced force of the rotating body is a radial load calculated by (weight of the rotating body [kg]) × (deviation of the center of gravity and rotation center [m]) × (square of rotational angular velocity [rad / s]). expressed. The inventors have pointed out that the frictional force of the sliding part of the bearing, which is a factor of vibration due to friction, is particularly large in a bearing provided in a portion (hereinafter referred to as a load point) where unbalanced force generated in an impeller or the like is large. (Friction force) = (Friction coefficient) x (Radial load)
Based on the relationship. As such, since the radial load increases in the vicinity of a heavy object such as an impeller, the frictional force in the vicinity of the heavy object becomes the largest. In the vertical shaft pump 3, since the driving machine and the impeller are connected by the long rotating shafts 10, 10 ', most of the radial load of the entire rotating body is concentrated on the impeller portion. Therefore, it was concluded that it is most effective to arrange a bearing that cancels the frictional force in the portion where the frictional force is the largest. As a result of intensive studies as described above, the inventors have found the following means.

  In order to achieve the above object, a vertical shaft pump according to an embodiment of the present invention has an object connected to a rotating shaft for rotation, a first sliding portion on an outer peripheral surface, and the first sliding portion on the inner periphery. A first sliding bearing supported by a surface, and a second sliding bearing having a second sliding portion on an inner peripheral surface and supporting the second sliding portion on an outer peripheral surface, At least one of the first sliding portion and the second sliding portion is disposed in proximity to an object that is relatively connected among the rotating objects.

  According to the vertical pump according to another aspect of the present invention, the relatively heavy object is an impeller.

  A vertical shaft pump according to another aspect of the present invention includes a rotating shaft, an impeller connected to the rotating shaft and rotating together with the rotating shaft, a first sliding portion rotating together with the rotating shaft, and the first sliding A first slide bearing having a first support portion that supports the portion on its inner peripheral surface, a second sliding portion that rotates together with the rotating shaft, and the second sliding portion on its outer peripheral surface. A second slide bearing having a second support portion to support, wherein at least one of the first sliding portion and the second sliding portion is provided inside the impeller.

  According to the present invention, in any pump, a bearing that cancels the frictional force is disposed on a rotating body such as an impeller that tends to increase the frictional force of the sliding surface due to an unbalanced force. The frictional force applied to can be effectively reduced. Therefore, vibration and friction can be optimally reduced.

It is the partial external view of the vertical shaft pump which performs a prior | preceding standby operation. It is a figure explaining the driving | running state of a prior | preceding standby driving | operation. It is sectional drawing which shows the whole vertical shaft pump which performs a prior | preceding standby operation. It is a layout view of a conventional bearing of a vertical shaft pump that performs a prior standby operation. FIG. 4 is a detailed view of a part a shown in FIG. 3. It is a modification of the embodiment described in FIG. It is a longitudinal cross-sectional schematic diagram explaining the principle which cancels the frictional force by a 1st slide bearing and a 2nd slide bearing. It is sectional drawing in the XX 'cross section shown in FIG. It is a figure which shows operation | movement of the 1st slide bearing at the time of dry operation, and a 2nd slide bearing. It is a figure which shows operation | movement of the 1st slide bearing at the time of drainage operation, and a 2nd slide bearing.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 10, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 5 is a detailed view of a part a in FIG. 3 and shows a part relating to a state in which the first slide bearing 1 and the second slide bearing 2 are arranged in the vertical direction of the rotary shaft 10 ′. Note that the vertical pump according to the present embodiment has a shape similar to that of the vertical pump shown in FIG.

  As shown in FIG. 3, an inner cylinder 42 is disposed inside the discharge bowl 28 in the vertical shaft pump 3 so as to surround the rotary shaft 10 ′ via a guide vane 41. As shown in FIG. 5, the rotary shaft 10 ′ is supported by a first slide bearing 1 and a second slide bearing 2. The first plain bearing 1 is supported by a support member 43 connected to the inner cylinder 42 inside the inner cylinder 42 shown in FIG.

  As shown in FIG. 5, the first plain bearing 1 includes a first sleeve 31 (first sliding portion) and a first bearing 44 (first support portion). In the first plain bearing 1, the first sleeve 31 is fixed to the outer peripheral side of the rotating shaft 10 '(rotating body) as the sliding portion on the outer peripheral side of the rotating body, and the first sleeve 31 is connected to the rotating shaft 10'. Rotates with rotation. The first bearing 44 that slides on the outer periphery of the first sleeve 31 is supported by the first bearing holder 53 via the first back metal 51 and the first cushioning material 52 as a sliding portion on the inner peripheral side on the fixed side. 43 is fixed.

  The second plain bearing 2 has a second sleeve 37 (second support part) and a second bearing 39 (second sliding part). In the second sliding bearing 2, the second bearing 39 serves as a sliding portion on the inner peripheral side of the rotating body by the second bearing holder 59 (rotating body) via the second back metal 54 and the second buffer material 55. The impeller 22 or a position close to the impeller 22 is fixed to a rotating body (rotating shaft 10 ′, impeller 22, second bearing holder 59, etc.). In other words, the second bearing 39 is fixed to a rotating body such as the second bearing holder 59 located inside the impeller 22 (inside the impeller 22 through which the rotation shaft 10 ′ passes). The second bearing 39 may be fixed to the second bearing holder 59 located inside the impeller 22 as in the illustrated example, or may be directly fixed to the impeller 22 or the rotary shaft 10 ′. The second bearing 39 rotates as the impeller 22 and the like rotate. The second sleeve 37 is fixed to the outer periphery of the fixed sleeve holder 56 connected to the support member 43 as a sliding portion on the outer peripheral side of the fixed side that slides with the inner periphery of the second bearing 39.

  The fixed sleeve holder 56 includes a connection portion 56 a connected to the support member 43 and a cylindrical sleeve support portion 56 b that supports the second sleeve 37. Since the length of the sleeve support portion 56b in the longitudinal direction can be extended to the position of the center of gravity of the impeller 22, the second slide bearing 2 is disposed at a position closest to the position of the center of gravity of the impeller 22. Can do.

  In the vicinity of the fixed sleeve holder 56 and the second bearing holder 59 of the impeller 22, a first water passage hole 57 and a second water passage hole 58 are provided, respectively, between the first sleeve 31 and the first bearing 44 and the second water passage hole 58. Since water is passed between the sleeve 37 and the second bearing 39, smooth sliding is performed. At the same time, accumulation of sediments can be prevented, and air and water around the sliding part can be switched quickly when switching between atmospheric operation and underwater operation. It comes to reduce.

  FIG. 6 is a modification of the embodiment described in FIG. FIG. 6 is a view showing a state in which both the slide bearings 1 and 2 are arranged close to the impeller 22 while the first slide bearing 1 and the second slide bearing 2 are arranged on the same rotation plane of the rotary shaft 10 ′. It is.

  In the first plain bearing 1, the second bearing / sleeve holder 64 connected to the impeller 22 or the rotating body (rotating shaft 10 ′) at a position close to the impeller 22 as a sliding portion on the outer peripheral side of the rotating body. The first sleeve 31 is fixed to the outer peripheral side. The first sleeve 31 rotates with the rotation of the rotation shaft 10 '. In other words, the first sleeve 31 is fixed to a rotating body such as the second bearing / sleeve holder 64 positioned inside the impeller 22. The first sleeve 31 may be fixed to the outer peripheral side of the second bearing / sleeve holder 64 located inside the impeller 22 as in the illustrated example, or directly fixed to the impeller 22 or the rotary shaft 10 ′. May be.

  The first bearing 44 is connected to the support member 43 together with the first back metal 51 and the first cushioning material 52 as a sliding portion on the inner peripheral side of the fixed side that slides with the outer periphery of the first sleeve 31. It is fixed to the inner periphery of the cum fixing sleeve holder 65.

  In the second sliding bearing 2, the second bearing 39 is used as the sliding portion on the inner peripheral side of the rotating body together with the second back metal 54 and the second cushioning material 55 by the second bearing / sleeve holder 64. 22 is fixed to a rotating body (rotating shaft 10 ′ or the like) at a position close to 22. The second bearing 39 rotates as the impeller 22 and the like rotate. In other words, the second bearing 39 is fixed to a rotating body such as the second bearing / sleeve holder 64 located inside the impeller 22. The second bearing 39 may be fixed to the inner peripheral side of the second bearing / sleeve holder 64 located inside the impeller 22 as in the illustrated example, or directly fixed to the impeller 22 or the rotary shaft 10 ′. It may be.

  The second sleeve 37 is fixed to the outer periphery of the first bearing / fixed sleeve holder 65 connected to the support member 43 as a sliding portion on the outer peripheral side of the fixed side that slides with the inner periphery of the second bearing 39.

  In this way, the outer peripheral surface of the second bearing / sleeve holder 64 is the first sliding bearing 1, and the inner peripheral surface of the second bearing / sleeve holder 64 is the second sliding bearing 2. Form.

  The first bearing / fixed sleeve holder 65 includes a connecting portion 65a connected to the support member 43, a cylindrical first bearing holder 53 that supports the first bearing 44 on its inner peripheral surface, and a second sleeve on its outer peripheral surface. And a cylindrical fixed sleeve holder 56 for supporting 37. Since it is possible to process the cylindrical member by extending the length in the longitudinal direction to the position of the center of gravity of the impeller 22, the second slide bearing 2 is disposed at a position closest to the position of the center of gravity of the impeller 22. can do.

  In the vicinity of the first bearing / fixed sleeve holder 65 and the second bearing / sleeve holder 64, a first water passage hole 57 and a second water passage hole 58 are provided, respectively, and water is passed between each sleeve and the bearing. Therefore, smooth sliding is performed. At the same time, accumulation of deposits is prevented, and air and water around the sliding part can be switched quickly when switching between atmospheric operation and underwater operation, so that vibration due to transient conditions of both can be reduced quickly. It has become.

  Next, the first slide bearing and the second slide bearing will be described. FIG. 7 is a schematic vertical cross-sectional view for explaining the principle of canceling the frictional force generated by the first and second sliding bearings. In the illustrated example, a first sleeve 31 (first sliding portion) is provided on the outer periphery of the rotating shaft 10 (10 ′) (rotating body). The material of the first sleeve 31 is practically made of cemented carbide or stainless steel. A hollow cylindrical first bearing 44 (first support portion) is provided on the outer peripheral side of the first sleeve 31. That is, the first sleeve 31 contacts and slides inside the first bearing 44. The material of the first bearing 44 is practically made of a resin material, ceramics, sintered metal, or surface-modified metal. The outer peripheral surface (first sliding portion 46) of the first sleeve 31 faces the inner peripheral surface (sliding surface) of the first bearing 44 via a very narrow first clearance 47, and the first bearing 44 It is comprised so that it may slide with respect to a sliding surface. The outer peripheral portion of the first bearing 44 is fixed to the inner peripheral surface of the substantially cylindrical bearing case 32. The material of the bearing case 32 is practically made of metal or resin.

  A hollow cylindrical second bearing 39 (second support portion) is provided on the outer peripheral surface of the bearing case 32. The material of the second bearing 39 is practically made of a resin material, ceramics, sintered metal, or surface-modified metal. In addition, the material of the 1st bearing 44 and the 2nd bearing 39 has a more preferable same kind material from a viewpoint of the clearance change by the linear expansion coefficient of material.

  A substantially cylindrical sleeve case 38 is fixed to the rotating shaft 10 (10 ′) by fixing means 33a such as a fixing pin or a bolt, and the rotating shaft 10 (10 ′) is connected to the sleeve case 38 (rotating body). It is comprised so that it may rotate with the rotating shaft 10 (10 ') by rotating. A second sleeve 37 (second sliding portion) is provided on the inner peripheral surface of the sleeve case 38, and the inner peripheral surface (second sliding portion 36) of the second sleeve 37 is the outer peripheral surface of the second bearing 39. It is configured to face the (slip surface) through a very narrow second clearance 48 and slide with respect to the slide surface of the second bearing 39. That is, the second sleeve 37 circumscribes and slides outside the second bearing 39. The sleeves 31 and 37 are generally installed on the outer periphery of a shaft member or the like, but in the present application, in order to make the configuration of the bearing unit easy to understand, for the sake of convenience, the sleeves 31 and 37 bear the main bearing material. First and second sliding bearings are used, and the opposed sliding members are referred to as sleeves. In the example shown in FIG. 7, the first back metal 51, the first buffer material 52, the second back metal 54, and the second buffer material 55 shown in FIGS. 5 and 6 are not provided. May be provided.

  The first bearing 44 and the second bearing 39 are fixed to a supporting member 35 connected to a casing such as a pump via a flange portion 32a of the bearing case 32 by a fixing means 33b such as a bolt. In the above example, the first sleeve 31 is held on the outer periphery of the rotating body (rotating shaft 10 (10 ′)), and the non-rotating bearing corresponding to the outer peripheral side of the first sleeve 31 is the first bearing 44. . On the other hand, a second sleeve 37 is provided on the inner circumference of the rotating body (sleeve case 38), and a non-rotating bearing corresponding to the inner circumference side of the second sleeve 37 is a second bearing 39. However, the first bearing 44 may be held on the outer periphery of the rotating body (rotating shaft 10 (10 ′)), and the first sleeve 31 may be provided on the corresponding non-rotating body. Further, in the first sliding bearing 1, the first sleeve 31 is held on the outer periphery of the rotating body, and the corresponding first bearing 44 is on the non-rotating side, so that the second sliding bearing 2 has the inner periphery of the rotating body. It is possible to hold the second bearing 39 in the state where the corresponding second sleeve 37 is on the non-rotating side and vice versa. That is, regardless of the positional relationship between the first bearing 44 and the first sleeve 31 and the positional relationship between the second bearing 39 and the second sleeve 37, the first sliding bearing 1 and the second sleeve The basic principle for offsetting the frictional force caused by the sliding bearing 2 remains unchanged.

  In consideration of the case where the first sliding bearing 1 and the second sliding bearing 2 are used in a drainage pump such as a vertical shaft pump and used in an underwater environment, the sleeve case 38 contains slurry or the like. A water supply port 40 through which water passes through the first clearance 47 and the second clearance 48 is provided. The water that has flowed into the water supply port 40 passes through the first clearance 47 and the second clearance 48 as flow paths. In this way, a flow path for allowing water to pass through the first clearance 47 and the second clearance 48 is formed, and the first clearance 47 and the second clearance 48 also function as a flow path. Water can flow promptly through the first clearance 47 and the second clearance 48 without staying, and the functions of the first slide bearing 1 and the second slide bearing 2 can be exhibited quickly.

  Further, the first bearing 44 and the second bearing 39 support the first sleeve 31 and the second sleeve 37 under dry conditions at the time of starting, and the first sleeve 31 and the second bearing 39 through a very thin liquid film under drainage conditions. Two sleeves 37 are supported. Here, the dry condition refers to a condition in which the atmosphere of the first bearing 44 and the second bearing 39 during operation is in the air without liquid lubrication, and the dry operation refers to operation under those conditions.

  In order to suppress the steady swing of the rotating shaft 10 (10 ′) and to suppress the load applied to the first bearing 44 and the second bearing 39 due to the swing, the diameter clearance dimension (the first clearance 47) The inner diameter of the first bearing 44—the outer diameter of the first sleeve 31) and the diameter clearance dimension of the second clearance 48 (the inner diameter of the second sleeve 37—the outer diameter of the second bearing 39) are respectively the inner diameters of the first bearing 44. It is preferably 1/1000 or more and 1/100 or less and 1/1000 or more and 1/100 or less of the outer diameter of the second bearing 39. When the dimensions of the first clearance 47 and the second clearance 48 are larger than these ranges, the steady swing of the rotary shaft 10 (10 ') becomes large, and the first bearing 44 and the second bearing are rotated by this swing. The load applied to the bearing 39 is also increased, and stable operation may be difficult. Further, when the dimensions of the first clearance 47 and the second clearance 48 are smaller than these ranges, the first clearance 47 and the second clearance 48 are closed by foreign matter, or the first bearing 44 and the second bearing 48 are closed. 39 may be seized due to friction with foreign matter.

  The diameter clearance dimension of the first clearance 47 and the diameter clearance dimension of the second clearance 48 are preferably the same, but the first bearing 44, the second bearing 39, the first sleeve 31, or the second sleeve 37 is made of resin. If these members have elasticity, such as being formed of, the function of the present invention is exhibited even if there is a difference in dimensions. In this case, the ratio of the diameter clearance dimension of the second clearance 48 to the diameter clearance dimension of the first clearance 47 is preferably 0.5 or more and 2.0 or less, more preferably 0.7 or more and 1.3. It is as follows. However, as will be described later, when the first bearing 44, the second bearing 39, the first sleeve 31, or the second sleeve 37 is further fixed via a cushioning material such as rubber (see FIG. 6 etc.) The first bearing 44 and the second bearing 39 can be in contact with the first sleeve 31 and the second sleeve 37 at the same time, even if the dimensions are not in the above-mentioned range due to the deformation of the material, and the function of the present invention is exhibited.

  FIG. 8 is a cross-sectional view taken along the line XX ′ shown in FIG. As shown in the figure, the centers of the outer peripheral surface of the first sleeve 31, the inner peripheral surface of the first bearing 44, the outer peripheral surface of the second bearing 39, and the inner peripheral surface of the second sleeve 37 substantially coincide with the central axis O. Is configured to do. In FIG. 8, the dimensions of the first clearance 47 and the second clearance 48 are shown enlarged for convenience.

FIG. 9 is a diagram illustrating operations of the first slide bearing 1 and the second slide bearing 2 during the dry operation. When the rotating shaft 10 (10 ′) rotates, the first sleeve 31 fixed to the rotating shaft 10 (10 ′) and the second sleeve 37 fixed to the sleeve case 38 also rotate. Under dry conditions, when the outer peripheral surface of the first sleeve 31 contacts the first bearing 44 at the point A, a bearing reaction force _FAN is generated on the rotary shaft 10 (10 ′). This bearing reaction force _{F AN,} frictional force _{F AF} is generated in a direction opposite to the rotating direction of the rotary shaft 10 (10 '), opposite the friction force _{F AF} is the rotational direction in the rotation shaft 10 (10') It becomes a destabilizing force that causes a whirling vibration in the direction.

On the other hand, when the second sleeve 37 contacts the second bearing 39 at the point B, a bearing reaction force _FBN is generated, and this bearing reaction force _FBN is a force in a direction opposite to the frictional force _FAF. A frictional force _FBF is generated. In the system of the rotating shaft 10 (10 '), the frictional force _FAF and the frictional force _FBF are canceled out, so that the rotating shaft 10 (10') can rotate stably. Further, since the load (bearing reaction force) relating to the rotating shaft 10 (10 ') is dispersed at the points A and B, the frictional force applied to the slide bearing is also dispersed. As a result, heat generation due to friction is reduced, and the temperature rise of the bearing during dry operation is suppressed.

FIG. 10 is a diagram illustrating operations of the first slide bearing 1 and the second slide bearing 2 during the drainage operation. The first clearance 47 and the second clearance 48 are filled with water, and the water forms a liquid film 49 and a liquid film 50, respectively, whereby the first slide bearing 1 and the second slide bearing 2 are Functions as a fluid lubricated bearing unit. In this case the liquid film 49, the rotary shaft 10 (10 ') rotating in the circumferential direction of the pressure nonuniformity caused by the As a result, the rotary shaft 10 (10') radially fluid force _{F AR} and the circumferential fluid force F _AT occurs. The circumferential fluid force F _AT becomes destabilizing force that generates vibrations during drainage operation. Incidentally, the circumferential fluid force F _AT is the frictional force F _AF generated by the drying operation is a reverse force.

  Conventionally, in order to prevent unstable vibration due to the liquid film in the vertical rotating shaft, the inner surface of the bearing is formed in a multi-arc shape instead of a perfect circle shape. However, when a bearing made of a resin is used in water containing a large amount of slurry, the inner surface shape of the bearing approaches a perfect circle shape due to wear, and the vibration suppressing effect may be lost.

Here, according to the present bearing unit, in the liquid film 50 in the second clearance 48, the circumferential pressure non-uniformity occurs due to the rotation of the second sleeve 37, and as a result, the rotation shaft 10 (10 ') has a radial direction. A fluid force F _BR and a circumferential fluid force F _BT are generated. At this time, the circumferential fluid force F _AT and the circumferential fluid force F _BT is opposite to each other, the liquid film 49, destabilizing forces due to the liquid film 50 is canceled, the rotary shaft 10 (10 ') is not It can rotate stably without generating vibration due to the stabilizing force.

  As mentioned above, the 1st slide bearing 1 and the 2nd slide bearing 2 are the slide bearings which always slide on a sliding surface and support a rotating shaft in any service operation at the time of dry operation and drainage operation. However, since the frictional force acting on the contact of the first bearing and the contact of the second bearing cancels out, vibration of the rotating shaft due to the destabilizing force can be suppressed and stable rotation of the rotating shaft can be maintained.

  As described above, according to the first slide bearing 1 and the second slide bearing 2 shown in FIG. 7, the first bearing is caused by the swing of the shaft of the rotary shaft 10 (10 ′) during the dry operation. Even if the rotating body (the first sleeve 31 and the second sleeve 37) collides with the 44 and the second bearing 39, the directions of the frictional forces act in opposite directions to cancel each other at the time of the collision. It is possible to suppress the divergence of the swinging of ′) and to prevent vibration due to destabilization. In addition, it is possible to reduce friction caused by this vibration and suppress an increase in bearing temperature.

  Since the first slide bearing 1 and the second slide bearing 2 shown in FIG. 7 have the first bearing 44 and the second bearing 39, the frictional force of the bearing slide surface during the dry operation is dispersed and the bearing slide is dispersed. Heat generation due to surface friction can be suppressed. Thereby, a bearing material having a higher friction coefficient than that of the conventional structure, that is, a bearing material having higher wear resistance can be used, and stable operation can be performed for a long period of time.

  In addition, the first slide bearing 1 and the second slide bearing 2 shown in FIG. 7 hold the first bearing 44 on the inner peripheral surface of the bearing case 32 and hold the second bearing 39 on the outer peripheral surface thereof. The structure can be made compact in the axial direction of the vertical pump.

  The first slide bearing 1 and the second slide bearing 2 shown in FIGS. 5 and 6 can have the same effect as the first slide bearing 1 and the second slide bearing 2 shown in FIG. Further, the first slide bearing 1 and the second slide bearing 2 shown in FIGS. 5 and 6 have a relatively heavy weight of a rotating body such as an impeller that tends to increase the frictional force of the sliding surface due to an unbalanced force. Since the bearing that cancels the frictional force is disposed close to the object, the frictional force applied to the rotating body can be effectively reduced. Therefore, vibration and friction can be optimally reduced.

  By the way, the vertical shaft pump provided with the 1st slide bearing 1 and the 2nd slide bearing 2 which concern on this embodiment is a part (the 1st sleeve 31 and the 2nd sleeve 37) located in the water of the rotating shaft 10 (10 '). ) Is supported only by bearings such as the first bearing 44 and the second bearing 39. That is, a rolling bearing such as a ball bearing or a roller bearing is not suitable for an underwater bearing of a rotating machine that performs drainage operation, and the effect of this embodiment can be achieved by a sliding bearing.

  In the sliding bearing according to the present invention described above, the cushioning material does not necessarily have to be provided on the sleeve and on the opposite side of the sliding surface of each sliding bearing. As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to the above-mentioned embodiment, and may be implemented with a different form within the range of the technical idea.

3 ... Vertical shaft pump 10, 10 '... Rotating shaft 22 ... Impeller 31 ... First sleeve 32 ... Bearing case 37 ... Second sleeve 39 ... Second bearing 44 ... First bearing 53 ... First bearing holder 56 ... Fixed sleeve holder 59 ... Second bearing holder

Claims (3)

A vertical pump,
A rotating object connected to a rotating shaft;
A first sliding bearing having a first sliding portion on the outer peripheral surface and supporting the first sliding portion on the inner peripheral surface, and a second sliding portion on the inner peripheral surface having the second sliding portion A second sliding bearing that supports the sliding portion on the outer peripheral surface, and the first sliding portion and the second sliding member are connected to the rotating shaft connected to the rotating shaft. A vertical shaft pump characterized in that at least one of the sliding portions is disposed close to the vertical shaft pump.   2. The vertical shaft pump according to claim 1, wherein the relatively heavy object is an impeller. A rotation axis;
An impeller connected to the rotating shaft and rotating together with the rotating shaft;
A first sliding bearing having a first sliding portion that rotates together with the rotating shaft, and a first support portion that supports the first sliding portion on an inner peripheral surface thereof;
A second slide bearing having a second sliding portion that rotates together with the rotating shaft, and a second support portion that supports the second sliding portion on its outer peripheral surface,
The vertical shaft pump, wherein at least one of the first sliding portion and the second sliding portion is provided inside the impeller.

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