Pre-emptive standby pump

Abstract

To restrain a temperature rise of a bearing in a preceding standby pump to extend its life.SOLUTION: A preceding standby pump comprises a rotating shaft 2 in which an impeller is fixed to a lower end part, and a sliding bearing device 5 rotatably supporting the rotating shaft 2. The sliding bearing device 5 comprises a bearing 9 arranged outside the rotating shaft 2 in a radial direction, back metal 13 arranged on an outer peripheral surface of the bearing 9, a plurality of elastic bodies 15 arranged with gaps 18 in a circumferential direction on an outer peripheral surface of the back metal 13, and a bearing support 14 arranged on outer peripheral surfaces of the plurality of elastic bodies 15.SELECTED DRAWING: Figure 2B

Description

Technical Field

[0001] The present invention relates to a pre-waiting pump, and particularly to a pre-waiting pump that performs standby operation in a lubrication-free state.

Background Art

[0002] In recent years, with the rapid urbanization, the inflow of rainwater into urban drainage airports during heavy rain has become large and rapid, increasing the risk of urban floods. To avoid such problems, a vertical pump that can quickly drain water even in an emergency is required. Therefore, there is an increasing demand for a pre-waiting pump that idles the pump in advance before the rainwater flows into the drainage airport and immediately performs drainage operation when the rainwater flows in.

[0003] The bearing in this pre-waiting pump supports the rotating shaft in an environment where dry sliding during idling operation and water lubrication sliding including foreign matters during drainage operation are repeatedly performed. Conventionally, even during idling operation, an external water injection device was used to maintain a water lubricated state to prevent the bearing from burning out. However, from the viewpoints of cost and maintainability, it is currently the mainstream to use a non-water injection bearing without using an external water injection device even during idling operation.

[0004] The non-water injection bearing includes a sleeve installed to cover the rotating shaft, a cylindrical bearing that supports the rotating shaft and the sleeve at a certain interval, and a bearing housing that supports the bearing. Also, in the non-water injection bearing, a high-strength material (such as cemented carbide) is mainly used for the sleeve, and a material with good slidability (such as resin) is mainly used for the bearing, and it can withstand dry sliding and foreign matter wear for a long time.

[0005] However, in unlubricated sliding, excessive heat generation can cause the bearing to burn out, or thermal expansion of the sleeve and bearing can eliminate the clearance, leading to contact between the sleeve and bearing. Furthermore, imbalance in the rotating shaft or misalignment during assembly can cause partial sliding (uneven contact) between the sleeve and bearing, potentially leading to a localized temperature rise in the circumferential direction of the rotating shaft. In this case, the localized temperature rise can cause the rotating shaft to bend, resulting in problems such as increased vibration and bearing load.

[0006] Conventionally, an example of a pre-operation standby pump using this type of sliding bearing is described in Patent Document 1. Paragraphs 0018 and 0019 of Patent Document 1 state that "The sliding bearing device 11 is configured as follows. As shown in Figures 2 to 4 (of the same publication), the sliding bearing device 11 has a bearing body 15 that rotatably holds a rotating shaft 4, and a cylindrical metal shell 16 arranged radially outside the bearing body 15. The bearing body 15 is fitted into the shell 16, and a cylindrical cushioning member 17 is provided between the bearing body 15 and the shell 16. The bearing body 15 is composed of a cylindrical metal holder 19 and a plurality of bearing-side sliding contact members 20 (sliding contact members) that slide against the outer circumferential surface of the axial-side sliding contact portion 4c of the rotating shaft 4." Figure 5 As shown in Figure 6, the retainer 19 is provided with spigot portions 21 and 22 (fitting portions) on both end faces 19a and 19b in the direction of the axis 7 of the rotating shaft 4. Multiple grooves 23 are formed on the inner circumferential surface of the retainer 19 at predetermined intervals in the circumferential direction A, penetrating the above-mentioned end faces 19a and 19b. As shown in Figure 7, each groove 23 is formed in a concave shape with a cross section perpendicular to the direction of the axis 7 having a certain width. The bearing-side sliding contact member 20 is fitted into the groove 23 and bonded to the groove 23 with adhesive. The inner end of the bearing-side sliding contact member 20 in the radial direction B protrudes from the inner circumferential surface of the retainer 19 toward the axis 7. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2007-263185 [Overview of the project] [Problems that the invention aims to solve]

[0008] As described in paragraph 0028, the sliding bearing device in Patent Document 1 uses a diamond sintered body for the hardened layer 32 of the bearing-side sliding contact member 20 (sliding contact member). However, even when resin is used, heat is generated due to sliding friction.

[0009] However, in the sliding bearing device of Patent Document 1, the bearing body 15 and the shell 16 are cylindrical, and the cushioning member 17 sandwiched between them is also cylindrical, so the heat dissipation effect in the heat conduction path to the shell 16 is small.

[0010] Therefore, in the structure of the sliding bearing device described in Patent Document 1, the temperature of the bearing-side sliding contact member (bearing) tends to rise, accelerating wear.

[0011] The objective of this invention is to suppress the temperature rise of the bearings in the standby pump and extend their lifespan. [Means for solving the problem]

[0012] To achieve the above objective, the pre-standby pump according to the present invention comprises a rotating shaft with an impeller fixed to its lower end, and a sliding bearing device that rotatably supports the rotating shaft, wherein the sliding bearing device comprises a bearing disposed radially outward from the rotating shaft, a bearing retaining member disposed on the outer circumferential surface of the bearing, and on the outer circumferential surface of the bearing retaining member in a circumferential direction , penetrating in a straight line in the axial direction It comprises a plurality of elastic bodies arranged with gaps between them, and elastic body holding members arranged on the outer circumferential surfaces of the plurality of elastic bodies. Through holes are provided directly above and below both sides of the gap in the axial direction, and the elastic body has an equal radial thickness at the central contact point in the axial direction of the rotating shaft, and the radial thickness gradually increases toward both ends of the bearing in the axial direction of the rotating shaft. . [Effects of the Invention]

[0013] According to the present invention, the temperature rise of the bearings in the standby pump can be suppressed, thereby extending their lifespan. [Brief explanation of the drawing]

[0014] [Figure 1] It is a schematic longitudinal sectional view of a pre-waiting pump according to an embodiment of the present invention. [Figure 2A] It is a longitudinal sectional view showing a sliding bearing device of a pre-waiting pump according to the first embodiment. [Figure 2B] It is a horizontal sectional view taken along line IIB-IIB in FIG. 2A. [Figure 2C] It is a schematic perspective view for explaining the temperature rise in the sliding bearing device of the pre-waiting pump according to the first embodiment. [Figure 2D] It is a horizontal sectional view passing through the abutting portion in FIG. 2C. [Figure 2E] It is a perspective view showing the elastic body in FIG. 2A. [Figure 3A] It is a longitudinal sectional view showing a sliding bearing device of a pre-waiting pump according to the second embodiment. [Figure 3B] It is a top view of the sliding bearing device in FIG. 3A. [Figure 4A] It is a schematic perspective view showing the sliding bearing device of a conventional pre-waiting pump. [Figure 4B] It is a schematic perspective view for explaining the temperature rise in the sliding bearing device of a conventional pre-waiting pump. [Figure 4C] It is a horizontal sectional view passing through the abutting portion in FIG. 4B.

Mode for Carrying Out the Invention

[0015] Embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings shown below, the same members or corresponding members are denoted by the same reference numerals, and duplicate explanations are omitted as appropriate. In addition, the sizes and shapes of the members may be schematically represented in a deformed or exaggerated manner for the convenience of explanation.

[0016] 《First Embodiment》 Referring to FIGS. 1, 2A to 2D, and 4A to 4C, a thrust bearing device 5 (a general term for 5a and 5b) according to the first embodiment and a pre-running standby pump 1 using the same will be described. FIG. 1 shows a schematic overall configuration of a pre-running standby pump 1 according to an embodiment of the present invention. FIG. 2A is a longitudinal sectional view showing the structure of the thrust bearing device 5 according to the first embodiment. FIG. 2B is a horizontal sectional view taken along line IIB-IIB in FIG. 2A. FIGS. 2C and 2D are schematic diagrams for explaining the effects of the present embodiment. FIGS. 4A to 4C are schematic diagrams for explaining problems in the thrust bearing device of a conventional pre-running standby pump, shown to facilitate understanding of the operation and effects of the present invention.

[0017] First, the pre-running standby pump 1 to which the present invention is applied will be described using FIG. 1. As shown in FIG. 1, the pre-running standby pump 1 is a vertical pump having a rotating shaft (main shaft) 2 that extends and rotates in the vertical direction. An impeller 3 is fixed to the lower end of the rotating shaft 2.

[0018] Further, a pump casing 4 extends from below the impeller 3 to cover the outer peripheral portion of the impeller 3 and further upward. The pump casing 4 is formed in a substantially cylindrical shape except for the portion of the impeller 3, and the rotating shaft 2 passes through the central portion. The inside of the pump casing 4 forms a water-lifting flow path. [[ID=??]]

[0019] The rotating shaft 2 passing through the inside of the pump casing 4 is rotatably supported by the thrust bearing device 5 at a plurality of locations in the vertical direction (two locations in FIG. 1). The thrust bearing device 5 is used as a non-injection bearing that does not use an external water injection device even during idling operation.

[0020] In the pre-running standby pump 1 shown in FIG. 1, one thrust bearing device 5a is provided in the vicinity of the impeller 3. Further, below the floor surface 20 which is the installation surface of the pre-running standby pump 1, the other thrust bearing device 5b is installed in the middle of the rotating shaft 2 that is connected to the drive motor 6 for driving the pre-running standby pump 1 via a coupling 7. It should be noted that there is an unclear tag "??" in the original text at line 13 which is maintained as is in the translation. If this is an error in the original, it may need to be corrected in the source material for a more accurate translation.

[0021] In other words, the standby pump 1 has a rotating shaft 2 with an impeller 3 at one end (lower end) and a drive motor 6 at the other end (upper end), a pump casing 4 that encloses the impeller 3 and the rotating shaft 2 and becomes a fluid (water) passage when the standby pump 1 is driven, and a sliding bearing device 5 that rotatably supports the rotating shaft 2 in the pump casing 4.

[0022] Next, using Figures 4A to 4C, the problems of a conventional sliding bearing device of a pre-standby pump, which is a comparative example of this embodiment, will be explained. Figure 4A is a schematic perspective view of a sliding bearing device provided in a conventional pre-standby pump. As shown in Figure 4A, the sliding bearing device comprises a bearing 9 arranged radially outward from the rotating shaft 2 and a cylindrical bearing housing (not shown) that holds the bearing 9. A sleeve (sliding layer) 8 is provided on the outer circumferential surface of the rotating shaft 2 so as to cover the outer circumferential surface of the rotating shaft 2. The bearing 9 is cylindrical and is arranged radially at a certain distance from the sleeve 8, supporting the rotating shaft 2 on which the sleeve 8 is installed. The bearing housing (not shown) is cylindrical and holds the bearing 9. The rotating shaft 2 rotates as the shaft-side sliding surface 11, which is the outer circumferential surface of the sleeve 8, and the inner circumferential surface of the bearing 9, which is the sliding member, slide against each other. Note that in Figure 4A, the radial distance between the sleeve 8 and the bearing 9 is depicted as larger than it actually is for illustrative purposes (the same applies to Figures 4B, 2A-2C, 3A, and 3B).

[0023] As described above, there is a certain gap between the sleeve 8 and the bearing 9, so the sleeve 8 may make uneven contact with the bearing 9. If this uneven contact continues, the sleeve 8 will heat up locally, as shown in Figure 4B, around the uneven contact portion 12 between the sleeve 8 and the bearing 9.

[0024] As shown in Figure 4C, localized heat generated around the contact point 12 of the sleeve 8 is transferred to the rotating shaft 2, resulting in a circumferential temperature distribution on both the sleeve 8 and the rotating shaft 2. In Figures 4B and 4C, darker areas indicate higher temperatures (the same applies to Figures 2C and 2D). As a result, as shown in Figure 4B, the rotating shaft 2 may bend due to the difference in thermal expansion. This can lead to excessive vibration of the rotating body, including the rotating shaft 2.

[0025] Therefore, in the sliding bearing device 5 of this embodiment, as shown in Figures 2A and 2B, an elastic body 15 is provided between the back metal 13 and the bearing support 14. Multiple elastic bodies 15 are arranged on the outer circumferential surface of the back metal 13 with a gap 18 in the circumferential direction. The elastic bodies 15 are made of rubber, for example. The back metal 13 is positioned on the outer circumferential surface of the bearing 9 and functions as a bearing retaining member that holds the bearing 9. The bearing 9 is made of resin, for example. The bearing support 14 is positioned on the outer circumferential surfaces of the multiple elastic bodies 15 and functions as an elastic body retaining member that holds the elastic bodies 15. The bearing support 14 is fixed to the pump casing 4 via a support member.

[0026] In this configuration, multiple elastic bodies 15 are arranged on the outer circumferential surface of the back metal 13 that holds the bearing 9 with gaps 18 in the circumferential direction, thereby improving the heat dissipation of the sliding member, the bearing 9. As a result, the temperature rise of the bearing 9 can be suppressed. This reduces the progression of wear on the bearing 9, extending its lifespan. In other words, according to this embodiment, the temperature rise of the bearing 9 in the standby pump 1 can be suppressed, thereby extending its lifespan. Furthermore, as shown in Figures 2C and 2D, in this embodiment, the temperature near the contact point 12 between the sleeve 8 and the rotating shaft 2 is lower than in the conventional example shown in Figures 4B and 4C. As a result, bending of the rotating shaft 2 due to the difference in thermal expansion is suppressed, and thus vibration and increased bearing load are also suppressed.

[0027] Furthermore, in this embodiment, as shown in Figure 2E, the elastic body 15 has a structure in which its radial thickness changes depending on its position in the axial direction of the rotating shaft 2, and the elastic body 15 becomes thicker towards the upper and lower ends of the bearing 9. In other words, the elastic body 15 has a greater radial thickness at both ends (upper and lower ends) in the axial direction of the rotating shaft 2 than at the center. This reduces the surface pressure at the upper and lower ends of the bearing 9 due to uneven contact between the sleeve 8 and the bearing 9, and equalizes the surface pressure of the bearing 9.

[0028] By reducing the surface pressure at the axial end of the bearing 9 and averaging the surface pressure of the bearing 9, the amount of heat generated by the sliding between the sleeve 8 and the bearing 9, which is proportional to the surface pressure, can be reduced. Therefore, the local temperature rise of the bearing 9 can be further suppressed.

[0029] Since the amount of wear on the bearing 9 is proportional to the surface pressure, reducing the surface pressure at the axial end of the bearing 9 and averaging the surface pressure of the bearing 9 can further suppress localized wear on the bearing 9.

[0030] 《Second Embodiment》 Next, the sliding bearing device 5 of the second embodiment will be described with reference to Figures 3A and 3B. Figure 3A is a vertical cross-sectional view showing the structure of the sliding bearing device 5 of the second embodiment, and corresponds to Figure 2A of the first embodiment. Figure 3A is also a horizontal cross-sectional view along the line IIIA-IIIA in Figure 3B. Figure 3B is a top view of the sliding bearing device 5 in Figure 3A. Descriptions of components common to the first embodiment will be omitted as appropriate.

[0031] As shown in Figure 3A, the sliding bearing device 5 of this embodiment includes a pair of holders 16a and 16b, respectively, arranged on both end faces of the back metal 13 and bearing support 14 in the axial direction of the rotating shaft 2. The pair of holders 16a and 16b are plate-shaped and sandwich the back metal 13 and bearing support 14 from above and below. Through holes 17a and 17b are formed in the pair of holders 16a and 16b, respectively, which penetrate through the axial direction of the rotating shaft 2. In this configuration, heat escapes from the inside of the portion sandwiched between the pair of holders 16a and 16b through the through holes 17a and 17b, thereby improving the heat dissipation of the bearing 9, which is a sliding member.

[0032] Furthermore, in this embodiment, the through holes 17a and 17b are configured to allow air to pass through the gap 18 between two adjacent elastic bodies 15. Specifically, the through holes 17a and 17b are provided at positions corresponding to the top and bottom (both sides in the axial direction) of the gap 18.

[0033] In this configuration, when heat is generated due to the sliding of the sleeve 8 and bearing 9 during standby operation (idle operation), the air in the gap 18 between the two adjacent elastic bodies 15 is heated by the heat generated by the sliding of the sleeve 8 and bearing 9. The air in the gap 18 is then discharged through the through hole 17a by the rising airflow generated by the heating. In addition, after the air has escaped to the outside through the through hole 17a of the holder 16a, air from below the sliding bearing device 5 enters the gap 18 by passing through the through hole 17b of the holder 16b.

[0034] Therefore, according to this embodiment, when heat is generated due to the sliding of the sleeve 8 and the bearing 9 during standby operation (idle operation), the temperature rise of the bearing 9 can be further suppressed by heat dissipation through the circulation of air.

[0035] According to the embodiments described above, in a standby pump that operates in a non-lubricated state, it is possible to realize a sliding bearing device 5 that can stably support the rotating shaft 2 even during standby operation (idle operation), and a standby pump 1 using the same.

[0036] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0037] For example, the elastic body 15 may have holes or grooves through which air can pass. In this case, the through holes 17a and 17b are configured to allow air to pass through the holes or grooves of the elastic body 15. Specifically, the through holes 17a and 17b are provided at positions corresponding to the top and bottom (both sides in the axial direction) of the holes or grooves of the elastic body 15, respectively. The holes or grooves of the elastic body 15 are formed, for example, parallel to the axial direction of the rotation axis 2, but are not limited to this, and may be inclined or curved. Also, the holes of the elastic body 15 may be porous. The grooves of the elastic body 15 may be formed by providing, for example, fins on the surface of the elastic body 15. In this configuration, the heat dissipation of the elastic body 15 is improved, which makes it possible to further suppress the temperature rise of the bearing 9.

[0038] Furthermore, the sliding bearing device 5 used in the standby pump 1 may be located in one place or in two or more places, depending on the length of the rotating shaft 2, etc.

[0039] Furthermore, while the above-described embodiment described the case in which the pre-standby pump 1 is applied to a mixed-flow pump in which the flow discharged from the impeller 3 lies in a conical plane with the rotating shaft 2 as its axis, the invention is not limited to this. The pre-standby pump 1 of the present invention is also applicable to an axial-flow pump in which the flow discharged from the impeller 3 lies in a cylindrical plane concentric with the rotating shaft 2. [Explanation of Symbols]

[0040] 1. Pre-emptive standby pump 5,5a,5b Plain bearing device 2 rotation axes 3-Paddle Wheel 8 sleeves 9 bearings 13. Back metal (bearing retaining member) 14. Bearing support (elastic body retaining member) 15 Elastic body 16a, 16b holder 17a,17b through hole 18 gaps

Claims

1. A rotating shaft with an impeller fixed to its lower end, The system includes a sliding bearing device that rotatably supports the aforementioned rotating shaft, The aforementioned sliding bearing device is A bearing positioned radially outward from the aforementioned rotating shaft, A bearing retaining member is disposed on the outer circumferential surface of the bearing, Multiple elastic bodies are arranged on the outer surface of the bearing retaining member with gaps extending circumferentially and linearly through it in the axial direction, The system comprises elastic body holding members arranged on the outer circumferential surfaces of a plurality of elastic bodies, Through holes are provided directly above and directly below the gap on both sides in the axial direction. The elastic body is The radial thickness of the contact portion at the center of the rotating shaft in the axial direction is equal, and the radial thickness gradually increases toward both ends of the bearing in the axial direction of the rotating shaft. A pre-emptive standby pump characterized by the following features.

2. The bearing retaining member and the elastic body retaining member are each provided with a pair of holders arranged on both end faces in the axial direction of the rotating shaft, The preceding standby pump according to claim 1, characterized in that the holder has the through hole that penetrates in the axial direction.

3. The preceding standby pump according to claim 2, characterized in that the through-hole allows air passing through the gap.

4. The elastic body has holes or grooves formed therein through which air passes. The preceding standby pump according to claim 2, characterized in that the through hole allows air passing through the hole or groove.

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