Pumping device

Abstract

In a pump system equipped with an inducer, the rotor dynamics are improved without increasing the overall length of the pump system. [Solution] The pump device 1 according to the present invention comprises a motor 3, a rotating shaft 4 that rotates by the drive of the motor, impellers 61 and 62 attached to the rotating shaft that suck in and discharge the liquid to be handled, a first bearing 51 disposed between the motor and the impeller and rotatably supports the rotating shaft, an inducer 7 disposed upstream of the flow of the liquid to be handled from the impeller, a second bearing 8 that rotatably supports the inducer, and a pump housing 2 that houses the impeller, inducer and second bearing. The inducer comprises inducer blades 72 that rotate in accordance with the rotation of the rotating shaft, and a cylindrical shroud 71 that houses the inducer blades. The shroud has a cylindrical outer surface 71a. The second bearing supports the outer surface of the shroud.

Description

Technical Field

[0001] The present invention relates to a pump device.

Background Art

[0002] A pump device includes a rotor, a rotating shaft, a pair of bearings, and an impeller. The rotor rotates the rotating shaft, and via the rotating shaft, rotates the impeller. In the axial direction of the rotating shaft, the pair of bearings are arranged on both sides of the rotor and rotatably support the rotating shaft. In the axial direction, one side of the rotating shaft protrudes on one side from the bearing, and an impeller is attached to the end thereof. Such a structure in which the impeller is not arranged between the pair of bearings (so-called overhang structure) is widely used in pump devices (see, for example, Patent Document 1).

[0003] The impeller is a heavy object. Therefore, in a centrifugal pump adopting an overhang structure, rotor dynamics are likely to deteriorate. In particular, when an inducer is attached upstream of the impeller, when a plurality of impellers are attached to the rotating shaft (in the case of a multi-stage structure), or when the rotating shaft rotates at high speed, the deterioration of rotor dynamics becomes significant. Patent Documents 2 and 3 disclose technologies for suppressing the deterioration of rotor dynamics (that is, technologies for improving rotor dynamics).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology disclosed in Patent Document 2, bearings are arranged between multiple impellers in a multi-stage centrifugal pump. In the technology disclosed in Patent Document 3, bearings are arranged on both sides of multiple impellers in a multi-stage centrifugal pump. In these technologies, rotor dynamics are improved compared to pump devices with an overhang structure. However, in these technologies, the bearings and impellers are arranged side by side in the axial direction. Therefore, the overall length of the centrifugal pump increases, and its size may not meet the specifications.

[0006] The present invention aims to improve rotor dynamics in a pump system equipped with an inducer without increasing the overall length of the pump system. [Means for solving the problem]

[0007] A pump device in one embodiment of the present invention comprises a motor, a rotating shaft that rotates by the drive of the motor, an impeller attached to the rotating shaft for sucking in and discharging a liquid to be handled, a first bearing disposed between the motor and the impeller and rotatably supporting the rotating shaft, an inducer disposed upstream of the flow of the liquid to be handled from the impeller, a second bearing rotatably supporting the inducer, and a pump housing that houses the impeller, the inducer and the second bearing, wherein in the axial direction of the rotating shaft, the direction in which the inducer is positioned relative to the impeller is the first direction, and the direction in which the impeller is positioned relative to the inducer is the second direction, the inducer comprises inducer blades that rotate in accordance with the rotation of the rotating shaft, and a cylindrical shroud housing the inducer blades, the shroud comprises a cylindrical outer surface, and the second bearing supports the outer surface of the shroud. [Effects of the Invention]

[0008] The present invention improves rotor dynamics in a pump system equipped with an inducer without increasing the overall length of the pump system. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of a pump device showing an embodiment of the pump device according to the present invention. [Figure 2] This is a partially enlarged cross-sectional view of part A in Figure 1 of the pump device described above. [Figure 3] This is a partially enlarged schematic cross-sectional view of part B in Figure 2 of the pump device described above. [Figure 4] This is a schematic perspective view of the inducer in the pump device described above. [Figure 5] This is a schematic front view of the inducer shown above. [Figure 6] This is a partially enlarged schematic diagram of the inducer, showing the location of the through-hole opening in the inducer described above. [Figure 7] This is a partially enlarged schematic diagram of the inducer, showing the location of another opening in the through-hole of the inducer described above. [Figure 8] This is a schematic cross-sectional view showing the flow of the liquid being handled in the suction port of the pump device when the pump device is in operation. [Figure 9] This is the result of a simulation analysis of the rotor dynamics of the pump device described above. [Figure 10] Figure 9 shows the Campbell diagram of the pump system used in the simulation. [Figure 11] These are partially enlarged schematic cross-sectional views of the pump device in each modified example, where (a) shows the pump device in the first modified example, (b) shows the pump device in the second modified example, (c) shows the pump device in the third modified example, (d) shows the pump device in the fourth modified example, and (e) shows the pump device in the fifth modified example. [Modes for carrying out the invention]

[0010] Embodiments of the pump device according to the present invention will be described below. In the following description, the respective drawings are referred to as appropriate. In each drawing, the same members and elements are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensional ratios of the respective elements may be exaggerated for convenience of explanation and are not limited to the ratios shown in each drawing.

[0011] ●Pump device● ●Configuration of the pump device FIG. 1 is a schematic cross-sectional view of a pump device showing an embodiment of the pump device according to the present invention. The figure shows a longitudinal cross-section of the pump device 1 cut along a vertical plane passing through the axis center line of the rotating shaft 4 (described later). In the figure, some configurations are shown non-sectionally for convenience of explanation.

[0012] The pump device 1 sucks and discharges (delivers) the liquid to be handled. The pump device 1 is, for example, a centrifugal pump. The pump device 1 includes a housing 2, a motor 3, a rotating shaft 4, two bearings 51, 52, two impellers 61, 62, an inducer 7, and an inducer bearing 8.

[0013] The "liquid to be handled" is the liquid handled (delivered) by the pump device 1. The liquid to be handled is, for example, a liquid fuel.

[0014] In the following description, the "forward direction" is the direction in which the impellers 61, 62 are located with respect to the motor 3, and the "backward direction" is the direction in which the motor 3 is located with respect to the impellers 61, 62. The "axial direction" is the direction along the axis center line of the rotating shaft 4 (front-back direction), the "radial direction" is the radial direction of the rotating shaft 4, and the "circumferential direction" is the circumferential direction of the rotating shaft 4. The "upstream side" is the upstream side in the flow of the liquid to be handled in the housing 2, and the "downstream side" is the downstream side in the flow of the liquid to be handled in the housing 2. The "rotation direction RD (see FIG. 4)" is the direction in which the rotating shaft 4 rotates, and in the present embodiment, it is the counterclockwise direction when viewed from the forward direction. The forward direction is an example of the first direction in the present invention, and the backward direction is an example of the second direction in the present invention.

[0015] The housing 2 houses the motor 3, the rotating shaft 4, the bearings 51 and 52, the impellers 61 and 62, the inducer 7, and the inducer bearing 8. The housing 2 includes two pump chambers 21 and 22, a suction hole 23, a motor chamber 24, a suction pipe portion 25, a discharge pipe portion 26, and a connecting flow path 27. The housing 2 is an example of the pump housing in the present invention.

[0016] FIG. 2 is a partially enlarged cross-sectional view of part A in FIG. 1 of the pump device 1. In the following description, FIG. 1 is appropriately referred to together with FIG. 2.

[0017] The pump chamber 21 houses the impeller 61. The pump chamber 21 has a front inner surface 21a. The front inner surface 21a is the surface of the inner surface of the pump chamber 21 that faces backward. The front inner surface 21a is disposed forward of the front shroud 61b (described later) of the impeller 61 and faces the front shroud 61b. The shape of the front inner surface 21a is a curved surface that is recessed in a substantially frustoconical shape forward so as to follow the shape of the front shroud 61b.

[0018] The pump chamber 22 houses the impeller 62. Since the configuration of the pump chamber 22 is common to that of the pump chamber 21, a detailed description thereof is omitted. The pump chamber 22 is disposed rearward of the pump chamber 21.

[0019] The suction hole 23 guides the handling liquid to the impeller 61 and the inducer 7. The suction hole 23 is disposed at the front end portion of the housing 2. The suction hole 23 is disposed forward of the pump chamber 21 and adjacent to the pump chamber 21 and communicates with the pump chamber 21. The shape of the suction hole 23 is a three-stage cylindrical shape along the axial direction. The suction hole 23 includes a large-diameter portion 23a, a medium-diameter portion 23b, a small-diameter portion 23c, a first-stage portion 23d, a second-stage portion 23e, a bypass flow path 23f, and a female screw surface 23j.

[0020] The inner diameter of the large-diameter portion 23a is larger than the inner diameter of the medium-diameter portion 23b, and the inner diameter of the medium-diameter portion 23b is larger than the inner diameter of the small-diameter portion 23c. In the axial direction, the medium-diameter portion 23b is located in front of the large-diameter portion 23a and adjacent to the large-diameter portion 23a. In the axial direction, the small-diameter portion 23c is located in front of the medium-diameter portion 23b and adjacent to the medium-diameter portion 23b. The first step portion 23d is located between the large-diameter portion 23a and the medium-diameter portion 23b and is a surface facing the rear. The second step portion 23e is located between the medium-diameter portion 23b and the small-diameter portion 23c and is a surface facing the rear. In a rearward view, the shape of the first step portion 23d is ring-shaped. The shape of the second step portion 23e is a planar shape parallel to the vertical direction and is ring-shaped in a rearward view. The second step portion 23e is an example of an opposing surface in the present invention. An internal threaded surface 23j is located on the inner circumferential surface of the large-diameter portion 23a.

[0021] The bypass channel 23f is a channel that returns the handling fluid that has flowed from the impeller 61 into the first cylindrical space S2 (described later) to the main flow of the handling fluid F0 (see Figure 8; the same applies hereinafter) flowing through the small diameter section 23c. The shape of the bypass channel 23f is, for example, tubular. The bypass channel 23f is provided with a channel inlet 23g and a channel outlet 23h. The channel inlet 23g opens into the medium diameter section 23b and the second stage section 23e. The channel outlet 23h opens into the small diameter section 23c. Of the bypass channel 23f, the front end portion 23i on the channel outlet 23h side is inclined more towards the rear than radially. The front end portion 23i is an example of an open end portion in the present invention.

[0022] In this invention, the number of bypass channels 23f can be set as appropriate and is not limited to "1".

[0023] The motor room 24 houses the motor 3, a portion of the rotating shaft 4, and bearings 51 and 52. The motor room 24 is partitioned by the rear half of the housing 2.

[0024] The front end of the housing 2 extends cylindrically forward so as to be coaxial with the rotation axis 4, forming a suction pipe section 25. The suction pipe section 25 is composed of a front half of a large diameter section 23a, a medium diameter section 23b, a small diameter section 23c, a first stage section 23d, and a second stage section 23e.

[0025] A portion of the housing 2 located radially outward from the impeller 62 extends tangentially (upward) to the impeller 62 in an axial view, forming a discharge pipe section 26 for discharging the liquid being handled from the pump chamber 22.

[0026] The connecting passage 27 is a passage that connects the pump chamber 21 and the pump chamber 22, and guides the liquid being handled discharged from the impeller 61 from the pump chamber 21 to the pump chamber 22. The connecting passage 27 is formed, for example, from a part of the housing 2.

[0027] Motor 3 is a known motor comprising a rotor attached to a rotating shaft 4 and a stator that rotates the rotor.

[0028] The rotating shaft 4 rotates due to the drive (rotation) of the motor 3, and transmits rotational power to the impellers 61, 62 and inducer 7. The rotating shaft 4 is cylindrical in shape. The rotating shaft 4 is attached to the motor 3, and the front part 4a of the rotating shaft 4 protrudes into the pump chambers 21, 22.

[0029] The bearings 51 and 52 rotatably support the rotating shaft 4. Specifically, bearing 51 is located in front of the motor 3, between the motor 3 and the impellers 61 and 62. Bearing 52 is located in rear of the motor 3. Bearings 51 and 52 are, for example, sliding bearings. Bearing 51 is an example of the first bearing in the present invention.

[0030] The impeller 61 draws in and discharges the fluid being handled. The impeller 61 is mounted on the front 4a of the rotating shaft 4 and is housed in the pump chamber 21. The impeller 61 is a known closed-type impeller. The impeller 61 comprises a plurality of blades 61a, a front shroud 61b, a rear shroud 61c, a suction port 61d, a female threaded surface 61e, and a discharge port 61f.

[0031] The blades 61a rotate circumferentially around the rotation axis 4, guiding the liquid being handled, drawn in from the suction port 61d, to the discharge port 61f. The blades 61a are positioned between the front shroud 61b and the rear shroud 61c.

[0032] The front shroud 61b is a plate (so-called side plate) that covers the front of the wing 61a. The shape of the front shroud 61b is roughly ring-shaped, with the inner edge being more convex towards the front than the outer edge.

[0033] The rear shroud 61c is a plate (the so-called main plate) that covers the rearward direction of the blade 61a. The rear shroud 61c has a ring-like shape. In an axial view, the central part of the rear shroud 61c protrudes forward in a roughly frustoconical shape.

[0034] The inner edge of the front shroud 61b extends cylindrically forward so as to be coaxial with the rotation axis 4, forming the suction port 61d. In other words, the front shroud 61b is provided with the suction port 61d. The front half of the inner circumferential surface of the suction port 61d is an internal threaded surface 61e.

[0035] The discharge port 61f is the outlet for the liquid being handled that flows through the impeller 61. The discharge port 61f is located on the outer edge of the impeller 61.

[0036] The portion of the impeller 61 excluding the suction port 61d is housed in the pump chamber 21. The suction port 61d is housed in the large-diameter section 23a. Between the front inner surface 21a and the large-diameter section 23a and the impeller 61 (front shroud 61b and suction port 61d), a space S1 is formed into which a portion of the liquid being handled discharged from the impeller 61 flows. In other words, the front inner surface 21a and the large-diameter section 23a and the impeller 61 (front shroud 61b and suction port 61d) define space S1.

[0037] The impeller 62 draws in and discharges the handling fluid. The impeller 62 is attached to the front part 4a of the rotating shaft 4 and is housed in the pump chamber 22. The configuration of the impeller 62 is the same as that of the impeller 61, except that the impeller 62 does not have a surface corresponding to the female screw surface 61e. Therefore, a detailed explanation thereof is omitted.

[0038] Figure 3 is a partially enlarged schematic cross-sectional view of part B of the pump device 1 in Figure 2. In the following explanation, Figure 2 will be referred to as appropriate, along with Figure 3.

[0039] The inducer 7 rotates in accordance with the rotation of the rotating shaft 4, thereby pressurizing the fluid being handled and assisting the impeller 61 in drawing the fluid in. The inducer 7 is a so-called hubless inducer, lacking a hub portion attached to the rotating shaft 4. The inducer 7 is housed in the large-diameter section 23a and the medium-diameter section 23b. The inducer 7 is positioned in front of (upstream of) the impeller 61 and is attached to the suction port 61d of the impeller 61. The inducer 7 comprises a shroud 71 and a plurality (three in this embodiment) of inducer blades 72.

[0040] The shroud 71 houses the inducer blade 72. The shape of the shroud 71 is cylindrical. The shroud 71 has an outer circumferential surface 71a, an inner circumferential surface 71b, a front end surface 71c, a helical groove 71d, a male threaded surface 71e, a plurality (four in this embodiment) end face grooves 71f, and a plurality (three in this embodiment) through holes 71g.

[0041] The outer circumferential surface 71a and the inner circumferential surface 71b are cylindrical in shape. The front end surface 71c is an opening surface facing forward. The front end surface 71c is planar in the vertical direction and ring-shaped when viewed from the front. The outer circumferential surface 71a is an example of the outer circumferential surface of the shroud in this invention. The inner circumferential surface 71b is an example of the inner circumferential surface of the shroud in this invention. The front end surface 71c is an example of the end surface of the shroud in this invention.

[0042] A cylindrical space (hereinafter referred to as "first cylindrical space S2") is formed between the large-diameter portion 23a and the outer circumferential surface 71a, in which the inducer bearing 8 is located. In other words, the housing 2 and the shroud 71 define the first cylindrical space S2. The first cylindrical space S2 is in communication with space S1. A cylindrical space (hereinafter referred to as "second cylindrical space S3") is formed between the medium-diameter portion 23b and the outer circumferential surface 71a, through which the handling fluid flowing in from the impeller 61 flows. In other words, the housing 2 and the shroud 71 define the second cylindrical space S3. The second cylindrical space S3 is located in front of the inducer bearing 8. The second cylindrical space S3 is in communication with the internal space of the bypass flow path 23f and the first cylindrical space S2. The second cylindrical space S3 is an example of the first space in the present invention. The second stage portion 23e is positioned in the forward direction of the front end surface 71c, spaced apart from the front end surface 71c, and facing the front end surface 71c. A ring-shaped gap (hereinafter referred to as "end face gap S4") is formed between the second stage portion 23e and the front end surface 71c. In other words, the second stage portion 23e and the front end surface 71c define the end face gap S4. The end face gap S4 communicates with the internal space of the bypass flow path 23f and the second cylindrical space S3. The flow path outlet 23h of the bypass flow path 23f opens at a position located in the forward direction (upstream side in the flow of the liquid being handled in the suction hole 23) of the inducer 7. That is, the internal space of the bypass flow path 23f communicates with the space (hereinafter referred to as "upstream space S5") located in the internal space of the suction hole 23 that is located in the forward direction (upstream side) of the inducer 7.

[0043] Figure 4 is a schematic perspective view of inducer 7. For the sake of clarity, the diagram omits some of the components of the inducer 7. In the following explanation, Figures 2 and 3 will be referred to as appropriate, along with Figure 4.

[0044] The spiral groove 71d is a spiral groove that, in response to the rotation of the rotating shaft 4 (inducer 7), directs the liquid being handled from the rear to the front (second cylindrical space S3) as it flows into the first cylindrical space S2. The spiral groove 71d is positioned on the outer circumferential surface 71a from the front end to the center. The spiral groove 71d is positioned on the outer circumferential surface 71a such that its position rotates along the rotational direction RD of the rotating shaft 4 as it moves from the front (downstream side in the flow of the liquid being handled in space S1) to the rear (upstream side in the same flow).

[0045] The male threaded surface 71e corresponds to the female threaded surface 61e of the impeller 61. The male threaded surface 71e is located at the rear end of the outer peripheral surface 71a. The male threaded surface 71e is fitted into the female threaded surface 61e. As a result, the inducer 7 (shroud 71) is attached to the impeller 61 (inlet 61d).

[0046] Figure 5 is a schematic front view of the inducer 7. For the sake of clarity, the diagram omits some of the components of the inducer 7. In the following explanation, Figures 2 and 3 will be referred to as appropriate, along with Figure 5.

[0047] The end face groove 71f is a groove (recess) that, in response to the rotation of the rotating shaft 4 (inducer 7), directs the handling fluid that has flowed into the end face gap S4 from the radially inward direction to the radially outward direction. In the circumferential direction, the end face grooves 71f are arranged on the front end face 71c at equal angular (90°) intervals. In a forward view, the end face grooves 71f are arranged on the front end face 71c such that they trace an arc from the front to the rear in the rotational direction RD as the end face grooves 71f move from the inner circumferential surface 71b (radially inward direction) to the outer circumferential surface 71a (radially outward direction). The end face groove 71f is an example of a recess in the present invention.

[0048] The through-holes 71g are through-holes that open into the outer circumferential surface 71a and the inner circumferential surface 71b. In the circumferential direction, the through-holes 71g are arranged at equal angular (120°) intervals at the front of the shroud 71. The through-holes 71g include an opening 71h that opens into the outer circumferential surface 71a and an opening 71i that opens into the inner circumferential surface 71b.

[0049] Figure 6 is a partially enlarged schematic diagram of the inducer 7, showing the position of the opening 71h. Figure 7 is a partially enlarged schematic diagram of the inducer 7, showing the position of the opening 71i. In the following explanation, Figures 2 and 3 will be referred to as appropriate, along with Figures 6 and 7.

[0050] The opening 71h is located opposite the middle diameter portion 23b (facing the second cylindrical space S3). Furthermore, a portion of the opening 71h of some of the through holes 71g opens into the helical groove 71d. The opening 71i is located forward of the negative pressure surface 72b (described later) and is close to the negative pressure surface 72b. That is, the internal space of the through hole 71g is in communication with the second cylindrical space S3, the internal space of the helical groove 71d, and the internal space of the inducer 7.

[0051] The "position close to the negative pressure surface 72b" is a position in which, in a radial view, at least a portion of the opening 71i faces the vicinity of the negative pressure surface 72b and the region where the pressure of the liquid being handled is reduced (hereinafter referred to as the "negative pressure surface region Rn"). In this embodiment, the opening 71i is located at the position indicated by "P1" in Figure 7.

[0052] In this invention, the opening 71i may be positioned at the locations indicated by "P2" and "P3" in Figure 7. Alternatively, the opening 71i may be positioned adjacent to the leading edge LE of the negative pressure surface 72b.

[0053] In the following explanation, Figures 2 and 3 will be the primary references. The inducer blades 72 rotate in accordance with the rotation of the rotation axis 4. The inducer blades 72 protrude from the inner circumferential surface 71b toward the inside of the shroud 71. The inducer blades 72 have a positive pressure surface 72a and a negative pressure surface 72b. The positive pressure surface 72a is the surface oriented in the rotation direction RD of the inducer 7. The negative pressure surface 72b is the surface oriented in the opposite direction to the rotation direction RD. That is, the negative pressure surface 72b is the surface opposite to the positive pressure surface 72a. In the circumferential direction, the inducer blades 72 are arranged at equal angular (120°) intervals.

[0054] The inducer bearing 8 rotatably supports the inducer 7 (outer surface 71a). The inducer bearing 8 is, for example, a known sliding bearing. The inducer bearing 8 is located in the front half of the first cylindrical space S2. That is, radially, the inducer bearing 8 is located outward from the inducer 7. As a result, behind the inducer bearing 8 is the rear part of the first cylindrical space S2, and the space defined by the housing 2, the inducer 7, and the inducer bearing 8 (hereinafter referred to as the "rear space S21"). The inducer bearing 8 comprises a bearing housing 81, a bearing body 82, and a pin 83. The inducer bearing 8 is an example of the second bearing in the present invention. The rear space S21 is an example of the second space in the present invention.

[0055] The bearing housing 81 houses the bearing body 82. The bearing housing 81 has a male threaded surface 81a. The male threaded surface 81a corresponds to the female threaded surface 23j and is located on the outer circumferential surface of the bearing housing 81. The bearing housing 81 is attached to the large diameter portion 23a and the first stage portion 23d by the male threaded surface 81a being fitted into the female threaded surface 23j. The bearing body 82 rotatably supports the inducer 7. The shape of the bearing body 82 is cylindrical. The bearing body 82 has a cylindrical inner circumferential surface 82a. The bearing body 82 is housed in the bearing housing 81 and is located between the bearing housing 81 and the shroud 71 (outer circumferential surface 71a). The pin 83 fixes the position of the bearing body 82 in the circumferential direction.

[0056] An inducer 7 is inserted through the bearing body 82. A small gap S22 is formed between the outer circumferential surface 71a of the shroud 71 and the inner circumferential surface 82a of the bearing body 82. When the rotating shaft 4 (inducer 7) is rotating, a lubricating film (not shown) is formed in the gap S22 by the handling fluid. A helical groove 71d is arranged on the portion of the outer circumferential surface 71a that faces the bearing body 82.

[0057] ● Operation of the pump device Next, the operation of the pump device 1 will be explained below, focusing on the flow of the liquid being handled in the suction port 23. Figures 1 to 3 will be referred to as appropriate in the following explanation.

[0058] Figure 8 is a schematic cross-sectional view showing the flow of the liquid being handled in the suction port 23 when the pump device 1 is operating. This figure shows the same cross-section as the pump device 1 in Figure 3. In this figure, the flow of the liquid being handled F0 to F8 is indicated by arrows.

[0059] When the pump device 1 is operating, the impellers 61, 62 and inducer 7 rotate in accordance with the rotation of the rotating shaft 4. The inducer 7 draws in the handling fluid introduced into the small diameter section 23c and discharges it toward the suction port 61d of the impeller 61. At this time, within the inducer 7, the pressure of the handling fluid in the region near the positive pressure surface 72a (hereinafter referred to as the "positive pressure region") increases, and the pressure of the handling fluid in the negative pressure region Rn decreases. The impeller 61 draws in the handling fluid and discharges it into the pump chamber 21. The handling fluid discharged into the pump chamber 21 is sent to the pump chamber 22 via the connecting passage 27. At this time, a portion of the handling fluid discharged into the pump chamber 21 flows into the rear space S21 via space S1 (flow F1). The fluid being handled flows into the rear space S21 and returns to the suction hole 23 through the inducer bearing 8 (gap S22), the second cylindrical space S3, and the end face gap S4 (flow F5). This returning fluid flow F5 disrupts the main flow F0 just before it is drawn into the inducer 7, negatively affecting the suction performance of the inducer 7 (pump device 1). For this reason, flows F1 and F5 are generally suppressed by orifices or labyrinth structures. However, as described later, the pump device 1 actively utilizes flow F1 to improve the lubrication (formation of a lubricating film) and cooling effects of the inducer bearing 8.

[0060] In pump device 1, the inducer 7 is supported by an inducer bearing 8, which is not present in conventional pumps. Therefore, pump device 1 is equipped with a structure (hereinafter referred to as the "introduction structure") that actively introduces the fluid being handled into the inducer bearing 8 in order to improve the lubrication and cooling effect of the fluid being handled into the inducer bearing 8. In this embodiment, the helical groove 71d and the through hole 71g mainly function as the introduction structure.

[0061] As described above, the helical groove 71d is formed on the outer surface 71a such that it pivots along the rotational direction RD of the rotating shaft 4 as the position of the helical groove 71d moves from the front to the rear. In the radial direction, the gap S22 between the outer surface 71a of the shroud 71 and the inner surface 82a of the bearing body 82 is extremely small (large enough for a lubricating film to form). Therefore, most of the handling fluid (flow F2) that flows into the rear space S21 flows through the helical groove 71d (flow F3). When the rotating shaft 4 rotates, the helical groove 71d functions as a screw that transports the handling fluid from the rear direction (upstream side in the flow of handling fluid in space S1: rear space S21) to the front direction (downstream side in the same flow: second cylindrical space S3) of the inducer bearing 8. As a result, the amount of handling fluid (flow F1) flowing into the rear space S21 increases, and the amount of handling fluid (flow F2) flowing into the gap S22 also increases. Therefore, a sufficient amount of handling fluid is available for the lubrication and cooling of the inducer bearing 8. As a result, the lubrication and cooling effects of the inducer bearing 8 are improved.

[0062] Furthermore, as mentioned above, the second cylindrical space S3 is in communication with the internal space of the through hole 71g. The opening 71i of the through hole 71g is located in the vicinity of the negative pressure surface 72b, in the direction in front of the negative pressure surface 72b. Therefore, a portion of the handling fluid supplied to the second cylindrical space S3 flows into the internal space of the inducer 7 through the through hole 71g (flow F4). Flow F4 may disturb the main flow F0 of the handling fluid in the internal space of the inducer 7. However, immediately after flowing into the internal space of the inducer 7, flow F4 flows into the negative pressure surface region Rn without flowing into the main flow F0 of the handling fluid in the internal space of the inducer 7. At this time, flow F4 disturbs the flow Fn in the negative pressure surface region Rn without disturbing the main flow F0 of the handling fluid. As a result, separation of the handling fluid at the negative pressure surface 72b is suppressed, and the occurrence of cavitation in the internal space of the inducer 7 is suppressed. Furthermore, the fluid being handled in the through-hole 71g is drawn into the negative pressure surface region Rn. As a result, a portion of the fluid being handled that is delivered to the second cylindrical space S3 is drawn into the through-hole 71g. Consequently, the amount of fluid being handled that flows into the gap S22 (flow F2) increases, and the amount of fluid being handled that flows into the rear space S21 (flow F1) also increases. Therefore, the flow rate of the fluid being handled that is used for lubrication and cooling of the inducer bearing 8 increases. A portion of the opening 71h opens into the helical groove 71d. As a result, a portion of the fluid being handled that is delivered through the helical groove 71d (flow F3) flows directly from the helical groove 71d into the through-hole 71g (flow F4). In this way, the through-hole 71g also functions as an introduction structure.

[0063] The remaining handling fluid delivered to the second cylindrical space S3 flows into the end face gap S4 (flow F5) and the bypass channel 23f (flow F6). The end face gap S4 is faced by the end face groove 71f. As described above, the end face groove 71f is formed on the front end face 71c such that it traces an arc from the front to the rear in the rotational direction RD as the end face groove 71f moves from the inner circumferential surface 71b to the outer circumferential surface 71a. Therefore, when the rotating shaft 4 rotates, the end face groove 71f functions like a wing that directs the handling fluid that has flowed into the end face gap S4 from the inward to the outward direction in the radial direction. As a result, a flow F7 is generated in the handling fluid in the end face gap S4, moving from the inward to the outward direction in the radial direction. This flow F7 becomes stronger the narrower the end face gap S4 is in the front-rear direction (axial direction). The flow F7 suppresses the flow F5 from the second cylindrical space S3 to the end face gap S4. Therefore, the majority of the remaining handling fluid delivered to the second cylindrical space S3 flows into the bypass channel 23f (flow F6) and is returned to the main flow F0 of the handling fluid flowing through the small diameter section 23c from the channel outlet 23h (flow F8). As mentioned above, the front end 23i of the bypass channel 23f on the channel outlet 23h side is inclined more in the rear direction than in the radial direction. Therefore, the flow F8 returned to the main flow F0 merges with the main flow F0 along the main flow F0 and does not affect the main flow F0. In addition, the channel outlet 23h is located at a position further forward than the inducer 7. Therefore, even if the main flow F0 is affected by flow F8, that effect is absorbed by other flows before the handling fluid is drawn into the inducer 7.

[0064] In conventional pump systems (hereinafter referred to as "conventional pumps"), which have a structure in which the impeller and inducer are not positioned between the bearings (so-called overhang structure), the impeller and inducer are positioned outside (forward) between the bearings. Therefore, in conventional pumps, the rotating shaft located in front of the bearings deforms and vibrates according to the weight of the impeller and inducer. In other words, the rotor dynamics of conventional pumps can be greatly reduced.

[0065] In contrast, in the pump device 1, the inducer 7, which is positioned forward of the bearing 51, is supported by the inducer bearing 8. That is, the front end (front part 4a) of the rotating shaft 4 is supported by the inducer bearing 8 via the impeller 61 and inducer 7. Also, the impellers 61 and 62 are positioned between the bearing 51 and the inducer bearing 8. Therefore, deformation and vibration of the rotating shaft 4 (front part 4a) located forward of the bearing 51 are suppressed. In other words, the rotor dynamics of the pump device 1 are improved.

[0066] Figure 9 shows the simulation analysis results of the rotor dynamics of pump device 1. Figure 10 is the Campbell diagram of the pump device 1 used in the simulation in Figure 9. Figure 9 also shows the analysis results of a pump device 1 that mimics a conventional pump (a pump device 1 without an inducer bearing 8) as a comparative example. Similarly, Figure 10 also shows the Campbell diagram of a pump device 1 that mimics a conventional pump as a comparative example. The vertical axis in Figure 10 shows the natural frequency of the rotating body (rotating shaft 4), and the horizontal axis shows the rotational speed of the rotating body. In Figure 10, the critical speed for each bending mode is indicated by a circle ("○").

[0067] As shown in Figure 9, when the inducer 7 is not supported by the inducer bearing 8, the rotating shaft 4 deforms significantly, starting near the bearing 51. In particular, the front end (inducer 7) of the rotating body (rotating shaft 4, impellers 61, 62, and inducer 7) becomes a free end and is greatly displaced radially outward. The front end of the rotating shaft 4 is displaced to the maximum extent, with a displacement of "0.0095 mm". On the other hand, when the inducer 7 is supported by the inducer bearing 8, the radial displacement of the front end of the rotating body is restricted by the inducer bearing 8. That is, the free end of the rotating body becomes a fixed end (the pump device 1 does not have an overhang structure). As a result, the rotating shaft 4 deforms, starting near the bearing 51 and the inducer bearing 8. The portion of the rotating shaft 4 between the bearing 51 and the inducer bearing 8 is displaced to the maximum extent, with a displacement of "0.0013 mm". Thus, in the pump device 1, because the inducer 7 is supported by the inducer bearing 8, the pump device 1 does not have an overhang structure. As a result, the amount of displacement is greatly reduced, and the rotor dynamics are improved. Consequently, as shown in Figure 10, the natural frequencies of the primary bending mode and the secondary bending mode increase in the Campbell diagram, and the critical speed increases from approximately 20,000 rpm to approximately 50,000 rpm.

[0068] Thus, in the pump device 1, the inducer bearing 8 supports the inducer 7 (shroud 71), which corresponds to the tip of the overhang structure. As a result, the rotor dynamics are improved compared to conventional pumps equipped with an overhang structure. Furthermore, the inducer bearing 8 does not support the rotating shaft 4 and is positioned radially outward from the inducer 7. That is, in the axial direction, the inducer bearing 8 is not positioned alongside the impellers 61, 62 and the inducer 7. As a result, in the axial direction, space for arranging the inducer bearing 8 is not required in the pump device 1, and the overall length of the pump device 1 remains the same as that of a conventional device. In other words, the overall length of the pump device 1 does not change whether or not the inducer bearing 8 is present. In addition, in the pump device 1, the helical groove 71d and through hole 71g actively allow the handling fluid for lubrication and cooling of the inducer bearing 8 to flow into the rear space S21. Therefore, even though the inducer bearing 8 is positioned between the housing 2 and the inducer 7, there is no lack of lubrication and cooling for the inducer bearing 8. Consequently, the inducer bearing 8 functions normally. Furthermore, in the pump device 1, the fluid being handled, which has been delivered to the second cylindrical space S3, is returned to the fluid being handled in the suction hole 23 without affecting the main flow F0, thanks to the bypass passage 23f, the end face groove 71f, and the through hole 71g. Consequently, the suction performance of the pump device 1 is not reduced.

[0069] ●Summary According to the embodiment described above, the pump device 1 comprises a motor 3, a rotating shaft 4, bearings 51, 52, impellers 61, 62, an inducer 7, and an inducer bearing 8. In the axial direction, the direction in which the inducer 7 is positioned relative to the impellers 61, 62 is the forward direction, and the direction in which the impellers 61, 62 are positioned relative to the inducer 7 is the rear direction. The inducer 7 comprises inducer blades 72 and a shroud 71. The shroud 71 has an outer circumferential surface 71a. The inducer bearing 8 supports the outer circumferential surface 71a. With this configuration, the radial movement of the front end of the rotating body (rotating shaft 4, impellers 61, 62, and inducer 7) is restricted by the inducer bearing 8. As a result, rotor dynamics are improved. Furthermore, space for arranging the inducer bearing 8 is not required in the axial direction, and the overall length of the pump device 1 does not change with or without the inducer bearing 8. Thus, in the pump device 1, the rotor dynamics are improved without increasing the overall length of the pump device 1.

[0070] Furthermore, according to the embodiment described above, the housing 2 and shroud 71 define a second cylindrical space S3 in the forward direction of the inducer bearing 8 and a rear space S21 in the rear direction of the inducer bearing 8. A portion of the handling fluid discharged from the impeller 61 flows into the rear space S21. The inducer 7 is equipped with a helical groove 71d. The helical groove 71d is formed on the outer circumferential surface 71a such that the position of the helical groove 71d pivots along the rotational direction RD of the rotating shaft 4 as it moves from the forward direction to the rear direction. With this configuration, when the rotating shaft 4 rotates, the helical groove 71d functions as a screw that delivers the handling fluid toward the inducer bearing 8 and the second cylindrical space S3. As a result, the flows F1 and F2 increase. Therefore, a sufficient amount of handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured. In other words, the lubrication and cooling effects of the inducer bearing 8 are improved.

[0071] Furthermore, according to the embodiment described above, the inducer 7 is provided with through holes 71g opening in the outer circumferential surface 71a and the inner circumferential surface 71b. The through holes 71g open forward relative to the negative pressure surface 72b. With this configuration, the flow F4 flows into the negative pressure surface region Rn without merging with the main flow F0. As a result, the generation of cavitation in the internal space of the inducer 7 is suppressed. Also, the handling fluid in the through holes 71g is drawn into the negative pressure surface region Rn. As a result, the flows F1 and F2 increase. Therefore, a sufficient amount of handling fluid necessary for lubrication and cooling of the inducer bearing 8 is secured. In other words, the lubrication and cooling effects of the inducer bearing 8 are improved.

[0072] Furthermore, according to the embodiments described above, the shroud 71 is provided with a front end surface 71c. The housing 2 is provided with a second stage portion 23e. The second stage portion 23e is positioned in the forward direction of the front end surface 71c, spaced apart from the front end surface 71c, and facing the front end surface 71c. In a forward view, the end face groove 71f is positioned on the front end surface 71c such that as the end face groove 71f moves from the inner circumferential end to the outer circumferential end, it traces an arc that moves from the forward direction to the rear direction in the rotational direction RD. With this configuration, the flow F5 is suppressed, and the turbulence of the main flow F0 based on the flow F5 is suppressed. As a result, the suction performance of the pump device 1 is improved.

[0073] Furthermore, according to the embodiment described above, the housing 2 is provided with a bypass passage 23f. The internal space of the bypass passage 23f communicates with the end face gap S4 and the upstream space S5 of the suction hole 23, which is located in the forward direction of the inducer 7. The front end portion 23i of the bypass passage 23f is inclined in the rearward direction rather than the radial direction. With this configuration, the decrease in the suction performance of the pump device 1 based on the flow F8 is suppressed.

[0074] Furthermore, according to the embodiment described above, the shroud 71 is attached to the impeller 61. In the radial direction, the inducer blade 72 protrudes inward from the inner circumferential surface 71b. That is, the inducer 7 is a hubless inducer. With this configuration, the suction performance of the pump device 1 is improved.

[0075] Furthermore, according to the embodiments described above, the inducer bearing 8 is a sliding bearing. The helical groove 71d is located on the outer surface 71a, on the portion facing the inducer bearing 8. With this configuration, a sufficient amount of handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured. In other words, the lubrication and cooling effects of the inducer bearing 8 are improved.

[0076] ●Differentiation● Next, a modified version of the pump device 1 will be described below, focusing on the parts that differ from the embodiment described above (hereinafter referred to as the "first embodiment"). In the following description of the modified version, elements that are the same as those in the first embodiment and elements that have common functions are denoted by the same reference numerals as in the first embodiment for the sake of explanation, and their descriptions will be omitted. Figures 1 to 8 will be referred to as appropriate in the following description.

[0077] ●Differences 1 to 5 Figure 11 shows partially enlarged schematic cross-sectional views of the pump device 1 in each modified example, where (a) shows the pump device 1 in the first modified example, (b) shows the pump device 1 in the second modified example, (c) shows the pump device 1 in the third modified example, (d) shows the pump device 1 in the fourth modified example, and (e) shows the pump device 1 in the fifth modified example.

[0078] As shown in Figure 11(a), in the first modified example, the pump device 1 does not have a bypass passage 23f. In this configuration, the handling fluid necessary for lubrication and cooling of the inducer bearing 8 is sufficiently supplied by flows F3 and F4, as in the first embodiment. On the other hand, since there is no flow F6 directed toward the bypass passage 23f, the flow rates of flows F4 and F5 increase compared to the first embodiment. As a result, flow F5 may slightly disturb the main flow F0. Meanwhile, flow F4 is more likely to disturb flow Fn, and cavitation can be further suppressed.

[0079] As shown in Figure 11(b), in the second modified example, the pump device 1 does not have a bypass passage 23f and a helical groove 71d. In this configuration, flows F4 and F5 increase compared to the first embodiment, similar to the first modified example. Also, because the flow F3 due to the helical groove 71d is eliminated, the flow rates of flows F1 and F2 decrease compared to the first modified example. Even in this state, flow F2 is maintained by flow F4, and sufficient handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured.

[0080] As shown in Figure 11(c), in the third modified example, the pump device 1 does not have an end face groove 71f. In this configuration, flow F7 is eliminated except for the flow based on the main flow F0. Therefore, the flow rate of flow F5 increases compared to the first embodiment, and flow F5 may slightly disturb the main flow F0. On the other hand, the handling fluid necessary for lubrication and cooling of the inducer bearing 8 is sufficiently supplied by flows F3 and F4, as in the first embodiment.

[0081] As shown in Figure 11(d), in the fourth modified example, the pump device 1 does not have a through hole 71g. In this configuration, the flow F4 through the through hole 71g is eliminated, so the flow rates of flows F1 and F2 are reduced compared to the first modified example. Also, the cavitation suppression effect as in the first embodiment cannot be obtained. On the other hand, flow F2 is ensured by flow F3, and sufficient handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured.

[0082] As shown in Figure 11(e), in the fifth modified example, the pump device 1 is equipped with a rolling bearing instead of a sliding bearing as the inducer bearing 8. Furthermore, the helical groove 71d is not located in the region facing the inducer bearing 8, but is located only in the forward direction of the inducer bearing 8 (facing the second cylindrical space S3). If the inducer bearing 8 is a rolling bearing, and the helical groove 71d is formed in the region facing the inducer bearing 8, the fluid being handled that flows into the rear space S21 will flow mostly into the helical groove 71d rather than the rolling elements. In this case, the lubrication and cooling effects of the inducer bearing 8 may be reduced. In the fifth modified example, the helical groove 71d is located only on the forward side of the inducer bearing 8 so that the fluid being handled that flows into the rear space S21 flows towards the rolling elements (flow F9).

[0083] In the fifth modified example, the helical groove 71d may also be positioned in the rearward direction of the inducer bearing 8.

[0084] ●Other Embodiments● In addition, in this invention, the housing 2 may be disassembled into multiple parts.

[0085] Furthermore, in this invention, the number of impellers 61 and 62 is not limited to "2". That is, for example, the number of impellers 61 and 62 may be "1" or "3" or more. Here, the greater the number of impellers 61 and 62, the greater the effect of improving rotor dynamics.

[0086] Furthermore, in the present invention, the pump device 1 does not need to be equipped with a bypass flow path 23f, as shown in the first and second modified examples.

[0087] Furthermore, in the present invention, the pump device 1 does not need to be provided with an end face groove 71f, as shown in the third modified example.

[0088] Furthermore, in the present invention, the pump device 1 does not need to have a through hole 71g, as shown in the fourth modified example.

[0089] Furthermore, in the present invention, the pump device 1 does not necessarily have to be equipped with a helical groove 71d, an end face groove 71f, and a through hole 71g. In this configuration, the flow rates of flows F1 and F2 are reduced compared to the first embodiment. However, as mentioned above, the pressure of the fluid being handled that flows into the rear space S21 is high. Therefore, the fluid being handled easily flows into the gap S22. Thus, the fluid being handled necessary for lubrication and cooling of the inducer bearing 8 is secured. Subsequently, the fluid being handled flows into the second cylindrical space S3. A portion of the fluid being handled flows not only into the end face gap S4 but also into the bypass flow path 23f. Therefore, turbulence in the main flow F0 is suppressed.

[0090] Furthermore, in the present invention, the pump device 1 does not necessarily have to be equipped with a bypass passage 23f, an end face groove 71f, and a through hole 71g. In this configuration, the flows F1 and F2 are reduced compared to the first embodiment. Also, all of the handling fluid delivered to the second cylindrical space S3 flows into the end face gap S4. Therefore, the suction performance of the pump device 1 may decrease. On the other hand, sufficient handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured.

[0091] Furthermore, in the present invention, the pump device 1 does not necessarily have to be equipped with a bypass passage 23f, a helical groove 71d, and an end face groove 71f. In this configuration, the flow rates of flows F1 and F2 are reduced compared to the first embodiment. Also, a portion of the handling fluid delivered to the second cylindrical space S3 flows into the end face gap S4. On the other hand, as described above, sufficient handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured. In addition, the occurrence of cavitation in the internal space of the inducer 7 is suppressed.

[0092] Furthermore, in the present invention, the pump device 1 does not necessarily have to be equipped with a helical groove 71d and a through hole 71g. In this configuration, the flow rates of flows F1 and F2 are reduced compared to the first embodiment. However, as described above, the handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured. Also, most of the handling fluid that flows into the second cylindrical space S3 flows into the bypass flow path 23f. Therefore, turbulence in the main flow F0 is suppressed.

[0093] Furthermore, in the present invention, the pump device 1 does not necessarily have to be equipped with a bypass passage 23f, a helical groove 71d, an end face groove 71f, and a through hole 71g. In this configuration, the effects based on these configurations cannot be obtained. On the other hand, the handling fluid necessary for lubrication and cooling of the inducer bearing 8 is ensured.

[0094] Furthermore, in the present invention, the shroud 71 may have a protrusion instead of an end face groove 71f. In this case, when viewed from the front, the protrusion is positioned on the front end face 71c such that the end face groove 71f traces an arc from the front to the rear in the rotational direction RD as it moves from the inner end to the outer end. Here, the shape of the protrusion when viewed from the front may be the same as the shape of the end face groove 71f.

[0095] Furthermore, in the present invention, the number of end face grooves 71f is not limited to "4".

[0096] Furthermore, in the present invention, the number of through holes 71g is not limited to "3". Preferably, the through holes 71g are arranged in correspondence with the inducer blades 72. Also, the number of through holes 71g for one inducer blade 72 is not limited to "1" and can be determined according to the design of the pump device 1.

[0097] Furthermore, in the present invention, some of the multiple through holes 71g do not need to open into the helical groove 71d.

[0098] Furthermore, in the present invention, not all through holes 71g have to open into the helical grooves 71d.

[0099] Furthermore, in the present invention, the opening 71i of the through hole 71g may open forward of the negative pressure surface region Rn. In this configuration as well, the liquid being handled flows into the negative pressure surface region Rn immediately after entering through the through hole 71g.

[0100] Furthermore, in the present invention, the inducer 7 may be attached to the rotating shaft 4. That is, the inducer 7 may be an inducer that includes a hub portion.

[0101] Furthermore, in the present invention, the number of inducer blades 72 can be determined according to the design of the pump device 1, and is not limited to "3".

[0102] Furthermore, in the present invention, the size of the second cylindrical space S3 in the radial direction may be about the same as the size of the gap S22 (the second cylindrical space S3 may be narrow). In this case, even in the second cylindrical space S3, the liquid being handled is delivered forward by the helical groove 71d. The same applies to the rear space S21.

[0103] Furthermore, in the present invention, the inducer 7 may be fixed to the impeller 61 by bolts.

[0104] Furthermore, in the present invention, the inducer bearing 8 does not necessarily have to include a bearing housing 81 and a pin 83. In this case, the bearing body 82 is fixed to the housing 2, for example, by bolts.

[0105] Furthermore, in the present invention, the method of mounting the bearing housing 81 is not limited to a method using the female threaded surface 23j and the male threaded surface 81a. That is, for example, the bearing housing 81 may be attached to the large-diameter portion 23a and / or the first-stage portion 23d with bolts (not shown).

[0106] Furthermore, in the present invention, the inducer bearing 8 may support the inner circumferential surface 71b. In this case, for example, the front end of the inner circumferential surface of the shroud 71 is larger in diameter than the other parts. The outer circumferential surface of the rear half of the bearing housing 81 is smaller in diameter than the outer circumferential surface of the front half and is inserted into the front end of the shroud 71 from the front. The bearing body 82 is positioned between the front end of the shroud 71 and the rear half of the bearing housing 81. In this configuration, in the axial direction, a part of the inducer bearing 8 overlaps with a part of the inducer 7. Therefore, even with the induction bearing 8 in place, the increase in the overall length of the pump device 1 is suppressed.

[0107] Furthermore, in the present invention, the pump device 1 is not limited to a centrifugal pump, and only requires that an inducer be positioned upstream of the impeller. That is, for example, the pump device 1 may be an axial flow pump or a mixed flow pump.

[0108] ●Embodiments of the present invention● Next, embodiments of the present invention as understood from the embodiments described above will be described below, with reference to the terms and reference numerals used in each embodiment.

[0109] A first embodiment of the present invention comprises a motor (e.g., motor 3), a rotating shaft (e.g., rotating shaft 4) that rotates by the drive of the motor, an impeller (e.g., impellers 61, 62) attached to the rotating shaft for sucking in and discharging the liquid being handled, a first bearing (e.g., bearing 51) disposed between the motor and the impeller to rotatably support the rotating shaft, an inducer (e.g., inducer 7) disposed upstream of the flow of the liquid being handled from the impeller, a second bearing (e.g., inducer bearing 8) that rotatably supports the inducer, and a pump housing (e.g., housing 2) housing the impeller, the inducer and the second bearing. A pump device (e.g., pump device 1) is provided, wherein in the axial direction of the rotating shaft, the direction in which the inducer is positioned relative to the impeller is a first direction (e.g., forward direction), and the direction in which the impeller is positioned relative to the inducer is a second direction (e.g., backward direction), the inducer comprises inducer blades (e.g., inducer blades 72) that rotate in accordance with the rotation of the rotating shaft, and a cylindrical shroud (e.g., shroud 71) that houses the inducer blades, the shroud comprises a cylindrical outer surface of the shroud (e.g., outer surface 71a), and the second bearing supports the outer surface of the shroud. This configuration improves rotor dynamics without increasing the overall length of the pump system.

[0110] A second embodiment of the present invention is a pump device in which, in the first embodiment, the pump housing and the shroud define a first space (e.g., rear space S21) in the first direction of the second bearing and a second space (e.g., second cylindrical space S3) in the second direction of the second bearing, into which a portion of the fluid being handled discharged from the impeller (e.g., impeller 61) flows; the inducer comprises a helical groove (e.g., helical groove 71d) arranged on the outer circumferential surface of the shroud, the helical groove being arranged on the outer circumferential surface of the shroud such that the position of the helical groove revolves along the rotational direction of the rotating shaft (e.g., rotational direction RD) as the direction from the first direction to the second direction. With this configuration, a sufficient amount of handling fluid is ensured to lubricate and cool the inducer bearing.

[0111] A third embodiment of the present invention is a pump device in which, in the first or second embodiment, the shroud comprises a cylindrical inner circumferential surface of the shroud (e.g., inner circumferential surface 71b), the inducer comprises the outer circumferential surface of the shroud and a through hole (e.g., through hole 71g) opening to the inner circumferential surface of the shroud, and the inducer blade comprises a positive pressure surface (e.g., positive pressure surface 72a) and a negative pressure surface (e.g., negative pressure surface 72b) which is the surface opposite to the positive pressure surface, and in the axial direction, the through hole opens in the first direction relative to the negative pressure surface. This configuration suppresses cavitation within the inducer's internal space. Furthermore, it ensures a sufficient amount of fluid is available for lubrication and cooling of the inducer bearing.

[0112] A fourth embodiment of the present invention is a pump device in which, in the third embodiment, the shroud comprises a ring-shaped shroud end face (e.g., a front end face 71c) facing the first direction, the pump housing comprises an opposing surface (e.g., a second stage portion 23e) positioned in the first direction of the shroud end face, spaced apart from the shroud end face and facing the shroud end face, the shroud end face comprises a recess (e.g., an end face groove 71f) or a protrusion, and in a view in the first direction, the recess or the protrusion is positioned on the shroud end face such that the recess or the protrusion traces an arc from the front to the rear in the rotational direction of the rotation axis as the shroud moves from the inner circumferential surface to the outer circumferential surface of the shroud. This configuration improves the suction performance of the pump system.

[0113] A fifth embodiment of the present invention is a pump device in which, in the fourth embodiment, the pump housing comprises a bypass passage (e.g., bypass passage 23f) communicating with a gap (e.g., end face gap S4) defined by the shroud end face and the opposing face, and an upstream space (e.g., upstream space S5) located in the first direction from the inducer within the internal space of the pump housing, wherein the opening end of the bypass passage on the upstream space side (e.g., front end 23i) is inclined in the second direction side more than the radial direction of the rotation axis. In this configuration, the flow returned from the bypass channel to the main channel does not affect the main channel.

[0114] A sixth embodiment of the present invention, in the first or second embodiment, the shroud comprises a cylindrical inner circumferential surface of the shroud (e.g., inner circumferential surface 71b) and a ring-shaped shroud end surface facing the first direction (e.g., front end surface 71c), wherein the pump housing comprises an opposing surface (e.g., second stage portion 23e) positioned spaced apart from the shroud end surface on the first direction side of the shroud end surface and facing the shroud end surface, a gap defined by the shroud end surface and the opposing surface (e.g., end surface gap S4), and an upstream space (e.g., located on the first direction side of the inducer) within the internal space of the pump housing. The pump device comprises an upstream space S5) and a bypass channel (e.g., bypass channel 23f) communicating with it, wherein the open end of the bypass channel on the upstream space side (e.g., front end 23i) is inclined toward the second direction side than the radial direction of the rotation axis, and the shroud end face is provided with a recess (e.g., end face groove 71f) or a protrusion, wherein, in the first view, the recess or the protrusion is arranged on the shroud end face such that as the recess or the protrusion moves from the inner circumferential surface of the shroud toward the outer circumferential surface of the shroud toward the outer circumferential surface of the shroud, it traces an arc from the front to the rear in the rotation direction of the rotation axis. This configuration improves the suction performance of the pump system. Furthermore, the flow returned from the bypass channel to the main channel does not affect the main channel itself.

[0115] A seventh embodiment of the present invention is a pump device in which, in the first embodiment, the shroud comprises a cylindrical inner surface of the shroud (e.g., inner surface 71b), the shroud is attached to the impeller (e.g., impeller 61), and the inducer blades protrude inward from the inner surface of the shroud in the radial direction of the rotation axis. This configuration improves the suction performance of the pump system.

[0116] An eighth embodiment of the present invention is a pump device in which, in the second embodiment, the second bearing is a sliding bearing, and the helical groove is arranged on the outer surface of the shroud in a portion facing the second bearing. This configuration improves the lubrication and cooling effects of the inducer bearing. [Explanation of Symbols]

[0117] 1. Pumping device 2 enclosures (pump enclosures) 23e Second section 23f Bypass channel 23i Front end (open end) 3 motors 4 rotation axes 51 Bearing (First Bearing) 61 Impeller 7 Inducer 71 Shroud 71a Outer surface (Shroud outer surface) 71b Inner surface (inner surface of the shroud) 71c Front end face (shroud end face) 71d spiral groove 71f End groove 71g through hole 72 Inducer Wings 72a Pressure side 72b Suction side 8. Inducer bearing (second bearing) S21 Rear space (second space) S3 Second cylindrical space (first space) S4 End face gap (gap) S5 Upper Space

Claims

1. Motor and, A rotating shaft that rotates due to the drive of the aforementioned motor, An impeller attached to the aforementioned rotating shaft, which sucks in and discharges the liquid being handled, A first bearing is positioned between the motor and the impeller and rotatably supports the rotating shaft, An inducer positioned upstream of the flow of the liquid being handled from the impeller, A second bearing rotatably supports the inducer, A pump housing that houses the impeller, the inducer, and the second bearing, It has, In the axial direction of the rotation axis, the direction in which the inducer is positioned relative to the impeller is the first direction, and the direction in which the impeller is positioned relative to the inducer is the second direction. The aforementioned inducer is, An inducer blade that rotates in accordance with the rotation of the aforementioned rotation axis, A cylindrical shroud housing the inducer blade, Equipped with, The aforementioned shroud is, Outer surface of cylindrical shroud, Equipped with, The second bearing supports the outer circumferential surface of the shroud. Pumping device.

2. The pump housing and the shroud are, A first space is defined in the first direction of the second bearing, A second space is defined in the second direction of the second bearing, A portion of the handling fluid discharged from the impeller flows into the second space. The aforementioned inducer is, A spiral groove is arranged on the outer surface of the shroud. Equipped with, The helical groove is positioned on the outer circumferential surface of the shroud such that the position of the helical groove rotates along the rotational direction of the rotation axis as the direction of rotation moves from the first direction to the second direction. The pump device according to claim 1.

3. The aforementioned shroud is, The inner surface of the cylindrical shroud, Equipped with, The aforementioned inducer is, Through holes opening in the outer circumferential surface of the shroud and the inner circumferential surface of the shroud, Equipped with, The aforementioned inducer blade is Positive pressure surface and, The negative pressure surface is the surface opposite to the positive pressure surface, Equipped with, In the axial direction, the through hole opens in the first direction relative to the negative pressure surface. The pump device according to claim 1 or 2.

4. The aforementioned shroud is, The ring-shaped shroud end face facing the first direction, Equipped with, The aforementioned pump housing is A surface positioned in the first direction of the shroud end face, spaced apart from the shroud end face, and facing the shroud end face, Equipped with, The shroud end face is, Recessed or protruding part, Equipped with, In the first viewing direction, the recess or the protrusion is positioned on the end face of the shroud such that as the recess or the protrusion moves from the inner surface of the shroud toward the outer surface of the shroud toward the outer surface of the shroud, it traces an arc that moves from the forward direction to the rear direction in the rotational direction of the rotation axis. The pump device according to claim 3.

5. The aforementioned pump housing is A bypass channel communicating with the gap defined by the shroud end face and the opposing face, and the upstream space of the pump housing located in the first direction relative to the inducer, Equipped with, The open end of the bypass channel on the upstream side is inclined toward the second direction more than the radial direction of the rotation axis. The pump device according to claim 4.

6. The aforementioned shroud is, The inner surface of the cylindrical shroud, The ring-shaped shroud end face facing the first direction, Equipped with, The aforementioned pump housing is On the first direction side of the shroud end face, there is an opposing surface that is spaced apart from the shroud end face and faces the shroud end face, A bypass channel communicating with the gap defined by the shroud end face and the opposing face, and the upstream space located on the first direction side of the inducer within the internal space of the pump housing, Equipped with, The open end of the bypass channel on the upstream side is inclined toward the second direction more than the radial direction of the rotation axis, The shroud end face is, Recessed or protruding part, Equipped with, In the first viewing direction, the recess or the protrusion is positioned on the end face of the shroud such that as the recess or the protrusion moves from the inner surface of the shroud toward the outer surface of the shroud toward the outer surface of the shroud, it traces an arc that moves from the forward direction to the rear direction in the rotational direction of the rotation axis. The pump device according to claim 1 or 2.

7. The aforementioned shroud is, The inner surface of the cylindrical shroud, Equipped with, The shroud is attached to the impeller, In the radial direction of the rotation axis, the inducer blade protrudes inward from the inner circumferential surface of the shroud. The pump device according to claim 1.

8. The second bearing is a sliding bearing, The helical groove is located on the outer surface of the shroud, in the portion facing the second bearing. The pump device according to claim 2.

Images