Suction screw type pump

Abstract

To provide a suction screw type pump capable of preventing or suppressing a problem that foreign matters come around a back surface of a suction screw and is accumulated thereon even when the foreign matters come around the back surface of the suction screw by a mechanism other than catching of the foreign matters on a distal end of a screw operation part.SOLUTION: A suction screw type pump 10 includes a suction screw 20 provided on a distal end of a shaft 12 and integrally rotating with the shaft 12, a casing 40 storing the suction screw 20 therein and provided with a suction port 46 at the center on the front side in an axial direction of the shaft 12 and a discharge port 47 on the side, and a shaft sealing part 15 provided on a back surface of the casing 40 and shaft sealing around the shaft 12. A labyrinth structure 80 for obstructing movement of a foreign matter E which comes around a back surface 38 of the suction screw 20 to a radial inner side is provided in a portion in which the back surface 38 of the suction screw 20 and an inner surface of the casing 40 face each other in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a suction screw pump. [Background technology]

[0002] In the case of pumps that transport sewage sludge or the like as a liquid, a suction screw pump having a suction screw (impeller) with a large passing particle size is used to prevent blockage by impurities such as screen residue during the liquid being transported (see, for example, Patent Document 1). In this type of suction screw pump, for example, as in the suction screw pump 100 shown in Fig. 9, a suction screw 120 is housed in a casing 140. A shaft seal portion 115 is provided in the center of the back surface of the casing 140. The suction screw 120 is integrally formed with a truncated cone-shaped cone portion 132 that is coaxially provided at the tip of the shaft 112, and a single blade 134 that extends spirally radially outward from the cone portion 132.

[0003] When the suction screw pump 100 is driven, the shaft 112 and the suction screw 120 rotate integrally due to the torque from a motor (not shown). As a result, the suction screw pump 100 draws the liquid into the casing 140 from the suction port 146 due to the action of the swirling flow generated by the suction screw 120, and the liquid in the casing 140 becomes pressurized and is discharged from the discharge port 147. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-110316 A Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of suction screw pump 100, a plurality of rear vanes 133 are provided on the rear surface 138 of the cone portion 132 of the suction screw 120 so as to face the front surface 149 of the back cover, as shown in FIG. However, depending on the impurities E, there are cases where the impurities E get around to the back surface 138 of the cone portion 132 and accumulate between the back cover front surface 149. This causes a problem in that the accumulated impurities E inhibit the mother liquor from lubricating the shaft seal portion 115, causing damage to the mechanical seal of the shaft seal portion 115. The outline arrow in the figure shows an image of the impurities E getting around the back surface of the cone portion of the suction screw.

[0006] To address these problems, the technology described in Patent Document 1 above forms an annular step on the inner surface of front cover 143, and when viewed from outside suction port 146, this annular step covers and conceals the tip of screw action portion 135 of blade 134. As a result, the technology described in the document prevents or suppresses the impurities E sucked in through the suction port 146 from getting caught on the tip of the suction screw blade, solving the problem of the impurities wrapping around and accumulating on the back side of the cone section.

[0007] However, while the technology described in Patent Document 1 can prevent or suppress the impurities E from getting caught on the blades 134 at a position upstream of the cone portion 132, it cannot deal with the case where the impurities E sucked in from the suction port 146 get around to the back of the cone portion by a mechanism other than the impurities E getting caught on the tip of the screw action portion 135. Therefore, in this type of suction screw pump, there is still room for improvement in solving the problem of foreign matter getting around and accumulating on the back surface of the cone portion of the suction screw.

[0008] Therefore, the present invention has been made with attention to such problems, and has an object to provide a suction screw pump that can prevent or suppress the problem of impurities being sucked in from the suction port and accumulating on the back side of the cone portion, even if the impurities get around to the back side of the cone portion of the suction screw by a mechanism other than the impurities getting caught on the tip of the screw action portion. [Means for solving the problem]

[0009] In order to solve the above problems, a suction screw pump according to one embodiment of the present invention is a suction screw pump that transports liquid from the front to the rear in the axial direction of a shaft, and is equipped with a suction screw provided at the tip of the shaft and rotating integrally with the shaft, a casing that houses the suction screw and has an suction port at the center of the axial front of the shaft and an outlet port on the side, and a seal section provided on the back of the casing and seals the periphery of the shaft with a mechanical seal, and is characterized in that a labyrinth structure is provided at the portion where the back of the suction screw and the inner surface of the casing face each other in the axial direction, to prevent impurities that have wrapped around the back of the suction screw from moving radially inward.

[0010] According to the present invention, a labyrinth structure is provided at the portion where the back surface of the suction screw and the inner surface of the casing face each other in the axial direction, which prevents impurities that have got around the back surface of the suction screw from moving radially inward. Therefore, even if impurities sucked in from the suction port end up on the back surface of the suction screw by a mechanism other than the impurities getting caught on the tip of the screw action part, the impurities can be prevented from moving radially inward, thereby preventing or suppressing the problem of impurities getting stuck on the back surface of the suction screw and accumulating. Effect of the Invention

[0011] As described above, according to the present invention, the problem of foreign matter getting around and accumulating on the back surface of the suction screw can be prevented or suppressed. [Brief description of the drawings]

[0012] [Figure 1] 1 is an explanatory diagram of one embodiment of a suction screw pump according to one aspect of the present invention, showing a cross section including an axis line. [Diagram 2] FIG. 2 is an enlarged view of a main part of FIG. [Diagram 3] FIG. 2 is a schematic perspective view illustrating a main part in FIG. [Figure 4] FIG. 5 is an explanatory diagram of a modified convex shape (modified example 1) on the rear surface of the suction screw, in which (a) is a schematic oblique view, (b) is a plan view, (c) is a front view, and (d) is a side view (the same applies to Figures 5-8 (modified example 2-5) below). [Diagram 5] FIG. 11 is an explanatory diagram of a modified example (modified example 2) of the shape of the convex portion on the back surface of the suction screw. [Figure 6] FIG. 13 is an explanatory diagram of a modified example (modification example 3) of the shape of the convex portion on the back surface of the suction screw. [Figure 7] FIG. 13 is an explanatory diagram of a modified example (Modification 4) of the shape of the convex portion on the back surface of the suction screw. [Figure 8] FIG. 13 is an explanatory diagram of a modified example (modified example 5) of the shape of the convex portion on the back surface of the suction screw. [Figure 9] FIG. 2 is an explanatory diagram of a comparative example of a suction screw pump according to an embodiment of the present invention, and shows a cross section including an axis. [Figure 10] 10A and 10B are schematic diagrams for explaining the main part in FIG. 9, in which FIG. 10A shows the part seen from the arrow A in FIG. 9, and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc. are different from the actual ones, and the drawings also include parts where the relationship and ratio of dimensions differ from each other. Furthermore, the embodiments described below are merely examples of devices and methods for embodying the technical ideas of the present invention, and the technical ideas of the present invention do not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0014] As shown in Fig. 1, a suction screw pump 10 according to this embodiment includes a frame 14 that supports a shaft (rotating shaft) 12 in a horizontal position. A casing 40 is provided at the front of the frame 14. A shaft seal portion 15 is provided at the center of a back surface 48 of the casing 40, and a bearing portion 16 is provided at the rear of the frame 14. The bearing portion 16 rotatably supports an axial middle portion of the shaft 12 via bearings 18 and 19 at the front and rear of the axial direction.

[0015] In this embodiment, the front end face (left side in FIG. 1) of the journal portion 16 is closed by a bearing cover 52 fixed by a bolt 27. Moreover, the rear end face (right side in FIG. 1) of the journal portion 16 is closed by a bearing cover 54 fixed by a bolt 28. The shaft 12 passes through the front and rear bearing covers 52, 54, respectively, and its tip and base ends protrude from the bearing covers 52, 54, respectively.

[0016] The casing 40 has a casing body 44 in the axial center, a front cover 43 provided in front of the casing body 44, and a back cover 45 provided at the rear of the casing body 44, which are fixed to each other with bolts and nuts. An accommodation space for the suction screw 20 is defined inside the casing 40. The tip of the shaft 12 protrudes into the casing 40. The suction screw 20 having blades 34 is coaxially fixed to the tip of the shaft 12, and the suction screw 20 is cantilevered inside the casing 40. An output shaft of a motor (not shown) is connected to the base end of the shaft 12 so as to be able to transmit driving force.

[0017] The upper part of the casing body 44 is formed with a discharge port 47 that opens upward, and the front cover 43 is formed with a suction port 46 that protrudes forward along the axial direction in the center, with the conical portion of the inner surface of the front cover 43 covering the periphery of the blades 34 of the suction screw 20. A cylindrical holder portion 50 is integrally formed in the center of a back surface 48 of the back cover 45, protruding toward the rear frame 14. A shaft seal portion 15 incorporating, for example, a mechanical seal is coaxially attached to the rear end surface of the holder portion 50. The shaft seal portion 15 seals the rear portion of the tip side of the shaft 12 at the center of the back surface of the back cover 45.

[0018] Here, the suction screw 20 of this embodiment includes a screw body 21 and a hub 30 provided at the rear part of the screw body 21. The screw body 21 is configured by integrally forming a truncated cone-shaped cone portion 32 provided coaxially at the tip of the shaft 12 and a single blade 34 extending spirally radially outward from the cone portion 32. In this embodiment, a male screw 39 is formed at the tip of the shaft 12, and the male screw 39 is screwed into a screw hole 41 opening in the center of the end face of the cone portion 32 on the base end side of the suction screw 20. The tip of the blade 23 has an asymmetric shape that protrudes axially forward beyond the tip of the outer circumferential surface of the cone portion 32. The blade 34 of this embodiment is spirally disposed around the cone portion 32 and integrally includes a screw action portion 35 that protrudes beyond the tip 32s of the cone portion 32 toward the discharge port 47.

[0019] The screw body 21 has a cavity 22 that opens rearward inside the cone portion 32 (the inner surface of the cone portion 32 is a substantially conical cavity 22). A bolt insertion hole 24 for mounting to the shaft 12 is coaxially formed through the tip of the cone portion 32. 2, the screw body 21 is formed at the base end of the cone portion 32 with a hub mounting portion 25, which is a spigot recess into which the outer circumferential surface of the hub 30 is fitted. A hub mounting pin hole 26 is formed on the surface of the hub mounting portion 25 facing axially rearward, and the hub 30 is coaxially engaged with the hub 30 from its axial front side so as to cover the opening of the cavity 22 of the cone portion 32.

[0020] The hub 30 has a disk portion 37 and a boss portion 36 consisting of a plurality of cylindrical steps that protrude forward and backward from the center of the disk portion 37. A threaded portion 31 for mounting is formed along the axis at the center of the boss portion 36. The disk portion 37 has recessed steps formed in appropriate positions so that it can be spigot-fitted into the hub mounting portion 25 on the screw body 21 side.

[0021] Here, in this embodiment, as shown in Figures 2 and 3, a labyrinth structure 80 is provided at the portion where the back surface 38 of the suction screw 20 and the inner surface of the casing 40 (in this embodiment, the front surface 49 of the back cover 45 that constitutes the casing 40) face each other in the axial direction, to hinder the movement of impurities E that have wrapped around the back surface 38 of the suction screw 20 radially inward. The labyrinth structure 80 of this embodiment has a fitting structure between a convex portion 82 on the back surface of the suction screw 20 and an opposing annular concave portion 70 on the front surface 49 of the back cover 45. In particular, the convex portion 82 on the back surface of the suction screw 20 is provided on the outer diameter end portion of each rear vane 81.

[0022] Next, the operation and effects of the suction screw pump 10 of this embodiment will be described. In the suction screw pump 10 of this embodiment, when the shaft 12 and the suction screw 20 rotate together due to the rotational force from an electric motor (not shown), the suction screw 20 generates a swirling flow, which causes the liquid to be sucked into the casing 40 from the suction port 46 at the axial front of the shaft 12 toward the rear, and the liquid in the casing 40 becomes pressurized and is discharged from the discharge port 47.

[0023] Here, in the case of a pump that transports sewage sludge or the like as a liquid, a suction screw (impeller) with a large passing particle size is used to prevent blockage by impurities during the liquid being transported. According to the suction screw 20 of the suction screw pump 10 of this embodiment, the screw action portion 35 is equipped with one blade 34 that protrudes toward the suction port 46 beyond the cone portion 32, making it suitable as a pump that ensures non-blockage.

[0024] However, in the case of a sludge pump with a suction screw that transports sewage sludge, etc., there are cases where highly elastic and stretchable impurities E, such as rubber bands, get mixed in with the sewage sludge flowing into the pump. This type of impurity E wraps around and accumulates on the back side of the suction screw 20, and the accumulated impurities E may inhibit the mother liquor from lubricating the shaft seal 15, causing damage to the mechanical seal.

[0025] In contrast, according to the suction screw pump 10 of this embodiment, as described above, a labyrinth structure 80 is provided at the portion where the back surface 38 of the suction screw 20 and the inner surface of the casing 40 face each other in the axial direction, which prevents impurities E that have wrapped around the back surface 38 of the suction screw 20 from moving radially inward. Therefore, even if the impurities E sucked in from the suction port 46 end up on the back surface 38 of the suction screw 20 by a mechanism other than the impurities E getting caught on the tip of the screw action portion 35, the labyrinth structure 80 can prevent the impurities E from moving radially inward, thereby preventing or suppressing the problem of the impurities E wrapping around and accumulating on the back surface 38 of the suction screw 20 [Invention 1].

[0026] Furthermore, in the suction screw pump 10 of this embodiment, the labyrinth structure 80 has an engagement structure between the convex portion 82 provided on the back surface of the suction screw 20 and the annular concave portion 70 on the front surface 49 of the back cover 45 facing it, so that a labyrinth structure that prevents the radially inward movement of impurities E that have wrapped around the back surface 38 of the suction screw 20 can be realized with a simple structure [Invention 2].

[0027] As described above, the suction screw pump 10 of this embodiment can prevent or suppress the problem of foreign matter getting around and accumulating on the back surface of the suction screw. The suction screw pump according to the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0028] For example, in the above embodiment, the labyrinth structure 80 is configured by an interfitting structure between the convex portion 82 on the back surface of the suction screw 20 and the annular concave portion 70 on the front surface 49 of the back cover 45 facing it, and the convex portion 82 on the back surface of the suction screw 20 is provided on the outer diameter end portion of each rear vane 81, but this is not limited to this example.

[0029] For example, in the above embodiment, the "inner surface of the casing 40" corresponds to the front surface 49 of the back cover 45 that constitutes the casing 40, but depending on the configuration of the casing 40, it is not limited to the presence or absence of the back cover 45, and the surface that faces the back surface 38 of the suction screw 20 on the liquid-contacting surface of the inner wall of the casing 40 can correspond to it.

[0030] Also, for example, the convex portion 82 on the back surface of the suction screw 20 can be provided on the outer diameter end portion of at least one back blade 81. However, as in the suction screw pump 10 of the above embodiment, by providing the convex portion 82 on the back surface of the suction screw 20 on each outer diameter end portion of each back blade 81, each convex portion 82 can hinder the impurities E from moving radially inward, which is more suitable for preventing or suppressing the problem of the impurities E wrapping around and accumulating on the back surface 38 of the suction screw 20 [Invention 3].

[0031] Also, for example, the shape of the convex portion 82 on the back surface of the suction screw 20 can be modified in various ways, as shown in Fig. 4 to Fig. 8. That is, as in Modification 1 shown in Fig. 4, a convex portion 82 protruding in a rectangular parallelepiped shape can be formed on the outer diameter end of each rear vane 81 along the extension shape of each rear vane 81. Such a configuration is suitable for realizing a fitting structure with the annular recess 70 on the front surface 49 of the back cover 45 with a simple configuration.

[0032] 5, for example, a protruding portion 82a protruding along the extending direction of the annular recess 70 of the front surface 49 of the back cover 45 can be added to the outer diameter end of each rear vane 81 in addition to the shape of the protruding convex portion 82 protruding into the rectangular parallelepiped shape. In this case, it is preferable to make the base end side of the protruding portion 82a a reduced-weight portion (82b shown by the dashed line). This configuration is suitable for arranging the engagement with the annular recess 70 of the front surface 49 of the back cover 45 longer along the extending direction of the annular recess 70.

[0033] 6, for example, a protruding portion 82c that protrudes in a pointed shape along the extension direction of the annular recess 70 can be added to the shape of the convex portion 82. This configuration is preferable in that the engagement between the front surface 49 of the back cover 45 and the annular recess 70 is arranged longer along the extension direction of the annular recess 70, and the pointed slope of the protruding portion 82c provides a discharge function that actively discharges the impurities E toward the outside of the annular recess 70.

[0034] 7, it is preferable to form a protrusion 82 that protrudes in a rectangular parallelepiped shape along the extension shape of each rear vane 81 at the outer diameter end of each rear vane 81, and to form a rough surface 82d that exerts a grinding function on the surface of the protrusion 82 that faces the bottom surface side of the annular recess 70. With this configuration, the grinding function can be exerted on the impurities E that have entered between the rough surface 82d of the protrusion 82 and the bottom surface of the annular recess 70. As a result, the impurities E that have entered between the rough surface 82d and the bottom surface of the annular recess can be discharged while being ground.

[0035] Also, as in the fifth modified example shown in FIG. 8, it is preferable to form a rectangular parallelepiped-shaped protrusion 82 on the outer diameter end of each rear vane 81 along the extension shape of each rear vane 81, and to form a blade 82e having a cutting function on the surface of the protrusion 82 that faces the bottom surface of the annular recess 70. In the example shown in the figure, three blades 82e extending along the swirling direction are provided. With this configuration, the cutting function can be exerted on the impurities E that have entered between the blade 82e formed on the protrusion 82 and the bottom surface of the annular recess 70. This allows the impurities E that have entered between the blade 82e and the bottom surface of the annular recess to be cut and discharged. [Explanation of symbols]

[0036] 10. Suction screw pump 12 Shaft (rotating shaft) 14 Frame 15 Shaft seal 16 axis branches 18, 19 Bearings 20 Suction screw 21 Screw body 22 Cavity 23 Feather 24 Bolt insertion hole 25 Hub mounting part 26 Hub mounting pin hole 27, 28 volts 30 Hub 31 Threaded part 32 Cone section 32s tip 34 Feather 35 Screw action part 36 Boss section 37 Disc Section 38 (disc part) back 39 Male thread 40 Casing 41 Screw hole 43 Front cover 44 Casing body 45 Back Cover 46 Intake port 47 Discharge port 48 Back 49 Front 50 Holder part 52, 54 Bearing cover 60 Fixing pin 70 Circular recess (labyrinth groove) 80 Labyrinth Structure 81 Back feather 82 Convex 83 Fixing bolt 100 Suction screw pump 112 Shaft 115 Shaft seal 120 Suction screw 132 Cone section 133 Back feather 134 Feather 135 Screw action part 138 Back 140 Casing 143 Front cover 145 Back Cover 146 Intake port 147 Discharge port 149 Back cover front E. Contaminants

Claims

1. A suction screw pump that transfers liquid from the front to the rear in the axial direction of a shaft, a suction screw provided at the tip of the shaft and rotating integrally with the shaft; a casing that houses the suction screw and has a suction port provided at the center of the axial front of the shaft and a discharge port provided at a side of the shaft; and a shaft seal portion provided on the back of the casing and that seals the periphery of the shaft with a mechanical seal, A suction screw pump characterized in that a labyrinth structure is provided at the portion where the back surface of the suction screw and the inner surface of the casing face each other in the axial direction, which prevents impurities that have wrapped around the back surface of the suction screw from moving radially inward.

2. 2. The suction screw pump according to claim 1, wherein the labyrinth structure has a fitting structure between a convex portion on the back surface of the suction screw and an annular concave portion on the front surface of a back cover opposite thereto.

3. 3. The suction screw pump according to claim 2, wherein the convex portion on the back surface of the screw is provided on an outer diameter portion of a rear vane.

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