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 crushing part 80 for crushing a foreign matter E which comes around a back surface of the suction screw 20 is provided in a portion in which the back surface 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. 5, 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 shaft sealing section provided on the back of the casing and sealing the periphery of the shaft with a mechanical seal, and is characterized in that a crushing section capable of crushing impurities that have gotten around to the back of the suction screw 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.

[0010] According to the present invention, a crushing section capable of crushing impurities that have got around to the back surface of the suction screw is provided at a portion where the back surface of the suction screw and the inner surface of the casing face each other in the axial direction. 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 crushed on the back surface of the suction screw, 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] 2A and 2B are schematic diagrams for explaining the main part in FIG. 1, in which FIG. 2A shows the part seen from the arrow A in FIG. 1, and FIG. 2B shows the part seen from the arrow B in FIG. [Figure 4] FIG. 3 is an explanatory diagram of a modified example of the suction screw pump according to one embodiment of the present invention, showing an enlarged schematic view of a part of the shear blade portion shown in the upper part of FIG. [Diagram 5] 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 6] 6A and 6B are schematic diagrams for explaining the main part in FIG. 5, in which FIG. 6A shows the part seen from the arrow A in FIG. 5, and FIG. 6B shows the part seen from the arrow B in 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 the rear surface of the casing 40, and a shaft support portion 16 is provided at the rear of the frame 14. The shaft support portion 16 rotatably supports an axial middle portion of the shaft 12 via bearings 18 and 19 at the front and rear of the shaft in 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] 2, 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 formed coaxially through the tip of the cone portion 32. In the screw body 21, a hub mounting portion 25, which is a spigot recess into which the outer peripheral surface of the hub 30 is fitted, is formed at the base end of the cone portion 32. A hub mounting pin hole 26 is formed in the surface of the hub mounting portion 25 facing axially rearward, and the hub 30 is coaxially engaged 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] 2 and 3, in this embodiment, a crushing section 80 capable of crushing impurities E that have got around the back surface 38 of the suction screw 20 is provided at a portion where the back surface 38 of the suction screw 20 and the inner surface of the casing 40 (the front surface 49 of the back cover 45 constituting the casing 40 in this embodiment) face each other in the axial direction. The crushing section 80 in this embodiment includes a shear blade 81 and a shear groove 70 facing the shear blade 81, and is configured to be able to crush the impurities E by shearing.

[0022] Specifically, shear blades 80 are detachably attached to the back surface 38 of the disk portion 37 at two circumferentially opposite positions (positions spaced 180° apart) by fixing bolts 83 (see FIG. 3(a)). Each shear blade 80 is made of carbon tool steel (e.g., SK105) and formed into a generally L-shape in cross section, with the protruding side of the generally L-shape forming a blade portion 82, which is sharpened by grinding after heat treatment.

[0023] In contrast, the shear grooves 70 are provided on the front surface 49 of the back cover 45 facing the back surface 38 of the cone portion 32. In this embodiment, a plurality of shear grooves 70 are formed on the front surface of the back cover 45 at intervals in the circumferential direction. The plurality of shear grooves 70 are disposed opposite each other so as to be in sliding contact with the opposing surface of the blade portion 82 of each shear blade 80. As a result, the impurities E are sandwiched between the groove edge of each shear groove 70 and the edge of the blade portion 82, and the groove edge of each shear groove 70 and the edge of the blade portion 82 are in sliding contact with each other, thereby making it possible to shear the impurities E.

[0024] In this embodiment, the range where the shear blade 81 and the shear groove 70 face each other in the axial direction (hereinafter, also referred to as the "effective crushing range") is set only to the middle part near the center in the radial direction. That is, in the crushing section 80 of this embodiment, as shown in Fig. 2, the range where the shear blade 81 and the shear groove 70 face each other in the axial direction is vertically moved such that the shear blade 81 is located on the radial inside and the shear groove 70 is located on the radial outside.

[0025] Furthermore, the multiple shear grooves 70 in this embodiment are formed in the portion where the back surface 38 of the cone portion 32 of the suction screw 20 and the inner surface of the casing 40 (the front surface 49 of the back cover 45) face each other in the axial direction, so as to perform an impurity discharge function of guiding impurities E that have wrapped around the back surface of the cone portion 32 radially outward.

[0026] In particular, as shown in Fig. 3(b), the multiple shear grooves 70 of this embodiment are formed radially from the center 12c of the shaft 12 (eight locations in the example of the figure). The shear grooves 70 of this embodiment have a predetermined inclination θ inclined in a direction along the rotation direction R of the shaft 12 with respect to the rotation direction R of the shaft 12. When the shear grooves 70 are provided with an inclination θ in the crushing section 80 of this embodiment, the rotation direction of the shear blades 81 and the direction of the inclination θ coincide with each other, so that the impurities E are more easily discharged through the discharge grooves 70, which is more suitable for improving the discharge performance of the impurities E (see Fig. 3). Each shear groove 70 may be a communicating groove that is continuous in the radial direction, or a non-communicating groove that is interrupted midway in the radial direction. Each shear groove 70 may have a constant groove depth, or may be formed so that the groove depth gradually changes.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In contrast, according to the suction screw pump 10 of this embodiment, as described above, a crushing section 80 capable of crushing impurities E that have wrapped around the back surface 38 of the suction screw 20 is provided at the portion where the back surface of the suction screw 20 and the inner surface of the casing 40 face each other in the axial direction. Therefore, even if the impurities E sucked in from the suction port 46 end up on the back surface 48 of the suction screw 20 by a mechanism other than the impurities E getting caught on the tip 35 of the screw action portion, the impurities E can be crushed by the back surface 38 of the suction screw 20, thereby preventing or suppressing the problem of the impurities E getting stuck on the back surface 38 of the suction screw 20 and accumulating thereon [Invention 1].

[0031] In addition, in the suction screw pump 10 of this embodiment, the crushing section has a blade portion 82 which serves as a cutting blade provided on the back surface 38 of the suction screw 20, and is therefore suitable for crushing impurities E on the back surface 38 of the suction screw 20 by the rotating blade portion 82 [Invention 2].

[0032] In addition, in the suction screw pump 10 of this embodiment, the crushing section 80 has a shear groove 70 that is provided on the back cover 45 of the casing 40 opposite the blade portion 82 and cooperates with the blade portion 82 at the opening edge of its groove shape to shear the impurities E, making it suitable for crushing the impurities E by shearing [Invention 3].

[0033] In addition, in the suction screw pump 10 of this embodiment, the shear grooves 70 are formed radially from the center, which is suitable for shearing the impurities E and discharging the sheared impurities E [Invention 4].

[0034] In addition, in the suction screw pump 10 of this embodiment, the shear groove 70 has a predetermined inclination θ inclined in a direction along the rotational direction R with respect to the rotational direction R, which is more suitable for shearing the impurities E and discharging the sheared impurities E [Invention 5].

[0035] In addition, in the suction screw pump 10 of this embodiment, the shear groove 70 is a communicating groove that is continuous in the radial direction, or a non-communicating groove that is interrupted midway in the radial direction, which is more suitable for shearing the impurities E and discharging the sheared impurities E [Invention 6].

[0036] In addition, in the suction screw pump 10 of this embodiment, as shown in FIG. 2, the range in which the blade portion 82 of the shear blade 81 and the shear groove 70 face each other in the axial direction is limited to the middle portion near the center in the radial direction, so that the crushing portion 80 can stably exert the shearing function and is suitable for extending the life of the suction screw pump 10 [Invention 7].

[0037] Here, the reason for moving the "effective crushing range" up and down in this way and setting it only in the middle part will be explained. For example, if the "effective crushing range" is set over the entire radial direction, if the shear blade 81 comes into contact with the impurities E over the entire radial direction, the stress will be dispersed, the shearing function will not be fully exerted, and there will be a high possibility of being bitten. In contrast, with the "effective crushing range" of this embodiment, when large-sized impurities E flow into the crushing section 80, the shear blades 81 come into contact with the impurities E only in the middle part of the radial direction, concentrating stress and enabling the desired shearing function to be exerted, reducing the possibility of the impurities being caught, compared to when the "effective crushing range" is set over the entire radial direction. In addition, even if the impurities E are caught between the shear blades 81 and the shear grooves 70, the impact caused by the catch is small. Therefore, the crushing section can stably exert the shearing function, thereby achieving a long service life for the pump.

[0038] Furthermore, in the effective crushing range in this embodiment, since the region radially inward of the "effective crushing range" does not have the shear groove 70 at a position opposite the shear blade 81, the crushing effect itself is lower than that of the "effective crushing range". However, in the region radially lower half of the axial center line of the shaft 12, the shear groove 70 is intentionally not provided, so that the settled impurities E are easily introduced toward the crushing blade 80, and the impurities E that have settled in the crushing section 80 can be effectively brought into contact with the blade portion 82 of the crushing blade 80. Therefore, the engagement effect of the blade portion 82 of the shear blade 81 with the impurities E allows the impurities E to be smoothly introduced into the crushing blade 80 and effectively cut. In the region where only the shear grooves 70 are present radially outside the "effective crushing range", the discharge function of the impurities E is exerted by the discharge effect due to the groove shape of the shear grooves 70, and the discharge performance of the impurities E crushed by the crushing section 80 can be improved. Therefore, the crushing section 80 adopted in the suction screw pump 10 of this embodiment is extremely excellent as a crushing section that stably exerts the shearing function and is excellent in extending the life of the suction screw pump 10.

[0039] 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 38 of the suction screw 20. 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.

[0040] 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.

[0041] Furthermore, for example, in the above embodiment, an example was shown in which the crushing section 80 is equipped with a shear blade 81 and an opposing shear groove 70 and is configured to be able to crush impurities E by shearing, but the configuration of the crushing section 80 is not limited to only a configuration equipped with a shear blade 81 and an opposing shear groove 70.

[0042] 4, for example, pointed projections 32t having sharp tips can be provided in a plurality of locations spaced apart in the annular or circumferential direction on the outer circumferential side of the shear blades 81. By providing the pointed projections 32t in addition to the shearing action of the shear blades 81, the pointed projections 32t can prevent the intrusion of impurities E from the outer circumferential side to the inner circumferential side of the shear blades 81, and even if impurities E do intrude, the sharp tips of the pointed projections 32t can perform a cutting action, thereby strengthening the crushing function for impurities E and adding a function of preventing the intrusion of impurities E. In addition, in the region radially outside the "effective crushing range" where there is only the shear groove 70, only crushing (grinding) is performed between the corners of the shear groove 70 and the back surface of the suction screw 20. However, when a pointed protrusion 32t is provided, a crushing function is also exerted between the shear groove 70 and the pointed protrusion 32t. [Explanation of symbols]

[0043] 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 shear groove 80 Crushing Section 81 Shear blade 82 Blade (Cutting Blade) 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 R Rotation direction

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 crushing section capable of crushing impurities that have gotten around the back surface of the suction screw 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.

2. 2. The suction screw pump according to claim 1, wherein the crushing portion has a cutting blade provided on a back surface of the suction screw.

3. 3. The suction screw pump according to claim 2, wherein the crushing section has a shear groove provided on the back cover of the casing opposite the cutting blade and cooperating with the cutting blade at an opening edge of the groove to shear impurities.

4. 4. The suction screw pump according to claim 3, wherein a plurality of the shear grooves are formed radially from a center.

5. 4. The suction screw pump according to claim 3, wherein the shear groove has a predetermined inclination θ in a direction along the rotation direction with respect to the rotation direction.

6. 4. The suction screw pump according to claim 3, wherein the shear groove is a communicating groove which is continuous in the radial direction, or a non-communicating groove which is interrupted midway in the radial direction.

7. 4. The suction screw pump according to claim 3, wherein the cutting blade and the shear groove are set such that the range in which they face each other in the axial direction is limited to a midway portion near a center in the radial direction.

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