A vertically mounted rotary shell type rotary jet pump

Abstract

The invention discloses a vertically installed rotary shell type rotary spray pump, which belongs to the technical field of rotary spray pumps, and includes a rotary spray pump body, a pump shaft that rotates with the rotary spray pump body, and a rotary shell that is transmission-connected with a rotating shell. One end of the pump shaft passes through the suction cavity and then goes deep into the rotor cavity. The end face and side face of the pump shaft are respectively provided with a suction port and an exhaust port that are connected with the suction channel. The suction port and the exhaust port are respectively located in the rotor cavity and the suction cavity. An exhaust hole is also provided on the inner wall of the suction cavity. The exhaust port and the exhaust hole are respectively provided with a first one-way exhaust valve and a second one-way exhaust valve; a rotating drum is provided in the suction cavity to rotate around its axis, and a linear guide rail arranged along the axial direction is fixed to the inner side of the rotating drum. The linear guide rail is slidably matched with a piston along the axial direction, and a threaded hole that matches with the pump shaft thread is provided in the center of the piston; a stop control assembly connected with the rotating drum is provided on the rotary spray pump body. The invention does not require manual pump filling and is easy to use.

Description

Technical Field

[0001] The invention belongs to the technical field of pumps, and in particular relates to a vertically installed rotary shell type rotary jet pump. Background Art

[0002] The rotary jet pump is also called a rotary casing pump. It is a dynamic pump with a fixed pitot tube in the rotating cylindrical casing. This pump has the smallest flow and the highest head. Under the same conditions of use, it is smaller in size and lower in cost than a positive displacement pump or a multi-stage centrifugal pump. It has a smooth flow and no pulsation. There are no closely fitting parts in the liquid flow, so it will not wear out even if it runs dry. However, solid particles in the liquid will corrode the pitot tube, and the efficiency drops rapidly when there is gas in the liquid.

[0003] The rotary jet pump should be filled with water before starting. The existing pump filling process is usually achieved manually. Specifically, water or oil is manually filled into the inner cavity of the rotary jet pump before starting. This method has technical defects such as cumbersome use, low efficiency and safety. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a vertically installed volute-type rotary jet pump, which does not require manual priming and is easy to use.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention discloses a vertically installed volute-shell type rotary spray pump, comprising a rotary spray pump body, a pump shaft rotatably matched with the rotary spray pump body, and a rotary shell drivingly connected to the pump shaft. The rotary spray pump body is provided with a volute, and the rotary shell is arranged in a rotor cavity of the rotary spray pump body. The rotor cavity is simultaneously connected with a receiving channel and an inlet channel. A cylindrical air suction cavity is provided on the other side of the rotary spray pump body opposite to the rotor cavity. One end of the pump shaft passes through the air suction cavity and then penetrates into the rotor cavity. An air suction channel is provided in the center of the pump shaft, and the end face and side face of the pump shaft are respectively provided with air suction channels connected to the rotor cavity. The air intake port and the air exhaust port are connected to each other through the air intake passage, and the air intake port and the air exhaust port are respectively located in the rotor cavity and the air intake cavity. An exhaust hole is also provided on the inner wall of the air intake cavity, and a first one-way exhaust valve and a second one-way exhaust valve are respectively provided in the exhaust port and the exhaust hole. A rotating drum is provided in the air intake cavity for rotation around its axis, and a linear guide rail arranged along the axial direction is fixed to the inner side of the rotating drum. A piston is slidably fitted in the axial direction, and a threaded hole is provided in the center of the piston for fitting with the pump shaft thread. A stop control assembly connected with the rotating drum is provided on the rotary spray pump body.

[0007] Furthermore, a gear ring is provided on the outer side of the rotating drum, and the stop control assembly includes a gear, a first connecting rod, a first connecting rod support, a second connecting rod, a second connecting rod support, a third connecting rod, a third connecting rod support, a first spring and a floating trigger assembly. The first connecting rod support and the third connecting rod support are respectively slidably matched with the first connecting rod and the third connecting rod, and the gear is meshed with the gear ring. One end of the first connecting rod is fixedly connected to the gear, and the other end is hinged to one end of the second connecting rod. The middle part of the second connecting rod is hinged to the second connecting rod support to form a fulcrum, and the other end of the second connecting rod is hinged to one end of the third connecting rod. The distance from the fulcrum to the third connecting rod is smaller than the distance to the first connecting rod. The third connecting rod penetrates into the rotary spray pump body and cooperates with the floating trigger assembly in the volute case. The first spring is sleeved on the outer side of the first connecting rod, and the two ends of the first spring are respectively connected to the gear and the first connecting rod support.

[0008] Furthermore, the volute case includes a spiral inlet channel, and the diameter of the inlet channel gradually increases from the rotor chamber to the outlet of the volute case. The floating trigger assembly includes a mounting bracket, an arc guide rod, a float block, a second spring, and a limit plate. The mounting bracket is fixed in the inlet channel of the volute case, one end of the arc guide rod is fixed at the center of the mounting bracket, and the other end of the arc guide rod extends inward along the circumference of the volute case. An arc channel that slides with the arc guide rod is opened in the center of the float block, and a limit plate is fixed to the outer end of the arc guide rod, and the two ends of the second spring are respectively connected to the float block and the limit plate.

[0009] Furthermore, the floating block is conical, and the small end of the floating block faces the side where the mounting bracket is located.

[0010] Furthermore, a smooth cylinder section is arranged on the outer side of the rotating cylinder adjacent to the gear ring, a limiting ring is fixed on the outer end of the rotating cylinder, and a limiting groove cooperating with the limiting ring is opened on the inner wall of the suction cavity.

[0011] Furthermore, a sealing ring is arranged between the rotary spray pump body and the rotating drum, and an annular groove for installing the sealing ring is opened on the inner wall of the suction cavity.

[0012] Furthermore, a boss is formed at one end of the volute casing, a center hole is opened in the center of the boss, a packing is arranged between the center hole and the pump shaft, a pressure cover is threadedly connected to the inner side of the center hole, and the pressure cover presses the packing axially to the rotary spray pump body, and the center hole and the pump shaft are sealed by the packing.

[0013] Furthermore, a packing channel is radially opened on the volute, the outer end of the packing channel is detachably connected with a plug, and the inner end of the packing channel extends into the installation space of the packing.

[0014] The beneficial effects of the present invention are:

[0015] The present invention is a vertically installed rotary shell type rotary spray pump. Before the device is started, the outer wall gear ring of the rotating drum is engaged by the gear, and the linear guide fixed to the inner wall of the rotating drum does not rotate. Since the piston is slidably matched with the linear guide, and the pump shaft is threadedly matched with the piston, when the motor drives the pump shaft to rotate, the pump shaft can drive the piston to move along the axis, and the suction cavity on the right side of the piston generates negative pressure, which can suck the air at the right end of the suction channel into the suction cavity, and then discharge it through the exhaust hole, thereby playing the role of automatically discharging the air in the rotor cavity. The device of the present invention does not need to be manually primed, and is more convenient to use.

[0016] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0018] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0019] Figure 2 for Figure 1 A magnified view at point A;

[0020] Figure 3 for Figure 1 Enlarged view at B;

[0021] Figure 4 is a cross-sectional view of the volute;

[0022] Figure 5 This is the appearance diagram of the spiral casing.

[0023] The markings in the accompanying drawings are as follows: rotary jet pump body 1, pump shaft 2, rotating shell 3, volute 4, rotor chamber 5, receiving channel 6, inlet channel 7, suction chamber 8, suction channel 9, suction port 10, exhaust port 11, exhaust hole 12, first one-way exhaust valve 13, second one-way exhaust valve 14, rotating cylinder 15, linear guide 16, piston 17, threaded hole 18, stop control assembly 19, gear ring 20, gear 21, first connecting rod 22, first connecting rod support 2 3. second connecting rod 24, second connecting rod support 25, third connecting rod 26, third connecting rod support 27, first spring 28, floating trigger assembly 29, inlet channel 30, mounting bracket 31, arc guide rod 32, floating block 33, second spring 34, limit plate 35, arc channel 36, light tube section 37, limit ring 38, limit groove 39, sealing ring 40, annular groove 41, boss 42, packing 43, pressure cover 44, packing channel 45, plug 46. DETAILED DESCRIPTION

[0024] like Figures 1 to 5 As shown, a vertically mounted swirl shell type swirl pump of the present invention comprises a swirl shell pump body 1, a pump shaft 2 which rotates with the swirl shell pump body 1, and a rotating shell 3 which is transmission-connected with the pump shaft 2. The swirl shell pump body 1 is vertically mounted, and the pump shaft 2 is driven to rotate by a belt. The pump shaft 2 is connected and matched at the center of the rotating shell 3, crosses the swirl shell pump body 1 and rotates and seals with the swirl shell pump body 1, and a swirl shell 4 is installed on the swirl shell pump body 1. Specifically, during operation, water enters the rotor cavity 5 from the inlet channel, and the rotating shell 3 drives the water to move centrifugally, and the liquid increases its pressure and speed due to the centrifugal force. The opening of the receiving channel is placed close to the outer wall of the rotating shell 3, so that most of the kinetic energy of the liquid is converted into static pressure energy, and then returns to the center of the pump and is discharged from the receiving channel 6. The pressure near the rotating shell 3 is reduced, and a low-pressure area is formed near the rotating shaft. Under the action of atmospheric pressure, the water outside opens the bottom valve and enters the pump from the water inlet pipe. The water rushing in is thrown out again during the high-speed rotation of the rotating shell 3.

[0025] Specifically, the rotating shell 3 is disposed in the rotor cavity 5 of the rotary jet pump body 1, and is used to provide power for accelerating the water. The rotor cavity 5 is also connected to a receiving channel 6 and an inlet channel 7, which are used for water discharge and water intake, respectively. In the present invention, a cylindrical air suction cavity 8 is provided on the other side of the rotary jet pump body 1 opposite to the rotor cavity 5, and the axis of the air suction cavity 8 coincides with the axis of the pump shaft 2. One end of the pump shaft 2 passes through the air suction cavity 8 and penetrates into the rotor cavity 5, and the other end is connected to the motor and driven to rotate by the motor.

[0026] Different from the existing equipment, the center of the pump shaft 2 of the present invention is provided with an air intake channel 9, which extends along the axial direction of the pump shaft 2. The end face and side face of the pump shaft 2 are respectively provided with an air intake port 10 and an air exhaust port 11 connected with the air intake channel 9. The air intake port 10 and the air exhaust port 11 are respectively located in the rotor cavity 5 and the air intake cavity 8. The air intake port 10 is used to suck the air in the rotor cavity 5 into the air intake channel 9, and then discharge it into the air intake cavity 8 through the air exhaust port 11 of the air intake channel 9. The inner wall of the air intake cavity 8 is also provided with an air exhaust hole 12, and the air is discharged from the air exhaust hole 12. The first one-way exhaust valve 13 and the second one-way exhaust valve 14 are respectively provided in the exhaust port 11 and the exhaust hole 12, which can play the role of one-way exhaust and ensure the smooth initial air intake of the device of the present invention.

[0027] In the air suction chamber 8 of the present invention, a rotating drum 15 is arranged to rotate around its axis. The outer walls at both ends of the rotating drum 15 are smooth enough to slide and seal with the inner wall of the air suction chamber 8. A linear guide rail 16 arranged along the axial direction is fixed to the inner side of the rotating drum 15. The linear guide rail 16 slides along the axial direction and cooperates with a piston 17. The linear guide rail 16 and the outer side of the piston 17 are connected in a key-like manner. The two can be relatively displaced in the axial direction, but they rotate synchronously in the circumferential direction. A threaded hole 18 that is threadedly matched with the pump shaft 2 is provided at the center of the piston 17; a stop control assembly 19 connected to the rotating drum 15 is provided on the rotary spray pump body 1, and an opening is provided on the rotary spray pump body 1 corresponding to the rotating drum 15 so that the stop control assembly 19 cooperates with the rotating drum 15 to stop or release it.

[0028] In this embodiment, a gear ring 20 is provided on the outer side of the rotating drum 15, and the gear ring 20 can be provided separately or can be a gear directly and integrally provided in the middle of the outer side of the rotating drum 15. The stop control assembly 19 of the present invention comprises a gear 21, a first connecting rod 22, a first connecting rod support 23, a second connecting rod 24, a second connecting rod support 25, a third connecting rod 26, a third connecting rod support 27, a first spring 28 and a floating trigger assembly 29, the gear 21 is located on the outer side of the rotary spray pump body 1, the gear 21 is meshed with the gear ring 20, and the opening on the rotary spray pump body 1 provides a space for the gear 21 to mesh with the gear ring 20.

[0029] The first connecting rod support 23, the second connecting rod support 25 and the third connecting rod support 27 of the present invention are all fixed on the outer surface of the rotary spray pump body 1, the first connecting rod support 23 and the third connecting rod support 27 are respectively slidably matched with the first connecting rod 22 and the third connecting rod 26, the first connecting rod 22 and the third connecting rod 26 can be displaced along the axial direction of the pump shaft 2, one end of the first connecting rod 22 is fixedly connected to the gear 21, and the other end is hinged to one end of the second connecting rod 24, the middle part of the second connecting rod 24 is hinged to the second connecting rod support 25 to form a fulcrum, the other end of the second connecting rod 24 is hinged to one end of the third connecting rod 26, the distance from the fulcrum to the third connecting rod 26 is less than the distance to the first connecting rod 22, the third connecting rod 26 penetrates into the rotary spray pump body 1 and cooperates with the floating trigger assembly 29 in the volute 4, the first spring 28 is sleeved on the outside of the first connecting rod 22, and the two ends of the first spring 28 are respectively connected to the gear 21 and the first connecting rod support 23. The present invention uses the second connecting rod 24 as a lever to amplify the displacement length of the third connecting rod 26, so that the gear 21 can be more easily displaced in the axial direction, which can facilitate the meshing and loosening operations between the gear 21 and the rotating drum 15. The present invention provides a first spring 28 to provide a restoring force for the gear 21, so that the gear 21 and the gear ring 20 can be meshed again after the device is used.

[0030] In this embodiment, the volute 4 includes a spiral inlet channel 7, and the diameter of the inlet channel 7 gradually increases from the rotor chamber 5 to the inlet of the volute 4. The floating trigger assembly 29 includes a mounting bracket 31, an arc-shaped guide rod 32, a float 33, a second spring 34, and a limit plate 35. The mounting bracket 31 is fixed in the inlet channel 7 of the volute 4, one end of the arc-shaped guide rod 32 is fixed at the center of the mounting bracket 31, and the other end of the arc-shaped guide rod 32 extends inward along the circumference of the volute 4. An arc-shaped channel 36 that slides with the arc-shaped guide rod 32 is opened in the center of the float 33, and a limit plate 35 is fixed to the outer end of the arc-shaped guide rod 32. The two ends of the second spring 34 are respectively connected to the float 33 and the limit plate 35.

[0031] The working process of the present invention is as follows:

[0032] 1. Before the device is started, the outer wall gear ring 20 of the rotating drum 15 is engaged by the gear 21 in normal state. After the rotating drum 15 is limited by the gear 21, the linear guide 16 fixed on the inner wall of the rotating drum 15 will not rotate. Since the piston 17 on the inner side of the suction chamber 8 is axially slidably matched with the linear guide 16, and the pump shaft 2 is threadedly matched with the piston 17, when the motor drives the pump shaft 2 to rotate, under the circumferential limit of the linear guide 16, the pump shaft 2 can drive the piston 17 to move along the axis. When the piston 17 moves to the left, the space of the suction chamber 8 on the right side of the piston 17 becomes larger, thereby generating negative pressure, which can suck the air at the right end of the suction channel 9 into the suction chamber 8, and then discharge it through the exhaust hole 12, thereby playing the role of automatically discharging the air in the rotor chamber 5.

[0033] 2. When the air is exhausted, water replaces the air and enters the suction chamber 8 to exhaust the remaining air. At the same time, the water in the rotor chamber 5 is filled and gradually fills the inlet channel 7 of the volute 4. Under the impact of the water, the float 33 in the inlet channel 7 moves along the arc guide rod 32. After breaking free from the restraint of the second spring 34, the float 33 contacts the inner end of the third connecting rod 26 to drive the third connecting rod 26 to move. The outer end of the third connecting rod 26 drives the first connecting rod 22 to move through the second connecting rod 24, so that the first connecting rod 22 can drive the gear 21 to move along the axial direction of the pump shaft 2, so that the gear 21 and the ring gear 20 are disengaged. At this time, the drum 15 can rotate freely, and the drum 15, the linear guide 16 and the piston 17 can rotate together with the pump shaft 2. The piston 17 no longer generates negative pressure, and the exhaust check valve is closed under the action of prestress, and no water is sucked out, which plays a role of automatically stopping the suction.

[0034] 3. When the whole device is finished working, the gear 21 returns to its original position under the action of the first spring 28, and the pump shaft 2 can be manually rotated in the opposite direction so that the piston 17 is close to the inner wall of the right end of the suction chamber 8, which facilitates the smooth progress of the next suction cycle.

[0035] In this embodiment, the float 33 is conical, and the small end of the float 33 is toward the side where the mounting bracket 31 is located. By setting the conical float 33, when the float 33 is subjected to the buoyancy of the center of the volute 4, the conical surface can contact the inner end of the third connecting rod 26, and the conical surface is gradually pressed against the inner end of the third connecting rod 26, so that the action is smoother.

[0036] In this embodiment, a smooth cylinder section 37 is provided on the outer side of the rotating drum 15 adjacent to the gear ring 20. When the gear 21 is pushed to the left by one end, the gear 21 is located at the position of the smooth cylinder section 37 and will not mesh with the gear ring 20. Avoid affecting the rotating drum 15. A limiting ring 38 is fixed to the outer end of the rotating drum 15, and a limiting groove 39 that cooperates with the limiting ring 38 is provided on the inner wall of the suction chamber 8. The limiting ring 38 and the limiting groove 39 cooperate to limit the axial direction of the rotating drum 15. A sealing ring 40 is provided between the rotary spray pump body 1 and the rotating drum 15, and an annular groove 41 for installing the sealing ring 40 is provided on the inner wall of the suction chamber 8, which can be used to seal between the rotating drum 15 and the rotary spray pump body 1.

[0037] In this embodiment, a boss 42 is formed at one end of the volute 4, a center hole is provided at the center of the boss 42, a packing 43 is provided between the center hole and the pump shaft 2, a gland 44 is threadedly connected to the inner side of the center hole, the gland 44 presses the packing 43 axially against the rotary jet pump body 1, and the center hole and the pump shaft 2 are sealed by the packing 43, which can increase the sealing effect between the volute 4 and the pump shaft 2. A packing channel 45 is radially provided on the volute 4, a plug 46 is detachably connected to the outer end of the packing channel 45, and the inner end of the packing channel 45 extends into the installation space of the packing 43. By providing the packing channel 45, the packing 43 in the installation space can be supplemented to improve the sealing effect between the volute 4 and the pump shaft 2, and avoid water leakage or air leakage.

[0038] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A vertically mounted volute-type jet pump, comprising a jet pump body (1), a pump shaft (2) rotatably matched with the jet pump body (1), and a rotating shell (3) drivingly connected to the pump shaft (2), wherein a volute (4) is mounted on the jet pump body (1), the rotating shell (3) is arranged in a rotor cavity (5) of the jet pump body (1), and the rotor cavity (5) is simultaneously connected to a receiving channel (6) and an inlet channel (7), characterized in that: A cylindrical air suction chamber (8) is provided on the other side of the rotary jet pump body (1) opposite to the rotor chamber (5). One end of the pump shaft (2) passes through the air suction chamber (8) and then penetrates into the rotor chamber (5). An air suction passage (9) is provided at the center of the pump shaft (2). An air suction port (10) and an air exhaust port (11) which are connected to the air suction passage (9) are provided on the end surface and the side surface of the pump shaft (2). The air suction port (10) and the air exhaust port (11) are respectively located in the rotor chamber (5) and the air suction chamber (8). An air exhaust hole (12) is also provided on the inner wall of the air suction chamber (8). 11) and the exhaust hole (12) are respectively provided with a first one-way exhaust valve (13) and a second one-way exhaust valve (14); a rotating drum (15) is arranged in the suction chamber (8) to rotate around its axis, a linear guide rail (16) arranged along the axial direction is fixed on the inner side of the rotating drum (15), a piston (17) is slidably matched with the linear guide rail (16) along the axial direction, and a threaded hole (18) is provided at the center of the piston (17) to be threadedly matched with the pump shaft (2); a stop control component (19) connected to the rotating drum (15) is provided on the rotary spray pump body (1); a gear ring is provided on the outer side of the rotating drum (15) (20), the stop control assembly (19) comprises a gear (21), a first connecting rod (22), a first connecting rod support (23), a second connecting rod (24), a second connecting rod support (25), a third connecting rod (26), a third connecting rod support (27), a first spring (28) and a floating trigger assembly (29), the first connecting rod support (23) and the third connecting rod support (27) are respectively slidably matched with the first connecting rod (22) and the third connecting rod (26), the gear (21) is meshed with the ring gear (20), one end of the first connecting rod (22) is fixedly connected to the gear (21), and the other end is fixedly connected to the second One end of the connecting rod (24) is hinged, the middle part of the second connecting rod (24) is hinged to the second connecting rod support (25) to form a fulcrum, the other end of the second connecting rod (24) is hinged to one end of the third connecting rod (26), the distance from the fulcrum to the third connecting rod (26) is smaller than the distance to the first connecting rod (22), the third connecting rod (26) penetrates into the rotary spray pump body (1) and cooperates with the floating trigger component (29) in the volute case (4), the first spring (28) is sleeved on the outside of the first connecting rod (22), and the two ends of the first spring (28) are respectively connected to the gear (21) and the first connecting rod support (23).

2. A vertically mounted volute-type rotary jet pump according to claim 1, characterized in that: The volute (4) comprises a spiral inlet passage (7), the diameter of which gradually increases from the rotor chamber (5) to the outlet of the volute (4). The floating trigger assembly (29) comprises a mounting bracket (31), an arc-shaped guide rod (32), a floating block (33), a second spring (34), and a limit plate (35). The mounting bracket (31) is fixed in the inlet passage (7) of the volute (4), one end of the arc-shaped guide rod (32) is fixed at the center of the mounting bracket (31), the other end of the arc-shaped guide rod (32) extends inwardly along the circumference of the volute (4), an arc-shaped hole (36) for slidingly cooperating with the arc-shaped guide rod (32) is opened at the center of the floating block (33), the outer end of the arc-shaped guide rod (32) is fixed with a limit plate (35), and the two ends of the second spring (34) are respectively connected to the floating block (33) and the limit plate (35).

3. A vertically mounted volute-type rotary jet pump according to claim 2, characterized in that: The floating block (33) is conical, and the small end of the floating block (33) faces the side where the mounting bracket (31) is located.

4. A vertically mounted volute-type rotary jet pump according to claim 1, characterized in that: A smooth cylinder section (37) is arranged on the outer side of the rotating cylinder (15) adjacent to the gear ring (20), a limiting ring (38) is fixed to the outer end of the rotating cylinder (15), and a limiting groove (39) cooperating with the limiting ring (38) is opened on the inner wall of the suction cavity (8).

5. A vertically mounted volute-type rotary jet pump according to claim 1, characterized in that: A sealing ring (40) is arranged between the rotary spray pump body (1) and the rotating drum (15), and an annular groove (41) for installing the sealing ring (40) is provided on the inner wall of the air suction cavity (8).

6. A vertically mounted volute-type rotary jet pump according to any one of claims 1 to 5, characterized in that: A boss (42) is formed at one end of the volute case (4), a center hole is opened at the center of the boss (42), a filler (43) is arranged between the center hole and the pump shaft (2), a pressure cover (44) is threadedly connected to the inner side of the center hole, and the pressure cover (44) presses the filler (43) axially against the volute pump body (1), and the center hole and the pump shaft (2) are sealed by the filler (43).

7. A vertically mounted volute-type rotary jet pump according to claim 6, characterized in that: A packing passage (45) is radially opened on the volute (4), the outer end of the packing passage (45) is detachably connected to a plug (46), and the inner end of the packing passage (45) extends into the installation space of the packing (43).

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