JP7770992B2 - pump - Google Patents

Description

The present invention relates to a pump.

Patent Document 1 discloses a pump in which a bypass pipe is connected to the pump casing and an on-off valve is placed in the bypass pipe, and the on-off valve is opened during maintenance operations that do not involve drainage, allowing a portion of the pumped water to be returned to the suction tank through the bypass pipe.

Patent No. 5063744

The pump in Patent Document 1 uses an electric butterfly valve as the on-off valve, which does not require a drive source, and does not take into consideration automatic opening and closing of the valve depending on the operating state.

The objective of this invention is to provide a pump that uses a valve that does not require a drive source and can automatically open and close the valve depending on the operating state.

The present invention provides a pump having a cylindrical pump casing partially disposed within a suction tank, an impeller rotatably disposed within the pump casing for discharging water from the suction tank, a bypass pipe disposed outside the pump casing and branched off from the pump casing downstream of the impeller for allowing a portion of the pumped water discharged through the pump casing to flow out of the pump casing, and a rotating shaft rotatably supported by the bypass pipe, and which blocks the outflow of the pumped water when the pressure within the pump casing becomes higher than the pressure within the bypass pipe. Provided is a pump comprising: a flap valve that can be rotated in a direction away from the pump casing from a closed state to an open state that allows the outflow of the pumped water; and an adjustment mechanism that is attached to the rotating shaft and adjusts the force that maintains the flap valve in the closed state, at least one end of the rotating shaft penetrating the bypass pipe and protruding to the outside, an arm being provided at the one end of the rotating shaft, and the adjustment mechanism comprising a biasing member that is connected to the arm and constituted by a constant-load spiral spring that biases the flap valve to a closed position via the arm and the rotating shaft .

A flap valve is attached to the bypass pipe, which can rotate from a closed position to an open position when the pressure inside the pump casing exceeds the pressure inside the bypass pipe. The pressure inside the bypass pipe is higher than the pressure inside the pump casing during normal operation for the purpose of drainage, and lower than the pressure inside the pump casing during maintenance operation for non-drainage purposes. As a result, the flap valve is closed during normal operation and open during maintenance operation. The flap valve does not require a drive source to switch between open and closed states, reducing the running costs of the pump equipment. Furthermore, the rotating shaft of the flap valve is equipped with an adjustment mechanism for adjusting the force that keeps the flap valve closed, allowing the pressure difference (timing) at which the flap valve opens and closes to be adjusted. This allows the flap valve to reliably open and close automatically according to the operating state, switching to a closed state during normal operation and an open state during maintenance operation.

The pump of the present invention uses a valve that does not require a driving source and can automatically open and close the valve depending on the operating conditions.

1 is a cross-sectional view of a pump according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of part II in FIG. 1 . FIG. 3 is an enlarged cross-sectional view of part III in FIG. 2 . FIG. 3 is an enlarged cross-sectional view of a portion IV in FIG. 2 . FIG. 5 is a right side view of FIG. 4 . FIG. 6 is a partial cross-sectional view of FIG. 5 . FIG. 4 is a diagram showing the relationship between an arm, a weight, and a spiral spring. FIG. 10 is a diagram showing the spring material in a non-connected state. Graph showing the relationship between load and deflection of spring material. FIG. Graph showing changes in pump performance.

The following describes an embodiment of the present invention with reference to the drawings.

Referring to Figure 1, a vertical pump (pump) 10 according to an embodiment of the present invention is fixed to the installation floor 1 of a drainage pumping station and discharges rainwater and other water that has flowed into a suction tank 2 located below the installation floor 1 downstream.

The vertical pump 10 comprises a pump casing 12, a rotating shaft 15, an impeller 16, a motor 17, and a control unit 18. The control unit 18 can perform normal operation for the purpose of draining water, and maintenance operation for the purpose of not draining water. Maintenance operation is performed for the purpose of maintaining the performance of the vertical pump 10, such as when normal operation has not been performed for an extended period of time, and the motor 17 (impeller 16) is rotated at a slower speed (lower rotational frequency) than during normal operation to minimize the discharge volume. This maintenance operation includes mini-flow operation, which is performed with the gate valve 6 open, and shut-off operation, which is performed with the gate valve 6 closed.

In the vertical pump 10 of this embodiment, a bypass pipe 20 is branched off and connected to the pump casing 12, allowing a portion of the pumped water to flow out of the pump casing 12. A flap valve 35, which does not require a drive source, is attached to the bypass pipe 20, allowing a portion of the pumped water to flow out only during maintenance operation. An adjustment mechanism 50 is provided on the bypass pipe 20 to adjust the timing of switching the open/close state of the flap valve 35.

The configuration of the vertical pump 10 of this embodiment is described in detail below.

Referring to Figure 1, the pump casing 12 is inserted into a through-hole formed in the installation floor 1 and fixed to the installation floor 1. The pump casing 12 comprises a lift pipe 13 disposed within the suction tank 2 and a discharge elbow 14 disposed on the installation floor 1. The lift pipe 13 extends vertically and comprises suction ports 13a disposed at intervals on the bottom 3 of the suction tank 2. The discharge elbow 14 is a curved pipe whose axis is bent 90 degrees and is connected to the discharge pipe 5 equipped with a gate valve 6 (which in this embodiment is normally closed and can be opened and closed manually).

The rotating shaft 15 passes through the discharge elbow 14 and is arranged along the axis A of the riser pipe 13. The rotating shaft 15 is rotatably supported by a bearing arranged inside the riser pipe 13.

The impeller 16 is attached to the lower end of the rotating shaft 15 so that it is located at the bottom of the lifting pipe 13. The impeller 16 rotates integrally with the rotating shaft 15 and discharges water from the suction tank 2 through the pump casing 12.

The motor 17 is a drive source mechanically connected to the upper end of the rotating shaft 15 located outside the pump casing 12. The motor 17 is electrically connected to the control unit 18 via a drive circuit, and the control unit 18 rotates the impeller 16 via the rotating shaft 15 at a predetermined rotation speed.

The control unit 18 is configured using a personal computer. However, the control unit 18 may also be configured using a single or multiple microcomputers and other electronic devices. The control unit 18 determines whether to perform normal operation, maintenance operation, or operation shutdown based on the water level detection results, for example, from a water level sensor disposed in the suction tank 2, and controls the motor 17 so that the rotating shaft 15 rotates at a predetermined rotation speed depending on the operation to be performed. The control unit 18 stops the rotation of the motor 17 when operation is shutdown, rotates the motor 17 at a constant speed to minimize the discharge volume in maintenance operation, and rotates the motor 17 at a constant speed higher than that in maintenance operation in normal operation.

Continuing to refer to Figure 1, two bypass pipes 20 are provided at opposing positions outside the lift pipe 13. However, the number of bypass pipes 20 may be one, or three or more. Each bypass pipe 20 includes a horizontal pipe (first pipe) 21 branching off from the discharge elbow 14 downstream (above) of the impeller 16, and a vertical pipe (second pipe) 22 branching off from the horizontal pipe 21.

Referring to Figure 2, the horizontal pipe 21 has an inner end 21a connected to the discharge elbow 14 and an outer end (end) 21b remote from the discharge elbow 14. It is a straight pipe extending perpendicular to the axis A of the pumping pipe 13 (see Figure 1). The interior of the horizontal pipe 21 and the interior of the pump casing 12 are spatially connected, allowing a portion of the pumped water in the pump casing 12 to flow into the horizontal pipe 21. The inner diameter of the horizontal pipe 21 is smaller than the inner diameter of the pump casing 12 (e.g., by 30 to 40%). However, the extension direction of the horizontal pipe 21 does not have to be orthogonal in the strict geometric sense, as long as the interior of the pump casing 12 can be seen through the opening of the inner end 21a when viewed from the opening of the outer end 21b. The horizontal pipe 21 may also be a curved pipe.

Referring to Figure 3, a cylindrical connection portion 21c that connects to the vertical pipe 22 protrudes downward from the horizontal pipe 21. A cylindrical portion 21d that protrudes upward is provided on the horizontal pipe 21 at a position opposite the connection portion 21c. The cylindrical portion 21d is covered by a transparent lid 24. This allows the interior of the vertical pipe 22 to be seen through the lid 24.

Referring to Figures 3 and 6, the horizontal pipe 21 is provided with a bearing portion 21e, an insertion portion 21f, and a fixed valve seat 39 for mounting the flap valve 35. The specific configuration of these components will be described in detail later.

Referring to FIG. 1, the vertical pipe 22 is a straight pipe that extends along the lift pipe 13. The vertical pipe 22 has an upper end (first end) 22a connected to the connection portion 21c of the horizontal pipe 21, and a lower end (second end) 22b disposed within the suction tank 2. The interior of the vertical pipe 22 is spatially connected to the interior of the horizontal pipe 21, and has a length that allows water that flows into the horizontal pipe 21 to flow out from the lower end 22b to the bottom 3 of the suction tank 2. However, the vertical pipe 22 may be of any length that allows water to flow into the suction tank 2, or may be a curved pipe. The diameter of the vertical pipe 22 may be different from the diameter of the horizontal pipe 21 as long as it allows water to flow into the suction tank 2.

An endless ring-shaped pipe 23 that surrounds the lift pipe 13 is connected to the lower ends 22b of the two vertical pipes 22. The ring-shaped pipe 23 is annular and centered on the axis A of the lift pipe 13, and is disposed between the suction port 13a and the impeller 16. The ring-shaped pipe 23 is provided with a plurality of nozzles 23a spaced apart circumferentially, which discharge water toward the bottom 3 of the suction tank 2. This allows the water discharged from the nozzles 23a to scrape up sludge on the bottom 3 of the suction tank 2 and discharge it together with the water inside the suction tank 2. Note that the vertical pipes 22 may not be provided with ring-shaped pipes 23, and instead the nozzles 23a may be provided at the lower ends 22b of the vertical pipes 22, or the lower ends 22b of the vertical pipes 22 may be open inside the suction tank 2.

Referring to Figures 3 and 5, the outer end 21b of the horizontal pipe 21 is closed by an end plate 25 to which an openable and closable door 26 is attached.

The end plate 25 is a metal ring with an opening 25a. The end plate 25 is attached liquid-tight to the outer end 21b of the horizontal pipe 21, and the opening 25a is formed so that its center coincides with the axis of the horizontal pipe 21. The end plate 25 is provided with bolt holes (not shown) for fastening the door 26 in the closed state, and a retaining portion 28 for holding the door 26 in the open state. The retaining portion 28 consists of a plate attached below the opening 25a and extends along the installation floor 1 (see Figure 1).

The door 26 is disc-shaped with a diameter larger than the diameter of the opening 25a, and when closed, the gap between it and the end plate 25 is sealed by a sealing member (not shown). The door 26 is made of a transparent plate with translucency, allowing the inside of the horizontal pipe 21 to be seen from the outside through the opening 25a. Therefore, the open/closed state of the flap valve 35 can be easily confirmed through the door 26 during both normal operation and maintenance operation. Furthermore, during maintenance operation, the return state of a portion of the pumped water can be easily confirmed through the door 26. However, as long as only the portion of the door 26 corresponding to the opening 25a is translucent, the other portions may be non-translucent and opaque.

A hinge 27 is attached to the lower end of the door 26, and a pair of eyebolts (fastening members) 29 are attached circumferentially spaced apart on the upper side opposite the hinge 27. As shown most clearly in Figure 3, the hinge 27 is attached to a retaining portion 28. When the hinge 27 abuts against the retaining portion 28, the door 26 is held in an open position (open position) extending along the axis of the horizontal piping 21. This allows the door 26 to be used as a support for inserting a measuring instrument such as an endoscope during inspection inside the pump casing 12. The eyebolt 29 is attached to the door 26 via a bracket 30. The door 26 is maintained in the closed state by rotating the door 26 from the open position to the closed position and tightening the eyebolt 29 into the bolt hole.

Referring to Figure 1, the flap valve 35 opens and closes based on the difference between the pressure P inside the discharge elbow 14, the pressure Pd outside the flap valve 35 in the bypass pipe 20 outside the discharge elbow 14 (hereinafter referred to as the "pressure inside the horizontal pipe 21"), and the pressure Ps inside the suction tank 2. Referring to Figures 3 and 6, the flap valve 35 comprises a valve body 36 having a rotating shaft 37 and a fixed valve seat 39 provided inside the horizontal pipe 21.

The valve element 36 can rotate integrally with a horizontally extending rotary shaft 37 via an arm. The rotary shaft 37 is inserted into an insertion portion 21f formed in the horizontal pipe 21 and supported by a bearing portion 21e. The bearing portion 21e and insertion portion 21f are located at an upper portion of the horizontal pipe 21, closer to the inner end 21a than the connection portion 21c. The bearing portion 21e is a recess that recesses radially outward from the internal space of the horizontal pipe 21. The insertion portion 21f is located on the opposite side of the axis of the horizontal pipe 21 from the bearing portion 21e and is a hole that penetrates from the internal space of the horizontal pipe 21 to the outside. A seal member 40 is attached to the insertion portion 21f to seal the rotary shaft 37. The portion of the rotary shaft 37 protruding from the insertion portion 21f is supported by a bearing member 42 equipped with a ball bearing 41.

Referring to Figure 3, the surface of the valve disc 36 that faces the discharge elbow 14 in the closed state is provided with an annular movable valve seat 38. An annular fixed valve seat 39 is provided in the horizontal pipe 21 below the bearing portion 21e and insertion portion 21f and on the discharge elbow 14 side of the valve disc 36 in the closed state. Rotation of the valve disc 36 away from the discharge elbow 14 (valve opening) separates the movable valve seat 38 from the fixed valve seat 39, and rotation of the valve disc 36 toward the discharge elbow 14 (valve closing) presses the movable valve seat 38 against the fixed valve seat 39.

During normal operation, the pressure P in the discharge elbow 14 is lower than the pressure Pd in the side pipe 21 and the pressure Ps in the suction tank 2 (P<Pd≦Ps). This causes the flap valve 35 to rotate to the closed position shown by the solid line in Figure 3, with the movable valve seat 38 pressed against the fixed valve seat 39, blocking the pumping of water from the discharge elbow 14 to the side pipe 21 (closed state). During controlled operation, not only during shut-off operation but also during mini-flow operation, the pressure P in the discharge elbow 14 is higher than the pressure Pd in the side pipe 21 and the pressure Ps in the suction tank 2 (P>Pd≧Ps). This causes the flap valve 35 to rotate to the open position shown by the dashed line in Figure 3 so that the movable valve seat 38 moves away from the fixed valve seat 39, allowing some of the pumped water to flow into the discharge elbow 14 (open state). The open state refers not only to the state rotated to the open position shown by the dashed line in Figure 3, but also to a state in which the movable valve seat 38 of the flap valve 35 is separated from the fixed valve seat 39, allowing pumped water to flow into the discharge elbow 14. The opening angle of the flap valve 35, which is the valve opening degree, varies depending on the difference between the pressure P in the discharge elbow 14 and the pressure Pd in the horizontal pipe 21.

Referring to Figures 4 and 6, the adjustment mechanism 50 is provided to adjust the force that maintains the flap valve 35 in a closed state, and is attached to the portion of the rotating shaft 37 that protrudes outward from the horizontal pipe 21 through the insertion portion 21f. The adjustment mechanism 50 includes an arm 51 attached to the rotating shaft 37, and a spiral spring 52 and weight 56 attached to the arm 51. A damper 57 is also attached to the arm 51.

The arm 51 is attached to the outer end of the rotary shaft 37 and is a rod extending away from the rotary shaft 37. It has a first portion 51a that protrudes to the right from the rotary shaft 37 in FIG. 4 and a second portion 51b that protrudes to the left from the rotary shaft 37 in FIG. 4. The arm 51 extends horizontally when the flap valve 35 is in the closed position, and can be manually operated counterclockwise in FIG. 4 to rotate the flap valve 35 to the open position. When the flap valve 35 is in the closed position, the flap valve 35 abuts against the fixed valve seat 39, so the arm 51 cannot be operated clockwise in FIG. 4. When the arm 51 is opened and then released, the weight of the flap valve 35, the weight of the arm 51, the biasing force of the spiral spring 52, and the weight of the weight 56 cause the flap valve 35 to rotate to the closed position.

Referring to Figures 4 and 7, the spiral spring 52 is connected to the first portion 51a of the arm 51 via the weight 56, and is a biasing member that biases the flap valve 35 to the closed position via the arm 51 and the rotating shaft 37. The spiral spring 52 is of a constant load type and includes a strip-shaped spring material 53 mechanically connected to the weight 56, and a winding member 54 that winds up the spring material 53 so that it can be unwound.

Referring to Figure 8, the spring material 53 has a tip portion 53a on the tip side and a linear portion 53b on the base side connected to the tip portion 53a. The tip portion 53a of the spring material 53 has a connection hole 53c for connection to the weight 56. Referring to Figure 9, the relationship between the load (returning force) and the unwinding length at the tip portion 53a is nonlinear (initial deflection e). Therefore, when the unwinding length from the winding member 54 falls within the range of the tip portion 53a, the load increases as unwinding from the winding member 54 progresses. Therefore, the relationship between the load and the unwinding length at the linear portion 53b is linear (constant). Therefore, once the unwinding length from the winding member 54 reaches the linear portion 53b, the load remains constant even if unwinding from the winding member 54 progresses further. If the diameter of the winding portion 54a, which will be described later, increases, the length of the tip portion 53a (the portion where initial deflection e occurs) also increases. For example, if the diameter of the winding portion 54a is 100 mm, the length of the tip portion 53a will be approximately 30 mm to 330 mm. However, the length of the tip portion 53a (the portion where the initial deflection e occurs) can vary depending on the shape and material of the spring material 53.

Referring to Figures 7 and 8, the winding member 54 is a bobbin capable of spirally winding the spring material 53, and is provided with a mounting flange 54b at one end of a cylindrical winding portion 54a for mounting to the horizontal pipe 21. The center C1 of the winding portion 54a and the center C2 of the mounting flange 54b are eccentric to each other. The mounting flange 54b has multiple (four in this embodiment) mounting holes 54c spaced around the center C2 (equally spaced 90 degrees apart in this embodiment).

7 and 10, the mounting portion 55 is provided as a raised portion on the outer surface of the horizontal pipe 21. However, the mounting portion 55 may be provided on the pump casing 12 or the installation floor 1, as long as it is a fixed, rigid body. The mounting portion 55 has multiple bolt holes 55a corresponding to the mounting holes 54c, spaced apart around the center C3. Because the center C1 of the take-up portion 54a and the center C2 of the mounting flange 54b are eccentric, changing the attitude (position) of the take-up portion 54a relative to the mounting portion 55 changes the position of the center C1 of the take-up portion 54a relative to the mounting portion 55 and the length of the spring material 53 unwound from the take-up portion 54a. This changes the clockwise load (in FIG. 4) applied to the arm 51 by the spiral spring 52 via the weight 56, i.e., the load in the direction that closes the flap valve 35, thereby adjusting the pressure difference (timing) at which the flap valve 35 switches from a closed state to an open state.

10, when the winding member 54 is attached in a position where the center C1 of the winding portion 54a is located above the center C3 of the attachment portion 55, the unwound length of the spring material 53 is shortest, and the biasing force of the spiral spring 52 on the flap valve 35 is smallest (first attachment state). As shown by the dashed-dotted line in FIG. 10, when the winding member 54 is attached in a position where the center C1 of the winding portion 54a is located to the right of the center C3 of the attachment portion 55, the unwound length of the spring material 53 is longer than in the first attachment state, and the biasing force of the spiral spring 52 on the flap valve 35 is greater than in the first attachment state (second attachment state). As shown by the two-dot chain line in Figure 10, when the winding member 54 is attached in a position where the center C1 of the winding portion 54a is located below the center C3 of the attachment portion 55, the unwound length of the spring material 53 is the longest, and the biasing force of the spiral spring 52 on the flap valve 35 is the greatest (third attachment state). When the spring material 53 is unwound in this third attachment state, the unwound portion becomes the linear portion 53b, and the biasing force becomes constant. In this way, in this embodiment, a constant-load spiral spring 52 is used as the biasing member, but by changing the attachment state, the biasing force on the flap valve 35 can be fine-tuned within the range of the initial deflection.

Referring to Figures 4 and 7, the weight 56 is disk-shaped and is detachably attached to the first portion 51a of the arm 51 in Figure 4. The weight 56 applies a clockwise load to the arm 51, i.e., a load in the direction that closes the flap valve 35. Several types of weights 56 with different weights are provided, and by replacing the weights 56 with weights of different weights, the pressure difference (timing) at which the flap valve 35 switches from a closed state to an open state can be adjusted.

The weight 56 has an insertion hole 56a through which the arm 51 can be inserted, and is held in place by a well-known holding mechanism (not shown) on the arm 51 so that it cannot fall off. By changing the attachment position of the weight 56 relative to the arm 51, i.e., by changing the distance from the rotation axis 37, the load on the flap valve 35 can be adjusted even with the same weight 56. The weight 56 also has a screw hole (connection part) 56b that mechanically connects the spring material 53.

Referring to FIG. 4, the damper 57 has an upper end attached to the second part 51b of the arm 51, which is the side opposite the weight 56, and a lower end attached to the horizontal pipe 21, and damps the vibration and amplitude of the flap valve 35 as it opens and closes. In this embodiment, the damper 57 is a damping member with adjustable damping force. However, the lower end of the damper 57 may be attached to the pump casing 12 or the installation floor 1, as long as it is a fixed rigid body. The damping member may be configured to provide Coulomb damping due to dynamic friction resistance, to provide viscous damping due to viscous resistance, or may be an elastic member. Any configuration can be used as long as it can damp the vibration of the flap valve 35 without interfering with the opening and closing of the flap valve 35.

Figure 11 is a graph showing changes in pump performance of the vertical pump 10 of this embodiment. In Figure 11, the horizontal axis is Q/Qopt, the ratio of flow rate Q to the optimal flow rate Qopt, and the vertical axis is H/Hopt, the ratio of head H to the optimal head Hopt. Depending on the specific speed, in Figure 11, the region where Q/Qopt is less than approximately 70% is the partial flow rate region, the region where Q/Qopt is approximately 120% or more is the excessive flow rate region, and the range between these is the rated operating region. In normal operation, the motor 17 is controlled to be in the rated operating region or the excessive flow rate region, and in managed operation, the motor 17 is controlled to be in the partial flow rate region.

In Figure 11, Qb1 indicates the pump head H when the opening and closing timing of the flap valve 35 is adjusted using only the spiral spring 52. Qb2 indicates the pump head H when the opening and closing timing of the flap valve 35 is adjusted using only the weight 56. Qb3 indicates the pump head H when the opening and closing timing of the flap valve 35 is adjusted using only a general coil spring (not shown). The closing force of all flap valves 35 using the spiral spring 52, weight 56, and coil spring is the same.

Referring to Figure 11, when operating in the excessive flow rate range, the pump head H is lower than when operating in the partial flow rate range, and the pressure P in the discharge elbow 14 shown in Figure 1 is lower than the pressure Pd in the horizontal pipe 21 and the pressure Ps in the suction sump 2. As a result, the flap valve 35 is closed, and no pumped water is returned to the suction sump 2 through the bypass pipe 20. However, because the discharge flow rate Q increases, an air-sucking vortex may occur in the suction sump 2, where the water level has dropped due to drainage. However, in this embodiment, as shown in Figure 1, the vertical pipe 22 of the bypass pipe 20, which is arranged around the lift pipe 13, can suppress the occurrence of an air-sucking vortex. Therefore, the vertical pump 10 of this embodiment is capable of draining water in the excessive flow rate range during normal operation. During normal operation in the rated operating range, the discharge flow rate Q is lower than when operating in the excessive flow rate range, but stable drainage is possible.

When operating in the partial flow rate range, the pump head H is higher than when operating in the excessive flow rate range. Therefore, the pressure P in the discharge elbow 14 shown in FIG. 1 is higher than the pressure Pd in the horizontal pipe 21 and the pressure Ps in the suction sump 2. As a result, when the pressure reaches or exceeds the return head Hb, the flap valve 35 opens, and a portion of the pumped water is returned to the suction sump 2 through the bypass pipe 20. This allows a portion of the pumped water to be discharged near the suction port 13a via the bypass pipe 20, thereby scooping up sludge at the bottom 3 of the suction sump 2 and discharging it with the vertical pump 10. This allows the interior of the suction sump 2 to be cleaned. Furthermore, without return flow through the bypass pipe 20, backflow occurs at the inlet (suction port 13a side) of the impeller 16, potentially causing cavitation and vibration. However, in this embodiment, a portion of the pumped water is returned through the bypass pipe 20, thereby suppressing backflow at the impeller 16. As a result, in the vertical pump 10 of this embodiment, the operation of the impeller 16 from the partial flow rate region to the shutoff point is reduced, expanding the operating range in the small flow rate region.

Referring to Qb3 in Figure 11, it can be seen that when a coil spring is used, the closing force (biasing force) of the coil spring increases in proportion to the opening angle even when the flap valve 35 is open, making it difficult to ensure a sufficient bypass flow rate. Referring to Qb1 in Figure 11, it can be seen that when a constant-load spiral spring 52 is used, the closing force (biasing force) remains constant regardless of the opening angle after the flap valve 35 opens, making it easy to ensure a sufficient bypass flow rate. It can also be seen that by changing to a spiral spring 52 or coil spring with a different biasing force and changing to a weight 56 with a different weight, it is possible to adjust the bypass start head Hb, and thereby adjust the bypass head Hb and bypass discharge volume Qb.

When inspecting the interior of the pump casing 12 of the vertical pump 10 of this embodiment, the motor 17 is stopped to halt operation. Then, as shown in FIG. 3, the eyebolt 29 is operated to open the door 26, and the arm 51 is operated to manually open the flap valve 35. In this state, a measuring device such as an endoscope is inserted into the pump casing 12 through the opening 25a, using the open flap valve 35 as a support. If the measuring device is unstable during insertion, a support base 60 with a U-shaped cross section can be placed on the door 26 as a special guiding tool (see FIG. 3). This allows for accurate inspection of the interior of the pump casing 12. Furthermore, by fixing the arm 51 with a rod or chain (not shown) and holding the flap valve 35 in the open position, the ease of inspection using the measuring device can be improved.

The vertical pump 10 configured in this manner has the following features:

A flap valve 35 is attached to the bypass pipe 20, which can rotate from a closed state to an open state when the pressure P inside the pump casing 12 becomes higher than the pressure Pd inside the bypass pipe 20. The pressure Pd inside the bypass pipe 20 becomes higher than the pressure P inside the pump casing 12 during normal operation for the purpose of drainage, and becomes lower than the pressure P inside the pump casing 12 during maintenance operation that is not intended for drainage. Therefore, the flap valve 35 is closed during normal operation and open during maintenance operation. Because the flap valve 35 does not require a drive source to switch between the open and closed states, the running costs of the pump equipment can be reduced.

An adjustment mechanism 50 is attached to the rotating shaft 37 of the flap valve 35 to adjust the force that keeps the flap valve 35 closed, allowing the pressure difference (timing) at which the flap valve 35 opens and closes to be adjusted. This allows the flap valve 35 to be reliably and automatically opened and closed according to the operating state, switching to a closed state during normal operation and an open state during maintenance operation.

An arm 51 is attached to the outer end of the rotating shaft 37 of the flap valve 35 that protrudes from the bypass pipe 20. Therefore, the flap valve 35 can be opened and closed manually by operating the arm 51. This allows a measuring instrument to be inserted through the horizontal pipe 21 to inspect the inside of the pump casing 12.

The adjustment mechanism 50 includes a spiral spring 52 that biases the flap valve 35 to the closed position via the arm 51 and the rotary shaft 37. Therefore, by using a spiral spring 52 with an appropriate biasing force, the timing at which the flap valve 35 opens and closes can be reliably adjusted. This ensures that the flap valve 35 can be automatically opened and closed reliably according to the operating conditions.

Because a constant-load spiral spring 52 is used, when a predetermined pressure difference is reached between the pump casing 12 and the bypass pipe 20 and the closed flap valve 35 switches to an open state, the opening angle of the flap valve 35, which is the valve opening degree, is maintained constant. As a result, the amount of pumped water flowing out of the pump casing 12 can be maintained and secured constant during maintenance operation.

A mounting portion 55 is provided on either the bypass pipe 20, the pump casing 12, or the installation floor 1 to attach the winding member 54 so that the unwinding length of the spring material 53 from the winding member 54 varies. The constant-load spiral spring 52 has an initial deflection, and the biasing force (load) gradually increases within the range of this initial deflection. Therefore, by changing the position of the winding member 54 attached to the mounting portion 55, the pressure difference (timing) at which the flap valve 35 rotates can be adjusted. This ensures that the flap valve 35 can be automatically opened and closed according to the operating conditions.

The adjustment mechanism 50 includes a weight 56 that can be detachably attached to the arm 51. Therefore, by using a weight 56 of an appropriate weight, the timing at which the flap valve 35 opens and closes can be reliably adjusted. This ensures that the flap valve 35 can be automatically opened and closed reliably according to the operating conditions.

A damper 57 is attached to the arm 51 to dampen the vibration of the flap valve 35. This prevents chattering that occurs when the flap valve 35 opens and closes.

The bypass pipe 20 comprises a horizontal pipe 21 connected to the pump casing 12 and a vertical pipe 22 for discharging the outflowing pumped water into the suction tank 2. During normal operation, the flap valve 35 is switched to a closed state, preventing the bypass pipe 20 from affecting the drainage water passing through the pump casing 12 and allowing the water in the suction tank 2 to be efficiently discharged. Furthermore, the vertical pipe 22 located inside the suction tank 2 prevents the occurrence of air-sucking vortices that can occur in the suction tank 2 during normal operation. During maintenance operation, the flap valve 35 is switched to an open state, allowing a portion of the pumped water to be returned to the suction tank 2 through the bypass pipe 20, allowing the area around the pump casing 12 to be cleaned (maintenanced).

The end of the horizontal pipe 21 is closed by a door 26 that can be opened and closed. Therefore, by opening the door 26 and setting the flap valve 35 to an open position, a measuring device such as an endoscope can be inserted to inspect the inside of the pump casing 12. Because pumping pressure is not applied to the door 26 during normal operation, the durability required for the door 26's sealing structure can be reduced.

At least a portion of the door 26 is translucent, so the open/closed state of the flap valve 35 can be easily confirmed through the door 26 during both normal operation and maintenance operation. Furthermore, during maintenance operation, the return state of some of the pumped water can be easily confirmed through the door 26.

The door 26 is provided with a holder 28 that holds it in an open position so that it extends along the axis of the horizontal pipe 21. This allows the door 26 to be used as a support base when inserting a measuring instrument from the horizontal pipe 21 of the bypass pipe 20 into the pump casing 12, improving workability during inspection.

Note that the present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

For example, a tension spring may be used as the biasing member instead of the spiral spring 52. Also, the biasing member may be directly connected to the first portion 51a of the arm 51.

Multiple mounting portions 55 may be provided at intervals in the vertical direction on the horizontal pipe 21, allowing the length of spring material 53 unwound from the winding member 54 to vary without changing the position of the winding member 54 of the spiral spring 52. In other words, the mounting portions 55 can be changed as needed, as long as they are configured to change the length of spring material 53 unwound from the winding member 54.

A pipe for discharging a portion of the pumped water to a location other than the suction tank 2 may be connected to the bypass pipe 20. In this case, the bypass pipe 20 may be composed of only the horizontal pipe 21, and may not include the vertical pipe 22 or the annular pipe 23. The vertical pipe 22 may be open at the top of the suction tank 2, without extending to near the bottom end of the pump casing 12.

The pump may be of any type, provided it has a cylindrical pump casing, an impeller for discharging water, and is capable of switching between normal operation and controlled operation.

1 Installation floor 2 Suction tank 3 Bottom 5 Discharge pipe 6 Gate valve 10 Vertical pump (pump)
12 Pump casing 13 Lifting pipe 13a Suction port 14 Discharge elbow 15 Rotating shaft 16 Impeller 17 Motor 18 Control unit 20 Bypass pipe 21 Horizontal pipe (first pipe)
21a Inner end 21b Outer end 21c Connection portion 21d Cylindrical portion 21e Bearing portion 21f Insertion portion 22 Vertical pipe (second pipe)
22a Upper end (first end)
22b Lower end (second end)
23 Circular piping (third piping)
23a Nozzle 24 Lid 25 Mounting plate 25a Opening 26 Door 27 Hinge 28 Holding portion 29 Eyebolt 30 Bracket 35 Flap valve 36 Valve body 37 Rotating shaft 38 Movable valve seat 39 Fixed valve seat 40 Seal member 41 Ball bearing 42 Bearing member 50 Adjustment mechanism 51 Arm 51a First portion 51b Second portion 52 Power spring (biasing member)
53 Spring material 53a Tip portion 53b Linear portion 53c Connection hole 54 Winding member 54a Winding portion 54b Mounting flange 54c Mounting hole 55 Mounting portion 55a Bolt hole 56 Weight 56a Insertion hole 56b Screw hole 57 Damper (damping member)
60 Support stand

Claims (6)

a cylindrical pump casing partially disposed within the suction tank;
an impeller rotatably disposed within the pump casing for discharging water from the suction tank;
a bypass pipe arranged outside the pump casing, branched and connected to the pump casing downstream of the impeller, for allowing a portion of the pumped water discharged through the pump casing to flow out of the pump casing;
a flap valve having a rotating shaft rotatably supported on the bypass pipe, and which is rotatable in a direction away from the pump casing from a closed state in which the outflow of the pumped water is blocked to an open state in which the outflow of the pumped water is allowed when the pressure in the pump casing becomes higher than the pressure in the bypass pipe;
an adjustment mechanism attached to the rotary shaft for adjusting the force that maintains the flap valve in the closed state ,
At least one end of the rotating shaft penetrates the bypass pipe and protrudes to the outside,
an arm is provided at the one end of the rotation shaft,
The adjustment mechanism includes a biasing member formed by a constant-load spiral spring connected to the arm and biasing the flap valve to a closed position via the arm and the rotating shaft . the power spring includes a strip-shaped spring material connected to the arm and a winding member that winds up the spring material so that the spring material can be unwound,
any one of the bypass pipe, the pump casing, and an installation floor to which the pump casing is fixed includes an attachment portion for attaching the winding member ;
The mounting portion is changeable to a plurality of mounting states having different unwinding lengths of the spring material from the winding member .
2. The pump of claim 1 . The pump of claim 1 or 2 , wherein the adjustment mechanism comprises a weight removably attached to the arm. 3. The pump according to claim 1 , wherein a damping member is attached to the arm to damp vibration of the flap valve. The bypass pipe is
a first pipe extending in a direction intersecting the pump casing;
a second pipe having a first end branched off from the first pipe and a second end disposed within the suction tank, for discharging the outflowing pumped water into the suction tank,
The pump according to claim 1 or 2 , wherein the flap valve is disposed in the first pipe between the first end of the second pipe and the pump casing. The pump according to claim 5 , wherein an end of the first pipe opposite to the pump casing is closed by a door having at least a portion that is translucent and that can be opened and closed.