JPH06330883A - Shaft power reducer of pump - Google Patents

Abstract

PURPOSE:To abate the extent of shaft power in time of starting by reducing this shaft power in taking such a step as bypassing a fluid to the side of suction port from the discharge port in use of fluid pressure in a pump, whereas this shaft power becomes higher than the rated value shaft power at the time of pump starting. CONSTITUTION:When shaft power grows larger at the shutoff of a pump, two pressure detecting pipes 6A and 6B detects a pressure differential by means of a swirling flow to be produced at the side of a suction pipe. This pressure differential rotates a valve stem of a rotary switch 7, opening or closing the flow passage. A fluid flowing into a cylinder 11 is opened or closed by operation of this rotary switch 7 and thereby a piston is operated, opening a bypass valve, and a bypass pipe 13 is interconnected to it, and then the fluid in the pump is made to flow into a suction pipe 5 from a discharge pipe 4, whereby shaft power is thus reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump shaft power reduction device for reducing the dead shaft power when starting a pump.

[0002]

2. Description of the Related Art Conventionally, in a mixed flow, axial flow pump having a large specific gravity, as shown in FIG. 16, the axial power Psh during the shutoff operation of the pump (flow rate Q = 0) becomes larger than the rated point power Pn. Is normal. Further, when the pump is started, since the discharge valve is normally started from the closed state in which the discharge valve is closed, it is necessary to have a driving machine sufficient to cover the shaft power Psh at the cut-off point rather than the shaft power Pn at the rated point. Further, as shown in FIG. 17, the main part of the pump is composed of an impeller 1, guide vanes 2 and a bell mouth 3. As described above, the high specific speed pump requires a motor having a higher output than the dead shaft power because the dead shaft power is higher than the specification shaft power. This is because the start of the pump is normally performed in the deadline operation, but a motor with a high output has a high cost, so a pump with a small deadline shaft power is desired. Conventionally, as a countermeasure against this, a suction ring 4 as shown in FIG. 17 is provided immediately before the inlet. This is because the suction ring 4 provides a tightening portion in front of the impeller inlet, and the backflow region 4 generated at the blade inlet is
It is intended to suppress the shutoff shaft power by the flow indicated by 41 (illustrated by the solid line) while suppressing 0 (illustrated by the dotted line).

It is also well known that if the entrance of the impeller is always swung in the same direction as the direction of rotation of the impeller, the work of the impeller is somewhat reduced, and the axial power at the deadline is reduced.

[0004]

As described above, conventionally, at the time of starting the pump, a power larger than the shaft power at the rated point is required. Therefore, the performance at the rated operation is sacrificed, and FIG. In order to avoid the region of P> Pn as shown in (1), it is necessary to provide a complicated control mechanism.

Further, in the conventional shut-off shaft power reduction mechanism shown in FIG. 17, when the flow rate increases and becomes close to the specification point, the suction ring 4 in this throttle portion prevents running water from smoothly flowing into the impeller. It has the drawback of reduced efficiency and suction performance.

An object of the present invention is to reduce the shutoff shaft power by utilizing the pressure difference between the suction side and the discharge side without providing an obstacle in the flowing water portion as much as possible.

[0007]

In order to solve the above problems, the present invention detects the pressure of a fluid by providing a bypass pipe between the suction port and the discharge port of a pump for bypassing the fluid when the pressure rises. Control the opening and closing of the valve to reduce the shaft power by bypassing the fluid from the discharge port to the suction port when the shaft power becomes larger than the rated value as when starting the pump. This is to reduce the axial power by injecting the bypassed fluid so as to suppress the backflow generated on the suction port side at the deadline.

That is, according to the first aspect of the invention, the shaft power is reduced by connecting the discharge port and the suction port of the pump with a bypass pipe to allow the fluid to flow from the discharge port side to the suction port side to reduce the shaft power of the pump. A device, comprising: a bypass valve for opening and closing the bypass pipe; a pair of pressure detection pipes arranged so that detection holes around the suction port of the pump are circumferentially forward and backward. The rotary switch is driven by the differential pressure detected by the pair of pressure detection tubes, and the flow path is opened / closed by the rotation of the valve shaft, and the opening / closing operation of the rotary switch causes the pressure at the discharge port of the pump to become higher than a predetermined pressure. A shaft power reduction device for a pump, comprising: a bypass valve opening / closing mechanism for opening the bypass valve so that the bypass pipe can communicate with each other when the shaft power increases.

According to the second aspect of the invention, the pump power is reduced by connecting the discharge port and the suction port of the pump with a bypass pipe to allow the fluid to flow from the discharge port side to the suction port side and reduce the pump shaft power. In the device, one end is opened to the outlet wall surface of the pump and the other end is provided with a spring to seal the casing, and the casing communicates with the bypass pipe, and one end of the bypass pipe is in contact with the open end of the casing. The flow passage is closed, the other end is attached to the spring and slidable inside the casing, and when the pressure at the discharge port exceeds a predetermined pressure, it slides against the spring force and the The present invention provides a pump shaft power reduction device, characterized in that the pump shaft power reduction device is provided with an oscillating portion that allows the passages to communicate with each other.

Further, according to the invention of claim 3, a shaft power reducing device for reducing the shaft power of the pump by connecting the discharge port and the suction port of the pump with a bypass pipe to allow the fluid to flow from the discharge port side to the suction port side. And a pressure sensing valve that detects the pressure at the discharge port of the pump and connects the flow path of the bypass pipe when the pressure at the discharge port exceeds a predetermined pressure, and the impeller inlet side of the pump suction port. In order to suppress the swirling flow generated at the inlet of the same impeller by guiding the fluid from the bypass pipe which is provided in the periphery and is in communication with the impeller rotation direction from the peripheral portion and which is communicated by the operation of the pressure sensing valve. The present invention provides a shaft power reducing device for a pump, comprising:

[0011]

The present invention is the above-mentioned means. In the invention of claim 1, when the axial power of the pump increases, a swirl flow is generated on the suction port side, and the pair of pressure detection pipes generate a swirl flow. On the other hand, since the detection holes are arranged in opposite directions, the differential pressure is detected. This differential pressure rotates the valve shaft of the rotary switch to operate the bypass valve opening / closing mechanism, open the bypass valve provided in the middle of the bypass pipe, and connect the discharge port and suction port of the pump with the bypass pipe. , Will reduce the axial power.

Further, in the invention of claim 2, when the axial power of the pump increases, the swinging portion in the casing provided in the bypass pipe is pushed by the pressure in the discharge port of the pump against the spring force. By sliding, the bypass pipe is brought into communication between the discharge port and the suction port of the pump to reduce the shaft power.

According to the third aspect of the present invention, when the axial power of the pump increases, the pressure sensing valve detects the pressure at the discharge port of the pump and opens the bypass pipe for communication so that the fluid is sucked from the discharge port side. It is directed to the side and jetted from multiple nozzles. The nozzle injects a fluid to reduce the shaft power, and at the same time, prevents the swirling flow generated as the shaft power rises to reduce the shaft power.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings. FIG. 1 is an overall conceptual diagram of a shaft power reduction device according to a first embodiment of the present invention, and FIG. 2 is a detailed configuration diagram. 3 (a) and 3 (b) are explanatory views showing the fluid flow relationship in the first embodiment, FIG. 4 is a system diagram showing the operation in the first embodiment, and FIG. 5 shows the structure of the rotary switch. 6A and 6B are sectional views taken along the line AA in FIG.
It shows the state due to the operation of the switch.

In FIG. 1, the overall structure is such that the pressure detecting pipes 6A and 6B, the rotary switch 7, the bearing portion 9, the cylinder 11, the bypass pipe 13 are provided between the suction pipe 5 and the discharge pipe 4 of the pump.
It consists of the main parts of. In the detailed view of FIG. 2, the pump main body is composed of an impeller 1, guide vanes 2, a main shaft 3, a discharge pipe 4, and a suction pipe 5, and the flow flows from the suction pipe 5 to the discharge pipe 4. In the vicinity of the rated point, the flow rates of the suction pipe 5 and the discharge pipe 4 are both Q, but when the self-control device in the embodiment operates, Qmin flows through the bypass pipes 13 and 18, so that the flow amount of the discharge pipe 4 is It becomes Q-Qmin. The bypass pipes 13 and 18 are opened and closed by the bypass valve 10. Bypass valve 10
The opening mechanism includes a cylinder 11, a piston 12, connecting tubes 14a, 14b, 14c, and a pressure balancing circuit 17
And the bypass valve 1 in conjunction with the rotary switch 7.
It opens and closes 0. Reference numeral 7 denotes the above-mentioned rotary switch, which uses the flap valve 8 to connect the bearing portion 9 to the pressure detection tubes 6A, 6
It is a mechanism that operates at the pressure detected at B. Pressure detection tube 6
A and 6B are arranged facing each other around the inlet of the impeller 1 of the suction pipe 5. Reference numerals 14a and 15 are communication pipes that communicate from the cylinder 11 to the bearing 9 and from the bearing 9 to the bypass pipe 18, respectively.

Next, the operation of the shaft power reducing apparatus in the first embodiment having such a configuration will be described. First, the method of sensing the region where P> Pn is as shown in FIGS.
In the state of Pn, a reverse flow is generated in the impeller 1, and a swirling flow 16 is generated in the suction pipe 5 in the circumferential direction. As shown in (a), the suction pipe 5 has pressure detection pipes 6A and 6A whose pressure detection holes are opposite to each other in the flow direction (forward direction, reverse direction).
If B is provided, the pressure detected by this is (Ps) A = (Ps) B when the inlet backflow does not occur, but when the backflow swirl flow 16 is generated, In the example (P
Since s) A> (Ps) B, it can be sensed that the state has changed. Although the pressure detection tubes 6A and 6B have been described as a pair of examples, a plurality of pairs of pressure detection tubes may be applied instead of one pair to detect the differential pressure of the reverse swirl flow to improve the detection accuracy. It is a thing. Further, the sliding portions of the cylinder 11 and the piston 12 and the bearing portions 9a and 9b of the flap valve 8 are limited within a range that does not impair the operation, but since there is no particular seal, there is some leakage (Pd). Since there is a difference between A and (Pd) B, a balancing circuit 17 is provided if necessary.

Next, the control of the bypass valve opening / closing mechanism will be described. FIG. 4 shows an opening / closing mechanism of the bypass valve 10. The rotary switch 7 is provided with a flap valve 8 that opens and closes in one direction by a slight pressure difference, and its bearing portion 9 is as shown in FIG. When the flap valve 8 is opened to the bearing 9a
The flow passage 9c is connected to the flow passage 9d of the bearing 9b. The pressure (Ps) A from the suction pipe 5 is applied to both chambers partitioned by the flap valve 8 of the rotary switch 7.
, (Ps) B are derived. In this case, pressure (Ps) B, which is low in pressure, is connected to the opening side of the flap valve 8. A high-pressure pump discharge pressure (Pd) B is guided to the bearing portion 9a through a cylinder 11 that opens and closes a bypass valve 10 by a pipe 14a. The flow path of the bearing portion 9b is connected to the suction pipe 5. On the other hand, the bypass valve 10 is normally closed due to the difference between the pump discharge pressure Pd and the suction pressure Ps. Closing force F
Is F≈f ₁ (Pd −Ps), where f ₁ is the valve area.
Further, the discharge pressure Pd is above and below the piston 12 in the cylinder 11.
In this state, it is not related to the opening and closing of the valve. This state is shown in FIG.

The opening and closing of the valve 10 will be specifically described below. When an inlet backflow occurs, (Ps) A>
(Ps) B. At this time, the flap valve 8 is opened, the flow paths of the bearing portion 9a and the bearing portion 9b are short-circuited, and the pressure (Pd) B in the lower portion of the cylinder flows through the connecting pipe 15 to the suction pipe 5. This state is shown in FIG. At this time, (Pd) A
> (Pd) B, the bypass valve 10 opens and the discharge side communicates with the suction side, and the bypass circuit functions. Therefore, P> P
The state of n is avoided and the power at the time of starting the pump is reduced.

Next, a second embodiment of the present invention will be described with reference to FIGS.
The description will be made using 0. FIG. 7 is a conceptual diagram showing an overall configuration to which the shaft power reduction device is applied, FIG. 8 is a diagram illustrating the configuration of FIG. 7 in detail, FIG. 9 is a sectional view taken along line BB in FIG. 8, and FIG. 10 is a shaft power reduction. It is a graph which shows an effect.

In FIG. 7, 20 is a pump, 24 is a discharge valve, and this apparatus is composed of a bypass pipe 25 and a bypass valve 26. In FIG. 8, 21 is an impeller, 2
2 is a guide vane, 23 is a bell mouth, 25 is a bypass pipe,
Reference numeral 26 is a bypass valve, 27 is an oscillating portion of a component of the bypass valve, 27a is a hole provided in the oscillating portion 27, 28 is a spring also shown by an elastic material of the component, and 29 is also a casing. .

Next, the operation of the second embodiment having such a structure will be described. First, when the pump is started, the discharge valve 24 on the downstream side of the pump is fully closed.
Up to 4, there is no place for water to flow out, and the pressure in the pipeline during this period increases as the rotation starts and rotation increases. On the other hand, the oscillating portion 27 incorporated in the bypass valve 26 provided in the middle of the bypass pipe 25 has no spring in the head portion in contact with the flowing water portion of the oscillating portion 27 when the pump is stopped and there is no spring. The swinging portion 27 is pushed by being balanced by the force of 28 so that its head portion is flush with the flowing water portion of the pump conduit. However, when the pump is activated and pressure is applied to the head portion of the oscillating portion 27, this water pressure overcomes the force of the spring 28 and the oscillating portion 27 moves in the casing 29.

FIG. 8 shows this moved state, and in this state, the hole 27a provided in the swinging portion 27 communicates with the bypass pipe 25 as shown in the section BB in FIG. Water with a high drop pressure flows from the discharge side of the pump through the bypass pipe 25 to the low pressure section upstream of the pump.

Further, when the discharge valve 24 shown in the general view of FIG. 7 is close to the open specification point, the water pressure acting on the head of the oscillating portion 27 decreases, so that the oscillating portion 27 again has the spring 28.
Force moves to the discharge pipe line of the pump, the bypass pipe and the hole 27a of the oscillating portion are displaced, the flow passage of the bypass pipe 25 is closed, and the running water stops.

FIG. 10 shows the range of shaft power reduction. In the vertical axis, (a) is the lift and (b) is the shaft power. H is the pump head, Q is the pumped water amount, P is the shaft power, and Pn, Hn, and Qn are the shaft power, pump head, and pumped water amount at the specification point n, respectively. In the figure (b), when there is no such shaft power reducing device, the deadline shaft power is point A, but when the shaft power reducing device is applied and the effect is produced, it becomes point B and the range of shaft power reduction is It is a hatched portion in the figure. That is, as seen from the lift curve in FIG. 8A, the pressure acting on the head of the oscillating portion 27 shown in FIG. 8 exceeds the force of the spring 28 in the deadline, that is, in the pressure range from point C to point D. The flowing water flows through the bypass pipe 25. That is, it indicates that the bypass pipe 25 flows up to the flow rate corresponding to the point D.

Further, when the original discharge valve 24 shown in FIG. 7 is opened and pumping is started, the pressure from the point D to the specification point drops, and conversely to the above, the bypass valve 26 is closed and normal pump operation is performed. Becomes

As described above, in the second embodiment, the bypass pipe 25 and the bypass valve 26 provided on the way are automatically opened and closed according to the water pressure, so that the axial power of the pump can be reduced and the motor The capacity of can also be reduced.

Next, a third embodiment of the present invention will be described with reference to FIGS.
5 will be described. FIG. 11 is a conceptual diagram of the entire pump to which the shaft power reducing device is applied, FIG. 12 is a vertical sectional view showing the detailed configuration thereof, FIG. 13 is a sectional view taken along line CC of FIG. 12, and FIG. FIG. 15 is a graph showing the relationship between the pump operation mode and the pressure sensing valve.

In FIG. 11, in the third embodiment, 30 is a pump main body, 33 is a bell mouth, 34 is a discharge valve, 35 is a bypass pipe attached to the pump main body, and 35a is an annular shape communicating with a bypass pipe 36. Pressure pipe, 36 is bypass pipe 35
A pressure sensing valve provided in the middle of the
The jet nozzle 38 communicating with the pump main body 6 is composed of a pilot pipe connected to the pressure sensing valve 36.

Next, the operation of this structure will be described.
When the pump is started in the shut-off state, water is boosted by the impeller 31 but does not flow, so that a large backflow area is formed at the inlet of the impeller 31. When the rotation speed approaches the rated speed, the discharge pressure further rises, so that the pressure sensing valve 2 operates and is fully opened. A part of the water in the discharge pipe passes through the bypass pipe 35, further passes through the annular pressure pipe 35a provided in the bell mouth 33 and the jet nozzle 37, and is jetted just before the inlet of the impeller 31. As shown in FIG. 13, jet nozzles 37 are provided at four locations in the circumferential direction of the bell mouth 33. The jet nozzles 37 are angled so as to eject jets in the same direction as the pump rotation direction R. There is. The number of nozzles is not 4 but may be 4 or more if large backflow is to be prevented depending on the type of pump. That is, the backward flow region generated at the impeller inlet portion during the pump shutoff operation is jetted by the jet nozzle 37 to give a pre-turn 39,
This has the effect of reducing the deadline shaft power.

When the pump discharge amount increases, the head is lowered, so that the pressure sensing valve 36 is actuated to be fully closed and the ejection is stopped. Therefore, near the pump specifications, the original performance is exhibited without deterioration of pump efficiency and suction performance.

FIG. 14 shows the power reduction effect in this case. In the figure, H is the head, P is the shaft output, Q is the pumping amount,
Hn, Pn, and Qn are the head, the shaft output, and the pumping volume at the specification point n, respectively. The solid line shows the shaft output, and the one-dot chain line shows the head. When the shaft power reduction device is not applied, the dead shaft power is at point A, but when the jet action of the jet nozzle 37 occurs, it becomes point B and the flow rate increases and the pressure sensing valve operates when the discharge pressure drops to point C. It becomes fully closed, the jet flow stops, and normal pump operation starts. Therefore, the shaft power reducing portion according to the present invention is a hatched portion.

FIG. 15 shows an example of the pump operation mode, which shows the relationship between the time from pump startup to the setting of the specification point and the lift, and also shows the correlation between the opening of the main valve and the pressure sensing valve. It takes about 10 seconds from the start of the pump to the rated rotation, during which the pressure sensing valve is fully closed to fully open. Since the discharge pressure drops while the discharge valve is fully closed to fully open, the pressure detection valve closes and normal operation starts when the pressure falls below the detection valve set pressure.

As described above, in the third embodiment, the bypass pipe 35 and the pressure sensing valve 36 provided in the middle of the bypass pipe 35 are provided, and the pressure sensing valve 36 detects the water pressure to form an annular shape near the suction port. Since the backflow is suppressed by ejecting a jet from the provided jet nozzle 37 in the rotation direction of the pump, the shaft power is reduced, and the pump can be started by a motor capable of covering the point power of the pump specification. ,
The motor output is less than that of the conventional one, and the cost can be reduced.

[0034]

As described above in detail, in the present invention, the fluid pressure is utilized by the bypass pipe provided between the discharge port and the suction port during the shutoff operation of the pump or the partial load operation. The pressure is adjusted, and the fluid is bypassed from the discharge side to the suction side and the reverse swirl flow is prevented by injecting with a nozzle to reduce the axial power of the pump, which can reduce the motor capacity. Therefore, the cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an overall configuration of a shaft power reduction device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing the details of FIG. 1 together with a sectional view of a pump in the first embodiment of the present invention.

FIG. 3A is a plan view and FIG. 3B is a side view illustrating and explaining the flow of fluid in the first embodiment.

FIG. 4 is a system diagram illustrating the operation of the first embodiment.

FIG. 5 is a sectional view showing a structure of a rotary switch applied to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, where (a) shows a state where the switch is open and (b) shows a state where the switch is closed.

FIG. 7 is a conceptual diagram showing an overall configuration of a shaft power reduction device according to a second embodiment of the present invention.

8 is a configuration diagram showing the details of FIG. 7 together with a sectional view of a pump in a second embodiment of the present invention.

9 is a sectional view taken along line BB in FIG.

FIG. 10 is a graph showing a shaft power reduction effect in the second embodiment of the present invention, in which (a) shows a lift and (b) shows a shaft power relationship.

FIG. 11 is a conceptual diagram showing an overall configuration of a shaft power reduction device according to a third embodiment of the present invention.

FIG. 12 is a configuration diagram showing the details of FIG. 11 together with a cross-sectional view of a pump in a third embodiment of the present invention.

13 is a cross-sectional view taken along the line CC of FIG.

FIG. 14 is a graph showing the shaft power reduction effect according to the third embodiment of the present invention.

FIG. 15 is a graph showing a relationship between a pump operation mode and a pressure sensing valve according to a third embodiment of the present invention.

FIG. 16 is a general characteristic diagram showing a relationship between general shaft power of a pump and a flow rate.

FIG. 17 is a vertical cross-sectional view of a conventional pump for reducing the axial power of the pump.

[Explanation of symbols]

 6A Pressure detection pipe 6B Pressure detection pipe 7 Rotary switch 8 Flap valve 9 Bearing part 11 Cylinder 12 Piston 13 Bypass pipe 25 Bypass pipe 26 Bypass valve 27 Swing part 28 Spring 29 Casing 35 Bypass pipe 35a Pressure pipe 36 Pressure sensing valve 37 Jet nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Oya 2-1-1, Niihama, Arai-cho, Takasago-shi, Hyogo Chugai Technos Co., Ltd.

Claims (3)

[Claims] 1. A shaft power reduction device for connecting a discharge port and a suction port of a pump with a bypass pipe to allow a fluid to flow from the discharge port side to the suction port side and reduce the shaft power of the pump. A bypass valve for opening and closing the pump, a pair of pressure detection tubes arranged so that the detection holes around the suction port of the pump are in the forward and reverse directions in the circumferential direction, and the detection of the pair of pressure detection tubes is performed. A rotary switch which is driven by a differential pressure and whose flow path is opened / closed by the rotation of a valve shaft, and the bypass when the pressure at the discharge port of the pump becomes higher than a predetermined pressure and the shaft power becomes large by the opening / closing operation of the rotary switch. A shaft power reduction device for a pump, comprising: a bypass valve opening / closing mechanism that opens the bypass valve so that the pipes can communicate with each other. 2. A shaft power reduction device for connecting a discharge port and a suction port of a pump by a bypass pipe to allow fluid to flow from the discharge port side to the suction port side to reduce the shaft power of the pump, wherein one end of the shaft power reduction device is A casing communicating with the bypass pipe is opened to the discharge port wall surface of the pump and is closed at the other end, and one end is in contact with the open end of the casing to close the flow passage of the bypass pipe and the other end is An oscillating portion attached to the spring and slidable in the casing, and sliding when the pressure of the discharge port exceeds a predetermined pressure to slide against the spring force to connect the flow path of the bypass pipe. A shaft power reduction device for a pump, comprising: 3. A shaft power reduction device for reducing the shaft power of a pump by connecting a discharge port and a suction port of a pump with a bypass pipe to flow a fluid from the discharge port side to the suction port side. A pressure sensing valve that detects the pressure at the discharge port and connects the flow path of the bypass pipe when the pressure at the discharge port exceeds a predetermined pressure, and a pressure sensing valve that is provided around the impeller inlet side of the pump suction port. A plurality of nozzles for guiding a fluid from the bypass pipe, which is communicated by the operation of the pressure sensing valve, toward the rotational direction of the impeller from the portion to jet the fluid and suppress a swirling flow generated at the inlet of the impeller. A shaft power reduction device for a pump characterized by the following.