JP2007040155A - Self priming pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self priming pump capable of shortening self priming time further. <P>SOLUTION: The self priming pump 2 is provided with a casing 14, a motor 15 and an impeller16 driven and rotated by the motor 15. A centrifugal impeller 16 includes a main plate 31 including a first surface 35 and a second surface 36, and a plurality of blades 32a, 32b attached on the first surface 35. The casing 14 includes a suction port 11, a delivery port 12, a suction chamber leading fluid from the suction port 11 to suction part 16a of the centrifugal impeller 16, and a delivery chamber 2 leading fluid from a delivery part 16b of the centrifugal impeller 16 to the delivery port 12. The casing 14 includes a retention part 23 retaining pressurized water having delivery pressure applied. Holes 38a, 38b penetrating from the first surface 35 to the second surface 36 are opened on the main plate 31 of the centrifugal impeller 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a self-priming pump in which a self-priming operation is performed at startup.

  The self-priming pump performs a pumping operation which is a normal operation and a self-priming operation for shifting from the start to the pumping operation. The self-priming pump includes a casing having a suction port and a discharge port, a motor, and a centrifugal impeller that is rotationally driven by the motor. A pumping pipe is connected to the suction port. The casing has a suction chamber that communicates with the suction port and a discharge chamber that communicates with the discharge port. The centrifugal impeller is disposed in the casing so as to separate the suction chamber and the discharge chamber.

  At the start of starting the self-priming pump, the start-up water is injected into a suction chamber from a separately provided tank, and the centrifugal impeller is immersed. In the self-priming operation, the air in the casing is mixed with this water by the rotation of the centrifugal impeller and discharged into the discharge chamber as gas-liquid mixed water. Thereby, a negative pressure is generated in the suction chamber, and the air in the pumped water pipe connected to the suction port is sucked up.

  The self-priming pump further has a communication pipe that connects the suction chamber and the discharge chamber. The gas-liquid mixed water discharged into the discharge chamber is separated into air and water in the discharge chamber. The separated water is returned to the suction chamber through the communication pipe. The water recirculated to the suction chamber is again mixed with the air in the casing by the centrifugal impeller and discharged to the discharge chamber. The self-priming pump repeats this process to raise the water level in the pumping pipe, and when the water level reaches the height of the suction port, the self-priming pump shifts to the pumping operation.

In this self-priming operation, there is provided a self-priming pump capable of quickly separating and removing gas from water and quickly moving to a pumping operation (for example, see Patent Document 1).
JP 2004-183561 A

In the self-priming pump, the water temperature in the casing is likely to rise during the self-priming operation. In particular, in the case of a pump having a small pump casing, the water temperature tends to rise. When the water temperature in the casing rises in this way, separation of air and water does not proceed well due to the saturation vapor pressure, and the self-priming pump may not be able to self-prime. For this reason, it is desirable that the self-priming time from the start of startup to the pumping operation is as short as possible.
An object of the present invention is to obtain a self-priming pump that can shorten the self-priming time.

In order to achieve the above object, a self-priming pump according to one aspect of the present invention includes:
A casing, a motor, and a centrifugal impeller that is rotationally driven by the motor are provided. The centrifugal impeller includes a main plate having a first surface and a second surface, and a plurality of blades attached to the first surface. The casing includes a suction port, a discharge port, a suction chamber that guides fluid from the suction port to a suction portion of the centrifugal impeller, and a discharge chamber that guides fluid from the discharge portion of the centrifugal impeller to the discharge port. The casing includes a retention portion that retains pressure water to which discharge pressure is applied between the second surface of the centrifugal impeller. A hole penetrating from the first surface to the second surface opens in the main plate of the centrifugal impeller.

  According to this configuration, the self-priming performance is increased by introducing the pressure water, and the self-priming time can be shortened.

  Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 discloses a self-priming pump unit 1 according to an embodiment of the present invention. The self-priming pump unit 1 includes a spiral pump 2 as a self-priming pump, a pumping pipe 3, and a discharge pipe 4. The spiral pump 2 has a suction port 11 and a discharge port 12.

  One end 3 a of the pumping pipe 3 is connected to the suction port 11 of the spiral pump 2. The other end 3b of the pumping pipe 3 is submerged in a fluid, for example, water, below the installation surface F on which the spiral pump 2 is installed. One end 4a of the discharge pipe 4 is connected to the discharge port 12 of the centrifugal pump 2, and the other end is connected to a fluid device (not shown) to which fluid is supplied.

  As shown in FIG. 2, the spiral pump 2 includes a casing 14, a motor 15, a centrifugal impeller 16 (hereinafter referred to as impeller 16), and an installation base 17. The casing 14 and the motor 15 are placed on the installation table 17. The motor 15 includes a motor shaft 15a. The casing 14 includes a casing body 18 and a casing cover 19.

  The casing body 18 includes an upper wall 18a, a front wall 18b, a rear wall 18c, a side wall 18d, and an inner wall 18e. A suction port 11 is opened at the upper end of the front wall 18b. A discharge port 12 is opened in the upper wall 18a. The rear wall 18 c has an opening 18 f that opens to the outside of the casing body 18. The substantially front half of the impeller 16 is inserted into the casing body 18 through the opening 18f.

  As shown in FIG. 2, the casing cover 19 has a front wall 19a, a rear wall 19b, and a side wall 19c. The casing cover 19 has a concave portion 19d having a narrow width between the front wall 19a and the rear wall 19b at the central portion of the front wall 19a. A motor 15 is provided behind the casing cover 19. An insertion hole 19e into which the motor shaft 15a of the motor 15 is inserted is opened at the center of the recess 19d and the center of the rear wall 19b. The motor shaft 15a is inserted into the casing 14 through the insertion hole 15e.

  The casing cover 19 is attached to the casing body 18 from behind the casing body 18 so as to cover the opening 18f of the casing body 18, that is, with the impeller 16 interposed between the casing body 18 and the casing body 18. Thereby, the casing 14 is formed in the box shape sealed watertight. By attaching the casing cover 19 to the casing body 18, the casing 14 has a suction chamber 21, a discharge chamber 22, an impeller rear chamber 23 as a staying portion, and a communication portion 24.

  As shown in FIG. 2, the suction chamber 21 is formed by being surrounded by the upper wall 18a, the front wall 18b, and the inner wall 18e of the casing body 18, and has a flow path extending vertically. The upper part of the suction chamber 21 communicates with the suction port 11. A check valve 26 is provided between the suction chamber 21 and the suction port 11. Thereby, even when the centrifugal pump 2 is stopped, the fluid in the suction chamber 21 does not flow backward to the pumping pipe 3. The lower surface of the suction chamber 21 exposes the front surface of the impeller 16 through the opening of the inner wall 18e. The suction chamber 21 guides the fluid that has passed through the suction port 11 to the front surface of the impeller 16, that is, to the suction side of the impeller 16.

  The impeller 16 is provided between the suction chamber 21 and the discharge chamber 22 at the lower end in the casing 14. In other words, the suction chamber 21 and the discharge chamber 22 are partitioned by the impeller 16. The impeller 16 is rotatably disposed with its axis line horizontal. The impeller 16 includes a main plate 31 and, for example, two blades 32a and 32b.

  The main plate 31 has a front surface 35 as a first surface and a rear surface 36 as a second surface. As shown in FIG. 3, blades 32 a and 32 b are attached to the front surface 35 of the main plate 31. Each of the blades 32a and 32b has a curved shape, and is attached with a 180 ° separation from the center of the main plate 31. That is, the impeller 16 is an open-type impeller, and is a single-suction impeller in which the blades 32 a and 32 b are attached only to one side of the main plate 31.

  As shown in FIG. 3, the main plate 31 of the impeller 16 further includes a plurality of, for example, two return holes 38a and 38b as holes. The return holes 38a and 38b are opened at the center along the circumferential direction between the blades 32a and 32b, for example. The return holes 38 a and 38 b penetrate from the front surface 35 to the rear surface 36 of the main plate 31. The diameter of the return holes 38a and 38b is 3 mm, for example.

  As shown in FIG. 2, the main plate 31 is connected to the motor shaft 15a by, for example, screwing. Thereby, the impeller 16 is rotationally driven by the motor 15. The casing 14 has a seal member that seals between the motor shaft 15 a and the casing cover 19.

  The fluid that has passed through the suction chamber 21 is guided to the front surface 35 of the main plate 31 of the impeller 16, that is, the suction portion 16 a as the suction side of the impeller 16. The fluid sent to the suction portion 16 a of the impeller 16 is pressurized by the rotation of the impeller 16 and discharged from the circumferential side surface of the impeller 16, that is, the discharge portion 16 b as the discharge side of the impeller 16, and the discharge chamber 22. Sent to.

  As shown in FIG. 4, the discharge chamber 22 includes a volute unit 41 and a gas-liquid separation chamber 42. The volute portion 41 is formed so as to be surrounded by the rear wall 18 c, the side wall 18 d, the inner wall 18 e, and the front wall 19 a of the casing cover 19. The volute portion 41 is formed so as to wrap around the entire circumference of the impeller 16 in the circumferential direction. The volute portion 41 is formed in a spiral shape whose cross-sectional area increases in the circumferential direction. The downstream end of the volute part 41 has a nozzle part 43. The nozzle portion 43 communicates with the gas-liquid separation chamber 42.

  The gas-liquid separation chamber 42 is surrounded by the upper wall 18a, front wall 18b, rear wall 18c, side wall 18d, and inner wall 18e of the casing body 18 and is formed above the volute portion 41. The gas-liquid separation chamber 42 communicates with the discharge port 12 from above. That is, the discharge chamber 22 guides the fluid discharged to the discharge portion 16 b of the impeller 16 to the discharge port 12.

  A first flow path 45 is opened through the uppermost portion of the inner wall 18e that partitions between the gas-liquid separation chamber 42 and the volute portion 41 in the vertical direction. The volute part 41 and the gas-liquid separation chamber 42 communicate with each other through the first flow path 45.

  As shown in FIG. 2, a communication portion 24 is provided below the suction chamber 21 and in front of the volute portion 41. As shown in FIG. 4, the communication unit 24 communicates with the gas-liquid separation chamber 42. As shown in FIG. 2, the communication portion 24 is separated from the volute portion 41 by an inner wall 18 e at the lower end portion in the casing 14. A second flow path 46 is opened through the inner wall 18e at the lower end portion in the casing 14 in the horizontal direction. The communication part 24 and the volute part 41 communicate with each other through the second flow path 46.

  On the other hand, the impeller rear chamber 23 is located behind the impeller 16. The impeller rear chamber 23 is formed by being surrounded by the rear surface 36 of the impeller 16 and the recess 19 d of the casing cover 19. That is, the rear surface 36 of the impeller 16 is exposed in the impeller rear chamber 23.

  A gap S is formed between the peripheral end 36 a of the rear surface 36 of the impeller 16 and the front wall 19 a of the casing cover 19. Through this gap S, the impeller rear chamber 23 communicates with the volute portion 41. Here, the gap S is preferably 2 mm or less.

Next, the operation of the self-priming pump unit 1 will be described.
The spiral pump 2 performs a pumping operation that is a normal operation and a self-priming operation from the start to the transition to the pumping operation. As shown in FIG. 5, when the centrifugal pump 2 is started, a fluid, for example, water is injected from a storage tank (not shown) into the suction chamber 21, and the impeller 16 is immersed.

  In this state, the motor 15 is driven. As shown in FIG. 6, when the motor 15 rotates, the water in the suction chamber 21 is sucked into the impeller 16, and this water is discharged to the volute unit 41 by centrifugal force. The water discharged to the volute unit 41 is guided to the nozzle unit 43 along the wall surface of the volute unit 41 and is sent from there to the gas-liquid separation chamber 42. The water sent to the gas-liquid separation chamber 42 is refluxed to the volute unit 41 through the communication unit 24 and the second flow path 46. This refluxed water is used to immerse the impeller 16 again.

  As shown in FIG. 5, the impeller rear chamber 23 retains water injected from a storage tank (not shown) at the time of activation. When the self-priming operation of the spiral pump 2 starts, the water in the impeller rear chamber 23 is in a pressure water state in which the pressure in the volute 41 is propagated through the gap S and the discharge pressure is applied.

  The pressure water is ejected to the front surface 35 side of the impeller 16 through return holes 38 a and 38 b provided in the impeller 16. By the ejection of the pressure water, the water in the suction chamber 21 is bubbled, that is, the air and water in the suction chamber 21 are mixed to obtain gas-liquid mixed water. The gas-liquid mixed water is discharged again to the volute unit 41 by the impeller 16. When the pressure in the impeller rear chamber 23 decreases due to the ejection of the pressure water, the gas-liquid mixed water is replenished from the volute 41 to the impeller rear chamber 23 through the gap S, and the pressure in the impeller rear chamber 23 becomes a predetermined value or more. Kept.

  The gas-liquid mixed water discharged to the volute unit 41 is separated into air and water to some extent by the volute unit 41. As shown in FIGS. 6 and 7, the separated air moves to the gas-liquid separation chamber 42 through the first flow path 45.

  As shown in FIG. 7, the remaining gas-liquid mixed water is guided to the nozzle portion 43 along the wall surface of the volute portion 41 and is sent from there to the gas-liquid separation chamber 42. The remaining air in the state of the gas-liquid mixed water is separated from the water in the gas-liquid separation chamber 42. Air in the gas-liquid separation chamber 42 is discharged to the outside of the centrifugal pump 2 through the discharge port 12.

  As shown in FIGS. 6 and 7, part of the water from which the air has been separated enters the communication part 24 again from the gas-liquid separation chamber 42 and is refluxed to the volute part 41 through the second flow path 46.

  In this way, the air in the suction chamber 21 is sent to the discharge chamber 22, and a negative pressure is generated in the suction chamber 21. By this negative pressure, the air in the pumping pipe 3 is sucked up and the water surface in the pumping pipe 3 is raised. By repeating this process, the water level in the pumping pipe 3 is raised, and if the water level reaches the height of the suction port 11, the spiral pump 2 shifts to the pumping operation.

  According to the spiral pump 2 having such a configuration, the pressure water is ejected to the front surface 35 side of the impeller 16 through the impeller rear chamber 23 and the return holes 38 a and 38 b of the impeller 16. That is, the pressure water is returned to the front surface 35 side of the impeller 16. Here, the front surface 35 side of the impeller 16 includes not only the suction portion 16 a of the impeller 16 but also a space between the front surface 35 and the inner wall 18 e of the casing body 18.

  By ejecting pressure water from the impeller 16, air and water are further agitated on the front surface 35 side of the impeller 16. That is, the mixing of air and water is promoted, and the amount of air taken into the water is increased. By this foaming, the amount of air sucked per rotation of the impeller 16 can be increased, and the efficiency of the self-priming operation of the spiral pump 2 can be increased. Therefore, the self-priming time of the centrifugal pump 2 can be shortened.

  FIG. 8 specifically shows the effect of the return holes 38a and 38b. FIG. 8 is a diagram showing the relationship between the presence / absence of the return holes 38a and 38b of the impeller 16 and the self-priming time. As shown in FIG. 8, when the return holes 38a and 38b are provided, it can be seen that the self-priming time of the centrifugal pump 2 is shortened by about 20%.

  Since the impeller rear chamber 23 communicates with the volute portion 41 as in the present embodiment, the water in the impeller rear chamber 23 is used as pressure water to which discharge pressure is applied without using any other device as a pressure source. It can be. Furthermore, by providing the impeller rear chamber 23 with a certain amount of capacity, during the self-priming operation, water supply from the volute 41 to the impeller rear chamber 23 through the gap S is suppressed to a minimum amount. The self-priming efficiency of the pump 2 can be further increased.

  By providing the return holes 38a and 38b in the center between the blades 32a and 32b, the fluid in the impeller rear chamber 23 is more smoothly moved to the front surface 35 side of the impeller 16 without hindering the pump operation by the impeller 16 as much as possible. Can be ejected.

  By recirculating a part of the fluid in the discharge chamber 22 in the casing 14 through the communication portion 24, the impeller 16 can always be immersed and the self-priming operation of the spiral pump 2 can be performed smoothly.

  The width of the gap S between the rear surface 36 of the impeller 16 and the front wall 19a of the casing cover 19 is preferably as small as possible. By narrowing the gap S, the energy loss of water sent from the volute 41 to the gas-liquid separation chamber 42, for example, the pressure loss, can be reduced. Furthermore, the gap S is preferably 2 mm or less.

  FIG. 9 shows the relationship between the gap S and the self-priming time. As shown in FIG. 9, when the width of the gap S is narrowed from 1.5 mm to 0.5 mm, the self-priming time is less than when the width of the gap S is narrowed from 3.5 mm to 1.5 mm. It turns out that it is not shortened. That is, what is important is to narrow the width of the gap S to near 1.5 mm, and considering the accuracy of processing and assembly, it is considered appropriate to narrow the gap S to about 2 mm. Therefore, it can be said that the self-priming time of the centrifugal pump 2 can be shortened by setting the width of the gap S to 2 mm or less.

  Note that the number of return holes 38a and 38b provided in the impeller 16 is not limited to two, and may be, for example, one or three or more. Further, the positions where the return holes 38a and 38b are provided are not particularly limited as long as they are on the surface of the main plate 31. The number of blades 32a and 32b of the impeller 16 is not limited to two, and the number is not limited. The spiral pump 2 is suitable for a pump having a total deadline of 12 m or less, but is not limited thereto. The working fluid of the spiral pump 2 is not limited to water, and any type can be used as long as it is a fluid.

The side view of the self-priming pump unit which concerns on embodiment of this invention. Sectional drawing of the spiral pump shown in FIG. The front view of the impeller shown in FIG. Sectional drawing which follows the AA line of the spiral pump shown in FIG. Sectional drawing which shows the state at the time of the starting start of the centrifugal pump shown in FIG. Sectional drawing which shows the state at the time of the self-priming operation of the spiral pump shown in FIG. Sectional drawing which shows the state at the time of the self-priming operation of the spiral pump shown in FIG. The figure which shows the relationship between the presence or absence of the return hole of the impeller shown in FIG. 2, and self-priming time. The figure which shows the relationship between the clearance gap between the impeller shown in FIG. 2, and a casing, and self-priming time.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Self-priming pump unit, 2 ... Spiral pump, 11 ... Suction port, 12 ... Discharge port, 14 ... Casing, 15 ... Motor, 16 ... Centrifugal impeller, 17 ... Installation stand, 18 ... Casing main body, 19 ... Casing Cover, 21 ... Suction chamber, 22 ... Discharge chamber, 23 ... Rear impeller chamber, 24 ... Communication portion, 31 ... Main plate, 32a. 32b ... blades, 35 ... front, 36 ... rear, 36a ... peripheral edge, 38a. 38b ... return hole, 45 ... first channel, 46 ... second channel.

Claims (5)

A casing, a motor, and a centrifugal impeller driven to rotate by the motor;
The centrifugal impeller has a main plate having a first surface and a second surface, and a plurality of blades attached to the first surface,
The casing has a suction port, a discharge port, a suction chamber that guides fluid from the suction port to a suction portion of the centrifugal impeller, and a discharge chamber that guides fluid from the discharge portion of the centrifugal impeller to the discharge port. In the type pump
The casing has a retention portion that retains pressure water to which discharge pressure is applied, between the second surface of the centrifugal impeller,
A self-priming pump characterized in that a hole penetrating from the first surface to the second surface opens in the main plate of the centrifugal impeller. The self-priming pump according to claim 1,
The self-priming pump, wherein the staying portion communicates with the discharge chamber. In the self-priming pump according to claim 1 or 2,
The self-priming pump, wherein the hole is opened at a center between the blades on the first surface of the main plate. In the self-priming pump according to claim 1 or 2,
The self-priming pump according to claim 1, wherein the casing further includes a communication portion that recirculates a part of the fluid flowing through the discharge chamber in the casing so as to immerse the centrifugal impeller. In the self-priming pump according to claim 1 or 2,
The self-priming pump, wherein a gap between a peripheral end portion of the second surface of the main plate and the casing is 2 mm or less.

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