JP5706792B2 - Centrifugal pump - Google Patents

Description

  The present invention relates to a centrifugal pump, and more particularly to a low specific speed centrifugal pump having a maximum efficiency point on the small water volume side.

  In general, a centrifugal pump is configured such that an impeller fixed to a rotating shaft that rotates as a motor is driven is rotatably disposed inside a casing, and the impeller is rotated so that fluid that has flowed into the casing is impeller driven. The pressure is increased by the rotation of and the gas flows out of the casing. Here, for example, a throttle part is provided at the outlet part of the casing, and the amount of water is throttled at the throttle part, or an orifice for restricting the water quantity is provided at the outlet of the casing so as to have the highest efficiency point on the low water quantity side. A low specific speed centrifugal pump is constructed.

  FIG. 1 shows a water volume-head curve X1 and an efficiency curve Y1 of a low specific speed centrifugal pump (specific low specific speed centrifugal pump) designed to achieve a maximum efficiency η1 with a water volume a1. In a low specific speed centrifugal pump, it is preferable to operate with a water amount as close as possible to the maximum efficiency η1 of the pump in order to reduce noise and vibration and to stabilize the pump mechanically. For this reason, for example, 80% of the maximum efficiency point water amount a1 is set to the minimum water amount a1 ′ (= a1 × 0.8), and for example, 110% is set to the maximum water amount a1 ″ (= a1 × 1.1). It is widely performed that this water amount range (a1 ′ to a1 ″) is defined as a pump operation water amount range A1.

  For this reason, if the specific low specific speed centrifugal pump is used to respond to the request for operation at the water amount a2 shown in FIG. 1, for example, out of the operating water amount range A1 of the specific low specific speed centrifugal pump, the water amount a2 The efficiency η2 of the specific low specific speed centrifugal pump in FIG. 3 is greatly deviated from the maximum efficiency point and considerably lower than the maximum efficiency η1, and noise and vibration may occur. Therefore, in such a case, the water amount-head curve X2 and the efficiency curve Y2 as shown by the broken line in FIG. 2 are provided, and the maximum efficiency is achieved with the water amount a2, or this water amount a2 is the operating water amount of the pump. A low specific speed centrifugal pump that is in the range A2 is widely used separately from a specific low specific speed centrifugal pump.

  As the impeller used for the low specific speed centrifugal pump having the highest efficiency point on the small water volume side, the applicant applies between the back surface of one blade (main wing) adjacent to each other and the surface of the other blade (main wing). An impeller provided with partitioning blades located inside the outer diameter of the impeller and extending from the back surface of one blade toward the surface of the other blade has been proposed (see Patent Document 1). In addition, a cylindrical auxiliary ring fitted to the outer peripheral portion of the impeller body having the first liquid passage is provided, and the second liquid passage extending from the inner peripheral portion to the outer peripheral portion of the auxiliary ring is provided in the auxiliary ring. The provided impeller is proposed (refer patent document 2).

JP 2007-51592 A Japanese Patent Laid-Open No. 2005-23794

  However, in order to respond to various requests from customers, designing and manufacturing a centrifugal pump that satisfies different performance each time increases design costs, manufacturing costs, material costs, etc., and increases the cost of the centrifugal pump itself. It will be connected. In addition, if the material is consumed in this way, it becomes a waste of limited resources. Even in the impellers described in Patent Documents 1 and 2, it is necessary to process the impeller itself according to the pump performance, and one impeller is required for a centrifugal pump having one performance. For this reason, a plurality of performances cannot be arbitrarily selected with one impeller.

For this reason, the applicant has proposed a centrifugal pump in which the maximum amount of water can be arbitrarily changed by a combination of one casing and one impeller as shown in FIGS. Application No. 2010-231069 (filing date October 14, 2010)). This centrifugal pump hermetically seals a casing 10 having a suction port 10a and a discharge port 10b, an impeller 12 that is rotatably accommodated in the casing 10, and an opening of the casing 10 that accommodates the impeller 12 therein. And a casing cover 14 to be used. The impeller 12 is connected to an end of a rotating shaft 16 that rotates as the motor rotates. The centrifugal pump further includes a guide plate 18 having a plurality of passages 18a, 18b, 18c, and 18d penetrating the impeller side and the casing side. The guide plate 18 is one passage in the plurality of passages. (e.g. passage 18a) only communicates with the discharge port 10b, the other path (e.g. passage 18b, 18c, 18 d) as is closed by the partition plate 20 in the impeller side, and the impeller 12 to the casing 10 They are arranged concentrically. Configuration Thus, communicates any one passageway in the plurality of passages 18a~18d the discharge port 10b, that is closing the other passage partition plate 20, the centrifugal pump arbitrarily change the amount of water maximum efficiency it can.

However, the centrifugal pump applicant proposed, although achieves the desired effect, communicates any one passageway in the plurality of passages 18a~18d the discharge port 10b, the blade while being closed other passages When the pump is driven by rotating the wheel 12, a force in one direction always acts on the impeller 12 and the right and left balance is deteriorated. For stable operation of the pump, for example, the rotating shaft or the rotating shaft is used. It has been found that it is necessary to use a highly rigid bearing to support, which leads to an increase in the size and cost of the pump.

  The present invention was made in view of the above circumstances, and by combining a single casing and a single impeller, the maximum amount of water can be arbitrarily changed, and a preferred operating water volume range can be arbitrarily selected and configured. And it aims at providing the centrifugal pump which rotated the impeller with sufficient balance and was able to perform the stable driving | operation.

  The invention according to claim 1 is an impeller that is connected to a rotating shaft and rotates, a casing that has a discharge port and accommodates the impeller therein, a casing cover that seals an opening of the casing, A plurality of a set of passages that pass through the impeller side and the casing side are located at positions that substantially coincide with each other when rotated by an angle, and a guide passage that communicates with the discharge port is formed between the casing and the casing. A guide plate disposed concentrically with the impeller in the casing, and a closing member that closes the other passage on the impeller side while leaving one set of the plurality of passages. It is a centrifugal pump characterized by having.

  Thus, for example, a position that substantially coincides when the guide plate is rotated by a predetermined angle (a position that substantially coincides when the guide plate is rotated 180 ° about the axis of the rotation shaft (substantially point symmetrical position) or a guide plate When there are two sets of passages positioned at substantially the same position when rotated by 120 °, one set of passages of the guide plate communicates with the discharge port of the casing through the guide passage, and the other set of passages. The first centrifugal pump is configured so that the passages of the guide plate are closed by the closing member, the other set of passages of the guide plate communicate with the discharge port of the casing through the guide passage, and the one set of passages is the closing member. A second centrifugal pump having a performance different from that of the first centrifugal pump can be configured so as to be closed. In the first centrifugal pump and the second centrifugal pump, when the impeller is rotated to drive the pump, the fluid is guided through a pair of passages located at substantially the same positions when the guide plate is rotated by a predetermined angle. Since it flows into the interior and is discharged from the discharge port, force in multiple directions acts on the impeller more evenly, and these forces cancel each other out, improving the balance between the left and right, and rotating the impeller in a balanced manner Stable operation can be performed.

  The invention according to claim 2 is characterized in that the guide plate is disposed in the casing so as to be rotatable in the circumferential direction and is fixed to the casing or the casing cover. It is.

  Accordingly, when the guide plate is arranged and fixed to the casing or the casing cover so that the other passage is closed by the closing member while leaving one set of the plurality of sets of passages provided in the guide plate, the guide By rotating the plate in the circumferential direction, the arrangement of the guide plate with respect to the casing or the casing cover can be easily adjusted.

  According to a third aspect of the present invention, at least some of the passages constituting the set of passages of the guide plate have different cross-sectional areas. This is a centrifugal pump.

  Each of the passages constituting a pair of passages of the guide plate preferably has substantially the same cross-sectional area, although it is preferable for stable operation by rotating the impeller in a balanced manner. You don't have to.

  According to a fourth aspect of the present invention, the closing member is configured by an arc-shaped partition plate inscribed on the impeller side of the guide plate, and the partition plate is integrally formed with the casing cover. A centrifugal pump according to any one of claims 1 to 3, wherein

  Thereby, for example, when the guide plate is fixed to the casing, the relative position between the guide plate and the partition plate can be changed by relatively rotating the casing and the casing cover, and the casing cover and the partition plate can be changed. Is easy to install.

According to a fifth aspect of the present invention, the partition plate has a thickness along the fluid flow direction in the flow path so that a flow path serving as a volute is formed between the partition plate and the outer peripheral end surface of the impeller. The centrifugal pump according to claim 4, wherein the centrifugal pump is formed in a decreasing shape.
Thereby, a fluid can flow more smoothly along the flow path used as the volute formed between the outer peripheral end surface of an impeller and a partition plate.

  The invention according to claim 6 is characterized in that the guide passage is formed in a region sandwiched between a flange portion provided in the guide plate and the casing cover. The described centrifugal pump.

  According to a seventh aspect of the present invention, in any one of the first to fifth aspects, the guide passage is formed in a concave groove provided on a surface of the casing facing the outer peripheral end surface of the guide plate. It is a centrifugal pump as described above.

The invention according to claim 8 is characterized in that the guide passage has a volute shape in which the cross-sectional area of the flow path gradually increases along the flow direction of the fluid flowing in the guide passage. The described centrifugal pump.
Thereby, the fluid can flow more smoothly along the guide passage formed in a volute shape between the casing and the guide plate.

According to the ninth aspect of the present invention, a flow stop is disposed in the vicinity of the discharge port of the guide passage to prevent fluid flowing through the guide passage and discharged from the discharge port from flowing into the guide passage. The centrifugal pump according to claim 6 or 7, wherein the centrifugal pump is provided.
As a result, the fluid flowing along the guide passage is blocked by the flow stopper, and all of the fluid flowing along the guide passage can be sequentially discharged from the discharge port.

  According to the centrifugal pump of the present invention, the centrifugal pump can be configured while arbitrarily selecting a preferable operating water amount range by arbitrarily changing the maximum amount of water by combining one casing and one impeller. . In addition, when the centrifugal pump configured in this manner rotates the impeller and drives the pump, forces in a plurality of directions are more evenly applied to the impeller, and these forces cancel each other, and the left and right The balance is improved, and the impeller can be rotated in a well-balanced manner to perform stable operation.

  This eliminates the need to design and manufacture centrifugal pumps for each amount of water used by customers, eliminates waste of materials, etc., reduces cost of centrifugal pumps, and eliminates wasteful use of valuable earth resources. It can lead to energy saving. In particular, by rotating the impeller in a well-balanced manner and performing a stable pump operation, for example, a rotating shaft and a bearing that supports the rotating shaft can be used with a low rigidity, thereby reducing the size of the pump. Therefore, the manufacturing cost and material cost can be further reduced.

  In addition, a centrifugal pump with a small amount of water and a high head that employs a general centrifugal pump structure generally has a small exit passage area, and when trying to obtain a casing by casting, the passage may not be reliably molded in the casing. However, since the guide plate used in the centrifugal pump of the present invention, which is provided with a passage that determines pump performance, has an open passage, it can be molded relatively easily by casting.

It is a graph which shows the water quantity-head curve and efficiency curve of one low specific speed centrifugal pump. It is a graph which shows the water volume-lift curve and efficiency curve of another low specific speed centrifugal pump with the water volume-lift curve and efficiency curve shown in FIG. It is a vertical front view of the centrifugal pump which the applicant proposed in the previous application (Japanese Patent Application No. 2010-231069). FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a vertical front view of the centrifugal pump of the embodiment of the present invention. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is the FIG. 5 equivalent view of the centrifugal pump of other embodiment of this invention. FIG. 7 is a view corresponding to FIG. 6 of a centrifugal pump according to still another embodiment of the present invention. FIG. 7 is a view corresponding to FIG. 6 of a centrifugal pump according to still another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following examples, the same or corresponding members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 5 is a longitudinal front view of the centrifugal pump according to the embodiment of the present invention, and FIG. 6 is a sectional view taken along line BB of FIG. As shown in FIGS. 5 and 6, the centrifugal pump includes a casing 30 having a suction port 30 a and a discharge port 30 b, an impeller 32 that is rotatably accommodated inside the casing 30, and an impeller 32 inside. A casing cover 34 for sealing the opening of the accommodated casing 30 is provided. The casing cover 34 is fixed to the casing 30 via bolts 36.

  The impeller 32 is fixed to the end portion on the casing 30 side of the rotary shaft 46 rotatably supported by bearings 42 and 44 incorporated in a bearing body 40 connected to the casing cover 34. The other end of the rotating shaft 46 extends from the bearing body 40 to the outside and is connected to a motor (not shown). Thereby, the impeller 32 rotates integrally with the rotating shaft 46 as the motor is driven.

  In this example, the impeller 32 is configured by radially arranging a plurality of blades 52 extending linearly on the surface of a disk-shaped main plate (hub) 50. The shape of the impeller is not limited to this configuration, and various impellers such as a closed type, an open type, and a semi-open type can be applied depending on the application.

  The inner surface of the casing 30 on the side of the impeller 32 has a ring-shaped protrusion 54a surrounding the impeller 32 and a flange 54b extending outward from the protrusion 54a. The guide plate 54 is arranged concentrically with the impeller 32 so as to be rotatable in the circumferential direction, the protruding end surface of the protruding portion 54a of the guide plate 54 contacts the casing cover 34, and the outer peripheral end surface of the flange portion 54b contacts the casing 30. In this state, it is fixed to the casing 30 via a bolt 56. As a result, a circumferentially continuous flow path 58 is formed between the outer peripheral end face of the impeller 32 and the protrusion 54a of the guide plate 54, which is located in a region sandwiched between the casing 30 and the casing cover 34. A circumferentially continuous guide passage 60 is formed between the protrusion 54 a of the guide plate 54 and the casing 30.

  In this example, the guide plate 54 is fixed to the casing 30 with bolts 56, but the guide plate 54 may be fixed to the casing cover 34 with bolts or the like.

  The guide plate 54 extends in the tangential direction of the flow path 58, passes through the impeller 32 side and the casing 30 side, and connects the flow path 58 and the guide passage 60. In this example, a first pair of passages 62 a, 62b and the second pair of passages 64a, 64b are provided with two pairs of passages, and only one of the pair of passages is used as a passage, and the other pair of passages is It is supposed to be blocked. The first pair of passages 62a and 62b rotate the guide plate 54 approximately 180 ° around the center of the guide plate 54 that coincides with the center O of the rotation shaft 46 at a substantially point-symmetrical position of the guide plate 54. Similarly, the second pair of passages 64a and 64b are located at substantially point-symmetrical positions of the guide plate 54, that is, around the center of the guide plate 54 that coincides with the axis O of the rotation shaft 46. 54 is provided at a position rotated approximately 180 °.

  These passages 62a, 62b, 64a, and 64b are open to the casing cover 34 side, and are a line that connects the first pair of passages 62a and 62b to each other and a line that connects the second pair of passages 64a and 64b to each other. The formed angle is set to 90 °. The number of passages provided in the guide plate may be a plurality of pairs.

  The guide plate 54 having such a shape is formed with two pairs of passages 62a, 62b, 64a, and 64b having a predetermined shape that determine pump performance, but these passages 62a, 62b, 64a, and 64b are formed on the casing cover 34. Since it opens to the side, it can be molded relatively easily by casting.

As shown in FIG. 6, for example, when the first pair of passages 62a and 62b is used as a passage connecting the flow path 58 and the guide passage 60, the second pair of passages 64a and 64b is not used as a passage. Therefore, a position for closing the second pair of passages 64a that are not used as a passage, and 64b in the impeller 3 2 side, a pair of partition constituting a closure member for closing the second pair of passages 64a, 64b, respectively A plate 70 is provided.

  In this example, each partition plate (closing member) 70 is formed of an arc-shaped plate that is inscribed in the inner peripheral surface of the protrusion 54 a of the guide plate 54 and is provided integrally with the casing cover 34. Thus, for example, in the state shown in FIG. 6, the guide plate 54 fixed to the casing 30 is rotated 90 ° clockwise with respect to the casing cover 34, whereby the partition plates 70 of the second pair of passages 64 a and 64 b. The second pair of passages 64a and 64b is used as a passage connecting the flow path 58 and the guide passage 60, and the first pair of passages 62a and 62b are closed by the partition plate 70. It is like that.

Furthermore, in this example, as the partition plate 70, so as to form a volute passage 58 formed frontage spread in the direction of flow of water between the outer peripheral end face and the partition plate 70 of the impeller 3 2, the fluid The one whose thickness is gradually reduced toward the flow direction is used. That is, the thickness t1 of the end portion located upstream of the partition plate 70 in the fluid flow direction is larger than the thickness t2 of the end portion located downstream (t1> t2).

  The sizes of the passage portions of the first pair of passages 62a and 62b and the second pair of 64a and 64b determine different pump performances in the first pair of passages 62a and 62b and the second pair of 64a and 64b. Is set to be able to. That is, the size of the passage portion of the first pair of passages 62a and 62b is such that the first pair of passages 62a and 62b are used as passages, and the second pair of passages 64a and 64b are closed by the partition plate 70. When the first centrifugal pump is configured, the water amount-lifting curve and the efficiency curve of the first centrifugal pump coincide with, for example, the water amount-lifting curve X1 and the efficiency curve Y1 shown in FIG. It is set to become.

  The size of the passage portion of the second pair of passages 64a and 64b is such that the second pair of passages 64a and 64b are used as passages, and the first pair of passages 62a and 62b are closed by the partition plate 70. When two centrifugal pumps are configured, the water amount-lifting curve and the efficiency curve of the second centrifugal pump coincide with, for example, the water amount-lifting curve X2 and the efficiency curve Y2 shown in FIG. 2 and become the maximum efficiency point at the water amount a2. Is set to

  In this example, the passages 62a and 62b constituting the first pair of passages have substantially the same shape (cross-sectional area). Similarly, each of the passages 64a and 64b constituting the second pair of passages has substantially the same shape. As described above, it is preferable to use a passage having substantially the same shape as each passage constituting the pair of passages in order to perform a stable operation by rotating the impeller 32 in a balanced manner.

In this example, one pair of passages 62a, 62b, 64a, 64b provided in the guide plate 54 is used as a passage connecting the passage 58 and the guide passage 60, and the other pair of passages. Are closed by the partition plate 70 to form a centrifugal pump, thereby obtaining two types of centrifugal pumps having different water amount-lift curves and performance curves. Thereby, the newly designed centrifugal pump, without fabricating a new centrifugal pump, using one of the casing 3 0 and one of the impeller 3 2, simply the relative position of the guide plate 54 and the partition plate 70 By changing, centrifugal pumps having different water volume-head curves and performance curves can be configured.

  In this example, two pairs of passages are provided, and by closing the pair of passages, a centrifugal pump having two different water volume-lift curves and performance curves can be configured. A centrifugal pump having three different water volume-lift curves and performance curves may be configured by providing a passage and closing two pairs of the three pairs of passages.

  For example, as shown in FIG. 6, the first pair of passages 62 a and 62 b is used as a passage connecting the flow path 58 and the guide passage 60, and the second pair of passages 64 a and 64 b are closed by the partition plate 70. Then, when the first centrifugal pump is configured and the impeller 32 is rotated to drive the pump, as the impeller 32 rotates, the fluid sucked from the suction port 30a and pressurized is supplied from the flow path 58. The guide plate 54 flows into the guide passage 60 through the first pair of passages 62a and 62b provided at substantially point-symmetrical positions, and is discharged from the discharge port 30b. As a result, forces in two directions at substantially point-symmetrical positions about the axis O of the rotation shaft 46 act on the impeller 32, and these forces cancel each other to improve the left and right balance, thereby improving the impeller 32. Can be rotated in a well-balanced manner for stable operation.

  This is because the second pair of passages 64a and 64b is used as a passage connecting the flow passage 58 and the guide passage 60, and the first pair of passages 62a and 62b are closed by the partition plate 70. The same applies to the pump.

  Thus, by rotating the impeller 32 in a well-balanced manner and performing a stable pump operation, for example, the rotating shaft 46 and the bearings 42 and 44 that support the rotating shaft 46 can be used with low rigidity. In this way, the pump can be miniaturized and the manufacturing cost and material cost can be further reduced.

  In the above example, the first pair of passages 62a and 62b and the second pair of passages 64a and 64b are provided at substantially point symmetrical positions of the guide plate 54, respectively, and the guide plate 54 fixed to the casing 30 is provided. One pair of passages 62a and 62b or 64a and 64b is selectively used as a passage by rotating clockwise by 90 ° with respect to the casing cover 34, but the guide plate is rotated by a predetermined angle. A first set (three) of passages and a second set (three) of passages are provided at positions that are sometimes substantially coincident, for example, coincident when the guide plate is rotated 120 °, and are fixed to the casing. One set of passages is selectively used as a passage (the other set) by rotating the guide plate rotated clockwise by 60 ° with respect to the casing cover. Passage may be a partition plate closing) as a. The same applies to the following examples.

  This also makes it possible to perform a stable operation by causing forces in a plurality of directions to be applied evenly by the impeller, offsetting these forces to improve the left and right balance, and rotating the impeller in a balanced manner.

  FIG. 7 shows a centrifugal pump according to another embodiment of the present invention. FIG. 7 shows a state where the passage 64 a is closed by the partition plate 70. The example shown in FIGS. 5 and 6 differs from the example shown in FIGS. 5 and 6 in that the guide plate 54 is provided with a flange portion 54b and is sandwiched between the flange portion 54b and the casing cover 34. In this example, the guide plate 54 is not provided with a flange portion, but the groove 30c is provided on the surface of the casing 30 facing the outer peripheral end surface of the guide plate 54, and the concave portion 30c is provided. The guide passage 60 is formed inside the recessed groove 30c by closing the opening of the groove 30c with the protrusion 54a of the guide plate 54. In this example, the guide passage 60 is formed along the shape of the concave groove 30 c provided in the casing 30.

  FIG. 8 shows a centrifugal pump according to still another embodiment of the present invention. 5 and 6 of this example is different from the example shown in FIGS. 5 and 6 in that the fluid that flows in the guide passage 60 and is discharged from the discharge port 30b in the vicinity of the discharge port 30b of the casing 30 of the guide passage 60 that extends in a ring shape. A flow stop 72 is provided for preventing the flow into the guide passage 60. As a result, the entire amount of fluid flowing along the guide passage 60 can be sequentially discharged from the discharge port 30 b of the casing 30. A surface 72a continuous to the discharge port 30b of the flow stop 72 is formed in a shape along the flow of the fluid so that the fluid flows smoothly along the surface 72a.

  Further, in this example, the passages 62a and 62b constituting the first pair of passages have different shapes (cross-sectional areas). Similarly, each of the passages 64a and 64b constituting the second pair of passages has a different shape. As described above, it is ideal to use substantially the same shape as each of the passages constituting the pair of passages, but it is not always necessary to have substantially the same shape.

  FIG. 9 shows a centrifugal pump according to still another embodiment of the present invention. 5 and FIG. 6 of this example is different from the example shown in FIGS. 5 and 6 in that the thickness of the protrusion 54a of the guide plate 54 gradually decreases along the fluid flow direction. A volute-shaped guide passage 60 is formed between the casing 30 and the casing 30 so that the flow path cross-sectional area gradually increases along the fluid flow direction.

  Thus, by making the guide passage 60 formed between the casing 30 and the protrusion 54a of the guide plate 54 into a volute shape in which the flow path cross-sectional area gradually increases along the fluid flow direction, The fluid can flow more smoothly along the guide passage 60.

  In the example shown in FIG. 8, the flow stop 72 is disposed inside the guide passage 60 formed in the region sandwiched between the flange portion 54b of the guide plate 54 and the casing cover 34. As shown, when the guide channel 60 is formed by the concave groove 30c provided in the casing 30, a flow stop may be disposed inside the concave groove 30c. Further, in the example shown in FIG. 9, a volute-shaped guide passage 60 is formed in a region sandwiched between the flange portion 54b of the guide plate 54 and the casing cover 34. As shown in FIG. In the case where the guide channel 60 is formed by the concave groove 30c provided in 30, the shape of the concave groove 30c forming the guide passage may be a volute shape.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

30 Casing 30a Suction port 30b Discharge port 32 Impeller 34 Casing cover 40 Bearing body,
42, 44 Bearing 46 Rotating shaft 50 Main plate 52 Blade 54 Guide plate 54a Projection 54b Flange 58 Flow path 60 Guide passages 62a, 62b, 64a, 64b Passage 70 Partition plate 72 Flow stop

Claims (9)

An impeller connected to a rotating shaft and rotating;
A casing having a discharge port and containing the impeller inside;
A casing cover for sealing the opening of the casing;
A plurality of sets of passages that pass through the impeller side and the casing side are located at substantially the same position when rotated by a predetermined angle, and a guide passage communicating with the discharge port is formed between the casing and the casing. A guide plate disposed concentrically with the impeller in the casing,
A centrifugal pump, comprising: a closing member that closes one of the plurality of sets of passages and closes the other passage on the impeller side.   The centrifugal pump according to claim 1, wherein the guide plate is disposed in the casing so as to be rotatable in a circumferential direction and is fixed to the casing or the casing cover.   3. The centrifugal pump according to claim 1, wherein at least some of the passages constituting the set of passages of the guide plate have different cross-sectional areas.   The said closing member is comprised by the circular arc-shaped partition plate inscribed in the impeller side of the said guide plate, This partition plate is integrally molded with the said casing cover. A centrifugal pump according to any one of the above.   The partition plate is formed in a shape whose thickness decreases along the flow direction of the fluid in the flow path so that a flow path serving as a volute is formed between the outer peripheral end surface of the impeller. The centrifugal pump according to claim 4.   The centrifugal pump according to claim 1, wherein the guide passage is formed in a region sandwiched between a flange portion provided in the guide plate and the casing cover.   The centrifugal pump according to any one of claims 1 to 5, wherein the guide passage is formed in a concave groove provided on a surface of the casing facing the outer peripheral end surface of the guide plate.   The centrifugal pump according to claim 6 or 7, wherein the guide passage has a volute shape in which a flow path cross-sectional area gradually increases along a flow direction of a fluid flowing in the guide passage.   A flow stop for preventing fluid flowing through the guide passage and discharged from the discharge port from flowing into the guide passage is disposed near the discharge port of the casing of the guide passage. The centrifugal pump according to claim 6 or 7.

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