JP4065872B2 - Centrifugal impeller and fluid machinery - Google Patents

Description

  The present invention relates to a centrifugal impeller used in a fluid machine such as a water turbine including a pump, a compressor, and a pump reversing water turbine.

  Centrifugal impellers are widely used in various fluid machines, and various attempts have been made to improve their performance (see, for example, Patent Document 1).

  Recently, demands for performance adjustment of centrifugal impellers are increasing from the viewpoint of energy saving. As a method for adjusting the performance of a centrifugal pump provided with a centrifugal impeller when the rotational speed is constant, it is known to firstly provide a control valve whose opening degree can be adjusted in a pipe on the discharge side of the centrifugal pump. Further, as a second method, it is known that the outer diameter of the centrifugal impeller is reduced by processing.

  However, the first method has a problem in that a loss is caused by providing the control valve in the pipeline itself, resulting in a decrease in efficiency.

Further, the second method has the following problems. Referring to FIG. 15 showing the performance curve of the centrifugal pump, η ₁ ′ and η ₂ ′ are efficiency, H ₁ ′ and H ₂ ′ are head curves (HQ curves), and N ₁ ′ and N ₂ ′ are suction actuals. The head (NPSH) is shown. The solid performance curves η ₁ ′, H ₁ ′, N ₁ ′ indicate the case where the diameter of the centrifugal impeller is D1, and the dotted performance curves η ₂ ′, H ₂ ′, N ₂ ′ indicate the centrifugal impeller. A case where the diameter D2 (D2 <D1) is obtained by performing processing to reduce the outer diameter is shown.

In adjusting the performance of the centrifugal impeller, it is preferable to change only the lift at the operating flow rate (for example, the flow rate Q _{1 in} FIG. 15) and maintain the deadline lift (the lift when the flow rate is zero). However, when the outer diameter of the centrifugal impeller is reduced, as is clear when the head curves H ₁ ′ and H ₂ ′ are compared, not only the head falls in the flow rate region near the working flow rate Q ₁ but also the cutoff head. Decrease significantly. Further, as apparent from comparing the efficiency η ₁ ′ and η ₂ ′, when the outer diameter of the centrifugal impeller is reduced, the maximum efficiency point changes greatly. Further, as is clear from the comparison of the actual suction heads N ₁ ′ and N ₂ ′, when the outer diameter of the centrifugal impeller is reduced, the suction performance also changes. Furthermore, processing for reducing the outer diameter of the centrifugal impeller is relatively easy, but it is difficult to increase the outer diameter by processing. Therefore, the second method can be adjusted to reduce the lift, but cannot be adjusted to increase the lift. In view of the above, the second method has a low degree of freedom in performance adjustment.

  It is known that the axial flow impeller and the mixed flow impeller are movable blades for performance adjustment. However, this type of movable blade is a mechanism that adjusts the blade angle by moving the entire individual blade, and thus cannot be applied to a centrifugal impeller.

JP-A-7-54796

  An object of the present invention is to provide a centrifugal impeller capable of realizing performance adjustment with a high degree of freedom while suppressing loss.

  According to the present invention, a plurality of blades are arranged on the side wall plate in a blade row, the inlet is positioned on the rotation center side of the side wall plate, and the outlet is positioned on the outer peripheral side of the side wall plate, and the corresponding blades A centrifugal impeller comprising a plurality of auxiliary blades extending along an outer periphery of the side wall plate from an outlet toward a direction opposite to a rotation direction of the side wall plate.

  The exit angle of the blade and the blade angle of the auxiliary blade are different.

  The impeller of the present invention can perform performance adjustment by adjusting the blade length of the auxiliary blade. Moreover, since it is not necessary to process a blade | wing for performance adjustment, the freedom degree of performance adjustment is high. Furthermore, since it is not necessary to provide a control valve for performance adjustment in the pipe line, loss can be suppressed.

  In the present specification, the blade length of the auxiliary blade is defined as the length from the end of the blade on the upstream side in the rotation direction to the tip of the auxiliary blade on the outer periphery of the side plate. The blade angle of the auxiliary wing is defined as an angle formed by the direction in which the auxiliary wing extends at the tip of the auxiliary wing and the tangential direction of the outer periphery of the side wall plate at the tip of the auxiliary wing.

  More specifically, the auxiliary wing is separate from the blade and is detachably fixed to the side wall plate. The performance can be adjusted by replacing the auxiliary blades with different blade lengths.

  As an alternative, the auxiliary wing is separate from the blade, and the centrifugal impeller includes an adjustment mechanism that adjusts the angular position of the auxiliary wing around the rotation center of the side wall plate. By adjusting the angular position around the rotation center of the side wall plate of the auxiliary wing with the adjusting mechanism, the blade length of the auxiliary wing can be changed, and performance adjustment can be performed easily and with a high degree of freedom.

  Specifically, the adjusting mechanism is provided with the auxiliary wing and attached to the outer periphery of the side wall plate, and the pair of frame bodies can be released with respect to the outer periphery of the side wall plate. Tightening means for tightening each other. If the tightening means is loosened, the angular position of the frame body around the rotation center of the side wall plate can be adjusted, thereby changing the blade length of the auxiliary wing. If the outer periphery of the side wall plate is tightened with a pair of frames by the tightening means, the angular position of the frame can be fixed.

  As an alternative, the adjusting mechanism is provided with the auxiliary wings, can move forward and backward in the direction along the rotation center of the side wall plate with respect to the side wall plate, and is around the rotation center of the side wall plate with respect to the side wall plate. An auxiliary wing holding member rotatably attached to the side wall plate, a moving means for moving the auxiliary wing holding member forward and backward in a direction along the rotation center of the side wall plate, and along the rotation center. A cam mechanism that changes an angular position of the auxiliary wing holding member around the rotation center in accordance with a position in the direction. When the auxiliary wing holding member is advanced or retracted in the direction along the rotation center by the moving means, the angular position of the auxiliary wing holding member around the rotation center of the side wall plate is changed by the cam mechanism, so the blade length of the auxiliary wing can be changed. it can. When the auxiliary blade holding member is positioned in a direction along the rotation center of the side wall plate, the angular position around the rotation center of the auxiliary blade holding member can be fixed.

  The moving means includes, for example, a screw mechanism or a hydraulic cylinder. The cam mechanism includes, for example, a cam groove extending at an angle with respect to the rotation center formed in the auxiliary blade holding member, and a cam on the side wall plate side disposed in the cam groove. The auxiliary wing may be integrated with the blade.

  The centrifugal impeller of the present invention can be used for various fluid machines such as a centrifugal pump, a centrifugal compressor, and a water turbine including a pump reverse rotation turbine. If the centrifugal impeller of the present invention is used for the centrifugal pump, the lift at the working flow rate can be adjusted without changing the efficiency and suction performance and without changing the cutoff lift. Moreover, if the auxiliary wings are made detachable, both the increase and decrease of the head can be performed depending on the presence or absence of the auxiliary wings.

  Since the centrifugal impeller of the present invention includes auxiliary blades extending along the outer periphery of the side wall plate from the blade outlet toward the opposite side of the side wall plate in the rotation direction, performance adjustment is performed by adjusting the length of the auxiliary blade. It can be performed. Moreover, since it is not necessary to process a blade | wing for performance adjustment, the freedom degree of performance adjustment is high. Furthermore, since it is not necessary to provide a control valve for performance adjustment in the pipe line, loss can be suppressed.

  If the centrifugal impeller of this invention is used for a centrifugal pump, a lift can be adjusted, without changing efficiency, suction performance, and a deadline lift.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
The first embodiment of the present invention shown in FIGS. 1 to 4 is an example in which the present invention is applied to a centrifugal impeller (hereinafter simply referred to as “impeller”) 2 of a double-suction centrifugal pump 1 on a horizontal axis. .

  Referring to FIG. 1, the double suction centrifugal pump 1 includes a casing 3 including an upper casing 3 </ b> A and a lower casing 3 </ b> B, and a spiral chamber 4 is formed in the casing 3. The impeller 2 disposed in the spiral chamber 4 is fixed to a main shaft 5 extending in the horizontal direction in the drawing. The main shaft 5 extends through the casing 3. A pair of bearing brackets 6A and 6B is fixed to the lower casing 3B, and both ends of the main shaft 5 are rotatably supported by bearings 7A and 7B accommodated in the bearing brackets 6A and 6B. In addition, sealing mechanical seals 8A and 8B are disposed at portions where the main shaft 5 penetrates the casing 3. In the drawing of the main shaft 5, the right end is connected to a prime mover (not shown).

  When the main shaft 5 is rotationally driven by the prime mover, the impeller 2 rotates in the spiral chamber 4. The water flowing into the spiral chamber 4 from the suction port 9 flows into the rotating impeller 2 from the impeller inlets 10A and 10B, and is discharged from the impeller outlet 11 through the discharge port 12.

  Referring to FIGS. 1 to 3, the impeller 2 includes a boss portion 15 that is fixed to the main shaft with a key, and a main plate (side wall plate) 16 that extends from the boss portion 15 in the radial direction of the main shaft 5. To the main plate 16, the base end sides of a plurality of both suction type blades 17 are fixed. Further, the left and right ends of the plurality of blades 17 are connected by side plates (side wall plates) 18A and 18B. The outer periphery of the main plate 16 is circular. Further, the side plates 18A and 18B have a circular outer periphery 18a, and the central openings constitute the impeller inlets 10A and 10B. Further, the portion sandwiched between the outer peripheries 18a of the side plates 18A and 18B facing each other constitutes the impeller outlet 11. The main plate 16 and the side plates 18A and 18B are arranged coaxially with the main shaft 5. Therefore, the rotation center L of the main shaft 5 is also the rotation center of the main plate 16 and the side plates 18A and 18B.

  As shown in FIG. 2, the blades 17 are arranged in a cascade with respect to the side plates 18A and 18B. The inlets 17a of the individual blades 17 are located at the impeller inlets 10A and 10B (the rotation center L side of the side plates 18A and 18B), and the outlet 17b is located at the impeller outlet 11 (the outer peripheral side 18a side of the side plates 18A and 18B).

  As shown most clearly in FIG. 2, an auxiliary wing 20 is provided for each blade 17. The auxiliary blade 20 extends from the outlet 17b of the blade 17 along the outer periphery of the side plates 18A and 18B. Further, the auxiliary wing 20 extends toward the side opposite to the rotation direction of the main shaft 5 around the rotation center L indicated by the arrow R in FIG. Referring also to FIG. 3, like the blade 17, the left and right tips in the drawing of the auxiliary wing 20 are connected to the side plates 18 </ b> A and 18 </ b> B.

  In this embodiment, each auxiliary wing 20 and the blade | wing 17 corresponding to it are separate bodies. Further, the auxiliary wing 20 is separate from the side plates 18A and 18B. As shown in FIGS. 3 and 4, the auxiliary wing 20 is fixed to the side plates 18 </ b> A and 18 </ b> B by bolts 23. Therefore, the auxiliary blade 20 can be easily removed from the impeller 2. In addition, the auxiliary wings 20 having different shapes and dimensions can be easily replaced.

  Next, with reference to FIG. 4, the cross-sectional shape of the auxiliary blade 20 in a cross section orthogonal to the rotation center L will be described. First, the base end surface 20 a of the auxiliary wing 20 is in close contact with the inner surface 17 c of the corresponding blade 17. On the other hand, the tip surface 20b of the auxiliary blade 20 has an arc shape with a small radius of curvature. Next, the outer surface 20c of the auxiliary wing 20 located on the impeller outlet 11 side (the outer periphery 18a side of the side plates 18A and 18B) has an arc shape that matches the outer periphery of the side plates 18A and 18B. On the other hand, the inner side surface 20d of the auxiliary blade 20 positioned on the impeller inlet 10A, 10B side has an arc shape with a smaller radius of curvature than the outer side surface 20c, and smoothly joins the inner surface 17c of the blade 17.

  A distance α1 along the outer circumferential direction of the side plates 18A, 18B from the intersecting position P1 of the outer surface 17d of the blade 17 and the outer peripheries of the side plates 18A, 18B to the tip surface 20b of the auxiliary blade 20 is referred to as a blade length. Further, the distance α2 along the circumferential direction of the side plates 18A, 18B from the intersecting position P2 between the inner surface 17c of the blade 17 and the outer peripheries of the side plates 18A, 18B to the tip surface 20d of the auxiliary blade 20 is referred to as a protrusion amount. As described later in detail, the performance of the impeller 2 can be adjusted with a high degree of freedom by changing the blade length α1 and the protrusion amount α2 of the auxiliary blade 20.

The extending direction of the auxiliary blade 20 is different from the exit angle β 1 of the blade 17. In FIG. 4, symbol β <b> 1 indicates the exit angle of the blade 17. This exit angle β1 is defined as an angle formed by the direction in which the blade 17 extends at the impeller outlet 11 and the tangential direction of the side plates 18A and 18B. Symbol β2 represents the blade angle of the auxiliary blade 20. The blade angle β2 is defined as an angle formed by the outer surface 20c of the auxiliary blade 20 and the outer periphery of the side plates 18A and 18B at the impeller outlet 11. In the present embodiment, the blade angle β2 is 0 °. It is necessary to set the blade angle β2 to an angle different from the exit angle β1.

  Next, the reason why the lift of both suction type centrifugal pumps 1 can be adjusted by the auxiliary blade 20 will be described theoretically with reference to FIG. The following theoretical explanation also applies to the case of the single suction centrifugal pump 31 as in the second embodiment described later. In the velocity triangle of FIG. 5, the solid line indicates the case where the auxiliary wing 20 is not provided, and the dotted line indicates the case where the auxiliary wing 20 is provided.

  In FIG. 5, symbol U represents a circumferential speed component (circumferential speed of the outer periphery 18a of the side plates 18A and 18B) at the impeller outlet 11. Symbols C and C 'are absolute velocity of water flow. Further, symbols Cu and Cu ′ are circumferential velocity components of the absolute velocity of the water flow at the impeller outlet 11. Furthermore, the symbols W and W ′ represent the relative velocity of the water flow with respect to the impeller 2. Symbols γ and γ ′ indicate angles (flow angles) formed by the relative velocities W and W ′ in the circumferential direction. Symbols C, Cu ′, and γ are speeds when the auxiliary blade 20 is not provided, and symbols C, Cu ′, and γ are speeds when the auxiliary blade 20 is provided. The symbol Cm is a velocity component in a direction orthogonal to the circumferential direction of the absolute velocity of the water flow, and is constant regardless of the presence or absence of the auxiliary blade 20.

The theoretical head Hth when the auxiliary blade 20 is not provided is given by the following equation (1). The symbol g is the gravitational acceleration.

  By providing the auxiliary blade 20, the flow angle decreases from γ to γ ′, and accordingly, the circumferential velocity component of the absolute velocity of the flow also decreases from Cu to Cu ′. The theoretical head Hth ′ when the auxiliary blade 20 is provided is given by the following equation (2).

  As described above, since Cu ′> Cu, as is clear from the equations (1) and (2), when the auxiliary blade 20 is provided, the theoretical head is lowered. The reduction rate a of the theoretical head is given by the following formula (3).

As apparent from the equation (3), the lower the circumferential velocity component Cu ′ of the absolute flow velocity, the lower the lift. Also, the longer the blade length α1 of aileron 20 ailerons, the flow angle of gamma 'becomes smaller, the circumferential velocity component Cu' decreases. Accordingly, the lift height decreases as the blade length α1 of the auxiliary blade 20 increases. In other words, the head can be freely set by setting the blade length α1 of the auxiliary blade 20.

FIG. 6 schematically shows performance curves of the double suction centrifugal pump 1. In FIG. 6, η ₁ and η ₂ are efficiency, H ₁ and H ₂ are lift curves (HQ curves), and N ₁ and N ₂ are actual suction lifts. The solid performance curves η ₁ , H ₁ , and N ₁ indicate the case where the auxiliary blade 20 is not provided, and the dotted performance curves η ₂ ′, H ₂ ′, and N ₂ ′ indicate the case where the auxiliary blade 20 is provided. . Furthermore, let the used flow rate be Q1.

As is apparent from the comparison of the lift curves H ₁ and H ₂ , the provision of the auxiliary blades 20 increases the rate of reduction of the lift with respect to the increase in the flow rate, and the lift at the working flow rate Q1 decreases. However, even if the auxiliary blade 20 is provided, the deadline lift hardly changes. Further, the efficiency η ₁ , η ₂ is hardly changed by providing the auxiliary blade 20. Furthermore, the suction suction lifts N ₁ and N ₂ are hardly changed due to the provision of the auxiliary blades 20. By providing the auxiliary blade 20 in this way, the lift at the working flow rate can be adjusted without changing the cutoff lift, efficiency, and suction performance. Further, there is no need to perform processing such as cutting of the blade 16 for performance adjustment. Furthermore, since there is no need to provide a control valve in the discharge side pipe line, loss can be suppressed.

  FIG. 7 shows measurement results obtained by actually measuring the lift, efficiency, suction actual lift, and shaft power by using the auxiliary blades 20 having different blade lengths α1. In FIG. 7, “●” indicates that the blade length α1 of the auxiliary wing 20 is 6 mm (α1 = 6 mm), and “▲” indicates that the blade length α1 of the auxiliary wing 20 is 17 mm (α1 = 17 mm). “” Indicates the case where the blade length α1 of the auxiliary blade 20 is 47 mm (α1 = 47 mm).

Comparing the lift curve H, the longer the blade length α1 of the auxiliary blade 20, the higher the reduction rate of the lift with respect to the flow rate increase. Further, even if the blade length α1 changes, the deadline lift hardly changes. Next, when the efficiency η is compared, even if the blade length α1 of the auxiliary blade 20 is changed, the maximum efficiency (flow rate 12 m ³ / min) changes only about 1%, and the blade length α1 also in the flow rate region other than the highest efficiency point. The change in efficiency due to the difference is not great. Regarding the actual suction head N and the shaft power P, the change in characteristics due to the difference in the blade length α1 is extremely small. Thus, from the actual measurement results, the lift at the working flow rate can be adjusted without changing the suction lift by changing the blade length α1 of the auxiliary blade 20, and at that time, the efficiency, the suction performance, and the shaft It can be confirmed that the change in power is small.

(Second Embodiment)
The second embodiment of the present invention shown in FIGS. 8 to 10 is an example in which the present invention is applied to the impeller 2 of the horizontal suction single suction centrifugal pump 31. In addition, as an adjustment mechanism for adjusting the angular position around the rotation center L of the auxiliary wing 57, a frame body 56A, 56B, a bolt 58, and a nut 59 described later are provided.

  Referring to FIG. 8, a centrifugal impeller (hereinafter simply referred to as “impeller”) 36 is disposed in a spiral chamber 35 formed by the casing 32 and the suction cover 34. The impeller 36 is fixed to a main shaft 37 extending in the horizontal direction in the figure. The main shaft 37 extends through the casing 32. Bearings 39A and 39B are arranged on the frame 38 fixed to the casing 32, and the right side of the main shaft 37 is rotatably supported by these bearings 39A and 39B. A mechanical seal 40 is disposed at a portion where the main shaft 37 penetrates the casing 32. In FIG. 8, the right end is connected to a prime mover (not shown).

  When the main shaft 37 is rotationally driven by the prime mover, the impeller 36 rotates in the spiral chamber 35. The water that flows into the spiral chamber 35 from the suction port 41 flows into the rotating impeller 36 from the impeller inlet 42, and is discharged from the impeller outlet 43 through the discharge port 44.

  Referring to FIGS. 9 and 10 together, the impeller 36 includes a boss portion 51 fixed to the main shaft 37 and a main plate (side wall plate) 52 extending from the boss portion 51 in the radial direction of the main shaft 37. To the main plate 52, the base end sides of a plurality of single suction type blades 53 are fixed. The tip ends of the plurality of blades 53 are connected to a side plate (side wall plate) 54. The outer periphery 52a of the main plate 52 is circular. Further, the side plate 54 has a circular outer periphery 54 a, and a central opening constitutes the impeller inlet 42. Further, the portion sandwiched between the outer peripheries 52 a and 54 a of the main plate 52 and the side plate 54 constitutes the impeller outlet 43. The main plate 52 and the side plate 54 are arranged coaxially with the main shaft 37, and the rotation center L of the main shaft is also the rotation center of the main plate 52 and the side plate 54. As shown in FIG. 9, the blades 53 are arranged in a cascade with respect to the side plate 54, the inlet 53 a is located at the impeller inlet 42, and the outlet 53 b is located at the impeller outlet 43.

  As shown in FIGS. 9 and 10, the circular outer peripheries 52a and 54a of the main plate 52 and the side plate 54 have a pair of frames 56A and 56B that are semicircular when viewed from the direction of the main shaft 37 (direction of the rotation center L). Is attached. These frame bodies 56A and 56B are provided with auxiliary wings 57 at positions corresponding to the individual blades 53. Therefore, the auxiliary wings 57 are separate from the blades 53, the main plate 52, and the side plates 54. Specifically, each of the frames 56A and 56B includes a first semi-annular portion 56a disposed outside the main plate 52 and a second semi-annular portion 56b disposed outside the side plate 54. The vicinity of the outer peripheries 52a and 54a of the main plate 52 and the side plate 54 is closely fitted between the semi-annular portions 56a and 56b. The left and right ends of the auxiliary wing 57 in FIGS. 8 and 10 are connected to the semi-annular portions 56a and 56b. The cross-sectional shape of the auxiliary wing 57 in the cross section orthogonal to the rotation center L is the same as that of the auxiliary wing 20 of the first embodiment (see FIG. 4).

  The pair of frames 56A and 56B includes a flange portion 56c. The outer periphery 52a, 54a of the main plate 52 and the side plate 54 is fastened to the impeller 36 by a flange portion 56c with bolts 58 and nuts 59 (see FIG. 9) as fastening means. Therefore, if the bolts 58 and nuts 59 are loosened, the frames 56A and 56B are rotated along the outer peripheries 52a and 54a of the main plate 52 and the side plate 54 as shown by arrows A1 and A2 in FIG. The surrounding angular position can be adjusted. Since the auxiliary wings 57 are provided on the frame bodies 56A and 56B, the blade length α1 and the protrusion amount α2 can be adjusted by rotating the frame bodies 56A and 56B. If the frame bodies 56A and 56B are tightened again with the bolts 58 and nuts 59 after adjusting the angular positions of the frame bodies 56A and 56B, the angular position of the auxiliary wings 57 can be fixed.

  For example, when the auxiliary wing 57 is at the angular position shown in FIG. 9 and the frames 56A and 56B are rotated in the direction indicated by the arrow A1, the blade length α1 of the auxiliary wing 57 becomes longer. As a result, the rate of reduction of the lift with respect to the increase in the flow rate increases and the lift at the working flow rate decreases, but the deadline lift hardly changes. Also, the efficiency, the actual suction head, and the shaft power hardly change. On the other hand, when the frames 56A and 56B are rotated in the direction indicated by the arrow A2, the blade length α1 of the auxiliary blade 57 is shortened. As a result, the rate of decrease in the lift with respect to the increase in the flow rate becomes small, and the lift at the working flow rate increases, but the deadline lift hardly changes. Also, the efficiency, the actual suction head, and the shaft power hardly change.

  As described above, in the single suction centrifugal pump 31 of the present embodiment, the head length can be easily changed by changing the blade length α1 of the auxiliary wing 57 simply by adjusting the angular position of the frame bodies 56A and 56B around the rotation center L. Can be adjusted. Further, the auxiliary wings 57 can be eliminated from the impeller 36 by removing the frames 56A and 56B. On the contrary, the performance adjustment by the auxiliary wings 57 can be realized simply by attaching the frame bodies 56A and 56B to the existing impeller. In addition, the structure of this embodiment is applicable also to the double suction type centrifugal pump like 1st Embodiment. Conversely, the detachable auxiliary blade 20 as in the first embodiment can also be applied to a double suction centrifugal pump as in this embodiment.

  Other configurations and operations of the second embodiment are the same as those of the first embodiment.

(Third embodiment)
The third embodiment of the present invention shown in FIGS. 11 and 12 is a single suction centrifugal pump similar to the second embodiment, but the adjustment mechanism for adjusting the angular position around the rotation center L of the auxiliary blade 62 is different. In the figure, the same elements as those of the second embodiment are denoted by the same reference numerals.

  The adjusting mechanism of the auxiliary wing 62 in this embodiment includes an auxiliary wing holding cylinder (auxiliary wing holding member) 63, a moving means 64 schematically shown only in FIG.

  The auxiliary blade holding cylinder 63 has a cylindrical shape with openings at both ends, and is disposed so as to cover the outer periphery of the impeller 36. Specifically, the auxiliary blade holding cylinder 63 is a first cylindrical portion 63 a that surrounds the outer peripheries 52 a and 54 of the main plate 52 and the side plate 54 of the impeller 36, and a second cylindrical shape that surrounds the boss portion 51 of the impeller 36. A portion 63b, and a disc-like portion 63c that connects the first tubular portion 63a and the second tubular portion 63b. Further, the auxiliary wing holding cylinder 63 can be moved back and forth in the direction along the rotation center L with respect to the impeller 36 as indicated by arrows B1 and B2, and the impeller 36 is provided with the impeller 36 as indicated by arrows C1 and C2. On the other hand, it can rotate around the rotation stop.

  The outer surfaces 52a and 54a of the main plate 52 and the side plate 54 are in contact with the inner surface of the first cylindrical portion 63a. Further, auxiliary wings 62 are provided at positions corresponding to the blades 53 in the first cylindrical portion 63a. The cross-sectional shape of the auxiliary wing 57 in the cross section orthogonal to the rotation center L is the same as that of the auxiliary wing 20 of the first embodiment (see FIG. 4). A gap 66 communicating with the impeller outlet 43 is formed between one auxiliary wing 62 and another auxiliary wing 62 adjacent thereto.

  The cam mechanism 65 includes a cam groove 68 formed in the second cylindrical portion 63 b of the auxiliary blade holding cylinder 63 and a cam 69 on the boss portion 51 side disposed in the cam groove 68. As clearly shown in FIG. 12, the cam groove 68 extends at an angle with respect to the rotation center L. The cam 69 includes a pin 70 fixed to the second cylindrical portion 63 b and a sliding piece 71 attached to the tip of the pin 70.

  The moving means 64 only needs to be capable of moving the auxiliary blade holding cylinder 63 forward and backward in the direction along the rotation center L and positioning the auxiliary blade holding cylinder 63 in the direction along the rotation center L. Examples of such moving means 64 include a hydraulic cylinder that moves the auxiliary wing holding cylinder 63 forward and backward, and a screw mechanism that manually moves the auxiliary wing holding cylinder 63 forward and backward.

  FIG. 13A shows a state in which the auxiliary blade holding cylinder 63 is at the rightmost position (most retracted position) in the drawing with respect to the impeller 36. In this state, the cam 69 is in contact with the tip of the cam groove 68. Referring also to FIG. 13B, when the auxiliary wing holding cylinder 63 is at the highest retracted position, the blade length α1 of the auxiliary wing 62 is the longest (the protrusion amount α2 is the largest). When the auxiliary wing holding cylinder 63 is moved forward from the last retracted position as indicated by arrow B1, the auxiliary wing holding cylinder 63 is moved by the engagement of the cam groove 68 and the cam 69 to the arrow C1. Rotate in the direction indicated by. As the arrow C1 rotates, the blade length α1 of the auxiliary blade 62 decreases.

  14A and 14B show a state where the auxiliary blade holding cylinder 63 has reached the leftmost position (the most advanced position) with respect to the impeller 36 in the drawing. At the most advanced position, the blade length α1 of the auxiliary blade 62 is the longest (the protrusion amount α2 is the largest). When the auxiliary blade holding cylinder 63 is moved to the right in the drawing as the moving means 64 is indicated by the arrow B2, the auxiliary blade holding cylinder 63 is moved to the arrow C2 by the engagement of the cam groove 68 and the cam 69. Rotate in the direction indicated by. As the arrow C2 rotates, the blade length α1 of the auxiliary blade 62 increases.

  In the single suction centrifugal pump of the present embodiment, the blade length α1 of the auxiliary blade 62 can be changed steplessly by moving the auxiliary blade holding cylinder 63 in the direction along the rotation center L by the moving means 64. .

  Other configurations and operations of the third embodiment are the same as those of the second embodiment.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, the auxiliary wing may be integrated with the blade. Although the present invention has been described by taking a centrifugal pump as an example, the present invention can be applied to various fluid machines such as a centrifugal compressor and a water turbine including a pump reversing turbine.

Sectional drawing which shows the double suction type centrifugal pump provided with the centrifugal impeller which concerns on 1st Embodiment of this invention. Sectional drawing in the II-II line of FIG. The elements on larger scale of FIG. 1 which show a centrifugal impeller. FIG. 3 is a schematic partial enlarged view of FIG. 2. The figure which shows the speed triangle of an impeller exit. The conceptual performance curve of the double suction type centrifugal pump of 1st Embodiment. The performance curve of the double suction type centrifugal pump of 1st Embodiment. Sectional drawing which shows the single suction type centrifugal pump provided with the centrifugal impeller which concerns on 2nd Embodiment of this invention. Sectional drawing in the IX-IX line of FIG. The elements on larger scale of FIG. 8 which show a centrifugal impeller. The fragmentary sectional view which shows the centrifugal impeller which concerns on 3rd Embodiment of this invention. The arrow view in the XII-XII line | wire of FIG. The partial top view of a centrifugal impeller when an auxiliary blade exists in the most protruding position. The fragmentary sectional view which shows an auxiliary wing when it exists in the most protruding position. The partial top view of a centrifugal impeller when an auxiliary blade exists in the most retracted position. The fragmentary sectional view which shows the auxiliary wing in the most retracted position. The diagram for demonstrating an example of the performance adjustment method of the conventional centrifugal impeller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double suction type centrifugal pump 2 Centrifugal impeller 3 Casing 3A Upper casing 3B Lower casing 4 Spiral chamber 5 Spindle 6A, 6B Bearing bracket 7A, 7B Bearing 8A, 8B Mechanical seal 9 Suction inlet 10A, 10B Impeller inlet 11 Impeller Outlet 12 Discharge port 15 Boss part 16 Main plate 17 Blade 17a Inlet 17b Outlet 17c Inner surface 17d Outer surface 18A, 18B Side plate 18a Outer periphery 20 Auxiliary blade 20a Base end surface 20b Tip end surface 20c Outer side surface 20d Inner side surface 23 Bolt 31 Single suction casing centrifugal pump 32 34 Suction cover 35 Swirl chamber 36 Centrifugal impeller 37 Main shaft 38 Frame 39A, 39B Bearing 40 Mechanical seal 41 Suction port 42 Impeller inlet 43 Impeller outlet 44 Discharge port 51 Boss portion 52 Main plate 52a Outer periphery 53 Blade 53a Inlet 5 3b outlet 54 side plate 54a outer periphery 56A, 56B frame 56a, 56b semi-annular part 56c flange part 57 auxiliary wing 58 bolt 59 nut 62 auxiliary wing 63 auxiliary wing holding cylinder 63a, 63b cylindrical part 63c disk-like part 64 moving means 65 Cam mechanism 66 Clearance 68 Cam groove 69 Cam 70 Pin 71 Sliding piece L Center of rotation R Direction of rotation

Claims (8)

A plurality of blades disposed in a blade row on the side wall plate, the inlet is positioned on the rotation center side of the side wall plate, and the outlet is positioned on the outer peripheral side of the side wall plate;
A centrifugal impeller comprising a plurality of auxiliary blades extending along the outer periphery of the side wall plate from the corresponding outlet of the blade toward the opposite side of the rotation direction of the side wall plate.   The centrifugal impeller according to claim 1, wherein an exit angle of the blade and a blade angle of the auxiliary blade are different.   The centrifugal impeller according to claim 2, wherein the auxiliary wing is separate from the blade and is detachably fixed to the side wall plate. The auxiliary wing is separate from the blade,
The centrifugal impeller according to claim 2, further comprising an adjustment mechanism that adjusts an angular position of the auxiliary wing around the rotation center of the side wall plate. The adjusting mechanism is
A pair of frames provided with the auxiliary wings and attached to the outer periphery of the side wall plate;
The centrifugal impeller according to claim 4, further comprising: a tightening unit that releasably fastens the pair of frames to the outer periphery of the side wall plate. The adjusting mechanism is
The auxiliary wing is provided, and is attached to the side wall plate so as to be able to advance and retreat in a direction along the rotation center of the side wall plate with respect to the side wall plate and to be rotatable about the rotation center of the side wall plate with respect to the side wall plate. An auxiliary wing holding member,
Moving means for advancing and retracting the auxiliary wing holding member in a direction along the rotation center of the side wall plate, and positioning;
The centrifugal impeller according to claim 4, further comprising: a cam mechanism that changes an angular position of the auxiliary blade holding member around the rotation center in accordance with a position in a direction along the rotation center. A fluid machine comprising the centrifugal impeller according to any one of claims 1 to 6. A centrifugal pump comprising the centrifugal impeller according to any one of claims 1 to 6.

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