JP4882939B2 - Movable blade axial flow pump - Google Patents

Description

  The present invention relates to an axial flow type pump, and more particularly to a movable blade axial flow pump.

  An example of a conventional movable blade axial flow pump is described in Patent Document 1. In the pump described in this publication, as shown in FIG. 1, the impeller hub is fitted to the impeller hub, and the impeller blade is configured to be rotatable about the centerline of the impeller shaft. Yes. The inner diameter side of the flow path, which is the hub side of the impeller blade, is integrated with a spherically formed member, and the blade portion is partially cut in the outer diameter direction at a portion protruding from the member. . On the other hand, on the flow path outer diameter side, which is the tip side of the impeller blade, the pump casing and the suction casing are formed in a spherical shape, and the tip of the impeller blade is formed in a spherical shape or a cross section so as to form a slight gap with these casings. It is formed in a circular shape to enable smooth rotation of the impeller blades.

  Another example of a conventional movable blade axial flow pump is described in Patent Document 2. In the pump described in this publication, similarly to Patent Document 1, the inner diameter side of the impeller is integrated with a spherically formed base material. However, unlike the impeller blade described in Patent Document 1, the portion protruding from the base material has a circular cross section, and the impeller hub into which the base material is fitted is formed in a spherical shape. A slight gap is formed between the impeller and the impeller hub to enable smooth rotation of the impeller. In any of these pumps, since the impeller blades or impellers are rotated, efficient pump operation is possible from a small water amount region to a large water amount region.

Japanese Patent Laid-Open No. 7-238899 JP 58-197499 A

  In the impeller blades and impellers described in Patent Documents 1 and 2, the hub surface and the tip surface are formed concentrically with the hub and the casing, so that the impeller blades and the impeller can be rotated about the axis thereof. . However, on the hub side, which is formed on a spherical surface having a larger curvature than the tip side, when the impeller blades or the impeller flow through, the flow may be separated from the hub surface.

  When the flow is separated from the blade surface, the loss on the hub side of the impeller blade or impeller increases compared to the fixed blade axial flow pump in which the hub surface and the tip surface are straight in the axial cross section, and the movable blade axial flow pump Cause performance degradation. As described above, in the conventional movable blade axial flow pump, the stable operation range is increased while allowing a decrease in pump efficiency.

  The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to improve pump efficiency and increase a stable operation range in a movable blade axial flow pump. Another object of the present invention is to suppress flow separation in the movable blade without impairing the mobility of the movable blade. Moreover, it is in reducing the loss in a movable blade part and reducing the energy consumption of a movable blade pump. And it aims at achieving at least one of these objectives.

  A feature of the present invention that achieves the above object is that a plurality of impeller blades provided at intervals on the outer peripheral side of the impeller hub are movable around a blade rotation axis set for each blade. In the blade axial flow pump, the inner diameter end shape of the impeller blade is an arc shape, and the meridional shape of the outer peripheral surface of the impeller hub is the same as the central position of the inner diameter end arc of the impeller blade. The surface shape is a curved shape having a smaller curvature than the curvature of the arc when the arc is formed.

  Another feature of the present invention that achieves the above object is that a plurality of impeller blades provided at intervals on the outer peripheral side of the impeller hub can be rotated around a blade rotation axis set for each blade. In a movable vane axial flow pump, a guide vane hub having a plurality of guide vanes arranged at intervals in the circumferential direction is arranged on the downstream side of the impeller hub, and the guide vane hub outside the portion where the guide vanes are located is arranged. The diameter is larger than the minimum outer diameter of the impeller hub and smaller than the maximum outer diameter of the impeller hub.

  In these features, the outer diameter of the impeller hub is preferably smaller at the upstream end than the downstream end, and the outer diameter of the guide vane mounting portion of the guide vane hub is larger than the outer diameter of the downstream end of the impeller hub. Larger is preferred. Also, the outer diameter of the guide vane hub should be gradually increased in the flow direction from the outer diameter of the downstream end of the impeller hub to provide a contracted flow area, and the guide vane hub has a substantially cylindrical shape to which the outer diameter end of the guide vane is attached. It has a casing, and it is good to make the meridian cross-sectional shape of the internal peripheral surface facing the impeller blade of this casing, and the shape of the outer-diameter end of an impeller blade into a concentric shape.

  According to the present invention, in the movable blade axial flow pump, the outer curvature of the hub located on the inner diameter side is made larger than the curvature on the hub side of the blade, so that separation of the flow on the hub side from the blade surface can be suppressed, The pump efficiency can be improved and the stable operating range can be increased. Further, it is possible to suppress the separation of the flow in the movable blade without impairing the mobility of the movable blade. Furthermore, since the loss in the movable blade portion is reduced, the energy consumption of the movable blade pump is also reduced.

  Hereinafter, several embodiments of the movable blade axial flow pump according to the present invention will be described with reference to the drawings. FIG. 1 is a meridional sectional view of an embodiment of a movable blade axial flow pump 100. A cylindrical inner cylinder portion 11 is accommodated in a cylindrical casing 10. The inner cylinder part 11 is held in the casing 10 by the guide vanes 3.

  The inner cylinder part 11 has a blunt-shaped front cover 12 at the upstream end of the flow. An impeller hub 2 is disposed downstream of the front cover 12 in the axial direction, and a cylindrical portion 4a having a constant outer diameter and a gradual decrease in the outer diameter are provided on the downstream side of the impeller hub 2 in the axial direction. A guide vane hub 4 having a ball portion 4b is arranged. The guide blade 3 has an inner diameter side fixed to the outer surface of the cylindrical portion 4 a and an outer diameter side fixed to the inner wall of the casing 10. There are a plurality of guide blades 3, for example, three, and they are arranged at substantially equal pitches in the circumferential direction.

  The impeller hub 2 is rotatable in the inner cylinder portion 11, and the main shaft 5 connected to the impeller hub 2 protrudes from the rear end of the guide vane hub 4. Although not shown, the main shaft 5 is connected to a motor that is a prime mover for driving the impeller hub 2. Impeller blades 1 are attached to the outer peripheral side of the impeller hub 2 at a plurality of locations in the circumferential direction. The impeller blade 1 is rotatable in a direction perpendicular to the axial direction of the inner cylinder portion 11, that is, around a radial axis (blade turning shaft) 6 of the axial flow pump 100.

  The outer diameter of the impeller hub 2 in the meridional section of the movable blade axial flow pump 100 is an arc, and the radius of the arc is R5. The center of the arc of R5 is on the blade rotation shaft 6 and extends to the opposite side of the impeller blade 1 from the intersection with the central shaft 13 of the axial flow pump 100. The impeller hub 2 has an outer diameter at the upstream end substantially the same as the outer diameter of the rear end of the front cover 12, and the outer diameter at the downstream end of the impeller hub 2 is equal to that of the guide vane hub 4. It is almost the same as the outer diameter of the front end. Therefore, the impeller hub 2 has a shape in which the blade rotation shaft 6 part protrudes most into the flow path.

  In the impeller blade 1 attached to the impeller hub 2, the rotating shaft 14 that rotates the impeller blade 1 is slightly exposed to the flow path on the inner diameter end side that is the impeller hub 2 side. The inner diameter side end of the impeller blade 1 is located on the outer diameter side of the exposed portion of the rotating shaft 14. Here, the inner diameter side end of the impeller blade 1 also has an arc shape with a radius R <b> 6, and has its center on the blade rotation shaft 6. The arc diameter R6 of the inner diameter end of the impeller blade 1 is larger than the outer peripheral radius R5 of the impeller hub 2.

  The outer diameter side end of the impeller blade 1 is also formed in an arc shape, and the center of the arc is the intersection of the blade swirl shaft 6 and the central axis of the axial flow pump 100. The radius of this arc is R4. The casing 10 is a circular arc having a radius R3 centering on the intersection of the blade swirl shaft 6 and the central shaft 13 of the axial flow pump 100, and has an inner peripheral surface cut. Here, the arc diameter R4 of the outer diameter end of the impeller blade 1 is slightly smaller than the radius R5 of the inner circumference forming arc of the casing 10. The axial length of the impeller blade 1 is longer on the inner diameter end side than on the outer diameter end side, and the impeller blade 1 has a pseudo trapezoidal meridian shape.

  In the axial flow pump 100 of the present embodiment configured as described above, the curvature R6 of the inner diameter end of the impeller blade 1 is set as the impeller hub 1 so that the impeller blade 1 can be rotated around the blade rotation shaft 6. 2 is larger than the curvature R5 of the outer diameter surface of the impeller blade 2. Therefore, the flow 8 can be controlled at the rear portion or the rear portion of the impeller blade 1 to prevent separation without following the outer peripheral surface shape of the cylindrical portion 11. . Accordingly, it is possible to avoid the formation of a region where the impeller blade 1 was not performing sufficient work due to the separation of the flow on the inner diameter side (hub side) of the outlet of the impeller blade 1. Due to this improvement in the flow, the impeller blade 1 performs sufficient work in the entire region from the upstream side (inlet) to the downstream side (outlet) of the impeller blade 1.

  That is, according to the present embodiment, energy can be given to water more efficiently, and the efficiency of the axial flow pump is improved. Further, the separation generated on the downstream side of the impeller blade 1 may disturb the flow and adversely affect the guide blade 3. However, since the disturbance of the flow is prevented, this adverse effect can be prevented. Furthermore, the loss on the hub side of the guide vane 3 is also reduced. Thereby, the energy consumption of the movable blade axial flow pump 100 can be reduced.

  In the above embodiment, the root side of the impeller blade 1 and the outer periphery of the impeller hub 2 are both formed in an arc shape, and the center of R on the root side of the impeller blade 1 and the outer periphery of the impeller hub 2 are formed. The center position of R is changed. However, the outer peripheral shape of the impeller hub is not limited to this, and may be a spherical surface or an elliptical spherical surface having a smaller curvature than R on the root side of the impeller blade 1, or a free curved surface approximating these spherical surfaces.

  However, in the case of the above-described free-form surface, in order to maintain the mobility of the impeller blade 2 that is a function as a movable blade axial flow pump, the curvature of the root side of the impeller blade 1 is set to the opposite impeller hub. Must be greater than 2 curvature. The flow passing through the impeller blade 1 flows without being along the outer peripheral surface of the impeller hub 2 on the hub side, and the flow 7 in the separated area is defined as a flow along the outer peripheral surface of the impeller hub 2. Is possible.

  Thereby, the flow on the outlet side of the impeller blade 1 and on the hub side is improved, and the rotational power of the impeller is efficiently applied to the water that is the working fluid in the entire region from the inlet to the outlet of the impeller blade 1. Thus, the efficiency of the movable blade axial flow pump is improved. Furthermore, in the past, turbulence 7 may have occurred due to separation in the flow that has passed through the impeller blade 1, but since this turbulence 7 can be prevented or reduced, the guide blade 3 disposed on the downstream side of the impeller blade 1. It is possible to avoid the influence of the disturbance 7. Therefore, the loss on the hub side of the guide vane 3 is also reduced, and the energy consumption of the movable blade axial flow pump is reduced.

  In the above embodiment, the tip side of the impeller blade 1 is processed with an arc of R4, and the inner peripheral surface of the casing 10 is also processed with an arc of R3. However, similar to the hub side, it may be a free curved surface with a small curvature. When the shape of the impeller blade 1 on the tip side is changed from a concentric spherical surface to a free curved surface having a small curvature, the flow passing through the impeller blade 1 can be made closer to a straight line on the tip side than before. When the impeller blade 1 is rotated around the pivot axis 6 to change the direction, the tip of the impeller blade 1 is not a concentric spherical surface. The gap between the peripheral surfaces changes.

  When the gap on the tip side of the impeller blade 1 is widened, the leakage flow increases. For this reason, the efficiency of the movable blade axial flow pump may be reduced more than the reduction in loss obtained by reducing the curvature. The position of the tip of the impeller blade 1 is the maximum outer diameter position of the impeller blade 1, and is the position where the circumferential speed when the main shaft 5 is rotated becomes maximum. Since the peripheral speed is maximized at the tip position, the pressure difference between the pressure surface and the suction surface, which are the two surfaces of the impeller blade 1, is also at or near the tip position.

  Therefore, the influence on the efficiency of the movable blade axial flow pump is greater than the leakage flow on the hub side of the impeller blade 1. Therefore, when a free curved surface having a large curvature is adopted for the hub surface of the impeller blade 1, the curvature of the inner peripheral surface of the impeller blade 1 and the casing 10 is taken into consideration in consideration of an increase in loss due to leakage flow in the gap. Etc.

  Another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a meridional cross-sectional view of the movable blade axial flow pump. This embodiment is different from the above embodiment in that the shape of the impeller blade 1 on the hub side and the shape of the outer peripheral surface of the impeller hub 2 are concentric spherical surfaces. The outer periphery of the impeller hub 2 is formed by an arc surface of R1 in the axial direction, and the hub surface of the impeller blade 1 is formed by an arc surface of R2. The impeller blade 1 can rotate around the blade rotation axis 6.

  In this embodiment, in addition to the above features, the outer peripheral diameter of the impeller hub 2 is D1 on the upstream side and D3 on the downstream side of the position where the impeller blades 1 are disposed. The diameter D3 is larger than the diameter D1. According to this embodiment, as in the above embodiment, the flow that has passed through the impeller blades 1 flows along the outer peripheral surface of the impeller hub 2 even on the hub side, and flow loss due to separation can be avoided. Thereby, the energy consumption of a movable blade axial flow pump can be reduced.

  Still another embodiment of the movable blade axial flow pump according to the present invention will be described with reference to FIGS. These drawings are meridional cross-sectional views of the movable blade axial flow pump. It is suitable for a pump that operates in a wider range from a small water volume range to a large flow rate range.

  In order to widen the operating range using the pumps shown in the above embodiments, it is necessary to make the impeller blade 1 swivel about the blade swivel shaft 6. At that time, unless the gap between the hub surface of the impeller blade 1 and the outer peripheral surface of the impeller hub 2 is increased, the hub of the impeller blade 1 interferes with the impeller hub 2. As a result, although not as much as the tip side of the impeller blade 1, even on the hub side of the impeller blade 1, when the gap increases, the leakage flow increases and the loss of the movable blade axial flow pump increases.

  In order to solve this problem, in this embodiment, the shape of the impeller blade 1 is reduced in the leakage flow in the gap on the hub side. Specifically, the shape of the hub side of the impeller blade 1 is an arc shape with a radius R2, the corresponding meridional cross-sectional shape of the outer periphery of the impeller hub 2 is an arc shape with a radius R1 (R1 <R2), and the radius R1 The center of the arc of R2 is the same position on the central axis of the main shaft 5. As a matter of course, the impeller blade 1 can be rotated around the blade rotation axis 6.

  A plurality of guide vanes 3 are arranged at a substantially equal pitch in the circumferential direction downstream of the impeller blade 1. The hub diameter of the guide blade 3 or the outer diameter of the guide blade hub 4 is larger than the minimum diameter of the portion where the impeller hub 2 faces the impeller blade 1. That is, the outer diameter of the impeller hub 2 disposed on the center line side of the movable blade axial flow pump gradually increases in the flow direction from the diameter D1 on the upstream side of the impeller blade 2, and reaches the maximum at the blade swirl shaft 6 portion. The diameter becomes 2 * R1, and then gradually decreases to the minimum diameter D2. The outer diameter of the guide vane hub 4 is slightly larger than D2 or D2, and the diameter of the portion facing the guide vane 3 is smaller than 2 * R1.

  In the embodiment shown in FIG. 3, the outer diameter of the guide vane hub 4 is a cylindrical shape having a diameter slightly larger than the minimum diameter D <b> 2 of the impeller hub 2 on the upstream side of the flow, and a portion past the guide vane 3. The diameter gradually decreases from. On the other hand, in the embodiment shown in FIG. 4, the outer diameter of the guide vane hub 4 gradually increases from substantially the same outer diameter as the downstream diameter D2 of the impeller hub 2, and the guide vane 3 has a cylindrical shape with the same diameter. Yes, after passing through the guide vane 3, the outer diameter of the guide vane hub 4 gradually decreases as in the embodiment shown in FIG.

  If the outer diameter of the guide vane hub 4 is configured in this way, in the case of the embodiment of FIG. 3, the flow passing through the impeller blades 1 is separated on the hub side, and the region where the flow is disturbed can be reduced. . Therefore, it is possible to avoid the disturbance of the flow caused by the separation generated on the hub side on the outlet side of the impeller blade 1 from reaching the guide blade 3, and to reduce the loss on the hub side of the guide blade 3. Therefore, energy consumption of the movable blade axial flow pump can be reduced.

  Further, in the embodiment shown in FIG. 4, in order to further reduce the energy consumption in the region where water flows from the impeller blade 1 to the guide blade 3, the shape of the guide blade 3 provided on the hub side downstream of the impeller is changed. As the shape, a contracted flow rate region is provided. It is possible to further reduce the flow turbulence region due to the separation generated on the hub side on the outlet side of the impeller blade 1. At the same time, the turbulence of the flow caused by the separation generated on the hub side on the outlet side of the impeller blade 1 is rectified, and the turbulence of the flow on the guide blade 3 can be avoided.

  An example in which the impeller blade 1 and the impeller hub 2 in the embodiment shown in FIG. 1 are combined with the guide vane 3 and the guide vane hub 4 shown in FIG. Shown in cross section. The hub surface of the impeller blade 1 has an arc shape with a radius R5, and the meridional shape of the outer diameter of the impeller hub 2 has an arc shape with a radius R6. And the center of the circle of radius R5 and the circle of radius R6 is not the same position. The hub shape of the impeller blade 1 may be an elliptical shape or a free curved surface similar to the circular shape in addition to the circular arc.

  The outer diameter on the inlet side of the guide vane hub 4 is substantially the same as the outer diameter D2 on the outlet side of the impeller hub 2, and a shape in which a contracted flow rate region that gradually increases in the direction of water flow is formed. As in the embodiment shown in FIG. 3, the outer diameter of the guide vane hub 4 is set to an almost constant outer diameter on the inlet side, and this constant diameter is made smaller than the maximum outer diameter 2 * R1 of the impeller hub 2. May be.

  According to the present embodiment, it is possible to reduce the region where the flow passing through the impeller blades 1 does not follow the outer peripheral surface shape of the impeller hub 2 on the hub side and is separated from the outer diameter side, and the blades. The turbulence of the flow passing through the vehicle blade 1 can be rectified, and the turbulence of the flow up to the guide vanes can be avoided. Therefore, energy consumption of the movable blade axial flow pump can be suppressed.

The meridian surface shape figure of one Example of the movable blade axial flow pump which concerns on this invention. The meridian surface shape figure of the other Example of the movable blade axial flow pump which concerns on this invention. The meridian surface shape figure of the further another Example of the movable blade axial flow pump which concerns on this invention. Fig. 4 is a meridional shape of the movable blade axial flow pump shown in Fig. 3. The meridian surface shape figure of the further another Example of the movable blade axial flow pump which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Impeller blade, 2 ... Impeller hub, 3 ... Guide blade, 4 ... Guide blade hub, 5 ... Main shaft, 6 ... Blade rotation shaft, 7, 8 ... Flow on impeller exit side, 10 ... Casing, R1 ... Arc diameter representing the meridian surface of the impeller hub, R2 ... arc diameter representing the hub shape of the impeller blade, R3 ... arc diameter representing the inner periphery of the impeller casing, R4 ... representing the tip of the impeller blade Arc diameter, R5: Arc diameter representing the impeller hub meridian surface, R6: Arc diameter representing the hub shape of the impeller blade, D1: Cylindrical diameter upstream of the impeller hub, D2: Downstream side of the impeller hub The cylindrical diameter of D3, ... the downstream cylindrical diameter of the impeller hub.

Claims (6)

  In a movable vane axial flow pump in which a plurality of impeller blades provided at intervals on the outer peripheral side of the impeller hub are rotatable around a blade swirl axis set for each blade, When the inner diameter end shape is an arc shape, and the meridional shape of the outer peripheral surface of the impeller hub is the same center position as the center position of the inner diameter end arc of the impeller blade, the meridional shape of the impeller hub is formed by an arc. A movable blade axial flow pump characterized by having a curved shape with a curvature smaller than the curvature of the arc.   In the movable blade axial flow pump in which a plurality of impeller blades provided at intervals on the outer peripheral side of the impeller hub are rotatable around a blade swirl axis set for each blade, the impeller hub includes: A guide vane hub having a plurality of guide vanes arranged at intervals in the circumferential direction on the downstream side is arranged, and the outer diameter of the guide vane hub at the portion where the guide vanes are located is the smallest outside of the impeller hub. A movable blade axial flow pump characterized in that it is larger than the diameter and smaller than the maximum outer diameter of the impeller hub.   The movable blade axial flow pump according to claim 1 or 2, wherein the outer diameter of the impeller hub is smaller at the upstream end than at the downstream end.   The movable blade axial flow pump according to claim 1 or 2, wherein an outer diameter of a guide blade mounting portion of the guide blade hub is larger than an outer diameter of a downstream end of the impeller hub.   5. The movable blade axial flow pump according to claim 4, wherein an outer diameter of the guide blade hub is gradually increased in a flow direction from an outer diameter of a downstream end of the impeller hub to provide a contracted flow rate region.   It has a substantially cylindrical casing to which the outer diameter end of the guide vane is attached, and the meridional cross-sectional shape of the inner peripheral surface of the casing facing the impeller blade and the outer diameter end of the impeller blade are concentric. The movable blade axial flow pump according to claim 1 or 2, wherein

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