JP6924121B2 - Impeller - Google Patents

Description

The present invention relates to an impeller used for a centrifugal blower or the like, and relates to an impeller that causes a fluid that has flowed in along the axial direction to flow out in the radial direction.

In the impeller used for a centrifugal blower or the like, in order to efficiently send a fluid, the blade angle on the inflow side is generally set to an angle based on the theory of velocity triangle (see Patent Document 1).
That is, as shown in FIG. 3A, the velocity triangle is the peripheral velocity vector U on the inflow side of the impeller 100, the absolute velocity vector V of the fluid on the inflow side of the impeller 100, and the circumference from the base point of the absolute velocity vector V. It is formed by the relative velocity vector W toward the origin of the velocity vector U. Then, the blade angle α on the fluid inflow side is set to an angle 10 ° to 15 ° smaller than the angle θ formed by the direction of the axial flow and the relative velocity vector W.

Japanese Unexamined Patent Publication No. 2011-132810

However, in the conventional impeller 100, since the blade angle α is determined from the usage conditions of the impeller 100 such as the rotation speed, the flow rate, and the flow velocity, the blade angle α cannot be freely determined regardless of the usage conditions of the impeller 100, and the blades. The degree of freedom in designing 101 was small.

Therefore, the present invention provides an impeller having a structure capable of efficiently feeding a fluid even if the blade angle is determined regardless of the conditions of use of the impeller.

The present invention has a central shaft portion 3 and a plurality of blades 5 formed around the central shaft portion 3, and by rotating around the axial center CL of the central shaft portion 3, the central shaft portion 3 is formed. It relates to the impeller 1 which causes the fluid flowing between the adjacent blades 5 and 5 from the direction along the axial center CL of the above to flow out toward the outward side in the radial direction. In the present invention, a flow velocity increasing body 6 for increasing the flow velocity of the fluid flowing between the blades 5 and 5 is provided at the tip portion 13 of the central shaft portion 3 on the fluid inflow side. Further, the flow velocity increasing body 6 includes an upstream side portion 6b that gradually increases the outer diameter dimension from the end portion on the upstream side of the fluid flow direction toward the downstream side in the flow direction of the fluid, and the upstream side portion 6b and the above. A columnar body located between the central shaft portion 3 and the tip portion 13 on the fluid inflow side, and having a downstream side portion 6c in which a constricted portion 14 having a diameter smaller than the maximum outer diameter of the upstream side portion 6b is formed. Is.

In the impeller according to the present invention, the flow velocity increasing body can increase the flow velocity of the fluid flowing between the blades, and the absolute velocity and the relative velocity of the fluid can be set to preferable values according to the blade angle, and the fluid can be efficiently sent. Therefore, the blade angle can be determined regardless of the impeller usage conditions, and the degree of freedom in blade design can be increased.

It is a figure which shows the impeller which concerns on embodiment of this invention, FIG. 1 (a) is a plan view of the impeller, FIG. 1 (b) is a front view of the impeller, FIG. d) is an external perspective view of the impeller viewed from diagonally above. FIG. 2A is a vertical cross-sectional view of the impeller according to the embodiment of the present invention (cross-sectional view shown by cutting along the line A1-A1 of FIG. 1A), and FIG. 2B is FIG. It is an enlarged view of the B1 part of the impeller shown in (a). FIG. 3A is a diagram showing the relationship between the blades of the conventional impeller and the velocity triangle, and FIG. 3B is a diagram showing the relationship between the blades of the impeller and the velocity triangle according to the embodiment of the present invention. .. It is a figure which shows the modification 1 of the impeller which concerns on this invention, and is the figure which shows by enlarging the flow velocity increasing body of the impeller. The efficiency of the impeller 1 according to the modified example 1 (efficiency shown by the solid line in FIG. 5) and the efficiency of the conventional impeller (impeller without the flow velocity increasing body 6) (efficiency shown by the dotted line in FIG. 5) are compared. It is a figure which shows. It is a vertical cross-sectional view which shows the modification 2 of the impeller which concerns on this invention, FIG. It is a figure which shows the state which fixed the flow velocity increasing body to a part. It is a vertical sectional view which shows the modification 3 of the impeller which concerns on this invention, FIG. 7A is a figure which shows the state which separated the flow velocity increasing body from the central axis part of the impeller, and FIG. It is a figure which shows the state which fixed the flow velocity increasing body to a part.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

1 and 2 are diagrams showing an impeller 1 according to an embodiment of the present invention. 1A is a plan view of the impeller 1, FIG. 1B is a front view of the impeller 1, FIG. 1C is a back view of the impeller 1, and FIG. 1D is a back view of the impeller 1. It is an external perspective view of the impeller 1 seen from diagonally above. 2 (a) is a vertical cross-sectional view of the impeller according to the embodiment of the present invention (cross-sectional view shown by cutting along the A1-A1 line of FIG. 1 (a)), and FIG. 2 (b) is shown. It is an enlarged view of the B1 part of the impeller shown in FIG. 2 (a).

The impeller 1 according to the present embodiment includes a cylindrical central shaft portion 3 in which a shaft hole 2 is formed, a substantially tapered blade support portion 4 integrally formed on the outer peripheral side of the central shaft portion 3, and a center. A plurality of blades 5 formed so as to straddle the outer peripheral surface 3a of the shaft portion 3 and the outer surface 4a of the blade support portion 4 and located around the central shaft portion 3 at equal intervals, and the fluid of the central shaft portion 3. It has a flow velocity increasing body 6 integrally formed at the tip portion on the inflow side. The impeller 1 having such a structure is housed in a case 7 or the like of a centrifugal blower (see FIG. 2A).

The central shaft portion 3 is formed so that the shaft hole 2 opens toward the back surface side (lower side of FIG. 2A) of the impeller 1. Further, the central shaft portion 3 is formed with a central hole 8 penetrating along the axis CL from the center of the bottom surface 2a of the shaft hole 2 to the tip surface 6a of the flow velocity increasing body 6.

The blade 5 has a thin plate shape, and is spirally formed with a constant helix angle from one end 10 side to the other end 11 side along the axial center CL of the central shaft portion 3. As shown in FIG. 1A, the twisting direction of the blade 5 is one end 10 side along the axial center CL of the central shaft portion 3 when the impeller 1 is rotated in the counterclockwise direction (counterclockwise direction). It is formed so as to be twisted in a clockwise direction (clockwise direction) toward the other end 11 side.

The blade support portion 4 connects a plurality of blades 5 and forms the bottom surface of the flow path between the adjacent blades 5 and 5, and has a wall thickness dimension similar to the wall thickness dimension of the central shaft portion 3. It is a plate-like body formed in. The outer surface 4a of the blade support portion 4 is outside the radial direction in which the fluid flowing between the adjacent blades 5 and 5 from the direction along the axial center CL of the central shaft portion 3 is orthogonal to the axial center CL of the central shaft portion 3. It has a curved surface that guides smoothly toward the direction. Between the back surface 4b of the blade support portion 4 and the outer peripheral surface 3a of the central shaft portion 3, a lightening portion 12 having a substantially triangular cross-sectional shape along the axial center CL of the central shaft portion 3 is formed. ..

The flow velocity increasing body 6 has an upstream side portion 6b that gradually increases the outer diameter dimension from the tip surface 6a (the end portion on the upstream side in the fluid flow direction) toward the downstream side in the fluid flow direction, and the upstream side portion 6b and the center thereof. It is a columnar body located between the tip portion 13 on the fluid inflow side of the shaft portion 3 and having a downstream side portion 6c in which a constricted portion 14 having a diameter smaller than the maximum outer diameter of the upstream side portion 6b is formed. .. The outer surface of the flow velocity increasing body 6 is smoothly (a sharp portion that causes a pressure loss, a pressure loss) from the tip surface 6a to the tip portion 13 of the central shaft portion 3 (the end portion on the downstream side in the flow direction of the fluid). It is formed (so that there is no stepped portion or the like that causes the above). Further, the flow velocity increasing body 6 has an external shape like a columnar body, and a central hole 8 extending from the central shaft portion 3 penetrates along the axial center CL. When the impeller 1 is housed in the case 7, the flow velocity increasing body 6 reduces the cross-sectional area of the flow path of the fluid introduction path 7a of the case 7 and narrows the flow of the fluid flowing through the fluid introduction path 7a. The flow velocity of the fluid flowing between the blades 5 and 5 of the impeller 1 is increased. Moreover, since the flow velocity increasing body 6 has a constricted portion 14 formed on the downstream side in the fluid flow direction from the maximum diameter position 15, it flows in between the blades 5 and 5 of the impeller 1 as compared with the case where there is no constricted portion 14. The flow rate of the fluid to be produced per unit time can be increased. The flow velocity increasing body 6 is smoothly connected to the tip portion 13 of the central shaft portion 3 without causing a step.

FIG. 3 shows the relationship between the blade 101 of the conventional impeller (impeller without a flow velocity increasing body) 100 and the velocity triangle (FIG. 3A), and the blade 5 of the impeller 1 and the velocity triangle according to the embodiment of the present invention. It is a figure which shows the relationship with (FIG. 3 (b)) in comparison with.

In the conventional impeller 100 shown in FIG. 3A, the peripheral velocity vector U, the absolute velocity vector V, and the relative velocity vector W are determined from the usage conditions of the impeller 100 such as the rotation speed, the flow rate, and the flow velocity, and the blade angle α is the axis. The angle is set to be 10 ° to 15 ° smaller than the angle θ formed by the flow direction and the relative velocity vector W. As a result, the conventional impeller 100 could not arbitrarily set the blade angle α.

In the impeller 1 of the present embodiment shown in FIG. 3B, when the peripheral velocity vector U is the same as that of the conventional impeller 100, the blade angle α is arbitrarily set, and the direction of the relative velocity vector W2 and the blade 5 are set. The shape of the flow velocity increasing body 6 is determined so that the sum (α + θ) of the angle θ (10 ° to 15 °) formed and the blade angle α coincides with the angle formed by the direction of the axial flow and the relative velocity vector W2. In such an impeller 1 of the present embodiment, the absolute velocity V2 of the fluid that has passed through the flow velocity increasing body 6 is made larger than the absolute velocity V1 of the fluid in the conventional impeller 100 (V2> V1), and the fluid passes through the flow velocity increasing body 6. By making the relative velocity W2 of the fluid formed larger than the relative velocity W1 of the fluid in the conventional impeller 100 (W2> W1), the blade angle α can be made smaller than the blade angle α of the conventional impeller 100. As a result, when the impeller 1 according to the present embodiment is manufactured by injection molding, the impeller 1 can be smoothly separated from the mold, and the productivity is improved.

In the impeller 1 according to the present embodiment having the above configuration, the flow velocity increasing body 6 increases the flow velocity of the fluid flowing between the blades 5 and 5, and the absolute velocity V2 and the relative velocity W2 of the fluid are adjusted according to the blade angle α. Since the value can be set to a preferable value and the fluid can be efficiently fed, the blade angle α can be determined regardless of the usage conditions of the impeller 1, and the degree of freedom in designing the blade 5 can be increased.

(Modification example 1)
FIG. 4 is a diagram showing a modified example 1 of the impeller 1 according to the present embodiment, and is an enlarged view showing a flow velocity increasing body 6 of the impeller 1.

As shown in FIG. 4, the impeller 1 according to the present modification has a plurality of rib-shaped protrusions 16 extending in a direction along the streamline of the fluid passing through the flow velocity increasing body 6 along the outer peripheral surface 6d of the flow velocity increasing body 6. It is formed. In the impeller 1 according to the present modification, the rib-shaped protrusions 16 formed on the outer peripheral surface 6d of the flow velocity increasing body 6 exert a rectifying function to reduce the flow resistance of the fluid passing through the flow velocity increasing body 6. Can be done.

FIG. 5 shows the efficiency of the impeller 1 according to the present modification (efficiency shown by the solid line in FIG. 5) and the efficiency of the conventional impeller (impeller without the flow velocity increasing body 6) (efficiency shown by the dotted line in FIG. 5). ) Is shown in comparison with. As shown in FIG. 5, when the impeller 1 according to the present modification is used for a centrifugal blower or the like, the efficiency can be improved as compared with the case where a conventional impeller is used.

The impeller 1 according to this modification exemplifies a mode in which a plurality of rib-shaped protrusions 16 are provided on the outer peripheral surface 6d of the flow velocity increasing body 6, but the present invention is not limited to this, and the streamline of the fluid passing through the flow velocity increasing body 6 is not limited to this. A groove extending in the direction along the rib-shaped protrusion 16 may be formed instead of the rib-shaped protrusion 16.

(Modification 2)
FIG. 6 is a diagram showing a modified example 2 of the impeller 1 according to the present embodiment, and is a vertical cross-sectional view of the impeller 1. Note that FIG. 6A is a vertical cross-sectional view of the impeller 1 showing a state in which the flow velocity increasing body 6 is separated from the central shaft portion 3. Further, FIG. 6B is a vertical cross-sectional view of the impeller 1 showing a state in which the flow velocity increasing body 6 is fixed to the central shaft portion 3.

As shown in FIG. 6, the flow velocity increasing body 6 is formed separately from the central shaft portion 3 of the impeller 1, and the female screw portion 17 penetrating along the axial center CL protrudes from the central hole 8 of the central shaft portion 3 of the impeller 1. It can be screwed into the male screw portion 20 of the shaft 18 to be fixed to the tip portion of the central shaft portion 3 of the impeller 1. The impeller 1 is fastened and fixed to the shaft 18 by the flow velocity increasing body 6 by screwing the flow velocity increasing body 6 into the male screw portion 20 of the shaft 18. Further, the impeller 1 is easily separated from the shaft 18 by separating the flow velocity increasing body 6 from the male screw portion 20 of the shaft 18.

(Modification example 3)
FIG. 7 is a diagram showing a modified example 3 of the impeller 1 according to the present embodiment, and is a vertical cross-sectional view of the impeller 1. Note that FIG. 7A is a vertical cross-sectional view of the impeller 1 showing a state in which the flow velocity increasing body 6 is separated from the central shaft portion 3. Further, FIG. 7B is a vertical cross-sectional view of the impeller 1 showing a state in which the flow velocity increasing body 6 is fixed to the central shaft portion 3.

As shown in FIG. 7, the flow velocity increasing body 6 is formed separately from the central shaft portion 3 of the impeller 1, and the male screw portion 21 integrally formed along the axial center CL is formed on the central shaft portion 3 of the impeller 1. By inserting the male screw portion 21 into the central hole 8 and screwing the male screw portion 21 into the female screw portion 22 of the shaft 18 fitted in the shaft hole 2 of the impeller 1, the male screw portion 21 can be fixed to the tip portion 13 of the central shaft portion 3. ing. The impeller 1 is fastened and fixed to the shaft 18 by the flow velocity increasing body 6 by screwing the male screw portion 21 of the flow velocity increasing body 6 into the female screw portion 22 of the shaft 18. Further, the impeller 1 is easily separated from the shaft 18 by separating the flow velocity increasing body 6 from the female screw portion 22 of the shaft 18.

(Other variants)
The impeller 1 according to this embodiment and each modification is not limited to the case where the whole is made of a synthetic resin material, and the whole may be made of a metal material, and a part (for example, the flow velocity increasing body 6) is made of metal. It may be formed of a material and the other part may be formed of a synthetic resin material.

Further, the impeller 1 according to the modified example 2 and the modified example 3 illustrates an embodiment in which the flow velocity increasing body 6 is fastened and fixed to the central shaft portion 3 with screws (male screw portions 20, 21, female screw portions 17, 22). The flow velocity increasing body 6 may be welded to the central shaft portion 3 or fixed with an adhesive.

1 ... Impeller, 3 ... Central shaft, 5 ... Blade, 6 ... Flow velocity increasing body, 6b ... Upstream part, 6c ... Downstream part, 13 ... Tip part, 14 ... Constriction part, CL …… Axial center

Claims (5)

It has a central shaft portion and a plurality of blades formed around the central shaft portion, and by rotating around the axial center of the central shaft portion, the blades are adjacent to each other from the direction along the axial center of the central shaft portion. In the impeller that causes the fluid that has flowed in between the blades to flow outward in the radial direction.
A flow velocity increasing body for increasing the flow velocity of the fluid flowing between the blades is provided at the tip portion of the central shaft portion on the fluid inflow side.
The flow velocity increasing body includes an upstream portion that gradually increases the outer diameter dimension from an end portion on the upstream side of the fluid in the flow direction toward the downstream side in the flow direction of the fluid, and a fluid on the upstream side portion and the central axis portion. It is a columnar body located between the tip portion on the inflow side and having a downstream portion having a constricted portion having a diameter smaller than the maximum outer diameter of the upstream portion.
An impeller characterized by that. The flow velocity increasing body was smoothly formed from the end on the upstream side in the flow direction of the fluid to the end on the downstream side in the flow direction of the fluid.
The impeller according to claim 1. In the flow velocity increasing body, a plurality of rib-shaped protrusions or grooves extending in the direction along the streamline are formed along the outer peripheral surface.
The impeller according to claim 1 or 2. The flow velocity increasing body is integrally formed on the central shaft portion.
The impeller according to any one of claims 1 to 3. The flow velocity increasing body was fixed to the central shaft portion.
The impeller according to any one of claims 1 to 3.

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