JP3322744B2 - Solid impeller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller for a centrifugal pump, and more particularly to a solid impeller used for a pump having a small flow rate and a high head, that is, a pump having a low specific speed.

[0002]

2. Description of the Related Art In general, it is known that a so-called solid impeller is used in a low specific speed pump in order to prevent a decrease in pump efficiency due to a relative circulation of a handling liquid generated in an impeller passage. It is.

[0003] That is, in FIGS. 8 and 9, the solid impeller 10 is provided with a suction part 12 in the center and a discharge part 14 on the outer periphery. A plurality (eight in the illustrated example) of radial passage holes 22 extending radially outward from the suction port 18 toward the discharge port 20 of the discharge section 16 is provided. In addition, as shown in the figure, each flow path hole 22 is generally formed in a straight shape in the radial direction, and usually has respective dimensions (width and height) w ₁ , w of the suction port 18 and the discharge port 20. ₂ and h _1, h
₂ is set identically.

Therefore, according to the solid impeller 10 having such a configuration, unlike the ordinary impeller, the impeller flow path is constituted only by the straight perforated flow path hole 22, so that the low specific speed pump is used. Also in this case, the relative circulation of the handled liquid in the impeller flow passage hole is prevented, so that a decrease in pump efficiency due to this can be prevented.

[0005]

However, the conventional solid impeller described above generally has the following drawbacks.

That is, in the above-mentioned conventional solid impeller, as described above, the handled liquid flow path is constituted only by the impeller flow path hole formed inside the impeller body.
Therefore, the relative circulation of the handled liquid in the impeller flow passage hole is prevented, thereby preventing a decrease in pump efficiency (relative circulation loss). However, on the other hand, as a matter of course, disc friction loss (decrease in pump efficiency) due to the impeller body itself is inevitable.

That is, the disc friction loss Pd is obtained by the following formula (1) according to Friedler.

Pd = K ₁ γu ³ D (D + 5B ₂ ) (1) where K ₁ : coefficient γ: specific weight of liquid (Kg / m ³ ) u: peripheral speed (m / s) D: impeller body outer diameter (m) B ₂ = h ₂ + 2t: impeller body outer peripheral part thickness (m) Here, coefficient K ₁ , specific weight γ, peripheral speed u, and outer diameter D are:
Is determined themselves from the pumped fluid properties and the specific speed of the outer peripheral portion thickness B ₂ is optionally set within a range satisfying a predetermined condition.

However, in the conventional solid impeller, as shown in FIG. 8 and FIG.
2 is formed in a straight shape in which the respective dimensions w ₁ , w ₂ , h ₁ and h ₂ are set to be the same, so that the thickness B ₂ must be set relatively large. This is because if the thickness B ₂ is set small, the height h ₂ , and thus the suction port 1
8, the height h ₁ and the width w ₁ are reduced, and the suction performance (predetermined conditions) is impaired. As a result, the disc friction loss P
d had reached a considerable size.

As described above, in the conventional solid impeller described above, although the relative circulation loss of the handling liquid can be prevented, the disk impulse loss of the impeller body newly occurs, so that the desired pump efficiency is sufficiently improved. Was not achieved.

Therefore, a suction portion is provided at the center of the solid impeller and a discharge portion is provided at the outer periphery. The inside of the rotary disk-shaped impeller body extends radially outward from the suction portion toward the discharge portion. In the solid impeller having a plurality of radial flow passage holes formed therein, the flow passage hole has at least a dimension in the thickness direction of the impeller body outside the radial direction so that its cross-sectional area gradually decreases outward in the radial direction. The impeller body is formed so as to gradually taper toward the outer side, and the thickness of the impeller body is gradually reduced outward in the radial direction.

In this case, the flow path hole can be formed in a tapered shape in which the width dimension in the plane of the impeller body is gradually tapered outward in the radial direction. Further, the flow path hole can be formed such that the front side in the rotation direction of the impeller main body is tapered with respect to the radial straight line. In addition, the channel hole
The center axis may be set to be perpendicular to the rotation axis.

The thickness of the impeller main body is gradually reduced toward the outer peripheral portion by forming the impeller flow passage hole in a tapered shape gradually tapering outward in the radial direction. Therefore, according to this example, the relative circulation of the handling liquid in the impeller passage hole is prevented, and the disk friction loss of the impeller body is reduced as much as possible.

Although overlapping, the description will be briefly given again with reference to FIG.
2 and FIG. 2, the solid impeller 10 is provided with a suction part 1 inside a rotary disk-shaped impeller body 16 having a suction part 12 at a central part and a discharge part 14 at an outer peripheral part.
A plurality (eight in the illustrated example) of radial passage holes 22 extending radially outward from the second suction port 18 toward the discharge port 20 of the discharge section 16 is formed.

The flow passage hole 22 has at least a dimension h in the thickness direction (height) of the impeller body 16 in the radially outward direction such that its cross-sectional area gradually decreases outward in the radial direction. , The suction port height h ₁ ′ is gradually tapered to the discharge port height h ₂ ′. Thus, the thickness B of the impeller body 16 ', towards radially outwards, suitably thin thickness B _2' gradually decreased so as to.

In this example, the width dimension w of the flow path hole 22 in the plane of the impeller body 16 also gradually tapers outward from the suction port width w ₁ ′ to the discharge port width w ₂ ′. It is formed in a tapered shape. In this case, the dimensions w ₁ ′ and h ₁ ′ and w ₂ ′ and h ₂ ′ are set to the same dimensions, respectively, and the suction port width w ₁ ′ is
2 is set to the maximum allowable dimension. Further, the tapered shape of the flow passage hole 22 formed by the dimensions w ₁ ′ and w ₂ ′ and h ₁ ′ and h ₂ ′ allows the flow of the handling liquid in the flow passage hole 22 to smoothly increase. , So as not to generate a circulating flow.

As described above, according to this example, the thickness B ₂ ′ = h ₂ ′ + 2t (see FIG. 2) of the outer peripheral portion of the impeller body 16 is compared with the conventional thickness B ₂ (see FIG. 9). And set small enough. Therefore, as is clear from the experimental results described below, the occurrence of the disc friction loss Pd (see the above formula (1)) is reduced as much as possible, and the occurrence of the relative circulation loss of the handled liquid is described above. In this way, it is reliably prevented as in the case of the conventional straight flow path hole. Thus, it is clear that an improvement in pump efficiency can be sufficiently achieved. In addition, since the size (area) of the suction port can be set sufficiently without being restricted, the suction performance can be improved. Further, there is an advantage that the impeller body is light in weight and can be precision cast relatively easily.

FIGS. 3 to 5 show the performance (solid line) of the solid impeller achieved in this way and the performance (dotted line) of the conventional solid impeller in the required flow rate range (0 to 15).
(0 l / min). That is, FIG. 3 shows that although the flow rate Q-head H curve hardly changes, the efficiency η (%) is improved especially in a small flow rate range. FIG. 4 shows that the suction performance (NPSHreq) is improved. In FIG. 5, the shaft power (K
W) is shown to improve especially in the small flow rate region. Note that this shaft power is mainly due to a reduction in disc friction loss.

[0019]

According to the present invention, there is provided a solid impeller having a suction portion provided at a center portion and a discharge portion provided at an outer peripheral portion inside a rotating disk-shaped impeller main body, from the suction portion to the discharge portion. In a solid impeller having a plurality of radial flow passage holes extending radially outward toward
The flow path hole is formed so that the width dimension in the plane of the impeller body is gradually tapered toward the outside in the radial direction, and the thickness of the impeller body is gradually reduced toward the outside in the radial direction, Further, the flow passage hole is characterized in that the front side in the rotation direction of the impeller body is inclined linearly in the radial direction, and the hole is formed such that the rear side in the rotation direction is tapered in parallel with the center line of the impeller plane. I do.

In this case, the flow path hole can be set so that its central axis is perpendicular to the rotation axis.

[0021]

The solid impeller according to the present invention is provided with a suction portion at the center and a discharge portion at the outer periphery inside a rotating disk-shaped impeller body, which is radially outward from the suction portion toward the discharge portion. In a solid impeller having a plurality of radial flow passage holes extending therethrough, the flow passage hole is formed such that a width dimension in a plane of the impeller main body is gradually tapered outward in a radial direction, and the impeller main body has a tapered shape. The thickness is configured to gradually decrease radially outward, and further, the flow path hole is inclined linearly in the radial direction on the front side in the rotational direction of the impeller body, and the hole is impeller on the rear side in the rotational direction. By forming the tapered shape parallel to the center line of the plane, it is possible to prevent the relative circulation loss caused by the circulating flow of the handling liquid in the impeller passage hole, and to reduce the outer peripheral thickness of the impeller body. It is possible to suppress disc friction loss due to. Therefore, according to the solid impeller according to the present invention, the desired pump efficiency can be sufficiently maintained.

Next, an embodiment of a solid impeller according to the present invention will be described with reference to FIGS. In the present embodiment, in the above configuration example (FIGS. 1 and 2), the flow path hole 22 is inclined linearly in the radial direction on the front side in the rotation direction R of the impeller main body 16, and the hole is positioned rearward in the rotation direction. The side is formed in a tapered shape parallel to the center line of the impeller plane (see FIG. 6). In this case, the flow path hole 2
It is preferable that the center axis of the second motor is configured to be perpendicular to the rotation axis S (see FIG. 7). In the present embodiment, the dimensions of the suction port heights h ₁ ′ and h ₂ ′ and the suction port widths w ₁ ′ and w ₂ ′ can be set in the same manner as in the previous embodiment. It is clear that the obtained operation and effect can be exhibited in the same manner as in the above-described configuration example, and thus detailed description is omitted.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and many design changes can be made without departing from the spirit of the present invention.

[0024]

According to the solid impeller according to the present invention, a suction portion is provided at a center portion and a discharge portion is provided at an outer peripheral portion inside a rotating disk-shaped impeller main body in a radial direction from the suction portion toward the discharge portion. In the solid impeller having a plurality of radially extending flow passage holes extending outward, the flow passage hole is formed such that a width dimension in a plane of the impeller body is gradually tapered outward in the radial direction, and the impeller The thickness of the main body is configured to gradually decrease radially outward,
Further, the flow path hole is inclined linearly in the radial direction on the front side in the rotation direction of the impeller body, and the hole is formed on the rear side in the rotation direction in a tapered shape parallel to the center line of the impeller plane. Relative circulation loss due to the circulation flow of the handling liquid in the hole can be prevented,
Disc friction loss due to the outer peripheral portion thickness of the impeller body can be suppressed. Therefore, according to the solid impeller according to the present invention, the desired pump efficiency can be sufficiently maintained.

Further, according to the solid impeller of the present invention, the size (area) of the suction port can be sufficiently set without restriction, so that the suction performance can be improved and the impeller body can be downsized. It has the advantage that it is lightweight and can be precision cast relatively easily.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration example of a solid impeller.

FIG. 2 is a sectional view taken along line II-II of the solid impeller shown in FIG.

FIG. 3 is a characteristic diagram showing a comparison between pump efficiency and head characteristics of the solid impeller shown in FIG. 1 and another conventional solid impeller.

FIG. 4 is a characteristic diagram showing a comparison of suction characteristics between the solid impeller shown in FIG. 1 and a conventional solid impeller.

FIG. 5 is a characteristic diagram showing a comparison of shaft power characteristics between the solid impeller shown in FIG. 1 and a conventional solid impeller.

FIG. 6 is a plan view showing an embodiment of a solid impeller according to the present invention.

FIG. 7 is a sectional view taken along line VII-VII of the solid impeller shown in FIG. 6;

FIG. 8 is a plan view showing a configuration of a conventional solid impeller.

9 is a sectional view of the solid impeller shown in FIG. 8, taken along line IX-IX.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Solid impeller 12 Suction part 14 Discharge part 16 Impeller main body 18 Suction port 20 Discharge port 22 Flow path hole

Claims (2)

(57) [Claims] 1. A plurality of radially outward extending from the suction portion to the discharge portion inside a rotating disk-shaped impeller body having a suction portion provided at a central portion and a discharge portion provided at an outer peripheral portion. In a solid impeller having a radial flow passage hole formed therein, the flow passage hole is formed in such a manner that a width dimension in a plane of the impeller body is gradually tapered toward a radially outward direction, and a thickness of the impeller body is radially outward. The flow path hole is further inclined in the radial direction on the front side in the rotational direction of the impeller body, and the hole is parallel to the center line of the impeller plane on the rear side in the rotational direction. Solid impeller formed in the shape of a taper. 2. The solid impeller according to claim 1, wherein the flow path hole is set so that its central axis is perpendicular to the rotation axis.