JPS6347679Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in centrifugal blowers.

In a conventional centrifugal blower, as shown in FIGS. 1 and 2, fluid sucked in from a fan suction port 2 formed by a bell mouth 1 is pressurized by an impeller 6 consisting of a shroud 3, blades 4, and a main plate 5. After being charged and energized, it is discharged into a casing 7 and then through a discharge port 8.

However, in such a centrifugal blower, a large turning angle is required before the fluid sucked from the suction port 2 passes through the blades 4 and is discharged to the casing 7, so the fluid flow may separate on the surface of the shroud 3. This is a serious obstacle in achieving higher efficiency and lower noise of centrifugal blowers.

Therefore, conventionally, in order to solve such problems, the following two methods have been adopted.

That is, the first method is to increase the radius of curvature rs of the shroud 3 of the centrifugal blower to gradually change the direction of the fluid flow, as shown in FIG. 3, which is an enlarged view of a part of FIG. It is intended to do so.

The second method, as shown in FIG. 4, involves wrapping the bell mouth 11 and shroud 13 of the centrifugal blower and blowing out a jet from the gap δ between them.
The property of the jet flowing along the wall surface (Coanda effect) is utilized to prevent separation of the fluid flow on the shroud surface.

In addition, in FIG. 4, 14, 15 and 17
indicate the blade, main plate, and casing, respectively.

However, these two methods have the following drawbacks and cannot be said to be optimal methods.

That is, in the first method shown in FIG. 3, it is necessary to set the radius of curvature rs of the shroud 3 of the centrifugal blower to be quite large, so that the distance L between the end of the bell mouth 1 and the outlet of the blade 4 is As the size increases, the depth of the casing 7 inevitably increases, creating a problem that the centrifugal blower cannot be made more compact.

In the second method shown in FIG. 4, unlike the method shown in FIG. 3, the end of the bell mouth 11 and the blade 14
However, if the gap δ between the shroud 13 and the bell mouth 11 is large, the speed of the jet will slow down and the fluid flow will not follow the wall surface very well, so it is necessary to make this gap δ quite small, which requires high assembly precision and causes the problem of increased costs.

The present invention was devised to solve these conventional problems, and it is possible to improve the surface area of the shroud without increasing the radius of curvature of the shroud of a centrifugal blower or reducing the gap between the shroud and the bell mouth. The object of the present invention is to provide a means that can effectively prevent separation of fluid flows in the air.

According to the present invention, the guide vanes are installed concentrically between the bell mouth and the shroud of the centrifugal blower. This system generates a plurality of jets with weak adhesion force, thereby causing the fluid flow to adhere to the shroud surface, thereby reliably preventing separation of the fluid flow.

Therefore, according to the present invention, there is no need to reduce the gap between the shroud and the bell mouth in order to prevent fluid flow separation, so there is no need to increase assembly accuracy, and the radius of curvature of the shroud can also be increased. Since it is not necessary, there is no need to increase the distance between the bell mouth end and the blade outlet, which makes it possible to provide a compact centrifugal blower that is easy to assemble.

Of course, according to the present invention, separation of the fluid flow on the shroud surface is reliably prevented, thereby providing a centrifugal blower with high efficiency and low noise.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 5, similar to the conventional example shown in FIGS. 1 to 4, in the centrifugal blower, fluid sucked from a bell mouth 21 passes through blades 24 supported by a shroud 23 and a main plate 25 to a casing 27. It is starting to be expelled.

Therefore, according to the present invention, the guide vane 29 is installed concentrically between the bell mouth 21 and the shroud 23, and the guide vane 29 allows the flow to flow at a high speed and has a strong adhesion force to the shroud surface due to the commander effect. A plurality of jets having a lower speed and weaker adhesion force than a single jet (as shown in FIG. 4) are generated, thereby causing the fluid flow to adhere to the surface of the shroud 23.

As described above, the present invention takes into account that the adhesion force of the jet to the wall (shroud surface) due to the commander effect is stronger as the flow velocity increases, and the present invention is designed to improve the bond between the bell mouth 11 and the shroud 13 as in the conventional example shown in FIG. Instead of reducing the gap δ to generate a single jet with a higher flow velocity and stronger adhesion force to attach the fluid flow to the surface of the shroud 13, the bell mouth 21 and the shroud 23 are attached to the surface of the shroud 13 as shown in FIG. A guide vane 29 installed concentrically between the shroud 23 generates a plurality of jets with low speed and weak adhesion, thereby causing the fluid flow to adhere to the surface of the shroud 23 and reliably preventing separation of the fluid flow. This is how it was done.

Therefore, according to the present invention, the bell mouth 21
Since the gap between the shroud 23 and the shroud 23 can be increased to reduce the flow velocity of the jet, high precision is not required for assembly, and an increase in costs can be avoided.

Furthermore, separation of the fluid flow on the shroud surface can be reliably prevented without increasing the radius of curvature of the shroud 23 as in the conventional example shown in FIG. There is no need for the distance L to be large, and the dimensions may be similar to those of the conventional example shown in FIG. 4, so that the centrifugal blower can be made more compact.

As described above, the present invention provides a centrifugal blower that is extremely useful industrially.

[Brief explanation of drawings]

1, 2, and 3 are a front view, a sectional view, and a partially enlarged view showing an example of a conventional centrifugal blower, and FIG. 4 is a diagram corresponding to FIG. 3, showing another example of a conventional centrifugal blower. FIG. 5 is a diagram corresponding to FIGS. 3 and 4, showing an example of a centrifugal blower according to the present invention. 21... Bellmouth, 23... Shuroud, 2
4...Blade, 25...Main plate, 27...Casing, 29...Guide vane.

Claims (1)

[Scope of utility model registration request] A centrifugal blower characterized by a guide vane installed concentrically between the bell mouth and shroud of the centrifugal blower.