JPS6214397Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an airfoil type impeller used in an impeller for a centrifugal blower.

It is well known that impellers for centrifugal blowers use blades with an airfoil-shaped cross-sectional shape, but conventional blades are generally made by bending a flat plate into an airfoil shape, and the back plate of the impeller Attachment to the end ring or end ring is usually done by welding. For this reason, there have been problems in that the assembly of the impeller for producing the blades is time consuming and costly, and the welded parts are likely to be distorted or dislodged.

The present invention was developed with the aim of providing a blade material that is easy to manufacture and requires no effort to assemble an impeller. The main body and a plurality of screw fastening parts provided inside the main body while being connected to the main body are integrally formed by extrusion molding, and an internal thread for forming a female threaded hole for screw fastening is formed in the center of each screw fastening part. It is characterized in that all openings that are inevitably created by the child support portion during extrusion molding are opened toward the rear tail end of the main body. That is, the blade material of the present invention is manufactured by extrusion molding, which is suitable for mass production, so it is easy to manufacture, low cost, and lightweight, and it is easy to assemble because it is fastened with screws. At the same time, problems such as distortion that occur in the case of welding do not occur. Furthermore, in the case of extrusion molding,
Due to the core of the mold, an opening is always formed in the screw fixing part, and the strength of the screw fixation tends to be lower than that of a cylindrical type without an opening. However, in this invention, when the impeller rotates, Since the opening is provided toward the rear tail end where the centrifugal force and air resistance force are not applied, the opening has no practical effect on the strength of screwing, allowing for a strong assembly.

Next, an embodiment of the present invention will be described with reference to the drawings. Figures 1 and 2 show cross-sectional views of the blade material.
FIG. 1 shows an example of a device provided with two screw fastening portions, while FIG. 2 shows an example of a somewhat larger device provided with three screw fastening portions.

In the figure, reference numeral 1 denotes a hollow, thin-walled main body with an airfoil-shaped external cross-sectional shape, and reference numerals 2 and 3 denote screw fixing parts integrally provided inside the main body 1. The screw fixing part 2 has a substantially C-shaped cross section connected to the main body 1 by a rib 4 at the wide part, and the screw fixing part 3 is connected to the main body 1 at the narrow part at the rear end of the main body 1. They are formed continuously, and female threaded holes 2a, 3a into which screws are screwed are formed in the center of each screw fastening part 2, 3.
Reference numeral 5 denotes an opening of each screw fixing part 2, 3, and both are provided so as to open toward the tail end 1a at the rear of the main body 1. The blade material 6 of this embodiment has the above-described cross-sectional shape, and is manufactured by extrusion molding as a continuous body extending in a direction perpendicular to the drawing, and is made of aluminum, for example.

3 and 4 show an impeller for a centrifugal blower assembled using the above-mentioned blade material 6, 11 is a blade obtained by cutting the blade material 6 into a predetermined length, 12 13 is a back plate fixed to the boss 12 with rivets 14, 16 is an end ring, 16 is a mounting screw, and 17 is an impeller. The blade 11 is attached to the back plate 13 by inserting the mounting screw 16 into a screw hole (not shown) provided at a predetermined position and screwing it into the female threaded hole 2a, 3a of the screw stopper part 2, 3. The end ring 15 is attached in the same manner. The blades 11 are arranged at a pitch of, for example, 30 degrees, and are attached at a constant inclination in the diametrical direction with the tapered tail ends outward. They are installed alternately, shifted by a half pitch, as shown by the broken lines.

The impeller 17 rotates counterclockwise to push air from the center toward the periphery, but at this time, the impeller 11
As shown in Figure 3, there is a centrifugal force F ₁ in the radial direction.
and the air resistance force F ₂ due to the air flow. This air resistance force F ₂ is caused by the air on the blade 11
It is a combination of the force pushing outward the buoyant force generated by the shape of the airfoil, and even if its direction varies slightly depending on the rotational speed, it is always outward like the centrifugal force _F1 . That is,
It points toward the tail end of the blade 11 and never inward. Therefore, each screw fastening part 2, which has an opening 5 opened closer to the rear tail end 1a,
3 has a shape that can be stopped against these external forces, and no force is applied to the opening 5, and there is no possibility that the mounting screw 16 will loosen or the opening 5 will be damaged. It is. Note that although FIGS. 1 and 2 show an example in which the opening 5 is provided toward the tail end so as to match the direction of the arc-shaped reference line passing through the blade material 6 from the front end to the tail end, The opening 5 can be provided at a slightly inclined angle with respect to the reference line, and the screw fixing parts 2 and 3 can also be provided at an angle slightly inclined to the reference line.
It goes without saying that the shape and number of the parts can be appropriately selected as necessary.

As mentioned above, the blade material of the present invention has an airfoil-shaped hollow thin-walled main body and a screw fastening part inside the main body integrally formed by extrusion molding, and the opening of the screw fastening part is connected to the rear tail end of the main body. It is open toward the side, and can be manufactured easily at low cost.The impeller can be easily assembled using screws, and distortion does not occur, and it can be avoided by extrusion molding. This has the advantage that even if there is an opening in the screw fixing part, the installation strength does not decrease and a strong installation can be achieved.

[Brief explanation of drawings]

Figures 1 and 2 are respectively sectional views of embodiments of the present invention, Figure 3 is a partially cutaway cross-sectional view of an impeller using the blade material of the present invention, and Figure 4 is a partially cutaway front view of the same. It is. 1 is the main body, 1a is the tail end, 2 and 3 are screw fixing parts,
2a and 3a are female screw holes, 5 is an opening, 6 is a blade material, and 11 is a blade.

Claims (1)

[Scope of utility model registration request] Inside the hollow, thin-walled main body whose external cross-sectional shape has an airfoil shape through extrusion molding, multiple screw fastening parts are connected to the main body, each having a female threaded hole for screw fastening in the center. The blade material of the impeller for a centrifugal blower is formed integrally with the core support part for forming the female screw hole during extrusion molding. A blade material for an impeller for a centrifugal blower that opens toward the direction of the air.