JP2985656B2 - Centrifugal multi-blade fan and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal multi-blade fan integrally formed of resin and a method of manufacturing the same, and is suitable for use in an air conditioner for automobiles and the like.

[0002]

2. Description of the Related Art A conventional centrifugal multi-blade fan of this type has been proposed in Japanese Patent Publication No. 5-74719. This conventional fan will be described with reference to FIGS. Boss part 1 coupled to the rotation axis of the drive source
Is provided at the center of the disc-shaped end plate 2, and a number of blades (wings) 3 are arranged on the outer peripheral side of the end plate 2 so as to be located on one circle centered on the boss portion 1. doing.

[0003] A shroud 4 is disposed at a position opposite to the end plate 2 in the axial direction of the blade 3, and the shroud 4 has an inner diameter D 1 larger than an outer diameter D 2 of the end plate 2. A suction side end 4a parallel to the axis extending in the axial direction, and a curved portion 4b that smoothly curves radially outward from the suction side end 4a and extends in the fan discharge direction are provided.

The boss 1, the end plate 2, the blade 3 and the shroud 4 are integrally formed of a resin, and the mating surface 5 of a split mold (forming die) for integrally forming a fan with the resin is used. A position on the blade 3 away from the minimum diameter portion D1 of the shroud 4 in the axial direction and the outer peripheral side of the end plate 2 (D2)
Is formed by a line connecting the two, so that the mating surface 5 is not positioned on the smooth curved portion 4b of the shroud 4, and a sharp edge is prevented from being generated in the molding die. Is being extended.

[0005]

However, in the above-mentioned conventional construction, the mating surface 5 of the upper and lower split molds (molding dies) for integrally molding the fan is separated from the minimum diameter portion D1 of the shroud 4 by a predetermined amount in the axial direction. Position on the blade 3 and the end plate 2
Is formed by a line connecting the outer peripheral side (D2) of the end plate 2 and the blade 3 with the difference (D1-D2) between the diameters D1 and D2 when the fan outer diameter is constant.
Therefore, the joint area between the blade 3 and the shroud 4 is inevitably reduced, and the strength of the product after molding is reduced.

For this reason, as shown in FIG. 5, it is necessary to set a reinforcing wall portion a at a joint portion between the end plate 2 and the blade 3.
In order to form the reinforcing wall portion, it is necessary to perform a special additional process such as electric discharge machining on the molding die, and an increase in die machining cost is inevitable. In view of the above, it is an object of the present invention to provide a centrifugal multi-blade fan having high product strength and capable of reducing the processing cost of a molding die, and a method of manufacturing the same.

[0007]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, a boss portion connected to a rotating shaft of a driving source and the boss portion are disposed at a center portion. A disc-shaped end plate 2 and an outer peripheral side of the end plate 2
A large number of blades 3 arranged on one circle centered on the rotation center of the boss portion 1 and a shroud 4 arranged on a portion of the blade 3 opposite to the end plate 2 in the axial direction. The shroud 4 has a suction-side end 4a having an inner diameter D1 substantially equal to the outer diameter D2 of the end plate 1 and extending substantially in parallel with an axis extending in the axial direction, and a radially outer side from the suction-side end 4a. And a curved portion 4b which is smoothly curved toward the fan discharge direction and is formed in the middle of the inner peripheral surface of the shroud at an inner peripheral surface of the suction side end portion 4a substantially parallel to the axis. A step 4c is formed to shift outward in the radial direction by a fixed amount δ, and an inner peripheral surface of the curved portion 4b is connected to a radially outer end of the step 4c, and the boss 1, the end plate 2, The blade 3 and the shroud 4 are integrally formed of resin. Adopt the technical means that.

[0008]

According to the first aspect of the present invention, since the above-mentioned technical means is provided, the inner diameter D1 of the suction-side end 4a of the shroud 4 and the mating surface G of the pair of molding dies A and B are provided. Even if the diameter D3 (D3 = D2) of the lower mold B is set to be equal to, that is, D3 = D1 = D2, the upper end of the lower mold B has a radial thickness by the predetermined amount δ. With the thickness corresponding to the predetermined amount δ, wear and damage of the upper end of the lower mold B can be prevented, and the life of the mold can be improved.

This eliminates the need to form a reinforcing wall a as in a conventional fan, so that there is no need to perform any special additional processing such as electric discharge machining on the mold, and therefore the machining cost of the mold can be reduced. Moreover, as described above, D3 = D1
= D2, the joint area between the shroud 4 and the blade 3 and the joint area between the blade 3 and the end plate 2 are increased for the same fan diameter by the difference between D1 and D2 in the conventional apparatus of FIG. As a result, the product strength after molding can be improved as compared with the conventional apparatus of FIG.

The effects of the first aspect of the present invention can be more effectively exerted by limiting the size or shape of the second to fourth aspects of the invention. According to the fifth aspect of the invention, the fan according to the first aspect of the invention can be favorably manufactured.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 3 show one embodiment of the present invention.
Is a cylindrical boss portion, on the inner peripheral side of which a rotary shaft of a drive source such as a motor (not shown) is inserted and connected.
2 is a disk-shaped end plate in which the boss 1 is disposed at the center,
Reference numeral 3 denotes a number of blades arranged at equal intervals on a single circle centered on the rotation center of the boss 1 on the outer peripheral side of the end plate 2, and the cross-sectional shape is a well-known slightly curved wing shape. Has become.

Reference numeral 4 denotes a shroud, which is disposed at a position opposite to the end plate 2 in the axial direction of the blade 3. The shroud 4 has a cylindrical suction-side end 4a having an inner diameter D1 substantially equal to the outer diameter D2 of the end plate 2 and being parallel to an axis extending in the axial direction. Then, a curved portion 4b is formed which is smoothly curved outward in the radial direction from the air downstream side of the suction side end portion 4a and extends in the fan discharge direction (arrow B direction). The entire shape of the curved portion 4b is in the shape of a trumpet whose diameter increases smoothly. Here, the shroud 4 is for guiding the air sucked into the opening end of the cylindrical suction side end 4a from the direction of arrow a smoothly to the blade 3 side.

Further, a ring for shifting the inner peripheral surface of the suction-side end 4a parallel to the axis by a predetermined amount δ (see FIGS. 1 and 3) radially outward in the middle of the inner peripheral surface of the shroud 4. A stepped portion 4c is formed, and an inner peripheral surface of the curved portion 4b is connected to a radially outer end of the stepped portion 4c. The boss 1, the end plate 2, the blade 3 and the shroud 4 are integrally formed of resin. The predetermined amount δ of the step 4c is 1 mm in this example, and the thickness t of the suction side end 4a is t. (T = 2 mm).

Next, a description will be given of a method of forming the centrifugal multi-blade fan according to the present embodiment having the above-described structure. FIG. 2 shows a pair of metal molds, wherein A is an upper mold and B is a lower mold. C denotes a space for forming the boss 1, D denotes a space for forming the end plate 2, and E denotes a space for forming the shroud 4. The molding space F of the blade 3 is indicated by a two-dot chain line for the convenience of drawing.

The present invention is characterized by a method of setting a mating surface (a mold cracking position) G in the blade 3 portion of the molding dies A and B. This point will be described in detail. The direction of removal is C in FIG. 2 and the direction of removal of the lower mold B is two directions in FIG. Needs to be set to be equal to or greater than the outer diameter D2 of.

On the other hand, in the present invention, as described above, the inner peripheral surface of the suction side end 4a parallel to the axis is radiused by a predetermined amount δ (see FIGS. 1 and 3) in the middle of the inner peripheral surface of the shroud 4. A ring-shaped step portion 4c for shifting outward in the direction is formed, and an inner peripheral surface of the curved portion 4b is connected to a radially outer end of the step portion 4c. Therefore, the suction side end 4 of the shroud 4
Even if the inner diameter D1 of a is set to be equal to the diameter D3 (D3 = D2) of the mating surface G, that is, even if D3 = D1 = D2, the upper end of the lower mold B is provided by the predetermined amount δ. The thickness in the radial direction can be provided, and the thickness corresponding to the predetermined amount δ can prevent the upper die of the lower die B from being worn and damaged, thereby improving the life of the molding die.

By the way, when the step portion 4c is not formed and the relationship of D3 = D1 = D2 is set as described above, the upper end of the lower die B is formed along the inner peripheral surface of the curved portion 4b of the shroud 4. A sharp edge is generated, and the sharp edge portion is worn out in a short time after the start of use, thereby causing a problem that the life of the mold is shortened. However, in the present invention, as described above, the suction side end A ring-shaped step portion 4c for shifting the inner peripheral surface of the portion 4a radially outward by a predetermined amount δ (see FIGS. 1 and 3) is formed, and the curved portion 4b is formed at a radially outer end of the step portion 4c. Are connected, the sharp edge is not generated in the mold even if the relationship of D3 = D1 = D2 is set as described above, and the life of the mold can be improved.

Further, by setting the relationship of D3 = D1 = D2 as described above, D3 = D1 = D1
1-D2, the joint area between the shroud 4 and the blade 3 and the blade 3 and the end plate 2 at the same fan diameter.
Can be increased, and as a result, the product strength after molding can be improved as compared with the conventional apparatus of FIG. According to experimental studies by the present inventors, it is desirable that the predetermined amount δ of the step portion 4c be set to 1 mm or more in order to secure the life of the mold. Further, it is desirable to set the predetermined amount δ to １ ／ t with respect to the thickness t of the suction side end 4a from the viewpoint of setting the shape of the shroud 4.

In the embodiment described above, the step 4c
Is formed so as to extend linearly outward in the radial direction by a predetermined amount δ from the inner peripheral surface of the suction-side end 4a, but the step 4c is slightly rounded toward the curved portion 4b (arc shape). Or a shape inclined in a tapered shape. In addition, the centrifugal multi-blade fan to which the present invention is applied is not limited to the one in which the discharge direction of the blown air is directed completely in the radial direction, and the discharge direction of the blown air is slightly directed in the axial direction from the radial direction. However, the present invention can be applied to a type generally called a mixed flow fan.

[Brief description of the drawings]

FIG. 1 is a sectional view of a centrifugal multi-blade fan showing one embodiment of the present invention.

FIG. 2 is a sectional view of a molding die for molding the fan of the present invention.

FIG. 3 is an enlarged sectional view of a main part of the fan of the present invention shown in FIG.

FIG. 4 is a sectional view of a conventional fan.

FIG. 5 is an enlarged sectional view of a main part of a conventional fan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boss part 2 End plate 3 Blade 4 Shroud 4a Suction side end part 4b Curved part 4c Step part A, B Mold D G G mating surface

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Miyata 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A-5-296194 (JP, A) JP-A-2- 136597 (JP, A) Japanese Utility Model 1984-58-9898 (JP, U) Japanese Utility Model 1987-158198 (JP, U) Japanese Utility Model Application 2-24096 (JP, U) (58) Field surveyed (Int. ⁶ , DB name) F04D 29/18-29/38

Claims (5)

(57) [Claims] A boss coupled to a rotation shaft of a drive source; a disk-shaped end plate having the boss disposed at a center; and a rotation center of the boss on an outer peripheral side of the end plate. And a plurality of blades arranged on one circle centered on a circle, and a shroud arranged at a portion opposite to the end plate in the axial direction of the blade. A suction-side end portion having an inner diameter substantially equal to the outer diameter and substantially parallel to an axis extending in the axial direction, and a curved portion smoothly curved radially outward from the suction-side end and extending in the fan discharge direction are formed. Further, a step is formed in the middle of the inner peripheral surface of the shroud to shift the inner peripheral surface of the suction side end parallel to the axis radially outward by a predetermined amount. An inner peripheral surface of the curved portion is connected to a direction outer end, and the boss portion Centrifugal multiblade fan which the end plate, the blade and the shroud is characterized in that it is integrally molded by resin. 2. The centrifugal multi-blade fan according to claim 1, wherein the predetermined amount of the step portion is approximately half the thickness of the suction side end. 3. The centrifugal multi-blade fan according to claim 1, wherein the predetermined amount of the step portion is 1 mm or more. 4. The centrifuge according to claim 1, wherein the step portion is formed to extend substantially linearly outward in the radial direction by a predetermined amount from an inner peripheral surface of the suction-side end portion. Formula multi-wing fan. 5. The method for producing a centrifugal multi-blade fan according to claim 1, wherein the shroud passes near the inner diameter of the suction-side end and near the outer diameter of the end plate. A method for manufacturing a centrifugal multi-blade fan, wherein the boss, the end plate, the blade, and the shroud are integrally formed of resin using a pair of molds having mating surfaces.