Plug Fan

Abstract

To provide a plug fan which can reduce noise, and allows a blade to be manufactured at a low cost by press-bending.SOLUTION: A side plate 2 has a suction port 5 which is opened toward a front side in a fan axial direction, has a blowout port 6 which is opened toward the outside of a fan radial direction between an external peripheral edge of a main plate 3 and an external peripheral edge of the side plate 2. In a blade plate 4, a blade front edge 7 at an airflow inlet side ahead of the fan rotation direction is located inside the fan radial direction, a blade rear edge 8 at an airflow outlet side behind the fan rotation direction is located outside the fan radial direction, and the main plate 3 has an external peripheral part 9 which is spread to the outside of the blade rear edge 7 in the fan radial direction, and has a main plate opening edge 10 which is warped to a rear side in the fan axial direction at the external peripheral part 9.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plug fan used in an air conditioner or the like. [Background technology]

[0002] Conventionally, a radial fan wheel, such as that described in Patent Document 1, has blades that are inclined opposite to the direction of rotation, and the outer edge regions of the top and bottom disks protrude beyond the effective diameter of the blades, and the effective and outer diameters of the blades convert the kinetic energy of the fluid between the bottom and top disks into pressure potential.

[0003] Furthermore, the turbofan described in Patent Document 2 has a main plate having a boss fixed to the rotating shaft of the motor, a shroud forming an air intake guide wall, and multiple blade members molded separately from thermoplastic resin. The main plate has fitting portions for the multiple blade members, and the shroud also has fitting portions for the multiple blade members, and the multiple blade members are arranged parallel to the rotating shaft and integrated with the main plate and shroud by ultrasonic welding.

[0004] Furthermore, the turbofan impeller described in Patent Document 3 includes a main plate that engages with a drive source, a side plate that is disposed opposite the main plate, and a plurality of blades that are arranged in the circumferential direction between the main plate and the side plate. When viewed from the leading edge side, the inlet inclination angle of each blade, which the leading edge forms with the main plate, is set to 78° to 89°, and the outlet inclination angle of the blade, i.e., the angle that the trailing edge forms with the main plate when viewed from the trailing edge side, is set to 90°. [Patent Document 1] Special Table 2006-51936 [Patent Document 2] Patent Publication No. 2016-84743 [Patent Document 3] Patent No. 4934467 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] Generally, plug fans can achieve high static pressure efficiency without a housing, but they are disadvantageous in terms of noise, so noise control measures must be taken on the building side where the air conditioner or equipment is located.

[0006] Using blades with a blade cross section shaped like an airfoil can achieve low noise and high efficiency, but manufacturing blades with a blade cross section requires resin molding and multiple bending processes, which places restrictions on the manufacturing methods and materials that can be used.

[0007] The present invention is devised to solve the above-mentioned problems, and aims to provide a plug fan that reduces noise and has blades that can be produced at low cost by press bending. [Means for solving the problem]

[0008] In order to solve the above problems, the plug fan of the present invention has a front side plate and a rear main plate that face each other in the fan axial direction, and a plurality of blade plates arranged around the fan axis between the main plate and the side plate, the side plate has an intake port that opens forward in the fan axial direction, and an outlet port that opens radially outward in the fan direction between the outer circumferential edges of the main plate and the side plate, the blade plate has a leading edge on the airflow inlet side forward in the fan rotation direction that is positioned radially inward in the fan direction, and a trailing edge on the airflow outlet side rearward in the fan rotation direction that is positioned radially outward in the fan direction, the main plate has an outer periphery that extends radially outward beyond the trailing edge of the blade, and has a main plate opening edge on the outer periphery that is curved rearward in the fan axial direction. The blades are flat in the blade span direction from the main plate to the side plate, and curved in the blade chord direction from the leading edge to the trailing edge of the blade, curving forward in the fan rotation direction. The inlet angle of the leading edge of the blade and the outlet angle of the trailing edge of the blade are different on the main plate side and the side plate side, with the inlet angle on the side plate side being smaller than the inlet angle on the main plate side, and the outlet angle on the side plate side being smaller than the outlet angle on the main plate side. It is characterized by:

[0009] In the plug fan of the present invention, the blades are characterized in that the entire blade has an inclination angle with respect to the fan axis and spreads outward in the radial direction of the fan from the main plate toward the air inlet.

[0010] In the plug fan of the present invention, the blade plate has a constant inclination angle with respect to the fan axis from the leading edge to the trailing edge of the blade.

[0011] In the plug fan of the present invention, the blades are characterized by being inclined at a constant angle in the range of 7° to 9° relative to the fan axis.

[0012] In the plug fan of the present invention, the blades are characterized in that the side plate side is located radially outward of the main plate side in the fan radial direction, and the inner diameter of the blades on the main plate side at opposing positions in the blade blade blade blade width direction from the main plate to the side plate is smaller than the inner diameter of the blades on the side plate side.

[0014] In the plug fan of the present invention, the blade plate is characterized in that the blade plate blade width direction from the main plate to the side plate is flat, the blade plate chord length direction from the leading edge of the blade to the trailing edge of the blade is curved forward in the direction of fan rotation, and a pick-up portion is provided on the leading edge side of the blade that is curved radially outward of the blade plate camber line. [Effects of the Invention]

[0015] As described above, according to the present invention, the main plate has an opening edge that curves rearward in the fan axial direction on the outer periphery that extends radially outward beyond the trailing edge of the blades, thereby enlarging the outlet opening and increasing the outlet width, thereby improving the maximum efficiency of the blower on the large air volume side, and thus expanding the range of use of the plug fan.

[0016] Furthermore, the entire blade plate, that is, not only the leading edge of the blade but also the blade leading edge to the trailing edge of the blade, has an inclination angle with respect to the fan axis, and is configured to spread outward in the radial direction of the fan from the main plate toward the suction port, so that the blade plate spreads so that the suction port side is open, and pressure fluctuations at the fan outlet at the trailing edge of the blade can be alleviated, thereby suppressing noise.

[0017] Furthermore, the blades may be configured to have a constant inclination angle relative to the fan axis from the leading edge to the trailing edge, and the constant inclination angle relative to the fan axis may be in the range of 7° to 9°, for example 8°, to optimize noise reduction.

[0018] Furthermore, the inner diameter of the blades on the main plate side is smaller than the inner diameter of the blades on the side plate side, thereby improving the maximum efficiency of the blower.

[0019] Furthermore, the inlet angle of the leading edge of the blade and the outlet angle of the trailing edge of the blade are different on the main plate side and the side plate side, with the inlet angle on the side plate side being smaller than the inlet angle on the main plate side and the outlet angle on the side plate side being smaller than the outlet angle on the main plate side, thereby reducing noise, improving static pressure on the high airflow side, and expanding the range of use of the plug fan. Note that here, the inlet angle is the angle between the normal to the tangent to the camber line at the leading edge of the blade and the line from the fan axis to the leading edge of the blade, and the outlet angle is the angle between the normal to the tangent to the camber line at the trailing edge of the blade and the line from the fan axis to the trailing edge of the blade.

[0020] Furthermore, the blade plate has a pick-up portion on the blade leading edge side that is warped radially outward from the warp line of the blade plate, thereby improving the maximum efficiency of the blower. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view of a plug fan according to an embodiment of the present invention; [Figure 2] FIG. 10 is a partially cutaway front view of the plug fan according to the embodiment. [Figure 3] FIG. 3 is a perspective view of the plug fan according to the embodiment; [Figure 4] FIG. 10 is a front view of the plug fan without a side panel according to the embodiment. [Figure 5] FIG. 4 is a schematic diagram showing the inclination of the blades of the plug fan according to the embodiment. [Figure 6] FIG. 4 is a front view of the blades of the plug fan according to the embodiment. [Figure 7] FIG. 10 is an enlarged view of a main part of the plug fan according to the embodiment; [Figure 8] FIG. 2 is a schematic diagram showing a main part of a blade plate of the plug fan according to the embodiment; [Figure 9] FIG. 4 is a schematic diagram showing the inlet angle and outlet angle of the blades of the plug fan according to the embodiment. [Figure 10] Schematic diagram showing the inlet and outlet angles of the blades of a plug fan shown as a conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

[0022] 1 to 9, a plug fan 1 has a front side plate 2 and a rear main plate 3 that face each other in the fan axial direction, and multiple blades 4 arranged around the fan axis between them.

[0023] The side plate 2 has an intake port 5 that opens forward in the axial direction of the fan, and an outlet port 6 that opens outward in the radial direction of the fan between the outer periphery of the main plate 3 and the outer periphery of the side plate 2.

[0024] The blade plate 4 has a blade leading edge 7 on the airflow inlet side forward in the fan rotation direction, which is located radially inward in the fan direction, and a blade trailing edge 8 on the airflow outlet side backward in the fan rotation direction, which is located radially outward in the fan direction. The main plate 3 has a main plate opening edge 10 that is curved rearward in the fan axial direction at an outer periphery 9 that extends radially outward beyond the blade trailing edge 8.

[0025] 5, the main plate opening edge 10 at the outer periphery 9 of the main plate 3 is curved backward in the direction of the fan axis and expands to φ1.13D, compared to the nominal diameter φD of the fan (the diameter of the path that the blade trailing edge 8 on the main plate 3 traces around the fan axis). This expands the opening of the outlet 6, and the outlet width increases from 0.3D to 0.31D.

[0026] In this way, the main plate 3 has a main plate opening edge 10 that curves backward in the fan axial direction at the outer peripheral portion 9 that extends radially outward from the blade trailing edge 8, which enlarges the opening of the outlet 6 and increases the outlet width, improving the maximum efficiency of the blower by 3.4% on the large air volume side.

[0027] The improvement in fan efficiency was evaluated using the blade plate 50 shown in Figure 10 (details will be described later) and a plug fan with a main plate 3 size of 1.07D relative to the nominal diameter φD of the fan as a comparison control.

[0028] The blade plate 4 is made by press bending steel plate, with the blade plate width direction from the main plate 3 to the side plate 2 being flat, and the blade plate chord direction from the blade leading edge 7 to the blade trailing edge 8 being curved forward in the fan rotation direction. Therefore, compared to blades with conventional aerofoil cross-section shapes, the initial investment is small and the production can be done at low cost.

[0029] As shown in Fig. 7, the entire blade plate 4 has an inclination angle θ with respect to the fan axis, and spreads outward in the radial direction of the fan from the main plate 3 toward the air inlet 5. In Fig. 7, the case where the entire blade plate is arranged parallel to the fan axis is shown by a two-dot chain line, and the inclination angle θ is shown for comparison.

[0030] Although the inclination angle θ may vary from the leading edge 7 to the trailing edge 8, in this example, the blade plate 4 has a constant inclination angle θ relative to the fan axis from the leading edge 7 to the trailing edge 8. The inclination angle θ can be set in the range of 7° to 9°, with 8° being optimal.

[0031] In this way, the entire blade plate has a constant inclination angle θ relative to the fan axis, and is configured to spread radially outward from the main plate 3 toward the suction port 5, so that the blade plate 4 spreads so that the side toward the suction port 5 opens, thereby mitigating pressure fluctuations at the fan outlet at the blade trailing edge 8 and suppressing noise, and the noise suppression effect can be optimized by setting the constant inclination angle θ to 8°.

[0032] 7, the side of the blade plate 4 on the side of the side plate 2 is positioned radially outward of the side of the main plate 3 in the fan radial direction, and the blade inner diameter d1 on the side of the main plate 3 at positions facing each other in the blade plate blade span direction from the main plate 3 to the side plate 2 is smaller than the blade inner diameter d2 on the side of the side plate 2. In this way, the blade inner diameter d1 on the side of the main plate 3 is smaller than the blade inner diameter d2 on the side of the side plate 2, thereby improving the maximum efficiency of the blower by 1.4%.

[0033] As shown in FIG. 9, the blade plate 4 has a chord length C1 of 0.37D on the side of the side plate 2 and a chord length C2 of 0.4D on the side of the main plate 3, and the inlet angles θ1 and θ2 of the blade leading edge 7 and the outlet angles θ3 and θ4 of the blade trailing edge 8 are different between the side plate 2 side and the main plate 3 side.

[0034] The inlet angle θ1 on the side plate 2 side is smaller than the inlet angle θ2 on the side of the main plate 3, and the outlet angle θ3 on the side plate 2 side is smaller than the outlet angle θ4 on the side of the main plate 3. The inlet angles θ1 and θ2 are the angles between the normals N1 and N2 to the tangents to the camber lines at the blade leading edge 7 and the lines L1 and L2 that extend from the fan axis to the blade leading edge 7, and the outlet angles θ3 and θ4 are the angles between the normals N3 and N4 to the tangents to the camber lines at the blade trailing edge 8 and the lines L3 and L4 that extend from the fan axis to the blade trailing edge.

[0035] In this way, the inlet angle θ1 on the side panel 2 side is smaller than the inlet angle θ2 on the main panel 3 side, and the outlet angle θ3 on the side panel 2 side is smaller than the outlet angle θ4 on the main panel 3 side, which reduces noise, improves static pressure on the high air volume side, and expands the range of use of the plug fan.

[0036] Incidentally, in the comparative slat plate 50 shown in FIG. 10, the chord length C3 is 0.36D, the inlet angle θ5 is smaller than the inlet angles θ1 and θ2 of the embodiment, and the outlet angle θ6 is larger than the outlet angles θ3 and θ4 of the embodiment.

[0037] 8, the blade plate 4 has a pick-up portion 11 that is warped radially outward from the warp line of the blade plate 4 on the blade leading edge 7 side. As a result of the blade plate 4 having the pick-up portion 11 in this way, the maximum efficiency of the blower is improved by 0.7%.

[0038] As described above, the plug fan of this embodiment improved the maximum fan efficiency by 5.5% overall and reduced noise levels by 5 dB(A) compared to the comparative plug fan shown in FIG. [Explanation of symbols]

[0039] 1 plug fan 2 Side panels 3 Main plate 4 Slats 5 Intake port 6 Air outlet 7. Leading edge of blade 8 Trailing edge of blade 9 Outer periphery 10 Main plate opening edge 11. Welcome Section 50 Comparison slats D Nominal diameter (diameter) θ Tilt angle d1, d2: inner diameter of blade θ1, θ2, θ5 Entrance angle θ3, θ4, θ6 Exit angle N1, N2, N3, N4 normals L1, L2, L3, L4 lines C1, C2, C3 chord length

Claims

1. The fan has a front side plate and a rear main plate that face each other in the fan axial direction, and a plurality of blades that are arranged around the fan axis between the main plate and the side plate, the side plate has an intake port that opens forward in the fan axial direction, and an outlet port that opens outward in the fan radial direction between the outer circumferential edge of the main plate and the outer circumferential edge of the side plate, The blade plate has a leading edge on the airflow inlet side forward in the fan rotation direction located on the inner side in the fan radial direction, and a trailing edge on the airflow outlet side backward in the fan rotation direction located on the outer side in the fan radial direction, the main plate has an outer circumferential portion that extends outward in the fan radial direction relative to the blade trailing edge, and the outer circumferential portion has a main plate opening edge that is warped rearward in the fan axial direction; This plug fan is characterized in that the blades are flat in the blade span direction from the main plate to the side plates, and are curved in the blade chord direction from the leading edge to the trailing edge, curving forward in the direction of fan rotation; the inlet angle of the leading edge of the blade and the outlet angle of the trailing edge of the blade are different on the main plate side and the side plate side, the inlet angle on the side plate side being smaller than the inlet angle on the main plate side, and the outlet angle on the side plate side being smaller than the outlet angle on the main plate side.

2. 2. The plug fan according to claim 1, wherein the entire blade has an inclination angle with respect to the fan axis, and spreads outward in the radial direction of the fan from the main plate toward the air inlet.

3. 3. The plug fan according to claim 2, wherein the blade plate has a constant inclination angle with respect to the fan axis from the leading edge to the trailing edge of the blade.

4. 4. The plug fan according to claim 3, wherein the blades are inclined at a constant angle of 7 to 9 degrees relative to the axis of the fan.

5. 3. The plug fan according to claim 2, wherein the side plate side of the blade plate is located radially outward of the main plate side in the fan radial direction, and the inner diameter of the blade on the main plate side at opposing positions in the blade blade blade blade span direction from the main plate to the side plate is smaller than the inner diameter of the blade on the side plate side.

6. 2. The plug fan according to claim 1, wherein the blades are flat in the blade span direction from the main plate to the side plate, and curved in the blade chord direction from the leading edge to the trailing edge, curving forward in the fan rotation direction, and have a pick-up portion on the leading edge side of the blade that is warped radially outward from the camber line of the blade.

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