JP3629690B2 - Multi-blade blower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
[0002]
The present invention relates to a multiblade fan, and more specifically, a plurality of blades inclined forward are provided between a disk-shaped main plate connected to a drive source and a ring-shaped side plate facing the outer peripheral portion of the main plate. The present invention relates to a multiblade fan equipped with an impeller.
[Prior art]
[0003]
The multi-blade fan which is well known in the art, faces the outer peripheral portion of Figure 1 1 and Figure 1, as shown in 2, disk-shaped main plate 4 and the main plate 4 that is coupled to the fan motor 3 as a drive source The blade-shaped side plate 5 is composed of an impeller 1 having a plurality of blades 6, 6... Inclined forward and a scroll-type fan casing 2 that encloses the impeller 1. In the case of each blade 6 in the impeller 1, the entrance angle β ₁ and the exit angle β ₂ are both the same on the main plate 4 side and the side plate 5 side. Reference numeral 7 denotes a bell mouth attached to the suction side of the fan casing 2 (see, for example, JP-A-7-224788).
[Problems to be solved by the invention]
[0004]
By the way, the basic shape of the blade 6 in the multi-blade fan having the above-described configuration has been experimentally pursued, and has the optimum shape and specifications (for example, the inner and outer diameters of the blade) for the air volume range (for example, the medium air volume area and the large air volume area) to be used. Ratio, number of blades, blade inlet angle, blade outlet angle, etc.) have been sought.
[0005]
For example, in the case of a multi-blade fan used in a medium air volume region, even if the outlet angle β ₂ is increased from a small average inlet wind speed, the blade surface pressure does not increase excessively, so the outlet angle β ₂ = 160 to 170 ° It is set to improve performance. On the other hand, in the case of the multi-blade fan for use in large volume range, blade surface pressure increase by increasing the outlet angle beta ₂ from where the average inlet air velocity is large becomes excessive, the outlet angle beta ₂ because peeling occurs performance deteriorates A small value (β ₂ = 145 to 155 °) is set to ensure good performance.
[0006]
However, the blade outlet angle setting as described above, have been performed as of the average wind speed of the blade inlet, the impeller of the actual multi-blade fan, as shown in FIG. 1 1, the wind speed distribution of the blade inlet F is not uniform and is large on the main plate 4 side and small on the side plate 5 side. Therefore, even if the optimum setting as described above is performed, the total pressure rise in the entire blade surface becomes non-uniform, which may cause performance deterioration and increase in operation sound.
[0007]
Considering the shape of the blade leading edge, by setting the blade inlet angle and the number of blades optimally, the separation vortex generated at the blade leading edge works effectively and does not separate at the latter half of the blade suction surface. Although it becomes a flow state and good performance is obtained, there is concern about the phenomenon that the pressure fluctuation caused by the presence of the leading edge separation vortex interferes with the boundary layer and the wake of the suction surface and increases the operating noise .
[0008]
The present invention has been made in view of the above points, and aims to make uniform the increase in the blade surface total pressure and to reduce the separation vortex at the blade leading edge.
[Means for Solving the Problems]
[0009]
In the first basic configuration of the present invention, as means for solving the above-described problems, a disk-shaped main plate 4 connected to a drive source and a ring-shaped side plate 5 facing the outer peripheral portion of the main plate 4 are provided. In the multiblade fan provided with the impeller 1 formed by standing up a plurality of blades 6, 6... Inclined forward, each of the blades 6 is smoothly negatively projected in the counter-rotating direction of the impeller 1. a pressure surface 6a configured and equivalent point on the main plate side end portion 6b and the side plate side end portion 6c of the respective wings 6 a to e and to E 'to on line I ₁ ~I ₅ connecting each When the blade shape is such that there is a blade surface, and the exit angles on the main plate 4 side and the side plate 5 side in each blade 6 are β ₂ h and β ₂ t, respectively, β ₂ h <β ₂ t Even if the blade inlet velocity distribution F is not uniform, it corresponds to the blade inlet velocity distribution F. Since the blade exit angle can be set, the total pressure rise can be made uniform from the main plate 4 side to the side plate 5 side of the blade 6 while ensuring as much airflow as possible. Yes. That is, as shown in FIGS. 5A and 5B, when the velocity triangles on the blade side plate side and the blade main plate side are analyzed, the swirl components Cu ₂ t, Cu ₂ h becomes almost equal. Therefore, the total pressure increase ΔPt = (γ / g) (u ₂ Cu ₂ t) on the side plate side is almost equal to the total pressure increase ΔPh = (γ / g) (u ₂ Cu ₂ h) on the main plate side. .
[0010]
In the first basic configuration of the present invention, each blade 6 is configured to have a smooth suction surface 6a that is convex in the counter-rotating direction of the impeller 1, and a center line O is formed at the front edge thereof. When the circular arc portion 8 inclined in the rotation direction of the impeller 1 is formed toward the inlet end of the blade 6, or the hollow flow path 9 in which the rear edge side of the blade 6 is opened is formed in each blade 6. In addition, when the suction opening 10 communicating with the hollow flow path 9 is formed only on the suction surface 6a on the inlet side of each blade 6, the blade surface total pressure rise is made uniform and the separation vortex generated at the blade leading edge is generated. It can be reduced, which greatly contributes to driving noise reduction.
DETAILED DESCRIPTION OF THE INVENTION
[0011]
Hereinafter, some preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
First Embodiment FIGS. 1 and 2 show a multiblade blower according to a first embodiment of the present invention.
[0013]
This multiblade fan has the same configuration as already described in the section of the prior art.
[0014]
That is, this multiblade blower has a plurality of blades inclined forwardly between a disk-shaped main plate 4 connected to a fan motor 3 as a drive source and a ring-shaped side plate 5 facing the outer peripheral portion of the main plate 4. Are constituted by an impeller 1 standing up and down, and a scroll type fan casing 2 enclosing the impeller 1. Reference numeral 7 denotes a bell mouth attached to the suction side of the fan casing 2, and each blade 6 has a smooth negative pressure surface 6 a that protrudes in the counter-rotating direction of the impeller 1, as shown in FIGS. 3 and 4. And the blade surface on line segments I ₁ to I ₅ connecting the equivalent points a to e and a ′ to e ′ on the main plate side end 6 b and the side plate side end 6 c of the blade 6, respectively. It is made into a blade shape that exists. When the exit angles of the blades 6 on the main plate 4 side and the side plate 5 side are β ₂ h and β ₂ t, respectively, β ₂ h <β ₂ t is set.
[0015]
When configured as described above, as shown in FIG. 1, the conventional multiblade fan (blade inlet angle β ₁ = 90 °, blade outlet angle β ₂ = 155 °) and the present embodiment will be described next. When a multiblade fan (blade inlet angle β ₁ = 90 °, main plate side blade outlet angle β ₂ h = 145 °, side plate side blade outlet angle β ₂ t = 165 °) was tested for operation, the results shown in FIG. 6 were obtained. Obtained. Here, the impellers of both the multiblade fans were operated with an outer diameter of 250 mm, an axial length of 130 mm, and a rotational speed of 1000 rpm.
[0016]
According to the above result, in the present invention, the specific noise is reduced and the static pressure is also increased. This is nothing but the effect of the uniform increase in the total pressure from the main plate 4 side to the side plate 5 side in the blade 6.
[0017]
Second Embodiment FIG. 7 shows a part of an impeller in a multiblade blower according to a second embodiment of the present invention.
[0018]
In this case, the front edge of each blade 6 in the impeller 1 is formed with an arc portion 8 whose center line O is inclined in the rotational direction M of the impeller 1 toward the blade inlet end. The circular arc portion 8 is formed by forming the blade 6 with a thin plate member and curling its front edge toward the rotation direction M of the impeller 1. When the exit angles of the blade 6 on the main plate 4 side and the side plate 5 side are β ₂ h and β ₂ t , respectively , β ₂ h <β ₂ t is set. Since other configurations are the same as those in the first embodiment, description thereof is omitted.
[0019]
If comprised in this way, since the air flow W which flows toward the circular arc part 8 in the front edge of the blade | wing 6 will flow along the circular arc part 8 by a Counder effect, the peeling which generate | occur | produces in the front edge of the blade negative pressure surface 6a The vortex E is greatly suppressed. Therefore, driving noise is reduced.
[0020]
Next, a conventional multiblade fan having no arc portion (blade inlet angle β ₁ = 90 °, blade outlet angle β ₂ = 155 °) and the multiblade fan according to this embodiment (arc portion center line angle θ) = 80 °, main plate side blade outlet angle β ₂ h = side plate side blade outlet angle β ₂ t = 155 °), the result shown in Fig. 8 was obtained. Here, the impellers of both the multiblade fans were operated with an outer diameter of 250 mm, an axial length of 130 mm, and a rotational speed of 1000 rpm.
[0021]
According to the above results, in the present invention, the increase in static pressure is almost the same, but the specific noise is reduced. This is nothing but the effect of greatly suppressing the separation vortex E generated at the leading edge of the blade suction surface 6a.
Further, since β ₂ h <β ₂ t is set, as described in the first embodiment, the total pressure increase from the main plate 4 side to the side plate 5 side in the blade 6 becomes uniform. The reduction in driving noise is further increased, and the increase in static pressure is also increased.
[0022]
Incidentally, the circular arc portion 8, when formed by curling the leading edge of the blades 6 in the counter-rotational direction of the impeller 1, the outer circumference of the solid of the bulge portion formed on the front edge of the blades 6 when forming the surface, there is a case such as to form a by the outer peripheral surface of the hollow bulge is formed on the front edge of the blades 6.
[0023]
Third Embodiment FIG. 9 shows a part of an impeller in a multiblade blower according to a third embodiment of the present invention.
[0024]
In this case, each blade 6 in the impeller 1 is formed with a hollow passage 9 where the rear edge of the blade 6 is opened, only the negative pressure surface 6a at the inlet side of each blade 6, the hollow flow A suction opening 10 having a slit shape (for example, a slit shape having a width of 0.5 mm) communicating with the passage 9 is formed. The hollow flow path 9 is formed in the blade 6 having a double structure by bending a thin plate member. The position of the suction opening 10 is preferably about 2.0 mm from the front edge of the blade 6. Reference numeral 11 denotes a blowout opening formed at the rear edge of the blade 6. Similarly to the second embodiment described above, the arcuate portion 8 whose center line O is inclined in the rotational direction M of the impeller 1 toward the blade inlet end at the front edge of each blade 6. Is formed. When the exit angles of the blade 6 on the main plate 4 side and the side plate 5 side are β ₂ h and β ₂ t, respectively, β ₂ h <β ₂ t is set. Since other configurations are the same as those in the first embodiment, description thereof is omitted.
[0025]
By configuring as described above, the separation vortex generated on the suction surface 6a at the front edge of the blade 6 is sucked into the hollow flow path 9 from the suction opening 10, and the operation noise is greatly reduced.
[0026]
Next, a conventional multiblade fan (without the hollow flow path 9, the suction opening 10 and the blowout opening 11) and the multiblade fan according to the present embodiment (main plate side blade outlet angle β ₂ h = side plate side blade) was operated experimentally exit angle β ₂ t), the results shown in FIG. 1 0 was obtained. Here, the impellers of both the multiblade fans were operated with an outer diameter of 250 mm, an axial length of 130 mm, and a rotational speed of 1000 rpm.
[0027]
According to the above results, in the present invention, although the static pressure is reduced, the specific noise is greatly reduced. This is nothing but the effect of the separation vortex generated on the suction surface 6 a at the leading edge of the blade 6 being sucked into the hollow flow path 9 from the suction opening 10.
[0028]
Further, since β ₂ h <β ₂ t is set, as described in the first embodiment, the total pressure increase from the main plate 4 side to the side plate 5 side in the blade 6 becomes uniform. The reduction in driving noise is further increased, and the increase in static pressure is also increased.
【The invention's effect】
[0029]
According to the first basic configuration of the present invention, each blade 6 of the impeller 1 in the multiblade fan is configured to have a smooth suction surface 6a that is convex in the counter-rotating direction of the impeller 1 and A blade whose blade surface exists on line segments I _{1 to} I ₅ connecting the equivalent points a to e and a ′ to e ′ on the main plate side end 6 b and the side plate side end 6 c of each blade 6. In addition, when the exit angles of the blades 6 on the main plate 4 side and the side plate 5 side are β ₂ h and β ₂ t, respectively, β ₂ h <β ₂ t is set, and the blade inlet velocity distribution F Since the blade outlet angle corresponding to the blade inlet velocity distribution F can be set even when the blade is non-uniform, the blade 6 moves from the main plate 4 side to the side plate 5 side while ensuring as much airflow as possible. Therefore, the total pressure rise can be made uniform. As shown in (b), when the velocity triangles on the blade side plate side and the blade main plate side are analyzed, the swirl components Cu ₂ t and Cu ₂ h of the blown air flow at the side plate side blade outlet and the main plate side blade outlet are substantially equal. The total pressure increase ΔPt = (γ / g) (u ₂ Cu ₂ t) on the side and the total pressure increase ΔPh = (γ / g) (u ₂ Cu ₂ h) on the main plate side are substantially equal, and the static pressure increase As well as the effect of reducing driving noise while ensuring the required air volume.
[0030]
In the first basic configuration of the present invention, each blade 6 is configured to have a smooth suction surface 6a that is convex in the counter-rotating direction of the impeller 1, and a center line O is formed at the front edge thereof. When the circular arc portion 8 inclined in the rotation direction of the impeller 1 is formed toward the inlet end of the blade 6, or the hollow flow path 9 in which the rear edge side of the blade 6 is opened is formed in each blade 6. In addition, when the suction opening 10 communicating with the hollow flow path 9 is formed only on the suction surface 6a on the inlet side of each blade 6, the blade surface total pressure rise is made uniform and the separation vortex generated at the blade leading edge is generated. It can be reduced, which greatly contributes to driving noise reduction.
[Brief description of the drawings]
[0031]
FIG. 1 is a longitudinal sectional view of a multiblade blower according to a first embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is an enlarged perspective view of blades in the multiblade fan according to the first embodiment of the present invention.
FIG. 4 is an enlarged cross-sectional view showing a part of an impeller in the multiblade blower according to the first embodiment of the present invention.
FIGS. 5A and 5B are speed triangles at a blade outlet in the multiblade fan according to the first embodiment of the present invention. FIG. 5A shows a speed triangle on the side plate side, and FIG. 5B shows a speed triangle on the main plate side.
FIG. 6 is a characteristic diagram comparing the performances of the multiblade fan according to the first embodiment of the present invention and a conventional multiblade fan.
FIG. 7 is an enlarged sectional view showing a part of an impeller in a multiblade blower according to a second embodiment of the present invention.
FIG. 8 is a characteristic diagram comparing the performance of a multiblade fan according to a second embodiment of the present invention (where main plate side blade outlet angle = side plate side blade outlet angle) and a conventional multiblade fan.
FIG. 9 is an enlarged cross-sectional view showing another example of the blades constituting the impeller in the multiblade fan according to the third embodiment of the present invention.
FIG. 10 is a characteristic diagram comparing the performance of a multiblade fan according to a third embodiment of the present invention (where main plate side blade outlet angle = side plate side blade outlet angle) and a conventional multiblade fan.
11 is a Figure 12 XI I- XI I cross-sectional view of FIG. 1 1 is a longitudinal sectional view of a conventional multi-blade fan.
[Explanation of symbols]
[0032]
1 is an impeller, 3 is a drive source (fan motor), 4 is a main plate, 5 is a side plate, 6 is a blade, 6a is a negative pressure surface, 6b is a main plate side end, 6c is a side plate side end, 8 is an arc portion, 9 is a hollow flow path, 10 is a suction opening, 11 is a blow-off opening, O is a center line , a to e are main plate side equivalent points, a 'to e' are side plate side equivalent points, and I _{1 to} I ₅ are line segments .

Claims (3)

A plurality of blades (6), (6) inclined forwardly between a disc-shaped main plate (4) connected to the drive source and a ring-shaped side plate (5) facing the outer peripheral portion of the main plate (4) .. A multi-blade fan provided with an impeller (1) standing upright, wherein each of the blades (6) is a smooth suction surface that is convex in the counter-rotating direction of the impeller (1) ( 6a) and equivalent points (a) to (e) and (a ') to (e) on the main plate side end portion (6b) and the side plate side end portion (6c) of each blade (6). ′) Are formed in a blade shape such that the blade surface exists on the line segments (I ₁ ) to (I ₅ ), and the main plate (4) side and the side plate (5) in each of the blades (6). A multiblade blower characterized in that β ₂ h <β ₂ t is set where β ₂ h and β ₂ t are the outlet angles on the side. Each blade (6) is configured to have a smooth suction surface (6a) that is convex in the counter-rotating direction of the impeller (1), and its center line (O) is at the front edge. The multiblade fan according to claim 1, wherein an arc portion (8) inclined in the rotational direction of the impeller (1) is formed toward an inlet end of (6). In each of the blades (6), a hollow channel (9) in which the rear edge side of the blade (6) is opened is formed, and only on the suction surface (6a) on the inlet side of each blade (6), multiblade blower of claim 1 Symbol mounting, characterized in that the formation of the suction opening (10) communicating with said hollow passage (9).

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