JP7312934B2 - turbo fan - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a turbofan that inflows gas from the direction of its rotation axis and blows out gas in the circumferential direction.

Conventionally, as shown in FIG. 15, this type of turbofan 100 has a bulging portion 101 centered on the rotation axis O, a circular main plate 102 connected to the bulging portion 101, a plurality of blades 104 arranged on the main plate 102 around the bulging portion 101 and provided with wavy projections 103 including a plurality of projections on the front edge, and the plurality of blades 104 connected to the main plate 102 at positions facing each other to suck the air. There is a shroud 105 having an inlet 105a (see, for example, Patent Document 1).

FIG. 16 shows a partial cross-sectional view of the conventional turbofan described in the publication, taken along line XX' of FIG. As shown in FIG. 16, the wavy protrusions 103 including a plurality of protrusions are arranged at smaller pitches toward the main plate 102 side, and the wavy protrusions 103 reduce the scale of the separation vortex W generated when the air flow F flowing from the suction port 105a is bent in the circumferential direction before flowing into the blade 104, thereby reducing noise.

WO2016/067409

Generally, in this type of turbofan 100, the blade length of the blade 104 in the cross section perpendicular to the rotation axis O is adjusted according to the flow velocity flowing into each cross section of the blade 104, and the separation of the airflow at the trailing edge of the blade 104 is suppressed, thereby reducing noise.

However, in the above-described conventional configuration, for example, even on the side of the main plate 102 where the flow velocity of the air is the fastest, the provision of the wavy projections 103 causes some portions where the blade length is not optimized, and the trailing edge of the blade 104 has a problem that airflow separation occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a turbofan that can reduce the scale of the separation vortex and suppress the separation of the airflow at the trailing edge of the blade to reduce the noise without changing the blade length.

In order to solve the above conventional problems, the turbofan of the present invention includes: a bulging portion in the center serving as the center of rotation; a circular main plate connected to the bulging portion; a plurality of blades arranged on the main plate around the bulging portion; and a front edge connecting the negative pressure surface, and a plurality of protrusions are provided at least partly in the axial direction from the front edge to the negative pressure surface.

This causes the airflow to collide with the multiple protrusions to generate small vortices. Therefore, the separation vortex generated at the leading edge when the airflow flowing in from the shroud is bent in the circumferential direction before flowing into the blade collides with the plurality of projections from the leading edge to the suction surface, thereby collapsing the separation vortex and reducing the scale. Furthermore, by providing a protrusion on the suction surface from the leading edge of the conventional blade, the scale of the separation vortex can be reduced without changing the blade length. In general, airflow separation at the leading edge affects the suction surface, but by providing multiple protrusions across the suction surface, small scale vortices collapsed by the protrusions on the leading edge are guided to the suction surface along the protrusions, thereby suppressing separation on the suction surface.

The turbofan of the present invention can reduce the scale of the separation vortex generated when the airflow that flows in from the shroud is bent in the circumferential direction before flowing into the blades, without changing the blade length, and suppresses separation at the trailing edges of the blades, thereby reducing noise.

1 is an external perspective view of a ceiling-embedded air conditioner equipped with a turbofan according to a first embodiment of the present invention; FIG. 1 is a cross-sectional view along A-A' in FIG. 1 is a perspective view of a turbofan according to a first embodiment of the present invention; FIG. 1 is a perspective view of blades mounted on a turbofan according to a first embodiment of the present invention; FIG. 4 of the blades mounted on the turbofan according to the first embodiment of the present invention; FIG. FIG. 4 is a partially enlarged front view of the front edge of the blade mounted on the turbofan according to the first embodiment of the present invention, viewed from the viewpoint S in FIG. FIG. 3 is a cross-sectional view of the turbofan according to the first embodiment of the present invention taken along the line B-B' in FIG. Air volume-noise characteristic diagram of turbo fan in the first embodiment of the present invention The perspective view of the turbofan in the 2nd Embodiment of this invention FIG. 2 is a perspective view of blades mounted on a turbofan according to a second embodiment of the present invention; 10 of the blades mounted on the turbofan according to the second embodiment of the present invention; FIG. FIG. 10 is a partially enlarged front view of the front edge of the blade mounted on the turbofan according to the second embodiment of the present invention, viewed from the viewpoint T in FIG. EE' cross-sectional view in FIG. 9 of the turbofan according to the second embodiment of the present invention (a) Air volume-noise characteristic diagram of the turbo fan in the second embodiment of the present invention (b) Noise frequency characteristic diagram at maximum air volume Perspective view of conventional turbofan XX' cross-sectional view in FIG. 15 of a conventional turbofan

A first aspect of the invention comprises a bulging portion in the center serving as the center of rotation, a circular main plate connected to the bulging portion, a plurality of blades arranged on the main plate around the bulging portion, and a shroud in which the plurality of blades are connected to the main plate at opposing positions. A plurality of protrusions are provided at least partially in the axial direction from the front edge to the negative pressure surface.

This causes the airflow to collide with the multiple protrusions to generate small vortices. Therefore, the separation vortex generated at the leading edge when the airflow flowing in from the shroud is bent in the circumferential direction before flowing into the blade collides with the plurality of projections from the leading edge to the suction surface, thereby collapsing the separation vortex and reducing the scale. Furthermore, by providing a protrusion on the suction surface from the leading edge of the conventional blade, the scale of the separation vortex can be reduced without changing the blade length. In general, airflow separation at the leading edge affects the suction surface, but by providing multiple protrusions across the suction surface, small scale vortices collapsed by the protrusions on the leading edge are guided to the suction surface along the protrusions, thereby suppressing separation on the suction surface. Therefore, with respect to the separation vortex generated when the airflow flowing in from the shroud is bent in the circumferential direction before flowing into the blade, the scale of the separation vortex can be reduced without changing the blade length, and separation at the trailing edge of the blade can be suppressed, thereby reducing noise.

According to a second aspect of the invention, the plurality of projections have a front view shape of a connecting portion between the front edge portion and the negative pressure surface that is substantially an ellipse with a major axis in the flow direction.

As a result, the scale of the vortex generated when colliding with the protrusion is smaller than that of a circular shape. Therefore, even in the case of a low air flow rate, where separation vortices tend to occur especially near the leading edge, the separation vortices can be reliably collapsed to reduce the scale. Therefore, even when the amount of air is low, especially when the separation vortex tends to occur near the leading edge, the scale of the separation vortex can be reduced, and the noise can be reduced.

In a third aspect of the invention, the plurality of projections have larger projections as they approach the shroud.

The separation vortex becomes large on the shroud side where the air flow entering from the shroud bends in the circumferential direction before flowing into the blades, where the bend is sharp. Therefore, by enlarging the projection on the shroud side, even a large separation vortex is collapsed and the scale is reduced. Therefore, even at the maximum air volume when the separation vortex generated when the airflow flowing from the shroud is bent in the circumferential direction before flowing into the blades becomes particularly large, the scale of the separation vortex can be reduced to reduce noise. In addition, by making the size of the protrusions non-uniform, the scale of the vortex when the separation vortex collapses becomes non-uniform, and the frequency of the sound caused by this vortex becomes non-uniform. Therefore, by making the sizes of the projections non-uniform, the frequency of the sound caused by the separation vortex becomes non-uniform, and the noise can be further reduced.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 shows an external perspective view of a ceiling-embedded air conditioner equipped with a turbofan according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA' in FIG. 1 of the ceiling-embedded air conditioner equipped with the turbofan according to the first embodiment of the present invention. FIG. 3 shows a perspective view of the turbofan in the first embodiment of the invention. FIG. 4 is a perspective view of blades mounted on the turbofan according to the first embodiment of the invention. FIG. 5 is a partial enlarged view of the DD' section in FIG. 4 of the blades mounted on the turbofan according to the first embodiment of the present invention. FIG. 6 is a partially enlarged front view of the front edge of the blade mounted on the turbofan according to the first embodiment of the present invention, viewed from the viewpoint S in FIG.

First, the configuration of a ceiling-embedded air conditioner equipped with a turbofan according to the first embodiment will be described.

In FIG. 1, the ceiling-embedded air conditioner 1 is composed of a housing 2 and a decorative panel 6 provided on the bottom surface of the housing 2 and having a plurality of outlets 3, an intake grille 4, and a wind deflector 5.

2, the interior of the ceiling-embedded air conditioner 1 includes a turbo fan 7, a motor 8 for driving the turbo fan 7, an intake grill 4 composed of a grill 4a and a filter 4b, an orifice 9 for inducing an airflow F flowing from the intake grill 4 to the turbo fan 7, a heat exchanger 10 arranged to surround the turbo fan 7, and a drain pan 1 supporting the heat exchanger 10 and forming a part of the internal air passage 3a of the outlet 3 on the housing 2 side. 1 and an internal heat insulating material 12 disposed on the inner surface of the housing 2 and forming a part of the internal air passage 3a of the air outlet 3. As shown in FIG. The ceiling-embedded air conditioner 1 is installed in a concave portion of the ceiling 50 by being suspended by suspension bolts 51 .

Next, the configuration of the turbofan will be described. In FIG. 3, the turbo fan 7 has a bulge portion 13 centered on a rotation axis O, a boss portion 13a to which the shaft of the motor 8 is connected, a circular main plate 14 connected to the bulge portion 13, a plurality of blades 15 arranged on the main plate 14 around the bulge portion 13, a plurality of blades 15, and an annular bell shape having a suction port 16a in the center and having a suction port 16a in the center. and a shroud 16 with a The blade 15 is formed of a pressure surface 15a that is the front surface with respect to the rotation direction C, a suction surface 15b that is the rear surface with respect to the rotation direction C, a front edge portion 15c that connects the pressure surface 15a and the suction surface 15b on the bulging portion 13 side, a connection portion 15d between the pressure surface 15a and the front edge portion 15c, and a connection portion 15e between the suction surface 15b and the front edge portion 15c.

Further, as shown in FIGS. 4, 5, and 6, the blade 15 has a pressure surface 15a and a suction surface 15b which are curved surfaces, and when viewed from the front edge portion 15c side, the front edge portion 15c is curved in the axial direction to form a three-dimensional blade 15. A plurality of protrusions 17 are provided in the axial direction from the front edge portion 15c to the suction surface 15b so that the flow direction of the airflow is the major axis, and are provided so as not to overlap the connecting portion 15d between the pressure surface 15a and the front edge portion 15c. The blade 15 is a member made of resin for weight reduction.

The operation and effects of the turbofan configured as described above will be described below. First, the operation of the air conditioner 1 will be described. In FIG. 2, when the turbofan 7 rotates in direction C, the airflow F flows into the air conditioner 1 from the grille 4a and the filter 4b, is rectified by the orifice 9, and is led to the turbofan 7. As shown in FIG. Then, the air is blown out radially from the outer periphery of the turbo fan 7, cooled or heated to a predetermined temperature when passing through the heat exchanger 10, and directed in a predetermined direction by the air deflector 5 from the outlet 3 to flow out.

A part of the airflow F does not pass through the heat exchanger 10 and becomes a cooling airflow F1 that takes heat from the motor 8 and a circulating airflow F2 that short-circuits from the outer circumference of the orifice 9 and flows into the turbo fan 7 again, and joins the airflow F in the turbofan 7. - 特許庁

Next, the flow of the airflow F passing through the turbofan 7 will be described. FIG. 7 is a cross-sectional view of the turbofan taken along the line BB' in FIG. 3 according to the first embodiment of the present invention. In FIG. 7, the airflow F flows into the turbofan 7 from the suction port 16a in the axial direction, is bent in the circumferential direction near the blades 15, and is blown out from the turbofan 7. As shown in FIG. At that time, a separation vortex W is generated in the vicinity of the front edge portion 15c due to the collision of the airflow F with the bend and the front edge portion 15c, and the separation vortex W is generated on the side of the suction surface 15b, which is the rear surface in the rotation direction C, and the flow of the airflow F on the suction surface is disturbed. Therefore, the projection 1 extends from the front edge portion 15c to the negative pressure surface 15b.
7, when the separation vortex W generated in the vicinity of the front edge portion 15c collides with the projection 17, the separation vortex W is collapsed to reduce the scale.

Further, by providing a protrusion from the front edge portion 15c of the conventional blade 15 to the negative pressure surface 15b, the scale of the separation vortex W can be reduced without changing the blade length.

As described above, in this embodiment, by providing a plurality of projections 17 from the front edge 15c of the blade 15 to the negative pressure surface 15b, the airflow collides with the plurality of projections 17 to generate small eddies. Therefore, the separation vortex W generated at the leading edge portion 15c when the airflow flowing in from the suction port 16a is bent in the circumferential direction before flowing into the blade 15 collides with the plurality of projections 17 extending from the leading edge portion 15c to the negative pressure surface 15b, thereby collapsing the separation vortex W and reducing the scale. Furthermore, by providing the protrusion 17 from the front edge 15c of the conventional blade 15 to the negative pressure surface 15b, the scale of the separation vortex W can be reduced without changing the blade length. In general, separation of the airflow F at the front edge 15c affects the suction surface 15b, but by providing a plurality of projections 17 over the suction surface 15b, small-scale vortices collapsed by the projections 17 provided on the front edge 15c are guided to the suction surface 15b along the projections 17, thereby suppressing separation on the suction surface 15b. Therefore, the scale of the separation vortex W generated when the airflow flowing from the suction port 16a is bent in the circumferential direction before flowing into the blade 15 can be reduced by reducing the scale of the separation vortex W without changing the blade length, thereby reducing noise.
Moreover, noise can be reduced by reducing the scale of flaking on the negative pressure surface 15b, which tends to be affected by flaking on the front edge portion 15c.

FIG. 8 shows the air volume-noise characteristic diagram of the turbofan in the first embodiment of the present invention. As shown in FIG. 8, in the present embodiment, the higher the air flow rate, the greater the difference in noise value compared to the turbo fan without the projections 17 . That is, the higher the air volume, the smaller the noise value.

Further, since the separation vortex W generated in the vicinity of the front edge portion 15c is caused by the bending of the fluid, if the theory of bending inside the pipe is applied, the scale will be about W=0.01d to 0.05d at the flow velocity of the airflow F in the present embodiment with respect to the flow path width d of the airflow F shown in FIG.

Therefore, the size of the protrusion 17 in the present embodiment is preferably about the same as the scale of the separation vortex W, and the front view shape of the connecting portion between the front edge portion 15c and the suction surface 15b is approximately an ellipse whose major axis is the flow direction, and with respect to the blade length L shown in FIG. It is configured such that D2>h.

Further, by setting the distance P between the projections 17 in the axial direction to 0.1H to 0.3H with respect to the blade height H, the noise of the turbo fan 7 can be minimized.

In addition, in the present embodiment, the shape of the protrusion 17 is substantially elliptical with the major axis in the flow direction, so that the scale of the separation vortex W generated when colliding with the protrusion 17 is smaller than in a circular shape. Therefore, even in the case of a low air flow, which tends to generate the separation vortex W especially near the front edge portion 15c, the separation vortex W can be reliably collapsed to reduce the scale.

Therefore, even when the flow rate of the separated vortex W is particularly likely to occur in the vicinity of the leading edge portion 15c, the scale of the separated vortex W is reduced, and the noise can be reduced.

In addition, by making the interval P between the protrusions 17 of the present embodiment unequal, the period when the separation vortex W is collapsed to reduce the scale becomes uneven in the axial height, and the noise can be reduced by suppressing the noise peak in a specific frequency band.

In the present embodiment, the number of projections 17 is three, but the number of projections 17 is not particularly limited as long as the distance P between the projections 17 is maintained.

(Embodiment 2)
FIG. 9 shows a perspective view of a turbofan according to a second embodiment of the invention. FIG. 10 is a perspective view of blades mounted on a turbofan according to the second embodiment of the invention. FIG. 11 is a partially enlarged view of the FF' section in FIG. 10 of the blades mounted on the turbofan according to the second embodiment of the present invention. FIG. 12 is a partially enlarged front view of the front edge portion of the blade mounted on the turbofan according to the second embodiment of the present invention, viewed from the viewpoint T in FIG. Parts that are the same as or correspond to those in the first embodiment are denoted by the same reference numerals, and part of the description is omitted.

9, 10, 11, and 12, projections 18a, 18b, and 18c are provided in the axial direction from the front edge 15c of the blade 15 to the suction surface 15b so as not to interfere with the connecting portion 15d between the pressure surface 15a and the front edge 15c so that the airflow direction is the major axis. The sizes of the projections 18a, 18b, 18c increase as they approach the suction port 16a.

The operation and effects of the turbofan configured as described above will be described below. FIG. 13 is a cross-sectional view of the turbofan taken along line EE' in FIG. 9 in accordance with the second embodiment of the present invention. In FIG. 13 , the airflow F flows into the turbofan 7 from the suction port 16 a in the axial direction, is bent in the circumferential direction near the blades 15 , and is blown out from the turbofan 7 . At that time, a separation vortex W is generated in the vicinity of the front edge portion 15c due to the collision of the airflow F with the bend and the front edge portion 15c, and the separation vortex W is generated on the side of the suction surface 15b, which is the rear surface in the rotation direction C, and the flow of the airflow W on the suction surface is disturbed. Especially when the air volume is maximum, the curve of the airflow F near the front edge 15c becomes steeper as it approaches the shroud 16, so the scale of the separation vortex W becomes larger as it approaches the suction port 16a (Wa>Wb>Wc). Therefore, by providing the projections 18 different in size from the projections 18a to 18c from the front edge 15c to the negative pressure surface 15b, when the separation vortices Wa to Wc generated in the vicinity of the front edge 15c collide with the projections 18a to 18c, the separation vortices W having different scales are reliably collapsed to reduce the scale.
Furthermore, by providing a protrusion from the front edge 15c of the conventional blade to the suction surface 15b, the scale of the separation vortices Wa to Wc can be reduced without changing the blade length.

As described above, in the present embodiment, by providing a plurality of projections 18a to 18c of different sizes from the front edge 15c of the blade 15 to the negative pressure surface 15b, the airflow collides with the plurality of projections 18 to generate small eddies. Therefore, when the airflow flowing in from the suction port 16a is bent in the circumferential direction before flowing into the blade 15, the separation vortices Wa to Wc generated at the front edge 15c collide with the projections 18a to 18c of different sizes extending from the front edge 15c to the negative pressure surface 15b. Therefore, even at the maximum air volume when the separation vortex W generated when the airflow flowing from the suction port 16a is bent in the circumferential direction before flowing into the blade 15 becomes particularly large, the scale of the separation vortex W can be reduced to reduce noise. In addition, by making the size of the protrusions 18 non-uniform, the frequency of the sound caused by the separation vortex W becomes non-uniform, and noise can be further reduced.

FIG. 14 shows (a) an air volume-noise characteristic diagram and (b) a noise frequency characteristic diagram at the maximum air volume of the turbo fan according to the second embodiment of the present invention. As shown in FIG. 14(a), in the present embodiment, the higher the air volume, the greater the difference in noise value compared to the turbo fan without projections 18a to 18c. That is, the higher the air volume, the smaller the noise value. Also, as shown in FIG. 14(b), compared to a turbofan with uniform protrusion sizes, in this embodiment, the noise value in the low frequency band (100 Hz to 1 kHz) that relatively affects the overall noise value can be reduced.

Further, since the separation vortex W generated in the vicinity of the front edge portion 15c is caused by the bending of the fluid, applying the theory of the bend in the pipe, the scale is about 0.02d to 0.1d at the separation vortex Wa near the suction port 16a at the flow velocity d of the airflow F in the present embodiment with respect to the flow path width d of the airflow F shown in FIG.

Therefore, the size of the projection 18 in the present embodiment is such that, with respect to the blade length L, the long axis D1 of the projection 18a near the suction port 16a is 0.03L to 0.23L, the short axis D2 is 0.02L to 0.08L, the height h is 0.008L to 0.05L, and the long axis D1 is 0.025L to 0.20L, and the short axis D2 of the projection 18b at approximately the center of the blade height H is 0.025L to 0.20L. 13L to 0.06L, height h of 0.0065L to 0.04L, long axis D1 of projection 18c near main plate 14 is 0.02L to 0.15L, short axis D2 is 0.01L to 0.05L, height h is 0.005L to 0.03L, and projections 18a, 18b, and 18c are all configured to satisfy D1>D2>h.

Further, by setting the interval P between the projections 18 in the axial direction to 0.1H to 0.3H with respect to the blade height H, the noise of the turbo fan 7 can be minimized.

In addition, in the present embodiment, the shape of the protrusion 18 is substantially elliptical with the major axis in the flow direction, so that the scale of the separation vortex W generated when colliding with the protrusion 18 is smaller than in a circular shape.

Therefore, even when the separation vortex W in the vicinity of the leading edge portion 15c tends to affect the trailing edge side of the blade 15, the scale of the separation vortex W can be reduced and the efficiency can be improved.

In addition, by making the interval P between the protrusions 18 of the present embodiment unequal, the period when the separation vortex W is collapsed and the scale is reduced becomes uneven in the axial height, and the noise can be reduced by suppressing the noise peak in a specific frequency band.

In the present embodiment, the number of projections 18 is three, but the number of projections 18 is not particularly limited as long as the distance P between the projections 18 is maintained.

INDUSTRIAL APPLICABILITY As described above, the turbofan according to the present invention can reduce the scale of the separated vortex generated when the airflow flowing from the shroud is bent in the circumferential direction before flowing into the blades, without changing the blade length, and suppress the separation of the airflow at the trailing edge of the blades to reduce noise.

7 turbofan 13 swelling portion 14 main plate 15 blade 15a pressure surface 15b suction surface 15c front edge portion 16 shroud 16a suction port 17 projection 18 projection

Claims (2)

a bulging portion in the center that serves as the center of rotation;
a circular main plate connected to the bulge;
a plurality of blades arranged on the main plate around the bulge;
a shroud in which the plurality of blades are connected to the main plate at positions facing each other;
The blade has a pressure surface that is a front surface with respect to the direction of rotation;
a negative pressure surface that is a rear surface in the direction of rotation;
A front edge portion connecting the pressure surface and the suction surface is formed on the bulging portion side, and a plurality of projections are provided on at least part of the axial direction from the front edge portion to the suction surface,
The turbofan, wherein the plurality of protrusions increase in size as it approaches the shroud side from the main plate side. An indoor unit comprising the turbofan according to claim 1.