JP2014139432A - Centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal fan capable of improving a diffuser effect of converting the kinetic energy of an air flow to pressure by diffuser rings.SOLUTION: A centrifugal fan 23 includes: a hub 15; a plurality of blades 21; and a shroud 19. Each blade 21 includes a curved portion 21d curved so that a connection end 21c connected to an inwardly projecting part of the shroud 19 is inclined toward a side 21c1 on which an air flow strikes when the connection end 21c moves in a rotational direction of the centrifugal fan 23. The hub 15 includes a hub-side diffuser ring 27 protruding to the outer peripheral side of each blade 21. The shroud 19 includes a shroud-side diffuser ring 26 protruding to the outer peripheral side of each blade 21.

Description

  The present invention relates to a centrifugal fan.

  Conventionally, a centrifugal fan such as a turbo fan is used to supply air at a high pressure in an air handling unit or other air conditioner for performing large-scale air conditioning inside a building. The turbo fan is a fan having rearward facing blades, and has a structure in which an air flow is blown outward in the radial direction. Therefore, there is an advantage that the structure is simplified because a scroll casing such as a sirocco fan is not required. However, there is a problem that the airflow from the blade immediately interferes with an object around the blade and disturbs the flow, resulting in an increase in noise and a decrease in efficiency.

  Therefore, conventionally, like the turbofan described in Patent Documents 1 and 2, a hub, a plurality of blades arranged side by side in the circumferential direction of the hub, and the opposite side of the hub with respect to the blades In the configuration including the arranged shroud, a diffuser ring is provided on the outer peripheral side of the blade. In the turbofan described in these Patent Documents 1 and 2, the outer diameters of the shroud and the hub are larger than the outer diameters of the blades, and the diffuser ring is formed by the shroud and the hub located outside the blades. Yes.

  As a result, the airflow coming out of the blades is decelerated while passing between the diffuser rings, and the effect of converting the kinetic energy of the airflow into pressure effectively, the so-called diffuser effect, can improve the efficiency of the fan. Is possible.

  The blades in such a turbofan are usually two-dimensional blades having a uniform cross section perpendicular to the axial direction as they are displaced along the axial direction of the rotational axis of the turbofan. It is connected at an acute angle to the overhanging part.

JP-A-11-108403 US Patent Publication No. 2006/0228212

  In the configuration of the turbofan having a diffuser ring as described in the above-mentioned Patent Documents 1 and 2, as shown in FIG. 13, the axial section of the turbofan (for example, the centrifugal fan 23 shown in FIG. 3). (Cross-section at a position corresponding to the IV-IV line cross-section of FIG. 4), the blade 121 composed of a two-dimensional blade is disposed between the shroud 119 and the hub 115, and the blade 121 and the shroud 119 are connected at an acute angle. In the portion 129, a region 129 in which the airflow is easily disturbed is generated. Due to the turbulence of the airflow, as shown in FIG. 14, on the shroud 119 side, the flow velocity of the airflow F10 flowing into the turbofan from the air inlet 119a is partially reduced. As a result, as the air flow F10 travels along the blades 121 from the air inflow port 119a toward the air outlet 128, a separation region 130 in which the air flow F10 is separated from the inner surface of the shroud 119 may be generated. Therefore, it becomes difficult to improve the diffuser effect by the diffuser rings 126 and 127 provided on the outer periphery of the hub 115 and the shroud 119.

  This invention is made | formed in view of the above situations, and it aims at providing the centrifugal fan which can improve the diffuser effect which converts the kinetic energy of an airflow into a pressure by diffuser ring.

  The centrifugal fan (23) of the present invention includes a hub (15), a plurality of blades (21) arranged in a circumferential direction of the hub (15), and the hub (21) with respect to the blades (21). 15) and a shroud (19) disposed on the opposite side of the centrifugal fan. The blade (21) has a connecting end (21c) connected to a portion projecting inwardly in the shroud (19). (23) has a curved portion (21d) curved so as to incline toward the side (21c1) on which the airflow hits when moved in the rotation direction, and the hub (15) is on the outer peripheral side of the blade (21) The shroud (19) has a shroud side diffuser ring (26) protruding to the outer peripheral side of the blade (21).

  According to such a configuration, the blade (21) is on the side on which the airflow hits when the connecting end (21c) connected to the inwardly projecting portion of the shroud (19) moves in the rotational direction of the centrifugal fan (23). Since the curved portion (21d) is curved so as to be inclined toward the (21c1) side, the portion where the shroud (19) and the blade (21) are connected at an acute angle is eliminated. As a result, the airflow can smoothly flow at the portion where the blade (21) and the shroud (19) are connected, and the region where the airflow is likely to be turbulent can be reduced at that portion. As a result, on the shroud (19) side, it is possible to suppress a decrease in the flow velocity of the airflow due to the turbulence of the airflow, and to prevent a separation area where the airflow peels from the inner surface of the shroud (19). As a result, the diffuser effect for converting the kinetic energy of the airflow into the pressure in the hub (15) side and the shroud side diffuser ring (26), particularly the diffuser effect in the shroud side diffuser ring (26) is improved.

  Further, the hub side end (21e) at the rear edge (21b) of the blade (21) is more forward than the shroud side end (21f) of the rear edge (21b) in the rotational direction of the centrifugal fan (23). It is preferable that it is located in.

  According to this configuration, at the rear edge (21b) of the blade (21), the hub side end portion (21e) is positioned in front of the shroud side end portion (21f) in the rotational direction. ) Is inclined toward the shroud (19) side by the inclination of the blade (21) with respect to the axial direction, and the separation of the airflow on the shroud (19) side can be further suppressed. This also makes the air flow uniform in the axial direction of the centrifugal fan (23), so that the diffuser effect, particularly the shroud side, converts the kinetic energy of the air flow in the hub (15) side and shroud side diffuser ring (26) into pressure. In the diffuser ring (26), the diffuser effect is improved.

  The outer diameter of the hub side diffuser ring (27) and the outer diameter of the shroud side diffuser ring (26) are each 1.1 times or more the diameter of the circumscribed circle of the plurality of blades (21). preferable.

  According to such a configuration, the diffuser effect that converts the kinetic energy of the airflow into the pressure in the hub side diffuser ring (27) and the shroud side diffuser ring (26) can be reliably obtained.

  Preferably, the shroud side diffuser ring (26) further includes a portion (26a) extending linearly in the radial direction of the centrifugal fan (23) continuously to the edge of the shroud (19).

  According to this configuration, the airflow flowing along the inner wall of the shroud (19) can smoothly flow along the linearly extending portion (26a) when reaching the shroud side diffuser ring (26). is there. Therefore, it is possible to suppress separation of the airflow in the shroud side diffuser ring (26).

  The shroud side diffuser ring (26) has a portion bent in the axial direction of the centrifugal fan (23) so as to be separated from the hub side diffuser ring (27), and the hub side diffuser ring (27) It preferably extends in the radial direction of the fan (23).

  According to this configuration, since the shroud side diffuser ring (26) is shaped to expand in the axial direction of the centrifugal fan (23), the airflow between the hub side diffuser ring (27) and the shroud side diffuser ring (26). Can pass more smoothly. Moreover, the hub side diffuser ring (27) does not expand in the axial direction but extends in the radial direction, so that it is possible to form the same plane as the inner part of the hub (15) with respect to the hub side diffuser ring (27). Thus, it is possible to suppress an increase in the processing cost of the hub (15). In addition, since the shroud (19) is conventionally curved, machining can be suppressed by increasing the shape of the shroud side diffuser ring (26) in the axial direction. Accordingly, it is possible to suppress an increase in the processing cost of the entire centrifugal fan (23).

  As described above, according to the present invention, it is possible to improve the diffuser effect of converting the kinetic energy of the airflow into pressure by the hub side diffuser ring and the shroud side diffuser ring.

It is a longitudinal cross-sectional view which shows the inside of the indoor unit of the air conditioner provided with the centrifugal fan concerning embodiment of this invention. It is a perspective view of the centrifugal fan of FIG. It is the figure which looked at the centrifugal fan of FIG. 1 from the air inlet side. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is explanatory drawing which shows typically the flow of the air in the inside of the centrifugal fan of FIG. FIG. 2 is an enlarged view of a portion in the vicinity of a trailing edge of the blade of FIG. 1. It is explanatory drawing which shows each dimension of the hub side diffuser ring and shroud side diffuser ring of the centrifugal fan of FIG. The static pressure efficiency of the centrifugal fan according to the embodiment of the present invention having both the shroud side diffuser ring and the hub side diffuser ring and the static pressure efficiency of the centrifugal fan not having one or both of the diffuser rings are shown side by side. It is a graph. The effect of improving the maximum static pressure efficiency by the diffuser ring in the centrifugal fan having the three-dimensional blades in the embodiment of the present invention, and the improvement of the maximum static pressure efficiency by the diffuser ring in the centrifugal fan having the two-dimensional blades in the comparative example of the present invention. It is the graph which compared the effect of. It is the figure which showed the wind speed distribution near the blower outlet of a centrifugal fan, (a) is the figure which showed the wind speed distribution near the blower outlet of the centrifugal fan which has a three-dimensional blade and diffuser ring in embodiment of this invention, (b) ) Is a diagram showing the wind speed distribution near the outlet of a centrifugal fan having a two-dimensional blade and a diffuser ring in a comparative example of the present invention. It is a section explanatory view showing an example in which a hub side diffuser ring comprises the same plane as a hub in a centrifugal fan concerning a modification of the present invention. It is sectional explanatory drawing which shows the example in which the shroud side diffuser ring has the part extended linearly in the centrifugal fan concerning the modification of this invention. It is sectional drawing of the blade | wing and its peripheral part in the conventional centrifugal fan. It is explanatory drawing which shows typically the flow of the air in the inside of the conventional centrifugal fan.

  Hereinafter, an indoor unit of an air conditioner according to an embodiment of the present invention will be described in detail with reference to the drawings.

  An indoor unit 31 shown in FIG. 1 is a ceiling-embedded cassette indoor unit. The indoor unit 31 includes a substantially rectangular parallelepiped housing 33 embedded in an opening provided in the ceiling C, and a decorative panel 47 attached to the lower portion of the housing 33. The decorative panel 47 is slightly larger in plan view than the housing 33 and is exposed indoors in a state of covering the opening of the ceiling C. The decorative panel 47 has a rectangular suction grill 39 provided at the center thereof, and a plurality of (for example, four) elongated rectangular outlets 37 provided along each side of the suction grill 39. doing.

  The indoor unit 31 includes a blower 51 including a centrifugal fan 23, a fan motor 11 that rotationally drives the centrifugal fan 23, a heat exchanger 43 that surrounds the outside of the centrifugal fan 23, a drain pan 45, and an air filter 41. ing.

  The blower 51 includes a centrifugal fan 23 that is a turbo fan and a bell mouth 25.

  As shown in FIGS. 1 to 3, the centrifugal fan 23 corresponds to the hub 15, a plurality of (seven in FIG. 2 to 3) blades 21 arranged in the circumferential direction of the hub 15, and the blades 21. And a shroud 19 disposed on the opposite side of the hub 15. As shown in FIGS. 2 and 5, the air outlets 28 through which the airflow blows out in the centrifugal fan 23 are formed by spaces surrounded by the hub 15, the shroud 19, and the two blades 21, respectively.

  The hub 15 is fixed to the rotating shaft 13 of the fan motor 11 fixed to the top plate of the housing 33.

  The hub 15 has a hub side diffuser ring 27 that protrudes to the outer peripheral side of the blade 21. Specifically, the hub side diffuser ring 27 has a ring shape and is formed outside the rear edge 21 b of each blade 21.

  The shroud 19 is disposed opposite to the hub 15 on the front side F (see FIG. 1) in the axial direction A of the rotary shaft 13. The shroud 19 has an air suction port 19 a that opens in a circle around the rotation shaft 13. The outer diameter of the shroud 19 increases toward the back side R (see FIG. 1). In other words, as shown in FIGS. 4 to 5, the shroud 19 has a portion 19 b that curves and protrudes inward of the centrifugal fan 23 from the air suction port 19 a to the blowout port 28.

  The shroud 19 has a shroud side diffuser ring 26 that protrudes to the outer peripheral side of the blade 21. The shroud side diffuser ring 26 is formed outside the rear edge 21 b of each blade 21 and is disposed so as to face the hub side diffuser ring 27.

  The mutually facing surfaces of the hub side diffuser ring 27 and the shroud side diffuser ring 26 are smoothly continuous with the mutually facing surfaces of the hub 15 and the shroud 19, respectively.

  In addition, as shown in FIG. 5, the distance between the diffuser rings 27 and 26 is set so as to gradually increase toward the outer periphery of the centrifugal fan 23.

  The plurality of blades 21 are arranged between the hub 15 and the shroud 19 at a predetermined interval along the circumferential direction of the air suction port 19a. An end portion on the front side F (see FIG. 1) of each blade 21 is joined to the inner surface of the shroud 19. The end of each blade 21 on the back side R (see FIG. 1) is joined to the hub 15. As shown in FIG. 3, each blade 21 is inclined so as to go outward in the radial direction toward the opposite direction (backward direction) of the rotation direction B with respect to the radial direction of the hub 15 (that is, the blade shown in FIG. 3). The rear edge 21b of the 21 is a rearward-facing blade (disposed radially outside the front edge 21a).

  Each blade 21 shown in FIGS. 2 to 6 is a blade having a shape in which a cross-sectional shape perpendicular to the axial direction A changes as it is displaced along the axial direction A of the rotating shaft 13 of the motor 11, so-called three-dimensional. It is comprised by the shape blade | wing. In other words, in the blade 21 composed of such a three-dimensional blade, as shown in FIG. 2, the front edge 21a and the rear edge 21b of the blade 21 have a twisted positional relationship, and the blade 21 The end on the front side F and the end on the back side R have a twisted relationship.

  As shown in FIGS. 3 to 5, each blade 21 includes a main portion 21 h joined to the hub 15, a curved portion 21 d continuous to the end portion of the main portion 21 h on the shroud 19 side, and the curved portion 21 d. A connecting end 21c continuous with the end of the shroud side 19; Note that the rotation direction B in FIG. 4 is a direction extending perpendicularly to the near side with respect to the paper surface of FIG.

  The connection end portion 21 c is connected to a portion 19 b projecting inward in the shroud 19. Specifically, the inwardly projecting portion 19b of the shroud 19 is a portion that is curved and projects to the inside of the centrifugal fan 23 as shown in FIG. This is a portion excluding the portion extending in the direction.

  The curved portion 21d is curved so as to incline toward the side 21c1 where the airflow hits when the connecting end portion 21c moves in the rotation direction B of the centrifugal fan 23.

  Specifically, the curved portion 21d is caused to protrude from the main portion 21h to the side opposite to the side 21d1 on which the airflow hits when the portion of the blade 21 closer to the shroud 19 is moved in the rotation direction B. Is formed. The connection end 21c is connected to a portion 19b projecting inward of the shroud 19 so as to be substantially orthogonal to a tangent C (see FIG. 4) of the inner surface of the portion 19b. As shown in FIG. 5, the curved portion 21 d is formed continuously from the front edge 21 a to the rear edge 21 b of the blade 21.

  As a result, as shown in FIGS. 4 to 5, the blade 21 and the shroud 19 are formed on the side 21 c 1 where the air flow hits when the connection end 21 c moves in the rotation direction B in the connection end 21 c of the blade 21. A portion connected to the acute angle is eliminated, and instead, a region 29 (that is, an expanded recess) that is recessed and enlarged in the direction opposite to the side 21c1 on which the airflow hits is formed from the front edge 21a to the rear edge 21b of the blade 21a. The The expansion recess 29 ensures a sufficiently wide air passage. As a result, it is possible to suppress a decrease in the flow velocity of the air flow F0 in the vicinity of the connection end 21c.

  Further, as shown in FIG. 6, the hub side end portion 21e of the rear edge 21b of the blade 21 is located on the front side in the rotational direction B of the centrifugal fan 23 relative to the shroud side end portion 21f of the rear edge 21b. .

  Thus, by positioning the hub side end 21e on the front side in the rotational direction B at the rear edge 21b of the blade 21 as described above, the airflow is inclined as shown by the arrow F1 in FIG. That is, it flows easily to the shroud 19 side by flowing along the rotation direction B side surface). As a result, as shown in FIG. 5, the air flow F0 passing through the inside of the centrifugal fan 23 becomes uniform in the axial direction A of the centrifugal fan 23, whereby the diffuser effect in the pair of diffuser rings 26, 27, that is, the air flow The effect of converting the kinetic energy of F1 into static pressure, particularly the diffuser effect on the shroud 19 side can be improved.

  Further, as shown in FIG. 7, the outer diameter D2 of the hub side diffuser ring 27 and the outer diameter D3 of the shroud side diffuser ring 26 are respectively circumscribed circles of the plurality of blades 21 in order to ensure the above diffuser effect. The diameter D1 is set to 1.1 times or more. In FIG. 7, the outer diameter D2 of the hub-side diffuser ring 27 and the outer diameter D3 of the shroud-side diffuser ring 26 are set to be the same. However, the present invention is not limited to this, The diameters D2 and D3 are not necessarily the same.

  Further, as shown in FIG. 7, the distance H2 between the outlet sides (that is, radially outside) of the pair of diffuser rings 26 and 27 is larger than the height H1 of the outlet side (that is, the trailing edge 21b) of the blade 21. It is set to be. Specifically, the shroud side diffuser ring 26 and the hub side diffuser ring 27 are arranged so as to incline in directions away from each other toward the respective distal ends. Thereby, the air flow F0 can pass between the pair of diffuser rings 26 and 27 more smoothly.

  Since the centrifugal fan 23 configured as described above includes the shroud-side diffuser ring 26 and the hub-side diffuser ring 27, the static pressure efficiency can be greatly improved as compared with a centrifugal fan that does not include these. It is.

  For example, as shown in the graph of FIG. 8, when the horizontal axis represents the flow coefficient φ and the vertical axis represents the static pressure efficiency η, the shroud side diffuser ring 26 and the hub side diffuser ring as in the centrifugal fan 23 of the present embodiment. The static pressure efficiency η in the case of having both 27 can be improved over the entire flow rate count φ as shown in the curve IV over the static pressure efficiency η (curve I) in the case of not having these diffuser rings. Recognize.

  Further, the static pressure efficiency η with only the hub side diffuser ring is improved in the region where the flow coefficient φ is φ <about 0.23 as shown in the curve II, but the flow coefficient φ is φ It tends to not improve in the region of> 0.23. On the other hand, the static pressure efficiency η with only the shroud side diffuser ring is improved in the region where the flow coefficient φ is φ> about 0.15 as shown by the curve III, but the flow coefficient φ is φ It tends to not improve in the region of <0.15.

Compared to the cases of these curves II and III, as shown by the curve IV, when both the shroud side diffuser ring and the hub side diffuser ring are provided, the static pressure efficiency η is
It can be seen from the graph of FIG. 8 that the static pressure efficiency η improves over the entire flow rate count φ.

  FIG. 9 shows the maximum static pressure efficiency (%) (bar graph I) of the centrifugal fan 23 of the present embodiment and the maximum static pressure efficiency (%) of a centrifugal fan having two-dimensional blades as a comparative example of the present invention. (Bar graph II). Note that the two-dimensional blade here refers to a blade having a uniform cross section perpendicular to the axial direction as it is displaced along the axial direction of the rotation axis of the centrifugal fan (for example, shown in FIGS. 13 to 14). Refers to the blade 121).

  As described above, the centrifugal fan 23 of the present embodiment includes the three-dimensional blades 21 (so-called three-dimensional blades) and a pair of diffuser rings 26 and 27. In the three-dimensional blade 21, the connection end 21c on the shroud 19 side has a curved portion 21d (see FIGS. 4 to 5). Moreover, the hub-side end 21e (see FIG. 6) of the rear edge 21b of the blade 21 is located on the front side in the rotational direction B of the centrifugal fan 23 relative to the shroud-side end 21f of the rear edge 21b.

  As can be seen from the bar graph II in FIG. 9, the maximum static pressure efficiency (bar graph II) in the case where the diffuser ring is provided on both the shroud side and the hub side in the centrifugal fan having the two-dimensional blade which is a comparative example of the present invention. B1) is improved by 1.9% compared with the maximum static pressure efficiency (see b2 of the bar graph II) when the diffuser ring is not provided.

  On the other hand, as shown by the bar graph I in FIG. 9, in the centrifugal fan 23 having the three-dimensional blades 21 as in the present embodiment, the diffuser rings 26 and 27 are provided on both the shroud side and the hub side. The maximum static pressure efficiency (see a1 in the bar graph I) is improved by 3.3% compared to the maximum static pressure efficiency (see a2 in the bar graph I) when the diffuser rings 26 and 27 are not provided. .

  From the above results, in the centrifugal fan, the configuration in which the three-dimensional blade 21 and the diffuser rings 26 and 27 are combined as in this embodiment is more than the configuration in which the two-dimensional blade and the diffuser ring are combined as in the comparative example. It is understood that the effect of improving the maximum static pressure efficiency (%) by providing the diffuser ring is great.

  Such a difference in effect is apparent when the wind speed distributions of the airflows blown from the centrifugal fans in the present embodiment and the comparative example are compared, as shown in FIGS. 10 (a) and 10 (b). Here, in FIGS. 10A and 10B, regions where the shadows near the outlets of the air outlets 28 and 128 are lighter indicate regions where the air velocity (wind velocity) is higher.

  FIG. 10A shows the wind speed distribution in the vicinity of the air outlet 28 of the centrifugal fan 23 having the above-described three-dimensional blade (see the blade 21 in FIGS. 4 to 6) and a pair of diffuser rings 26 and 27 in the present embodiment. It is shown. FIG. 10B shows a wind speed distribution in the vicinity of the air outlet 128 of the centrifugal fan 123 having the two-dimensional blade 121 and the pair of diffuser rings 126 and 127 as a comparative example.

  In the wind speed distribution shown in FIG. 10B, the air flow blown out from the blowout port 128 of the centrifugal fan 123 of the comparative example is separated from the shroud 119 and flows biased from the shroud 119 side to the hub 115 side. The wind speed distribution is non-uniform compared to the wind speed distribution at the outlet 28 of the centrifugal fan 23 in the present embodiment shown in FIG. Therefore, the function of recovering the dynamic pressure which is the role of the diffuser rings 126 and 127 in the centrifugal fan 123 of the comparative example (the function of converting the dynamic pressure into the static pressure, that is, the function of converting the kinetic energy of the airflow into the pressure energy) Indicates that is not working well. Therefore, since the portion of the kinetic energy of the airflow that is not converted to pressure energy increases, the improvement of the static pressure efficiency of the centrifugal fan 123 is suppressed.

  On the other hand, in the wind speed distribution of the centrifugal fan 23 of the present embodiment shown in FIG. 10A, the airflow blown out from the outlet 28 by the three-dimensional blade 21 is not biased toward the hub 15 side. Since the airflow flowing in the vicinity of the diffuser ring 26 is also secured, the wind speed distribution at the outlet 28 is substantially uniform.

  Specifically, since the airflow flows on the shroud 19 side through the extended recess 29 (see FIGS. 4 to 5) formed by the curved portion 21 d of the blade 21, separation of the airflow from the shroud 19 is less likely to occur. Moreover, the hub-side end 21e of the trailing edge 21b of the blade 21 is located on the front side in the rotational direction B of the centrifugal fan 23 relative to the shroud-side end 21f of the trailing edge 21b, so that the arrow F1 in FIG. As described above, the air flow easily flows to the shroud 19 side by flowing along the inclined front surface 21 g (that is, the surface on the rotation direction B side) of the blade 21.

  Therefore, the wind speed distribution at the air outlet 28 is substantially uniform. That is, the airflow blown out from the outlet 28 flows not only in the vicinity of the diffuser ring 27 on the hub side 15 side but also in the vicinity of the diffuser ring 26 on the shroud 19 side. Therefore, since the wind speed distribution at the air outlet 28 is uniform, the dynamic pressure can be recovered satisfactorily, and the portion of the kinetic energy of the airflow that is not converted into pressure energy is reduced. Efficiency can be improved.

  9 to 10, the centrifugal fan 23 of the present embodiment has a three-dimensional blade 21 and a pair of diffuser rings 26 and 27, so that the two-dimensional It can be seen that the static pressure efficiency is improved compared to a conventional centrifugal fan having vanes and a pair of diffuser rings.

  Other configurations of the indoor unit 31 are the same as those of a conventional ceiling-embedded cassette indoor unit. Specifically, it is as follows.

  As shown in FIG. 1, the bell mouth 25 of the blower 51 is disposed opposite to the front side F in the axial direction A with respect to the shroud 19. The bell mouth 25 has a curved shape whose outer diameter decreases toward the back side R.

  Further, as shown in FIG. 1, the heat exchanger 43 has a flat shape with a small thickness. The heat exchanger 43 is disposed so as to surround the periphery of the centrifugal fan 23 while standing upward from a dish-shaped drain pan 45 extending along the lower end portion thereof. The heat exchanger 43 includes, for example, a large number of fins and a plurality of pipes penetrating the fins, and has a structure in which heat is exchanged between the refrigerant passing through the pipes and the air around the fins. The drain pan 45 stores water droplets generated in the heat exchanger 43. The stored water is discharged through a drainage path (not shown). The air filter 41 has a size that covers the inlet of the bell mouth 25, and is provided along the suction grill 39 between the bell mouth 25 and the suction grill 39. The air filter 41 captures dust contained in the air sucked into the housing 33 from the suction grill 39.

  In the indoor unit 31 configured as described above, the centrifugal fan 23 of the blower 51 is rotated by driving the fan motor 11, so that the air flow F <b> 0 shown in FIG. 1 can be generated inside the indoor unit 31. It is. That is, the indoor air sucked from the suction grill 39 passes through the inside of the bell mouth 25 of the blower 51 toward the centrifugal fan 23. The air that has reached the centrifugal fan 23 is blown out to the outside in the radial direction of the centrifugal fan 23, and is cooled or heated by exchanging heat with the refrigerant when passing through the heat exchanger 43 disposed outside the centrifugal fan 23. . Thereafter, the heat-exchanged air is supplied into the room through the air outlet 37.

  While the indoor unit 31 is operating as described above, as shown in FIGS. 4 to 5, at the portion where the blade 21 and the shroud 19 are connected inside the rotating centrifugal fan 23, the connection end 21 c of the blade 21. The airflow F0 can smoothly flow through the extended recess 29 formed on the side 21c1 that contacts the airflow when moving in the rotation direction B, and the area where the airflow F0 is likely to be disturbed is reduced at the portion where the blade 21 and the shroud 19 are connected. It becomes possible to make it. Thereby, on the shroud 19 side, it is possible to suppress a decrease in the flow velocity of the airflow due to the turbulence of the airflow, and to prevent a separation area where the airflow is separated from the inner surface of the shroud 19, thereby improving the diffuser effect. To do.

(Feature)
(1)
In the indoor unit 31 of the present embodiment, in the configuration including the blower 51 including the centrifugal fan 23 having a diffuser ring, the blades 21 project inward in the shroud 19 as shown in FIGS. The connecting end 21c connected to the curved fan 21 has a curved portion 21d that is curved so as to incline toward the side 21c1 on which the airflow hits when the centrifugal fan 23 moves in the rotation direction B. For this reason, the portion where the shroud 19 and the blade 21 are connected at an acute angle is eliminated. As a result, the air flow F0 can flow smoothly at the portion where the blade 21 and the shroud 19 are connected (particularly, the expansion recess 29 formed on the side 21c1 that contacts the air flow when the connection end 21c moves in the rotation direction B). Thus, it is possible to reduce a region where the air flow F0 is easily disturbed in that portion. Thereby, on the shroud 19 side, it is possible to suppress a decrease in the flow velocity of the airflow F0 due to the turbulence of the airflow F0 and to prevent a separation area where the airflow F0 peels from the inner surface of the shroud 19. As a result, the diffuser effect for converting the kinetic energy of the airflow F0 in the shroud side diffuser ring 26 and the hub side diffuser ring 27 into pressure, particularly the diffuser effect in the shroud side diffuser ring 26 is improved.

(2)
Further, in the indoor unit 31 of the present embodiment, as shown in FIG. 6, at the trailing edge 21 b of the blade 21, the hub side end 21 e is positioned on the front side in the rotational direction B with respect to the shroud side end 21 f. Therefore, the inclination of the blades 21 with respect to the axial direction of the centrifugal fan 23 makes it easier for the airflow to flow toward the shroud 19 and further suppresses the separation of the airflow on the shroud 19 side. This also makes the air flow uniform in the axial direction A of the centrifugal fan 23, so that the diffuser effect that converts the kinetic energy of the air flow in the hub 15 side and the shroud side diffuser ring 26 into pressure, particularly the diffuser in the shroud side diffuser ring 26. The effect is improved.

(3)
In the indoor unit 31 of the present embodiment, as shown in FIG. 7, the outer diameter D2 of the hub side diffuser ring 27 and the outer diameter D3 of the shroud side diffuser ring 26 are respectively equal to the diameter D1 of the circumscribed circle of the plurality of blades 21. Since it is 1.1 times or more, the diffuser effect which converts the kinetic energy of the airflow in the hub 15 side and the shroud side diffuser ring 26 into pressure can be obtained with certainty.

(Modification)
(A)
In the above-described embodiment, the shroud side diffuser ring 26 and the hub side diffuser ring 27 are disposed so as to be inclined away from each other toward the respective distal ends, but the present invention is limited to this. is not. As a modification of the present invention, as shown in FIG. 11, the shroud side diffuser ring 26 has a portion bent in the axial direction A of the centrifugal fan 23 so as to be separated from the hub side diffuser ring 27, and the hub side diffuser ring 27 is The centrifugal fan 23 may extend in the radial direction R. In this configuration, the shroud side diffuser ring 26 is bent from the radially outer end of the shroud 19 in the axial direction A of the centrifugal fan 23 so as to be separated from the hub side diffuser ring 27, and the hub side diffuser ring 27 is bent by the radius of the centrifugal fan 23. It extends in the direction R. That is, since the shroud side diffuser ring 26 is shaped so as to expand in the axial direction A of the centrifugal fan 23, the airflow between the hub side diffuser ring 27 and the shroud side diffuser ring 26 can be more smoothly performed. is there. In addition, the hub-side diffuser ring 27 does not expand in the axial direction but extends in the radial direction, so that it is possible to configure the same plane as the inner portion of the hub 15 than the hub-side diffuser ring 27. It is possible to suppress an increase in cost. In addition, since the shroud 19 is conventionally curved, it is possible to suppress an increase in machining cost even if the shroud side diffuser ring 26 is shaped to expand in the axial direction A. Therefore, it is possible to suppress an increase in processing cost of the entire centrifugal fan 23.

  The flat plate-shaped hub 15 as described above is fixed to the rotating shaft 13 of the motor 11 by a boss 30 which is a separate component from the hub 15. The boss 30 may be fixed to the hub 15 or may not be fixed.

(B)
The shape of the shroud side diffuser ring 26 is not particularly limited in the present invention. For example, as another modification of the present embodiment, as shown in FIG. 12, the shroud side diffuser ring 26 is configured to further include a linearly extending portion 26a in addition to the bent portion 26b. Also good. Specifically, the shroud side diffuser ring 26 has a portion 26a extending linearly continuously from the edge of the shroud 19 and a portion 26b extending radially outward from the linearly extending portion 26a. May be.

  The linearly extending portion 26a is continuous with the radially outer edge of the shroud 19 and extends linearly in the radial direction. The arc-shaped portion 26b is continuous with the radially outer edge of the linearly-extending portion 26a, and is bent in an arc shape in a direction away from the hub-side diffuser ring 27 in the radial direction.

  In the modification shown in FIG. 12, since the shroud side diffuser ring 26 has a portion 26 a that extends linearly, the air flow F <b> 0 that flows along the inner wall of the shroud 19 reaches the shroud side diffuser ring 26. It is possible to smoothly flow along the linearly extending portion 26a. Therefore, it is possible to suppress the separation of the airflow F0 in the shroud side diffuser ring 26. In addition, since the shroud 19 and the shroud side diffuser ring 26 are smoothly continuous by the linearly extending portion 26a, the shroud 19 and the shroud side diffuser ring 26 are easily resin-molded.

  Although the shroud side diffuser ring 26 shown in FIG. 12 has a portion 26b extending in an arc shape, the present invention is not limited to this. The shroud side diffuser ring 26 may have a portion that is linearly bent in a direction away from the hub side diffuser ring 27 in the radial direction instead of the arc-shaped portion 26b.

  In addition, the shroud side diffuser ring 26 may be configured by only a portion 26a extending linearly or only a portion 26b bent in an arc shape.

(C)
In the above embodiment, the connecting end 21c of the blade 21 is orthogonal to the tangent C of the inner surface of the portion 19b projecting inward of the shroud 19, but the present invention is not limited to this. In the present invention, the connection end portion 21c is at an angle that does not lead to an acute angle with the portion 19b projecting inwardly of the shroud 19, for example, at an angle of 90 degrees or more with respect to the tangent C of the inner surface of the portion 19b. You may arrange as follows.

15 Hub 19 Shroud 19b Inwardly projecting portion 21 Blade 21b Rear edge 21c Connection end portion 21d Curved portion 21e Hub side end portion 21f Shroud side end portion 23 Centrifugal fan 26 Shroud side diffuser ring 27 Hub side diffuser ring 31 Indoor unit 51 Blower

Claims (5)

A hub (15);
A plurality of blades (21) arranged side by side in the circumferential direction of the hub (15);
A shroud (19) disposed on the opposite side of the hub (15) with respect to the blade (21),
The blade (21) has a side (21c1) on which the airflow hits when the connecting end (21c) connected to the inwardly projecting portion of the shroud (19) moves in the rotational direction of the centrifugal fan (23). ) Having a curved portion (21d) curved so as to incline toward the side,
The hub (15) has a hub side diffuser ring (27) protruding to the outer peripheral side of the blade (21),
The centrifugal fan (23), wherein the shroud (19) has a shroud side diffuser ring (26) protruding to the outer peripheral side of the blade (21). The hub side end portion (21e) at the rear edge (21b) of the blade (21) is positioned more forward in the rotational direction of the centrifugal fan (23) than the shroud side end portion (21f) of the rear edge (21b). doing,
The centrifugal fan (23) according to claim 1.   The outer diameter of the hub side diffuser ring (27) and the outer diameter of the shroud side diffuser ring (26) are each 1.1 times or more of the diameter of the circumscribed circle of the plurality of blades (21). Or the centrifugal fan (23) according to 2;   The said shroud side diffuser ring (26) has a part (26a) extended linearly to the radial direction of the said centrifugal fan (23) following the edge of the said shroud (19). The centrifugal fan (23) according to item.   The shroud side diffuser ring (26) has a portion bent in the axial direction of the centrifugal fan (23) so as to be separated from the hub side diffuser ring (27), and the hub side diffuser ring (27) is the centrifugal fan (27). The centrifugal fan (23) according to any one of claims 1 to 4, which extends in the radial direction of 23).