JP6634704B2 - Cross flow fan and air conditioner using the same - Google Patents

Description

  The present invention relates to a cross flow fan and an air conditioner using the same, and particularly to a blade shape of the cross flow fan.

  The cross flow fan is used, for example, in an indoor unit 100 of a wall-mounted air conditioner as shown in Patent Document 1. In such an indoor unit 100, generally, as shown in FIG. 14, the heat exchanger 102 is arranged in a mountain shape so as to sandwich the upper part of the cross flow fan 101 from the front and rear when viewed in a cross section. The cross flow fan 101 is configured to draw in air whose temperature has been adjusted by the heat exchanger 102 from above and blow it out from below toward the blow grill 103 of the indoor unit 100. The cross flow fan 101 includes blades 104 having a general shape as shown in FIG. As shown in FIG. 15, the blade 104 has a shape that is curved in the rotation direction R toward the outside in the radial direction. The blade 104 has a maximum thickness 105 near the middle between the outer peripheral end portion 104a and the inner peripheral end portion 104b.

JP-A-2014-62465, FIGS. 1 and 3, paragraph 0026 JP-A-2001-193965, paragraph 0011 JP-A-2010-236540, FIG. JP-B-53-24643, FIG. 3

  By the way, in the blade row on the suction side of the cross flow fan 101 in the air conditioner (see the Y section in FIG. 14), a flow separation phenomenon occurs on the negative pressure surface 106 of the blade 104 as shown in FIG. I understood. FIG. 15 shows this state for one blade. As shown in this figure, peeling occurred on the negative pressure surface 106 of each blade 104 from a position 107 slightly near the inner periphery of the center of the chord. Further, it has been found that when such separation occurs, there is a problem that the pressure fluctuation on the blade surface increases and noise increases.

  In order to solve such a problem, as shown by a two-dot chain line in the rightmost blade 104 in FIG. 15, the direction of the inner peripheral side portion 104c of the blade 104 is directed in the direction opposite to the rotation direction R to reduce the separation region. Although a method is conceivable, it has been found that when each blade 104 is made in this manner, the work amount of the inner peripheral side tip portion 104b of the blade 104 decreases, and the pressure of the fan decreases.

  As the blades of the conventionally known cross flow fan, the following are known in addition to the general ones described above. Patent Literature 2 describes a blade in which the maximum thickness position of the blade is a position of 2 to 35% of the chord length from the inner periphery of the chord. Further, in Patent Document 3, notches are provided at predetermined intervals at the outer peripheral edge of the blade, and the blade thickness of this notch is made smaller than the blade thickness of the basic shape portion existing between the notches, It describes that a large number of dimples are formed on a negative pressure surface of a basic shape portion. Patent Literature 4 discloses a blade in which the position of the maximum thickness of the blade is a central portion of the chord and a concave groove is provided on a negative pressure surface at the central portion. However, it has also been found that any of these blades cannot provide a good effect on the noise problem.

  The present invention has been made in view of such circumstances, and uses a cross-flow fan that suppresses flow separation on a blade negative pressure surface located at a fan suction port to reduce noise. An object is to provide an air conditioner.

  A cross flow fan that solves this problem has an impeller in which a plurality of blades that are curved in the rotation direction are arranged in a circumferential direction, and the blades are arranged on a side opposite to a rotation direction of the impeller. A suction surface that is a convex curved surface that is convex in a direction opposite to the rotation direction; a pressure surface that is a concave curved surface that is arranged on the rotation direction side of the impeller and has a concave shape in the rotation direction; At the tip of each side, there are an outer tip and an inner tip formed by a curved surface connecting the negative pressure surface and the positive pressure surface, and the blade is provided with the outer tip and the inner tip. A line segment that is in contact with the rotation direction side of the circumferential tip is a chord line, and the distance between a straight line that is perpendicular to the chord line and that is in contact with the outer circumferential tip and the straight line that is in contact with the inner circumferential tip is When the chord length is set, the position of the maximum thickness is determined from the straight line on the inner peripheral side. An airfoil set to be 25 to 35% of the chord length measured in the chord line direction, and an axial direction of the impeller formed on the suction surface on the outer peripheral side of the maximum thickness. And an extending groove.

  According to such a configuration, the maximum thickness of the blade is located near the position where peeling is likely to start on the blade. For this reason, the vertical distance from the negative pressure surface of the blade to the air flow, that is, the separation area becomes small, so that the air flow easily flows along the negative pressure surface. In addition, by disturbing the air flow near the suction surface by the concave groove, the mixing of the air flow near the suction surface and the airflow that forms the main flow away from the suction surface can be promoted, thereby suppressing separation. As a result, noise can be reduced.

Further, it is preferable that the concave groove is arranged at a position of 45 to 65% of the chord length measured in the chord line direction from the straight line on the inner peripheral side.
When the concave groove is provided at this position, the effect of promoting the mixing of the air flow near the negative pressure surface and the main air flow at a position away from the negative pressure surface can be effectively exerted by the concave groove.

Further, it is more preferable that the concave groove is disposed at a position of 50 to 60% of the chord length measured in the chord line direction from the straight line on the inner peripheral side.
In addition, the blade has a notch having a notch cut in the air flow direction at predetermined intervals on an outer peripheral edge, and a basic shape of a blade formed between the notches is formed. And a plurality of dimples are preferably formed in the basic shape portion.

  According to such a configuration, since the cut portion is formed in the air flow direction, it is possible to suppress the flow of the air flowing into the blade from separating from the blade surface. Further, by forming dimples in the basic shape portion, the laminar flow on the negative pressure surface can be changed to turbulent flow, thereby suppressing the flow of air flowing into the blade from separating from the blade surface. it can. Therefore, the effect of further suppressing the peeling is exhibited, and the noise can be reduced.

An air conditioner according to the present invention uses the cross flow fan.
According to such a configuration, the noise of the cross flow fan used in the air conditioner is reduced, so that the noise of the air conditioner is also reduced.

  According to the above invention, a cross-flow fan and an air conditioner with reduced noise can be provided.

Sectional drawing of the indoor unit of the air conditioner which concerns on Embodiment 1 of this invention. FIG. 3 is a partial perspective view of a blade of a cross flow fan used in the air conditioner. FIG. The schematic diagram of the air flow in the cascade of the cross flow fan. The schematic diagram of the air flow in the cascade of the cross flow fan according to the comparative example 1 having no concave groove. The noise comparison diagram of Embodiment 1, Embodiment 2, and the comparative example 1. FIG. 9 is a partial perspective view of the blades of the cross flow fan according to the second embodiment of the present invention. FIG. The schematic diagram of the air flow in the cascade of the cross flow fan. FIG. 13 is a partial perspective view of the blades of the cross flow fan according to the third embodiment of the present invention. XI-XI sectional drawing in FIG. FIG. 9 is a noise comparison diagram of Embodiment 3 and Comparative Examples 2 and 3. The noise comparison diagram of the comparative example 2 and the comparative example 4. FIG. 2 is a cross-sectional view of a general wall-mounted air conditioner. Explanatory drawing of the blade negative pressure surface in the cross flow fan of the air conditioner.

  Hereinafter, a cross flow fan according to an embodiment of the present invention and a heat pump type wall-mounted air conditioner for cooling and heating using the same will be described. It should be noted that the present invention is not limited to the examples described below, but is indicated by the appended claims, and is intended to include all modifications within the scope and meaning equivalent to the appended claims. You.

(Embodiment 1)
FIG. 1 shows an indoor unit 1 of an air conditioner according to the present embodiment. The indoor unit 1 is installed on an indoor wall surface so that its longitudinal direction is horizontal, and has a cross-sectional structure shown in the drawing. In the following description, the left direction in FIG. 1 is referred to as the front, and the opposite direction is referred to as the rear. In addition, when indicating the left-right direction of the indoor unit 1, it refers to the direction when the rear is viewed from the front.

  As shown in FIG. 1, the indoor unit 1 includes a casing 2, a cross flow fan 3 housed in the casing 2, an indoor heat exchanger 4, a filter 5, a drain pan 6, and other internal devices.

  The casing 2 is formed to be long in the left-right direction, and is provided with a suction grille 7 that sucks indoor air on an upper surface side, and a blowout grill 8 that blows out temperature-controlled air in the indoor heat exchanger 4 below. ing. Although not shown, the outlet grill 8 is provided with horizontal blades and vertical blades for adjusting the direction of the blown air.

  The cross flow fan 3 is for circulating room air such that room air is drawn in from the suction grill 7 and blown out from the blowout grill 8. In the cross flow fan 3, the impeller 11 is arranged so that the axial direction is the left-right direction. The impeller 11 rotates in a direction indicated by an arrow R in the figure. The cross flow fan 3 has a front guider 12 and a rear guider 13 before and after the impeller 11. The cross flow fan 3 has a front guider 12 and a rear guider 13 so that a fan suction port 14 for sucking air from the front and above is formed, and a fan outlet 15 for blowing air downward is formed. The front guider 12 has an upper portion formed on a stabilizer 17 including a tongue portion 16 and a lower portion formed on a front wall portion 18 connected to the blowout grill 8. The rear guide 13 has an upper end formed on a tongue piece 19 extending above the impeller 11, a lower end connected to the blowout grill 8, and an intermediate portion 20 connecting the upper end and the lower end formed on a curved surface.

  The indoor heat exchanger 4 cools or heats the indoor air sucked from the suction grill 7 to adjust the temperature. The indoor heat exchanger 4 includes a front part and a rear part which form a mountain shape so as to sandwich the upper part of the cross flow fan 3 from front and rear. The front portion is formed in a shape in which a central height portion protrudes forward.

  The filter 5 removes dust in the room air sucked from the suction grill 7 and is disposed on the suction side of the indoor heat exchanger 4. The drain pan 6 receives and accumulates drain generated in the indoor heat exchanger 4 during the cooling operation, and is installed below the indoor heat exchanger 4.

Here, the blade 30 constituting the impeller 11 of the cross flow fan 3 according to the present embodiment will be described in detail.
As shown in FIG. 1, a plurality of blades 30 constituting the impeller 11 are arranged along a circumferential direction around a rotation axis 11 </ b> A of the impeller 11. The adjacent blades 30 are arranged at a predetermined interval. Each of the blades 30 is formed as a forward-facing blade that curves in the rotation direction R toward the outside in the radial direction.

  As shown in FIGS. 2 and 3, each blade 30 has a suction surface 31 and a pressure surface 32. The negative pressure surface 31 is a convex curved surface that is arranged on the side opposite to the rotation direction R of the impeller 11 and that is convex on the side opposite to the rotation direction R. The positive pressure surface 32 is a concave curved surface that is arranged on the side in the rotational direction R, that is, on the opposite side of the negative pressure surface 31 and that has a concave shape on the opposite side of the rotational direction R. Each blade 30 generates an airflow on the blade surface by the rotation of the impeller 11. Further, in each of the blades 30, a relatively small pressure distribution is generated on the negative pressure surface 31 and a relatively large pressure distribution is generated on the positive pressure surface 32 as the impeller 11 rotates.

  As shown in FIG. 3, each blade 30 has a distal end portion extending toward the outer peripheral side, and an outer peripheral end portion formed of a curved surface projecting radially outward and connecting the suction surface 31 and the pressure surface 32. 34. In addition, each blade 30 has an inner peripheral end portion 35 formed of a curved surface projecting radially inward and connecting the suction surface 31 and the pressure surface 32 at a distal end portion extending toward the inner peripheral side. .

  Here, the thickness (also referred to as blade thickness) of each blade 30 refers to the thickness between the suction surface 31 and the pressure surface 32, and is continuously between the outer peripheral end portion 34 and the inner peripheral end portion 35. Is changing. As shown in FIG. 3, in the blade 30, the chord line Lb refers to a line segment that is in contact with the outer circumferential end portion 34 and the inner circumferential end portion 35 in the rotation direction, and the chord length L1 is the blade length. It refers to the distance between a straight line Lg on the outer peripheral side that is perpendicular to the chord line Lb and contacts the outer peripheral end portion 34 and a straight line Ln on the inner peripheral side that contacts the inner peripheral end portion 35.

  Under such a definition, the basic shape of each blade 30 is such that the position of the maximum thickness Tm (that is, the position of the center Om of the maximum thickness Tm) is closer to the chord line Lb than the center of the chord length L1. Is also located on the inner peripheral side, and has a shape in which the thickness gradually decreases from the maximum thickness Tm toward the outer peripheral side distal end portion 34 and the inner peripheral side distal end portion 35. More specifically, when the distance from the straight line Ln on the inner peripheral side of the blade 30 to the position where the maximum thickness Tm is located is L2, the distance L2 is about 30% of the chord length L1. It is set to be.

  Further, as shown in FIGS. 2 and 3, each blade 30 has a groove extending in the axial direction of the rotation shaft 11 </ b> A (see FIG. 1) of the impeller 11 on the outer peripheral side of the position of the maximum thickness Tm on the suction surface 31. 36 are formed. The concave groove 36 is formed in a shallow arc-shaped concave surface. The position of the concave groove 36 is set such that when the distance from the straight line Ln on the inner peripheral side of the blade 30 to the center of the concave groove 36 is L3, the distance L3 is about 50% of the chord length L1. I have.

(Operation of Embodiment 1)
Next, an operation of the cross flow fan 3 according to the present embodiment configured as described above will be described.

  In the present embodiment, the position of the maximum thickness Tm of the blade 30 is located on the inner circumferential side from the center of the chord, specifically, about 30% of the chord length L1 from the straight line Ln on the inner circumferential side. Have been. Therefore, in the cross flow fan 3 according to the present embodiment, since the blade thickness of the blade 30 is increased where the air flow largely separates in the conventional one, the separation region in the air flow (that is, the blade 30 The distance from the negative pressure surface 31 to the air flow that separates) is reduced, and the separation of the air flow is suppressed.

  Further, in the cross flow fan 3 according to the present embodiment, the concave groove 36 parallel to the rotation axis 11A of the impeller 11 is formed on the outer peripheral side of the maximum thickness Tm on the negative pressure surface 31 of the blade 30. The concave groove 36 disturbs the flow near the suction surface 31 among the airflow flowing from the outer peripheral end portion 34 of the blade 30 to the suction surface 31. Thus, the mixing of the air flow near the suction surface 31 with the main flow of the air flow flowing away from the suction surface is promoted, and the separation of the air flow from the suction surface 31 is suppressed.

  As a result of such an operation, when the cross flow fan 3 is operated, the air flow in the cascade of the fan suction ports 14 of the cross flow fan 3 becomes as shown in FIG. That is, in the cross flow fan 3 according to the present embodiment, as shown by the solid arrows in the drawing, the separation phenomenon does not appear on the negative pressure surface 31 of the blade 30.

  On the other hand, it was found that the noise of the air conditioner according to Comparative Example 1 was larger than that of the air conditioner according to the present embodiment. Here, the air conditioner according to Comparative Example 1 is the cross flow fan 3 of the indoor unit 1 according to the present embodiment, in which the basic shape of the blade 30 is kept as it is and the concave groove 36 of the negative pressure surface 31 is eliminated. It is. Therefore, the blades of this cross flow fan are in the category described in Patent Document 2. In the following description of Comparative Example 1, the same components as those in Embodiment 1 will be described using the same reference numerals.

  FIG. 5 shows the air flow in the cascade of the fan suction ports 14 of the cross flow fan 3 used in the air conditioner according to Comparative Example 1. As shown in this figure, in the comparative example 1, since the separation suppressing action by the concave groove 36 is not obtained, the separation flow as indicated by a broken arrow toward the inner peripheral end portion 35 from a point past the maximum thickness Tm. S was seen.

(Effect of Embodiment 1)
Since the present embodiment is configured as described above, the following effects can be obtained.

(1) Since the separation phenomenon on the negative pressure surface 31 of the blade 30 of the cross flow fan 3 is suppressed, the noise of the cross flow fan 3 is reduced.
(2) In the indoor unit 1 of the air conditioner using such a cross flow fan 3, the noise of the cross flow fan 3 is reduced. Noise is also reduced.

  FIG. 6 specifically shows the effect of the air conditioner according to the present embodiment, and illustrates an air conditioner using the cross flow fan 3 according to the present embodiment and a cross filter according to Comparative Example 1. This is a comparison of the blowing sound with an air conditioner using a flow fan. As can be seen from this figure, the blowing sound of the air conditioner according to the present embodiment is indicated by a solid line, and has a noise of about 0.5 dBA lower than that of Comparative Example 1 indicated by a dashed line. .

  As described above, the position of the maximum thickness Tm of the blade 30 is preferably in the vicinity of a position where a separation flow is likely to occur. It has been found that it is preferable to set the distance L2 indicating the position of the maximum thickness Tm measured from the straight line Ln on the side in the direction of the chord line Lb to be 25% to 35% of the chord length L1.

  Although no specific data is shown in FIG. 6 for the conventional example shown in Patent Document 1, the noise was higher than that of the comparative example. FIG. 6 also shows the noise of the cross flow fan 3 according to the second embodiment described below, which will be described later.

(Embodiment 2)
Next, a second embodiment will be described with reference to FIGS. 7 to 9 and FIG. The second embodiment is different from the first embodiment in that the position of the concave groove 36 provided in the blade 30 of the cross flow fan 3 is changed. The other configuration is the same as that of the first embodiment. In this description, the same reference numerals are used for components common to the first embodiment, and the description thereof will be omitted or simplified.

  The blade 30 of the cross flow fan 3 according to the second embodiment has the same basic shape as the blade 30 according to the first embodiment, as shown in FIGS. The blade 30 according to the second embodiment sets the distance L3 to about 63 times the chord length L1 when the distance from the straight line Ln on the inner peripheral side in the direction of the chord line Lb to the center of the concave groove 36 is L3. %.

  The cross-flow fan 3 according to the second embodiment configured as described above performs substantially the same operation as the cross-flow fan 3 according to the first embodiment. However, since the position of the groove 36 is farther from the inner peripheral side, the distance between the position where the separation flow is likely to occur and the groove 36 is increased, whereby the effect of the groove 36 to suppress the separation flow is reduced. . For this reason, in the second embodiment, as shown in FIG. 9, the separation flow S is slightly generated near the inner peripheral end portion 35.

  The air conditioner using the crossflow fan 3 according to the second embodiment configured as described above has a blown sound shown by a broken line in FIG. As can be seen from this figure, the blowing noise of the air conditioner according to Embodiment 2 is larger than that of Embodiment 1, but smaller than that of Comparative Example 1.

  Further, the present inventors have repeatedly studied and found that the position of the concave groove 36 needs to be on the outer peripheral side of the position of the maximum thickness Tm, and from the straight line Ln on the inner peripheral side in the direction of the chord line Lb. It is preferable that the measured distance L3 to the center position of the concave groove 36 be set to 45% to 65% of the chord length L1. More preferably, the position of the concave groove 36 is such that the distance L3 is set to 50% to 60% of the chord length L1.

(Embodiment 3)
Next, a third embodiment will be described with reference to FIGS. The third embodiment is obtained by improving the outer peripheral edge of the blade 30 of the cross flow fan 3 in the second embodiment. In this description, the same reference numerals are used for components common to the first and second embodiments, and the description thereof will be omitted or simplified. Also, in Comparative Examples 2 to 4 described in connection with Embodiment 3, components common to Embodiment 1 will be described using the same reference numerals.

  As shown in FIGS. 10 and 11, blades 30 of cross flow fan 3 according to the third embodiment have notches 41 formed at regular intervals on the outer peripheral edge in blade 30 of the second embodiment. In addition, a plurality of dimples 43 are formed in the basic shape portion 42 formed between the cut portions 41. Therefore, the basic shape of the blade 30 according to the third embodiment is the same as that of the first and second embodiments, and the distance L2 indicating the position of the maximum thickness Tm is about 30% of the chord length L1. The position of the groove 36 in the blade 30 according to the third embodiment is the same as the position of the groove 36 in the blade 30 according to the second embodiment, and the distance L3 indicating the position of the groove 36 is a chord. It is about 63% of the length L1.

  The notch portion 41 has a notch portion 44 cut out in the air flow direction at predetermined and constant intervals at an outer peripheral edge portion, and the peripheral thickness of the notch portion 44 is made smaller than the thickness of the basic shape portion 42. And a cut groove 45 which is recessed as a slope between the periphery of the notch 44 and the negative pressure surface 31 of the basic shape portion 42. With such a configuration, the outer peripheral edge of the concave groove 36 that expands to the outer peripheral side is formed in a shape in which the cut portions 41 and the basic shape portions 42 are alternately repeated.

  The dimples 43 formed on the negative pressure surface 31 of one basic shape portion 42 formed between the cut portions 41 are shallow arc-shaped, and are three, two, three, and three rows from the outer peripheral side. Are arranged. Further, the three rows of dimples 43 are formed so as to become shallower from the row on the outer peripheral side to the row on the concave groove 36 side.

  Since the third embodiment is configured as described above, in addition to the function of the blade 30 in the second embodiment, the cut portion 41 and the dimple 43 suppress the separation of the airflow on the negative pressure surface 31. The effect is achieved.

  That is, according to the blade 30 according to the third embodiment configured as described above, since the plurality of cut portions 41 are formed at predetermined intervals in the outer peripheral edge portion, the air flowing into the blade 30 is formed. Easily flows into the cut portion 41, and the two-dimensionality of the air flow on the negative pressure surface 31 is broken. Further, the two-dimensionality of the airflow flowing into the blade 30 is further broken by the dimples 43, and the separation phenomenon of the airflow on the negative pressure surface 31 is further suppressed.

  According to the present embodiment, the blade 30 according to the second embodiment is added to the blade 30 according to the second embodiment by adding a cut-out portion 41 and a plurality of dimples 43 to suppress the separation of the air flow on the negative pressure surface 31. Experiments have shown that the blowing noise of the indoor unit using the cross flow fan 3 is reduced by about 0.6 dBA as compared with the case of the second embodiment.

  Further, in the third embodiment, the cross flow fans 3 according to the comparative examples 2 and 3 were produced, and these were assembled into the indoor unit 1 to confirm the effects of the present embodiment. FIG. 12 illustrates this.

  Here, in Comparative Example 2, the shape of the blade 30 in Embodiment 3 is changed. That is, the blade 30 according to Comparative Example 2 is different from the blade 30 according to Embodiment 3 in that the position of the maximum thickness Tm is changed to the center and the concave groove 36 is eliminated. In other words, Comparative Example 2 corresponds to the cross flow fan described in Patent Document 1 in which the above-described cut portion 41 and dimple 43 are provided at the outer edge of the blade 30. By comparing the comparative example 2 thus configured with the third embodiment, the position of the maximum thickness Tm of the blade 30 is set to be approximately the chord length L1 from the straight line Ln on the inner circumferential side as in the third embodiment. It is possible to understand the effect of setting the concave groove 36 on the outer peripheral side of the maximum thickness Tm of the blade 30 as well as 30%. FIG. 12 illustrates this, and the third embodiment has a difference as described above from the comparative example 2, and the blowing noise is reduced by about 1 dB compared to the comparative example 2 indicated by the broken line. Can be.

  In Comparative Example 3, the shape of the blade 30 in Embodiment 3 was changed as follows. That is, the blade 30 according to the comparative example 3 has no groove 36 compared to the blade 30 according to the third embodiment. In other words, Comparative Example 3 corresponds to a cross flow fan described in Patent Document 2 in which the above-described cut portions 41 and dimples 43 are provided at the outer peripheral edge of the blade 30. Comparing the comparative example 3 thus configured with the third embodiment, since the position of the maximum thickness Tm of the blade 30 is the same, the outer peripheral side of the maximum thickness Tm of the blade 30 as in the third embodiment The effect of locating the concave groove 36 in FIG. FIG. 12 illustrates this. In the third embodiment, the provision of the concave groove 36 lowers the transmission sound of about 0.5 dBA. Further, Comparative Example 3 is different from Comparative Example 2 in that the position of the maximum thickness Tm of the blade is formed not at the center but at a position closer to the inner peripheral side as in the third embodiment. Therefore, the effect of the position of the maximum thickness Tm can be known by comparing the comparative example 3 with the comparative example 2. According to FIG. 12, by changing the position of the maximum thickness Tm from the center position of the chord length L1 to the position of about 30% of the chord length L1 from the straight line Ln on the inner peripheral side in this way, 0.5 dBA blowing noise can be reduced.

  In addition, it was confirmed that the noise reduction effect could not be obtained by simply providing the concave groove 36 by making a cross flow fan having the blades of Comparative Example 4 and incorporating it in the indoor unit 1.

  That is, the blade 30 according to the comparative example 4 is different from the blade 30 of the comparative example 2 in that the concave groove 36 is provided at the same position as in the third embodiment. Therefore, the comparative example 4 is different from the third embodiment in that the position of the maximum thickness Tm is not at a position about 30% of the chord length L1 from the straight line Ln on the inner peripheral side, but at a substantially central portion of the chord length L1. It corresponds to the one that has been moved. The result of this comparison is shown in FIG. From a comparison between Comparative Example 4 and Comparative Example 2 in FIG. 13, in the blade 30 in which the position of the maximum thickness Tm is set at the center of the chord length L <b> 1, noise reduction can be achieved even if the concave groove 36 is provided near the outer periphery. It was found that not only the effect could not be obtained, but also that the blowing sound became slightly larger by about 0.5 dBA. From this, it was found that the correlation between the position of the maximum thickness Tm of the blade 30 and the concave groove 36 was important.

  Here, Table 1 is shown. Table 1 compares the differences in the characteristic configurations of the first to third embodiments and the comparative examples 1 to 4 in order to facilitate understanding of the first to third embodiments.

[Modification]
The description of each of the above embodiments is an example of a form that the crossflow fan 3 and the air conditioner according to the present invention can take, and is not intended to limit the form. The cross flow fan 3 and the air conditioner according to the present invention can take a form in which, for example, a modification of the above-described embodiment described below and at least two modifications that do not contradict each other are combined.

In each of the embodiments, the concave groove 36 has an arc-shaped cross section, but is not limited to this, and may have another cross section such as a triangle, a trapezoid, or the like.
The air conditioner according to each of the above embodiments is a heat pump type wall-mounted indoor unit for cooling and heating. For example, it may be a floor-standing type.

  In the third embodiment, the notch 41 provided on the outer peripheral edge of the blade 30 is formed by the notch 44 and the cut groove 45, but is simply formed at a predetermined interval on the outer peripheral edge. A triangular notch may be provided. Even when only such a notch is provided, the air flowing into the blade 30 can easily flow into the notch, thereby breaking the two-dimensionality of the air flow on the negative pressure surface 31 and suppressing the separation phenomenon of the air flow. it can.

In the third embodiment, the dimple 43 may be omitted.
In the third embodiment, the dimples 43 have different depths, but the dimples 43 in each row may have the same depth.

  -In Embodiment 1, the notch 41 and the dimple 43 similar to Embodiment 3 may be provided. Further, in the first embodiment, a notch or a dimple as in the modification according to the third embodiment may be provided.

Lb chord line Lg straight line Ln (outer circumference side) straight line L1 (inner circumference side) chord length Tm maximum thickness 3 cross flow fan 11 impeller 30 blade 31 suction surface 32 positive Compression surface 34 外 周 Outer end portion 35 内 Inner end portion 36 凹 Groove 41 切 Notch 42 基本 Basic shape 44 切 Notch 45 切 Cut

Claims (4)

A cross-flow fan (3) having an impeller (11) in which a plurality of blades (30) curved in a rotational direction are arranged in a circumferential direction,
The blade (30) is disposed on the side opposite to the rotation direction (R) of the impeller (11), and has a suction surface (31) that is a convex curved surface that is convex in the direction opposite to the rotation direction (R). And a positive pressure surface (32) which is arranged on the rotation direction (R) side of the impeller (11) and has a concave shape in the rotation direction (R), and a distal end portion on each of the outer peripheral side and the inner peripheral side. An outer peripheral end (34) and an inner peripheral end (35) formed by a curved surface connecting the negative pressure surface (31) and the positive pressure surface (32);
The blade (30) defines a line segment that is in contact with the rotation direction side of the outer peripheral end portion (34) and the inner peripheral end portion (35) as a chord line (Lb), and the chord line (Lb). ), And a distance between a straight line (Lg) contacting the outer peripheral end portion (34) and a straight line (Ln) contacting the inner peripheral end portion (35) is defined as a chord length (L1). The position of the maximum thickness (Tm) is set so as to be 25 to 35% of the chord length (L1) measured from the straight line (Ln) on the inner peripheral side in the direction of the chord line (Lb). and airfoil has the maximum thickness of the outer peripheral side of (Tm) formed in said suction surface (31), possess a groove (36) extending in the axial direction of the impeller (11),
The groove (36) is arranged at a position of 45 to 65% of the chord length (L1) when measured in the direction of the chord line (Lb) from the straight line (Ln) on the inner peripheral side. Flow fan. The said groove (36) is arrange | positioned at the position of 50-60% of the said chord length (L1) measured in the direction of the said chord line (Lb) from the said straight line (Ln) on the inner peripheral side. Item 7. The cross flow fan according to Item 1 . The blade (30) has a notch (41) having a notch (44) cut at predetermined intervals on an outer peripheral edge, and a blade formed between the notch (41). The cross flow according to claim 1 or 2 , further comprising a basic shape portion (42) having a basic shape of (30), wherein a plurality of dimples (43) are formed in the basic shape portion (42). fan. An air conditioner using the crossflow fan according to any one of claims 1 to 3 .