Impeller and outdoor unit

Abstract

To provide an impeller that can improve strength against stress that is generated with rotation.SOLUTION: An impeller includes: a hub 30; and a plurality of blades 50 provided in a side wall 32 of the hub 30. In a connection region between the hub 30 and each blade 50, on a fluid inflow side of the connection region, a ridge line P that connects a surface located on a front end side in a rotation direction of each blade 50 to an end surface of the hub 30 in axial cross-sectional view of the hub 30 smoothly continues.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an impeller and an axial flow fan. [Background technology]

[0002] Conventionally, there is known an impeller having a cylindrical hub and a number of blades provided on the outer peripheral surface of the hub. It is also known that this impeller is used in an axial flow fan or the like. In such an impeller, centrifugal force generated by rotation causes stress to concentrate around each connection area between the hub and the number of blades. For this reason, there is known an impeller having ribs formed around the connection area in order to increase the strength around the connection area while suppressing an increase in the weight of the impeller (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-108442 A [Patent Document 2] JP 2011-74817 A [Patent Document 3] JP 2001-115995 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the inventors analyzed the fracture strength of the impeller during rotation, and found that, in the periphery of each connection region between the hub and the blades, when there is a location where the inclination angle of the ridgeline of the surface located upstream in the fluid transport direction changes significantly in the axial cross section of the hub, stress is concentrated around that location. An object of the present invention is to provide an impeller that can improve the breaking strength against the stress generated during rotation. [Means for solving the problem]

[0005] The present invention relates to a rotor blade comprising a hub and a plurality of blades provided on an outer peripheral surface of the hub, a padded portion that rises toward the inflow side of air is provided across an inflow end face of the hub, a connection point between the hub and each of the blades, and a surface of a leading edge side of the blade near the connection point, a first rib that extends along the leading edge of each of the blades from the surface of the padded portion to a surface of the leading edge side of each of the blades, and a second rib that extends along the rotation direction of each of the blades is provided on the hub between the inflow end face and the padded portion, and the inflow end face and A surface of the second rib, a surface of the padding portion, and a surface of the first rib, The ridge line connecting the leading edge surface of the blade inclines toward the air inflow side from the inflow end face toward the leading edge surface of the blade, and a position on the ridge line where it bends toward the air inflow side relative to the inflow end face is defined as a first bend point, and a position on the ridge line where the leading edge surface of the blade bends toward the air inflow side relative to the ridge line is defined as a second bend point, and when a plurality of division points are provided which divide the area located between the first bend point and the second bend point into four equal parts, and virtual lines are provided which connect adjacent two of the first bend point, the second bend point, and the division points, the change in the inclination angle, which is the angle between adjacent virtual lines, is 20 degrees or less in all cases.

[0006] This suppresses the concentration of stress that occurs with rotation in the connection areas between the hub and each blade. Effect of the Invention

[0007] According to the present invention, it is possible to improve the strength against the stress generated by rotation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of an outdoor unit according to an embodiment of the present invention; [Diagram 2] Diagram showing the internal structure of the outdoor unit [Diagram 3] Perspective view of impeller [Figure 4] Plan view of the impeller from the air inlet side [Diagram 5] Plan view of the hub and the base of each blade [Figure 6] 6 is a cross-sectional perspective view taken along line VI-VI in FIG. [Figure 7] Cross-sectional view taken along line VI-VI in FIG. 3. [Figure 8] Perspective view of the hub from the air outlet side [Figure 9] Enlarged view of the ridgeline in Figure 7 [Figure 10] A diagram explaining the inclination angle between the inlet end surface bending point and the leading edge surface bending point. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The first invention is an impeller comprising a hub and a number of blades provided on the outer peripheral surface of the hub, and characterized in that a connection area between the hub and each blade, on the fluid inflow side of the connection area, in a cross-sectional view in the axial direction of the hub, is characterized by a ridge line connecting a surface located at the front end side of each blade in the rotational direction and the end face of the hub, which is smoothly continuous. This makes it possible to suppress concentration of stress generated as the impeller is rotated, at the connection areas between the hub and each blade, thereby improving the strength of the impeller.

[0010] The second invention is an impeller characterized in that on the fluid inflow side of the connection region, a padded portion is provided that rises from the surface located at the front end side of each blade in the rotational direction to the hub, and a first rib is provided on the surface of the padded portion and extends along the front end of each blade in the rotational direction, and a ridge line connects the surface located at the front end side of each blade in the rotational direction, the surface of the padded portion, the surface of the first rib, and the end face of the hub, and is smoothly continuous when viewed in cross section in the axial direction of the hub. With this, on the fluid inflow side of the connection area, the ridge connecting the surface located at the front end side in the rotational direction of each blade to the end face of the hub is smoothly continuous, thereby preventing the concentration of stress generated by the rotational driving of the impeller in the connection area between the hub and each blade.

[0011] A third invention is an impeller characterized in that the outer periphery of the first rib and the surface of the built-up portion are smoothly continuous. This prevents a large change in the inclination angle from occurring around the first rib, and suppresses stress concentration.

[0012] A fourth invention is an impeller characterized in that a plurality of first ribs are provided lined up in the rotation direction of each blade. This makes it possible to improve the breaking strength of the impeller against stress generated during rotation while suppressing an increase in the weight of the impeller. Also, the connection areas between the hub and each blade are not too thick compared to other parts of the impeller, which makes it possible to suppress molding defects during the manufacture of the impeller.

[0013] A fifth invention is an impeller characterized in that a second rib extending along the rotation direction of each blade is provided between the inlet end face of the hub and the padding portion. With this, the second rib smoothly connects the inflow side end face of the hub and the padding portion, thereby suppressing stress concentration at the connection point between the inflow side end face of the hub and the padding portion.

[0014] The sixth invention is an impeller characterized in that an engagement portion is provided on the fluid outflow side of the outer peripheral surface of the hub, with which the first rib engages with a built-up portion of the other impeller when the other impeller is stacked on top of the other impeller. According to this, by engaging the first rib and the padding portion of another impeller with the engagement portion, multiple impellers can be stacked stably, making it easier to produce and store the impellers.

[0015] A seventh invention is an impeller characterized in that, on the side of the end face of the hub, the ridge line extends in a straight line toward the front end side in the rotation direction of each blade and bends at a first bend point, and on the side of the surface located at the front end side in the rotation direction of each blade, the ridge line extends in a straight line toward the end face side of the hub and bends at a second bend point, and between the first bend point and the second bend point, the change in the inclination angle is 5 degrees or less when viewed in a cross section in the axial direction of the hub. This prevents a large change in the inclination angle of the ridge line connecting the surface located at the front end side of the rotation direction of each blade and the end face of the hub, thereby preventing the concentration of stress generated by the rotational drive of the impeller in the connection area between the hub and each blade.

[0016] An eighth aspect of the present invention is an impeller, wherein the ridge lines, when viewed in a cross section in the axial direction of the hub, have an inclination angle that changes by 20 degrees or less at any point. This prevents large changes in the inclination angle of the ridge line of the connection area located on the inflow side of the fluid, and allows the ridge line connecting the surface located on the front end side of the rotational direction of each blade in the connection area to the end face of the hub to be smoothly continuous.

[0017] A ninth aspect of the present invention is an axial flow fan comprising the impeller according to any one of the first to sixth aspects of the present invention. This makes it possible to obtain an axial flow fan having an impeller with improved fracture strength against stresses generated during rotation.

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an outdoor unit 1 of an air conditioner according to an embodiment of the present invention, and FIG. The outdoor unit 1 is used in the refrigeration cycle of an air conditioner, and as shown in Fig. 1, the outdoor unit 1 is equipped with a housing 2, and a front panel 2A arranged on the front side of the housing 2 is provided with a circular air outlet 4. This air outlet 4 is an opening that communicates between the inside and outside of the housing 2, and although it is omitted in Fig. 1, the front side of the air outlet 4 is covered by a grill 6 as shown in Fig. 2.

[0019] As shown in FIG. 2, the interior of the outdoor unit 1 is divided by a partition plate 8 into an air blower chamber 10 and a machine chamber 12. An axial fan 20, a mounting base 22, a heat exchanger (not shown), and the like are arranged in the blowing chamber 10. The blowing chamber 10 is also in communication with the above-mentioned air outlet 4, and an annular bellmouth 16 is provided on the periphery of the air outlet 4. The machine room 12 accommodates refrigeration cycle components such as a compressor 18 and refrigerant piping (not shown).

[0020] The axial fan 20 is equipped with a motor 24 and an impeller 26, and is a device that, when rotated, introduces air (fluid) from outside the housing 2 into the blower chamber 10, exchanges heat with a refrigerant flowing through a heat exchanger (not shown), and then releases the air again outside the outdoor unit 1. The motor 24 is a drive unit that rotates the impeller 26, and the motor 24 has a drive shaft 24A connected to the impeller 26. The impeller 26 is a rotating part that is rotated by the motor 24 to send out air in the axial flow direction.

[0021] The mounting base 22 is a support member that supports the motor 24 and the impeller 26, and includes a pair of posts 22A that extend upward from a bottom plate 2B that is disposed on the bottom surface of the housing 2. A mounting portion 22B is provided between the posts 22A, and the motor 24 is attached to the mounting portion 22B.

[0022] The bell mouth 16 has the function of guiding the air sent out by the impeller 26 to the outlet 4 to prevent leakage and increase the efficiency of the air blowing of the axial fan 20, and is connected to the surface of the front panel 2A that is located on the side of the air blowing chamber 10 so as to fit along the periphery of the outlet 4. The bellmouth 16 comprises an inlet section 16A with an enlarged diameter at the end located on the impeller 26 side, i.e., the air inlet side, an outlet section 16B with an enlarged diameter at the end located on the outlet 4 side, i.e., the air outlet side, and a cylindrical connecting section 16C connecting these. As shown in FIG. 3, a part of the impeller 26 on the air outlet side is located inside the bell mouth 16 in side view. The bell mouth 16 in this embodiment is made of metal and is formed by drawing.

[0023] Next, the configuration of the impeller 26 will be described. FIG. 3 is a perspective view of the impeller 26, and FIG. 4 is a plan view of the impeller 26 as viewed from the air inlet side. The impeller 26 of this embodiment is made of resin such as AS (acrylonitrile-styrene) material or PP (polypropylene) material, and is formed by integral resin molding using an injection molding die. As shown in FIG. 4, the impeller 26 includes a cylindrical hub 30 having a center of rotation, a side wall 32 that constitutes the outer circumferential surface of the hub 30, and a plurality of blades 50 that are integrally molded with the side wall 32. The impeller 26 is formed in a substantially circular shape in a plan view, and if the distance from the center of rotation to the outer edge 50B located at the outer end of each blade 50 is taken as radius r, the radius r is set to a dimension that optimizes the air volume of the axial flow fan 20 relative to the inner diameter dimension of the bellmouth 16. The radius of the impeller in this embodiment is 280 mm.

[0024] An inlet end face 34 located on the air inlet side of the hub 30 is closed by a plane perpendicular to the rotation axis, as shown in FIG. The outlet end 38, located on the air outlet side of the hub 30, is open, and inside the hub 30 is a boss 40 extending from the back surface of the inlet end face 34 to the outlet end 38, and a number of inner ribs 42 connecting the boss 40 and the side wall 32. A central hole 40A is provided in the center of the boss 40 along the direction of the rotation axis of the impeller 26. This central hole 40A penetrates from an end face 40B located on the outlet end 38 side of the boss 40 to the inlet end face 34. In this embodiment, the inner ribs 42 are formed at nine locations and reinforce the hub 30.

[0025] The impeller 26 of this embodiment is composed of three blades 50, and each blade 50 is attached to the hub 30 by connecting the base 50A located on the side wall 32 side to the side wall 32. The base 50A of each blade 50 is attached at an angle in the circumferential direction of the side wall 32 from the outlet end 38 to the inlet end face 34. In addition, the base 50A of each blade 50 is connected to the side wall 32 and the inlet end face 34 of the hub 30 at the end located forward in the rotation direction R of the impeller 26, and is connected to the side wall 32 at other points of the base 50A.

[0026] The outer edge 50B located at the outer end of each blade 50, like the base 50A, is formed in an inclined shape from the inlet side end face 34 of the hub 30 toward the outlet side end face 38 from the front side to the rear side in the rotational direction R of the impeller 26. If the end of each blade 50 located forward in the rotation direction R of the impeller 26 is referred to as a leading edge 50C (front end) and the end located rearward is referred to as a trailing edge 50D, the leading edge 50C extends forward in the rotation direction R toward the outer edge 50B of the impeller 26 and is inclined toward the air inflow side. Meanwhile, the trailing edge 50D extends forward in the rotation direction R toward the outer edge 50B of the impeller 26, but extends rearward in the rotation direction R near the rear end of the outer edge 50B.

[0027] Further, in the rotation direction R of the impeller 26, an outer edge rear end portion 52 located at the rear end of the outer edge 50B is provided with a notch portion 54 that is cut out in the radial direction of the impeller 26. Furthermore, in this embodiment, the thickness of each of the outer edge rear ends 52 of each of the blades 50 is formed to be thinner than the thickness of each of the blades 50 at other points.

[0028] Next, the connection structure between the base 50A of each blade 50 and the inlet end surface 34 of the hub 30 will be described. Fig. 5 is a plan view of the hub 30 and the base portion 50A of each blade 50, and Fig. 6 is a cross-sectional perspective view taken along line VI-VI in Fig. 5. Also, Fig. 7 is a cross-sectional view taken along line VI-VI in Fig. 5. As shown in Fig. 5, a padding portion 60 that bulges toward the air inflow side is provided at the connection portion (connection area) between each blade 50 and the inflow side end face 34 of the hub 30. In Fig. 5 and Fig. 6, the padding portion 60 is shaded for ease of explanation. In detail, each padding portion 60 is positioned on the forward side of the rotational direction R of the impeller 26, i.e., on the side of the leading edge 50C, and covers the entire portion of the base 50A of each blade 50 that is connected to the inlet side end face 34 of the hub 30. In addition, in the radial direction of the impeller 26, each padding portion 60 is provided from the inlet end face 34 of the hub 30 to the end portion of the base 50A of each blade 50 that is located on the leading edge 50C side, and to the leading edge side surface 50E of each blade 50 that is located in the vicinity of that end portion. Furthermore, a padding fillet 70 is provided at the connection between each padding surface 60A and each leading edge surface 50E. Each padding fillet 70 has a shape that rises gently toward the air inflow side, and each padding surface 60A and each leading edge surface 50E are smoothly connected by these padding fillets 70.

[0029] A plurality of first ribs 62 extending along the leading edge 50C are provided from the padding surface 60A of each of the padding portions 60 to the leading edge side surface 50E of each blade 50. In this embodiment, two first ribs 62 are provided, which are disposed adjacent to the leading edge 50C and aligned along the rotation direction R of the impeller 26. In the radial direction of the impeller 26, a pair of first ribs 62 provided on each padding surface 60A extends from the inlet end face 34 of the hub 30 to the leading edge surface 50E of the blade 50 in a plan view of the impeller 26. In addition, each first rib 62 is shaped not to block the flow path of the air sent out by the rotational drive of the impeller 26. Further, a rib fillet 72 is provided around each first rib 62. Each rib fillet 72 is formed around each first rib 62 so as to have an inclined shape that gently connects each first rib 62 and the padding portion surface 60A. This prevents stress from concentrating around the first rib 62 when the impeller 26 is driven to rotate, and increases the strength of the connection points between each blade 50 and the inlet end face 34 of the hub 30.

[0030] By providing these first ribs 62, the connection points between the base 50A of each blade 50 and the inlet end face 34 of the hub 30 are reinforced, thereby increasing the strength against stress generated as the impeller 26 is rotated. Furthermore, by providing a pair of first ribs 62 on each padding surface 60A, the increase in weight of the impeller 26 can be suppressed compared to the case where ribs are provided to cover the entire padding surface 60A. This makes it possible to suppress the power consumption of the outdoor unit 1 when the impeller 26 is driven to rotate. Furthermore, by providing a pair of first ribs 62 without covering the entire surface 60A of each padding portion, it is possible to prevent the connection portion between each blade 50 and the inlet end surface 34 of the hub 30 from being excessively thicker than other portions of the impeller 26. This makes it possible to prevent molding defects such as sink marks from occurring during the manufacture of the impeller 26. It is also possible to prevent variations in the amount of deformation of the impeller 26 caused by rotation and heat.

[0031] A second rib 64 extending along the rotation direction R of the impeller 26 is provided at the connection between the inlet end face 34 of the hub 30 and the padding surface 60A of the padding portion 60. In this embodiment, each second rib 64 is provided close to the first rib 62 arranged on the leading edge 50C side of the connection between the inflow side end face 34 of the hub 30 and the padding surface 60A of each padding portion 60. Each second rib 64 protrudes slightly toward the air inflow side, and the inflow side end face 34 of the hub 30 and the padding surface 60A of each padding portion 60 are smoothly connected by these second ribs 64. This makes it possible to suppress stress concentration between the inlet end face 34 of the hub 30 and the padding surface 60A of each padding portion 60 when the impeller 26 is driven to rotate.

[0032] 6 and 7, a ridgeline P connecting the leading edge surface 50E of each blade 50, each padding surface 60A, the surface of the first rib 62 arranged on the leading edge 50C side, and the inlet end face 34 of the hub 30 is smoothly continuous in a cross section in the axial direction of the hub 30. Specifically, when the inclination angle of each point of the ridgeline P is measured at a predetermined interval, the amount of change in the inclination angle is formed to be 0 degrees or more and 20 degrees or less at all points. In this embodiment, the amount of change in each inclination angle is formed to be 0 degrees or more and 5 degrees or less. Moreover, the ridge line P is inclined toward the air inflow side from the inflow end face 34 of the hub 30 toward the leading edge surface 50E of each blade 50.

[0033] Fig. 9 is a partial enlarged view of the ridge line P in Fig. 7, and Fig. 10 is a view for explaining the inclination angle between the inlet end face bending point A and the leading edge surface bending point B. For convenience of explanation, the positions of the padding portion 60, the first rib 62, and the second rib 64 are indicated by dashed lines in Fig. 9. Next, a method for quantitatively evaluating the gentleness of the ridgeline P will be described. 9(A), an extension line L10 of the ridge line P along the inlet end face 34 of the hub 30 extends in a substantially straight line toward the leading surface 50E, and the ridge line P is bent toward the air inlet side at an inlet end face bending point A (first bending point). Also, an extension line L11 of the leading surface 50E of each blade 50 extends in a substantially straight line toward the inlet end face 34 of the hub 30, and the ridge line P is bent toward the air inlet side at a leading surface bending point B (second bending point). That is, between the inflow side end surface bending point A and the leading edge side surface bending point B, the ridge line P is formed so as to be substantially convex towards the outflow side of the air in a cross section seen in the axial direction of the hub 30. At the ridge line P, the inlet end face 34 of the hub 30 extends in a substantially straight line towards the leading surface 50E, and the amount of change in the inclination angle is substantially 0 degree until the inlet end face bending point A. The leading surface 50E of each blade 50 extends in a substantially straight line towards the inlet end face 34 of the hub 30, and the amount of change in the inclination angle is substantially 0 degree until the leading surface bending point B.

[0034] Furthermore, between the inlet side end surface bending point A and the leading edge side surface bending point B, the ridgeline region L21 of the ridgeline P corresponds to the surface of the second rib 64, the ridgeline region L22 corresponds to the surface of the padding portion 60, and the ridgeline region L23 corresponds to the surface of the first rib 62. The inventors have found that in the conventional configuration, the extension lines L10 and L11 intersect at an acute angle at intersection point E, as shown by the dashed line, and a large acute inclination angle exists at intersection point E, so that stress is concentrated around this intersection point E.

[0035] As shown in Fig. 10, the ridgeline P is divided into four equal parts at a portion between the inflow end face bending point A and the leading surface bending point B by division points C1, C2, and C3 arranged at a predetermined interval. A virtual line connecting the inflow end face bending point A and the division point C1 is designated as L1, a virtual line connecting the division point C1 and the division point C2 is designated as L2, a virtual line connecting the division point C2 and the division point C3 is designated as L3, and a virtual line connecting the division point C3 and the leading surface bending point B is designated as L4. In this embodiment, the angle θ1 between the virtual line L1 and the virtual line L2 (referred to as the amount of change in the inclination angle), the angle θ2 between the virtual line L2 and the virtual line L3 (referred to as the amount of change in the inclination angle), and the angle θ3 between the virtual line L3 and the virtual line L4 (referred to as the amount of change in the inclination angle) are all 5 degrees or less.

[0036] This prevents the inclination angle of the ridge P connecting the leading edge surface 50E of each blade 50, each padding surface 60A, and the surface of the first rib 62 from changing significantly, thereby reducing stress concentration at the connection points between the hub 30 and each blade 50.

[0037] In the present embodiment, an example has been described in which a portion of the ridgeline P located between the inlet end face bending point A and the leading edge surface bending point B is divided into four equal parts by three division points C1, C2, and C3. However, this is not limited to this, and the division points may be disposed at any position and / or interval. Furthermore, the number of division points is not limited to three, and any number may be disposed. That is, at any location on the ridgeline P between the inlet end face bending point A and the leading edge surface bending point B, the amount of change in the inclination angle at any location is set to 5 degrees or less. In addition, in this embodiment, the change in the inclination angle of the ridge line P is between 0 degrees and 5 degrees, but the same effect can be obtained by measuring the inclination angle of each point of the ridge line P at a specified interval and finding that the change in the inclination angle is between 0 degrees and 20 degrees at every point.

[0038] Furthermore, in this embodiment, if the amount of change in multiple inclination angles on the ridgeline P is all 5 degrees or less, it is possible to suppress a large change in the inclination angle of the ridgeline P. However, this is not limited to the above, and if the difference in the amount of change in adjacent inclination angles on the ridgeline P is all 5 degrees or less, it is possible to suppress a large change in the inclination angle of the ridgeline P. In other words, the difference in the amount of change in adjacent inclination angles may be used as a method for quantitatively evaluating the gentleness of the ridgeline P. Specifically, if the difference between the angles θ1 and θ2 and the difference between the angles θ2 and θ3 in this embodiment are both 5 degrees or less, a large change in the inclination angle of the ridgeline P is suppressed. This makes the ridge line P gentle, and when the impeller 26 is driven to rotate, it is possible to suppress the concentration of stress between the inlet end face 34 of the hub 30 and the padding surface 60A of each padding portion 60. Even if the difference in the amount of change in the adjacent inclination angles is 10 degrees or less, the same effect can be obtained as when it is 5 degrees or less.

[0039] Next, the engagement portion 66 will be described. FIG. 8 is a perspective view of the hub 30 as viewed from the air outlet side. The side wall 32 is provided with three engagement portions 66 formed by cutting out the side wall 32 from the outlet end portion 38. These engagement portions 66 are provided at locations that overlap the locations where the padding portion 60 and the first rib 62 are provided, as viewed from the direction of the rotation axis of the impeller 26.

[0040] Each engagement portion 66 is formed with a padding engagement portion 66A and a rib engagement portion 66B, and each rib engagement portion 66B is formed by cutting out the side wall 32 deeper than each padding engagement portion 66A toward the inlet end face 34 of the hub 30. When the two impellers 26 are overlapped such that the outlet side of one impeller 26 contacts the inlet side of the other impeller 26, each padding portion 60 engages with the padding engagement portion 66A, and each pair of first ribs 62 engages with the rib engagement portion 66B. This allows a plurality of impellers 26 to be easily stacked even if the padding portion 60 and the first rib 62 are provided, and allows the impellers 26 to be stably stacked during production and storage.

[0041] The impeller 26 and the motor 24 are connected by inserting a drive shaft 24A of the motor 24 into a center hole 40A from the inlet end face 34 side of the impeller 26. When the motor 24 is driven, the impeller 26 is driven to rotate around the center hole 40A.

[0042] Next, the operation of this embodiment will be described. In the case of heating operation of the air conditioner, when the outdoor unit 1 starts operating, the compressor 18 is driven. The compressor 18 compresses the refrigerant sealed inside a refrigeration cycle composed of the compressor 18, an indoor heat exchanger (not shown), an expansion valve, a heat exchanger, and a refrigerant piping, and sends out the refrigerant through the refrigerant piping. After releasing heat in the indoor heat exchanger, the refrigerant flows through a pipe into an expansion valve, is decompressed by the expansion valve, and then flows further through a pipe into the heat exchanger. The outdoor unit 1 drives the compressor 18 and at the same time drives the motor 24 to rotate the impeller 26. The rotating impeller 26 sends air from the rear side of the outdoor unit 1 to the air outlet 4. The air being sent out passes through a heat exchanger, which promotes heat exchange between the refrigerant flowing through the heat exchanger and the air. The refrigerant that has exchanged heat with the air is condensed. The refrigerant then flows out of the heat exchanger, passes through a pipe, and flows into the compressor 18, where it is compressed again. On the other hand, the air that has exchanged heat with the refrigerant is discharged to the outside of the housing 2 from the air outlet 4 by the axial flow fan 20. By repeating this operation, the outdoor unit 1 absorbs heat from the outdoor air in the refrigeration cycle and releases it indoors. In addition, when the air conditioner is in cooling operation, the circulating direction of the refrigerant in the refrigeration cycle is opposite to that in heating operation.

[0043] Here, when the impeller 26 is driven to rotate, stress is generated at the connection points between each blade 50 and the inlet side end face 34 of the hub 30, more specifically, at the points located forward in the rotation direction R of the impeller 26 on the air inlet side of the connection points. Furthermore, when viewed in cross section in the axial direction of hub 30, if there is a location on the ridge line where the inclination angle changes significantly, stress generated by the rotational driving of impeller 26 will be concentrated at that location.

[0044] In this embodiment, by providing the padding portion 60 and the pair of first ribs 62 at the connection points between each blade 50 and the inlet end face 34 of the hub 30, the connection points can be reinforced. In addition, a ridge P connecting the leading edge surface 50E of each blade 50, the padding surface 60A, the surface of the first rib 62 arranged on the leading edge 50C side, and the inlet side end face 34 of the hub 30 is gently continuous. This makes it possible to suppress stress concentration at the connection points between each blade 50 and the inlet side end face 34 of the hub 30 when the impeller 26 is rotationally driven. This makes it possible to increase the strength of the impeller 26 against stresses generated by rotational driving.

[0045] Next, an experiment conducted by the inventors to analyze the strength of the impeller 26 of this embodiment will be described. In order to improve the strength of a conventional impeller, the inventors created multiple CAD (Computer-Aided Design) models with modified shapes and measured the strength of each model by static analysis. Specifically, the rotational breaking strength, i.e., strength, of each impeller model was determined as the rotational speed at which each impeller model would be broken when rotated. The unit was r / min. Adventure Cluster, a structural analysis software made by Allied Engineering Co., Ltd., was used for the static analysis.

[0046] First, the inventors analyzed the rotational fracture strength using a conventional impeller model. As a result, it was found that a large stress occurs at the air inflow side of the connection between each impeller blade and the hub, at a location located forward in the impeller rotation direction. Furthermore, the researchers discovered that if there is a point on the ridge line connecting each blade to the hub at the point where these stresses occur where the inclination angle changes significantly when viewed in cross section in the axial direction of the hub, stresses will be concentrated around that point. The rotational breaking strength of this conventional impeller was 2560 r / min.

[0047] Next, the inventors created several models in which the shape of the connection points between each impeller blade and the hub, which are located forward in the impeller rotation direction on the air inflow side, was deformed, and the rotational crushing strength was measured. As a result, the model with a padded portion and a pair of first ribs at that location showed the highest rotational breaking strength of 3185 r / min.

[0048] Furthermore, a mold was created using this model, an impeller was actually molded, and the rotational crushing strength was measured, resulting in a speed of 2960 r / min. In other words, the rotational crushing strength of this impeller model is about 15% higher than that of conventional impellers. In addition, the inclination angle of each point of the ridge line connecting the leading edge surface of each blade of this model, the surface of each padding portion, the surface of the first rib, and the inlet end face of the hub was measured at specified intervals, and the change in the inclination angle at every point was greater than 0 degrees and less than 20 degrees. From these results, the inventors discovered that the strength of the impeller 26 can be improved by forming the ridge line P continuously so that when the inclination angle of any point on the ridge line P is measured at a specified interval, the change in the inclination angle at any point is 20 degrees or less.

[0049] The above-described embodiment provides the following advantages. At the connection points between the hub 30 of the impeller 26 and each blade 50, a padding portion 60 is provided that rises from a leading edge surface 50E located on the leading edge 50C side of the impeller 26 to the inlet side end face 34 of the hub 30. A first rib 62 extending along the leading edge 50C of each blade 50 is provided on a padding portion surface 60A of each padding portion 60. A ridge P connecting the leading edge surface 50E and padding portion surface 60A of each blade 50, the surface of the first rib 62, and the inlet side end face 34 of the hub 30 is configured to be gently continuous in a cross section seen in the axial direction of the hub 30. This makes it possible to suppress the concentration of stress generated as the impeller 26 rotates at the connection points between the hub 30 and each of the blades 50, thereby increasing the strength of the impeller 26.

[0050] In this embodiment, a pair of first ribs 62 are arranged next to the leading edge 50C along the rotation direction R of each blade 50. This makes it possible to improve the strength of the impeller 26 against stress generated by the rotational driving of the impeller 26 while suppressing an increase in the weight of the impeller 26. Also, the connection points between the hub 30 and each blade 50 are not too thick compared to other points of the impeller 26, making it possible to suppress the occurrence of molding defects during the manufacture of the impeller 26.

[0051] In this embodiment, a rib fillet 72 is provided on the outer periphery of the first rib 62, and the first rib 62 and the build-up portion surface 60A are smoothly connected by this rib fillet 72. This prevents a large change in the inclination angle around the first rib 62, and suppresses stress concentration when the impeller 26 is driven to rotate.

[0052] Furthermore, in this embodiment, a second rib 64 extending along the rotation direction R of the impeller 26 is provided at the connection between the inlet end face 34 of the hub 30 and the padding surface 60A of each padding portion 60. This allows the inlet end face 34 of the hub 30 to be smoothly continuous with each padding surface 60A, making it possible to suppress stress concentration at the connection between the inlet end face 34 of the hub 30 and each padding surface 60A.

[0053] Furthermore, in this embodiment, the outflow end 38 of the side wall 32 of the hub 30 is provided with an engagement portion 66 that engages with the first rib 62 and the padding portion 60 of the other impeller 26 when the other impeller 26 is stacked. This allows multiple impellers 26 to be easily stacked even if the padding portions 60 and the first rib 62 are provided, and allows the impellers 26 to be stably stacked during production and storage.

[0054] In addition, in this embodiment, on the side of the inlet end face 34 of the hub 30, the ridge line P extends in a substantially straight line to the leading edge surface 50E of each blade 50 and bends at the inlet end face bending point A, and on the side of the leading edge surface 50E of each blade 50, it extends in a substantially straight line to the inlet end face 34 of the hub 30 and bends at the leading edge surface bending point B, and between the inlet end face bending point A and the leading edge surface bending point B, the change in the inclination angle of the ridge line P is 5 degrees or less when viewed in cross section in the axial direction of the hub 30. This makes it possible to suppress a large change in the inclination angle of the ridge P connecting the leading surface 50E of each blade 50 and the inlet end face 34 of the hub 30. Therefore, it is possible to suppress concentration of stress generated as the impeller 26 rotates in the connection area between the hub 30 and each blade 50.

[0055] Furthermore, in this embodiment, the ridgeline P is formed to be continuous so that when the inclination angle of any point on the ridgeline P is measured at a predetermined interval, the change in the inclination angle at any point is between 0 degrees and 20 degrees. This prevents the ridgeline P from changing significantly in inclination angle, and suppresses stress concentration at the connection points between the hub 30 and each blade 50.

[0056] The above-described embodiment is merely an example of one aspect of the present invention, and any modifications and applications are possible without departing from the spirit and scope of the present invention.

[0057] For example, the material of the impeller 26 in this embodiment is resin, but it is not limited to this and may be metal. Also, for example, the number of blades 50 in this embodiment is three, but is not limited to this, and may be two or four. In this embodiment, the outdoor unit 1 has the air outlet 4 opening on the front panel 2A, which is the side surface of the housing 2. However, the outdoor unit 1 may have an air outlet provided on the upper side. Also, the outdoor unit may have a plurality of impellers 26. [Explanation of symbols]

[0058] 1 Outdoor unit 2. Chassis 4 Air outlet 16 Bellmouth 16D inner surface 20 Axial Fan 22 Mounting stand 22A Post 24 Motor 24A Drive shaft 26 Impeller 30 Hub 32 Side wall (outer surface) 34 Inlet side end face 38 Outlet end 50 Feather 50A base 50B Outer edge 50C leading edge (front end) 50D trailing edge 50E Leading edge surface 60 Meat platter 60A Surface of the padding 62 First Rib 64 Second Rib 66 Engagement part 66A Filling part engagement part 66B Rib engagement part 70 Fillet of meat 72 Rib Fillet A Inflow side end face bending point (1st bending point) B Front edge side surface bending point (second bending point) C1, C2, C3 dividing points E Intersection L1, L2, L3, L4 virtual lines L10, L11 extension line L21, L22, L23 ridgeline area P ridgeline R Rotation direction θ1, θ2, θ3 angles (change in tilt angle)

Claims

1. A hub and a plurality of blades provided on an outer circumferential surface of the hub, a padding portion is provided on the inlet side of the hub, the connection portion between the hub and each of the blades, and the leading edge side surface of the blade in the vicinity of the connection portion; A first rib is provided from a surface of the padding portion to a surface of the leading edge side of each of the blades, the first rib extending along the leading edge of each of the blades, The hub is provided with a second rib extending along a rotation direction of each of the blades between the inlet end surface and the padding portion, a ridge line connecting the inflow side end surface, a surface of the second rib, a surface of the padding portion, a surface of the first rib, and a surface of a leading edge side of the blade is inclined toward the inflow side of the air from the inflow side end surface toward the surface of the leading edge side of the blade, At the ridge line, A position where the inlet end surface is bent toward the air inlet side is defined as a first bending point, a second bending point is a position where a surface of the leading edge side of the blade bends toward an air inflow side with respect to the ridge line; In the case where a plurality of division points that divide a portion located between the first bending point and the second bending point into four equal parts and virtual lines that connect adjacent two of the first bending point, the second bending point, and the division point are provided, The change in the inclination angle, which is the angle between adjacent virtual lines, is 20 degrees or less. An impeller characterized by:

2. The impeller according to claim 1 , An outdoor unit characterized by the above.

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