JP2012041878A - Outdoor unit for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fan unbalance as a propeller fan rotates even when the blade of a resin propeller fan provided in an outdoor unit for an air conditioner has been damaged by a foreign object flown in through a blowout duct.SOLUTION: An outdoor unit 201 for an air conditioner includes a resin propeller fan 101 having a plurality of blades 102, and configured to blow air upwardly. The blade 102 is provided with a stepped portion 108 that extends along a rear edge 106 having the upper end of the blade 102 as viewed from the direction perpendicular to the rotating axis of the propeller fan 101.

Description

  The present invention relates to an outdoor unit of an air conditioner, and more particularly to a resin propeller fan.

  In an outdoor unit of an air conditioner, even when a foreign object collides with a resin propeller fan during air conditioning operation and a blade is missing, the fan may continue to rotate without stopping operation if it is slightly damaged. If the fan is missing, the center of gravity of the fan deviates from the rotation axis, and balance cannot be achieved during rotation (hereinafter referred to as fan unbalance). Unit vibration increases when rotating in a fan unbalanced state. If air conditioning operation is continued without noticing this unit vibration, the force due to fan imbalance is applied to the motor and the parts that support the motor, the motor support and the chassis fixing part, etc. The part may be damaged and the motor may fall from the motor support.

  In particular, in an upper blow type outdoor unit in which the outlet is located at the upper part of the housing, when the motor falls, the fan fastened to the motor damages the heat exchanger, and in the worst case, the refrigerant is blown out. In general, the motor mounted on the top-blowing outdoor unit is large and heavy, and if the motor falls to the bottom of the housing, it may damage other refrigeration cycle components.

  In order to suppress fan imbalance, it is possible to prevent the fan from cracking. For example, in Patent Document 1, by forming a cover made of a synthetic resin having flexibility on the outer peripheral edge of the blade, even when a hard object hits the outer periphery of the blade during use, damage to the part is prevented. Techniques that can be performed are disclosed.

JP 2000-161295 A

  However, the resin generally has a property of becoming brittle while being hardened at a low temperature to increase rigidity. In addition, since the fan is rotating at high speed during operation, in the case of Patent Document 1, not only the cover but also the blade may be damaged due to the foreign object hitting, and the damaged part may be enlarged.

  An object of the present invention is to reduce fan unbalance during rotation even if a blade of a resin propeller fan is damaged.

  In order to achieve the above object, the present invention provides an outdoor unit of an air conditioner having a plurality of blades and having a resin propeller fan that blows air upward, perpendicular to the rotation axis of the propeller fan. The wing is provided with a step portion along the rear edge having the upper end of the wing as viewed from the direction of the wing.

  ADVANTAGE OF THE INVENTION According to this invention, even if the blade | wing of a resin propeller fan is damaged, the fan imbalance at the time of rotation can be reduced.

1 is a plan view of a suction surface side of a propeller fan according to a first embodiment of the present invention. AA sectional drawing of FIG. The front view of the outdoor unit of the air conditioner concerning this invention. The negative pressure surface side top view of the propeller fan concerning the 2nd Embodiment of this invention. BB sectional drawing of FIG. The figure which shows the case where the propeller fan concerning the 2nd Embodiment of this invention is damaged. The negative pressure surface side top view of the propeller fan concerning the 3rd Embodiment of this invention. The negative pressure surface side top view of the propeller fan concerning the 4th Embodiment of this invention. EE sectional drawing of FIG. The negative pressure surface side top view of the conventional propeller fan. FF sectional drawing of FIG. The suction surface side top view showing the range of the thin part of the propeller fan concerning this invention. Sectional drawing showing the relationship between the thin part and thick part of the propeller fan concerning this invention.

  1 is a plan view of the suction side of the propeller fan according to the first embodiment of the present invention, and FIG. 2 is a sectional view in the circumferential direction of the propeller fan according to the first embodiment of the present invention (AA in FIG. 1). FIG. 3 shows a front view of the outdoor unit of the air conditioner according to the present invention.

  As shown in FIG. 3, the outdoor unit 201 has a compressor 203, a heat exchanger 204, and the like arranged on the bottom plate 202, and is placed above the compressor 203 and the electrical component box 208 so as to be surrounded by the heat exchanger 204. Place. Further, the motor support 205, the motor 206, and the propeller fan 101 are disposed above the electrical component box 208, and the shroud 207 is disposed so as to surround the propeller fan 101. Air is sucked in from the lower part of the outdoor unit 201, heat is exchanged by the heat exchanger 204, and air is blown upward from the blow grill 209 through the propeller fan 101.

  Here, the configuration of the propeller fan 101 according to the first embodiment will be described.

  As shown in FIG. 1, the propeller fan 101 has a blade 102 fixed to a boss 109. Propeller fan 101 rotates in the direction of rotation 110, and the front edge of blade 102 in the rotation direction is referred to as front edge 105, and the rear edge is referred to as rear edge 106. The propeller fan 101 in this figure is a plan view seen from below the outdoor unit and shows the suction surface side. The same applies to the plan views of the propeller fan 101 thereafter.

  As shown in FIG. 2, the propeller fan 101 is configured so that the thickness on the rear edge 106 side is thinner than that on the front edge 105 side, and the step portion 108 is configured to provide a step difference in thickness at the boundary between the thick portion and the thin portion. Yes. The blade 102 constitutes a pressure surface 103, a suction surface thick portion 104 and a suction surface thin portion 107 which are suction surfaces.

  The difference from the conventional propeller fan is shown. FIG. 10 is a plan view of the suction side of a conventional propeller fan, and FIG. 11 is a circumferential sectional view (FF sectional view of FIG. 10) of the conventional propeller fan.

  As shown in FIG. 11, the conventional propeller fan 501 has a constant thickness from the front edge 105 to the rear edge 106, or the thickness gradually decreases from the front edge 105 side toward the rear edge 106 side. is doing. The thickness is not changed by providing a step.

  That is, the propeller fan 101 according to the first embodiment is characterized in that the thickness on the rear edge 106 side is made thinner than that on the front edge 105 side with an angular step. If there is no step portion 108 as in the prior art, there is no crack where stress concentrates, and if the foreign matter is large, the wing 109 may be broken in the vicinity of the joint between the boss 109 and the blade 102 and the entire blade may be broken. In an upper blow type outdoor unit in which the outlet is at the upper part of the housing, a fan and a motor for driving the fan are installed at the upper part of the outdoor unit. If the fan blades are greatly chipped, the motor rotation shaft will shake and lose balance, and the motor will fall. The motor mounted on the top blower type outdoor unit is large and heavy. If the motor falls to the bottom of the housing, it will damage other refrigeration cycle parts, or the fan fastened to the motor will damage the heat exchanger. In the worst case, it leads to a refrigerant jet.

  However, if configured as in the first embodiment, when a foreign object collides with the wing 102, stress concentrates on the stepped portion 108 along the trailing edge, and a thin portion (vacuum surface thin wall) with the stepped portion 108 as a boundary. Since the portion 107) is broken so as to separate, the damaged area can be reduced. The step portion 108 will be described in more detail with reference to FIG. 2, which refers to a contact portion between a line moving from the suction surface thick portion 104 to the suction surface thin portion 107 and the suction surface thin portion 107, where stress is concentrated. As a result, the suction surface thin portion 107 breaks. Thereby, the amount of fan imbalance can be reduced. As a result, it is possible to prevent the motor support 205 and the motor 206 from falling, and it is possible to prevent the equipment in the outdoor unit from being damaged.

  Foreign matter enters from the blowout grill 209 at the top of the outdoor unit. In addition to solids such as stones and dust, for example, when heating is performed during winter rain (especially drizzle), water droplets attached to the blowout grill freeze, and ice pillars that gradually grow downward can also become foreign objects. As shown in FIG. 3, the rear edge 106 of the blade 102 that is the upper end when viewed from the direction orthogonal to the rotation axis of the propeller fan 101 is closest to the blowout duct 209. Therefore, when the propeller fan 101 rotates at high speed during operation, foreign matter that has entered from the blowout duct 209 tends to collide with the trailing edge 106 that first appears as a portion of the blade 102 in the dropping direction. In particular, since the circled portion 111 in FIG. 3 is located above the rear edge 106, it is more likely to collide with a foreign object. This circled portion 111 corresponds to the position of the suction surface thin portion 107 and exists similarly for each blade. Since the speed of rotation of the propeller fan 101 is faster than the speed at which the foreign matter falls, the foreign matter cannot of course pass between the blades 102, and on the trailing edge 106 side before reaching the leading edge 105 side of the blade 102. collide. Therefore, the rear edge 106 side is cut off. As described above, when the foreign object collides, the fan unbalance amount can be reduced by actively dividing the trailing edge 106 side of the blade 102 into smaller pieces. As a result, the motor support 205 and the motor 206 can be prevented from being damaged and dropped.

  In the first embodiment shown in FIG. 2, the suction surface thin portion 107 is configured by reducing the thickness on the suction surface side, but the pressure surface is provided with a stepped portion on the pressure surface 103 side. Even if the thick portion and the pressure surface thin portion are configured and the trailing edge side is thin, it is sufficient if there is a stepped portion 108 where stress is concentrated. However, the fan performance is better when the wind flows smoothly, and the airflow changes (such as separation of the airflow) depending on the shape of the blade surface. The influence of the fan performance due to the airflow is greater on the pressure surface 103 than on the negative pressure surface. For this reason, when considering the fan performance, the stepped portion 108 is preferably provided on the suction surface. The same applies to the following embodiments.

  FIG. 4 is a plan view of the suction surface side of the propeller fan according to the second embodiment of the present invention, and FIG. 5 is a circumferential sectional view of the propeller fan according to the fourth embodiment of the present invention (BB in FIG. 4). Sectional view). FIG. 6 shows a diagram when the propeller fan according to the second embodiment of the present invention is broken.

As shown in FIG. 4, the propeller fan 101 is further provided with a suction surface rib 301 in the suction surface thin portion 107 of the first embodiment.
From FIG. 5, the circumferential cross-sectional shape of the wing 102 passing through the suction surface rib 301 has no thin portion on the rear edge side, and the thickness is constant or smoothly thin from the front edge 105 side to the rear edge 106 side. That is, it has a shape that does not provide a thick stepped portion. If the negative pressure surface rib 301 has the original thickness of the blade 102, the airflow is not greatly disturbed, so that the fan performance is unlikely to deteriorate.

  The negative pressure surface rib 301 is provided in an arc so as to follow a concentric circle centered on the rotation axis of the propeller fan 101. The suction surface rib 301 may be provided in a straight line instead of an arc. When viewed from the rotation axis of the propeller fan 101, it may be along the contour line of the blade 102. However, at the moment of collision, the wing 102 receives a force from the foreign material in a direction along the rotation direction. Therefore, if the suction surface rib 301 is provided in a direction along a concentric circle as shown in the figure, the suction surface rib 301 can be easily broken in a direction in which a force is applied, and the damaged area can be reduced.

  In FIG. 6, C part shows a damaged part when a foreign object collides between the suction surface ribs 301 on the trailing edge 106 side. The suction surface rib 301 increases the strength of the blade 102, and the boundary between the suction surface rib 301 and the suction surface thin portion 107 (step portion along the contour of the blade 102) plays the same role as the step portion 108. Since the stress concentrates on the blades 102, only the space between the suction surface ribs 301 of the blade 102 can be chipped. Part D shows a case where a foreign object collides with the suction surface rib 301. In this case, the suction surface rib 301 at the colliding portion is damaged and the area of the damage is larger than the portion C. However, since the suction surface ribs 301 on both sides restrict the spread of the damage portion, all the suction surface thin portions 107 are disposed. There is no lack. Therefore, since the damaged area can be further reduced as compared with the first embodiment, the fan unbalance amount can be further reduced. As a result, the motor support 205 and the motor 206 can be prevented from being damaged and dropped, and the equipment in the outdoor unit can be prevented from being damaged.

FIG. 7 shows a plan view of a propeller fan according to a third embodiment of the present invention.
As shown in FIG. 7, the propeller fan 101 is further provided with a trailing edge / blade tip rib 302 on the suction surface thin portion 107 of the second embodiment. By providing the trailing edge / blade tip rib 302, in addition to the effect of the above embodiment, when the propeller fan 101 is assembled to the housing during the manufacturing process, the trailing edge 106 or the thin portion of the blade tip is accidentally brought into contact with something. It has the effect of preventing chipping when letting it go. Note that the height of the trailing edge / wing tip rib 302 is preferably equal to or less than the suction surface rib 301 so as not to disturb the flow of wind along the blade surface.

  FIG. 8 is a plan view of a propeller fan according to the fourth embodiment of the present invention, and FIG. 9 is a circumferential sectional view of the propeller fan according to the fourth embodiment of the present invention (cross-sectional view taken along line EE in FIG. 8). Indicates.

  From FIG. 8, the propeller fan 101 is provided with a groove 401 substantially parallel to the contour line of the trailing edge 106, substantially parallel to the contour line of the diameter of the propeller fan 101, or concentrically.

  As shown in FIG. 9, a groove 401 is provided in a wing configured to have a constant thickness or smoothly thin from the leading edge 105 toward the trailing edge 106. With this configuration, when a foreign object collides with one section surrounded by the groove 401, only that section is missing, and when a foreign object collides with the groove 401, a section having the groove 401 on the side is present. Lack.

  Although the suction surface thin portion 107 is provided in the above embodiment, the suction surface thin portion 107 is not provided in the fourth embodiment. Instead, by providing the groove 401, the stress at the time of foreign object collision is concentrated in the groove 401, and the groove 401 is separated. The portion where the stress is concentrated is the deepest portion of the groove 401. That is, it is common that the step portion 108 and the groove 401 are the starting point of the crack, and the groove 401 is a thin-walled portion and becomes the step portion 108. That is, in the above-described embodiment, the state in which the suction surface thin portion 107 approaches 0 as much as possible can be said to be the groove 401 in the fourth embodiment. Here, the groove 401 along the contour line of the trailing edge 106 and the groove 401 along the rotation direction of the propeller fan 101 are illustrated. However, the shape is not limited to this shape, and the damaged portion is suppressed in the vicinity where the foreign object collides. Anything is acceptable.

  Even if comprised in this way, compared with the conventional propeller fan, a fan imbalance amount can be made small. As a result, the motor support 205 and the motor 206 can be prevented from being damaged and dropped, and the equipment in the outdoor unit can be prevented from being damaged.

  In the fourth embodiment shown in FIGS. 8 and 9, the groove 401 is provided on the suction surface, but the groove 401 may be provided on the pressure surface 103. However, considering the fan performance, it is preferable to provide the groove 401 on the negative pressure surface, as in the first embodiment.

FIG. 12 shows a plan view of the suction surface side showing the range of the thin portion of the propeller fan according to the present invention.
As shown in FIG. 12, in the plan view of the propeller fan 101 projected from the rotation axis direction, the blade tip length of the suction surface thin portion 107 is a, and the fan diameter position is the outermost diameter from the center of the boss 109. When the blade tip circumferential length (the outer peripheral length of one blade) is L1, the length is set to 0.08L1 ≦ a ≦ 0.1L1 from the trailing edge 106 of the propeller fan 101 to the blade tip.

Hereinafter, the grounds for defining the range of the thin portion of the propeller fan 101 will be described. As shown in FIG. 3, let us consider a case in which the distance from the blowing grill 209 to the trailing edge 106 of the blade 102 is 100 mm, and the ice frozen on the blowing grill 209 falls from the blowing grill 209. The time t until the ice reaches the trailing edge 106 after free-falling is the relation between the free-falling time and the displacement x = (1/2) gt ² (Equation 1)
(X: distance (m), g: gravitational acceleration (m / s ² ))
Therefore, t≈0.143 (s). Assume that immediately after the trailing edge 106 passes through the rotation, the ice has come to the height position of the trailing edge 106 (dropped 100 mm), and further dropped 30 mm therefrom. The time required to reach that point is approximately 0.163 seconds after the start of the fall from (Equation 1). That is, it takes 0.02 seconds to drop from a position of 100 mm to a position of 130 mm.

  On the other hand, consider the case where the wing 102 rotates 960 rpm. The wing 102 is thinner as the outer diameter, and is easily broken when hit by ice. Therefore, the moving speed (rotational speed) of the blade 102 at the fan diameter when the fan diameter that is the outermost diameter from the center of the boss 109 in the plan view is φ644 (0.644 m) is considered.

U = πDN (Equation 2)
(U: moving speed (m / s), D: fan diameter (m), N: rotational speed (s ^-1 ))
Therefore, U≈32.4 (m / s). The time required for the wing 102 to make a round is the outer peripheral length divided by (Equation 2), and is about 0.021 seconds when the number of the wings 102 is three. That is, 0.021 seconds after passing through a certain position, the blade rotates to a certain position. Further, the wing 102 is formed to be curved downward from the trailing edge 106 to the leading edge 105 in FIG. 3, and it takes 0.02 seconds to further fall from the trailing edge 106 by 30 mm. It is thought that it hits the part of the wing 102 which is 30 mm below the position. As the number of wings increases, the ice easily hits the wings 102.

  The length in the circumferential direction at the position where the ice collides is 30 mm below the trailing edge 106, and the suction surface thin portion 107 may be formed over the distance a from the trailing edge 106. Here, if θ1 = 6.65 ° and θ2 = 78 ° in FIG. 12, a = πD × (6.65 / 360) ≈0.0374 m, and L1 is calculated similarly to L1≈0.438 m. . When a is represented by L1, a≈0.08L1, so that a ≧ 0.08L1 is sufficient. However, even if the negative pressure surface thin portion 107 is too wide, the separation of the wind is likely to occur, the performance is deteriorated, and the strength is also lowered. Therefore, 0.08L1 ≦ a ≦ 0.1L1 is preferable.

  Also, assuming that the connecting portion between the blade 102 and the boss 109 is the inner periphery and the length between the inner periphery and the outer periphery is L2, from the blade tip of the propeller fan 101, the radial direction toward the rotation center is L2 / 3 or less. Of length. As propeller fan 101 moves inward in the radial direction of blade 102, the moving speed becomes slower than (Equation 2). If the moving speed becomes slower, the ice collision speed becomes slower. Since the impact force when ice collides is proportional to the square of the collision speed, the inner surface is less likely to be damaged, and the wing 102 on the boss 109 side does not have to be provided with the suction surface thin portion 107. The line on the boss 109 side of the negative pressure surface thin portion 107 is concentric with the fan diameter in the figure, but it does not necessarily have to be concentric. Further, the line on the front edge 105 side of the suction surface thin portion 107 is easy to design if it is an offset line equidistant from the rear edge 106, but is not necessarily limited to this shape. By setting the range shown in the shaded portion in FIG. 12, even if the suction surface thin portion 107 is provided, it is not necessary to deteriorate the fan performance.

FIG. 13 is a cross-sectional view showing the relationship between the thin portion and the thick portion of the propeller fan according to the present invention.
From FIG. 13, the relationship between the thickness t1 of the thin portion and the thickness t2 of the thick portion of the propeller fan 101 is t1 / t2 ≦ 1/2 before and after the stepped portion 108. When t2 is relatively thick, for example, 5 mm, the propeller fan 101 is hardly damaged by foreign matter. However, if it is too thick, the cooling time after molding of the resin becomes longer and the cost increases. Although breakage due to foreign matter must be taken into consideration, a thin blade 102 of about 1 mm ≦ t2 ≦ 3 mm is preferable in order to mold without increasing the cost.

  Propeller fan 101 is made of resin and is integrally formed by die cutting. Since there is a mold that pulls out directly above the vertical direction in FIG. 13, the line between the suction surface thick portion 104 and the suction surface thin portion 107 is a vertical line as shown in FIG. It must be tilted to the right as shown by the broken line. The configuration as shown by the broken line means that the step from the suction surface thick portion 104 to the suction surface thin portion 107 has a gentler slope. By tilting, the air can flow on the suction surface side, so that fan performance can be improved. Although the degree of inclination can be changed as appropriate, if the stepped portion 108 is angular so that the line constituting the suction surface thin portion 107 and the line constituting the inclined portion have an intersection in FIG. As a result, the suction surface thin portion 107 can be damaged from the step portion 108.

101 Propeller fan 102 Blade 103 Pressure surface 104 Negative pressure surface thick part 105 Front edge 106 Rear edge 107 Negative pressure surface thin part 108 Step part 109 Boss 110 Rotation direction 111 Round part 201 Outdoor unit 202 Bottom plate 203 Compressor 204 Heat exchanger 205 Motor support 206 Motor 207 Shroud (Bellmouth)
208 Electrical component box 209 Outlet grill 301 Negative pressure surface rib 302 Trailing edge / blade tip rib 401 Groove 501 Conventional propeller fan 502 Negative pressure surface

Claims (8)

In an outdoor unit of an air conditioner having a plurality of blades and having a resin propeller fan that blows air upwards,
An outdoor unit for an air conditioner, wherein the blade includes a step portion along a rear edge having an upper end of the blade as viewed from a direction orthogonal to a rotation axis of the propeller fan.   The outdoor unit for an air conditioner according to claim 1, further comprising a thin portion between the step portion along the rear edge and the rear edge.   The outdoor unit for an air conditioner according to claim 1 or 2, further comprising a step portion along the rear edge and the thin portion on the suction surface side of the propeller fan.   The outdoor unit for an air conditioner according to any one of claims 1 to 3, wherein the blade includes a step portion along a contour line of the blade as viewed from a rotation axis direction of the propeller fan.   The outdoor unit of an air conditioner according to claim 4, comprising a plurality of step portions along the contour line of the wing.   The outdoor unit for an air conditioner according to claim 5, comprising a plurality of step portions along the rear edge.   The propeller fan according to any one of claims 2 to 6, wherein the propeller fan is projected onto a plane from the direction of the rotation axis, the circumferential length at the outermost diameter of one blade is L1, and the length between the inner periphery and the outer periphery of the blade When the thickness is L2, the thin wall portion has a circumferential length a of 0.08L1 ≦ a ≦ 0.1L1 from the trailing edge to the outer periphery of the blade, and the diameter of the blade An outdoor unit for an air conditioner, wherein a length in a direction is L2 / 3 or less from an outer periphery of the blade.   8. The relationship between the thickness t1 of the stepped portion along the trailing edge and the thickness t2 of the blade not provided with the stepped portion along the trailing edge according to any one of claims 1 to 7, wherein t1 / t2 ≦ An air conditioner outdoor unit characterized in that it is halved.

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