Cross flow fan and air conditioner

Abstract

To provide a cross flow fan capable of reducing noise.SOLUTION: A cross flow fan (101) comprises a plurality of impellers (30). The impeller has a plurality of blades (31) arrayed in a peripheral direction. Each blade has a negative pressure surface (31a), a pressure surface (31b) and an outer periphery-side tip part (31c). A pressure surface-side outer peripheral end (31e) periodically repeats a positional change in the peripheral direction and a positional change in a rotating direction along a rotation axis direction. A pressure surface-side outer peripheral end passes a peripheral recessed part position C hollowed in the peripheral direction and a peripheral projection position B projecting in the peripheral direction in changes in the peripheral direction. The pressure surface is periodically changed in curvature in accordance with the positions of the pressure surface-side outer peripheral end on an outer peripheral side with respect to the centers of the blades. The pressure surface-side outer peripheral end at the peripheral recessed part is located on the front side in rotating direction with respect to a circumscribed part (31f).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Relates to a cross-flow fan and an air conditioner.

Background Art

[0002] Conventionally, an indoor unit of an air conditioner (hereinafter referred to as an air-conditioning unit) that is installed on the side wall of a room instead of the ceiling, sucks air from the front or upper surface, and blows out the conditioned air from a blowout port at the lower part has been widely spread. For example, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 63-124899), inside the air-conditioning unit, a heat exchanger that conducts heat exchange between a refrigerant and air, and a cross-flow fan are accommodated.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In a cross-flow fan, there is a problem that the fluid blown out from the cross-flow fan collides with a solid wall such as a casing to generate noise.

Means for Solving the Problems

[0004] The cross-flow fan from the first perspective is cylindrical. The cross-flow fan includes a plurality of impellers. The impellers have a plurality of blades arranged in the circumferential direction. Each blade has a suction surface, a pressure surface, and an outer peripheral side tip. The suction surface is arranged on the side opposite to the rotation direction. The suction surface is a curved surface that bulges in the direction opposite to the rotation direction. The pressure surface is arranged on the rotation direction side. The pressure surface is a curved surface that depresses in the direction opposite to the rotation direction. The outer peripheral side tip connects the suction surface and the pressure surface. The pressure surface and the outer peripheral side tip are connected at the outer peripheral end on the pressure surface side. The suction surface and the outer peripheral side tip are connected at the circumscribed portion. The circumscribed portion is the portion where the outer peripheral side tip contacts the virtual circumscribed circle of the blade. The position of the outer peripheral end on the pressure surface side periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction. The position of the outer peripheral end on the pressure surface side passes through a circumferential concave portion position that depresses in the circumferential direction and a circumferential convex portion position that protrudes in the circumferential direction in the circumferential change. The curvature of the pressure surface periodically changes following the position of the outer peripheral end on the pressure surface side on the outer peripheral side with respect to the center of the blade. The position of the outer peripheral end on the pressure surface side in the circumferential concave portion is located on the front side in the rotation direction with respect to the circumscribed portion.

[0005] Here, since the position of the outer peripheral end on the pressure surface side periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction and passes through a circumferential concave portion position that depresses in the circumferential direction and a circumferential convex portion position that protrudes in the circumferential direction in the circumferential change, noise can be reduced.

[0006] The cross-flow fan from the second perspective is cylindrical. The cross-flow fan includes a plurality of impellers. Each impeller has a plurality of blades arranged in the circumferential direction. Each blade has a suction surface, a pressure surface, and an outer peripheral side tip. The suction surface is arranged on the side opposite to the rotation direction. The suction surface is a curved surface that bulges in the direction opposite to the rotation direction. The pressure surface is arranged on the rotation direction side. The pressure surface is a curved surface that depresses in the direction opposite to the rotation direction. The outer peripheral side tip connects the suction surface and the pressure surface. The pressure surface and the outer peripheral side tip are connected at the outer peripheral end on the pressure surface side. The suction surface and the outer peripheral side tip are connected at the circumscribed portion. The circumscribed portion is the portion where the outer peripheral side tip and the virtual circumscribed circle of the blade are in contact. The position of the outer peripheral side tip periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction. The position of the outer peripheral side tip passes through a circumferential concave portion position that depresses in the circumferential direction and a circumferential convex portion position that protrudes in the circumferential direction in the change in the circumferential direction. The curvatures of the pressure surface and the suction surface connected to the outer peripheral side tip periodically change following the outer peripheral side tip on the outer peripheral side with respect to the center of the blade. The position of the outer peripheral end on the pressure surface side in the circumferential concave portion is located on the front side in the rotation direction with respect to the circumscribed portion in the circumferential convex portion. The height of the unevenness in the circumferential direction on the pressure surface side is equal to the height of the unevenness in the circumferential direction on the suction surface side.

[0007] The cross-flow fan from the third perspective is cylindrical. The cross-flow fan includes a plurality of impellers. Each impeller has a plurality of blades arranged in the circumferential direction. Each blade has a suction surface, a pressure surface, and an outer peripheral side tip. The suction surface is arranged on the side opposite to the rotation direction. The suction surface is a curved surface that bulges in the direction opposite to the rotation direction. The pressure surface is arranged on the rotation direction side. The pressure surface is a curved surface that depresses in the direction opposite to the rotation direction. The outer peripheral side tip connects the suction surface and the pressure surface. The circumferential position of each blade cross-section in the rotation axis direction periodically repeats changes along the rotation axis direction without changing the mounting angle of the blade. In the view from the rotation axis direction, a convex portion cross-section that is a peak of the period and a concave portion cross-section that is a valley of the period partially overlap.

[0008] The cross-flow fan from the fourth perspective is any one of the cross-flow fans from the first to the third perspectives, and the blowing wind speed is uniform.

[0009] The cross-flow fan of the fifth aspect is any one of the cross-flow fans from the first aspect to the fourth aspect, and the period of change along the rotation axis direction is a waveform.

[0010] The cross-flow fan of the sixth aspect is any one of the cross-flow fans from the first aspect to the fifth aspect, and the blade has an inner peripheral side tip. The inner peripheral side tip connects the suction surface and the pressure surface on the inner peripheral side. The ratio H / L of the wave height H to the chord length L, which is the distance between the outer peripheral side tip and the inner peripheral side tip, is 0.041 or less.

[0011] The cross-flow fan of the seventh aspect is any one of the cross-flow fans from the first aspect to the sixth aspect, and the blade has an inner peripheral side tip. The inner peripheral side tip connects the suction surface and the pressure surface on the inner peripheral side. The ratio H / L of the wave height H to the chord length L, which is the distance between the outer peripheral side tip and the inner peripheral side tip, is 0.006 to 0.035.

[0012] The cross-flow fan of the eighth aspect is any one of the cross-flow fans from the first aspect to the seventh aspect, and the ratio P / H of the wave interval P to the wave height H is 0 to 39.

[0013] The cross-flow fan of the ninth aspect is any one of the cross-flow fans from the first aspect to the eighth aspect, and the ratio P / H of the wave interval P to the wave height H is 7 to 31.

[0014] The air conditioner of the tenth aspect includes any one of the cross-flow fans from the first aspect to the ninth aspect.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2A

Figure 2B

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Mode for Carrying Out the Invention

[0016] In the following description, the rotation axis O refers to the rotation axis of the impeller 30. The rotation axis direction refers to the direction in which the rotation axis O of the impeller 30 extends. The rotation direction refers to the direction in which the impeller 30 rotates. The circumferential direction is the circumferential direction of a circle centered on the rotation axis O. The radial direction is the radial direction of a circle centered on the rotation axis O. In addition, expressions indicating directions such as "up", "down", "front", etc. are used as appropriate, and these represent the respective directions in the state where the air conditioner unit 100 is installed and normally used. For example, the vertical direction is the vertical direction. In addition, expressions such as the same, uniform, parallel, etc. may be used, and these include not only the cases where they are completely the same, uniform, parallel, etc., but also the cases where they are substantially the same, uniform, parallel, etc.

[0017] <First Embodiment> (1) Overall Configuration As shown in FIG. 1, the air conditioner unit 100 is a wall-mounted indoor unit that is attached to an indoor wall surface. Further, the air conditioner unit 100 is connected to an air conditioner outdoor unit 91 disposed outdoors via a refrigerant pipe 93 to constitute an air conditioner 90. The air conditioner unit 100 performs indoor cooling operation and heating operation in response to an operation by a remote control or the like.

[0018] As shown in FIG. 2A, the air conditioner unit 100 includes a blower, a heat exchanger 20, and a filter 40.

[0019] (2) Blower The blower includes a cross-flow fan 101 including an impeller 30 and a casing 10.

[0020] (2-1) Cross-Flow Fan The cross-flow fan 101 is cylindrical. The cross-flow fan 101 includes a plurality of cylindrical impellers 30 that extend long in the horizontal direction and a motor that rotates the impeller 30.

[0021] As shown in FIG. 2B, the impeller 30 is formed by connecting a plurality of fan blocks 32. Although not particularly limited, the impeller 30 is configured, for example, by joining the fan block 32 and the end plate 33. The end plate 33 is disposed at one end of the impeller 30. The impeller 30 has a metal rotating shaft 34 on the rotation axis O. A boss portion (not shown) connected to a fan motor shaft (not shown) is provided at the center of the fan block 32 disposed at the other end of the impeller 30.

[0022] When the impeller 30 rotates, an air flow flowing from the heat exchanger 20 side to the blowout port 10b side is generated. When the impeller 30 rotates, air flows from the room through the filter 40 to the heat exchanger 20. The air that has passed through the heat exchanger 20 is blown into the room. The blowing wind speed is uniform.

[0023] Note that the rotation speed of the motor of the impeller 30 is changed by a control device (not shown). The control device built in the air conditioning unit 100 changes the rotation speed of the motor based on a user's operation input by a remote controller or the like.

[0024] In the impeller 30, a plurality of blades 31 are arranged in the circumferential direction.

[0025] As shown in FIGS. 3 to 7, each blade 31 has a negative pressure surface 31a, a pressure surface 31b, an outer peripheral side tip portion 31c, an inner peripheral side tip portion 31d, a pressure surface side outer peripheral end 31e, and an external connection portion 31f. In FIGS. 3 and 4, the outer shape of the blade 31 in solid lines indicates the outer shape of the blade 31 in the C cross section described later. The outer shape of the blade 31 in broken lines indicates a portion different from the outer shape of the blade 31 in the C cross section among the outer shapes of the blade 31 in the B cross section described later.

[0026] The negative pressure surface 31a is arranged on the side opposite to the rotation direction. The negative pressure surface 31a is a curved surface that bulges in the direction opposite to the rotation direction. The pressure surface 31b is arranged on the rotation direction side. The pressure surface 31b is a curved surface that depresses in the direction opposite to the rotation direction. The outer peripheral side tip 31c connects the negative pressure surface 31a and the pressure surface 31b on the outer peripheral side. The inner peripheral side tip 31d connects the negative pressure surface 31a and the pressure surface 31b on the inner peripheral side. The circumscribed portion 31f is the portion where the outer peripheral side tip 31c and the virtual circumscribed circle 30a of the blade 31 are in contact. The virtual circumscribed circle 30a is a virtual circle connecting the outer ends of a number of blades 31 (refer to the circle shown by the dotted line in Fig. 2).

[0027] The pressure surface 31b and the outer peripheral side tip 31c are connected at the outer peripheral end 31e on the pressure surface side. The negative pressure surface 31a and the outer peripheral side tip 31c are connected at the circumscribed portion 31f.

[0028] The position of the outer peripheral end 31e on the pressure surface side periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction. The period of the change along the rotation axis direction is in a waveform. The position of the outer peripheral end 31e on the pressure surface side passes through the circumferential concave portion position C that depresses in the circumferential direction and the circumferential convex portion position B that protrudes in the circumferential direction in the circumferential direction change. Hereinafter, the cross-section perpendicular to the rotation axis direction at the circumferential concave portion position C is referred to as the C cross-section, and the cross-section perpendicular to the rotation axis direction at the circumferential convex portion position B that protrudes in the circumferential direction is referred to as the B cross-section. The distance between adjacent C cross-sections and the distance between adjacent B cross-sections are equal. The outer peripheral end 31e on the pressure surface side in the C cross-section moves by a displacement angle θ in the circumferential direction with respect to the outer peripheral end 31e on the pressure surface side in the B cross-section.

[0029] The position of the outer peripheral end 31e on the pressure surface side does not change in the radial direction over the entire rotation axis direction. The distance from the rotation axis O to the outer peripheral end 31e on the pressure surface side in the C cross-section and the distance from the rotation axis O to the outer peripheral end 31e on the pressure surface side in the B cross-section are the same.

[0030] The curvature of the pressure surface 31b changes periodically following the position of the outer peripheral end 31e on the pressure surface side on the outer peripheral side with respect to the center of the blade 31. The center of the blade 31 is the position at 50% of the chord length L of the blade. The chord length L of the blade is the distance between the outer peripheral tip 31c and the inner peripheral tip 31d. Specifically, the chord length L is defined such that the line segment in contact with the rotation direction side of the outer peripheral tip 31c and the inner peripheral tip 31d is the chord line, and it is the distance between a straight line perpendicular to this chord line and in contact with the outer peripheral tip 31c and a straight line in contact with the inner peripheral tip 31d.

[0031] Specifically, the curvature of the pressure surface 31b changes periodically following the position of the outer peripheral end 31e on the pressure surface side from a position F1 which is a predetermined distance away from the center of the blade 31 towards the outer peripheral side. The distance from the rotation axis O to the position F1 is 90% or more of the radius of the impeller 30. The radius of the impeller 30 is the radius of the virtual circumscribed circle 30a connecting the outer ends of a large number of blades 31 when viewed in the rotation axis direction.

[0032] The curvature of the pressure surface 31b does not change over the entire length of the blade 31 in the rotation axis direction on the inner peripheral side with respect to the center of the blade 31.

[0033] The curvature of the suction surface 31a does not change over the entire length of the blade 31 in the rotation axis direction.

[0034] The position of the outer circumferential portion 31f on the suction surface 31a side does not change over the entire length of the blade 31 in the rotation axis direction. Therefore, the position of the outer circumferential portion 31f on the suction surface 31a side is the same in the C cross-section and the B cross-section. The position of the virtual circumscribed circle 30a is the same in the C cross-section and the B cross-section. However, the position of the pressure surface 31b of the outer circumferential portion 31f may move to the front side in the rotation direction in the B cross-section. Therefore, the area of contact between the outer circumferential portion 31f and the virtual circumscribed circle 30a may increase in the B cross-section.

[0035] The position of the outer peripheral end 31e on the pressure surface side in the C cross-section is located on the front side in the rotation direction with respect to the outer circumferential portion 31f.

[0036] The shape of the outer peripheral tip 31c changes periodically repeating the change in the rotation direction along the rotation axis direction.

[0037] The ratio H / L of the wave height H to the chord length L of the blade is 0.041 or less. The wave height H is defined as H = 2R × sin(θ / 2), where R is the radius (mm) of the impeller 30 and θ is the displacement angle (rad) of the outer peripheral end 31e on the pressure surface side at the C cross-section and the B cross-section. That is, the wave height H is the length of the chord of the displacement angle θ in the virtual circumscribed circle 30a. The chord length L of the blade is the distance (mm) between the outer peripheral tip 31c and the inner peripheral tip 31d. The ratio H / L of the wave height H to the chord length L of the blade is more preferably 0.006 to 0.035. The ratio H / L of the wave height H to the chord length L of the blade is even more preferably 0.008 to 0.033.

[0038] The ratio P / H of the wave interval P to the wave height H is 0 to 39. The wave interval P means the interval between adjacent B cross-sections and C cross-sections. The ratio P / H of the wave interval P to the wave height H is more preferably 7 to 31.

[0039] (2-2) Casing The casing 10 is an assembly of members that form the outer shell and frame of the air conditioning unit 100. The casing 10 supports and houses the filter 40, the heat exchanger 20, and the impeller 30.

[0040] An intake port 10a for taking in indoor air is formed in the upper part of the casing 10. An outlet port 10b for sending out the air-conditioned air into the room is formed in the lower part of the casing 10. The intake port 10a is located at a position higher than the rotation axis O which is the center of rotation of the impeller 30. More specifically, the intake port 10a is formed on the top surface (upper surface) of the casing 10 and sucks in indoor air from the space above the air conditioning unit 100. The outlet port 10b is located at a position lower than the rotation axis O. More specifically, the outlet port 10b is formed in the front side portion of the bottom surface of the casing 10 and blows out air in front of and below the air conditioning unit 100.

[0041] The casing 10 includes a front panel 15, a rear guide 18, and a stabilizer 17. The stabilizer 17 and the rear guide 18 form a scroll-shaped air outlet air flow path 10c through which air flowing from the impeller 30 to the air outlet 10b flows. The upper part of the rear guide 18 is located at a position higher than the rotation axis O. The front panel 15 is disposed on the front side of the filter 40. The stabilizer 17 is disposed on the front side of the rear guide 18. The stabilizer 17 has a tongue portion 71 and a support portion 73. The support portion 73 supports the tongue portion 71.

[0042] When the impeller 30 rotates, air flows from the room through the suction port 10a and the filter 40 to the heat exchanger 20. The air that has passed through the heat exchanger 20 flows into the outlet air flow path 10c and is blown out into the room from the air outlet 10b.

[0043] (3) Heat Exchanger and Filter The heat exchanger 20 is a fin-and-tube type heat exchanger having a "C" shape in a longitudinal sectional view. The shape of the heat exchanger 20 is not particularly limited. The heat exchanger 20 may be, for example, an inverted V shape. The heat exchanger 20 performs heat exchange between the air flowing from the suction port 10a side to the impeller 30 side and the refrigerant flowing through the tubes. The heat exchanger 20 is composed of a large number of aluminum heat transfer fins and a large number of tubes passing through a large number of holes formed in those heat transfer fins. The tubes, which are copper heat transfer tubes, have an outer diameter of 5 mm or 4 mm.

[0044] The upstream side of the air flow of the impeller 30 is covered by the filter 40. Specifically, the heat exchanger 20 located above and in front of the impeller 30 is covered by the filter 40. The filter 40 collects dust contained in the air flowing from the suction port 10a to the heat exchanger 20.

[0045] (4) Features (4-1) In the blade 31 of the cross-flow fan 101, the position of the outer peripheral end 31e on the pressure surface side periodically repeats changes in the circumferential direction and changes in the rotational direction along the rotation axis direction. The position of the outer peripheral end 31e on the pressure surface side passes through a circumferential concave position C that is recessed in the circumferential direction and a circumferential convex position B that protrudes in the circumferential direction in the circumferential change. The curvature of the pressure surface 31b periodically changes following the position of the outer peripheral end on the pressure surface side on the outer peripheral side with respect to the center of the blade. The position of the outer peripheral end 31e on the pressure surface side in the circumferential concave portion C is located on the front side in the rotational direction with respect to the circumferential connecting portion 31f.

[0046] Thereby, the airflow blown out from the cross-flow fan 101 can be diffused. Therefore, it is possible to suppress the organized and rapid growth of the turbulence in the wake of the blade. In addition, the size of the unevenness can be reduced, and it is possible to suppress the flow from gathering in the valley portion. Therefore, it is possible to reduce the density of the air volume in the mountain valley and reduce the turbulence of the wind. As a result, the noise can be reduced.

[0047] (4-2) In the cross-flow fan 101, the blown air velocity is uniform. Here, the turbulence of the wind can be reduced.

[0048] (4-3) The period of the change along the rotation axis direction is wavy. Therefore, the shape of the blade 31 changes smoothly. Thereby, it is possible to prevent the turbulence of the airflow due to sudden changes, so it is easy to reduce the noise.

[0049] (4-4) The ratio H / L of the wave height H to the chord length L of the blade is 0.041 or less. Here, the wave height H is small with respect to the chord length L of the blade. Therefore, the bias of the airflow can be suppressed. Thereby, the airflow can be diffused and the organized turbulence can be suppressed.

[0050] (4-5) The ratio H / L of the wave height H to the chord length L of the blade is 0.006 to 0.035. Here, the turbulence of the airflow can be further suppressed.

[0051] (4 - 6) The ratio P / H of the wave interval P to the wave height H is from 0 to 39. Therefore, the bias of the air current can be suppressed. Thereby, the air current can be diffused and the organized turbulence can be suppressed.

[0052] (4 - 7) The ratio P / H of the wave interval P to the wave height H is from 7 to 31. Here, the turbulence of the air current can be further suppressed.

[0053] (4 - 8) The air conditioner 90 includes the above cross - flow fan 101. Here, the noise can be reduced.

[0054] <Second Embodiment> The cross - flow fan 101 of this embodiment includes almost all of the configurations of the cross - flow fan 101 of the first embodiment. Hereinafter, the description will focus on the differences between the cross - flow fan 101 of this embodiment and the cross - flow fan 101 of the first embodiment.

[0055] As shown in FIGS. 8 to 12, the position of the pressure - side outer - peripheral end 31e periodically repeats changes in the circumferential direction and changes in the rotational direction along the rotation - axis direction. Therefore, the position of the pressure - side outer - peripheral end 31e changes in the C - cross - section and the B - cross - section. The pressure - side outer - peripheral end 31e in the C - cross - section moves by a displacement angle θ in the circumferential direction with respect to the pressure - side outer - peripheral end 31e in the B - cross - section.

[0056] The position of the pressure - side outer - peripheral end 31e does not change in the radial direction over the entire rotation - axis direction. Therefore, the distance from the rotation axis O to the pressure - side outer - peripheral end 31e in the C - cross - section is the same as the distance from the rotation axis O to the pressure - side outer - peripheral end 31e in the B - cross - section.

[0057] The position of the outer circumferential portion 31f changes along the rotation axis direction. Therefore, the position of the outer circumferential portion 31f changes in the C cross-section and the B cross-section. The outer circumferential portion 31f in the C cross-section moves by a displacement angle θ in the circumferential direction with respect to the outer circumferential portion 31f in the B cross-section. The position of the virtual circumscribed circle 30a moves by a displacement angle θ in the circumferential direction in the C cross-section and the B cross-section.

[0058] The position of the outer circumferential portion 31f does not change in the radial direction over the entire rotation axis direction. Therefore, the distance from the rotation axis O to the outer circumferential portion 31f in the C cross-section is the same as the distance from the rotation axis O to the outer circumferential portion 31f in the B cross-section.

[0059] The position of the outer peripheral side tip portion 31c periodically repeats changes in the circumferential direction and changes in the rotational direction along the rotation axis direction. The period of the change along the rotation axis direction is wavy. The position of the outer peripheral side tip portion 31c passes through the circumferential concave portion position C that is recessed in the circumferential direction and the circumferential convex portion position B that protrudes in the circumferential direction in the change in the circumferential direction. The outer peripheral side tip portion 31c in the C cross-section moves by a displacement angle θ in the circumferential direction with respect to the outer peripheral side tip portion 31c in the B cross-section.

[0060] The position of the outer peripheral side tip portion 31c does not change in the radial direction over the entire rotation axis direction.

[0061] The curvature of the pressure surface 31b changes periodically following the position of the outer peripheral side tip portion 31c on the outer peripheral side with respect to the center of the blade 31. Specifically, the curvature of the pressure surface 31b changes periodically following the position of the outer peripheral side tip portion 31c starting from a position F1 that is a predetermined distance away from the center of the blade 31 toward the outer peripheral side. The distance from the rotation axis O to the position F1 is 90% or more of the radius of the impeller 30.

[0062] The curvature of the pressure surface 31b does not change over the entire length in the rotation axis direction on the inner peripheral side with respect to the center of the blade 31.

[0063] The curvature of the negative pressure surface 31a changes periodically following the position of the outer peripheral side tip 31c on the outer peripheral side with respect to the center of the blade 31. Specifically, the curvature of the negative pressure surface 31a changes periodically following the position of the outer peripheral side tip 31c from a position F2 that is a predetermined distance away from the center of the blade 31 toward the outer peripheral side. The distance from the rotation axis O to the position F2 is 90% or more of the radius of the impeller 30.

[0064] The curvature of the negative pressure surface 31a does not change over the entire length in the rotation axis direction of the blade 31 on the inner peripheral side with respect to the center of the blade 31.

[0065] The position of the outer peripheral end 31e on the pressure surface side in the C cross-section is located on the front side in the rotation direction with respect to the circumscribed portion 31f in the B cross-section.

[0066] The height H2 of the unevenness in the circumferential direction on the pressure surface side is equal to the height H3 of the unevenness in the circumferential direction on the negative pressure surface side.

[0067] Here, the shapes of both surfaces of the blade 31 change. Therefore, as shown in FIG. 13, it is possible to eliminate the portion where the thickness of the outer peripheral side tip 31c increases. Thereby, it is possible to suppress the loss and noise generated by the collision between the airflow and the outer peripheral side tip 31c of the blade 31 when the airflow flows into the fan.

[0068] <Third Embodiment> The cross-flow fan 101 of the present embodiment includes almost all of the components included in the cross-flow fan 101 of the first embodiment. Hereinafter, the description will focus on the differences between the cross-flow fan 101 of the present embodiment and the cross-flow fan 101 of the first embodiment.

[0069] As shown in FIGS. 14 to 17, the circumferential positions of the respective blade cross-sections in the rotational axis direction periodically repeat and change along the rotational axis direction. At this time, the mounting angle θ2 of the blade 31 does not change over the entire rotational axis direction. The mounting angle θ2 of the blade 31 is the angle formed by the blade chord line and the virtual straight line extending from the outer peripheral end 31e on the pressure surface side to the rotational axis O in a cross-section perpendicular to the rotational axis direction. The blade chord line is a line segment that contacts the outer peripheral tip 31c and the inner peripheral tip 31d on the rotational direction side.

[0070] In the view in the rotational axis direction, the convex portion cross-section (B cross-section), which is the cross-section that forms the peak of the period, and the concave portion cross-section (C cross-section), which is the cross-section that forms the valley of the period, partially overlap. The cross-sectional shape of the blade 31 in the B cross-section is the same as the cross-sectional shape of the blade 31 in the C cross-section. The cross-section of the blade 31 in the B cross-section is displaced by an angular displacement θ in the circumferential direction with respect to the cross-section of the blade 31 in the C cross-section.

[0071] The position of the outer peripheral end 31e on the pressure surface side periodically repeats changes in the circumferential direction and changes in the rotational direction along the rotational axis direction. Therefore, the position of the outer peripheral end 31e on the pressure surface side changes between the C cross-section and the B cross-section. The outer peripheral end 31e on the pressure surface side in the C cross-section is displaced by an angular displacement θ in the circumferential direction with respect to the outer peripheral end 31e on the pressure surface side in the B cross-section.

[0072] The position of the outer peripheral end 31e on the pressure surface side does not change in the radial direction over the entire rotational axis direction. Therefore, the distance from the rotational axis O to the outer peripheral end 31e on the pressure surface side in the C cross-section is the same as the distance from the rotational axis O to the outer peripheral end 31e on the pressure surface side in the B cross-section.

[0073] The position of the circumscribing portion 31f changes along the rotational axis direction. Therefore, the position of the circumscribing portion 31f changes between the C cross-section and the B cross-section. The circumscribing portion 31f in the C cross-section is displaced by an angular displacement θ in the circumferential direction with respect to the circumscribing portion 31f in the B cross-section. The position of the virtual circumscribed circle 30a is displaced by an angular displacement θ in the circumferential direction between the C cross-section and the B cross-section.

[0074] The position of the outer circumferential portion 31f does not change in the radial direction throughout the entire axial direction of the rotation axis. Therefore, the distance from the rotation axis O to the outer circumferential portion 31f in the C cross-section is the same as the distance from the rotation axis O to the outer circumferential portion 31f in the B cross-section.

[0075] The position of the outer circumferential side tip 31c changes along the axial direction of the rotation axis. Therefore, the position of the outer circumferential side tip 31c changes in the C cross-section and the B cross-section. The outer circumferential side tip 31c in the C cross-section moves by a displacement angle θ in the circumferential direction with respect to the outer circumferential side tip 31c in the B cross-section.

[0076] The position of the outer circumferential side tip 31c does not change in the radial direction throughout the entire axial direction of the rotation axis. Therefore, the distance from the rotation axis O to the outer circumferential side tip 31c in the C cross-section is the same as the distance from the rotation axis O to the outer circumferential side tip 31c in the B cross-section.

[0077] The position of the inner circumferential side tip 31d changes along the axial direction of the rotation axis. Therefore, the position of the inner circumferential side tip 31d changes in the C cross-section and the B cross-section. The inner circumferential side tip 31d in the C cross-section moves by a displacement angle θ in the circumferential direction with respect to the inner circumferential side tip 31d in the B cross-section. The position of the virtual circumscribed circle 30a moves by a displacement angle θ in the circumferential direction in the C cross-section and the B cross-section.

[0078] The position of the inner circumferential side tip 31d does not change in the radial direction throughout the entire axial direction of the rotation axis. Therefore, the distance from the rotation axis O to the inner circumferential side tip 31d in the C cross-section is the same as the distance from the rotation axis O to the inner circumferential side tip 31d in the B cross-section.

[0079] The curvature of the pressure surface 31b does not change throughout the entire axial direction of the rotation axis. The curvature of the negative pressure surface 31a does not change throughout the entire axial direction of the rotation axis.

[0080] Here, on the suction side of the impeller 30, even when the air flow flows out from the blade 31 on the inner circumferential side, the air flow can be diffused. Thereby, the organized and rapid growth of the turbulence in the wake of the blade can be suppressed, and the noise can be suppressed.

[0081] <Modification Example> In the above embodiment, the period of change along the rotation axis direction is a waveform. However, the period of change along the rotation axis direction is not particularly limited to this. For example, as shown in FIG. 18, the period of change along the rotation axis direction may be a sawtooth shape.

Example

[0082] An air conditioner installed on the side wall of the room was prepared. Specifically, an air conditioner in which each of the fan blocks has blades of the shape (new shape) of Embodiment 1 and an air conditioner having blades of the conventional shape (conventional shape) were prepared. In each air conditioner, the wind speed (m / s) was measured at various axial positions (mm) at positions X and Y in FIG. 19. FIG. 20 shows the measurement results at position X. FIG. 21 shows the measurement results at position Y.

[0083] In both FIGS. 20 and 21, the turbulence of the wind speed is reduced in the new shape. That is, in the new shape, the noise is suppressed.

Example

[0084] An air conditioner installed on the side wall of the room was prepared. Specifically, an air conditioner in which each of the fan blocks has blades of the shape (new shape) of Embodiment 1 and an air conditioner having blades of the conventional shape (conventional shape) were prepared. The ratio H / L of the wave height H of the blade to the chord length L was changed, and the sound reduction amount (dBA) was measured for the case of a large air volume (air volume 22.3 m 3 / min) and the case of a small air volume (air volume 13 m 3 / min). Taking the sound reduction amount equivalent to that when using an air conditioner having blades of the conventional shape as 0 dBA, the results of the air conditioner having blades of the new shape are shown in FIG. 22.

[0085] In FIG. 22, when H / L is 0.041 or less, the sound reduction amount is a negative value in both the case of a large air volume and the case of a small air volume. That is, the noise is suppressed.

[0086] In FIG. 22, when H / L is between 0.006 and 0.034, the sound reduction amount is -0.3 dBA or less for both the large air volume and the small air volume. When H / L is between 0.008 and 0.033, the sound reduction amount is -0.4 dBA or less for both the large air volume and the small air volume.

Example

[0087] An air conditioner installed on the side wall of the room was prepared. Specifically, an air conditioner having blades of the shape (new shape) of Embodiment 1 for each of the fan blocks and an air conditioner having blades of the conventional shape (conventional shape) were prepared. By changing the ratio P / H of the wave interval P to the wave height H, the sound reduction amount (dBA) was measured for the case of a large air volume (air volume 22.3 m 3 / min) and the case of a small air volume (air volume 13 m 3 / min). The results are shown in FIG. 23. Taking the sound reduction amount equivalent to that when using an air conditioner having blades of the conventional shape as 0 dBA, the results of the air conditioner having blades of the new shape are shown in FIG. 23.

[0088] In FIG. 23, when P / H is between 0 and 39, the sound reduction amount is negative for the large air volume. That is, the noise is suppressed.

[0089] In FIG. 23, when P / H is between 7 and 31, the sound reduction amount is negative for both the large air volume and the small air volume.

[0090] As described above, although the embodiments of the present disclosure have been described, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure described in the claims.

Explanation of Signs

[0091] 10 Casing 20 Heat exchanger 30 Impeller 30a Virtual circle (virtual circumscribed circle) connecting the outer ends of the blades 31 Blade 31a Negative pressure surface 31b Pressure surface 31c Outer peripheral tip 31d Inner peripheral tip 31e Outer peripheral end on the pressure surface side 31f External connection part 90 Air conditioner 100 Air conditioning unit 101 Cross-flow fan Height of H wave L Chord length O Rotation axis θ Displacement angle θ2 Mounting angle

Prior art documents

Patent documents

[0092]

Patent Document 1

Claims

1. A cylindrical cross-flow fan (101) comprising a plurality of impellers (30) having a plurality of blades (31) arranged in the circumferential direction, wherein each blade has a negative pressure surface (31a) which is a curved surface arranged on the side opposite to the rotation direction and bulges in the direction opposite to the rotation direction, a pressure surface (31b) which is a curved surface arranged on the rotation direction side and recesses in the direction opposite to the rotation direction, and an outer peripheral side tip portion (31c) connecting the negative pressure surface and the pressure surface, and has the pressure surface and the outer peripheral side tip portion are connected at the pressure surface side outer peripheral end (31e), the negative pressure surface and the outer peripheral side tip portion are connected at an outer connection portion (31f) which is a portion where the outer peripheral side tip portion contacts the virtual circumscribed circle (30a) of the blade, the position of the pressure surface side outer peripheral end periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction, the position of the pressure surface side outer peripheral end passes through a circumferential recess position (C) which is recessed in the circumferential direction and a circumferential protrusion position (B) which protrudes in the circumferential direction in the circumferential direction change, the curvature of the pressure surface periodically changes following the position of the pressure surface side outer peripheral end on the outer peripheral side with respect to the center of the blade, the position of the pressure surface side outer peripheral end in the circumferential recess is located on the front side in the rotation direction with respect to the outer connection portion, a cross-flow fan.

2. A cylindrical cross-flow fan (101) comprising a plurality of impellers (30) having a plurality of blades (31) arranged in the circumferential direction, wherein each blade has a negative pressure surface (31a) which is a curved surface arranged on the side opposite to the rotation direction and bulges in the direction opposite to the rotation direction, a pressure surface (31b) which is a curved surface arranged on the rotation direction side and recesses in the direction opposite to the rotation direction, and an outer peripheral side tip portion (31c) connecting the negative pressure surface and the pressure surface on the outer peripheral side, and has the pressure surface and the outer peripheral side tip portion are connected at the pressure surface side outer peripheral end (31e), the negative pressure surface and the outer peripheral side tip portion are connected at an outer connection portion (31f) which is a portion where the outer peripheral side tip portion contacts the virtual circumscribed circle of the blade, the position of the outer peripheral side tip portion periodically repeats changes in the circumferential direction and changes in the rotation direction along the rotation axis direction, the position of the outer peripheral side tip portion passes through a circumferential recess position (C) which is recessed in the circumferential direction and a circumferential protrusion position (B) which protrudes in the circumferential direction in the circumferential direction change, the curvatures of the pressure surface and the negative pressure surface connected to the outer peripheral side tip portion periodically change following the outer peripheral side tip portion on the outer peripheral side with respect to the center of the blade, The position of the outer peripheral end on the pressure surface side in the circumferential concave portion is located on the front side in the rotational direction with respect to the circumscribed portion in the circumferential convex portion. The height of the unevenness in the circumferential direction on the pressure surface side is equal to the height of the unevenness in the circumferential direction on the negative pressure surface side. Cross-flow fan.

3. A cylindrical cross-flow fan (101) including a plurality of impellers (30) having a plurality of blades (31) arranged in the circumferential direction, Each blade, A negative pressure surface (31a) that is disposed on the side opposite to the rotational direction and is a curved surface that bulges in the direction opposite to the rotational direction, A pressure surface (31b) that is disposed on the rotational direction side and is a curved surface that depresses in the direction opposite to the rotational direction, An outer peripheral tip portion (31c) that connects the negative pressure surface and the pressure surface on the outer peripheral side, And has, The circumferential position of each blade cross-section in the rotational axis direction periodically repeats and changes along the rotational axis direction without changing the mounting angle of the blade. In a view in the rotational axis direction, a convex portion cross-section (B cross-section) that is a cross-section of a peak of the period and a concave portion cross-section (C cross-section) that is a cross-section of a valley of the period partially overlap. Cross-flow fan.

4. The blowing wind speed is uniform. The cross-flow fan according to any one of Claims 1 to 3.

5. The period of the change along the rotational axis direction is a waveform. The cross-flow fan according to any one of Claims 1 to 3.

6. The blade has an inner peripheral tip portion (31d) that connects the negative pressure surface and the pressure surface on the inner peripheral side. The ratio H / L of the height H of the wave and the chord length L that is the distance between the outer peripheral tip portion and the inner peripheral tip portion is 0.041 or less. The cross-flow fan according to Claim 5.

7. The blade has an inner peripheral tip portion that connects the negative pressure surface and the pressure surface on the inner peripheral side. The ratio H / L of the height H of the wave and the chord length L that is the distance between the outer peripheral tip portion and the inner peripheral tip portion is 0.006 to 0.

035. The cross-flow fan according to Claim 5.

8. The ratio P / H of the interval P between the waves and the height H of the wave is 0 to 39. The cross-flow fan according to Claim 5.

9. The ratio P / H of the interval P between the waves and the height H of the wave is 7 to 31. The cross-flow fan according to Claim 5.

10. Equipped with the cross-flow fan according to any one of Claims 1 to 3, Air conditioner.

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