Centrifugal fan and air conditioner

Abstract

A centrifugal fan according to the present disclosure comprises an impeller having a main plate and a side plate disposed apart at an interval in the direction of an axis of rotation, a plurality of blades disposed between the main plate and the side plate, and a partitioning plate dividing an air channel between the main plate and the side plate in the direction of the axis of rotation. An inlet is provided in the center of the side plate. In a cross section including the axis of rotation, the side plate is curved so as to convex toward the main plate. The side plate expands in diameter proceeding downstream. The partitioning plate is located at a shorter distance to the side plate than to the main plate. In a cross section including the axis of rotation, at least partially in the circumferential direction, the axial distance between the outer circumferential edge of the main plate and the outer circumferential edge of the partitioning plate is greater than the axial distance between the outer circumferential edge of the side plate and the outer circumferential edge of the partitioning plate, and the axial distance between the outer circumferential edge of the side plate and the outer circumferential edge of the partitioning plate is greater than the axial height of the side plate.

Description

Centrifugal fans and air conditioners

[0001] The present disclosure relates to a centrifugal fan and an air conditioner.

[0002] In conventional centrifugal fans, when airflow is drawn in along the axis of rotation, turned 90 degrees, and expelled in the radial direction, the airflow tends to be biased toward the main plate due to inertial force, and the airflow tends to separate at the blade surfaces and side plate on the side plate side.

[0003] Increasing the fan's blowing height can increase the air volume, but if the fan height is fixed and only the blowing height is increased, the side panels become flattened and the curvature on the inner periphery increases, making the airflow prone to separation and preventing the full effect of increasing air volume.

[0004] Japanese Patent Application Publication No. 2001-082384

[0005] By adding a partition plate as in Patent Document 1, the wind speed on the side panel side can be increased, but if the ratio of the height of the side panel to the axial height of the fan is small, the effect of increasing air volume cannot be fully achieved unless the partition plate is positioned appropriately.

[0006] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a centrifugal fan and an air conditioner that are advantageous in achieving a high air volume.

[0007] A centrifugal fan according to the present disclosure is a centrifugal fan equipped with an impeller having a main plate and side plates spaced apart in the direction of the rotation axis, a plurality of blades disposed between the main plate and the side plate, and a partition plate that divides an air passage between the main plate and the side plate in the direction of the rotation axis, wherein an air inlet is provided at the center of the side plate, and in a cross section including the rotation axis, the side plate is curved so as to be convex toward the main plate and the diameter of the side plate increases downstream, the partition plate is closer to the side plate than to the main plate, and in the cross section including the rotation axis, the axial distance between the outer peripheral edge of the main plate and the outer peripheral edge of the partition plate is greater than the axial distance between the outer peripheral edges of the side plate and the partition plate, and the axial distance between the outer peripheral edges of the side plate and the partition plate is greater than the axial height of the side plate. An air conditioner according to the present disclosure is equipped with the above-described centrifugal fan.

[0008] According to the present disclosure, it is possible to provide a centrifugal fan and an air conditioner that are advantageous in achieving a high air volume.

[0009] Fig. 1 is a cross-sectional view showing an impeller provided in the centrifugal fan according to embodiment 1. Fig. 2 is a cross-sectional view showing an impeller provided in the centrifugal fan according to embodiment 1. Fig. 3 is a cross-sectional view showing a modified example of the impeller provided in the centrifugal fan according to embodiment 1. Fig. 4 is a side view showing the impeller provided in the centrifugal fan according to embodiment 1. Fig. 5 is a plan view showing the impeller provided in the centrifugal fan according to embodiment 1. Fig. 6 is a diagram showing the configuration of an air conditioning apparatus according to embodiment 1. Fig. 7 is a perspective view showing the impeller provided in the centrifugal fan according to embodiment 2.

[0010] Hereinafter, embodiments will be described with reference to the drawings. Common or corresponding elements in each drawing are designated by the same reference numerals, and descriptions thereof will be simplified or omitted. Note that when angles are mentioned in this disclosure, if there is a reflex angle and a minor angle whose sum is 360 degrees, this generally refers to the minor angle, and if there is an acute angle and an obtuse angle whose sum is 180 degrees, this generally refers to the acute angle. The configurations shown in the following embodiments are examples of the technical ideas of the present disclosure, and may be combined with other known technologies or multiple technical ideas described in the present disclosure. Furthermore, parts of the configuration may be omitted or modified without departing from the spirit of the present disclosure.

[0011] Embodiment 1. Figure 1 is a cross-sectional view showing an impeller 1 included in a centrifugal fan according to embodiment 1. The centrifugal fan of this embodiment includes the impeller 1 shown in Figure 1, a motor (not shown) that rotates the impeller 1, and a housing (not shown) that houses the impeller 1. Figure 1 shows a cross section including the rotation axis R of the impeller 1.

[0012] The impeller 1 has a main plate 2 and a side plate 3 arranged at a distance from each other in the direction of the rotation axis R, a plurality of blades 4 arranged between the main plate 2 and the side plate 3, and a partition plate 5 that divides the air passage between the main plate 2 and the side plate 3 in the direction of the rotation axis R.

[0013] The main plate 2 has a boss portion fixed to the motor shaft. The main plate 2 is a disk-shaped member with a central portion including the boss portion raised in a mountain shape. An air outlet is provided between the radially outer peripheral end of the main plate 2 and the radially outer peripheral end of the side plate 3.

[0014] The side plate 3 is an annular member. An intake port is provided in the center of the side plate 3. In a cross section including the rotation axis R, the side plate 3 is curved so as to be convex toward the main plate 2. The diameter of the side plate 3 increases toward the downstream side.

[0015] The partition plate 5 is located closer to the side plate 3 than to the main plate 2. The two air passages divided by the partition plate 5 are arranged next to each other in the direction of the rotation axis R.

[0016] The axial distance between the outer peripheral edge of the main plate 2 and the outer peripheral edge of the partition plate 5 is defined as D1. The axial distance between the outer peripheral edge of the side plate 3 and the outer peripheral edge of the partition plate 5 is defined as D2. The axial height of the side plate 3 is defined as D3. In a cross section including the rotation axis R, the relationship D1 > D2 > D3 is satisfied at least partially in the circumferential direction.

[0017] This embodiment provides the following advantages. It is possible to ensure a high ratio of the fan's blowing height D4 to the total axial height of the impeller 1 while preventing airflow separation on the surfaces of the blades 4, the side plates 3, and the partition plate 5, thereby achieving a high airflow rate. The rotation speed can be reduced to obtain the same airflow rate, resulting in a lower noise level. Furthermore, the enlarged blowing area reduces the wind speed, thereby reducing losses and reducing the fan motor input. Since the axial distance D2 between the outer circumferential edge of the side plates 3 and the outer circumferential edge of the partition plate 5 is smaller than the axial distance D1 between the outer circumferential edge of the main plate 2 and the outer circumferential edge of the partition plate 5, the airflow that flows into the impeller 1 easily follows the side plates 3, making it less likely for airflow separation to occur.

[0018] The centrifugal fan's intake port is equipped with a bellmouth (not shown) that guides the airflow entering the fan. The bellmouth is installed, for example, to separate an upstream space located between the indoor unit's intake port and the centrifugal fan's intake port from a downstream space located between the centrifugal fan's outlet and the indoor unit's outlet. The bellmouth and centrifugal fan overlap in the axial direction, with a fan gap spaced a predetermined distance apart in the radial direction.

[0019] The trailing edge of the blade 4 is located in the opposite direction of rotation to the leading edge. In a cross section including the rotation axis R, the inner circumferential end of the partition plate 5 is located closer to the rotation axis R than the downstream end of the bell mouth. Furthermore, the inner circumferential end of the partition plate 5 is located closer to the rotation axis R than the inner circumferential end of the blade 4 at the connection portion with the blade 4.

[0020] The inner peripheral side of the partition plate 5 is curved so as to convex toward the main plate 2, facing the suction port. The curvature of the curved portion decreases toward the outer periphery. The angle between the tangent at the inner peripheral end of the partition plate 5 and the rotation axis R is preferably greater than 0 degrees and less than 30 degrees. This angle may vary in the circumferential direction.

[0021] In the direction of the rotation axis, the downstream end of the bell mouth is located between the inner peripheral end of the partition plate 5 and the upstream end of the side plate 3.

[0022] The distance between the side plate 3 and the partition plate 5 in the direction perpendicular to the side plate 3 may be gradually reduced from the upstream end toward the downstream end. In this way, the flow between the side plate 3 and the partition plate 5 becomes a contracted flow and is stabilized, thereby more reliably preventing separation of the airflow.

[0023] When the axial height D3 of the side plate 3 with respect to the overall height of the impeller 1 is less than 15%, it is desirable that the axial distance D2 between the outer peripheral edge of the side plate 3 and the outer peripheral edge of the partition plate 5 with respect to the overall height of the impeller 1 be 15% or more and 25% or less. This effectively suppresses airflow separation on the surfaces of the side plate 3 and the blades 4 near the side plate 3. It is also desirable that the axial height D3 of the side plate 3 with respect to the overall height of the impeller 1 be 10% or more. It is also desirable that the axial distance D2 between the outer peripheral edge of the side plate 3 and the outer peripheral edge of the partition plate 5 with respect to the overall height of the impeller 1 be more than 20%.

[0024] Figure 2 is a cross-sectional view showing the impeller 1 included in the centrifugal fan according to embodiment 1. As shown in Figure 2, in a cross section including the rotation axis R, the extension direction from the outer circumferential edge of the side plate 3 and the extension direction from the outer circumferential edge of the partition plate 5 are parallel to each other. This allows the blowing direction near the side plate 3 to be aligned with the blowing direction near the partition plate 5, more reliably preventing an increase in pressure loss due to a sudden contraction of the flow and airflow separation between the side plate 3 and the partition plate 5. The extension direction is the tangential direction.

[0025] Figure 3 is a cross-sectional view showing a modified example of the impeller 1 included in the centrifugal fan according to embodiment 1. As shown in Figure 3, in the impeller 1 of the modified example, in a cross section including the rotation axis R, the extension direction from the outer circumferential edge of the side plate 3 and the extension direction from the outer circumferential edge of the partition plate 5 are inclined away from the main plate 2, i.e., toward the suction side, with respect to a direction perpendicular to the rotation axis R. This causes the airflow from the impeller 1 to expand in the height direction, restoring static pressure and achieving a high airflow rate.

[0026] 3, in a cross section including the rotation axis R, the direction extending from the outer peripheral edge of the partition plate 5 has a larger inclination angle than the direction extending from the outer peripheral edge of the side plate 3. Since airflow is more likely to separate from the partition plate 5 near the side plate 3, by tilting the direction extending from the outer peripheral edge of the partition plate 5 further toward the suction side, airflow separation near the side plate 3 can be more reliably prevented.

[0027] FIG. 4 is a side view showing the impeller 1 included in the centrifugal fan according to the first embodiment. As shown in FIG. 4 , the outer peripheral edge 6 of the partition plate 5 is located on the pressure side that receives the positive pressure of the blades 4. The outer peripheral edge 7 of the partition plate 5 is located on the suction side that receives the negative pressure of the blades 4. As shown in FIG. 4 , the axial distance between the outer peripheral edge of the side plate 3 and the outer peripheral edge of the partition plate 5 is non-uniform along the circumferential direction. That is, the axial position of the outer peripheral edge of at least one of the side plate 3 or the partition plate 5 is non-uniform along the circumferential direction. Because the airflow speed between the side plate 3 and the partition plate 5 varies circumferentially, making the axial distance non-uniform in accordance with the wind speed reduces the wind speed and reduces losses.

[0028] In the example shown in Figure 4, the axial distance between the outer peripheral edge of the side plate 3 and the outer peripheral edge of the partition plate 5 is greater nearer to the part of the blade 4 that receives negative pressure than nearer to the part that receives positive pressure of the blade 4. That is, the distance between the outer peripheral edge of the side plate 3 and the outer peripheral edge 7 of the partition plate 5 is greater than the distance between the outer peripheral edge of the side plate 3 and the outer peripheral edge 6 of the partition plate 5. The blade surface facing the counter-rotation direction near the side plate 3, i.e., the blade suction surface, is more likely to experience airflow separation from the blade surface facing the rotation direction, i.e., the blade pressure surface. For this reason, increasing the distance between the partition plate 5 and the side plate 3 and promoting inflow can more reliably prevent airflow separation.

[0029] FIG. 5 is a plan view showing the impeller 1 included in the centrifugal fan according to the first embodiment. FIG. 5 is a top view with the side plate 3 removed. As shown in FIG. 5, the blades 4 have blade pressure surfaces 8 that receive positive pressure and blade suction surfaces 9 that receive negative pressure. In the example shown in FIG. 5, the distance from the rotation axis R to the inner circumferential end of the partition plate 5 is non-uniform along the circumferential direction. Because the airflow between the side plate 3 and the partition plate 5 has different wind speeds along the circumferential direction, changing the position of the inner circumferential end of the partition plate 5 in accordance with the wind speed and changing the airflow flowing between the side plate 3 and the partition plate 5 reduces the wind speed and reduces losses.

[0030] 5 , the distance D6 from the rotation axis R to the inner circumferential edge 11 of the partition plate 5 at the portion of the blade 4 that receives positive pressure is greater than the distance D5 from the rotation axis R to the inner circumferential edge 10 of the partition plate 5 at the portion of the blade 4 that receives negative pressure. The wind speed is higher on the blade pressure surface 8 side, which is the blade surface in the direction of rotation, than on the blade suction surface 9, which is the blade surface in the counter-rotation direction. In contrast, by increasing the distance D6 from the rotation axis R to the inner circumferential edge 11 of the partition plate 5 on the blade pressure surface 8 side, the airflow that flows between the side plate 3 and the partition plate 5 is reduced, and the wind speed is lowered, thereby reducing losses.

[0031] FIG. 6 is a diagram showing the configuration of an air conditioner according to the first embodiment. A centrifugal fan configured as described above can be used in an air conditioner. The air conditioner according to this embodiment includes an indoor unit 200 having a centrifugal fan 202 according to this embodiment, and an outdoor unit 100. The indoor unit 200 is installed inside a room to be air-conditioned, i.e., inside the room. The outdoor unit 100 is installed outside the room, i.e., outdoors. The indoor unit 200 includes an indoor heat exchanger 201 that is blown by the centrifugal fan 202. The outdoor unit 100 includes an outdoor heat exchanger 103, an outdoor blower 104, a compressor 101, an expansion valve 105, and a four-way valve 102.

[0032] The indoor unit 200 and the outdoor unit 100 are connected by a gas pipe 300 and a liquid pipe 400. The gas pipe 300 connects the four-way valve 102 to the indoor heat exchanger 201. The liquid pipe 400 connects the expansion valve 105 to the indoor heat exchanger 201. Refrigerant is sealed in the gas pipe 300 and the liquid pipe 400. The gas pipe 300 and the liquid pipe 400 connect the indoor heat exchanger 201, the four-way valve 102, the compressor 101, the outdoor heat exchanger 103, and the expansion valve 105 in a ring shape.

[0033] The compressor 101 is a device that compresses the supplied refrigerant to increase the pressure and temperature of the refrigerant. The expansion valve 105 expands the refrigerant condensed in the outdoor heat exchanger 103 to reduce the pressure of the refrigerant.

[0034] The indoor heat exchanger 201 exchanges heat between the refrigerant that has flowed into the indoor heat exchanger 201 and the air surrounding the indoor heat exchanger 201. The centrifugal fan 202 blows indoor air so that it passes around the indoor heat exchanger 201, promoting heat exchange between the refrigerant and the air in the indoor heat exchanger 201, and sends the air that has been heated or cooled by the heat exchange back into the room. The outdoor heat exchanger 103 exchanges heat between the refrigerant that has flowed into the outdoor heat exchanger 103 and the air surrounding the outdoor heat exchanger 103. The outdoor blower 104 blows outdoor air so that it passes around the outdoor heat exchanger 103, promoting heat exchange between the refrigerant and the air in the outdoor heat exchanger 103.

[0035] In the example of FIG. 6, an example in which the centrifugal fan of this embodiment is applied to the indoor unit 200 has been described, but the centrifugal fan of this embodiment may also be applied to the outdoor unit 100.

[0036] Second Embodiment Next, a second embodiment will be described with reference to Fig. 7, focusing on differences from the first embodiment described above, and explanations of commonalities will be simplified or omitted. Elements common to or corresponding to the elements described above will be denoted by the same reference numerals.

[0037] Fig. 7 is a perspective view showing an impeller included in a centrifugal fan according to embodiment 2. As shown in Fig. 7, a centrifugal fan 12 according to this embodiment has a plurality of first blades 13 between the main plate 2 and the partition plate 5, and a plurality of second blades 14 between the partition plate 5 and the side plate 3. The first blades 13 and the second blades 14 may be arranged with a circumferential offset. The number of first blades 13 and the number of second blades 14 may be different.

[0038] Of the features of the above-described multiple embodiments, two or more features that can be combined may be combined and implemented.

[0039] REFERENCE SIGNS LIST 1 impeller, 2 main plate, 3 side plate, 4 blade, 5 partition plate, 6 outer peripheral edge, 7 outer peripheral edge, 8 blade pressure surface, 9 blade suction surface, 10 inner peripheral edge, 11 inner peripheral edge, 12 centrifugal fan, 13 first blade, 14 second blade, 100 outdoor unit, 101 compressor, 102 four-way valve, 103 outdoor heat exchanger, 104 outdoor blower, 105 expansion valve, 200 indoor unit, 201 indoor heat exchanger, 202 centrifugal fan, 300 gas piping, 400 liquid piping

Claims

1. A centrifugal fan comprising an impeller having a main plate and a side plate arranged at intervals in the direction of a rotation axis, a plurality of blades arranged between the main plate and the side plate, and a partition plate that divides an air passage between the main plate and the side plate in the direction of the rotation axis, wherein a suction port is provided at the center of the side plate, in a cross section including the rotation axis, the side plate is curved so as to bulge toward the main plate, the diameter of the side plate expands toward the downstream, the partition plate is located at a position closer to the side plate than the main plate, and in a cross section including the rotation axis, at least partially in the circumferential direction, an axial distance between an outer peripheral end of the main plate and an outer peripheral end of the partition plate is greater than an axial distance between an outer peripheral end of the side plate and the outer peripheral end of the partition plate, and the axial distance between the outer peripheral end of the side plate and the outer peripheral end of the partition plate is greater than an axial height of the side plate.

2. The centrifugal fan according to claim 1, wherein a distance between the side plate and the partition plate in a direction perpendicular to the side plate gradually decreases from the upstream end toward the downstream end.

3. The centrifugal fan according to claim 1 or claim 2, wherein in a cross section including the rotation axis, an extension direction from an outer peripheral end of the side plate and an extension direction from an outer peripheral end of the partition plate are parallel to each other.

4. The centrifugal fan according to any one of claims 1 to 3, wherein in a cross section including the rotation axis, an extension direction from an outer peripheral end of the side plate and an extension direction from an outer peripheral end of the partition plate are inclined to the side opposite to the main plate with respect to a direction perpendicular to the rotation axis.

5. The centrifugal fan according to claim 4, wherein in a cross section including the rotation axis, an extension direction from an outer peripheral end of the partition plate has a larger inclination angle than an extension direction from an outer peripheral end of the side plate.

6. The centrifugal fan according to any one of claims 1 to 5, wherein an axial distance between an outer peripheral end of the side plate and an outer peripheral end of the partition plate is non-uniform along the circumferential direction.

7. The centrifugal fan according to any one of claims 1 to 6, wherein an axial distance between an outer peripheral end of the side plate and an outer peripheral end of the partition plate is non-uniform along the circumferential direction, and the axial distance is larger closer to a portion of the blade that receives negative pressure than to a portion of the blade that receives positive pressure.

8. The centrifugal fan according to any one of claims 1 to 7, wherein a distance from the rotation axis to an inner peripheral end of the partition plate is non-uniform along the circumferential direction.

9. The distance from the rotation axis to the inner peripheral end of the partition plate is non-uniform along the circumferential direction, and the distance from the rotation axis to the inner peripheral end of the partition plate is larger for the portion of the blade that receives positive pressure than for the portion of the blade that receives negative pressure. The centrifugal fan according to any one of claims 1 to 8.

10. An air conditioner comprising the centrifugal fan according to any one of claims 1 to 9.

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