Patent Application
20240376898
The present disclosure relates to a cross flow fan.
There is a known cross flow fan having a configuration in which each blade of a fan is, based on a pressure difference between the positive pressure surface and the negative pressure surface of the blade concerned, deformed into a shape in which the outer diameter end portion of the blade concerned varies in the axial direction (see Patent Literature 1, for example).
[PTL 1] JP 2008-157568 A
The object of the cross flow fan disclosed in Patent Literature 1 in this manner is that, by deforming the outer diameter end portion of the blade concerned toward the negative pressure surface based on the pressure difference between the positive pressure surface and the negative pressure surface of the blade, flow between blades is dispersed, thus reducing noise. However, when the outer edge of the blade is deformed toward the negative pressure surface, the exit angle of the blade on the outer circumferential side is increased. When the exit angle of the blade on the outer circumferential side is increased, in an inflow region where air flows into an impeller, separation of air flow is enlarged in areas between blades at positions close to a rear guide, the areas having a small inflow air volume. Accordingly, there is a possibility of worsening of noise across the whole fan or of generation of abnormal sounds. Further, when the exit angle of the blade on the outer circumferential side is increased, in an outflow region where air flows out from the inside of the impeller, the outflow angel of air flowing out from the area between the blades is increased and hence, an outflow toward the area upstream of a fan casing is likely to increase. Therefore, there is a possibility that a phenomenon occurs in which the air flow that flows out from the inside of the impeller does not direct toward the blowing-out side of the casing, but flows back toward the rear guide, resulting in a reduction in resistance to loss of speed.
The present disclosure has been made to solve such a problem. The object of the present disclosure is to provide a cross flow fan that can suppress a reduction in resistance to loss of speed, and that can achieve a reduction in fan input and a reduction in noise by enhancing fan efficiency.
A cross flow fan according to the present disclosure includes: a plurality of support members arranged at a predetermined interval in a direction of a rotation axis, the support members being formed in the shape of a circular or ring-shaped flat plate, and a plurality of blades provided between adjacent support members, located close to an outer circumference of the support member, and spaced apart in the circumferential direction, each of the blades having a positive pressure surface in a rotation direction and a negative pressure surface in a counter-rotation direction, the negative pressure surface of the blade having a convex part that bulges toward the counter-rotation direction, in a cross section perpendicular to the rotation axis, the convex part of the blade being located on an inner circumferential side of an outer edge of the blade concerned and on an outer circumferential side of an outermost circle of virtual circles tangent to both the negative pressure surface of the blade concerned and the positive pressure surface of the blade adjacent to the counter-rotational side of the blade concerned, the convex part and a portion of the negative pressure surface on the inner circumferential side of the convex part being connected by a straight part, and the straight part being a tangent to both the convex part and the portion of the negative pressure surface on the inner circumferential side of the convex part.
According to the cross flow fan according to the present disclosure, it is possible to obtain an advantageous effect that a reduction in resistance to loss of speed can be suppressed, and a reduction in fan input and a reduction in noise can be achieved by enhancing fan efficiency.
Modes for carrying out a cross flow fan according to the present disclosure will be described with reference to attached drawings. In the respective drawings, identical or corresponding components are given the same reference symbols, and the repeated description will be simplified or omitted when appropriate. In the description made hereinafter, for the sake of convenience, the positional relationship of respective structures may be expressed with reference to the states shown in the drawings. The present disclosure is not limited to the following embodiments, and respective embodiments may be freely combined, optional constitutional elements of the respective embodiments may be modified, or optional constitutional elements of the respective embodiments may be omitted without departing from the gist of the present disclosure.
An embodiment 1 of the present disclosure will be described with reference to
As an example of a refrigeration cycle device that includes the cross flow fan according to the present disclosure, a configuration example of the air-conditioning apparatus will be described. Examples of the refrigeration cycle device that includes the cross flow fan according to the present disclosure include, for example a showcase in addition to the air-conditioning apparatus. As will be described later, the air-conditioning apparatus a blowing has function of air. Accordingly, the air-conditioning apparatus described herein is also an example of a blowing device that includes the cross flow fan according to the present disclosure. Examples of the blowing device that includes the cross flow fan according to the present disclosure include a circulator and a tower fan in addition to the air-conditioning apparatus.
The air-conditioning apparatus being the refrigeration cycle device according to the present embodiment includes indoor equipment 1 shown in
The indoor equipment 1 and the outdoor equipment are connected with each other by refrigerant pipes not shown in the drawing. The indoor equipment 1 includes a cross flow fan 100 and a heat exchanger 14. The outdoor equipment includes an outdoor equipment fan, a heat exchanger, a compressor, an expansion valve, a four-way valve, and the like, none of these being shown in the drawing. The refrigerant pipes are provided between the heat exchanger 14 of the indoor equipment 1 and the heat exchanger (not shown in the drawing) of the outdoor equipment in a state that allows circulation. A refrigerant is sealed in the refrigerant pipes. An example of the refrigerant sealed in the refrigerant pipes includes difluoromethane (CH2F2:R32). The refrigerant pipes sequentially connect the heat exchanger 14 of the indoor equipment 1, and the four-way valve, the compressor, the heat exchanger, and the expansion valve of the outdoor equipment. Accordingly, a refrigerant circuit is formed in which a refrigerant circulates between the heat exchanger of the indoor equipment 1 and the heat exchanger of the outdoor equipment.
The compressor of the outdoor equipment is equipment that compresses a supplied refrigerant to increase the pressure and the temperature of the refrigerant. For the compressor, a rotary compressor, a scroll compressor, a reciprocating compressor, or the like may be used, for example. The expansion valve expands the refrigerant, condensed by the heat exchanger of the outdoor equipment, to reduce the pressure of the refrigerant.
The heat exchanger 14 of the indoor equipment 1 causes the refrigerant that flows into the heat exchanger 14 to exchange heat with air around the heat exchanger 14. The cross flow fan 100 blows air in such a way as to cause indoor air to pass through an area around the heat exchanger 14, thus promoting heat exchange between the refrigerant and air by the heat exchanger 14, and sending the air heated or cooled by the heat exchange into the room again. The heat exchanger of the outdoor equipment causes the refrigerant that flows into the heat exchanger to exchange heat with air around the heat exchanger. The outdoor equipment fan blows air in such a way as to cause outdoor air to pass through an area around the heat exchanger of the outdoor equipment, thus promoting heat exchange between the refrigerant and air by the heat exchanger.
In the refrigerant circuit having such a configuration, heat exchange between a refrigerant and air is performed in each of the heat exchanger 14 of the indoor equipment 1 and the heat exchanger of the outdoor equipment and hence, the refrigerant circuit serves as a heat pump that transfers heat between the indoor equipment 1 and the outdoor equipment. When the four-way valve is switched, a circulating direction of the refrigerant in the refrigerant circuit is reversed, so that a cooling operation and a heating operation of the air-conditioning apparatus can be switched.
As shown in
An air passage extending from the air inlet 11 to the air outlet 12 is formed in the housing 10. A filter 13 is installed in the air inlet 11. The filter 13 is provided to remove relatively large refuse, dust, dirt, and the like from air that flows into the housing 10 from the air inlet 11.
In the air passage in the housing 10, the heat exchanger 14 is installed on the downwind side of the filter 13. The heat exchanger 14 performs heat exchange with air flowing through the air passage in the housing 10, thus heating or cooling the air flowing through the air passage. Whether air is heated or cooled depends on whether the air-conditioning apparatus is performing a heating operation or a cooling operation.
In the above-described air passage, the cross flow fan 100 is installed on the downwind side of the heat exchanger 14. The cross flow fan 100 is provided to generate, in the air passage in the housing 10, an air flow directing to the air outlet 12 from the air inlet 11. In the housing 10, a rear guide 16 is provided on the rear surface side of an impeller of the cross flow fan 100. Further, in the housing 10, a side wall 15 is provided on the front surface side of the impeller of the cross flow fan 100.
The rear guide 16 is disposed to have a helical shape in which a distance from the impeller of the cross flow fan 100 increases as the rear guide 16 approaches the air outlet 12 from the heat exchanger 14. The side wall 15 disposed on the front surface side of the impeller of the cross flow fan 100 protrudes toward the rear surface side to have a tongue shape at a position on the air-outlet-12-side of the impeller. The rear guide 16 and the side wall 15 form the casing of the cross flow fan 100. The impeller of the cross flow fan 100 is housed in the casing of the cross flow fan 100. By providing such a casing, when the impeller of the cross flow fan 100 is rotated in a rotation direction R indicated by an arrow in the drawing, the following air flow is generated. That is, air is suctioned into areas between blades of the impeller from an area having the smallest flow passage resistance, that is, an area close to the heat exchanger 14. Then, the suctioned air flows in such a way as to penetrate through the impeller, and is blown out to an area having the second smallest flow passage resistance, that is, an area close to the air outlet 12.
A wind direction plate 17 is provided to the air outlet 12. The wind direction plate 17 is provided to adjust a blowing angle of air to be blown out from the air outlet 12.
When the cross flow fan 100 is operated, an air flow directing toward the air outlet 12 from the air inlet 11 is generated in the air passage, so that air is suctioned from the air inlet 11 and the air is blown out from the air outlet 12. The air suctioned from the air inlet 11 forms an air flow that passes through the filter 13, the heat exchanger 14, and the cross flow fan 100 in this order along the air passage in the housing 10, and is blown out from the air outlet 12. At this point of operation, the wind direction plate 17 disposed on the downwind side of the cross flow fan 100 adjusts a direction of air to be blown out from the air outlet 12, that is, the air blowing direction. The indoor equipment 1 of the air-conditioning apparatus having the above-mentioned configuration blows air into a room. The indoor equipment 1 can change the temperature and the direction of the air flow to be blown.
As shown in
The impeller 110 includes a plurality of support members 120. The support member 120 is a flat plate member having a circular shape or a ring shape. The plurality of support members 120 are arranged at predetermined intervals in a direction parallel to the rotation axis 140 (hereinafter also referred to as “direction of the rotation axis 140”). The rotation axis 140 of the impeller 110 is provided in such a way as to penetrate through the center of the circular shape or the ring shape of each of the plurality of support members 120. The plurality of blades 130 are provided between adjacent support members 120. The plurality of blades 130 are provided at a position close to the outer circumference of the support member 120. The plurality of blades 130 are aligned in a spaced-apart manner along the circumferential direction of the support member 120. The plurality of blades 130 supported between a pair of support members 120 form one series of blades. The impeller 110 of the cross flow fan 100 is formed of approximately seven to fourteen series of blades that are connected continuously in the direction of the rotation axis 140.
As shown in these drawings, each of the plurality of blades 130 has the positive pressure surface 131 and the negative pressure surface 132, and an outer edge 133 and an inner edge 134. The positive pressure surface 131 is the surface of the blade 130 that faces in the rotation direction. The negative pressure surface 132 is the surface of the blade 130 that faces in a direction opposite to the rotation direction (hereinafter also referred to as counter-rotation direction). The outer edge 133 is the end portion of the blade 130 that is farthest from the rotation axis 140. The inner edge 134 is the end portion of the blade 130 that is closest to the rotation axis 140.
The negative pressure surface 132 of each blade 130 has a convex part 161 that bulges toward the counter-rotation direction. The convex part 161 of the blade concerned 130a is located on the inner circumferential side of the outer edge 133 of the blade concerned 130a and on the outer circumferential side of an outermost virtual circle 20. In the cross section C, the convex part 161 of the blade concerned 130a and a portion of the negative pressure surface 132 of the blade concerned 130a on the inner circumferential side of the convex part 161 of the blade concerned 130a are connected by a straight part 162. In the cross section C, the straight part 162 is a tangent to both the convex part 161 and the portion of the negative pressure surface 132 on the inner circumferential side of the convex part 161. In the cross section C, “conventional blade” shown by a broken line in the drawing is shown by an arc that connects the outer edge 133 and the inner edge 134 with each other, and that overlaps with a portion of the negative pressure surface 132 on the inner circumferential side of the straight part 162. The convex part 161 according to the present disclosure is formed in such a way as to bulge toward the counter-rotation direction from such an arc.
Next, an advantageous effect obtained by the cross flow fan 100 having the above-mentioned configuration will be described while making a comparison with a comparison example shown in
In contrast, in the cross flow fan 100 according to the present disclosure, the convex part 161 is provided to the negative pressure surface 132 of the blade 130 and hence, it is possible to increase a blade thickness on the negative pressure surface 132 side at the portion of the blade 130 close to the outer circumferential side. By increasing the blade thickness on the negative pressure surface 132 side at the portion of the blade 130 close to the outer circumferential side, as shown in
The portion of the negative pressure surface 132 on the inner circumferential side and the convex part 161 are smoothly connected by the straight part 162 being a tangent to the portion of the negative pressure surface 132 on the inner circumferential side and to the convex part 161. Therefore, a flow between the blades 130 can smoothly flow from the outer circumferential side to the inner circumferential side in the inflow region, and can smoothly flow from the inner circumferential side to the outer circumferential side in the outflow region and hence, ventilation resistance between the blades 130 is reduced. Accordingly, it is possible to reduce the fan input, it is possible to reduce the fan input. Further, the convex part 161 is located on the inner circumferential side of the outer edge 133. Therefore, there is no possibility of an increase in exit angle of the blade 130, that is, installation angle on the outer circumferential side and hence, an outflow toward the area upstream of the casing is not increased, resulting in suppressing a reduction in resistance to loss of speed.
As described above, according to the cross flow fan 100 according to the present disclosure, the amount of separation of an air flow between the blades 130 is reduced while resistance to loss of speed is maintained and hence, the relative velocity between air flows in the space between the blades 130 is reduced. Accordingly, ventilation resistance is reduced, resulting in achieving a reduction in fan input. Further, the amount of separation of an air flow is reduced in the inflow region and hence, it is possible to reduce noise caused by separation at the front edge (the outer edge 133 on the inflow side) of the blade 130. Accordingly, it is possible to suppress a reduction in resistance to loss of speed, and it is also possible to achieve a reduction in fan input and a reduction in noise by enhancing fan efficiency.
In the cross flow fan 100 according to the present embodiment, the plurality of forming the above-described one series of blades of the impeller 110 may be arranged at equal pitches in the circumferential direction, or may be arranged at unequal pitches in the circumferential direction. Describing the case in other words in which the blades 130 are arranged at equal pitches in the circumferential direction, the blades 130 in one series of blades 130 have equal intervals in the circumferential direction. Describing the case in other words in which the blades 130 are arranged at unequal pitches in the circumferential direction is, the intervals of the blades 130 in the circumferential direction in one series of blades 130 have different distances.
In the case in which the blades 130 are arranged at unequal pitches in the circumferential direction, the blade thickness of each blade 130 at the convex part 161 may be varied corresponding to the pitch. As shown in
In an area between the blades 130 having a relatively small interval (pitch), although the amount of separation is small, a flow passage is narrow, so that pressure loss is likely to increase due to the convex part 161. In contrast, in an area between the blades 130 having a relatively large interval (pitch), although the amount of separation is large, a flow passage is wide, so that pressure loss is less likely to increase due to the convex part 161. In view of the above, the convex part 161 of the blade 130 having a small pitch is caused to have a small thickness, and the convex part 161 of the blade 130 having a large pitch is caused to have a large thickness. With such a configuration, it is possible to suppress an increase in pressure loss in the flow passage between the blades 130, and it is also possible to achieve a further reduction in fan input by reducing the amount of separation.
In the case in which the blades 130 are arranged at unequal pitches in the circumferential direction, in other words, in the case in which the intervals of the blades 1130 in the circumferential direction in one series of blades 130 have different distances, as shown in
Next, a modification of the cross flow fan 100 according to the present embodiment will be described with reference to
By causing each blade 130 to have the first regions 171, each provided with the convex part 161, and the second regions 172, having no convex part 161, in the width direction of the blade 130, that is, in the direction of the rotation axis 140 as described above, variations can be made to the relative velocity between air flows in the space between the blades 130 in the direction of the rotation axis 140 of the blade 130. Due to the variation in relative velocity between air flows in the space between the blades 130, turbulence is generated in the air flow and hence, the amount of separation of the air flow from the blade surface is reduced. Further, the relative velocity between the air flows in the space between the blades 130 is reduced and hence, pressure loss is reduced, resulting in achieving a further reduction in fan input.
In the case in which the blades 130 are molded by using a mold in the process of manufacturing the blades 130, generally, a so-called draft is formed in the direction of the rotation axis 140. Due to such a draft, the portion of the blade 130 at the inner edge 134 has inclination in the direction of the rotation axis 140. The portion of the blade 130 at the inner edge 134 has a thickness that gradually decreases from one side toward the other side in the direction of the rotation axis 140. In the example shown in
In such a case, it is sufficient to have a configuration in which the portion at the inner edge 134 that has a smaller thickness correspond to the first region 171, that is, the convex part 161, that has a larger width in the direction of the rotation axis 140. That is, in the example shown in
L1>L2>L3 (1)
At the portion at the inner edge 134 having a small thickness, an interval between the blade concerned 130a and the adjacent blade 130b is relatively large. In contrast, at the portion at the inner edge 134 having a large thickness, an interval between the blade concerned 130a and the adjacent blade 130b is relatively small. As described above, at the portion having a small interval of the blades 130, although the amount of separation is small, the flow passage is narrow, so that pressure loss is likely to increase due to the convex part 161. In contrast, at the portion having a large interval of the blades 130, although the amount of separation is large, a flow passage is wide, so that pressure loss is less likely to increase due to the convex part 161. In view of the above, in the modification shown in
The present disclosure is applicable to a cross flow fan that includes a plurality of support members arranged at predetermined intervals in the direction of a rotation axis, and a plurality of blades provided between adjacent support members, located close to an outer circumference of the support member, and spaced apart in the circumferential direction.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/042057 | 11/16/2021 | WO |
