Patent Application
20210003142
The present invention relates to a propeller fan that includes blades, and an air-sending device and a refrigeration cycle apparatus that include the propeller fan.
In the past, some blade shapes of propeller fans have been proposed as shapes for achieving low noise and a high efficiency of air-sending devices. The noise and energy loss of air-sending devices are made by the turbulence of airflow, for example, vortexes. For example, a fan motor that drives a propeller fan and is provided on an upstream side and an inner peripheral side of the propeller fan disturbs airflow toward a blade at the propeller fan. As a result, on an inner peripheral side of the blade, the airflow does not move along the blade and is easily disturbed, and vortexes are easily generated.
In view of this, blade shapes for reducing the turbulence of the airflow and generation of vortexes have been proposed. For example, Patent Literature 1 discloses that an inner part of a trailing edge of a blade is cut, and a protrusion portion that protrudes in the opposite direction to a rotation direction of the blade is provided at the trailing edge to increase the area of the blade and to increase a static pressure to a higher level.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2015-190332
In the propeller fan disclosed in Patent Literature 1, the inner peripheral side of the trailing edge of the blade extends along the flow direction of blown air, and the axis of vortexes generated at the trailing is parallel to the flow direction of airflow that passes over a blade surface. Therefore, vortexes developed over the blade surface from a leading edge join vortexes generated at the trailing edge, and remain until the air flows on a downstream side after being blown.
The present invention has been made to solve the above problem and provides a propeller fan in which the strength of vortexes generated at a trailing edge of a blade can be reduced, an air-sending device provided with the propeller fan, and a refrigeration cycle apparatus provided with the propeller fan.
A propeller fan according to an embodiment of the present invention includes a shaft provided on a rotation axis of the propeller fan, and a blade provided on an outer peripheral side of the shaft. The blade has a trailing edge on a rear side of the blade in a rotation direction of the propeller fan. The trailing edge includes a first trailing edge located on an innermost side of the trailing edge, and a second trailing edge adjacent to and outward of the first trailing edge. Where an innermost point of the first trailing edge is a first connection point, a connection point between the first trailing edge and the second trailing edge is a second connection point, and a straight line that extends through the rotation axis and the first connection point is a reference line, the second connection point is located forward of the reference line in the rotation direction, or located on the reference line, and the second trailing edge is located rearward of the second connection point in the rotation direction.
In the propeller fan according to the embodiment of the present invention, the second connection point is located forward of the reference line in the rotation direction, or located on the reference line, and the second trailing edge is located rearward of the second connection point in the rotation direction. Thus, vortexes generated at the first trailing edge and vortexes generated at the second trailing edge weaken each other. It is therefore possible to reduce the strength of the vortexes generated at the trailing edge of each blade.
Propeller fans according to Embodiment 1 to Embodiment 6 of the present invention will hereinafter be described with reference to the drawings. In the drawings, like reference signs designate like or corresponding components.
As illustrated in
The boss 3 corresponds to “shaft” in the present invention.
In the figures, an arrow RD indicates a rotation direction RD of the propeller fan 1, and an arrow FD indicates a flow direction FD of airflow. In Embodiment 1, the number of the blades 5 is three, but it is not limited to three.
Each of the blades 5 includes a leading edge 7, a trailing edge 9, an outer peripheral edge 11, and an inner peripheral edge 13. The leading edge 7 is formed as a front edge in the rotation direction RD. That is, the leading edge 7 is located on a front side of each blade 5 in the rotation direction RD. The trailing edge 9 is formed as a rear edge in the rotation direction RD. That is, the trailing edge 9 is located on a rear side of each blade 5 in the rotation direction RD. The inner peripheral edge 13 arcuately extends between innermost part of the leading edge 7 and innermost part of the trailing edge 9. Each blade 5 is connected to the outer peripheral side of the boss 3 at the inner peripheral edge 13. The outer peripheral edge 11 arcuately extends to connect outermost part of the leading edge 7 and outermost part of the trailing edge 9. For example, the radius of a circle whose center is located on the rotation axis CL and which passes through the outer peripheral edge 11 is constant. In the figures, arrows 8 indicate flows of air that flows to the pressure surface of each blade 5 when the propeller fan 1 is rotated.
With respect to Embodiment 1, it is described by way of example that the radius of the circle that passes through the outer peripheral edge 11 is constant. However, the shape of the outer peripheral edge 11 is not limited to such a shape. The shape of the outer peripheral edge 11 can be freely determined.
The configuration of the trailing edge 9 will now be described in detail.
As illustrated in
A connection point between the boss 3 and the first trailing edge 9a will be referred to as a first connection point P1. That is, the first connection point P1 is an innermost point of the first trailing edge 9a. A connection point between the first trailing edge 9a and the second trailing edge 9b will be referred to a second connection point P2. A straight line that extends through the rotation axis CL and the first connection point P1 will be referred to as a reference line BL.
The trailing edge 9 of each blade 5 is formed such that the second connection point P2 is located forward of the reference line BL in the rotation direction RD. Also, in the formed trailing edge 9, the second trailing edge 9b is located rearward of the second connection point P2 in the rotation direction RD. Furthermore, in the formed training edge 9, the first trailing edge 9a is located forward of the reference line BL in the rotation direction RD. That is, the first trailing edge 9a extends forward from the first connection point P1 to the second connection point P2 in the rotation direction RD. The second trailing edge 9b extends rearward from the second connection point P2 in the rotation direction RD.
As indicated in
Rh=(Ro−Ri)/2 [Formula 1]
In the above case, the trailing edge 9 of each blade 5 is formed such that the radius Rp of the circle whose center is located on the rotation axis CL and which passes through the second connection point P2 is smaller than the radius Rh that is half the difference between the radius Ro and the radius Ri.
As indicated in
In the above case, the trailing edge 9 of each blade 5 is formed such that the length L1 of the first trailing edge 9a is greater than or equal to the length L2 of the second trailing edge 9b. For example, the length L1 of the first trailing edge 9a of the trailing edge 9 is not more than twice the length L2 of the second trailing edge 9b. The length L1 of the first trailing edge 9a may be nearly equal to the length L2 of the second trailing edge 9b.
The operation of the propeller fan 1 according to Embodiment 1 will be described.
As illustrated in
The flow of air that flows to an inner peripheral side of a blade 5 that is close to the boss 3 will be described.
The boss 3 and the fan motor 61 are located upstream of the inner peripheral side of the blade 5, the boss 3 being cylindrically formed. Thus, just before air flows through the leading edge 7 of the blade 5, the flow of the air contains turbulent flow 21. For example, the turbulent flow 21 is generated by a vortex that is generated when the fluid passes through the fan motor 61 or the boss 3. For example, the turbulent flow 21 is generated because a wind speed is locally increased when a fluid passes through a flow passage that is narrowed due to provision of the fan motor 61, that of the boss 3, or generation of the vortex.
As illustrated in
As illustrated in
Therefore, a vortex Y that flows away from the first trailing edge 9a and a vortex Y that flows away from the second trailing edge 9b collide with each other, and these vortexes Y are weakened by friction between airflows that form the vortexes Y. Also, the vortexes Y that flow away from the first trailing edge 9a and the second trailing edge 9b are further greatly twisted and the curvature of the axis 36 increases as the vortexes Y flow more downstream, and the airflows that form the vortexes Y more easily collide with each other and the vortexes Y are further greatly weakened as the vortexes Y flow more downstream.
The axis 36X of vortexes X that flow over the blade surface of the blade 5 intersects the axis 36Y of vortexes Y at the trailing edge 9. Thus, the vortexes Y that flow away from the first trailing edge 9a and the second trailing edge 9b collide with the vortexes X, and the vortexes Y and the vortexes X are weakened by friction between the airflow that forms the vortexes Y and the airflow that forms the vortexes X.
In Embodiment 1, as described above, the trailing edge 9 of the blade 5 includes the first trailing edge 9a adjacent to the boss 3 and the second trailing edge 9b adjacent to the first trailing edge 9a. The second connection point P2 is more forward than the reference line BL in the rotation direction RD, and the second trailing edge 9b is more rearward than the second connection point P2 in the rotation direction RD.
Therefore, vortexes Y generated at the trailing edge 9 of the blade 5 flow away therefrom while having a curved axis 36Y and are weakened by friction therebetween. Furthermore, vortexes X having the axis 36X are generated at the leading edge 7 of the blade 5 and join on a downstream side, the vortexes Y generated at the trailing edge 9 of the blade 5, and the vortexes X and the vortexes Y are weakened by friction therebetween. Thus, the turbulence of the airflow is reduced, and the energy loss is also reduced. Furthermore, it is possible to achieve a propeller fan in which the turbulence of airflow that is caused by vortexes X and Y is reduced and noise is reduced.
In the following description, the advantages of the propeller fan 1 according to Embodiment 1 are described while referring to the comparison between the propeller fan of Embodiment 1 and those of comparative examples. In the following description of propeller fans of the comparative examples, components that are the same as or equivalent to those of the propeller fan 1 according to Embodiment 1 will be denoted by the same reference signs.
As illustrated in
Therefore, in the propeller fan of comparative example 1, the direction of the axis 36X of vortexes X that have flowed over the blade surface is the same as that of the axis 36Y of vortexes Y generated at the trailing edge 9. Therefore, the vortexes Y and the vortexes X do not cancel each other, and remain on a downstream side, thus causing an energy loss. In addition, noise is made by the turbulence of airflows that form the vortexes X and the vortexes Y.
By contrast, in the propeller fan 1 according to Embodiment 1, the axis 36X of the vortexes X and the axis 36Y of the vortexes Y intersect each other at the trailing edge 9. Therefore, it is possible to obtain the above advantages.
In the propeller fan 1 of comparative example 2, as illustrated in
Therefore, in the propeller fan of comparative example 2, on the inner peripheral side of the blade 5, vortexes Y are generated to have an axis 36Y that is curved in the opposite direction to the rotation direction RD and along the first trailing edge 9a and the second trailing edge 9b. Consequently, vortexes Y that have flowed away from the first trailing edge 9a and vortexes Y that have flowed away from the second trailing edge 9b are separated from each other, and airflows that form those vortexes Y thus do not collide with each other. Therefore, the vortexes Y are not weakened.
By contrast, in the propeller fan 1 according to Embodiment 1, vortexes Y that have flowed away from the first trailing edge 9a and vortexes Y that have flowed away from the second trailing edge 9b collide with each other. Therefore, it is possible to obtain the above advantages.
The shapes as illustrated in each of
As illustrated in
Therefore, in the propeller fan of comparative example 3, the vortexes Y that flow away from the first trailing edge 9a and the vortexes Y that flow away from the second trailing edge 9b do not easily collide with each other, as a result of which they are not easily weakened by each other.
By contrast, in the propeller fan 1 according to Embodiment 1, vortexes Y that have flowed away from the first trailing edge 9a and vortexes Y that have flowed away from the second trailing edge 9b collide with each other Therefore, it is possible to obtain the same advantages.
A propeller fan 1 according to Embodiment 2 will be described by referring mainly to the differences between Embodiments 1 and 2. Components that are the same as those in Embodiment 1 will be denoted by the same reference signs, and their descriptions will thus be omitted.
As illustrated in
As illustrated in
Because of the above configuration, vortexes Y that have flowed away from the first trailing edge 9a and vortexes Y that have flowed away from the second trailing edge 9b collide with each other, and are thus weakened by friction between airflows that form those vortexes Y as in Embodiment 1. As the vortexes Y that have flowed away from the first trailing edge 9a and the second trailing edge 9b moves further downstream, the vortexes Y are further twisted, and the curvature of the axis 36Y increases, and on the other hand, as the vortexes Y moves further downstream, the airflows that form the vortexes Y more easily collide with each other, and the vortexes Y are weakened.
Furthermore, the axis 36X of the vortexes X that have flowed over the blade surface of the blade 5 intersects the axis 36Y of the vortexes Y at the trailing edge 9. Therefore, the vortexes Y that have flowed away from the first trailing edge 9a and the second trailing edge 9b collide with the vortexes X, and the vortexes Y and the vortexes X are weakened by friction between the airflows that form the vortexes Y and the vortexes X.
A propeller fan 1 according to Embodiment 3 will be described by referring mainly to the differences between Embodiment 3 and Embodiments 1 and 2. Components that are the same as those in Embodiments 1 and 2 will be denoted by the same reference signs, and their descriptions will thus be omitted.
The shape as illustrated in
As indicated in
In the above case, the boss 3 is formed such that the distance Db between the rotation axis CL and the first connection point P1 to greater than the distance Df between the rotation axis CL and the third connection point P4. In other words, each blade 5 is formed such that a distance Dwf that is the distance between the third connection point P4 and the outer peripheral edge 11 is greater than a distance Dwb that is the distance between the first connection point P1 and the outer peripheral edge 11. That is, a side wall of the boss 3 is formed such that the trailing edge 9 is located outward of the leading edge 7 in the radial direction.
As illustrated in
Thus, the vortexes X that pass over the blade surface flows through a narrower region and thus flow at a higher speed as the vortexes X approaches the trailing edge. That is, the vortexes X collide with the vortexes Y generated at the trailing edge 9 at a higher speed, thus further effectively weakening the vortexes Y generated at the trailing edge 9.
Therefore, the turbulence of the airflow is further reduced, as compared with Embodiment 1, and the energy loss is further reduced. Furthermore, it is possible to provide a propeller fan in which the turbulence of the airflows that is caused by the vortexes X and Y can be further reduced and noise can be further reduced, as compared with that of Embodiment 1.
A propeller fan 1 according to Embodiment 4 will be described by referring mainly to the differences between Embodiment 4 and Embodiments 1 to 3. Components that are the same as those in Embodiments 1 to 3 will be denoted by the same reference signs, and their descriptions will thus be omitted.
The shape as illustrated in
The shape as illustrated in
As illustrated in
In the above case, each blade 5 is formed such that the first middle point P5 is located upstream of the second middle point P6 in a direction along the rotation axis CL (see
Since each blade 5 is a rearward inclined blade, it is thus formed such that it is moved to push air inwardly in the radial direction. It is therefore possible to reduce airflow 8 that moves away from the outer peripheral edge 11, and reduce the turbulence of the airflow 8.
Furthermore, since the airflow 8 is airflow toward the inner peripheral side of each blade 5, even if vortexes X generated on the inner peripheral side and the airflow 8 are mixed with each other, the vortexes X and the airflow 8 mixed with each other and vortexes Y generated on the inner peripheral side of the trailing edge 9 of each blade 5 can weaken each other. Therefore, even in the case where rearward inclined blades are employed as blades 5, it is possible to achieve a propeller fan in which the turbulence of the airflow, the energy loss, and the noise are all reduced.
A propeller fan 1 according to Embodiment 5 will be described by referring mainly to the differences between Embodiment 5 and Embodiments 1 to 4. Components that are the same as those in Embodiments 1 to 4 will be denoted by the same reference signs, and their descriptions will thus be omitted.
The shape as illustrated in
As illustrated in
The shaft 4 is rotated around the rotation axis CL. The joints 10 are each formed in the shape of, for example, a plate, and are adjacent to each other and disposed around the shaft 4. Each joint 10 joins the trailing edge 9 of a forward one of associated two of the blades 5 adjacent to each other in the circumferential direction and the reading edge 7 of the other of the associated two blades 5, the forward one of the associated two blades being located forward of the above other blade 5 in the rotation direction RD.
The propeller fan 1 is a so-called boss-less propeller fan that does not include the boss 3. The shaft 4, the blades 5, and the joints 10 are integrally formed of resin. That is, the shaft 4, the blades 5, and the joints 10 form blades united integral with each other.
The trailing edge 9 of each blade 5 has the same configuration as that of any of Embodiments 1 to 4. That is, the first trailing edge 9a is innermost part of the trailing edge 9. The second trailing edge 9b is part of the trailing edge 9 that is adjacent to and outward of the first trailing edge 9a.
The innermost point of the first trailing edge 9a is the first connection point P1. That is, the first connection point P1 is the connection point between the trailing edge 9 of the forward one of associated two blades 5 that are adjacent to each other in the circumferential direction and the leading edge 7 of the other one of the associated two blades 5, the forward one of the associated two blades 5 being located forward of the other of the associated two blades 5 in the rotation direction RD.
In such a manner, in Embodiment 5, the blades 5 are disposed around the shaft 4, and each of the joints 10 is adjacent to the shaft 4 and joins associated two of the blades 5 that are adjacent to each other in the circumferential direction. Because of provision of this configuration, in Embodiment 5, it is possible to obtain the same advantages as in Embodiment 1.
The embodiments of the present invention each relate to a technique of achieving a higher efficiency of a propeller fan and reduction of noise to a lower level in the propeller fan. In the case where an air-sending device is provided with the fan, it can send a larger amount of air with a high efficiency. Furthermore, in the case where an air-conditioning apparatus or a water-heating outdoor unit, which is a refrigeration cycle apparatus including a compressor, a heat exchanger, and other components, is provided with the above fan, it can cause a given amount of air to pass through the heat exchanger with a low noise and a high efficiency, and achieve a lower noise and energy saving at devices. As an example of application of the above cases, Embodiment 6 will be described by referring to the case where the propeller fan 1 according to any of Embodiments 1 to 5 is applied to an outdoor unit of an air-conditioning apparatus, which is an outdoor unit provided with an air-sending device.
As illustrated in
As illustrated in
In the outdoor unit body 51, the propeller fan 1 is provided. The propeller fan 1 is connected to the fan motor 61, which is a drive source and located close to the back surface 51d, with a rotating shaft 62 interposed between the propeller fan 1 and the back surface 51d. The propeller fan 1 is rotated by the fan motor 61.
The inside of the outdoor unit body 51 is partitioned by a partition plate 51g, which is a wall, into a ventilation compartment 56 and a machine compartment 57. In the ventilation compartment 56, the propeller fan 1 is provided, and in the machine compartment 57, the compressor 64 and other components are provided. In the ventilation compartment 56, a heat exchanger 68 is provided close to the side surface 51a and the back surface 51d, and is substantially L-shaped as seen in plan view. The heat exchanger 68 operates as the condenser 72 during the heating operation, and operates as the evaporator 73 during the cooling operation.
A bell mouth 63 is provided outward of the propeller fan 1 provided in the ventilation compartment 56 in the radial direction. The bell mouth 63 is located outward of the outer peripheral edges of the blades 5, and is annular in the rotation direction of the propeller fan 1. The partition plate 51g is located on one of both sides of the bell mouth 63, and part of the heat exchanger 68 is located on the other side of the bell mouth 63.
A front end of the bell mouth 63 is connected to the front panel 52 of the outdoor unit in such a manner as to surround an outer periphery of the air outlet 53. The bell mouth 63 may be formed integral with the front panel 52. Alternatively, the bell mouth 63 and the front panel 52 may be made as separated components and connected to each other. In the bell mouth 63, a flow passage is provided between an air inlet and an air outlet of the bell mouth 63, and serves as a wind passage close to the air outlet 53. That is, the wind passage close to the air outlet 53 is separated from other spaces in the ventilation compartment 56 by the bell mouth 63.
The heat exchanger 68 is located on an air-intake side of the propeller fan 1, and includes a plurality of plate fins that are arranged such that surfaces of the plate fins are parallel to each other, and heat transfer tubes that extend through the fins in the direction in which the plate fins are arranged. In the heat transfer tubes, refrigerant that circulates through the refrigerant circuit flows. In the heat exchanger 68 according to Embodiment 6, the heat transfer tubes are each L-shaped along the side surface 51a and the back surface 51d of the outdoor unit body 51, and extends in a zigzag manner while extending through the fins. The heat exchanger 68 is connected to the compressor 64 by, for example, a pipe 65, and is also connected to, for example, an indoor-side heat exchanger and an expansion valve, not illustrated, thus forming the refrigerant circuit 70 of the air-conditioning apparatus. In the machine compartment 57, a substrate box 66 is provided. In the substrate box 66, a control substrate 67 is provided to control components provided in the outdoor unit.
Also, in Embodiment 6, it is possible to obtain the same advantages or similar advantages to those of Embodiments 1 to 5.
Although Embodiment 6 is described above by referring to by way of example the case where the outdoor unit of the air-conditioning apparatus is applied as the outdoor unit provided with the air-sending device, it is not limited to such a case. For example, the air-sending device can be used as, for example, an outdoor unit of a water heater, and can be widely used as a device that sends air. Also, the air-sending device can be applied to, for example, apparatuses other than outdoor units or facilities.
1 propeller fan, 3 boss, 5 blade, 7 leading edge, 9 trailing edge, 9a first trailing edge, 9b second trailing edge, 11 outer peripheral edge, 13 inner peripheral edge, 31 direction, 33 flow direction of airflow, 51 outdoor unit body, 51a side surface, 51b front surface, 51c side surface, 51d back surface, 51e upper surface, 51f bottom surface, 51g partition plate, 52 front panel, 53 air outlet, 54 fan grille, 56 ventilation compartment, 57 machine compartment, 61 fan motor, 62 rotating shaft, 63 bell mouth, 64 compressor, 65 pipe, 66 substrate box, 67 control substrate, 68 heat exchanger, 70 refrigerant circuit, 72 condenser, 72a condenser fan, 73 evaporator, 73a evaporator fan, 74 expansion valve.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/028957 | 8/9/2017 | WO | 00 |
