JP5014368B2 - Sirocco fan and air conditioner indoor unit using this sirocco fan - Google Patents

Description

  The present invention relates to a sirocco fan that can suppress noise and an indoor unit of an air conditioner using the sirocco fan.

  A sirocco fan used in an indoor unit of an air conditioner has a fan boss and a rib surrounding the fan boss attached to the center of the main plate of the rotor blade. The rib has been set so small that its outer diameter is less than 0.2 times the fan diameter so as not to become resistance to wind flow (see, for example, Patent Document 1).

JP 2007-205841 A (FIG. 4)

  By the way, the sirocco fan flows in the centrifugal direction with the wind direction perpendicular to the axis. For this reason, in the case where the rib surrounding the fan boss is set to have a relatively small diameter (outer diameter is less than 0.2 times the fan diameter) as in the conventional sirocco fan, the main plate The flow was concentrated between nearby wings, and this was one of the sources of noise.

  Further, as the rib diameter is reduced, the fan boss diameter is also reduced, and the weight of the fan center is reduced. For this reason, fan vibration is likely to occur, which has been one of the sources of noise.

  The technical problem of the present invention is to be able to suppress an increase in noise at a predetermined air volume and an increase in noise due to fan vibration.

The sirocco fan according to the present invention is provided with a cylindrical first rib around a fan boss formed at the center of the main plate of the rotor blade, and a cylindrical second through a flange around the first rib. The outer diameter of the second rib is 0.2 to 0.61 times the fan diameter .

According to the sirocco fan of the present invention, the diameter of the rib portion is increased by providing the cylindrical second rib around the cylindrical first rib via the flange and making the rib double. Therefore, the outer second rib can be an obstacle to the wind flowing near the main plate, and the flow can be prevented from being concentrated between the wings near the main plate. For this reason, the noise at the time of predetermined air volume can be made small. At that time, by setting the outer diameter of the second rib to be 0.2 to 0.61 times the fan diameter, the second rib does not become a great resistance to the flow in the vicinity of the main plate, and the noise increasing action is achieved. It is possible to suppress the influence from expanding. For this reason, the noise reduction effect by reduction of the airflow between blades near the main plate can be stably obtained.
Further, it is possible to suppress the occurrence of fan shake due to an increase in the weight of the fan center. For this reason, an increase in noise due to fan vibration can also be suppressed.

It is the front view and side sectional drawing which show the structure of the main board of the rotary blade of the sirocco fan which concerns on Embodiment 1 of this invention. It is a perspective view which shows roughly the relationship between the rotary blade of the double suction type sirocco fan which concerns on Embodiment 1 of this invention, and the double suction type scroll casing which accommodates this and forms an air path. It is a graph which shows the PQ characteristic of the sirocco fan which concerns on Embodiment 1 of this invention. It is sectional drawing which looked at the rotary blade and scroll casing of the sirocco fan which concern on Embodiment 1 of this invention from the side. It is a graph which shows the blade | wing air volume distribution of the sirocco fan which concerns on Embodiment 1 of this invention. It is a graph which shows the relationship between the outer diameter of the 2nd rib with respect to the fan diameter of the sirocco fan which concerns on Embodiment 1 of this invention, and noise. It is a graph which shows the relationship between the width | variety of the axial direction of a 2nd rib with respect to the fan diameter of the sirocco fan which concerns on Embodiment 1 of this invention, and noise. It is the front view and side sectional drawing which show the structure of the main board of the rotary blade of the sirocco fan which concerns on Embodiment 2 of this invention.

Embodiment 1. FIG.
The present invention will be described below with reference to illustrated embodiments.
1A and 1B are a front view and a side sectional view showing a configuration of a main plate of a rotary blade of a double suction type sirocco fan according to Embodiment 1 of the present invention. FIG. 2 is a perspective view schematically showing the relationship between the rotor blades of the sirocco fan according to the present embodiment and a double suction type scroll casing that accommodates the rotor blades and forms an air passage.

  1 and 2, a rotary blade 8 is accommodated in a scroll casing 9 of a sirocco fan 10, and a main plate 1 is disposed at an intermediate portion in the extending direction of the rotary blade 8. A fan boss 2 connected to a motor shaft of a fan motor (not shown) by a screw or the like is provided at the center of the main plate 1, and a first rib 3 is provided around the fan boss 2. A second rib 4 is provided around via an inward flange 4a. A plurality of blades 5 extending in the axial direction are attached to the outer edge portions of both end faces of the main plate 1 at equal intervals, and the extending ends of these blades 5 are attached to the rings 11a and 11b. .

  Next, the operation of the sirocco fan of this embodiment will be described. As described above, the fan boss 2 and the motor shaft are connected by screws or the like, and the rotating blades 8 of the sirocco fan 10 are rotated by the rotation of the fan motor.

  FIG. 3 is a graph showing the PQ characteristics of the sirocco fan 10 when the second rib 4 is attached, where P is the static pressure and Q is the air volume. The rotor blade 8 of the sirocco fan 10 is a double suction type. The diameter of the rotor blade 8, that is, the fan diameter (FIG. 4) is φ192 mm, the fan width is 300 mm, the scroll casing 9 height (FIG. 4) is 240 mm, and the number of blades is Forty sheets, the outer diameter of the first rib 3 is 37 mm, and the width of the first rib 3 is 9 mm on one side.

  The PQ characteristic represents the relationship between the static pressure P, which is the ventilation resistance, and the air volume Q, with the fan speed being constant. The smaller the draft resistance, the easier the wind will flow, and the greater the draft resistance, the more difficult the wind will flow. Therefore, the smaller the static pressure, the larger the air volume, and the larger the static pressure, the smaller the air volume. However, there is a region where the static pressure is reduced even when the air volume is reduced, and this region is called a surging region. In the surging region, the flow is likely to be unstable, which may cause abnormal sounds. Hereinafter, the high static pressure and low air volume side is referred to as a cutoff side (upper left side of the graph), and the low static pressure and high air volume side is referred to as an open side (lower right side of the graph).

  The noise values with and without the second rib 4 at the operating points A and B on the PQ characteristic graph of FIG. The operating point A is located on the closing side, and the point B is located on the open side.

  As can be seen from Table 1, the noise values at both the operating points A and B are smaller when the second rib 4 is present, and the operating point A at the shut-off side is the noise due to the second rib 4. The reduction effect is great.

Next, the reason will be described.
FIG. 4 is a cross-sectional view of the rotary blade 8 and the scroll casing 9 of the sirocco fan 10 as seen from the side. FIG. 5 is a graph showing the relationship between the airflows between the blades at the operating point A (vertical axis) and the blade positions (horizontal axis). The vertical axis in FIG. 5 is positive (+) when flowing from the inside to the outside of the fan between the blades, and negative (−) when flowing from the outside to the inside. The position of 4 wings is expressed with the short hand of the watch.

As shown in FIG. 5, the maximum airflow between the blades is approximately 10:30 with or without the second rib 4, but the maximum value is smaller when the second rib 4 is present. Assuming that the air flow between the blades is Qi (i = 1 to 40 since the number of blades is 40), the following equation (1) is generally established for the noise SPL.
SPL∝Σ {10log ₁₀ (Qi) ⁶ } (1)

  From equation (1), the noise value becomes minimum when the inter-blade air volume Qi is all equal, and the noise value increases as the maximum value of the inter-blade air volume Qi increases. Therefore, when the second rib 4 is present, the maximum value of the inter-blade air volume Qi is smaller than when the second rib 4 is not present, so that the noise value is small.

  Further, the operating point A has a greater noise reduction effect due to the second rib 4 than the operating point B. Although this has the effect of reducing the maximum value of the inter-blade airflow rate Qi by the second rib 4 also at the operating point B, since the operating point B is an open side operating point, the speed near the main plate 1 is the operating point A. This is because the second rib 4 becomes an obstacle to the flow in the vicinity of the main plate 1 and causes an increase in noise.

  FIG. 6 is a graph showing the relationship between the noise difference due to the presence or absence of the second rib 4 and the outer diameter / fan diameter of the second rib 4. Here, the noise difference is obtained by subtracting the noise value with the second rib 4 from the noise value without the second rib 4, and the width of the first and second ribs 3 and 4 in the rotation axis direction is One side is 10 mm.

  As apparent from FIG. 6, the noise is smaller with the second rib 4 when the outer diameter / fan diameter of the second rib 4 is in the range of 0.2 to 0.61 times. This is because the second rib 4 becomes a resistance against the flow in the vicinity of the main plate 1 and has an effect of reducing the air flow between the blades in the vicinity of the main plate 1. For this reason, when the outer diameter / fan diameter of the second rib 4 is in the range of 0.2 to 0.61 times, the noise between the blades in the vicinity of the main plate 1 is reduced, so that the noise is reduced. When the outer diameter / fan diameter of the second rib 4 is larger than 0.61 times, the second rib 4 has a greater resistance to the flow in the vicinity of the main plate 1 than the noise reduction effect due to the reduction of the airflow between the blades in the vicinity of the main plate 1. As a result, the noise increasing action becomes dominant and the noise increases.

  FIG. 7 is a graph showing the relationship between the noise difference due to the presence or absence of the second rib 4 and the width / fan diameter (in the direction of the rotation axis) of the second rib 4. Here again, the noise difference is obtained by subtracting the noise value with the second rib 4 from the noise value without the second rib 4, and the width of the second rib 4 in the rotation axis direction is the second rib. 4, and the outer diameter of the second rib 4 is φ117.12 mm.

  As is clear from FIG. 7, when the width / fan diameter of the second rib 4 is 0.26 times or less, the noise is smaller with the second rib 4. This is because the second rib 4 becomes a resistance against the flow in the vicinity of the main plate 1 and has an effect of reducing the air flow between the blades in the vicinity of the main plate 1. For this reason, when the width / fan diameter of the second rib 4 is 0.26 times or less, the noise is reduced because the airflow between the blades near the main plate 1 is reduced. When the width / fan diameter of the second rib 4 is larger than 0.26 times, the second rib 4 has a greater resistance to the flow in the vicinity of the main plate 1 than the noise reduction effect due to the reduction in the airflow between the blades in the vicinity of the main plate 1. As a result, the noise increasing action becomes dominant and the noise increases.

As described above, in the sirocco fan of the present embodiment, the first rib 3 is provided around the fan boss 2 formed at the center of the main plate 1, and the second rib 4 is provided around the first rib 3. Since it is provided, the outer second rib can be an obstacle to the wind flowing near the main plate 1, and the flow can be prevented from concentrating between the blades near the main plate 1. For this reason, the noise at the time of predetermined air volume can be made small.
Further, the second rib 4 increases the weight of the fan center, and can suppress the occurrence of fan shake. For this reason, an increase in noise due to fan vibration can also be suppressed.

  In addition, since the outer diameter of the second rib 4 is set to fall within the range of 0.2 to 0.61 times the fan diameter, the second rib 4 has a great resistance to the flow in the vicinity of the main plate 1. Therefore, it is possible to suppress the influence of the noise increasing action from expanding. For this reason, the noise reduction effect by reduction of the airflow between the blades near the main plate 1 can be stably obtained.

  Further, since the axial width of the second rib 4 is set to 0.26 times or less of the fan diameter, the second rib 4 does not become a great resistance to the flow in the vicinity of the main plate 1, and the influence of the noise increasing effect is exerted. Can be prevented from expanding. For this reason, the noise reduction effect by reduction of the airflow between the blades near the main plate 1 can be stably obtained.

  Moreover, by using such a sirocco fan for an indoor unit of an air conditioner, an indoor unit with low noise and low vibration can be obtained.

Embodiment 2. FIG.
FIG. 8 is a front view and a side cross-sectional view showing the configuration of the main plate of the rotor blade of the double suction type sirocco fan according to Embodiment 2 of the present invention. In FIG. Is attached. Here, in the description, reference is made to FIG. 2 described above.

  The sirocco fan according to the present embodiment is configured such that the inward flange 4a and the first rib 3 of the second rib 4 of the first embodiment are deleted, and the material of the fan boss 2A is made of aluminum, and its outer shape Is enlarged so as to be substantially equal to the inner diameter of the second rib (hereinafter simply referred to as “rib”) 4.

  More specifically, the rib 4 is set to have an outer shape of 0.2 to 0.61 times the fan diameter and an axial width of 0.26 times or less of the fan diameter.

  On the other hand, the sirocco fan has a fan diameter of 192 mm, a fan width of 300 mm, a scroll casing height of 240 mm, a blade count of 40, and is made of polypropylene.

  That is, in the sirocco fan of the present embodiment, the fan boss 2A is made of a material having a density larger than the density of the fan. The noise value of the sirocco fan of this embodiment (FIG. 8) and the noise value of the sirocco fan of FIG. In Table 2 below, the operating point A is located on the closing side and the operating point B is located on the open side.

  As is apparent from Table 2, the noise value of the sirocco fan of FIG. 8 is smaller than that of the sirocco fan of FIG. This is due to the fact that the center of gravity of the rotor blade 8 of the sirocco fan 10 is stabilized and the fan is difficult to shake during rotation because the weight inside the rib 4 is larger in the case of FIG.

  The operating point B (open side) has a greater noise reduction effect than the operating point A (closing side), but this is because the operating point B with a large air volume has a larger fan shake in the sirocco fan of FIG. Because.

  Next, in order to evaluate the breaking strength of the fan, the fan shown in FIGS. 1 and 8 is rotated in the absence of the scroll casing 9, and the result of obtaining the minimum number of revolutions that the fan breaks is shown in Table 3 below.

  As is apparent from Table 3, the minimum number of revolutions of the fan of FIG. 8 is larger and the breaking strength of the fan is improved. This is because the center of gravity of the rotor blade 8 of the sirocco fan 10 is stabilized because the weight inside the rib 4 is larger in FIG. 8, and the fan is difficult to shake during rotation.

  Next, a case where the material of the fan boss 2A and the material of the rotor blades 8 of the sirocco fan 10 are changed will be described. Generally, the material of the fan boss is aluminum, and the material of the sirocco fan is a plastic resin such as polypropylene, or a steel plate made mainly of iron. The relationship between these materials and density is shown in Table 4 below.

  In the state of FIG. 8, only the material of the fan boss 2 </ b> A is changed from aluminum to copper, the fan is rotated without the scroll casing 9, and the result of obtaining the minimum number of rotations that the fan breaks is shown in Table 5 below. However, the material of the rotor blade 8 of the sirocco fan 10 is polypropylene.

  As is apparent from Table 5, the minimum rotation speed at which the fan breaks is greater when the material of the fan boss 2A is copper, and the breaking strength of the fan is improved. This is because the weight inside the rib 4 is larger for copper, so that the center of gravity of the rotor blade 8 of the sirocco fan 10 is stabilized and the fan is less likely to shake during rotation.

  Next, in the state of FIG. 8, the material of the rotor blades 8 of the sirocco fan 10 is iron, the material of the fan boss 2A is changed from aluminum to copper, the fan is rotated without the scroll casing 9, and the fan is destroyed. Table 6 below shows the results obtained for the number of rotations.

  As is apparent from Table 6, the minimum rotation speed at which the fan breaks is larger when the material of the fan boss 2A is copper, and the breaking strength of the fan is improved. This is because the weight inside the rib 4 is larger for copper, so that the center of gravity of the rotor blade 8 of the sirocco fan 10 is stabilized and the fan is less likely to shake during rotation.

  From Tables 5 and 6, it can be seen that the higher the density of the material of the fan boss 2A, the larger the minimum number of revolutions that the fan can break. Further, it can be seen that if the density of the material of the fan boss 2A is larger than the density of the material of the rotor blade 8 of the sirocco fan 10, the minimum number of revolutions at which the fan breaks can be reliably increased.

  Further, since the outer diameter of the rib 4 is set so as to be within the range of 0.2 to 0.61 times the fan diameter, the rib 4 does not become a great resistance to the flow in the vicinity of the main plate 1 and the noise increasing action is achieved. It is possible to suppress the influence from expanding. For this reason, the noise reduction effect by reduction of the airflow between the blades near the main plate 1 can be stably obtained.

  Further, since the axial width of the rib 4 is 0.26 times or less of the fan diameter, the rib 4 does not become a great resistance to the flow in the vicinity of the main plate 1, and the influence of the noise increasing action is prevented from expanding. can do. For this reason, the noise reduction effect by reduction of the airflow between the blades near the main plate 1 can be stably obtained.

  Moreover, by using such a sirocco fan for an indoor unit of an air conditioner, an indoor unit with low noise and low vibration can be obtained.

  As described above, according to the sirocco fan of the present embodiment, the rib 4 having the outer diameter of 0.2 to 0.61 times the fan diameter is provided around the fan boss 2A, and the outer diameter of the fan boss 2A is set to the rib 4. Therefore, the noise value can be reduced and the breaking strength can be improved. In addition to this, the breaking strength can be further improved by making the material density of the fan boss 2A larger than the material density of the sirocco fan.

  DESCRIPTION OF SYMBOLS 1 Main board, 2, 2A fan boss, 3 1st rib, 4 2nd rib (rib), 5 blade | wing, 8 rotary blade, 9 scroll casing, 10 sirocco fan.

Claims (3)

A cylindrical first rib is provided around a fan boss formed at the center of the main plate of the rotor blade, and a cylindrical second rib is provided around the first rib via a flange . A sirocco fan characterized in that the outer diameter of the rib 2 is 0.2 to 0.61 times the fan diameter . Sirocco fan according to claim 1, characterized in that the axial width of the second rib and less 0.26 times the fan diameter. An indoor unit of an air conditioner using the sirocco fan according to claim 1 or 2 .

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