JP2007255426A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power-saved and silent room air conditioner by reducing noise while increasing the air volume of a once-through fan in the indoor unit of the air conditioner. <P>SOLUTION: In the once-through fan 1, a disk 13 has vanes 12. A camber line 17 indicating the center of the cross sectional thickness of the vane includes two circular arcs. The warped direction of each circular arc is inverted. The pressure surface 18 of the vane 12 matches the rotating axis direction. The width of a flow passage between the vanes can be obtained since their outer diameter sides vary within the range of 60 to 80% relative to the inner diameter sides. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cross-flow fan provided in an indoor unit of an air conditioner.

  In recent years, air conditioners have been required to save power and noise. As a method for reducing power consumption, indoor air is installed in indoor units and heat-exchanged with refrigerant flowing in the heat exchanger. There is a method of increasing the air volume of the fan that blows the air out of the indoor unit. As a fan for an indoor unit, in the case of a wall-mounted air conditioner, a cross-flow fan (cross flow fan) is mainly used. As is well known, increasing the air volume of the fan of the indoor unit improves the heat exchange performance of the indoor heat exchanger. If the fan air volume can be increased without increasing the fan speed, the overall performance of the air conditioner can be improved, and the same air conditioning effect can be produced with less power consumption (without changing power consumption). .

  As a method for increasing the air volume of the blower of the indoor unit, as described above, it is conceivable to increase the rotational speed of the cross-flow fan that is the blower of the indoor unit and to increase the outer diameter of the fan.

  By the way, the turbulent sound during operation of the indoor unit (sound distributed in the high frequency band) is proportional to the seventh to eighth power of the cross-flow fan rotation speed. Therefore, when the air volume is increased by 30% by the former method, 9 dB Will also increase. On the other hand, since the turbulent sound is proportional to the fourth to fifth power of the outer diameter of the cross-flow fan, when the air volume is increased by 30% by the latter method, the increase can be limited to 5 dB.

  As a result, the latter method is considered appropriate for increasing the air volume without increasing the noise (turbulent flow sound) as much as possible. However, the size of the indoor unit is limited, and therefore the size of the cross-flow fan provided inside the indoor unit is also limited, and it is difficult to increase the outer diameter from the current state. Further, when the outer diameter of the cross-flow fan is increased to the limit, the gap Z between the cross-flow fan and the nose is reduced, and the abnormal noise (frequency Z · generated by the product of the number of blades Z and the rotational speed N (/ sec)) is increased. N (Hz) or its higher frequency) and the distance between the indoor heat exchanger and the once-through fan, the vanes of the once-through fan are in the wake region (the velocity distribution of the airflow passing through the heat exchanger is downstream of the pipe However, there is a problem of sound generated when the blade approaches the region where the velocity distribution is greatly changed locally and the blades pass through the region.

  Therefore, Patent Document 1 and Patent Document 2 are known as conventional techniques for reducing noise by suppressing blade noise caused by interference with the cross-flow fan. These two documents are the same in principle even though the effects are different, and have the effect of suppressing noise (blade sound) even if the cross-flow fan is enlarged to increase the air volume and the nose gap is reduced.

  That is, in principle, by changing the blade outer diameter of the cross-flow fan with respect to the rotation axis direction, the blade outer peripheral tip structure of the cross-flow fan is inclined with respect to the nose, and the blade outer peripheral tip is nose (or , The time difference (phase difference) is generated when passing through the wake region.

  Therefore, the periodic noise generated from the positional relationship between the blade outer peripheral tip and the nose is temporally dispersed to suppress the blade noise, and the nose gap is reduced to increase the air volume.

  As other conventional techniques, Patent Documents 3 and 4 are known. The contents described in these publications will be described. In order to prevent the blade noise of the once-through fan, the pitch of the blades in the circumferential direction is made unequal and the circumferential phase of each blade is varied to suppress the peak sound and reduce the overall noise. It is.

  Although the techniques for reducing noise and increasing air volume described in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4 are different, they are common in that they disperse the blade sound periodically. In addition, it is possible to increase the amount of airflow with reduced noise (blade sound) and improve the performance of the air conditioner.

Japanese Patent Application Laid-Open No. 9-100795 JP 2001-50189 A Japanese Patent Laid-Open No. 6-129387 JP-A-6-173886

  However, at present, the air conditioner is required to have further power saving and noise reduction (low noise and high air volume), and for this purpose, a high efficiency and low noise cross-flow fan is required. Further, the sound of the cross-flow fan includes a broadband turbulent sound generated by a fluid. Even if the above-described conventional technology can suppress periodic blade noise, the turbulent sound cannot be reduced. For this reason, it is difficult to realize further low noise and power saving only by the technique found in the prior art.

  An object of the present invention is to provide a room air conditioner that reduces noise while reducing turbulent noise caused by fluid and realizes power saving by increasing air volume.

  In the air conditioner having a cross-flow fan in the indoor unit, the warp line indicating the thickness center of the blade cross section of the cross-flow fan includes two arcs, and the warp directions of the respective arcs are reversed to each other. Is achieved.

  Moreover, the said objective is achieved by making the pressure surface of the blade | wing which comprises the said cross-flow fan correspond with a rotating shaft direction in the air conditioner provided with the cross-flow fan in the indoor unit.

  Further, the object is to provide an air conditioner having a cross-flow fan in the indoor unit, so that the flow path width between the blades of the cross-flow fan is in a range of 60 to 80% on the outer diameter side with respect to the inner diameter side. This is achieved by setting the thickness of.

  The second means is that, in an air conditioner including a cross-flow fan as a blower of the indoor unit, the structure is such that the pressure surfaces of the blades constituting the fan are aligned with the rotation axis direction. By matching the pressure surfaces, the velocity distribution in the direction of the rotation axis is balanced without being disturbed, leading to improved performance of the cross-flow fan.

  The third means is that in the air conditioner having a cross-flow fan as a blower of the indoor unit, the fan passage width between the blades is changed to 60 to 80% on the outer diameter side with respect to the inner diameter side. It is. The cross-flow fan is basically a speed increasing blade row in which the fluid speed increases toward the blow-out side, and the degree of fluid acceleration is determined by the width of the flow path between the blades. Can be greatly affected.

  The fourth means is a structure in which the fan blade outer diameter is changed with respect to the rotation axis direction in addition to any of the above three means in order to enhance the low noise effect. By changing the outer diameter of the blade, a time difference (phase difference) is given to the interference of the blade, thereby suppressing the blade noise and reducing the noise.

  According to the present invention, it is possible to provide a low-power and quiet air conditioner by reducing the noise while increasing the air volume by reducing the efficiency and noise of the once-through fan.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 shows the entire room air conditioner indoor unit, where (a) shows an overall view from the front, and (b) shows a cross section from the side of the indoor unit. The entire unit is covered with a decorative frame 2 and includes a filter 5, a heat exchanger 6, and a cross-flow fan 1 in this order. A casing 7 is provided below the cross-flow fan 1.

  An overview of the once-through fan 1 is shown in FIG. 2, (c) shows the overall shape, and (d) shows a cross section viewed from the direction of the rotation axis. A circular plate 13 in which the blades 12 are arranged in the circumferential direction is used as one fan block, and one cross-flow fan 1 is configured by combining several fan blocks in the rotation axis direction. A boss-attached end face disk 15 having an end face disk 14 and a boss 16 is attached to both ends of the fan, and the end face disk 14 is rotated on the bearing side and the boss end face disk 15 is rotated on the motor shaft side. .

  In the actual operation state of the unit, the cross-flow fan 1 is rotated clockwise in FIG. 1B by the motor 10 and sucks air from the front grill 3 and the upper grill 4 provided in the decorative frame 2, The air is blown from the outlet. The airflow inside the unit reaches the heat exchanger 6 through the filter 5, and is cooled or warmed in the process of passing through the heat exchanger 6. The heat-exchanged air current passes through the once-through fan 1 and exits toward the casing 7, and flows out with the wind direction controlled by the vertical wind direction plate 8 and the horizontal wind direction plate 9 in the vicinity of the outlet.

  3, 4, and 5 show the characteristics of the cross-flow fan according to the present embodiment, and are enlarged views of a cross section of the cross-flow fan 1 as viewed from the rotation axis direction. The contents are described below.

3, and the camber line 17 indicating the center of the thickness of the blade 12 is formed from a second circular arc of curvature radius [rho ₁ and [rho _2, inverts the respective arc warp directions. In addition, the distribution of the thickness forming the blade 12 forms a blade shape that gradually becomes thinner from the middle of the chord length toward both ends of the blade outer peripheral tip and the blade inner peripheral tip.

  Here, focusing on the properties of the fluid, generally, the turbulent sound increases as the flow velocity increases, and the required input also increases. The turbulent flow noise depends on the flow velocity (representative velocity) V (m / s) passing through the blade tip of the once-through fan, as shown in the following formula (1).

  α is a conversion coefficient and takes a constant value that varies depending on the type and state of the fluid machine. Therefore, the noise value SPL varies greatly depending on the representative speed V. In the once-through fan used in the room air conditioner, the noise value SPL can be reduced by 3 dB if the representative speed V is reduced by 10%. The input also depends on the flow velocity (representative speed) V blown out through the blades of the cross-flow fan, as shown in the following formula (2).

w is an input (w / m ³ ) given to the fluid per unit volume, and p and ρ represent pressure (Pa) and density (kg / m ³ ) in the fluid region. In a state where the room air conditioner is operated in the atmosphere, the pressure p can be considered to have almost no influence by being approximated to the atmospheric pressure on both the upstream side and the downstream side. Further, in the air flow performance of the cross-flow fan of the room air conditioner, the fluid can be regarded as incompressible, so the density ρ is constant. It becomes. Therefore, when the flow rate is quantitative, the input w can be reduced by reducing the flow velocity V by sending out the fluid using a wide area. When the input w is constant, a larger flow rate can be flowed by sending out the fluid in a wide area.

  From the above, if the center line 17 of the cross-sectional shape of the cross section of the cross-flow fan 1 is reversed by two arcs, the outflow region in the vicinity of the outer periphery of the blade on the casing 7 side, which becomes the maximum flow velocity region, is expanded, and the fluid is slowly and slowly sent out. be able to. A difference from a blade formed with one circular arc (for example, formed with only ρ2 in FIG. 3) will be described. The flow analysis of the cross-flow fan using the blades formed by one arc was performed, and the flow velocity distribution between the outermost blades (from the tip of the adjacent blade in front of the rotation direction to the tip of the blade to be calculated) was obtained. According to this, it was found that the flow velocity distribution was not uniform, and the flow velocity near the tip of the blade to be calculated protruded and was fast. As described above, the flow velocity is directly related to noise, and only a part of the flow velocity is high, so it has been found that it does not contribute much to the total air volume. Therefore, in this embodiment, it has been found that the protruding high flow velocity can be suppressed by curving the outer peripheral side tip of the blade in the half rotation direction.

As a result, low noise and high efficiency are achieved, and the performance of the air conditioner is improved by saving power and increasing the air volume. The effect about the ventilation performance is shown below. FIG. 6 shows the relationship between the radius of curvature ρ ₁ and the efficiency η when the cross-flow fan 1 is clockwise (clockwise) in FIG. 2D, and the horizontal axis indicates the warping direction of the radius of curvature ρ _2. The reciprocal of the radius of curvature ρ ₁ when positive is taken, and the efficiency ratio η / η ₀ is taken on the vertical axis. (Η ₀ indicates the efficiency of the conventional once-through fan, and the conventional fan will be described with reference to FIG. 8.) The efficiency η used as an index for performance evaluation is the fan efficiency of the once-through fan, as shown in Equation (3). expressed.

Where P _T is the total pressure (Pa), Q is the flow rate (m ³ / s), T is the torque of the cross-flow fan (N · m), ω is the angular velocity (rad / s) of the cross-flow fan, The total pressure P _T is further developed as shown in Equation (4).

The total pressure P _T is represented by the sum of the static pressure P _s and the dynamic pressure P _d , and the dynamic pressure P _d is determined by the density ρ and the representative speed V. From the above, the efficiency η can be arranged in the form shown in Equation (5).

When conditions of constant flow rate Q and constant rotation speed (constant angular velocity ω) are given, the efficiency η depends on the static pressure change ΔP _s from the upstream side to the downstream side of the cross-flow fan, the representative speed change ΔV ² , and the torque T of the cross-flow fan. Will be decided. In the performance evaluation in FIG. 6, the flow rate and the number of rotations are constant, and the pressure surface is the same in each blade shape, the maximum wall thickness value is fixed, and both the blade outer diameter and the minimum inner diameter are fixed. Therefore, the inner / outer diameter ratio = constant condition is given. The change state of the blade outer peripheral direction of the rotation axis takes the form shown in FIG. 4 (f) which varies linearly, given the conditions that a D ₁ <D _2, from D ₁ in all conditions to D ₂ The rate of change is the same. Therefore, from FIG. 6, the air blowing performance can be evaluated using the curvature radius as a parameter, and the maximum efficiency point is in the negative region where the curvature radii of the two arcs forming the center line 17 of the blade cross-sectional shape are reversed from each other. I understand that. In other words, the shape in which the outer peripheral tip of the blade 12 is warped has the effect of improving the performance of the cross-flow fan 1, which leads to the improvement of the performance of the air conditioner.

In FIG. 4 (e), the two cross sections of the blades 12 are cross sections at arbitrary positions with respect to the rotation axis direction, and the positions are cross sections obtained by viewing one fan block from the radial direction. This is shown in FIG. A thick and large cross section A represents the disk 3 side of one fan block, and a thin and small cross section A ′ represents the opposite side. From this sectional view, it can be seen that the pressure surface 18 substantially coincides with the rotation axis direction. Further, in (f), the change in the outer diameter with respect to the rotation axis direction linearly changes from the diameter D ₁ to the diameter D ₂ , and the relationship is D ₁ ≠ D ₂ as described in the prior art. This is to add an effect of reducing the noise of the blades. In general, a pressure surface in a blade of a blower is an area that directly gives power to a fluid and greatly affects the blowing performance. If the pressure surface is in a distorted state, the fluid balance is deteriorated and the non-uniform flow becomes strong, resulting in problems such as performance degradation and noise increase. This problem arises from the fluid properties described above, and can be solved basically by the same principle. The contents will be described below. As can be seen from the mathematical expressions (1) and (2) described above, the noise value and input are greatly affected by the representative speed V. Therefore, as the flow velocity V increases, the noise increases and the input also increases. Here, attention is paid to the velocity distribution in the rotation axis direction of the fluid flowing out between the blades. When the pressure surface is in a distorted state with respect to the rotation axis direction, the velocity distribution greatly changes with respect to the rotation axis direction due to the shape. On the other hand, when the pressure surfaces coincide with the rotation axis direction, the velocity distribution is almost uniform and the fluid flows out at a uniform flow velocity. At this time, the flow rate is constant, both speed distributions are compared, and the influence on the performance will be described below. A blade with a distorted pressure surface has a region where the flow velocity V is locally fast and slow with respect to the average flow velocity V _aVe calculated from the flow rate. In, it becomes large, and it becomes small in the region where the speed is low. And since the input increases with the square of the flow velocity as shown in Equation (2), this speed distribution has more input increase in the high speed region than input decrease in the low speed region, and as a result, The total input is larger than the input of uniform velocity distribution as a whole. That is, the blades having the same pressure surface generally have substantially the same flow velocity (V _aVe ) with respect to the average flow velocity V _aVe calculated from the flow rate, and it can be said that the velocity distribution has the least input. Further, considering the noise aspect, as shown in the equation (1), the blade with the distorted pressure surface has a high speed because the region where the flow velocity V is fast, and the blade with the matching pressure surface has the highest noise. The velocity distribution becomes low. From the viewpoint of velocity distribution, the blades whose pressure surfaces coincide with each other in the direction of the rotation axis have the best velocity and uniform input and noise. Therefore, by aligning the pressure surface 18 in the direction of the rotation axis as described above, the balance of the fluid is improved, and improvement of air blowing performance and silence can be realized.

It is possible to improve the performance by defining the flow path width of the blades, the contents of which will be described with reference to FIG. The inter-blade channel width B shown in (g) is the maximum width B _max on the blade inner diameter side and the minimum width B _miN on the blade outer diameter side. The maximum width B _max is expressed as B _max = r _iN siNθ by the blade inner diameter r _iN shown in (h) and the blade interval θ determined from the blade inner diameter tip / rotation axis as a base point, and the minimum width B _miN is on the blade outer diameter side. It is defined as the minimum width. FIG. 7 shows the result of evaluating the fan performance using only the flow path width change rate B _miN / B _max as a parameter in this state. Also, the blade maximum wall thickness is fixed and the inner and outer diameters of the blade are fixed, giving the condition that the inner / outer diameter ratio is constant. Both ends of the inner and outer diameters of the blade are the same shape (same R) in both conditions Comparing. The efficiency η is the fan efficiency η of the once-through fan shown in terms of the air blowing performance, and the definition is the same as described above. It depends on the number. Here, the relationship between the efficiency η and the flow path width change rate B _miN / B _max will be described. In the vicinity of the outlet of the _once- through fan, the flow rate Q is constant, so that the fluid velocity passing through the channel width B _miN increases as B _miN / B _max decreases.

However, due to the nature of the fluid, the greater the fluid velocity, the greater the loss in each fluid region, so the flow velocity falls to a velocity distribution corresponding to the flow rate Q on the downstream side of the cross-flow fan. Therefore, the fluid excessively is accelerated torque T applied by the cross-flow fan, thus increasing energy lost as loss without increasing the static pressure P _s. As a result, in the region where the flow path width change ratio B _miN / B _max is 55% or less, the flow path width B _miN is narrowed, resulting in poor efficiency. On the other _{hand, in the} region where B _miN / B _max is large, the fluid velocity passing through the flow path width B _miN is small as _opposed to the small case. Therefore, the fluid flows out without being sufficiently accelerated at the once-through fan outlet. In this state, even if the torque T is applied to the once-through fan, neither the static pressure P _s nor the dynamic pressure P _d rises, and the fluid passes through the once-through fan. As a result, the efficiency ratio η / η _max shows a low value in the region where the flow path width change rate B _miN / B _max is 85% or more, and the efficiency is deteriorated. Then, in the flow path width variation rate B _MIN / B _max 60 to 80% of the area, the static pressure P _s, the dynamic pressure P _d, since a good balance of torque T, the efficiency ratio eta / eta _max a high value Show. From the above, it can be seen that the efficiency is high and the fan performance is improved in the region where the fan blade flow path width is 60 to 80% on the outer diameter side with respect to the inner diameter side. When the indoor unit is operated with the cross-flow fan having the structure range described above, the air volume can be increased with the same power consumption, which leads to improvement of the performance of the entire air conditioner.

The above description has been made with the cross-flow fan in which the blade-to-blade intervals are formed at equal intervals. This will be described below. Currently, there are many cross-flow fans built in indoor units of air conditioners in which blades are arranged at unequal intervals in the circumferential direction. That is, B _miN and B _max between the blades of the cross-flow fan are unequal, and the widths of the channels are not equal. This is due to the application of the above-mentioned conventional technology, which has the effect of reducing the noise of the blades caused by interference when the once-through fan is rotating by shifting the phase of the blades. It is widely used in indoor units. For this reason, the flow passage width change rate B _miN / B _max described above has a different value between the blades in the cross-flow fan with blades having unequal intervals. Therefore, an averaged value is used to uniquely determine the flow path width change rate B _miN / B _max for the _cross- flow fans having unequal blade intervals. When N blades are arranged at unequal intervals in the circumferential direction of one cross-flow fan block, B _max = r _iN siN (2π / N) and B _miN = (ΣB ′ _miN ) / N. B _max is calculated from the angle obtained by averaging one round of the once-through fan by the number N of blades, and B _miN is the sum (ΣB ′) between all the blades when the minimum flow path width between each blade of the _once- through fan is B ′ _{miN. miN} ) is obtained by averaging the number N of blades. By doing so, it becomes possible to uniquely determine the flow path width change rate B _miN / B _max in _cross- flow fans with unequal intervals.

The adjustment of the channel width can be basically handled by adjusting the thickness of the blade. Even if the blades are equally spaced, if the flow path width change rate B _miN / B _max is 60 to 80%, the thickness of any blade (one or more blades) is set to the other blades. It may be different from the thickness (all the blades may not be the same thickness), and even if they are unequal, if the previous average value is within that value, the thickness of all the blades is the same Not necessarily.

FIG. 8 shows a performance comparison between the conventional fan and this embodiment fan. The horizontal axis of the air volume ratio Q / Q _0, all the pressure ratio on the vertical axis, respectively PT / PT _0, input ratio Lm / Lm _0, taking the noise value SL-SL _0. Here, Q ₀ , PT ₀ , Lm ₀ , and SL ₀ represent conventional reference values. The conditions are the same, and the conventional fan has the same inner and outer diameter as the fan of the present embodiment, and therefore the inner and outer diameter ratios are also equal. Further, the outer diameter of the blade changes with respect to the rotational axis direction, and linearly changes so as to have the maximum outer diameter in the vicinity of an intermediate position in the axial direction of one fan block. This has the effect of suppressing the blade noise also used in this embodiment, but the other blade flow path width change is 60 to 80%, the two arcs are reversed, and the pressure surfaces are made to coincide. It is not in the shape. Therefore, as shown in FIG. 8, the total pressure ratio is about + 20%, the input ratio is about -10%, and the noise value is about -1 dB when compared with each air volume ratio. There is a noticeable improvement in

1 is an overall view showing an embodiment of the present invention. The cross-flow fan figure of said one Example form. The blade | wing cross-sectional enlarged view of said one Example form. The blade | wing cross-sectional enlarged view and fan block cross-sectional view of said one Example form. The blade | wing cross-sectional enlarged view of one said Example form, and a fan block cross-sectional enlarged view. The efficiency figure which shows the effect of said one Example form. The efficiency figure which shows the effect of said one Example form. The characteristic view which shows the performance of said one Example form.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cross-flow fan, 2 ... Cosmetic frame, 3 ... Front grille, 4 ... Top grill, 5 ... Filter, 6 ... Heat exchanger, 7 ... Casing, 8 ... Vertical wind direction plate, 9 ... Horizontal wind direction plate, 10 ... Motor, DESCRIPTION OF SYMBOLS 11 ... Nose, 12 ... Blade | wing, 13 ... Disk, 14 ... End face disk, 15 ... End face disk with boss | hub, 16 ... Boss, 17 ... Warp line, 18 ... Pressure surface

Claims (3)

  In the air conditioner having a cross-flow fan in the indoor unit, the warp line indicating the thickness center of the cross section of the blade of the cross-flow fan includes two arcs, and the warp directions of the respective arcs are reversed to each other, and the flow path between the blades An air conditioner in which the thickness of the blade is set so that the width is in the range of 60 to 80% on the outer diameter side with respect to the inner diameter side.   In an air conditioner including a cross-flow fan in an indoor unit, the pressure surfaces of the blades constituting the cross-flow fan are made to coincide with the rotation axis direction, and the flow path width between the blades is 60 on the outer diameter side with respect to the inner diameter side. Air conditioner with blade thickness set to be in the range of ~ 80%.   In the air conditioner including a cross-flow fan in the indoor unit, the warp line indicating the thickness center of the cross section of the blade of the cross-flow fan includes two arcs, and the warp directions of the respective arcs are reversed to each other, so that the pressure surface of the blade The air conditioner in which the thickness of the blades is set so that the flow path width between the blades is in the range of 60 to 80% on the outer diameter side with respect to the inner diameter side.

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