JP2015052279A - Indoor equipment of air conditioner and air conditioner using indoor equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide indoor equipment of an air conditioner including a cross flow fan reducing noise so as to overcome a problem that a frequency with an average pitch is apt to be superior, noise at a specified frequency is increased and comfort is not improved when an angular clearance between similar locations on adjoining pairs of blades is determined by a prescribed mathematical expression.SOLUTION: Indoor equipment of an air conditioner of this invention comprises an indoor heat exchanger, a cross flow fan having several fan blades arranged at a downstream side of the indoor heat exchanger and of which outer diameter shape is wave-shape or saw-tooth shape, and the fan blades are arranged at positions where a blade pitch of the cross flow fan is increased or decreased in a substantial periodical manner.

Description

  The present invention relates to an air conditioner.

  U.S. Pat. No. 6,057,049 is an improved impeller for a horizontal fan, in which the angular spacing between similar locations on adjacent pairs of vanes is determined by a predetermined formula. In the impeller for a horizontal fan described in Patent Document 1, the angular interval between similar locations on adjacent pairs of blades becomes a period expressed by a trigonometric function, and the static and dynamic balance is lost. Therefore, the noise of the blade speed sound can be effectively reduced.

JP-A-6-294396

  However, the impeller described in Patent Document 1 has a tendency that the frequency due to the average pitch is dominant, noise at a specific frequency increases, and there is a problem that comfort is not improved.

  The objective of this invention is providing the indoor unit of the air conditioner provided with the cross-flow fan which reduced the noise.

  An indoor unit of an air conditioner according to the present invention includes an indoor heat exchanger, and a cross-flow fan that is provided downstream of the indoor heat exchanger and has a plurality of fan blades whose outer diameter shape is corrugated or saw-shaped. The blades are arranged at positions where the blade pitch of the cross-flow fan increases or decreases approximately periodically.

  ADVANTAGE OF THE INVENTION According to this invention, the indoor unit of the air conditioner provided with the cross-flow fan which reduced the noise can be provided.

It is a cycle lineblock diagram of the air harmony machine concerning a 1st embodiment. It is a front lineblock diagram when a part of indoor unit of the air harmony machine concerning a 1st embodiment is seen through. It is a section lineblock diagram of the indoor unit of the air harmony machine concerning a 1st embodiment. It is a perspective view of the cross-flow fan 1 block of the indoor unit of the air conditioner which concerns on 1st Embodiment. It is an arrangement | sequence of the blade pitch of the fan blade of the cross-flow fan of the indoor unit of the air conditioner which concerns on 1st Embodiment. It is a measurement result of the relationship between the frequency of the indoor unit of the air conditioner which concerns on the comparative example 1 and the comparative example 2, and a noise. It is a measurement result of the relationship between the frequency of the indoor unit of the air conditioner which concerns on the comparative example 1 and the comparative example 3, and a noise. It is a measurement result of the relationship between the frequency of the indoor unit of the air conditioner which concerns on 1st Embodiment and Comparative Example 3, and noise. It is a numerical analysis result of the instantaneous value of pressure distribution in the stabilizer concerning comparative example 3. It is a numerical analysis result of the instantaneous value of pressure distribution in the stabilizer concerning a 1st embodiment. It is explanatory drawing explaining the flow of the wind speed on a fan blade at the time of approaching the stabilizer which concerns on 1st Embodiment. It is explanatory drawing explaining the flow of the wind speed on a fan blade at the time of approaching the stabilizer which concerns on 2nd Embodiment. It is explanatory drawing explaining the flow of the wind speed on a fan blade at the time of approaching the stabilizer which concerns on 3rd Embodiment.

  Embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a cycle configuration diagram of the air conditioner according to the first embodiment. During the cooling operation, the high-temperature and high-pressure refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 through the four-way valve 2. The refrigerant flowing into the outdoor heat exchanger 3 is condensed and becomes liquid refrigerant by exchanging heat with outdoor air sent by the outdoor blower fan 4. The liquid refrigerant passes through the expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant and flows into the indoor heat exchanger 120.
The low-temperature and low-pressure two-phase refrigerant that has flowed into the indoor heat exchanger 120 exchanges heat with indoor air sent by a cross-flow fan (indoor fan) 130. At this time, the indoor air sent to the indoor heat exchanger 120 is cooled by the low-temperature and low-pressure two-phase refrigerant that has flowed into the indoor heat exchanger 120 and is discharged into the room from the outlet. Since the air discharged into the room from the outlet is lower than the temperature of the air at the inlet, the room temperature can be lowered. The refrigerant heat-exchanged in the indoor heat exchanger 120 returns to the compressor 1 again via the four-way valve 2. The compressor 1, the outdoor heat exchanger 3, the outdoor blower fan 4, and the expansion valve 5 are disposed in the outdoor unit, and the indoor heat exchanger 120 and the cross-flow fan 130 are disposed in the indoor unit 100.

  FIG. 2 is a front configuration diagram when a part of the indoor unit of the air conditioner according to the first embodiment is seen through. FIG. 3 is a cross-sectional configuration diagram of the indoor unit of the air conditioner according to the first embodiment. As shown in FIGS. 2 and 3, the indoor unit 100 of the air conditioner according to the present embodiment is provided with a front panel 101 on the front side and an upper surface grill 102 on the upper side, and the front is in operation during operation of the air conditioner. The panel 101 opens at the upper part with the lower part as a fulcrum, sucks air from the front surface and the upper surface as indicated by arrows F1 and F2, and discharges the air toward the outlet 103 as indicated by the arrow F3. A side wind direction plate 104 is provided on the lower surface side of the indoor unit 100, and the air outlet 103 of the indoor unit 100 can be opened and closed as the side wind direction plate 104 rotates.

  A pre-filter 110 attached to a filter frame 111 is provided immediately inside the front panel 101 and the top grill 102. A filter cleaning mechanism 112 is provided outside the pre-filter 110, and dust caught in the eyes of the filter is removed by moving horizontally on the pre-filter 110 while sweeping in the longitudinal direction of the indoor unit 101.

  Inside the pre-filter 110, an indoor heat exchanger 120 including heat exchange fins 128 and a refrigerant pipe 129 is provided as a front-side heat exchanger 122, a rear-side heat exchanger 123, and an auxiliary heat exchanger 124. It is provided to surround. The indoor heat exchanger 120 harmonizes the air sucked from the suction port of the indoor unit 100. Cross-flow fan 130 is provided downstream of the indoor heat exchanger, and has a plurality of fan blades 310. In the present embodiment, the cross-flow fan 130 has a configuration in which a plurality of fan blocks 300 including a plurality of fan blades 310 and a partition plate 320 are connected in the axial direction like the fan blocks 300a and 300b. A cross-flow fan 130 composed of a plurality of fan blades 310 is positioned so as to be sandwiched between a front casing 131 and a back casing 132. A stabilizer 201 and a rear guider 202 are formed at the tips of the front casing 131 and the back casing 132, respectively.

  As shown in FIG. 3, the cross-flow fan 130 rotates clockwise, forming a circulation vortex f20 that is characteristic of the cross-flow fan 130, and the wind passing through the indoor heat exchanger 120 is blown out like the main flow f10. Air conditioning is done. Between the adjacent fan blades 310, the inflow air flows into the fan blade 310 as indicated by the inflow air f11a, the inflow air f11b, and the inflow air f11c, and is blown out as indicated by the blowing air f12a, the blowing air f12b, and the blowing air f11c. Wind is discharged from the fan blade 310. The blown air f22a and the suction air f21a blown out near the stabilizer 201 form a circulation vortex f20 unique to the cross-flow fan 130 in the vicinity of the stabilizer 201. The fan blade 130 generates noise by the pressure fluctuation generated at the approaching part as a main sound source at a position approaching the front heat exchanger 122, the stabilizer 201 and the rear guider 202 (hereinafter referred to as “approaching part”).

  FIG. 4 is a perspective view of the cross-flow fan 1 block of the indoor unit of the air conditioner according to the first embodiment. Cross-flow fan 130 is configured by attaching N fan blades 310 to partition plate 320. The fan blades 310 are sequentially arranged at a predetermined angle with respect to the reference 330 (which may be arbitrary since it is symmetrical). In this embodiment, an angle between the outermost diameter points 332 of the adjacent fan blades 310 (hereinafter referred to as “blade pitch”) P (n) (n is a blade number from the reference) is given periodicity. .

  The edge 311 which is the outer peripheral end of the fan blade 310 has a crest 312a to 312d and a trough 313a to 313d, and has a periodic shape (hereinafter referred to as “waveform”) connected by a smooth curve. At this time, since there is no sudden shape change at the edge as will be described later, there is no sudden fluid fluctuation on the edge 311.

  Here, among the cross-flow fans 130, the partition plate 320 has a small contribution to the blowing. Therefore, in the present embodiment, the mountain is in contact with the partition plate 320 at the edge 311 that is the outer peripheral side of the fan blade 310. The structure in which a mountain having a larger fan outer diameter than that of the valley is in contact with the partition plate 320 can compensate for the air volume reduction by the partition plate 320. Therefore, it contributes to fan input reduction and noise reduction by lowering the rotation speed with the same air volume. Further, since the contact area with the partition plate 320 is increased, the strength of the cross-flow fan 130 can be improved.

  FIG. 5 is an array of blade pitches of fan blades of the cross-flow fan of the indoor unit of the air conditioner according to the first embodiment. The horizontal axis of FIG. 5 is the fan blade number when the fan blades 310 are arranged in order (the reference fan blade is arbitrary). The vertical axis in FIG. 5 is the blade pitch P (n). Comparative Example 1 and Comparative Example 2 are cross-flow fans 130 in which the blade pitch P (n) is randomly determined by the fan blade number. Comparative Example 3 and this embodiment are cross-flow fans 130 in which the blade pitch P (n) is periodically increased or decreased (changed) in the order of the fan blade numbers.

  FIG. 6 is a measurement result of the relationship between the frequency and noise of the indoor unit of the air conditioner according to Comparative Example 1 and Comparative Example 2. Comparative Example 1 and Comparative Example 2 are cross-flow fans 130 in which the blade pitch P (n) is randomly determined. The edge of the fan blade 310 of the comparative example 1 is a straight line, and the edge of the fan blade 310 of the comparative example 2 has a waveform shown in FIG.

  The noise of the once-through fan 130 is mainly generated when the fan blade 310 approaches the approaching portion. Therefore, the noise of the cross-flow fan 130 is caused by the period when the fan blade 310 approaches the approaching portion, and is referred to as a blade passing frequency (hereinafter referred to as “BPF”), which is a value obtained by multiplying the rotation speed of the cross-flow fan 130 and the number of fan blades 310. ). Noise with a frequency of BPF is a sound equivalent to a high tone for the human body and may be particularly uncomfortable.

  In Comparative Example 1, the blade pitch P (n) is randomized so that the fan blade 310 approaches the approach portion (until the next fan blade 310 approaches the approach portion after the fan blade 310 approaches the approach portion). Time) is random. According to the cross-flow fan 130 of Comparative Example 1, the frequency of noise in the cross-flow fan 130 can be dispersed.

  However, in Comparative Example 1, as shown in FIG. 6, a plurality of peaks randomly exist in the low frequency region (the region where the frequency is equal to or less than BPF). In the first comparative example, the fan blade 310 approaches the approach portion (the time until the next fan blade 310 approaches the approach portion after the fan blade 310 approaches the approach portion) is random. This is because the pressure applied to the fan blade 310 changes abruptly when passing through the sections sequentially.

  Therefore, as Comparative Example 2, first, the edge of the fan blade 310 was corrugated to try to alleviate the pressure fluctuation applied to the fan blade 310 when the fan blade 310 sequentially passed through the approaching portion.

  However, when the fan blades 310 sequentially pass through the approaching part, the pressure change at the approaching part is abrupt, so that even if the edge of the fan blade 310 is corrugated, the pressure fluctuation can hardly be suppressed. . Therefore, as shown in FIG. 6, Comparative Example 2 did not show a significant noise difference from Comparative Example 1, and the input was not reduced compared to Comparative Example 1.

  FIG. 7 is a measurement result of the relationship between the frequency and noise of the indoor unit of the air conditioner according to Comparative Example 1 and Comparative Example 3. Comparative Example 3 is a cross-flow fan 130 in which the blade pitch P (n) is periodically increased or decreased in the order of fan blade numbers. Comparative example 1 is cross-flow fan 130 in which blade pitch P (n) is randomly determined. In both Comparative Example 3 and Comparative Example 1, the edge of the fan blade 310 is a straight line.

  In Comparative Example 3, by periodically increasing or decreasing the blade pitch P (n), the frequency at which the fan blade 310 approaches the approaching portion is smoothed while suppressing the noise in the cross-flow fan 130 from concentrating on the BPF to some extent. It is changing. Then, the cross-flow fan 130 of the comparative example 3 can suppress the pressure fluctuation in the approach portion as compared with the comparative example 1 that changes at random, resulting in a reduction in noise in the low frequency region. By providing periodicity to the blade pitch P (n), the change in the adjacent blade pitch P (n) becomes smooth, and the change in the adjacent inflow air from the inflow air f11a to f11c in FIG. The change from f12a to f12c also becomes smooth, and the pressure fluctuation applied when each fan blade 310 passes through the approaching part becomes smooth.

  However, in Comparative Example 3, as shown in FIG. 7, compared to Comparative Example 1, the noise with a frequency of BPF was as high as 45 dB. In the cross-flow fan 130 of the comparative example 3, the period when the fan blade 310 approaches the approaching portion increases or decreases. However, the pressure (wind speed) caused by the fan blade 310 approaching the approaching portion is not caused by only one fan blade 310, and is also affected by, for example, the front and rear fan blades 310. Fluctuation is small compared to the period approaching. That is, in Comparative Example 3, the blade pitch P (n) is increased or decreased, but compared with Comparative Example 1 in which the blade pitch P (n) is suddenly changed, there is an effect of reducing noise with a frequency of BPF. There were few results.

  FIG. 8 is a measurement result of the relationship between the frequency and noise of the indoor unit of the air conditioner according to the first embodiment and the comparative example 3. While the edge of the fan blade 310 of Comparative Example 3 is linear, in this embodiment, the shape of the fan blade 310 is a waveform shown in FIG. This embodiment is a cross-flow fan 130 in which the blade pitch P (n) is periodically increased or decreased in the order of the fan blade numbers, as in the third comparative example. As shown in FIG. 8, in the present embodiment, the noise with a frequency of BPF is about 40 dB, which is a result of 5 dB lower than that in Comparative Example 3.

  FIG. 9 is a numerical analysis result of instantaneous values of pressure distribution in the stabilizer according to Comparative Example 3. FIG. 10 shows numerical analysis results of instantaneous values of pressure distribution in the stabilizer according to the first embodiment. 9 and 10, the contour lines of the pressure distribution on the cross-flow fan 130 side of the stabilizer 201 are indicated by dotted lines. FIG. 11 is an explanatory diagram for explaining the flow of the wind speed on the fan blade when approaching the stabilizer according to the first embodiment. The standard of pressure is atmospheric pressure.

  As shown in FIG. 9, in Comparative Example 3, the fan blade 310 has a distribution in which the pressure is locally low near the lower end of the stabilizer 201 (connection portion with the front casing 131), and the pressure increases toward the lower end side of the stabilizer 201. became. This means a large pressure fluctuation, that is, a large sound source, and an increase in the input of the cross-flow fan 130. Further, the contour lines of the pressure distribution of Comparative Example 3 were straight lines parallel to the edge of the fan blade 310.

  On the other hand, as shown in FIG. 10, in this embodiment, compared to Comparative Example 1, the pressure can be increased by about 10 Pa near the lower end of the stabilizer 201. As shown in FIG. 11, by making the edge 311 of the fan blade 310 into a waveform, when the fan blade 310 passes near the stabilizer 201, the wind passing near the mountain 312 where the gap with the stabilizer 201 is narrow is stabilized. A flow is generated that is sucked in an oblique direction toward a valley 313 having a relatively large gap with 201. In other words, this embodiment can create a wind escape path that passes through a space with a narrow gap, and can increase the pressure near the lower end of the stabilizer 201 as compared with the first comparative example.

  In this embodiment, as shown in FIG. 10, the edge 311 is affected by the waveform, and the pressure contour is a waveform. Since the pressure contour line shown in FIG. 10 is a waveform, when the fan blade 310 passes near the stabilizer 201, the wind passing through the vicinity of the mountain 312 where the gap between the fan 201 and the stabilizer 201 is narrow is compared with the gap between the stabilizer 201. It can be seen that a flow sucked in an oblique direction toward the broad valley 313 occurs.

  Although the pressure fluctuation of the fan blade 310 when the fan blade 310 approaches the stabilizer 201 has been described, the fan blade 310 when the fan blade 310 approaches the front heat exchanger 122 and the rear guider 202 which are other approaching portions. Similar pressure fluctuations occur for the pressure fluctuations. Therefore, according to the present embodiment, by making the edge 311 of the fan blade 310 into a waveform, it is possible to reduce noise in which the frequency generated in the vicinity of the approaching portion becomes BPF.

  In the present embodiment, the torque to the fan blade 310 viewed microscopically is dispersed by the diffusion of the velocity distribution in the oblique direction, and the variation thereof changes smoothly. Therefore, the load on the fan blade 310 is reduced, This also contributes to reducing the power of the once-through fan 130.

  When the fan blade 310 does not approach the front heat exchanger 122, the stabilizer 201, and the rear guider 202, the flow is uniform in a direction substantially perpendicular to the edge 311.

  As described above, in the present embodiment, the blade pitch P (n) is changed so as to be a periodic function, and the edge 311 of the fan blade 310 is formed into a waveform, so that it is compared with Comparative Example 1 and Comparative Example 3. Both input and overall noise were reduced in the entire air volume range. For example, at standard (intermediate) airflow in the specification range, input was reduced by -3% and overall noise was reduced by -1 dB.

  Note that extremely fine dust smaller than the filter lattice of the pre-filter 110 may pass through the indoor heat exchanger 120 and adhere to the fan blade 310. When used over time, it tends to adhere to the edge 311 and reduce the cleanliness of the air conditioner. If the change is not smooth, flow disturbance is likely to occur. When the wind flow on the fan blade 310 is disturbed, many small vortex flows are formed. In this case, the possibility that dust circulates in the vortex and adheres to the wall surface of the fan blade 310 increases. Further, when the change in the wind flow on the fan blade 310 is abrupt, the dust cannot follow the rapid change in the wind flow, and the possibility of adhering to the wall surface of the fan blade 310 increases. In the present embodiment, since the edge 311 of the fan blade 310 is wavy, the wind speed at the edge 311 is distributed and the generation of vortices can be suppressed. Furthermore, since the increase and decrease of the wind speed and the direction change are smooth due to the wave shape, a rapid change in the flow of the wind on the fan blade 310 can be suppressed. As a result, when used over time, the present embodiment was able to reduce the amount of attached dust by 10% compared to Comparative Example 1. Therefore, according to the cross-flow fan 130 of this embodiment, it can also contribute to the improvement of cleanliness.

  In particular, since the wavy peaks and valleys are composed of smooth curves, the above-described oblique wind changes smoothly with a large curvature even at the peak portions of the peaks and valleys, so the loss and load are low. Contributes to reduced input, reduced noise, and improved cleanliness.

  Further, the waveform of the edge 311 of the fan blade 310 may be constituted by a complete cycle, but in a cycle with a change, it is preferable to avoid an increase in specific frequency noise that is likely to occur in the complete cycle. For example, it is desirable that the ratio of the peak side to the valley side is 1: 1 or more, for example, about 1: 2. The waveform of the edge 311 of the fan blade 310 includes a case where the change includes a certain period.

  The blade pitch P (n) may be on the complete periodic pitch 401, but the blade pitch P (n) that perfectly harmonizes tends to have a specific frequency. Furthermore, if the deviation is constant, the harmony is increased and the noise is increased. Making the blade pitch P (n) a periodic function includes a case where there is a slight deviation from the periodic function.

  As the period of the blade pitch P (n) is smaller, the noise in the low frequency region can be reduced, but the noise in the BPF tends to stand up. On the other hand, the smaller the period of the waveform of the edge 311 of the fan blade 310, the greater the amount of wind flowing from each mountain 312 toward the valley 313, and the greater the noise reduction effect of the BPF. As the number decreases, the effect of suppressing vortices that cause noise in the low frequency range is reduced.

  That is, it is desirable to determine the waveform period of the edge 311 of the fan blade 310 based on the period of the blade pitch P (n) in consideration of the noise in the low frequency range and the noise in the BPF. In the present embodiment, the blade pitch P (n) is 2 periods as shown in FIG. 5, and the edge 311 of the fan blade 310 is 3 periods as shown in FIG. The waveform period of the edge 311 of the fan blade 310 is preferably increased or decreased within a range of about two periods with respect to the period of the blade pitch P (n). In other words, the number of peaks or valleys in the waveform of the edge 311 of the fan blade 310 is desirably within a range of ± 2 with respect to the period of the blade pitch P (n).

  Moreover, although the embodiment in which the distance between the peak 312 and the valley 313 is constant is shown, the configuration is not limited to this, and a configuration equivalent to the change in the blade pitch P (n) may be used. If the range of the change in the period is within twice, the same effect as the blade pitch P (n) can be obtained. That is, if the period of the blade pitch P (n) is large, the wind cannot follow the change in the edge shape or the change in the pitch. Further, if the period of the blade pitch P (n) is small, the edge 311 approaches a straight line and pressure fluctuation or speed fluctuation increases, and input, noise, and dust adhesion deteriorate.

  When the change in the blade pitch P (n) is less than one cycle, the blade pitch P (n) changes abruptly when returning from the Nth to the first fan blade, causing wind disturbance. Further, when the change in the blade pitch P (n) is 6 cycles or more, the change in the adjacent blade pitch P (n) becomes abrupt, which causes the wind to be disturbed. Therefore, it is desirable that the change in the blade pitch P (n) be 1 cycle or more and 5 cycles or less (a cycle smaller than 6 cycles).

  Furthermore, in this embodiment, as shown in FIG. 5, the fan blades are arranged so that the change of the blade pitch P (n) becomes a sine curve for two cycles. When the change in the blade pitch P (n) is two cycles, in the main flow f10 in FIG. 3, the pitch between the fan blade 310 located on the suction side of the main flow f10 and the fan blade 310 located on the blowout side can be made closer.

  For example, when the change in blade pitch P (n) is two cycles, when the blade pitch P (n) between the outermost diameter points 332 of adjacent fan blades 310 on the suction side is narrow, the blowout at a position shifted by 180 degrees The blade pitch P (n) on the side is also narrow. Further, when the blade pitch P (n) on the suction side is wide, the blade pitch P (n) on the blowout side, which is a position shifted by 180 degrees, is also wide. That is, the suction side and suction side blade pitch P (n) of the once-through fan 130 can be made closer to each other, the pressure change between the suction side and the outlet side can be reduced, and noise and loss can be reduced.

  Further, in the case of three cycles, the flow field of the cross-flow fan 130 corresponds to the division into three regions of the circulating vortex in addition to suction and discharge, which contributes to input reduction.

  The amplitude a and the amplitude b of the blade pitch P (n) shown in FIG. 5 are preferably different. The difference between the amplitude a and the amplitude b is preferably 0 or more and 1/10 or less of the average pitch 360 / N.

  Although the blade pitch P (n) is periodic, as shown in FIG. 5, the blade pitch P (n) may be shifted by a predetermined angle dP (n) from 401, which is a guide for complete periodic arrangement when the average angle is 2π / N. . Even if the predetermined angle dP (n) is shifted, the blade pitch P (n) changes smoothly, and the efficiency of the cross-flow fan 130 can be improved similarly. That is, the present invention is not limited to the case where the fan blades 310 are arranged so that the blade pitch P (n) becomes a complete periodic function like a sine curve or a cosine curve. If the deviation of the nth blade is a predetermined angle dP (n), the predetermined angle dP (n) is preferably 0 or more and 1/20 or less of the average blade pitch 360 / N. However, if the change in the adjacent blade pitch P (n) is not smooth, there is no effect. As a smoothing range, it is desirable that the difference between adjacent blade pitches P (n) is 1/20 or more and 1/3 or less with respect to 360 / N which is an average blade pitch.

  As shown in FIG. 5, the difference dL between the straight line 313 connecting the peaks and the straight line 314 connecting the valleys is a constant embodiment. However, the present invention is not limited thereto. You may change the size. The range of large and small changes should be within twice. The effect at this time can avoid an increase in noise due to perfect periodicity, as well as a change in period in the blade pitch P (n), and contributes to noise reduction.

(Second Embodiment)
In the present embodiment, description of the same components as those in the first embodiment is omitted. FIG. 12 is an explanatory view illustrating the flow of wind speed on the fan blade when approaching the stabilizer according to the second embodiment. In the first embodiment, the case where the edge 311 of the fan blade 310 is corrugated has been described. However, in the present embodiment, the edge 311 of the fan blade 310 has a plurality of triangular protrusions as shown in FIG. It has a serrated shape.

  Also in the present embodiment, it is possible to create a wind escape path that passes through a space where the gap is narrow, the pressure can be increased near the lower end of the stabilizer 201, and noise with a frequency of BPF can be reduced.

  In the present embodiment, the torque to the fan blade 310 viewed microscopically is dispersed by the diffusion of the velocity distribution in the oblique direction, and the variation thereof changes smoothly. Therefore, the load on the fan blade 310 is reduced, This can also contribute to reducing the power of the once-through fan 130.

(Third embodiment)
In the present embodiment, description of the same components as those in the first embodiment is omitted. FIG. 13 is an explanatory diagram for explaining the flow of the wind speed on the fan blade when approaching the stabilizer according to the third embodiment. In the first embodiment, the case where the edge 311 of the fan blade 310 is corrugated has been described, but in this embodiment, the edge 311 of the fan blade 310 has a plurality of triangular protrusions as shown in FIG. It has a serrated shape.

  Also in the present embodiment, it is possible to create a wind escape path that passes through a space where the gap is narrow, the pressure can be increased near the lower end of the stabilizer 201, and noise with a frequency of BPF can be reduced.

  In the present embodiment, the torque to the fan blade 310 viewed microscopically is dispersed by the diffusion of the velocity distribution in the oblique direction, and the variation thereof changes smoothly. Therefore, the load on the fan blade 310 is reduced, This can also contribute to reducing the power of the once-through fan 130.

DESCRIPTION OF SYMBOLS 100 ... Indoor unit, 120 ... Indoor heat exchanger, 122 ... Front heat exchanger, 130 ... Cross-flow fan, 131 ... Front casing, 201 ... Stabilizer, 132 ... Back casing, 202 ... Rear guider, 310 ... Fan blade, 311 ... Edge , 312 ... mountain, 313 ... valley

Claims (6)

An indoor heat exchanger,
A cross-flow fan provided downstream of the indoor heat exchanger and having a plurality of fan blades whose outer diameter shape is corrugated or saw-shaped,
The fan blade is an indoor unit of an air conditioner arranged at a position where the blade pitch of the cross-flow fan increases or decreases substantially periodically.   The indoor unit of an air conditioner according to claim 1, wherein the increase and decrease of the blade pitch of the cross-flow fan is a substantially periodic function of 1 to 5 cycles.   The indoor unit of an air conditioner according to claim 2, wherein the increase or decrease of the blade pitch of the cross-flow fan is a substantially periodic function of two periods or four periods. The outer diameter shape of the fan blade is a wave shape or a saw shape having a plurality of peaks or valleys,
The indoor unit of an air conditioner according to claim 2, wherein the number of the peaks or valleys is within a range of ± 2 with respect to a period of a blade pitch of the cross-flow fan. The cross-flow fan has a partition plate to which the fan blade is attached,
The outer diameter shape of the fan blade is a corrugated or saw shape having a plurality of peaks,
The indoor unit of an air conditioner according to claim 1, wherein the mountain is in contact with the partition plate. An indoor unit of an air conditioner according to any one of claims 1 to 5,
An air conditioner provided with a compressor, an expansion mechanism, and an outdoor unit having an outdoor heat exchanger.