JP6134944B2 - Centrifugal blower and vehicle air conditioner - Google Patents

Description

  The present invention relates to a centrifugal blower including a centrifugal multiblade fan and a scroll casing, and a vehicle air conditioner employing the centrifugal blower.

  In this type of centrifugal blower, it is known that noise is generated when the air blown from the centrifugal multiblade fan collides with the nose portion of the scroll casing. Such noise is particularly noticeable when the ratio (H / D) of the blade height (H) to the fan diameter (D) of the centrifugal multiblade fan is small (H / D ≦ 0.5). Become. In addition, a nose part is a site | part which connects the winding start side and winding end side in a scroll casing.

  As a technique for suppressing the generation of this noise, for example, Patent Document 1 proposes a configuration in which a gap (nose gap) between a nose portion and a centrifugal multiblade fan is enlarged. In addition, according to the experimental result of patent document 1, when the nose gap is set to 0.07 or more of the fan diameter D, an effect of suppressing noise generation is recognized.

JP 2002-371997 A

  By the way, the cause of the noise generated by the centrifugal blower is not only that the air blown out from the centrifugal multiblade fan collides with the nose portion of the scroll casing, but also due to air separation between adjacent blades of the centrifugal multiblade fan. Also occurs. Note that the separation of air between the blades becomes more prominent as the flow velocity of the air flowing between the blades increases.

  In this regard, the prior art (Patent Document 1) is not particularly focused on, and aims to reduce noise when air blown from the centrifugal multiblade fan collides with the nose portion.

  Therefore, in order to further reduce the noise of the centrifugal fan, the present inventors introduced air into the scroll casing having a correlation with the flow velocity of the air flowing between the blades in the centrifugal fan according to the prior art. The suction flow rate Va was investigated.

  In this investigation, as shown in FIG. 9, the gap (nose gap Ng) between the nose portion 122 of the scroll casing 120 and the centrifugal multiblade fan 110 having a large number of blades 111 is 0.125 times the fan diameter D. The centrifugal blower (examination example) was used.

  FIG. 10 shows experimental results when air is introduced from the axial direction of the centrifugal multiblade fan 110 into the suction port 121 in the scroll casing 120. As shown in FIG. 10, the suction flow rate Va of the air introduced into the scroll casing 120 decreases in the suction region A where the winding angle θ from the nose portion 122 in the suction port 121 is small, and the opposite winding angle θ is It has been found that it increases in the large suction area B. The winding angle θ is an angle formed in the circumferential direction from the beginning of winding of the scroll casing 120 around the axis O of the centrifugal multiblade fan 110.

  The cause of the decrease in the suction flow rate Va in the suction region A may be that the cross-sectional area of the air channel in the scroll casing 120 is small and the ventilation resistance becomes larger than that in the suction region B. Such a decrease in the suction flow rate Va in the suction region A also occurs when the gap Ng between the nose portion 122 and the centrifugal multiblade fan 110 is set to a range of 0.07 times the fan diameter D or more.

  As described above, in the centrifugal blower according to the study example, even if the noise caused by the air blown from the centrifugal multiblade fan 110 colliding with the nose portion 122 can be suppressed, it is caused by the variation in the suction flow rate Va. Noise has not been addressed and there is still room for improvement.

  An object of this invention is to provide the centrifugal air blower which can suppress generation | occurrence | production of the noise resulting from the dispersion | variation in suction flow volume in view of the said point.

In order to achieve the above object, according to the first aspect of the present invention, a plurality of blades (221) are provided around the rotating shaft (23a), and the air sucked from one axial end of the rotating shaft is radially outward. The centrifugal multiblade fan (22) that blows out and the centrifugal multiblade fan are housed, and a spiral air flow path (21a) through which the air blown from the centrifugal multiblade fan flows is formed, and one axial end of the rotary shaft A scroll casing (21) formed with an air suction port (211) for sucking air from the side, and a guide means (14) for setting a main flow of introduced air introduced into the air suction port. And the space | interval (Ng) from a centrifugal multiblade fan to the nose part (213) of a scroll casing is 0.07 times or more and 0.25 times or less of a fan diameter, and a guide means is an air suction inlet. It is provided on the upstream side of the air flow, and is characterized in that it is set so as to guide the main flow of the introduced air to the region on the nose portion side of the suction region where the winding angle from the nose portion at the air suction port becomes an acute angle. .

  As described above, if the configuration is such that the main flow of the introduced air is guided to the nose portion side region in the air suction port having a large ventilation resistance, the introduction air into the suction region having a small ventilation resistance compared to the nose portion side region. Can be prevented from flowing unevenly (see FIG. 6). As a result, the flow velocity of air flowing between adjacent blades in the centrifugal multiblade fan is made uniform, so that noise is suppressed and fan efficiency is improved (see FIGS. 7 and 8).

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is an overall configuration diagram of a vehicle air conditioner according to an embodiment. It is a typical perspective view of the inside / outside air switching box and the centrifugal blower according to the embodiment. It is typical sectional drawing of the inside / outside air switching box and centrifugal blower concerning an embodiment. It is a top view of the centrifugal blower according to the embodiment. It is explanatory drawing for demonstrating the suction direction of the air of a centrifugal air blower. It is a chart which shows distribution of the suction flow of the centrifugal blower concerning an embodiment. It is a graph which shows the relationship between the air suction direction and specific noise of the centrifugal blower which concerns on embodiment. It is a graph which shows the relationship between the air suction direction and fan efficiency of the centrifugal blower which concerns on embodiment. It is explanatory drawing for demonstrating the centrifugal blower which concerns on the example of examination. It is a graph which shows distribution of the suction | inhalation flow volume of the centrifugal fan which concerns on an examination example.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the vehicle air conditioner 1 is housed inside a dashboard disposed in front of the vehicle interior. The vehicle air conditioner 1 of the present embodiment includes an inside / outside air switching box 10, a centrifugal blower 20, and an air conditioning unit 30 as main components.

  The inside / outside air switching box 10 is provided on the upstream side of the air flow of the centrifugal blower 20, and the introduction air introduced into the air suction port 211 of the centrifugal blower 20 is either the vehicle interior air (inside air) or the vehicle interior air (outside air). It is an inside / outside air switching means for switching between the two.

  The inside / outside air switching box 10 of the present embodiment includes an inside air introduction port 12 that introduces inside air into the air suction port 211 of the centrifugal blower 20, an air introduction duct 11 in which an outside air introduction port 13 that introduces outside air is formed, and each An inside / outside air switching door 14 for selectively opening and closing the introduction ports 12 and 13 is provided. The position of the inside / outside air switching door 14 is controlled by driving means such as a servo motor (not shown). Details of the inside / outside air switching box 10 will be described later.

  The centrifugal blower 20 blows air introduced through the inside / outside air switching box 10 into the vehicle interior. The centrifugal blower 20 includes, as main components, a centrifugal multiblade fan 22, a scroll casing 21 that houses the centrifugal multiblade fan 22, and an electric motor 23 that rotationally drives the centrifugal multiblade fan 22. In the centrifugal blower 20, an energization amount corresponding to the air volume set by an operation panel (not shown) is supplied to the electric motor 23, and the centrifugal multiblade fan 22 rotates at a rotation speed corresponding to the energization amount. The details of the centrifugal blower 20 will be described later.

  The air conditioning unit 30 includes an air conditioning casing 31 that is connected to the air outlet 212 of the scroll casing 21 and constitutes an air flow path of the air blown from the centrifugal blower 20.

  In the air conditioning casing 31, an evaporator 32 is disposed as a cooling means for cooling the air blown into the room. The evaporator 32 constitutes a well-known refrigeration cycle together with a compressor, a condenser, and a decompressor (not shown). The evaporator 32 is a heat exchanger that cools air by heat-exchanging the low-pressure refrigerant flowing in the refrigeration cycle with the air in the air-conditioning casing 31 and evaporating it.

  On the downstream side of the evaporator 32 in the air conditioning casing 31, a heater core 33 is disposed as a heating means for heating the air blown into the room. The heater core 33 is a heat exchanger for heating that heats air that is blown into the vehicle interior using engine cooling water that cools a vehicle engine (not shown) as a heat source.

  In addition, a bypass passage 34 is formed on the side of the heater core 33 in the air conditioning casing 31 so as to flow air that blows around the heater core 33 into the room. An air mix door 35 that adjusts the air volume ratio between the air volume that passes through the heater core 33 and the air volume that passes through the bypass passage 34 is disposed on the upstream side of the air flow of the heater core 33. The position of the air mix door 35 is controlled by driving means such as a servo motor (not shown).

  Further, at the most downstream portion of the air flow of the air conditioning casing 31, a defroster outlet 36 that blows air toward the inner surface of the windshield W, a face outlet 37 that blows air toward the upper body of the occupant, and the feet of the occupant A foot outlet 38 for blowing out air is formed.

  Blow switch doors 39 to 41 are disposed on the air flow upstream side of the blow outlets 36 to 38, respectively. In addition, each blowing switching door 39-41 is opened and closed by drive means, such as a servomotor which is not shown in figure.

  Next, details of the inside / outside air switching box 10 and the centrifugal blower 20 of the present embodiment will be described with reference to FIGS. First, the centrifugal blower 20 will be described. The centrifugal multiblade fan 22 of the present embodiment is a fan that blows out air sucked from one axial end of the rotating shaft 23a toward the radially outer side.

  The centrifugal multiblade fan 22 has a plurality of blades 221 disposed around the rotation shaft 23 a of the electric motor 23. Each blade 221 is connected at one end in the axial direction (air suction side) via a side plate 22a, and at the other end in the axial direction is connected to a rotary shaft 23a via a main plate 22b.

  In the centrifugal multiblade fan 22, the ratio (L / D) of the chord length (L) of the blade 221 to the fan diameter (D) is 0.09 times or more and 0.20 times or less (in this embodiment, L /D=0.14) The fan specifications are set. The chord length (L) of the blade 221 is the difference between the outer radius and the inner radius of the centrifugal multiblade fan 22.

  The scroll casing 21 accommodates the centrifugal multiblade fan 22 and constitutes a spiral air flow path 21 a through which air blown from the centrifugal multiblade fan 22 flows. In the scroll casing 21, an air suction port 211 is opened on the opposite side of the electric motor 23 in the axial direction of the rotating shaft 23 a, and a bell mouth 211 a is formed at the opening edge of the air suction port 211. The scroll casing 21 has an air outlet 212 communicating with the air conditioning casing 31 on the downstream side of the air flow from the winding end portion.

  Furthermore, the scroll casing 21 of the present embodiment has an outer peripheral diameter and a height along the rotating shaft 23a that are gradually enlarged, and the flow path cross-sectional area of the air flow path 21a is changed from the air flow upstream side to the downstream side (air blowing The outlet 212 is larger.

  The scroll casing 21 has an arcuate nose portion 213 that is a portion where the winding start side and the winding end side of the scroll casing 21 overlap.

  Here, the centrifugal blower 20 of the present embodiment has a nose portion 213 and a centrifugal multiblade fan 22 in order to suppress noise generated when the air blown from the centrifugal multiblade fan 22 collides with the nose portion 213 of the scroll casing 21. The gap (nose gap) Ng between the two is enlarged. Specifically, in the centrifugal blower 20, the gap (nose gap Ng) between the nose portion 213 and the centrifugal multiblade fan 22 is 0.07 times or more and 0.25 times or less of the fan diameter D (in this embodiment, , 0.125 times).

  The reason why the nose gap Ng is 0.07 times or more the fan diameter D is that the cross-sectional area of the air flow passage 21a is rapidly reduced between the winding end side and the winding start side of the scroll casing 21. This is to suppress noise caused by the occurrence of the noise.

  Moreover, the reason why the nose gap Ng is made 0.25 times or less of the fan diameter D is that the flow passage cross-sectional area of the air flow passage 21a becomes too large between the winding end side and the winding start side of the scroll casing 21. This is to prevent air from flowing again from the winding end side to the winding start side due to the above. Thereby, the noise by the deterioration of the ventilation performance by the ventilation pressure fall and the collision with the air blown from the centrifugal multiblade fan 22 and the air which flows into the winding start side from the winding end side can be suppressed.

  Next, the inside / outside air switching box 10 will be described. As shown in FIGS. 2 and 3, the inside air inlet 12 is opened in the wall surface 11 a extending vertically of the air introduction duct 11, and the inclined surface 11 b of the air introduction duct 11 is formed. The outside air inlet 13 is open.

  In this embodiment, as shown in FIG. 3, when the inside / outside air switching door 14 closes the outside air introduction port 13, the suction angle formed between the inside / outside air switching door 14 and the opening surface of the air suction port 211 of the centrifugal blower 20. The inclination of the inclined surface 11b is set so that α is about 45 ° (preferable range is 25 ° to 65 °).

  Here, as described in [Problems to be Solved by the Invention], in the centrifugal blower 20 in which the gap between the nose portion 213 and the centrifugal multiblade fan 22 is enlarged, the scroll casing 21 is caused by ventilation resistance or the like. The suction flow rate Va of the introduced air into the inside will be biased.

  Specifically, the suction flow rate Va of the introduced air decreases in a region where the winding angle θ from the nose portion 213 in the air suction port 211 is 0 ° to 45 °, and the winding flow from the nose portion 213 in the air suction port 211. The angle θ tends to increase in a region where the angle is 180 ° to 225 °. As shown in FIG. 4, the “winding angle θ” is the direction of rotation of the centrifugal multiblade fan 22 (reverse to the reference line Ho connecting the center of curvature of the nose portion 213 and the rotational center of the centrifugal multiblade fan 22). (Clockwise).

  Therefore, in the present embodiment, the main flow of the introduced air introduced into the air suction port 211 of the centrifugal blower 20 by the inside / outside air switching door 14 has a winding angle θ from the nose portion 213 in the air suction port 211 of 0 ° to 0 °. It guide | induces to the area | region (suction area | region A of FIG. 4) which becomes 45 degrees. In the present embodiment, the inside / outside air switching door 14 constitutes a guide means for setting a main flow of introduced air introduced into the air suction port 211.

  Specifically, as shown in FIG. 5A, the air introduction duct 11 has a portion where the winding angle θ from the nose portion 213 is 180 ° to 225 ° (in this embodiment, the winding angle θ is 200). Inside air inlet 12 is formed at a portion that becomes °.

  When the outside air introduction door 13 is closed, the inside / outside air switching door 14 is a region on the nose portion 213 side in the suction region where the winding angle θ from the nose portion 213 in the air suction port 211 becomes an acute angle (this embodiment). Is set so that the main flow of the introduced air is guided to a region where the winding angle θ is 20 °.

  In the centrifugal blower 20 of the present embodiment described above, the main flow of the introduced air is guided to the region on the nose portion 213 side in the air suction port 211 having a large ventilation resistance. According to this, compared with the area | region by the side of the nose part 213, it can suppress that introduced air flows in the suction area | region where ventilation resistance is small.

  Here, FIG. 6 is a result of the investigation of the suction flow rate Va of the introduced air into the scroll casing 21 of the centrifugal blower 20 according to the present embodiment. The solid line in FIG. 6 shows the distribution of the suction flow rate Va of the centrifugal blower 20 (this example) according to this embodiment, and the alternate long and short dash line in FIG. 6 shows the suction flow rate of the centrifugal blower 20 according to the study example. The distribution of Va (similar to FIG. 10) is shown.

  As shown in FIG. 6, in the centrifugal blower 20 of the present embodiment, it can be seen that the distribution of the suction flow rate Va of the introduced air into the scroll casing 21 is reduced as compared with the study example.

  Here, the suction flow rate Va has a correlation with the flow velocity of air flowing between adjacent blades 221 in the centrifugal multiblade fan 22, and the distribution of the suction flow rate Va is reduced, so that the centrifugal multiblade fan is reduced. The flow velocity of the air flowing in between the adjacent blades 221 in 22 is made uniform.

  As a result, in the centrifugal blower 20 of the present embodiment, fan efficiency can be improved while suppressing noise. This point will be described with reference to FIGS. FIG. 7 is a chart showing the relationship between the air suction direction and specific noise of the centrifugal blower 20 according to this embodiment, and FIG. 8 is the air suction direction and fan of the centrifugal blower 20 according to this embodiment. It is a graph which shows the relationship with efficiency.

  Here, as shown in FIG. 5A, the circular plot shown in each figure shows the specific noise and fan efficiency when air is introduced when the winding angle θ from the nose portion 213 at the air inlet port 211 is around 20 °. Show. The square plot shows specific noise and fan efficiency when air is introduced when the winding angle θ from the nose portion 213 in the air suction port 211 is around 110 ° as shown in FIG. 5B. The rhombus plot shows specific noise and fan efficiency when air is introduced when the winding angle θ from the nose portion 213 in the air suction port 211 is around 200 ° as shown in FIG. The triangular plot shows the specific noise and fan efficiency when air is introduced when the winding angle θ from the nose portion 213 in the air inlet port 211 is around 290 ° as shown in FIG. The definition of specific noise and the like is based on JIS, and the test method is based on JIS.

  When the main flow of the introduced air is guided to a region where the winding angle θ from the nose portion 213 in the air suction port 211 is about 20 ° as in the present embodiment, the specific noise is shown as shown by the circular plot in FIG. As a result, the minimum value of was the smallest compared to the other configurations. Thereby, it turns out that noise can be suppressed by setting it as the structure which guide | induces the mainstream of introduction air to the area | region where the winding angle (theta) from the nose part 213 in the air suction inlet 211 becomes 20 degree vicinity (0 degree-45 degree).

  Further, as in the present embodiment, when the configuration is such that the main flow of the introduced air is guided to a region where the winding angle θ from the nose portion 213 in the air suction port 211 is about 20 °, as shown by the circular plot in FIG. The result that the maximum value of the fan efficiency was the highest compared to other configurations was obtained. Accordingly, it is understood that the fan efficiency can be improved by adopting a configuration in which the main flow of the introduced air is guided to a region where the winding angle θ from the nose portion 213 in the air suction port 211 is around 20 ° (0 ° to 45 °). .

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, In the range described in the claim, it can change suitably. For example, various modifications are possible as follows.

  (1) In the above-described embodiment, when the outside air inlet 13 is closed, the main flow of the introduced air introduced into the air inlet 211 of the centrifugal blower 20 is wound from the nose portion 213 in the air inlet 211. Although the example led to the region where the angle θ is 0 ° to 45 ° has been described, the present invention is not limited to this. For example, when the inside air inlet 12 is closed, the main flow of the introduced air introduced into the air suction port 211 of the centrifugal blower 20 has a winding angle θ from the nose portion 213 in the air suction port 211 of 0 ° to 45 °. You may make it guide | lead to the area | region which becomes °.

  (2) In the above-described embodiment, the example in which the inside / outside air switching door 14 is functioned as a guide means for setting the main flow of the introduced air introduced into the air suction port 211 has been described. However, the present invention is not limited to this. For example, a guide plate is separately arranged on the upstream side of the air suction port 211 of the centrifugal blower 20, and the main flow of the introduced air introduced into the air suction port 211 by the guide plate is changed in the air suction port 211. You may make it guide | induced to the area | region where winding angle (theta) from the nose part 213 becomes 0 degrees-45 degrees. In this case, the centrifugal blower 20 of the present invention may be applied not only to the vehicle air conditioner 1 but also to a stationary air conditioner used in a home or factory.

  (3) In the above-described embodiment, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Needless to say.

  (4) In the above-mentioned embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly indicated that it is essential and clearly in a specific number in principle. It is not limited to the specific number except in a limited case.

  (5) In the above-described embodiment, when referring to the shape, positional relationship, etc. of the component, etc., unless otherwise specified, the shape is limited to a specific shape, positional relationship, etc. in principle. The positional relationship is not limited.

14 Inside / outside air switching door (guide means)
20 Centrifugal Blower 21 Scroll Casing 211 Air Suction Port 22 Centrifugal Multiblade Fan 23a Rotating Shaft

Claims (4)

A centrifugal multiblade fan (22) having a large number of blades (221) around the rotating shaft (23a), and blowing out the air sucked from one axial end of the rotating shaft toward the radially outer side;
The centrifugal multiblade fan is housed, and a spiral air flow path (21a) through which the air blown out from the centrifugal multiblade fan flows is formed, and an air suction port for sucking air from one axial end side of the rotating shaft ( 211) formed with a scroll casing (21);
Guide means (14) for setting a main flow of introduced air introduced into the air suction port,
An interval (Ng) from the centrifugal multiblade fan to the nose portion (213) of the scroll casing is 0.07 times or more and 0.25 times or less of the fan diameter,
The guide means is provided on the air flow upstream side of the air suction port, and out of the suction region where the winding angle from the nose portion at the air suction port becomes an acute angle, the guide air is introduced into the region on the nose portion side. A centrifugal blower characterized in that it is set to guide the mainstream.   The said guide means is set so that the mainstream of the said introductory air may be guide | induced to the suction area | region where the winding angle ((theta)) from the said nose part in the said air suction port becomes 0 degree-45 degrees. Item 2. The centrifugal blower according to Item 1.   In the centrifugal multiblade fan, a ratio (L / D) of a blade chord length (L) to a fan diameter (D) is 0.09 times or more and 0.20 times or less. The centrifugal blower according to claim 1 or 2. The centrifugal blower (20) according to any one of claims 1 to 4,
An air introduction duct (11) provided on the upstream side of the air suction port and formed with an inside air introduction port (12) for introducing vehicle interior air and an outside air introduction port (13) for introducing vehicle exterior air; Prepared,
The guide means includes an inside / outside air switching door (14) that opens and closes the inside air introduction port and the outside air introduction port, and when closing one of the inside air introduction port and the outside air introduction port, An air conditioner for a vehicle, wherein the air conditioner is set so as to guide the main flow of the introduced air to a region on the nose portion side in the air suction port.

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