JPS61210294A - Blower - Google Patents

Abstract

PURPOSE:To reduce noise of a vortex flow blower by forming arc shaped grooves along the rotational direction of the runner of the blower on at least one of the flat surface of the runner or the blower casing. CONSTITUTION:In a vortex flow blower, recessed grooves 7 are formed on a flat surface 222 on the inner wall of a case lid member 22. Recessed groves 7 are formed in the shapes of several rings with some intervals and concentrically with the center O1 which corresponds to the rotation shaft of the runner 1. Recessed grooves may be formed on the flat surface 104 of the runner 1 or on the flat part 212 of a case member 21. Accordingly, it is possible to reduce the noise in the scope of metallic sound without causing the lowering of pressure on the shut-off action of the inlet or discharge pipes.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は、側溝原理による環状の送風機に関し、羽根車
の側面またはこれを収納するケーシングの内壁面の少な
くとも一方に、回転方向に沿う凹溝を設けることにより
、吸入管或いは吐出管の締切動作等に対して、圧力の低
下等を招くことなく、耳障りな金属音領域の騒音を、簡
単かつ確実に低減させるようにしたものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an annular blower based on the gutter principle, in which a concave groove is provided on at least one of the side surface of the impeller or the inner wall surface of a casing housing the impeller along the direction of rotation. As a result, the noise in the harsh metallic sound region can be easily and reliably reduced without causing a drop in pressure or the like during the closing operation of the suction pipe or discharge pipe.

この種の送風機は、経済性に富み、取扱いが容易で、比
較的高い吐出圧力及び吸引力が得らると言う長所があり
、その用途が著しく拡大されつつある０例えば、吐出圧
力の利用としては、空気輸送、曝気、攪拌などの従来の
用途から、紙板の浮上げ（ホバークラフト式）或いは低
圧シリンダの駆動等の用途まで拡大されつつあり、吸引
力の利用用としては、フィルム吸着、真空ロボットハン
ド或いは真空エアチャー２り等のように、−従来。This type of blower has the advantages of being economical, easy to handle, and able to obtain relatively high discharge pressure and suction power, and its applications are rapidly expanding. is being expanded from conventional uses such as pneumatic transportation, aeration, and stirring to applications such as levitating paper boards (hovercraft type) and driving low-pressure cylinders. - Conventional, such as hand or vacuum air blower.

真空装置を用いていた分野まで　用途が拡大されつつあ
る。Applications are expanding to include fields that previously used vacuum equipment.

従来の技術 第５図は従来のこの種の送風機の正面部分欠損図、第６
図は同じくその側面図である０図において、■は羽根車
、２はケーシング、３は電動機、４は吸入管、５は吐出
管である。Conventional technology Fig. 5 is a partially cutaway front view of a conventional blower of this type;
In Figure 0, which is also a side view, ■ is an impeller, 2 is a casing, 3 is an electric motor, 4 is a suction pipe, and 5 is a discharge pipe.

羽根車１はアルミ鋳物等の成形体とじて形成され、円形
状の支持基体１０１の外周に多数の羽根１０２を間隔を
おいて突設した構造となっている。The impeller 1 is formed as a molded body of aluminum casting or the like, and has a structure in which a large number of blades 102 are protruded from the outer periphery of a circular support base 101 at intervals.

そして、全体をケーシング２で覆うと共に、中心部に電
動機３の回転軸３１を取付は固定し、ケーシング２の内
部で回転させるようになっている。The whole is covered with a casing 2, and a rotating shaft 31 of an electric motor 3 is fixedly attached to the center and rotated inside the casing 2.

羽根１０２を突設した外周面よりは内径側の基体１０１
の両側面には、平面部１０３及び１０４を設けである。The base body 101 is located on the inner diameter side of the outer circumferential surface on which the blades 102 are protruded.
Flat parts 103 and 104 are provided on both sides of the board.

なお、羽根１０２の中間部に突起１０５を設けた両羽根
型の他に、Ｌ述のような突起ＩＱ５を持たず１片面を閉
塞した片羽根型のものも良く知られている。In addition to the double-blade type in which the protrusion 105 is provided in the middle of the blade 102, a single-blade type in which one side is closed without the protrusion IQ5 as described in L is also well known.

ケーシング２は、アルミ鋳物等の成形体で成り、電動機
３にネジ止め等の手段によって一体的に取付固定された
ケース部材２１と、このケース部材２１の前面を閉塞す
るようにして、ネジ止め等の手段によって取付は固定さ
れるケース缶部材２２との組合せで形成される。ケース
部材２１とケース蓋部材２２の外周部には、第７図及び
第８図に示すように、互いに組合わせた場合に、羽根車
１の羽根１０２の回転する環状空間６が形成されるよう
に、椀状の凹部２１１　、２２１を形成すると共に、四
部２１１　、２２１より内径側の内壁面に、羽根車１の
支持基体ｌｏｔの側面に形成された平面部１０３　、１
０４と僅かのクリアランスｄｌ　を隔てて対面する平面
部２１２　、２２２を形成しである。平面部２１２　、
２２２の下端部２１３　、２２３は凹部２１１　、２２
１を区画するように外周部まで延長され、その両側で前
述の吸入管４及び吐出管５を連通させである。The casing 2 is made of a molded body such as an aluminum casting, and includes a case member 21 that is integrally attached and fixed to the electric motor 3 by means such as screws, and a case member 21 that closes the front surface of the case member 21 and is fixed to the electric motor 3 by means such as screws. The attachment is formed in combination with the case can member 22 to which it is fixed. As shown in FIGS. 7 and 8, the outer peripheries of the case member 21 and the case lid member 22 are arranged so that, when they are combined with each other, an annular space 6 is formed in which the blades 102 of the impeller 1 rotate. In addition, bowl-shaped recesses 211 and 221 are formed, and flat parts 103 and 1 are formed on the side surfaces of the support base lot of the impeller 1 on the inner wall surface on the inner diameter side of the four parts 211 and 221.
04 and are formed with flat portions 212 and 222 facing each other with a slight clearance dl. Planar part 212,
The lower ends 213 and 223 of 222 are the recesses 211 and 22
It extends to the outer periphery so as to partition 1, and the above-mentioned suction pipe 4 and discharge pipe 5 are communicated with each other on both sides thereof.

吸入管４及び吐出管５の内部にはモルトブレーン等の消
音材４１．５１や、消音用スプリング４２．５２等が備
えられており、これによって騒音を低減させである。Inside the suction pipe 4 and the discharge pipe 5, a sound deadening material 41, 51 such as maltbrane, a sound deadening spring 42, 52, etc. are provided, thereby reducing noise.

この種の送風機の空気圧縮原理は、一般に側溝原理と呼
ばれるもので、ケーシング２内で羽根車１を高速回転さ
せて、各羽根１０２−１０２間の空気を遠心力によって
羽根１０２の根元から先端方向に流出させ、ケーシング
ｚ内の空間６に環状の圧縮空気流（リングフロー）を形
成すると同時に１次の羽根１０２間に送り出すという、
圧縮、膨張作用の繰返しにより、吸入管４から吸入され
た空気を圧縮し、吐出管５から排出するものである。The air compression principle of this type of blower is generally called the gutter principle, in which the impeller 1 is rotated at high speed within the casing 2, and the air between the blades 102-102 is compressed by centrifugal force in the direction from the root of the blade 102 to the tip. to form a ring-shaped compressed air flow (ring flow) in the space 6 in the casing z, and at the same time send it out between the primary blades 102.
By repeating compression and expansion, the air sucked in from the suction pipe 4 is compressed and is discharged from the discharge pipe 5.

羽根車１の側面とケース部材２１及びケース蓋部材２２
の内壁面とは、平面部１０３　、１０４と平面部２１２
　、２２２とを僅かのクリアランスｄ１を隔てて対面さ
せであるから、環状の空間６で圧縮された空気が、ケー
シング２の内部において、外周部から内径側に漏洩する
ことがない。The side surface of the impeller 1, the case member 21, and the case lid member 22
The inner wall surfaces of the plane portions 103 and 104 and the plane portion 212
, 222 face each other with a slight clearance d1 therebetween, so that the air compressed in the annular space 6 does not leak from the outer circumference toward the inner diameter inside the casing 2.

発明が解決しようとする問題点 上述のように、この種の送Ｘａは羽根車ｌをケーシング
２内で高速回転させることと、各羽根１０２　間にリン
グフローを発生させて、羽根１０２の数に応じた段数で
、多段的かつ連続的に空気圧縮、送出を行なうものであ
ることから、高周波騒音、特に、耳障りな１０００〜４
０００Ｈｚ付近の騒音の発生は宿命的な問題であった。Problems to be Solved by the Invention As mentioned above, this type of feeding Xa involves rotating the impeller l at high speed within the casing 2, generating a ring flow between each blade 102, and increasing the number of blades 102. Since air is compressed and delivered in a multi-stage and continuous manner with the corresponding number of stages, high-frequency noise, especially the harsh 1000~4
The generation of noise around 000Hz was a fatal problem.

高周波騒音低減のための従来技術として、例えば実公昭
５３−２１７６２号公報や、実公昭５９−４１３５９号
公報に開示されたものが公知である。しかしながら、こ
れらの従来技術では、送風機の構造を特殊なものとしな
ければならず、実用性に欠ける。Conventional techniques for reducing high frequency noise are known, for example, as disclosed in Japanese Utility Model Publication No. 53-21762 and Japanese Utility Model Publication No. 59-41359. However, these conventional techniques require a special blower structure and lack practicality.

しかも、前述したような送風機の用途拡大に伴ない、従
来とは異なった状態での高周波騒音の発生が新たに発生
しており、その解決が急がれている。即ち、紙板の浮上
げ（ホバークラフト式）、低圧シリンダの駆動、フィル
ム吸着、真空ロボットハンド或いは真空エアチャック等
に使用した場合には、送風機の吐出管または吸入管が締
切状態となり、送風機に対する負荷が極めて大きくなる
。このため、従来の一般的な用途では高周波騒音発生の
問題を生じない場合でも、極めて大きな高周波騒音が発
生してしまうという新たな問題を生じている。Moreover, with the expansion of the uses of blowers as described above, high-frequency noise is newly occurring under conditions different from those in the past, and a solution to this problem is urgently needed. In other words, when used for lifting paper boards (hovercraft type), driving low-pressure cylinders, adsorbing films, vacuum robot hands, vacuum air chucks, etc., the discharge pipe or suction pipe of the blower becomes closed and the load on the blower is reduced. becomes extremely large. For this reason, even if the problem of high frequency noise generation does not occur in conventional general applications, a new problem has arisen in that extremely large high frequency noise is generated.

更に、この種の送風機は、電動機３側に固着されたケー
ス部材２１に対して、ケース蓋部材２２を組合わせる構
造であるため、ケース蓋部材２２が空気の圧縮、膨張に
つれて高周波振動し、それが高周波騒音の発生源となる
という構造上の問題もある。即ち、ケーシング部材２１
は電動４！１３に固定されていて高周波振動が抑制され
るが、ケース蓋部材２２は肉厚を薄くして軽量化するの
が普通であるため、高周波振動を起こし易い。ケース蓋
部材２２の肉厚を厚くすると、高周波騒音は抑制できる
が、この抑制効果を得るためにはケース蓋部材２２の厚
みを非常に厚くしなければならず、重くて持運びが困難
になると共に、コスト高を招き、実用的でない。Furthermore, since this type of blower has a structure in which a case cover member 22 is combined with a case member 21 fixed to the electric motor 3 side, the case cover member 22 vibrates at high frequencies as the air compresses and expands. There is also a structural problem in that it becomes a source of high-frequency noise. That is, the casing member 21
is fixed to the electric motor 4!13 and high frequency vibrations are suppressed, but since the case lid member 22 is usually made thinner and lighter, it is more likely to generate high frequency vibrations. High-frequency noise can be suppressed by increasing the thickness of the case cover member 22, but in order to obtain this suppressing effect, the case cover member 22 must be extremely thick, making it heavy and difficult to carry. At the same time, this increases the cost and is not practical.

問題点を解決するための手段 上述する従来の問題点を解決するため、本発明は、外周
に多数の羽根を設けた羽根車と、この羽根車を回転可能
に覆うケーシングと、前記羽根車を回転駆動する電動機
とを備え、前記羽根車の両側面の少なくとも一側面に平
面部を設け、前記羽根車の前記平面部と対面する前記ケ
ーシング内壁面に平面部を設けた送風機において、前記
羽根車の前記平面部または前記ケーシングの前記平面部
の少なくとも一方に、前記羽根車の回転方向に沿う弧状
の凹溝を設けたことを特徴とする。Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention provides an impeller having a large number of blades on its outer periphery, a casing that rotatably covers the impeller, and a casing that rotatably covers the impeller. In the blower, the blower includes a rotationally driven electric motor, a flat part is provided on at least one of both sides of the impeller, and a flat part is provided on the inner wall surface of the casing facing the flat part of the impeller. An arcuate groove extending along the rotational direction of the impeller is provided in at least one of the flat part of the casing and the flat part of the casing.

作用 上述のように、側溝原理による送風機において１羽根車
の側面またはこれを収納するケーシングの内壁面の少な
くとも一方に１回転方向に沿う弧状の凹溝を設けると、
ケーシングを通して出る耳障りな１０００〜４０００Ｈ
ｚ付近の金属音の騒音が低減することが解った。これは
、凹溝による高周波干渉作用、見掛は上のヤング率の変
化等が複雑に絡み合って、高周波振動が抑制されるため
と推測される。Function As mentioned above, in a blower based on the gutter principle, if an arcuate concave groove along the direction of one rotation is provided on at least one side of one impeller or the inner wall surface of the casing that houses the impeller,
Harsh 1000~4000H coming out through the casing
It was found that the noise of metallic sounds near z was reduced. This is presumed to be because the high-frequency interference effect of the grooves, the apparent change in Young's modulus, etc. are intricately intertwined, and the high-frequency vibrations are suppressed.

また、凹溝を回転方向に沿う弧状にすることにより、羽
根車の側面側の平面部と、ケーシングの内壁面の平面部
との間に、所定のクリアランスが保たれ、圧縮空気が外
周部から内径側を通って漏洩するのが阻止でき、圧力の
低下を招くこともない。In addition, by making the concave groove arc-shaped along the rotation direction, a predetermined clearance is maintained between the flat part on the side surface of the impeller and the flat part on the inner wall surface of the casing, allowing compressed air to flow from the outer periphery. Leakage through the inner diameter side can be prevented and no pressure drop will occur.

更に、羽根車の平面部またはケーシングの平面部の少な
くとも一方に、羽根車の回転方向に沿う弧状の凹溝を設
けるだけでよいので１重量が増大したり、コスト高にな
ることもなく、実用性に富んだものとなる。Furthermore, since it is only necessary to provide an arcuate groove along the rotational direction of the impeller on at least one of the plane part of the impeller or the plane part of the casing, there is no increase in weight or cost, making it practical. It becomes sexual.

実施例 第１図は本発明に係る送風機の要部の拡大部分欠損図で
ある０図において、第５図〜第７図と同一の参照符号は
同一性ある構成部分を示している。この実施例では、ケ
ース蓋部材２２の内壁面に形成された平面部２２２に凹
溝７を設けである。Embodiment FIG. 1 is an enlarged partially cutaway view of essential parts of a blower according to the present invention, and the same reference numerals as in FIGS. 5 to 7 indicate the same components. In this embodiment, a groove 7 is provided in a flat surface 222 formed on the inner wall surface of the case lid member 22.

凹溝７は、第２図に示すように、羽根車ｌの回転軸に一
致する中心０１に関して同心状に、間隔をおいて、リン
グ状に複数個形成するのが望ましい。凹溝７は、この実
施例では、ケース蓋部材２２に形成しであるが、羽根車
ｌの平面部１０４に形成しても良く、或いはケース蓋部
材２２と合せて、ケース部材２１の平面部２１２に形成
してもよい。また、隣合う凹溝７−７間に両者を連通さ
せる凹溝を設けてもよい、更に凹溝７は無端状ではなく
、途中で区切ってもよい、凹溝７の寸法は、送風機の大
きさや、ケーシング２の肉厚等の違いによって変化する
が、電動機３として、Ａ　Ｃ２００■、７５０Ｗ程度の
ものを用いる通常のタイプのものでは、＠１０ｍｍ、深
さ３鳳鳳程度である。As shown in FIG. 2, it is preferable that a plurality of grooves 7 are formed in a ring shape concentrically with respect to a center 01 that coincides with the rotation axis of the impeller 1 at intervals. Although the groove 7 is formed in the case lid member 22 in this embodiment, it may be formed in the flat part 104 of the impeller l, or it can be formed in the flat part of the case member 21 together with the case lid member 22. 212 may be formed. Further, a groove may be provided between adjacent grooves 7 to 7 to communicate with each other.Furthermore, the groove 7 may not be endless but may be separated in the middle.The dimensions of the groove 7 may be determined by the size of the blower. Although it varies depending on the wall thickness of the sheath and casing 2, a normal type electric motor 3 using an AC 200cm, 750W or so has a width of 10 mm and a depth of about 3 mm.

このような凹溝７があると、ケーシング２の前方に出る
高周波騒音、特に、耳障りな２５００Ｈｚ周辺の金属騒
音を低減できる。With such a groove 7, it is possible to reduce high frequency noise emitted from the front of the casing 2, especially the harsh metallic noise around 2500 Hz.

しかも、凹溝７は平面部に対し、羽根車の回転方向に沿
って、同心状等に形成しであるから、羽根車１の側面側
の平面部１０４と、ケーシング２の内壁面の平面部２２
２との間に、所定のクリアランスｄ１が保たれ、圧縮空
気が外周部から内径側を通って漏洩するのが用土でき、
圧力の低下を招くこともない。Moreover, since the groove 7 is formed concentrically with respect to the plane part along the rotational direction of the impeller, the groove 7 is formed concentrically with respect to the plane part 104 on the side surface of the impeller 1 and the plane part of the inner wall surface of the casing 2. 22
2, a predetermined clearance d1 is maintained, and the compressed air leaks from the outer circumference through the inner diameter side.
It also does not cause a drop in pressure.

次に実測データを挙げて本発明の効果を具体的に説明す
る。第３図及び第４図は送風機の周波数−音圧レベル特
性の実測データを示す図であり、曲線Ａ、、Ａ２は本発
明に係る送風機の特性、Ｂｌ　、Ｂ２は従来の送風機の
特性を示す、第３図は吸入管を締切った場合の実測デー
タで、フィルム吸着、真空ロボットハンド或いは真空エ
アチャック等に用いた場合に対応する。第４図は吐出管
を締切った場合の実測データで、紙板の浮上げ、低圧シ
リンダの駆動等の用途に対応する。Next, the effects of the present invention will be specifically explained using actual measurement data. 3 and 4 are diagrams showing actual measurement data of the frequency-sound pressure level characteristics of the blower, where curves A, A2 show the characteristics of the blower according to the present invention, and curves B1 and B2 show the characteristics of the conventional blower. , FIG. 3 shows actual measurement data when the suction pipe is closed, and corresponds to the case where it is used for film suction, a vacuum robot hand, a vacuum air chuck, etc. Figure 4 shows actual measurement data when the discharge pipe is closed, and corresponds to applications such as lifting paper boards and driving low-pressure cylinders.

上記の実測データを得るに当っては、電動機３としてＡ
Ｃ２００Ｖ、７５０Ｗの誘導電動機を使用し、これに同
一の構造の送風部分（ケーシング。In obtaining the above measured data, A is used as the motor 3.
A C200V, 750W induction motor is used, and a ventilation part (casing) with the same structure is used.

羽根車等）を結合して送風機を構成した。ただし、従来
のものは凹溝７を持たない。impellers, etc.) to form a blower. However, the conventional one does not have the groove 7.

まず、第３図を見ると、本発明に係る送風機は、従来の
ものに比較して、２０００Ｈｚ〜４０００Ｈｚの付近に
おける゛騒音レベルが著しく低減している。特に、耳障
りな金属音となる２０００Ｈｚ〜３０００Ｈｚ付近で、
騒音レベルの改善効果が著しく、２５００Ｈｚでは従来
の７６ｄＢから５９ｄＢへと、１７ｄＢも低下している
。First, looking at FIG. 3, compared to the conventional blower, the noise level in the vicinity of 2000 Hz to 4000 Hz is significantly reduced in the blower according to the present invention. Especially around 2000Hz to 3000Hz, which produces a harsh metallic sound.
The effect of improving the noise level is remarkable, with a reduction of 17 dB from the conventional 76 dB to 59 dB at 2500 Hz.

第４図においても同様の傾向が見られ、２５００Ｈｚで
は従来の７０ｄＢから６３ｄＢへと、７ｄＢ程度低下し
ている。A similar trend is seen in FIG. 4, with a decrease of about 7 dB from the conventional 70 dB to 63 dB at 2500 Hz.

なお、上記実施例では両羽根型のものを例にとって説明
したが１片羽根型のものであっても、同様の効果が得ら
れる。In the above embodiment, a double-blade type was used as an example, but the same effect can be obtained even if a single-blade type is used.

発明の効果 以上述べたように１本発明によれば１羽根車の側面また
はこれを収納するケーシングの内壁面の少なくとも一方
に、回転方向に沿う凹溝を設けることにより、吸入管或
いは吐出管の締切動作等に対して、圧力の低下等を招く
ことなく、耳障りな金属音領域の騒音を、簡単かつ確実
に低減させ得る実用化の容易な送風機を提供することが
できる。Effects of the Invention As described above, according to the present invention, a concave groove along the rotational direction is provided on at least one of the side surface of the impeller or the inner wall surface of the casing housing the impeller, so that the suction pipe or the discharge pipe can be It is possible to provide a blower that is easy to put into practical use and can easily and reliably reduce noise in the harsh metallic sound region during a shutoff operation or the like without causing a drop in pressure or the like.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明に係る送風機の要部の部分欠損拡大図、
第２図はケーシングを構成するケース蓋部材を内面側か
ら見た図、第３図は送風機の吸入管を締切った場合の周
波数−音圧レベルの実測データをグラフ化して示す図、
第４図は同じく吐出管を締切った場合の周波数−音圧レ
ベルの実測データをグラフ化して示す図、第５図は従来
の送風機の部分欠損正面図、第６図は同じくその側面図
、第７図は従来の送風機の要部拡大部分断面図、第８図
は同じくケーシングの内面図である。 ｌ−Φ・羽根車　　　　１０２　・・・羽根２・・・ケ
ーシング　　２１・Φ・ケース部材２２・拳・ケース蓋
部材　　３・・・電動機１０３　、１０４　・Φ拳平面
部 ２１２　、２２２　・・拳平面部 ７・・・凹溝 第１図 第２図 第３図 Ｘ７フーブシ（ンＦｆｌＣ，帽摩り文Ｈ。 第４図 オククーフ゛バ°′ンＦ”７’Ｊｕｉｌ、１款Ｈ２第６
図 ９　　　　　　　　　コ 第７図FIG. 1 is an enlarged view of the main parts of the blower according to the present invention, with partial defects;
Fig. 2 is a view of the case lid member constituting the casing viewed from the inner side, Fig. 3 is a graph showing the measured data of frequency vs. sound pressure level when the suction pipe of the blower is closed.
Fig. 4 is a graph showing the measured frequency-sound pressure level data when the discharge pipe is closed, Fig. 5 is a front view of a conventional blower with a partially damaged part, and Fig. 6 is a side view thereof. FIG. 7 is an enlarged partial sectional view of the main part of a conventional blower, and FIG. 8 is an inner view of the casing. l-Φ・Impeller 102...Blade 2...Casing 21・Φ・Case member 22・Fist・Case lid member 3...Electric motor 103, 104・ΦFist plane part 212, 222...Fist plane part 7... Concave groove Fig. 1 Fig. 2 Fig. 3
Figure 9 Figure 7

Claims (9)

【特許請求の範囲】[Claims] （１）外周に多数の羽根を設けた羽根車と、この羽根車
を回転可能に覆うケーシングと、前記羽根車を回転駆動
する電動機とを備え、前記羽根車の両側面の少なくとも
一側面に平面部を設け、前記羽根車の前記平面部と対面
する前記ケーシング内壁面に平面部を設けた送風機にお
いて、前記羽根車の前記平面部または前記ケーシングの
前記平面部の少なくとも一方に、前記羽根車の回転方向
に沿う凹溝を設けたことを特徴とする送風機。(1) An impeller having a large number of blades on its outer periphery, a casing that rotatably covers the impeller, and an electric motor that rotationally drives the impeller, and at least one of both sides of the impeller has a flat surface. and a flat part is provided on the inner wall surface of the casing that faces the flat part of the impeller, at least one of the flat part of the impeller or the flat part of the casing has a A blower characterized by having a concave groove along the direction of rotation. （２）前記ケーシングは、前記電動機側に固着されるケ
ース部材と、このケース部材の前面に結合されるケース
蓋部材とでなることを特徴とする特許請求の範囲第１項
に記載の送風機。(2) The blower according to claim 1, wherein the casing includes a case member fixed to the electric motor side and a case lid member coupled to the front surface of the case member. （３）前記凹溝は、前記ケース蓋部材の前記平面部に形
成したことを特徴とする特許請求の範囲第２項に記載の
送風機。(3) The blower according to claim 2, wherein the groove is formed in the flat part of the case lid member. （４）前記凹溝は、前記ケース部材の平面部に形成した
ことを特徴とする特許請求の範囲第２項または第３項に
記載の送風機。(4) The blower according to claim 2 or 3, wherein the groove is formed on a flat surface of the case member. （５）前記凹溝は、前記羽根車の前記平面部に形成した
ことを特徴とする特許請求の範囲第１項、第２項、第３
項または第４項に記載の送風機。(5) Claims 1, 2, and 3, characterized in that the groove is formed in the flat part of the impeller.
The blower according to paragraph or paragraph 4. （６）前記凹溝は、回転径方向に間隔をおいて複数個形
成したことを特徴とする特許請求の範囲第１項、第２項
、第３項、第４項または第５項に記載の送風機。(6) A plurality of the grooves are formed at intervals in the rotational radial direction, as set forth in claim 1, 2, 3, 4, or 5. blower. （７）前記凹溝は、互いに独立して形成したことを特徴
とする特許請求の範囲第６項に記載の送風機。(7) The blower according to claim 6, wherein the grooves are formed independently of each other. （８）前記凹溝の隣接する凹溝は、互いに連通させたこ
とを特徴とする特許請求の範囲第６項に記載の送風機。(8) The blower according to claim 6, wherein adjacent grooves of the grooves are communicated with each other. （９）前記凹溝は、回転軸心に関して同心状に形成した
ことを特徴とする特許請求の範囲第１項　第２項、第３
項、第４項、第５項、第６項、第７項または第８項に記
載の送風機。(9) The groove is formed concentrically with respect to the axis of rotation.Claims 1, 2 and 3
The blower according to item 4, item 5, item 6, item 7, or item 8.