JP4951571B2

JP4951571B2 - Screw compressor

Info

Publication number: JP4951571B2
Application number: JP2008089180A
Authority: JP
Inventors: 裕敬亀谷; 紘太郎千葉; 英晴田中; 正彦高野
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2008-03-31
Filing date: 2008-03-31
Publication date: 2012-06-13
Anticipated expiration: 2028-03-31
Also published as: JP2009243325A

Description

本発明は空気や冷媒ガスなどの気体を圧縮するに代表されるスクリュー圧縮機に関わり、高性能で低騒音に好適な歯形を有するロータを備えたスクリュー圧縮機に関する。 The present invention relates to a screw compressor represented by compressing a gas such as air or refrigerant gas, and more particularly to a screw compressor including a rotor having a tooth profile suitable for high performance and low noise.

スクリュー圧縮機は空気圧源としての空気圧縮機や、比較的大規模な冷凍空調サイクル用冷媒圧縮機として広く活用されている。これらスクリュー圧縮機の心臓部といえるスクリューロータの幾何形状は性能や振動騒音、信頼性に大きく影響する。特にロータの軸直角断面における輪郭形状として定義される歯形は、重要な特性決定因子であり、古くからさまざまな研究がなされ各種の歯形が提案されてきた。 Screw compressors are widely used as air compressors as air pressure sources and refrigerant compressors for relatively large-scale refrigeration and air conditioning cycles. The geometry of the screw rotor, which is the heart of these screw compressors, greatly affects performance, vibration noise, and reliability. In particular, the tooth profile defined as the contour shape in the cross section perpendicular to the axis of the rotor is an important characteristic determining factor, and various studies have been made since a long time.

例えば、特公昭６３−４３５９７号公報（特許文献１）には、雌ロータの前進面に放物線を採用し加工する際の刃具の摩滅を考慮した歯形が示されている。また、特開２００１−２２７４８５号公報（特許文献２）には、かみ合い線を短くすることで、作動ガス（内部に閉じ込められて圧縮される過程にある気体）の漏洩を少なくし、性能を向上する歯形が示されている。 For example, Japanese Examined Patent Publication No. 63-43597 (Patent Document 1) shows a tooth profile that takes into account wear of a blade when a parabola is employed on the advance surface of a female rotor for machining. Japanese Patent Laid-Open No. 2001-227485 (Patent Document 2) reduces the leakage of the working gas (the gas in the process of being confined inside and compressed) by shortening the meshing line, thereby improving the performance. The tooth profile to be shown is shown.

特公昭６３−４３５９７号公報Japanese Examined Patent Publication No. 63-43597 特開２００１−２２７４８５号公報JP 2001-227485 A

スクリュー圧縮機においては、高性能化と低騒音化が永続的な研究課題となっている。そして、スクリュー圧縮機の心臓部であるロータの歯形は性能と騒音を決定する重要な要因であるために、これまでさまざまな歯形が研究され多くの発明がなされてきた。 In screw compressors, high performance and low noise are permanent research topics. Since the tooth profile of the rotor, which is the heart of the screw compressor, is an important factor that determines performance and noise, various tooth profiles have been studied and many inventions have been made.

特許文献１及び２による歯形に対しては、更なる性能向上や振動騒音の低減が要求されるようになってきた。また、圧縮機の運転条件や容量制御範囲を拡大したいとの要求から、吸入圧力と吐出圧力の稼動範囲を拡大し、広い圧力条件においても安定して回転することが要求されるようになった。 For the tooth profile according to Patent Documents 1 and 2, further performance improvement and reduction of vibration noise have been demanded. In addition, due to the demand to expand the operating conditions and capacity control range of the compressor, the operating range of suction pressure and discharge pressure has been expanded, and it has been required to rotate stably even under wide pressure conditions. .

スクリュー圧縮機における特有の現象に歯面分離振動があり、歯形の持つ特性に吸入圧力と吐出圧力の条件が揃うと発生することがある。通常の運転条件では、発生しないものの、容量制御中や移行過程で発生することもある。歯面分離振動は発生しないにこしたことはないが、発生しても振動騒音が大きくなく、歯面が損傷しなければ致命的な欠陥ではない。 Tooth surface separation vibration is a unique phenomenon in screw compressors, and may occur when the conditions of suction pressure and discharge pressure are matched to the characteristics of the tooth profile. Although it does not occur under normal operating conditions, it may occur during capacity control or during the transition process. Tooth separation vibration is never generated, but even if it occurs, vibration noise is not large, and it is not a fatal defect unless the tooth surface is damaged.

スクリュー圧縮機の性能を低下させる原因には内部漏洩と、吸入抵抗などがあげられる。 Causes that degrade the performance of the screw compressor include internal leakage and suction resistance.

吸入抵抗による性能低下とは、スクリュー圧縮機のロータの歯溝が形成する作動室に被圧縮気体が吸い込まれる過程での流体抵抗が大きいことを意味し、吸入圧損とも呼ばれる。歯溝までの吸入流路は設計上十分な断面積を確保し滑らかな形状で抵抗が小さくなるよう配慮されていても、実動時に高圧となった作動室からロータ間などの隙間を通って被圧縮流体や油が噴出し、吸入の流れを阻害し抵抗が増すことがある。 The performance deterioration due to the suction resistance means that the fluid resistance is large in the process of sucking the compressed gas into the working chamber formed by the tooth space of the rotor of the screw compressor, and is also called suction pressure loss. Even if the suction flow path to the tooth gap is designed to ensure a sufficient cross-sectional area and have a smooth shape to reduce resistance, it passes through the gap between the rotor and the working chamber where the pressure is high during actual operation. Compressed fluid or oil may spout, impeding the suction flow and increasing resistance.

なお、ロータが滑らかに回転できるようにロータ間には微小な隙間を設けている。この隙間を通って高圧となった作動室から反対側にある低圧の作動室への被圧縮気体の噴出は歯形加工や熱変形補償の精度向上により低減することはできるが、皆無とすることはできない。また、油冷式スクリュー圧縮機においては、作動室に油を注入するので、高圧の被圧縮気体とともに油も噴出することになる。高圧の被圧縮気体は圧縮により温度が上昇し、その気体から受熱した油も通常は吸入したばかりの被圧縮気体よりも高温となっている。 A minute gap is provided between the rotors so that the rotors can rotate smoothly. The jet of compressed gas from the high pressure working chamber through this gap to the low pressure working chamber on the opposite side can be reduced by improving the accuracy of tooth profile processing and thermal deformation compensation, Can not. In the oil-cooled screw compressor, oil is injected into the working chamber, so that the oil is also ejected together with the high-pressure compressed gas. The pressure of the high-pressure compressed gas rises due to compression, and the oil received from the gas is usually at a higher temperature than the compressed gas that has just been sucked.

上記２つの特許文献の歯形において軸方向の断面を見てみると、いずれも高圧流体が斜め上方に吹き出し、その方向と被圧縮気体が流入してくる方向がほぼ同じである。したがって、噴出してくる流体に阻害されて、吸い込み抵抗が増すとともに、高温の噴出流体との熱交換により被圧縮気体の温度が上がり、体積膨張によって質量流量が低下してしまう懸念があった。 Looking at the axial cross sections of the tooth profiles of the above two patent documents, the high pressure fluid blows obliquely upward and the direction in which the compressed gas flows in is almost the same. Accordingly, there is a concern that the suction resistance is increased by the fluid ejected, the suction resistance is increased, the temperature of the compressed gas is increased by heat exchange with the high-temperature ejected fluid, and the mass flow rate is decreased due to volume expansion.

内部漏洩は圧縮過程や圧縮完了した高圧の被圧縮気体がロータ間などの隙間を通って、吸入過程や圧縮途上にある作動室に逆流してしまう現象である。逆流する流路の隙間としてブローホールやシール線がよく知られ、その面積を縮小するための歯形も多く発明されてきた。しかし、吐出端面に周期的に現れる吸入側への直通路については十分な解決策が示されていなかった。 Internal leakage is a phenomenon in which a compressed high-pressure compressed gas that has been compressed or compressed passes back through a gap such as between the rotors and into a working chamber that is in the process of suction or compression. Blow holes and seal lines are well known as gaps in the flow path of backflow, and many tooth forms for reducing the area have been invented. However, no sufficient solution has been shown for the direct passage to the suction side that periodically appears on the discharge end face.

上記状況に鑑み、本発明のスクリュー圧縮機は、歯面分離振動が発生しても振動騒音が拡大しにくく、広い圧力範囲で安定して運転できることを第１の目的とする。また、内部漏洩と吸入抵抗を低減することによる高効率化を実現することを第２の目的とする。 In view of the above situation, it is a first object of the screw compressor of the present invention that vibration noise is difficult to expand even if tooth surface separation vibration occurs, and can be stably operated in a wide pressure range. A second object is to achieve high efficiency by reducing internal leakage and suction resistance.

上記課題を解決するために本発明のスクリュー圧縮機は、両ロータの軸直角断面である軸に垂直な断面上における輪郭形状を表す歯形曲線のうち、雄ロータのピッチ円より外側であって雌ロータのピッチ円半径より内側に相当する互いに噛み合う範囲が、前進面ならびに後進面上の両面をインボリュート曲線とする。インボリュート曲線とした区間の長さは前進面と後進面で異なってもかまわない。また、前進面と後進面のインボリュート曲線の圧力角が異なっていてもよい。 In order to solve the above-mentioned problems, the screw compressor of the present invention is a female tooth profile curve representing a contour shape on a cross section perpendicular to the axis which is a cross section perpendicular to the axis of both rotors, and is located outside the pitch circle of the male rotor. The intermeshing range corresponding to the inside of the pitch circle radius of the rotor is an involute curve on both the forward and reverse surfaces. The length of the section formed as an involute curve may be different between the forward surface and the reverse surface. Further, the pressure angle of the involute curve on the forward surface and the reverse surface may be different.

また、上記課題をよりよく解決するために、本発明のスクリュー圧縮機は、両ロータの軸直角断面である軸に垂直な断面上における輪郭形状を表す歯形曲線のうち、雄ロータのピッチ円より外側であって雌ロータのピッチ円半径より内側に相当する互いに噛み合う範囲が、前進面ならびに後進面上の両面をインボリュート曲線とし、雌ロータの歯底点から前進面側が、最初の区間がピッチ点を中心とする円弧、滑らかに続く次の区間が前記両ロータの軸を含む平面に平行な面上の曲線からなり、前記雄ロータの歯先点から後進面側が、最初の区間が前記ピッチ点を中心とする円弧の半径よりも小さい半径の第１の円弧で、次の区間が第一の円弧に滑らかに連続し、かつ曲がり方向が同じ第２の円弧で、当該第２の円弧の中心は雄ピッチ円上に位置する歯形を有するものである。 In order to better solve the above problem, the screw compressor of the present invention is based on the pitch circle of the male rotor among the tooth profile curves representing the contour shape on the cross section perpendicular to the axis which is the cross section perpendicular to the axis of both rotors. The outer meshing range corresponding to the inside of the pitch circle radius of the female rotor is an involute curve on both the advancing surface and the reversing surface. The next section that continues smoothly is a curve on a plane parallel to the plane including the axes of the two rotors, and the reverse section side from the tooth tip point of the male rotor is the first section is the pitch point. A first arc having a radius smaller than the radius of the arc centered on the second arc, a second arc smoothly following the first arc and having the same bending direction, and the center of the second arc on the male pitch circle And has a tooth profile that location.

本発明のスクリュー圧縮機によれば、広い圧力範囲で安定し、高効率化を実現することができる。 According to the screw compressor of the present invention, it is stable in a wide pressure range, and high efficiency can be realized.

本発明の一実施例を図１〜図３を用いて説明する。図１は雌雄ロータの歯形の拡大図、図２は圧縮機の断面図である。 An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an enlarged view of the tooth profile of a male and female rotor, and FIG. 2 is a cross-sectional view of the compressor.

スクリュー圧縮機はケーシング３の中に一部を重複した２つの円筒穴からなるボア４を有し、各々の円筒穴の中で回転する雄ロータ１と雌ロータ２は噛み合いながら回転する。雄ロータ１と雌ロータ２の噛み合い部分は理論的には隙間０となるよう幾何学的に歯形が設計され、それに熱変形やガス圧変形、振動や加工誤差を許容できるように隙間を設定し、その分だけ歯面を減肉し製作している。本発明の本質は隙間の設定方法には直接関与しないので、隙間の存在は考察に加えるものの本実施例において説明する歯形は幾何設計上の歯形について述べる。したがって、文中で「接触」と表現しても実際の歯形間には微小な隙間が存在する場合が多い。 The screw compressor has a bore 4 composed of two cylindrical holes partially overlapping in the casing 3, and the male rotor 1 and the female rotor 2 rotating in the respective cylindrical holes rotate while meshing with each other. The meshing part of the meshing portion of the male rotor 1 and the female rotor 2 is theoretically designed so that the gap is zero, and the gap is set so as to allow thermal deformation, gas pressure deformation, vibration and machining errors. The tooth surface is thinned by that much. Since the essence of the present invention is not directly related to the setting method of the gap, the existence of the gap is added to the consideration, but the tooth profile described in the present embodiment will be described as a geometrical tooth profile. Therefore, even if it is expressed as “contact” in the sentence, there are often small gaps between actual tooth forms.

図１には、雄ロータ１の歯形と雌ロータ２の歯形を１歯分だけ示す。雄ロータは時計回り、雌ロータ２は反時計回りする。この図では雄ロータの歯先点１１が雌ロータ２の歯底点２１と接しており、このときの両ロータの回転角度を基準すなわち回転角度０度とする。これらの点１１，２１から回転方向を前進面、反回転方向を後進面と呼ぶ。雄ロータの回転中心と雌ロータの回転中心を結ぶ線分を雄ロータの歯数と雌ロータの歯数の比で内分した点をピッチ点Ｐといい、実体は無いものの設計上は重要な位置である。雄の中心からピッチ点Ｐまでの距離を雄ピッチ円半径、雌の中心からピッチ点までの距離を雌ピッチ円半径という。また、雄ロータ１の歯形を雄歯形、雌ロータ２の歯形を雌歯形と称する。 In FIG. 1, the tooth profile of the male rotor 1 and the tooth profile of the female rotor 2 are shown for one tooth. The male rotor rotates clockwise and the female rotor 2 rotates counterclockwise. In this figure, the tip point 11 of the male rotor is in contact with the root point 21 of the female rotor 2, and the rotation angle of both rotors at this time is the reference, that is, the rotation angle is 0 degree. From these points 11 and 21, the rotation direction is referred to as a forward surface and the counter-rotation direction is referred to as a reverse surface. The point where the line segment connecting the rotation center of the male rotor and the rotation center of the female rotor is internally divided by the ratio of the number of teeth of the male rotor to the number of teeth of the female rotor is called the pitch point P. Position. The distance from the center of the male to the pitch point P is called the male pitch circle radius, and the distance from the center of the female to the pitch point is called the female pitch circle radius. The tooth profile of the male rotor 1 is referred to as a male tooth profile, and the tooth profile of the female rotor 2 is referred to as a female tooth profile.

前進面における歯形曲線について説明する。 The tooth profile curve on the advancing surface will be described.

雌歯形において、歯底点２１から前進面側に点２２までの区間はピッチ点Ｐを中心とする円弧とする。ピッチ点Ｐ中心の円弧は、機構学で知られる「噛み合いの条件」から全域で同時に接触する。したがって、この区間で噛み合う雄歯形上の区間１１から１２も同じ円弧となる。 In the female tooth profile, the section from the root point 21 to the point 22 on the forward surface side is an arc centered on the pitch point P. The arc at the center of the pitch point P is in contact with the entire area simultaneously from the “meshing condition” known in mechanics. Therefore, the sections 11 to 12 on the male teeth meshing in this section also have the same arc.

雌歯形上の点２２から点２３の区間は「水平接触線を形成する曲線」である。本実施例では、各ロータを図１や図２の置き方をした場合に紙面上で横線となる方向を水平、縦線となる方向を鉛直として説明する。圧縮機全体の設置方向を変えた場合には、真の水平や鉛直と異なる場合もある。 The section from point 22 to point 23 on the female tooth profile is a “curve that forms a horizontal contact line”. In the present embodiment, when the rotors are placed as shown in FIGS. 1 and 2, the horizontal direction is defined as horizontal and the vertical direction is defined as vertical. When the installation direction of the whole compressor is changed, it may be different from true horizontal or vertical.

「水平接触線」の意味を説明する。この区間２２，２３で相手となる雄ロータの区間１２，１３と接触するとき、その接触は一点でなされ、その位置が全て点１２，２２を通る同一の水平線上にくるようにする。接触点は、雄ロータ及び雌ロータの軸を含む面に平行な面上に常に存在する。すると雌歯形も雄歯形も区間１１，１２と同じ曲がり方向ながら、左端１２，２２側よりも右端１３，２３側の方が曲率が大きく（曲率半径が小さく）なる。 The meaning of “horizontal contact line” will be described. When the sections 22 and 23 come into contact with the mating male rotor sections 12 and 13, the contact is made at one point, and all the positions are on the same horizontal line passing through the points 12 and 22. The contact point is always present on a plane parallel to the plane containing the axes of the male and female rotors. Then, both the female tooth shape and the male tooth shape have the same bending direction as the sections 11 and 12, but the curvature on the right ends 13 and 23 side is larger (the curvature radius is smaller) than on the left ends 12 and 22 side.

雌雄とも歯形上の点１２や２２では点の両側の曲線が滑らかに連続し、これらの点では角にならない。 In both sexes, the curves on both sides of the point are smoothly continuous at the points 12 and 22 on the tooth profile and do not become corners at these points.

雄歯形の区間１３，１４と雌歯形の区間２３，２４は共にインボリュート曲線で互いに噛み合う。点１３ならびに点２３は歯形曲線を滑らかに接続する。雄歯形上の点１４の回転半径は雄ピッチ円半径よりも小さく、点１４はピッチ円の内側にある。同様に雌歯形上の点２４の回転半径は雌ピッチ円半径よりも大きく、点２４は雌ピッチ円の外側にある。これらインボリュート曲線どうしの接触点はピッチ点Ｐを通る直線上になる。 Both the male tooth sections 13 and 14 and the female tooth sections 23 and 24 mesh with each other by an involute curve. Points 13 and 23 connect the tooth profile curves smoothly. The radius of rotation of the point 14 on the male tooth shape is smaller than the male pitch circle radius, and the point 14 is inside the pitch circle. Similarly, the turning radius of the point 24 on the female tooth profile is larger than the female pitch circle radius, and the point 24 is outside the female pitch circle. The contact points between these involute curves are on a straight line passing through the pitch point P.

雄歯形の区間１４，１５は点１４でインボリュート曲線と滑らかに接続し、点１５で回転中心を中心とする歯底円弧に滑らかに接続する凹曲線である。同様に雌歯形の区間２４，２５は点２４でインボリュート曲線に滑らかに接続し、点２５で回転中心を中心とする外周円弧に滑らかに接続し、雄歯形の区間１４，１５と噛み合う滑らかな凸曲線である。 The male tooth sections 14 and 15 are concave curves that are smoothly connected to the involute curve at the point 14 and smoothly connected to the root arc around the center of rotation at the point 15. Similarly, the female tooth sections 24 and 25 are smoothly connected to the involute curve at the point 24, smoothly connected to the outer peripheral arc centered at the center of rotation at the point 25, and smoothly projecting with the male tooth sections 14 and 15. It is a curve.

次に後進面における歯形曲線について説明する。雄歯形の区間１１，１６は円弧でその半径は区間１１，１２の円弧の半径よりも小さく、その中心は歯先点１１とピッチ点Ｐを結ぶ線分上にある。したがって歯先点１１において前進面と後進面の２つの円弧は滑らかに接続する。その区間と噛み合う雌歯形の区間２１，２６は雄歯形の円弧によって創成された曲線となる。 Next, the tooth profile curve on the reverse surface will be described. The male tooth sections 11 and 16 are circular arcs, the radius of which is smaller than the radius of the circular arcs of the sections 11 and 12, and the center thereof is on the line segment connecting the tooth tip point 11 and the pitch point P. Therefore, at the tooth tip point 11, the two arcs of the forward surface and the reverse surface are smoothly connected. The female tooth sections 21 and 26 meshing with the section are curves created by the male tooth arc.

雌歯形の区間２６，２７は雌ピッチ円上に中心を有する円弧で、それと噛み合う雄歯形の区間１６，１７も雄ピッチ円上に中心を有する円弧である。ロータの回転により、それら中心がピッチ点Ｐに同時に重なるとき、２つの円弧１６，１７と２６，２７は重なって同時接触となる。図３における点１６と点２６において両側の曲線は滑らかに接続する。 The female-tooth shaped sections 26 and 27 are arcs having a center on the female pitch circle, and the male-tooth shaped sections 16 and 17 meshing therewith are also arcs having a center on the male pitch circle. When the center of the rotor overlaps with the pitch point P due to the rotation of the rotor, the two arcs 16, 17 and 26, 27 overlap and are in simultaneous contact. The curves on both sides are smoothly connected at points 16 and 26 in FIG.

雌歯形の区間２７，２８は半径が区間１１，１６の半径よりも小さい円弧で、その区間と噛み合う雄歯形の区間1７，1８は、区間２７，２８の円弧に創成された曲線である。点２７において両側の円弧は滑らかに接続し、噛み合う相手となる点１７も同様に両側の曲線が滑らかに接続する。 The female tooth sections 27 and 28 are arcs whose radius is smaller than the radius of the sections 11 and 16, and the male tooth sections 17 and 18 meshing with the sections are curves created in the arcs of the sections 27 and 28. The arcs on both sides are smoothly connected at the point 27, and the curves on both sides are also smoothly connected to the point 17 that is the mating partner.

雄歯形の区間１８，１９と、噛み合う相手となる雌歯形の区間２８，２９は共にインボリュート曲線で、区間１３，１４，２３，２４と同様の性質を有する。点１８，２８において両側の曲線は滑らかに接続する。点１９は雄ピッチ円の内側にあり、点２９は雌ピッチ円の外側にある。 The male tooth sections 18 and 19 and the female tooth sections 28 and 29 to be engaged with each other are both involute curves and have the same properties as the sections 13, 14, 23 and 24. At points 18 and 28, the curves on both sides are smoothly connected. Point 19 is inside the male pitch circle and point 29 is outside the female pitch circle.

雌歯形の区間２９，３０は中心が雌ピッチ円の内側にある円弧で、点２９はインボリュート曲線と滑らかに接続し、他端は雌外周円弧と滑らかに接続する。その区間と噛み合う雄歯形１９，２０は雌区間２９，３０に創成された曲線で点１９はインボリュート曲線と滑らかに接続し、点２０は雄歯底円弧と滑らかに接続する。 The female tooth sections 29 and 30 are arcs whose centers are inside the female pitch circle, the point 29 is smoothly connected to the involute curve, and the other end is smoothly connected to the female outer circumference arc. The male teeth 19 and 20 meshing with the section are curves created in the female sections 29 and 30, and the point 19 is smoothly connected to the involute curve, and the point 20 is smoothly connected to the male bottom arc.

１つの断面で見たとき、雄ロータ１と雌ロータ２を噛み合わせた時に接触する位置はロータの回転によって移動する。両ロータの歯がねじれていることから、立体的に見ると接触する位置は連続した線となり、それの形状を図４に示す。この線はシール線と呼ばれ、ロータの下側にある高圧となった作動室５と、吸入過程にある低圧の作動室６を隔てる区切りの線となる。シール線上の点も雌雄の歯形曲線に１対１で対応するので、雄歯形上の点１１〜２０に対応するように番号を付けると３１〜４０で示す位置となる。 When viewed in one cross section, the contact position when the male rotor 1 and the female rotor 2 are engaged with each other is moved by the rotation of the rotor. Since the teeth of both rotors are twisted, the contact position becomes a continuous line when viewed three-dimensionally, and the shape thereof is shown in FIG. This line is called a seal line and is a separating line separating the high-pressure working chamber 5 below the rotor and the low-pressure working chamber 6 in the suction process. Since the points on the seal line also correspond to the male and female tooth profile curves on a one-to-one basis, if numbers are assigned to correspond to the points 11 to 20 on the male tooth profile, the positions indicated by 31 to 40 are obtained.

円弧区間１１，１２によるシール線区間３１，３２は鉛直方向となり、ある軸直角断面では、この区間全域で同時に接触することがわかる。水平接触線区間２２，２３によるシール線区間３２，３３は水平な線分となる。なお、インボリュートによる区間では斜めの直線となる。 It can be seen that the seal line sections 31 and 32 formed by the arc sections 11 and 12 are in the vertical direction, and in a certain cross section perpendicular to the axis, they are simultaneously in contact with the entire section. The seal line sections 32 and 33 by the horizontal contact line sections 22 and 23 are horizontal line segments. In addition, in the section by involute, it becomes an oblique straight line.

本実施例の歯形の動作について説明する。ロータの回転によって、ねじれた歯の作用で作動室は吸入端７から吐出端８に向かって移動する。ロータの全長に及ぶ作動室６が最大容積となって、それより左側にある作動室は吸入過程で吸入流路４１と連通する。右側にある作動室は外周をボア３、端面をケーシングの端面でふさがれて閉じた室であるまま容積が縮小する。ある程度容積が縮小した作動室５はボアあるいは端面の少なくとも一方に開けられた穴である吐出ポートを経て吐出流路と連通する。吸入流路４１からボア内に吸い込まれた被圧縮気体は作動室６に閉じ込められ、圧縮された後に吐出流路４２から送り出されることになる。 The operation of the tooth profile of the present embodiment will be described. By rotation of the rotor, the working chamber moves from the suction end 7 toward the discharge end 8 by the action of twisted teeth. The working chamber 6 extending over the entire length of the rotor has a maximum volume, and the working chamber located on the left side of the working chamber 6 communicates with the suction flow path 41 during the suction process. The volume of the working chamber on the right side is reduced while the outer periphery is closed by the bore 3 and the end surface is closed by the end surface of the casing. The working chamber 5 whose volume has been reduced to some extent communicates with the discharge flow path via a discharge port which is a hole formed in at least one of the bore and the end face. The compressed gas sucked into the bore from the suction passage 41 is confined in the working chamber 6 and is sent out from the discharge passage 42 after being compressed.

油冷式の圧縮機においては、圧縮過程の前半の作動室に油が注入され、油はロータ間の接触駆動用の潤滑材，冷却媒体，隙間のシール材としての役割を担う。したがって、油は作動室の中で被圧縮気体と混在することになる。 In an oil-cooled compressor, oil is injected into the working chamber in the first half of the compression process, and the oil plays a role as a lubricant for driving the contact between the rotors, a cooling medium, and a sealant for the gap. Therefore, the oil is mixed with the compressed gas in the working chamber.

高圧の作動室５と低圧の作動室６は完全に区切られた空間ではなく、ロータ間の隙間などに代表されるいくつかの連通流路がある。もちろん性能の観点からはこれら連通流路は無い方が好ましいが、ロータの円滑な回転には欠かせないものである。ロータ間の連通流路はシール線を横断する部分が最も隙間が小さくなるので、ここを通り低圧側の作動室６に噴出する被圧縮気体や油はシール線に直交する方向に噴出することになる。 The high-pressure working chamber 5 and the low-pressure working chamber 6 are not completely separated spaces, but have some communication channels represented by gaps between the rotors. Of course, from the viewpoint of performance, it is preferable that there is no such communication channel, but it is indispensable for smooth rotation of the rotor. Since the communication passage between the rotors has the smallest gap in the portion that crosses the seal line, the compressed gas or oil that passes through the rotor to the low pressure side working chamber 6 is jetted in a direction perpendicular to the seal line. Become.

従来の歯形のシール線は図５に示す形状であり、前進面で形成される区間には左下から右上に斜めに延びる部分がある。この部分のシール線を横断して噴出する気体や油は吸入流路の方向を向いている。したがって、吸入してくる気体はこの逆方向の流れに逆らってボア内に流入せねばならず、圧力損失が大きかったし、圧縮によって高温となっている被圧縮気体や油と熱交換し吸気加熱よ呼ばれる損失要因となっていた。 The seal line of the conventional tooth profile has the shape shown in FIG. 5, and a section formed by the advancing surface has a portion extending obliquely from the lower left to the upper right. The gas or oil ejected across this portion of the seal line is directed toward the suction flow path. Therefore, the inhaled gas has to flow into the bore against this reverse flow, and the pressure loss is large, and heat is exchanged with the compressed gas and oil that are hot due to compression, and the intake air is heated. It was called a loss factor.

本実施例においては、シール線で吸入空間に面する上半分の主要部で形状が鉛直あるいは水平となる。区間３１，３２からの噴出は左方向で、区間３２，３３からの噴出は上方向となる。左方向は歯があるため噴出してもすぐに歯に衝突し、吸入流路への逆流とはならず、吸入の阻害要因とはならない。上方向はボア壁があるため、噴出してもすぐにボア内面に衝突し、やはり吸入流路への逆流とはならず、吸入の阻害要因とはならない。 In the present embodiment, the shape is vertical or horizontal in the upper half of the main portion facing the suction space by the seal line. The jets from the sections 31 and 32 are in the left direction, and the jets from the sections 32 and 33 are in the upward direction. Since there are teeth in the left direction, even if they are ejected, they immediately collide with the teeth and do not flow back into the suction flow path, and do not become a hindrance to suction. Since there is a bore wall in the upward direction, even if it is ejected, it immediately collides with the inner surface of the bore, so that it does not flow backward to the suction flow path, and does not become a hindrance to suction.

シール線の区間３６，３７は図３に示した雌雄歯形の後進面の円弧での接触を意味し、これが吐出端面においては吸入側への直通路が開く時の形状になる。吸入側への直通路は内部漏洩流路として好ましくない存在であるが、幾何学的にスクリュー圧縮機の歯形を形成する上で皆無とはしがたいものである。図１に示した歯形図では後進面に流路面積９として現れる。吐出端面に設ける吐出ポートの輪郭形状を工夫してこの流路が直接に吐出流路４２に面しないように設計しているが、十分なまでに塞ぐと、吐出流れの阻害要因ともなるので十分には塞ぎきれていない。 The sections 36 and 37 of the seal line mean contact in the arc of the reverse surface of the male and female teeth shown in FIG. 3, and this is the shape when the straight passage to the suction side is opened on the discharge end face. Although the direct passage to the suction side is not preferable as an internal leakage flow path, it is difficult to geometrically form the tooth profile of the screw compressor. In the tooth profile shown in FIG. 1, it appears as a flow path area 9 on the reverse surface. The outline of the discharge port provided on the discharge end face is devised so that this flow path does not directly face the discharge flow path 42. However, if it is blocked sufficiently, it becomes a hindrance to the discharge flow. It is not completely closed.

図５に示すように、従来の歯形ではこの直通路を通って吸入側に抜ける流れ４３の存在する時間割合が多かった。なぜなら、シール線の突端部４４が吐出端８側に大きく伸びており、ロータの回転で図中右方向に平行移動するシール線上で、早めに吐出端８に達し、吐出流路４２に開いてしまうからである。 As shown in FIG. 5, in the conventional tooth profile, there is a large proportion of time during which the flow 43 exiting to the suction side through this straight passage exists. This is because the protruding end portion 44 of the seal line greatly extends to the discharge end 8 side, reaches the discharge end 8 earlier on the seal line that translates in the right direction in the drawing by the rotation of the rotor, and opens to the discharge flow path 42. Because it ends up.

吐出端面８に開いた直通路９の面積をロータの回転に沿って表したものが図６のグラフである。このグラフは横軸に雄ロータの回転角度を、縦軸に直通路９の面積を表す。従来の歯形に比較して本実施例における直通路は開口タイミングが遅い上に面積拡大も小さいので、単位時間に漏れる量は格段に少なくなる。したがって、圧縮機性能の向上に寄与する。 FIG. 6 is a graph showing the area of the straight passage 9 opened in the discharge end face 8 along the rotation of the rotor. In this graph, the horizontal axis represents the rotation angle of the male rotor, and the vertical axis represents the area of the straight passage 9. Compared to the conventional tooth profile, the straight passage in this embodiment has a slow opening timing and a small area expansion, so that the amount leaked per unit time is remarkably reduced. Therefore, it contributes to the improvement of the compressor performance.

この歯形形状の別な利点は後進面のシール線長さを短くすることにもある。図４と図５の後進面すなわち下半分のシール線の長さを比較すればわかるように、本実施例においては区間３７，３８で鉛直に短絡するため、長さが短くなり、その分だけシール線からの内部漏洩を少なくできる。 Another advantage of this tooth profile is that the length of the seal line on the reverse surface is shortened. As can be seen by comparing the lengths of the reverse surfaces of FIG. 4 and FIG. 5, that is, the length of the lower half of the seal line, in this embodiment, since the short circuit occurs vertically in the sections 37 and 38, the length is shortened. Internal leakage from the seal wire can be reduced.

一方で、ブローホール面積が拡大するが、ブローホールは隣接する圧力差が大きくない作動室間の漏洩流路なので、性能低下への影響は小さく、ここで述べた他の向上効果に対して比較的小さい。 On the other hand, although the blowhole area is enlarged, the blowhole is a leakage flow path between adjacent working chambers where the pressure difference is not large, so the effect on performance degradation is small, compared with the other improvement effects described here Small.

吸入側への直通路９が吐出端面に８に面する時間が短い上に、面する位置も上方寄りとなるため、連通に心配のない下方に吐出ポート面積を拡大し、吐出損失を減らし性能向上する効果も期待できる。 The time when the direct passage 9 to the suction side faces the discharge end face 8 is short, and the facing position is also closer to the upper side, so the discharge port area is expanded downward without worrying about communication, and the discharge loss is reduced. The improvement effect can also be expected.

ロータを収納するケーシングの加工誤差や熱変形，ガス圧変形により、運転時の両ロータの中心距離は意図したものから変化することは通常おこりえる。その場合、作動室に油を注入しながらロータ歯面を接触回転させる方式の圧縮機では、意図したのと異なる歯形上の部分で雌雄ロータが接触することになる。通常運転時には問題になることが少ないが、吸入と吐出の圧力条件によって歯面分離振動した場合には、回転伝達のみならず歯面間の衝突を繰り返し、振動騒音の増大や、材料強度が不十分なときには歯面の損傷に至ることもありえる。 Due to processing errors, thermal deformation, and gas pressure deformation of the casing that houses the rotor, it is usually possible that the center distance between the rotors during operation changes from the intended one. In that case, in the compressor of the type in which the rotor tooth surface is contact-rotated while injecting oil into the working chamber, the male and female rotors come into contact with each other on the tooth profile different from the intended one. In normal operation, there are few problems, but when tooth surface separation vibration occurs due to suction and discharge pressure conditions, not only rotation transmission but also collision between tooth surfaces is repeated, increasing vibration noise and reducing material strength. When sufficient, tooth surface damage can occur.

特に公知例でとりあげた従来の歯形では、最も接触しやすい圧力角が最小となる部分が歯形上の特定部分に限られ、中心距離の変化に対して接触位置が動きやすかった。また、同じ理由により接触面積の拡大に限界があり、歯面分離振動による衝撃に十分な強度を確保しにくかった。 In particular, in the conventional tooth profile taken up as a publicly known example, the portion where the pressure angle that is most likely to contact is the smallest is limited to a specific portion on the tooth profile, and the contact position is easy to move with respect to the change in the center distance. For the same reason, there is a limit to the expansion of the contact area, and it has been difficult to ensure sufficient strength against impacts caused by tooth surface separation vibration.

歯面上にインボリュート曲線を採用した利点は動力伝達用の一般の歯車と同様に中心距離が変化してもその曲線上の全域での接触が維持されることにある。特に本実施例では前進面と後進面の両側にインボリュート曲線を持つことにより、歯面分離振動が発生し前進面と後進面で交互に雌雄の歯面が衝突した場合でも、両面で広い接触面積を確保し歯面損傷を防止できる。また、接触面積が広いことにより、歯面間に介在する油のダンピング効果を活用し、衝突時にも金属面どうしの接触に至らない程度に衝撃を抑制する効果もある。これにより、たとえ歯面分離振動が発生しても、大幅な騒音増加とならず、歯面分離振動を許容した設計も可能となる。 The advantage of adopting an involute curve on the tooth surface is that, as with a general gear for power transmission, even if the center distance changes, contact over the entire area of the curve is maintained. In particular, in this embodiment, there are involute curves on both sides of the advancing surface and the reversing surface, so that even if the tooth surface separation vibration occurs and the male and male tooth surfaces collide alternately on the advancing surface and the reversing surface, a wide contact area on both sides To prevent tooth surface damage. Further, since the contact area is wide, the damping effect of the oil interposed between the tooth surfaces is utilized, and there is also an effect of suppressing the impact to the extent that the metal surfaces do not come into contact with each other even at the time of collision. As a result, even if tooth surface separation vibration occurs, the noise does not increase significantly, and a design that allows tooth surface separation vibration is also possible.

本実施例で述べた３つの改良点は各々単独でも効果があるが、組み合わせることにより、更なる相乗効果を享受できる。 Each of the three improvements described in the present embodiment is effective even when used alone, but when combined, a further synergistic effect can be enjoyed.

第２の手段による性能向上を目的とした雄歯形の前進面の区間１１，１２の円弧と区間１２，１３（雌歯形の前進面の区間２１，２２の円弧と区間２２，２３）の歯形形状は、一方では雌ロータに作用するガストルクを低下させ、歯面分離振動を誘発しやすくなる短所を有する。しかし、第１の手段により前進面と後進面にインボリュート曲線を持つ本実施例においては歯面分離振動を許容できるため、性能向上効果を十分に発揮できるように前進面形状を選択し、広い圧力範囲で圧縮機を使用できるようになる。 Tooth profile shape of arcs and sections 12 and 13 of male tooth advancement surfaces and sections 12 and 13 (arcs and sections 22 and 22 of female tooth advancement surfaces and sections 22 and 23) for the purpose of improving performance by the second means On the other hand, the gas torque acting on the female rotor is reduced, and tooth surface separation vibration is easily induced. However, since the tooth surface separation vibration can be allowed in this embodiment having the involute curves on the forward surface and the reverse surface by the first means, the forward surface shape is selected so that the performance improvement effect can be sufficiently exhibited, and the wide pressure A compressor can be used in the range.

吸入端７における第３の手段による区間１６，１７による雌雄ロータの接触開始は点ではなく長さを持った圧力範囲を歯面上に出現させるため、両ロータに作用するガストルクを不連続的に変化させ加振力となる。ガス圧条件によっては、これが歯面分離振動の要因となりうるため、第３の手段の短所となる場合もある。これも第１の手段と組み合わせることにより、歯面分離にかかわらず後進面の歯形形状を決定できるようになるため相乗効果が期待できる。 Since the contact of the male and female rotors by the sections 16 and 17 by the third means at the suction end 7 appears not on the point but on the tooth surface, the gas torque acting on both rotors is discontinuously generated. Change to be an excitation force. Depending on the gas pressure conditions, this can be a factor of tooth surface separation vibration, which may be a disadvantage of the third means. By combining this with the first means, it becomes possible to determine the tooth profile shape of the reverse surface regardless of the tooth surface separation, so that a synergistic effect can be expected.

図４で示したように第２の手段により高圧側の作動室５からシール線を横断して噴出する流体のうち、区間３１，３２から水平に噴出するものは、吐出端からの直通路からの流れ４３があると、流れ方向を上方に曲げられ、性能向上効果が減退してしまう。そのため、第３の手段と兼用することにより、十分な性能向上効果を期待することができる。 As shown in FIG. 4, among the fluid ejected from the high pressure side working chamber 5 across the seal line by the second means, the fluid ejected horizontally from the sections 31 and 32 is from the straight passage from the discharge end. If there is a flow 43, the flow direction is bent upward, and the performance improvement effect declines. Therefore, a sufficient performance improvement effect can be expected by combining the third means.

本実施例においては油冷式スクリュー圧縮機を題材に説明したが、作動室に油を注入しないオイルフリー式であっても同様に適用できる。また、図２に示したように、雄ロータ４枚，雌ロータ５枚の歯数の例で説明したが、他の歯数の組み合わせであっても同様に適用できる。 In this embodiment, the oil-cooled screw compressor has been described as a theme, but the present invention can be similarly applied to an oil-free type in which oil is not injected into the working chamber. Further, as shown in FIG. 2, the example of the number of teeth of four male rotors and five female rotors has been described, but the present invention can be similarly applied to combinations of other numbers of teeth.

本実施例の第１の手段により、運転時の吸入と吐出の圧力条件が悪く歯面分離振動の発生が避けられない場合であっても、歯面の衝突の衝撃を抑制し外部への騒音を小さく抑える。また、衝撃緩和が歯面の損傷を防止する効果もある。 Even if the suction and discharge pressure conditions during operation are poor and the occurrence of tooth surface separation vibration is unavoidable due to the first means of this embodiment, the impact of tooth surface collision is suppressed and noise to the outside is suppressed. Keep it small. Further, the impact relaxation has an effect of preventing the tooth surface from being damaged.

また、本実施例の第２の手段により、吐出端面から吸入側への直通路が現れる時間割合が小さく、なおかつ直通路がある時間帯でもその断面積が小さい。また、後進面のシール線長さが短くなる。これら内部漏洩流路の面積縮小により内部漏洩を低減し圧縮機のエネルギ効率向上すなわち高性能化が図れる。 Further, the second means of the present embodiment has a small time ratio in which the direct passage from the discharge end surface to the suction side appears, and the cross-sectional area is small even in a time zone where the direct passage is present. Further, the length of the seal line on the reverse surface is shortened. By reducing the area of these internal leakage passages, internal leakage can be reduced and the energy efficiency of the compressor can be improved, that is, the performance can be improved.

また、本実施例の第３の手段により、ロータ間隙間を通って高圧となった圧縮室から吸入側面に吹き出す高温高圧の被圧縮気体や油の噴出方向を軸方向か半径方向のいずれかに制限し、斜め方向から吸入してくる被圧縮気体の流れを阻害しない。そのため、吸入圧損や吸入過熱が抑制され、圧縮機の性能を向上する。

Further, the third means of the present embodiment, either axial or radial ejection direction of the compressed gas and oil of high temperature and high pressure to be blown into the intake side from the compression chamber becomes high pressure through the gap between the rotor The flow of the compressed gas sucked from an oblique direction is not obstructed. Therefore, suction pressure loss and suction overheating are suppressed, and the performance of the compressor is improved.

更に、各手段を組み合わせることにより、上記第１〜第３の手段個別の効果に加えて次の効果がある。第２の手段は歯面分離振動が発生しやすくなる副作用を伴うが、第１の手段を併用することにより、その欠点を補える。第３の手段による効果は吸入側への直通路からの漏洩量が多いと、水平方向への噴出流を上方に曲げてしまうため、第２の手段を併用することにより、その効果を十分に発揮することができる。第３の手段は雌ロータに作用するガストルクの変化を大きくする副作用があり、それにより条件によっては歯面分離しやすくなることもあるが、第１の手段を併用することによりその欠点を補える。 Further, by combining the respective means, the following effects can be obtained in addition to the individual effects of the first to third means. The second means has a side effect that the tooth surface separation vibration easily occurs, but the disadvantage can be compensated by using the first means together. The effect of the third means is that if the amount of leakage from the direct passage to the suction side is large, the jet flow in the horizontal direction is bent upward, so that the effect can be sufficiently obtained by using the second means together. It can be demonstrated. The third means has a side effect of increasing the change in gas torque acting on the female rotor, and depending on the conditions, the tooth surface may be easily separated, but the disadvantage can be compensated by using the first means together.

本発明の一実施例における雌雄ロータの歯形を説明するロータ断面拡大図。The rotor cross-sectional enlarged view explaining the tooth profile of the male and female rotor in one Example of this invention. 本発明の一実施例におけるスクリュー圧縮機の軸方向の断面図。The sectional view of the axial direction of the screw compressor in one example of the present invention. 後進面における同時接触線で接触する角度での歯形を説明するロータ断面拡大図。The rotor cross-sectional enlarged view explaining the tooth profile in the angle which contacts by the simultaneous contact line in a reverse surface. ロータの側面から見たシール線の形状と吸入側への噴出を説明するスクリュー圧縮機の断面略図。The cross-sectional schematic of the screw compressor explaining the shape of the seal line seen from the side surface of the rotor, and the ejection to the suction side. 従来の歯形のシール線形状を説明するスクリュー圧縮機の断面略図。The cross-sectional schematic of the screw compressor explaining the seal line shape of the conventional tooth profile. 本発明と従来の歯形による吸入側への直通路の面積変化を示すグラフ。The graph which shows the area change of the direct passage to the suction side by this invention and the conventional tooth profile.

符号の説明Explanation of symbols

１雄ロータ
２雌ロータ
３ケーシング
４ボア
５高圧作動室
６低圧作動室
７吸入端
８吐出端
９吸入側への直通路
１１雄ロータの歯先
１２〜２０雄歯形上の点
２１雌ロータの歯底
２２〜３０雌歯形上の点
３１〜４０シール線（接触点の軌跡となる線）上の点
４１吸入流路
４２吐出流路
４３直通路を通って吸入側に抜ける流れ
４４シール線の突端部 DESCRIPTION OF SYMBOLS 1 Male rotor 2 Female rotor 3 Casing 4 Bore 5 High pressure working chamber 6 Low pressure working chamber 7 Suction end 8 Discharge end 9 Direct passage 11 to the suction side Tooth tip 12-20 of a male rotor Point 21 on male tooth shape 21 Tooth of a female rotor Bases 22 to 30 Points 31 to 40 on the female tooth shape Points 41 on the seal line (line that becomes the locus of the contact point) Suction flow path 42 Discharge flow path 43 Flow through the straight passage to the suction side 44 Tip of the seal line Part

Claims

平行な二軸の回りを互いに噛み合って回転し、それぞれ表面上でねじれた歯を有する一対の雄ロータ及び雌ロータを有し、前記雄ロータの軸に垂直な断面において前記雄ロータの歯の大部分が前記雄ロータの軸を中心とする雄ピッチ円の外側にあり、前記雌ロータの軸に垂直な断面において前記雌ロータの歯の大部分が前記雌ロータの軸を中心とする雌ピッチ円の内側にあるスクリューロータ対を備えたスクリュー圧縮機において、
前記両ロータの軸に垂直な断面上における輪郭形状を表す歯形曲線は、前記雄ロータのピッチ円より外側で、前記雌ロータのピッチ円半径より内側に相当する前進面ならびに後進面上の両方にインボリュート曲線を有し、前記雌ロータの歯底点から前進面側が、最初の区間がピッチ点を中心とする円弧、前記雄ロータの歯先点から後進面側が、最初の区間が前記ピッチ点を中心とする円弧の半径よりも小さい半径の第１の円弧で、次の区間が該第１の円弧に滑らかに連続し、かつ曲がり方向が同じの第２の円弧で、該第２の円弧の中心は雄ピッチ円上にある歯形を有するスクリュー圧縮機。 A pair of male and female rotors rotating in mesh with each other around two parallel axes, each having a twisted tooth on the surface, and having a large tooth diameter of the male rotor in a cross section perpendicular to the axis of the male rotor A female pitch circle with a portion outside the male pitch circle centered on the axis of the male rotor and a majority of the teeth of the female rotor centered on the axis of the female rotor in a cross section perpendicular to the axis of the female rotor In a screw compressor with a screw rotor pair inside,
The tooth profile curve representing the contour shape on the cross section perpendicular to the axes of the two rotors is on both the forward surface and the reverse surface corresponding to the outside of the pitch circle of the male rotor and the inside of the pitch circle radius of the female rotor. It has an involute curve, the forward surface side from the root point of the female rotor, the first section is an arc centered on the pitch point, the reverse surface side from the tooth tip point of the male rotor, the first section is the pitch point A first arc having a radius smaller than the radius of the center arc, the second section is a second arc that smoothly continues to the first arc and has the same bending direction, and the second arc Screw compressor with tooth profile centered on male pitch circle.

平行な二軸の回りを互いに噛み合って回転し、それぞれ表面上でねじれた歯を有する一対の雄ロータ及び雌ロータを有し、前記雄ロータの軸に垂直な断面において前記雄ロータの歯の大部分が前記雄ロータの軸を中心とする雄ピッチ円の外側にあり、前記雌ロータの軸に垂直な断面において前記雌ロータの歯の大部分が前記雌ロータの軸を中心とする雌ピッチ円の内側にあるスクリューロータ対を備えたスクリュー圧縮機において、
前記両ロータの軸に垂直な断面上における輪郭形状を表す歯形曲線は、前記雄ロータのピッチ円より外側で、前記雌ロータのピッチ円半径より内側に相当する前進面ならびに後進面上の両方にインボリュート曲線を有し、前記雌ロータの歯底点から前進面側が、最初の区間がピッチ点を中心とする円弧を形成する曲線からなり、前記雄ロータの歯先点から後進面側が、最初の区間が前記ピッチ点を中心とする円弧の半径よりも小さい半径の第１の円弧で、次の区間が該第１の円弧に滑らかに連続し、かつ曲がり方向が同じの第２の円弧で、該第２の円弧の中心は雄ピッチ円上にある歯形を有し、
前記雌ロータの歯底点から前進面側の最初の区間に続く次の区間において、前記雌ロータと前記雄ロータとの接触点が、前記両ロータの軸に垂直な異なる断面上に形成され、前記接触点の全てが前記雌ロータの最初の区間の終点を通り前記両ロータの軸に平行な同一水平線上に位置することを特徴とするスクリュー圧縮機。 A pair of male and female rotors rotating in mesh with each other around two parallel axes, each having a twisted tooth on the surface, and having a large tooth diameter of the male rotor in a cross section perpendicular to the axis of the male rotor A female pitch circle with a portion outside the male pitch circle centered on the axis of the male rotor and a majority of the teeth of the female rotor centered on the axis of the female rotor in a cross section perpendicular to the axis of the female rotor In a screw compressor with a screw rotor pair inside,
The tooth profile curve representing the contour shape on the cross section perpendicular to the axes of the two rotors is on both the forward surface and the reverse surface corresponding to the outside of the pitch circle of the male rotor and the inside of the pitch circle radius of the female rotor. It has an involute curve, the forward surface side from the root point of the female rotor is a curve in which the first section forms an arc centered on the pitch point, and the reverse surface side from the tooth tip point of the male rotor is the first The section is a first arc having a radius smaller than the radius of the arc centered on the pitch point, the next section is a second arc that smoothly continues to the first arc and has the same bending direction, the center of the circular arc of the second will have a tooth profile that is on the male pitch circle,
In the next section following the first section on the advancing surface side from the root point of the female rotor, contact points between the female rotor and the male rotor are formed on different cross sections perpendicular to the axes of the two rotors, The screw compressor characterized in that all of the contact points are located on the same horizontal line passing through the end point of the first section of the female rotor and parallel to the axes of the two rotors .