JPS6060320A - Tilting pad bearing - Google Patents

Abstract

PURPOSE:To expand the range for changing bearing conditions by changing dimensions such as a radius of curvature of each of pad inner surfaces positioned in the horizontal direction and in the vertical direction to give the difference between the rigidities of oil films in the horizontal direction and in the vertical direction of a bearing. CONSTITUTION:The drawing shows the case that the center of a bearing is conformed with the center of rotation. A bearing shell 1 is constituted by fixedly connecting semicircular shell members 2 and 3, pads 4, 5, 6 and 7 are housed in the inner side of its inner radius RH, and each of pads 4 to 7 is swingingly movable about a pivot part as a fulcrum. Clearances between a rotating shaft 8 and the inner surfaces of the pads are not similar, and radii of curvature, thicknesses, bearing clearances, widths and circular are angles of the pad inner surfaces are not constant. The differences are thus given in the dimensions of the pads in the horizontal direction and in the vertical direction of the bearing, thereby the rigidities of the bearing being differentiated between the respective directions.

Description

【発明の詳細な説明】 この発明は、ターボ機械等の不安定振動を防止するため
に適用さｎるティルティングパッド軸受の改良に関する
ものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a tilting pad bearing that is applied to prevent unstable vibrations in turbo machines and the like.

テイルテイングパッド軸受は安定性が大きく、ターボ機
械等の不安定振動を防止する軸受として多用されている
。ところが、従来のこの種軸受は各パッドの内面の曲率
半径、パッドの厚さ、パッドの幅、パッドの円弧角が均
一であるために、特に高速回転・軽荷重の軸受条件の場
合に、回転軸の中心が軸受の中心に近づき、各パッドの
内面に形成さ扛る油膜の動圧作用が均一化さ扛、又軸受
の水平方向と鉛直方向の油膜の剛性も均一化されるため
に、不安定振動を防止するという当所の目的が達成され
ない。Tailing pad bearings have great stability and are often used as bearings to prevent unstable vibrations in turbo machinery, etc. However, in conventional bearings of this type, the radius of curvature of the inner surface of each pad, the thickness of the pad, the width of the pad, and the arc angle of the pad are uniform, so the rotational As the center of the shaft approaches the center of the bearing, the dynamic pressure effect of the oil film formed on the inner surface of each pad becomes uniform, and the rigidity of the oil film in the horizontal and vertical directions of the bearing is also equalized. Our objective of preventing unstable vibrations is not achieved.

そこでターボ機械の羽根車の流体力学的連成作用に起因
して生ずる軸系の不安定振動を防止するうえで、テイル
テイングパッド軸受におけるパッド数が安定限かに及ぼ
す影響について検討した結果、パッド数によって軸受時
ｊ性の等方性が異なシ、そして非等方剛性を有するほど
軸受の安定限界が大きくなる範囲が存在することが確認
された。Therefore, in order to prevent unstable vibrations in the shaft system caused by the hydrodynamic coupling of the impeller of a turbomachine, we investigated the effect of the number of pads in a tailing pad bearing on the stability limit. It was confirmed that there is a range in which the isotropy of the bearing characteristics differs depending on the number of bearings, and the stability limit of the bearing increases as the anisotropic stiffness increases.

更に上記非等方剛性を与える方法として、軸受内の各パ
ッドにおいてプレロード係数に差異を与え、これが軸受
の安定限界に及ぼす影響について検討したところ、やは
り軸受の安定限界が向上する範囲が存在し、又この非等
方化の最適値が存在することを確認した。Furthermore, as a method of imparting the above-mentioned anisotropic stiffness, we varied the preload coefficient for each pad within the bearing and examined the effect this had on the stability limit of the bearing. As expected, there was a range in which the stability limit of the bearing could be improved. We also confirmed that an optimal value for this anisotropy exists.

この発明は、以上の認識に基づき、ターボ機械の羽根車
などに働く流体力学的速成作用に起因した回転軸・軸受
系の自励振動を防止するうえで、軸受剛性の最適化を計
るために、従来の軸受の剛性均一化の傾向を変更し、故
意に剛性を不均一にすることによシ、軸受条件の変更範
囲を拡大し得る具体的手段を提供することを目的として
なされたものである。Based on the above recognition, this invention aims to optimize bearing rigidity in order to prevent self-excited vibration of the rotating shaft/bearing system caused by the hydrodynamic fast-forming action acting on the impeller of turbomachinery. This was done with the aim of providing a concrete means for expanding the range of changes in bearing conditions by changing the tendency of conventional bearings to make the stiffness uniform and intentionally making the stiffness non-uniform. be.

すなわちこの発明は、軸受シェル内に配置された複数個
のパッドのうちで、水平方向と鉛直方向に位置する各パ
ッド内面の曲率半径、厚さ、幅、円弧角の寸法諸元をそ
れぞｎ個別或は組み合わせて変更し、各パッド内面と回
転軸外周との間に形成される油膜間隙の寸法を変え、軸
受の水平方向と鉛直方向の油膜の剛性に差異を持たせる
ようにしたことを特徴とするものであり、以下その一実
施例を示す図面に基づいて説明する。In other words, the present invention calculates the dimensional specifications of the radius of curvature, thickness, width, and arc angle of the inner surface of each pad located in the horizontal and vertical directions among a plurality of pads arranged in a bearing shell. By changing the dimensions of the oil film gap formed between the inner surface of each pad and the outer periphery of the rotating shaft, either individually or in combination, the rigidity of the oil film in the horizontal and vertical directions of the bearing is made to differ. This is a characteristic feature of the present invention, and will be described below based on the drawings showing one embodiment thereof.

第１図はこの発明に係わるチルティングパッド軸受の組
立て構造を示す正面図であり、軸受中心と回転軸心が一
致した場合を示している。ところで同図において、軸受
シェル（１）は上下２つの半円形シェル部材＋２１＋３
）を接合固定して構成さｎｌその内半径（ＲＨ）の内側
にパッド（４）（５Ｈ６）（７）が収設され、各パッド
（４）（５）（６）（７）の中央背面はそれぞれ線接触
してピボット構造をもって上記軸受シェル（１）に係着
されている。しかって各パッド（４１１５１ｆａ）（７
）はピボット部を支点として揺動輪し得るものである。FIG. 1 is a front view showing the assembly structure of the tilting pad bearing according to the present invention, and shows a case where the center of the bearing and the axis of rotation coincide. By the way, in the same figure, the bearing shell (1) consists of two upper and lower semicircular shell members +21+3.
) is bonded and fixed, and pads (4) (5H6) (7) are housed inside its inner radius (RH), and the central back surface of each pad (4) (5) (6) (7) is are each connected to the bearing shell (1) with a pivot structure in line contact. However, each pad (41151fa) (7
) can be used as a swinging wheel using the pivot part as a fulcrum.

又各パッド（４）（５）（６）（７）の内面の曲率半径
（ＲｓＸＲ意）（Ｒ１）（Ｒ４）と回転軸（８）の半径
（ＲＩ）との間には所定の間隙が存在し、ここに油膜が
形成されるものであり、図示されていないが、軸受の両
側にはシールカバーが付設され、軸とパッドと軸受シェ
ルとの間に油が満たされ、油浴状態となり、しかもシー
ルカバーと軸との隙間を通じて油がオーバフローするよ
うな軸封構造が採用される。Also, there is a predetermined gap between the radius of curvature (RsXR) (R1) (R4) of the inner surface of each pad (4) (5) (6) (7) and the radius (RI) of the rotating shaft (8). Although not shown, seal covers are attached to both sides of the bearing, and oil is filled between the shaft, pad, and bearing shell, creating an oil bath. Moreover, a shaft seal structure is adopted in which oil overflows through the gap between the seal cover and the shaft.

なおここで軸受の中心とパッド内面の曲率半径の中心と
は必ずしも一致しておらず、回転軸（８）と、各パッド
（４）（５）（６）（７）内面との間隙は均一ではなく
、各パッドｆ４）（５）（６１（７）について最小の間
隙が存在し、これを軸受すきま（０１）（０１）　（０
１）（０４）で表示している。なお図において、（Ｈｓ
）（Ｈ富）（Ｈｓ　）（Ｈ４）　は各パッド（４）（５
）（６）（））の中央の厚さであり、又（α１）（α２
）（α１）（α４）は各パッド（４）（５）（６）（η
の円弧角を表示している。更に第２図及び第３図は、第
１図における矢視１１−１．■−■断面図であり、図中
（Ｌｌ）（Ｌｓ　）（Ｌｍ）（Ｌｌ）はパッド幅を示し
ている。Note that the center of the bearing and the center of the radius of curvature of the inner surface of the pads do not necessarily coincide, and the gaps between the rotating shaft (8) and the inner surface of each pad (4), (5), (6), and (7) are uniform. Instead, there is a minimum gap for each pad f4)(5)(61(7), which is defined as bearing clearance (01)(01)(0
1) (04). In the figure, (Hs
) (H wealth) (Hs ) (H4) is each pad (4) (5
)(6)()), and (α1)(α2
)(α1)(α4) are each pad (4)(5)(6)(η
The arc angle of is displayed. Further, FIGS. 2 and 3 are shown in the direction of arrow 11-1 in FIG. It is a sectional view taken along line 1--2, and (Ll), (Ls), (Lm), and (Ll) in the figure indicate pad widths.

ところで従来の軸受では各パッド内面の曲率半径、パッ
ドの厚さ、軸受すきま、パッドの幅、パッドの円弧角が
すべて均一に構成されて込るが、これに対しこの発明の
軸受においては、パッド内面の曲率半径Ｒｓ　＝Ｒ１、
Ｒ窒−Ｒ４１ＲＩ　＞　Ｒｓあるいはパッドの厚さＨ，
＝　）Ｉ、　、　Ｈ，＝Ｈ４，Ｈ，）　Ｈ，とすること
により、軸受すきまＱ、　−Ｑ、　、　Ｑ、　−Ｑ、　
、　Ｑ□〈０寓とし、又パッドの幅Ｉ１１　””　Ｉ’
ｍ　＊　Ｉ’ｍ　＝　Ｌｌ　ｗ　１１１〉Ｌ□あるいは
パッドの円弧角αｌ−α１．町；α４１α１〉α冨とす
ることによって、軸受の水平方向と鉛直方向にあるパッ
ドの寸法諸元に差異をもたせたものであり、これによっ
て軸受の剛性をそれぞれの方向の間で相違させている。By the way, in conventional bearings, the radius of curvature of the inner surface of each pad, the thickness of the pad, the bearing clearance, the width of the pad, and the arc angle of the pad are all uniform, but in the bearing of the present invention, the pad The radius of curvature of the inner surface Rs = R1,
R Nitrogen-R41RI > Rs or pad thickness H,
By setting = ) I, , H, = H4, H,) H, the bearing clearance Q, -Q, , Q, -Q,
, Q
m * I'm = Ll w 111〉L□ or the arc angle αl-α1 of the pad. By setting α41α1〉α, the dimensions of the pads in the horizontal and vertical directions of the bearing are different, thereby making the rigidity of the bearing different in each direction. .

なお図面に示す実施例では、パッド数４個の場合である
が、こｎを５個又はそれ以上収設する場合においても、
適宜寸法諸元を変え軸受剛性に非等方性を与えることが
でき、その選択は自由である。In the embodiment shown in the drawings, the number of pads is four, but even if five or more pads are installed,
It is possible to give anisotropy to the bearing rigidity by changing the dimensions as appropriate, and the selection is free.

以上のように、従来の軸受では、各パッドの寸法諸元が
等しいために、高速回転、軽荷重条件下で軸受の剛性が
必然的に等方性をもち、ターボ機械羽根車などに働く流
体力学的達成作用に起因する回転軸、軸受系の自励振動
を防止するうえで、軸受条件を最適化するために軸受剛
性の非等方性を変数に選定できなかった。これに対しこ
の発明の軸受では各パッドの寸法諸元を相違させて軸受
剛性を水平方向と鉛直方向とで非等方性を与えたもので
あυ、上記振動を防ぐための広範囲な軸受特性の選定が
可能である。なおちなみに従来のものとの比較実験を試
みた結果、第４図に示すよううにこの発明による軸受の
安定性の向上効果が立証された。As described above, in conventional bearings, since the dimensions of each pad are the same, the stiffness of the bearing is inevitably isotropic under high-speed rotation and light load conditions, and the fluid acting on turbomachine impellers, etc. In order to prevent self-excited vibrations of the rotating shaft and bearing system caused by mechanical effects, it was not possible to select the anisotropy of the bearing stiffness as a variable to optimize the bearing conditions. On the other hand, in the bearing of the present invention, the dimensions of each pad are different to give the bearing stiffness anisotropy in the horizontal and vertical directions. It is possible to select Incidentally, as a result of a comparative experiment with a conventional bearing, the effect of improving the stability of the bearing according to the present invention was proved as shown in FIG.

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

第１図はこの発明の一実施例を示す正面図、第２図Ｖｉ
第１図における■−■断面図、第３図は同ＩＩＩ−ＩＩ
Ｉ断面図、第４図は従来のものとの比較実験結果を示す
線図である。 （１）は軸受シェル、（４）＋５）（ａ）（７）はパッ
ド、（８）は回転軸、（Ｒ１）〜（Ｒ４）はパッド内面
の曲率半径、（ａり〜（０４）は軸受すきま、（Ｈｌ）
〜（Ｈ４）はパッドの中央の厚さ、（α、）〜（α４）
はパッドの円弧角、（Ｌｓ）〜（Ｒ４）はパッド幅。 特許出願人　日立造船株式会社FIG. 1 is a front view showing an embodiment of the present invention, and FIG.
■-■ sectional view in Figure 1, Figure 3 is III-II
I cross-sectional view, FIG. 4 is a diagram showing the results of a comparative experiment with the conventional one. (1) is the bearing shell, (4) + 5) (a) (7) is the pad, (8) is the rotating shaft, (R1) to (R4) is the radius of curvature of the inner surface of the pad, (a to (04) is Bearing clearance, (Hl)
~(H4) is the thickness of the center of the pad, (α,) ~(α4)
is the arc angle of the pad, and (Ls) to (R4) are the pad widths. Patent applicant Hitachi Zosen Corporation

Claims (1)

【特許請求の範囲】[Claims] 軸受シェル内に配置された複数個のパッドのうちで、水
平方向と鉛直方向に位置するそｎぞれのパッド内面の曲
率半径、厚さ、幅、円弧角の寸法諸元を個別或は組み合
わせて変更し、各パッド内面と回転軸外周との間に形成
さ扛る油膜間隙の寸法を変え、軸受の水平方向と鉛直方
向の油膜を剛性に差異を持たせるようにしたことを特徴
とするテイルテイングパッド軸受。Among the multiple pads arranged in the bearing shell, the dimensional specifications of the radius of curvature, thickness, width, and arc angle of the inner surface of each pad located in the horizontal and vertical directions, individually or in combination. The bearing is characterized in that the size of the oil film gap formed between the inner surface of each pad and the outer periphery of the rotating shaft is changed, and the rigidity of the oil film in the horizontal and vertical directions of the bearing is made to differ. Tailing pad bearing.