JP3620997B2 - Improvement of non-circular gear and non-circular gear type flow meter using the same - Google Patents
Improvement of non-circular gear and non-circular gear type flow meter using the same Download PDFInfo
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- JP3620997B2 JP3620997B2 JP16264499A JP16264499A JP3620997B2 JP 3620997 B2 JP3620997 B2 JP 3620997B2 JP 16264499 A JP16264499 A JP 16264499A JP 16264499 A JP16264499 A JP 16264499A JP 3620997 B2 JP3620997 B2 JP 3620997B2
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- circular gear
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Description
【０００１】
【発明の属する技術分野】
本発明は、非円形歯車式流量計における非円形歯車の改良及びそれを用いた非円形歯車式流量計に関するものである。
【０００２】
【従来の技術】
図３は、従来のオーバル歯車を用いたオーバル歯車式流量計の概略構成図で、流入口１、流出口２を一体的に構成した計量室３内に、回転中心Ｏ１，Ｏ２を定点として、この各々の定点から回転角θ１、θ２の関数として与えられるｒ１，ｒ２の距離において転がり接触をする条件である
ｒ１＋ｒ２＝一定 …（１）
ｒ１・ｄθ１＝ｒ２・ｄθ２ …（２）
を満足するピッチ曲線
ｒｉ＝ａ／（１±ｂｃｏｓ２θｉ）（ｉ＝１，２） …（３）
（ただし、ａは相似係数、ｂは偏平度とする。）
であらわされるオーバル歯車の回転子４，５を回転自在に支承し内包する構成となっている。
【０００３】
該オーバル歯車式流量計は、周知のように、被測定流体の流入圧Ｐ１と流出圧Ｐ２の差Ｐに基づくトルク差によって、両オーバル歯車がそれぞれ矢印方向に回転され、１回転当り計量室とオーバル歯車によって形成される三ヶ月状の体積Ｖの４倍の体積の流体を送り出すものである。このオーバル歯車式流量計は、流体の物性（密度、粘度）や流速分布の影響が少ないため、小流量の感度に優れている。
ここで、ある所定時間内の流体通過量をＱ、回転数をｎ、歯車と計量室内壁との隙間よりの漏れ量をｑとすれば、
Ｑ＝４Ｖｎ＋ｑ …（４）
で表わされ、漏れ量ｑが計量誤差となる。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記漏れ量ｑは、歯先隙間の漏れｑδと、側面隙間の漏れｑＳが存在し、特に、微少流量域では回転子である非円形歯車の回転と流量の比例関係が失われ、普通では無視できる歯先隙間による漏れｑδも誤差として問題となる。
ｑ＝ｑδ＋ｑＳ …（５）
【０００５】
図４は、歯車の歯先と計量室のすきまを拡大した図で、図４において、被測定流体の流入圧Ｐ１と流出圧Ｐ２の圧力差をＰ、非測定流体の粘度をμ、歯先と計量室の壁面の間の隙間をδ、歯先の周速度をＵ、歯先が計量室の壁面に接している歯の数をｚ０、歯の厚みをｔ、歯幅をｗとすると、歯先隙間の漏れ量ｑδは
ｑδ＝（Ｐ・δ３／６・ｚ０・ｔ・μ−Ｕ・δ）ｗ …（６）
で表される。
【０００６】
本発明は、上述のごとき非円形歯車式流量計における歯先隙間の漏れ量ｑδを少なくすることにより、小流量域における計量誤差を小さくすることを目的としている。
【０００７】
【課題を解決するための手段】
式（６）によれば、歯先隙間の漏れ量ｑδを少なくするためには、歯車の歯先が計量室の壁面に接している歯の数ｚ０を多くすればよいことが分かる。
請求項１に記載の発明は、ピッチ曲線の長径部および短径部は計量室と同芯の円弧とし、その間をオーバル曲線で結合したことを特徴とする非円形歯車式流量計に用いる非円形歯車に係るものである。
【０００８】
請求項２に記載の発明は、流量に応じて噛合回転する１対のオーバル歯車を有するオーバル歯車式流量計において、各オーバル歯車を、請求項１に記載の非円形歯車を用いることにより、歯車の歯先が計量室の内壁面に接している歯の数を多くし、歯先隙間からの漏れ量を少なくした流量計に係るものである。
【０００９】
【発明の実施の形態】
図１は、本発明による非円形歯車のピッチ曲線と従来のオーバル歯車のピッチ曲線を示す図である。
本発明による非円形歯車のピッチ曲線は、非円形歯車の回転中心Ｏを定点として、この定点から回転角θの関数として与えられるｒの距離において転がり接触をする条件である前記式（１）及び（２）を満足するピッチ曲線であって、
【００１０】
ここで、θ０について求めると、転がり接触条件から、Ａ〜Ｂ間の曲線の長さと、Ｃ〜Ｄ間の長さは等しいので、
【００１１】
本発明の上記式（７）で定義づけられるピッチ曲線のプロフィールで形成される非円形歯車は、長径部の中心角２×θＡにわたる円弧部分に設けられた歯車の歯先はすべて計量室の内壁と接することになる。
これに対して従来の前記式（３）で表されるオーバル曲線で形成されたオーバル歯車は、理論的には１〜３個の歯車の歯先のみが計量室の壁面に接する。
このように、従来は、せいぜい１〜３個程度の歯車の歯先が計量室の壁面に接していたのに対し、本発明では、計量室の内径と非円形歯車の歯先が等しく、中心角θＡの大きさの選択により自在に増やすことができ、好ましくは５〜７個とすることにより、歯先からの漏洩を従来のものと比べ数分の一に大幅に減少させることができる。
【００１２】
また、歯車の長径部と短径部の２つの円弧部分の間を連続した単一のオーバル曲線で結合したため、円弧とオーバル曲線の接続点Ｂ、Ｃでの接線角が連続しており、相対角加速度の変化が少なく、かつ滑らかに変化するピッチ曲線をもつ非円形歯車が実現されるため、該非円形歯車に相互に作用する慣性力が平滑となる。その結果、従来例の如く局所的に歯形が摩耗することが少なくなり、耐久性を増大するだけでなく、歯形接触圧の増大によつて生ずる摩擦トルクの変化も小さくなるため、流量計の機器精度が向上するとともに安定し、更に、運転時の騒音も減少する等極めて優れた特性の容積流量計を実現することができる。
そして、本発明による非円形歯車の長径が、計量室の内径と一致すれば、構造上、従来のオーバル歯車の回転子と取り替えることができることはいうまでもない。
【００１３】
【発明の効果】
以上のように本発明によれば、非円形歯車のピッチ曲線の長径部を、計量室と同芯の円弧にすることにより、計量室の内壁面に接する歯車の歯の数を増やすことができ、歯先隙間の漏れ量を少なくできる。
また、計量室と同芯の円弧とした長径部と、短径部の間を単一のオーバル曲線で結合したことにより、接線加速度の変動が円滑になり、オーバル歯車式流量計に特有の歯の局部的摩耗を防ぎ、計測流体の脈動化に伴う弊害を小さくすることができる。
そして、従来のオーバル歯車式流量計の計量室をそのまま利用し、用いられていたオーバル歯車を本願発明の歯車に置換するだけで、高精度な流量計に変えることができる。
【図面の簡単な説明】
【図１】本発明の非円形歯車のプロフィールを示す図である。
【図２】本発明の非円形歯車のプロフィールの第Ｉ象限の詳細図である。
【図３】従来のオーバル歯車式流量計を示す図である。
【図４】歯車の歯先と計量室のすきまを拡大した図である。
【符号の説明】
１…流入口、２…流出口、３…計量室、４，５…回転子（非円形歯車）、１０…本発明による非円形歯車のプロフィール、２０…従来のオーバル歯車のプロフィール。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a non-circular gear in a non-circular gear-type flow meter and a non-circular gear-type flow meter using the same.
[0002]
[Prior art]
FIG. 3 is a schematic configuration diagram of an oval gear type flow meter using a conventional oval gear. In a measuring chamber 3 in which an
r 1 · dθ 1 = r 2 · dθ 2 (2)
Pitch curve r i = a / (1 ± b cos 2θ i ) ( i = 1,2) (3)
(Where a is the similarity coefficient and b is the flatness)
The oval gear rotors 4 and 5 represented by the above are rotatably supported and included.
[0003]
The oval gear flow meter, as is well known, the torque difference based on the difference P inflow pressure P 1 and the outlet pressure P 2 of the fluid to be measured, both oval gear is rotated in the arrow direction, per revolution Weighing A fluid having a volume four times as large as the three-month volume V formed by the chamber and the oval gear is sent out. This oval gear type flow meter is excellent in the sensitivity of a small flow rate because it is less affected by the physical properties (density, viscosity) and flow velocity distribution of the fluid.
Here, if the fluid passing amount within a certain predetermined time is Q, the rotational speed is n, and the leakage amount from the gap between the gear and the measuring chamber inner wall is q,
Q = 4Vn + q (4)
The leakage amount q is a measurement error.
[0004]
[Problems to be solved by the invention]
However, the leak amount q includes a tip gap clearance qδ and a side clearance leak qS, and the proportional relationship between the rotation of the non-circular gear, which is a rotor, and the flow rate is lost particularly in a minute flow rate range. Then, the leakage qδ due to the tooth tip gap which can be ignored also becomes a problem as an error.
q = qδ + qS (5)
[0005]
Figure 4 is a enlarged view of a gap tooth tips and the metering chamber of the gear, in FIG. 4, P the pressure difference between the inlet pressure P 1 and the outlet pressure P 2 of the fluid to be measured, the viscosity of the non-measured fluid mu, The gap between the tooth tip and the wall surface of the measuring chamber is δ, the peripheral speed of the tooth tip is U, the number of teeth that are in contact with the wall surface of the measuring chamber is z 0 , the tooth thickness is t, and the tooth width is w When the leakage amount Qderuta addendum clearance qδ = (P · δ 3/ 6 · z 0 · t · μ-U · δ) w ... (6)
It is represented by
[0006]
An object of the present invention is to reduce a measurement error in a small flow rate region by reducing a leak amount qδ of a tooth gap in a non-circular gear type flow meter as described above.
[0007]
[Means for Solving the Problems]
According to the equation (6), it can be seen that in order to reduce the leak amount qδ of the tooth gap, it is only necessary to increase the number z 0 of the teeth where the tooth tip of the gear is in contact with the wall surface of the measuring chamber.
According to the first aspect of the present invention, the major axis and the minor axis of the pitch curve are arcs that are concentric with the measuring chamber and are connected by an oval curve between them. It concerns gears.
[0008]
According to a second aspect of the present invention, there is provided an oval gear type flow meter having a pair of oval gears that mesh and rotate in accordance with a flow rate, and each oval gear is a gear by using the non-circular gear according to the first aspect. This invention relates to a flowmeter in which the number of teeth in contact with the inner wall surface of the measuring chamber is increased and the amount of leakage from the tooth gap is reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a pitch curve of a non-circular gear according to the present invention and a pitch curve of a conventional oval gear.
The pitch curve of the non-circular gear according to the present invention is a condition in which rolling contact is made at a distance r given from the fixed point as a function of the rotation angle θ with the rotation center O of the non-circular gear as a fixed point. A pitch curve satisfying (2),
[0010]
Here, when calculating | requiring about (theta) 0 , since the length of the curve between A-B and the length between C-D are equal from rolling contact conditions,
[0011]
In the non-circular gear formed by the profile of the pitch curve defined by the above formula (7) of the present invention, all the tooth tips of the gear provided in the arc portion extending over the
On the other hand, in the conventional oval gear formed by the oval curve represented by the formula (3), theoretically, only the tooth tips of 1 to 3 gears are in contact with the wall surface of the measuring chamber.
As described above, conventionally, the tooth tips of about 1 to 3 gears are in contact with the wall surface of the measuring chamber, whereas in the present invention, the inner diameter of the measuring chamber is equal to the tooth tip of the non-circular gear, By selecting the size of the angle θ A , it can be increased freely. Preferably, by setting the number to 5 to 7, leakage from the tooth tip can be greatly reduced by a fraction of that of the conventional one. .
[0012]
Further, since the two arc portions of the long diameter portion and the short diameter portion of the gear are connected by a continuous single oval curve, the tangent angles at the connection points B and C of the arc and the oval curve are continuous, Since a non-circular gear having a pitch curve with a small change in angular acceleration and smoothly changing is realized, the inertial force that interacts with the non-circular gear becomes smooth. As a result, the tooth profile is less likely to be locally worn as in the conventional example, which not only increases the durability but also reduces the change in friction torque caused by the increase in the tooth contact pressure. It is possible to realize a volumetric flowmeter having extremely excellent characteristics, such as improved accuracy and stability, and further reduced noise during operation.
Needless to say, if the major axis of the non-circular gear according to the present invention matches the inner diameter of the measuring chamber, the rotor can be replaced with a conventional oval gear rotor.
[0013]
【The invention's effect】
As described above, according to the present invention, the number of gear teeth in contact with the inner wall surface of the measuring chamber can be increased by making the major axis of the pitch curve of the non-circular gear into an arc concentric with the measuring chamber. The amount of leakage in the tooth tip gap can be reduced.
In addition, by connecting the major axis and the minor axis that are concentric with the measuring chamber with a single oval curve, the tangential acceleration changes smoothly, and the teeth unique to the oval gear type flow meter. This can prevent local wear and reduce the adverse effects caused by the pulsation of the measurement fluid.
Then, by using the measuring chamber of the conventional oval gear type flow meter as it is and replacing the used oval gear with the gear of the present invention, it can be changed to a highly accurate flow meter.
[Brief description of the drawings]
FIG. 1 is a view showing a profile of a non-circular gear according to the present invention.
FIG. 2 is a detailed view of the first quadrant of the non-circular gear profile of the present invention.
FIG. 3 is a view showing a conventional oval gear type flow meter.
FIG. 4 is an enlarged view of a clearance between a gear tooth tip and a measuring chamber.
[Explanation of symbols]
DESCRIPTION OF
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16264499A JP3620997B2 (en) | 1999-06-09 | 1999-06-09 | Improvement of non-circular gear and non-circular gear type flow meter using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16264499A JP3620997B2 (en) | 1999-06-09 | 1999-06-09 | Improvement of non-circular gear and non-circular gear type flow meter using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000346689A JP2000346689A (en) | 2000-12-15 |
| JP3620997B2 true JP3620997B2 (en) | 2005-02-16 |
Family
ID=15758549
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16264499A Expired - Fee Related JP3620997B2 (en) | 1999-06-09 | 1999-06-09 | Improvement of non-circular gear and non-circular gear type flow meter using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3620997B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3827655B2 (en) * | 2003-06-24 | 2006-09-27 | 株式会社オーバル | Volumetric flow meter using non-circular gear and non-circular gear |
| JP4203531B1 (en) | 2008-01-24 | 2009-01-07 | 株式会社オーバル | Volumetric flow meter |
| JP4252614B1 (en) * | 2008-03-03 | 2009-04-08 | 株式会社オーバル | Volumetric flow meter and helical gear |
| DE102019122279A1 (en) * | 2019-06-04 | 2020-12-10 | Schaeffler Technologies AG & Co. KG | Connecting element with a connecting part having a thread |
-
1999
- 1999-06-09 JP JP16264499A patent/JP3620997B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000346689A (en) | 2000-12-15 |
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