JP3797566B2 - Evaluation method of pneumatic drive system and cylinder drive pressure measuring device - Google Patents

Description

Ｘ ＝変位
Ａ_d ＝ピストン面積
ｕ ＝速度
式（２）を整理すると、流量は次式のようになる。
Ｗ＝（Ｐ_d ・Ａ_d ／ＲＴ）ｕ …（３）
すなわち、流量Ｗはピストン速度ｕに比例する。Ｗは計算によって求めるから等価流量とする。
【００１６】
また、定常状態における空気圧駆動回路の状態について、等速度駆動で述べたように、駆動回路の流量が一定であれば、構成機器の両端に現われる圧力は流体力学の原理により、各機器の流量特性に比例した圧力差でなければならない。この差圧は直接に機器の流量係数を示し、かつシリンダの推力を表す駆動圧にもつながるから、動作状態の適否を判断できることになる。
ここでは等価流量と差圧の関係から機器の流量特性を作動状態において知ることができ、かつ計算によって求めることができる。差圧の項から理論流量が求められ、これと等価流量から流量係数が計算できる。また、これはＫｓ値で求めた値に等しくなる。
【００１７】
空気圧駆動の実際に定常状態を対比すると、上述は、定常状態において駆動回路と各機器の特性を求めたものである。次に、実際にシリンダで負荷を駆動させた場合の状態を知るには、対比できるように同一の駆動回路で行った実験結果を求めなければならない。この場合、ピストンはストローク端に達するまで、駆動条件によって種々の動作パターンを示すことになる。この場合でも種々のピストン速度を選び、その速度で等速度移動させた定常状態では、各ピストン速度に対応した駆動圧は確定する。前もってこの実験値を求めておけば、実際の駆動状態において変化するピストンの速度に対しても、対応する駆動圧は等速度移動時のそれと一致を示す。
【００１８】
さらに、ピストンの運動の連続性のグラフ表示について、シリンダの動作を解析する場合、ピストンの状態を変位で取り扱うのが一般的であったが、その上述された等速度駆動、定常状態における空気圧駆動回路の状態、および空気圧駆動の実際と定常状態との対比を通じて知れるように、むしろ、駆動圧とピストン速度で表示した方がより具体的情報を提供するように考えられる。定常状態での実験結果によれば駆動圧はピストン速度に対して唯一の値を示すから、ピストンの状態を駆動圧とピストン速度の平面で表示するのが適当である。従って、駆動圧とピストン速度で表した状態（点）を動作点と名付ければ、図２の点Ｍのように示される。ピストン速度は等価流量を表すから、この平面上の点Ｍは、エネルギーを表す。
例えば動作点Ｍが不変であれば、Ｍ−Ｐ_d −Ｏ−ｕで囲まれた面積が供給されるエネルギーを意味する。
一般の作動状態ではピストンはその速度を変化させながら運動をするから、動作点は連続した線で表されることになる。その空気圧駆動の実際と定常状態との対比で述べたようにピストンを特定の等速度で移動すれば、動作点もこれに対応した駆動圧で表される点に移動する。ピストンは連続して運動するわけであるから、実際には連続した動作点の移動、すなわち軌跡になるこれを動作線図と呼ぶ。
【００１９】
またさらに、シリンダ動作点および動作線図とエネルギー表示について、前述されたように、駆動回路の構成機器の選定については、各機器間の圧力（例えばバルブ圧）測定が必要となるが、シリンダの動作という観点から注目すれば、駆動圧がより重要になる。しかし、両者ともピストンの定速度移動という測定方法から同時に得られた結果であり、等価流量の役割も同様である。
さて、そのシリンダ動作点は、特定の動作条件（供給圧と移動速度）の下での測定値であるから、いま供給圧を上（下）げれば、同じ移動速度でも駆動圧は上（下）方に移動する。このことを図示すれば、そのシリンダ動作点は駆動圧−等価流量（ピストン速度）平面の等価流量一定の線上で移動し、図３のように表示される。
また、シリンダが動作点Ｍ１で負荷を駆動した場合のエネルギー供給は図３では
面積（Ｐ_d −Ｍ₁ −Ｕ₁ −Ｏ）
で表される。
次に、同じ供給圧の下でもピストンをより速く移動させると、シリンダ動作点は下方（上方）に移動し、図４に示すように表される。すなわち、ピストンの移動速度を速くすると（Ｕ₂ ＞Ｕ₁ ）、等価流量が大きくなるから、駆動回路の流量特性が同じであれば等価流量の増加分だけ圧力降下（（Ｐ_S −Ｐ_d1）＜（Ｐ_S −Ｐ_d2））が大きくなる。従って、供給できるエネルギーは
面積（Ｐ_d2−Ｍ₂ −Ｕ₂ −Ｏ）
のようになる。
動作線図は前述されたような特徴を持つから、シリンダが作動状態にあればピストンの運動は動作線図の上を移動するものとして理解できる。すなわち、シリンダの動作はピストンが動作線図上のどの範囲を、どのように移動するかとして理解するかという問題になる。このことは、それぞれの瞬間の動作点の座標を定量的に把握すべきであるということになる。そのために、ピストンの移動速度を相当数変化させて求めた動作点の正確な資料を求め、正確な動作線図を作成できるようにしておくことが必要になる。その動作線図の形状については、具体例の説明のところで詳細に述べる。
【００２０】
【具体例の説明】
以下、この発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の特定された具体例について、図面を参照して説明する。図５および図６は、この発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例１０を示している。そのシリンダの駆動圧測定装置１０は、空気圧駆動システム２０に適用され、特に、その評価法を用いて空気圧駆動回路２１の設計に活用されている。そして、そのシリンダの駆動圧測定装置１０は、その空気圧駆動回路２１が方向切換弁２３のみを考慮して簡単化されるので、その空気圧駆動回路２１においてシリンダ２２の駆動圧、すなわち、シリンダ内駆動圧が測定される構成である。さらに具体的には、その空気圧駆動回路２１が空気圧配管２７でそのシリンダ２２に空気圧源２４を接続し、そして、その空気圧配管２７の途中にその方向切換弁２３を配置する構成であるので、そのシリンダの駆動圧測定装置１０では、定速度駆動装置１１がピストン２５のピストン・ロッド２６に連結され、そして、そのシリンダ内駆動圧を測定する圧力センサ１２が準備される。そして、図７はそのシリンダの駆動圧測定装置１０が、その方向切換弁２３を合成流体抵抗２８に置き換えて示されている。
【００２１】
そのようにそのシリンダの駆動圧測定装置１０が構成されるところは、その空気圧駆動システムの評価法がその空気圧駆動回路２１においてそのシリンダ内駆動圧が負荷の下に速度に応じてそのピストン２５の等速度移動で測定され、そして、そのピストン２５の動作点、すなわち、シリンダ動作点の軌跡である動作線図に表されるところにあることから、定常状態での特性の確認はそのピストンを等速度で移動させることにあってそれは駆動機構と駆動圧の測定部とを備える基本構造である。その基本構造は、また、回路を構成する各機器の特性を知る上で活用可能である。
【００２２】
図８は、実際の空気圧駆動システム５０の空気圧駆動回路５１の設計に適用されるこの発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例３０を示し、そして、その空気圧駆動システム５０では、その空気圧駆動回路５１はピストン５５で区画される一対のシリンダ室５３，５４を備えてその一方のシリンダ室５３が空気圧配管６５で空気圧源５７に、その他方のシリンダ室５４が別の空気圧配管６６でその空気圧源５７にそれぞれ接続されるシリンダ５２と、その空気圧配管６５に配置される減圧弁５８、リザーバ５９、ストップ弁６０、および方向切換弁６１と、その空気圧配管６６に配置される減圧弁６２と、その減圧弁６２の下流でその空気圧配管６６から分岐される排気管６７と、その排気管６７に配置される方向切換弁６３および可変絞り弁６４とで構成されている。
【００２３】
そのシリンダの駆動圧測定装置３０は、その空気圧駆動回路５１のそのシリンダ５２に接続される定速度駆動装置３１と、そのシリンダ５２の駆動圧を測定する駆動圧センサ３７と、そのシリンダ５２の背圧を測定する背圧センサ３８と、供給圧センサ３９と、バルブ圧センサ４０とを含み、そして、その定速度駆動装置３１がその空気圧駆動回路５１のそのシリンダ５２に接続される負荷３２と、ベルト駆動で回転されるボール・スクリュー機構３４を用いて等速度でそのシリンダのそのピストン５５を移動させる電動機３３と、そのボール・スクリュー機構３４でベルト駆動されるタコジェネレータ（図示せず）とで構成されてそのピストン５５の等速度移動を確実にしている。
【００２４】
さらに具体的に述べると、その負荷３２がそのピストン５５のピストン・ロッド５６に連結され、また、そのボール・スクリュー機構３４がボール・スクリュー３５およびナット３６で構成されてそのナット３６でその負荷３２に結合されるので、その電動機３３はそのボール・スクリュー３５およびナット３６を介してそのピストン５５の等速度移動を実現する。そのボール・スクリュー３５はベルト駆動でその電動機３３の回転が伝えられ、そしてさらに、そのボール・スクリュー３５はベルト駆動でその回転速度をそのタコジェネレータに伝えて移動速度を検出する構成になっている。
【００２５】
その電動機３３は小型の交流誘導機であるが、等速度回転を維持できるように電気制御回路を使用して調整している。実際には、小型の電動機の出力では供給圧およびピストン移動速度を増加させたときに等速度駆動が困難になるので、適当な背圧を印加したり、また、絞りの調整を併用してその電動機３３にかかる負荷トルクを減少させるようになっている。
その駆動圧はそのシリンダ５２のそのシリンダ室５３内の圧力を直接測定するようにヘッド・カバーを改善してその中にその駆動圧センサ３７は組み込まれる。
その方向切換弁６１は、図６に示すように複雑な流路を形成するので、バルブ出口にはそのバルブ圧センサ４０を取り付けできる継手を使用してその出口の圧力を測定可能にしている。
また、空気圧源５７の圧力がそのピストン５５の移動中にその影響を受けるのを避けるためにそのリザーバ５９を配置して圧力変動を防止する対策がとられている。
【００２６】
そのシリンダの駆動圧測定装置３０による実測結果は図９に示す。この実測では、そのピストン５５の等速度移動に重点を置いているので、速度および駆動圧が同時に安定することを期待している。しかし、記録上の速度は平均的には一定とみなせるが、多分、その電動機３３の回転がそのボール・スクリュー３５および有歯ベルトを介してそのタコジェネレータに伝えられるために、ノイズのような変動が含まれている。恐らくその歯形による影響が表れていると考える。
ここで、その記録からみると、Ｐ_v およびＰ_d は最終的には一定値に落ち着いていると判断される。しかし、一定値に達するまでに僅かに認められる変化の傾向は、制御回路の能力不足が原因と考えられる。この記録は供給圧Ｐ_s ＝２．５ｋｇｆ／ｃｍ² での実測結果を示しているが、Ｐ_d は２．３ｋｇｆ／ｃｍ² の状態を示している。Ｐ_v は２．２ｋｇｆ／ｃｍ² を示しているが、これはセンサ出力の調整不足も含まれているので、修正は必要であり、操作は簡単である。
さらに、等速度移動の大きさを変えるためその電動機３３のギヤー・ヘッドを取り換えて、別の等速度に変更させて行い、その時の駆動圧および速度を正確に測定できれば、違った動作点が得られることになる。動作点が大きく変化すると考えられる高速度での駆動は必要であるが、速度のみについて考えれば、数種の速度からでも連続性を利用して速度の値を確定できる。使用したそのシリンダ５２のストロークは３００ｍｍであるから、ピストン５５の始動から停止までの時間を測定して、大略の速度を計算することもできる。このことは、次に等価流量の精度を高めるために必要であり、その電動機３３の回転速度の制御が重要になってくる。
【００２７】
図１０は、別の実際の空気圧駆動システム９０の空気圧駆動回路９１の設計に適用されるこの発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例７０を示し、そして、その空気圧駆動システム９０では、その空気圧駆動回路９１はピストン９５で区画される一対のシリンダ室９３，９４を備えてその一方のシリンダ室９３が空気圧配管１０５で空気圧源９７に、その他方のシリンダ室９４が別の空気圧配管１０６でその空気圧源９７にそれぞれ接続されるシリンダ９２と、その空気圧配管１０５に配置される減圧弁９８、リザーバ９９、ストップ弁１００、および方向切換弁１０１と、その空気圧配管１０６に配置される減圧弁１０２と、その減圧弁１０２の下流でその空気圧配管１０６に配置される方向切換弁１０３と、その方向切換弁１０３に接続される排気管１０７と、その排気管１０７に配置される可変絞り弁１０４とで構成される。そのように、この空気圧駆動回路９１は、図８に示すその空気圧駆動回路５１において排気側の電磁弁６３が（２／２）の構造から（３／２）の構造の電磁弁１０３に置き換えられている。すなわち、この空気圧駆動回路９１は、方向切換弁（３／２）の２個を使用して負荷を駆動するシリンダの操作回路である。
【００２８】
そのシリンダの駆動圧測定装置７０は、その空気圧駆動回路９１のそのシリンダ９２に接続される定速度駆動装置７１と、そのシリンダ９２の駆動圧を測定する駆動圧センサ７７と、そのシリンダ９２の背圧を測定する背圧センサ７８と、供給圧センサ７９と、バルブ圧センサ８０とを含み、そして、その定速度駆動装置７１がその空気圧駆動回路９１のそのシリンダ９２に接続される負荷７２と、その負荷７２に連結されるボール・スクリュー機構７３でベルト駆動されるタコジェネレータ７６とで構成されている。すなわち、その定速度駆動装置７１は、図８に示すその定速度駆動装置３１においてベルトを外してその電動機３３の作用を除き、単に、そのタコジェネレータ７６にそのピストン９５の移動速度を直接伝えて測定する機構になっている。勿論、その負荷７２はそのピストン９５のピストン・ロッド９６に連結され、また、そのボール・スクリュー機構７３はボール・スクリュー７４およびナット７５で構成されてそのナット７５でその負荷７２に結合される。
【００２９】
そのシリンダの駆動圧測定装置７０による実測結果は図１１、図１２、および図１３に示す。図１１、図１２、および図１３のうち、特に注意しなければならないこととして、図１１はそのピストン９５の動作が背圧の変化に強く影響されていることを示し、駆動圧にはそれほど影響されていないことを示している。ただし、図１１のみは図８に示す回路構成を使用し、その電動機３３をそのタコジェネレータ７６に取り換え、そして、減圧弁１０２の出力をＰ_b ＝２ｋｇｆ／ｃｍ² に設定した状態での結果である。
また、図１２および図１３は共に図１０に示す回路での実測結果である。図１１、図１２、および図１３を通じてそのピストン９５の動作がその速度変化の中に振動現象が含まれるものから単調に増加するものへと変わって行く過程を表している。
【００３０】
特に、この空気圧駆動回路９１には、チューブの長さおよび内径を換えた場合にそのピストン９５の速度を絞り調整によって変化させてバルブ圧、駆動圧、およびピストン速度を求めた。
そのチューブ長さの違うもの３種（５０、１００、１５０ｃｍ）を選び、それぞれの選択基準として排気側の絞り弁１０４の開度をとり、そして、絞りの変化による速度の増加に従って生じる駆動圧の最大低下量と最大等価流量との関係をエネルギー面で表すと図１４、図１５、および図１６のようになる。そのように、そのピストン９５の速度が変化した場合の駆動圧の低下がエネルギー面で把握される。
【００３１】
図１４、図１５、および図１６は、それぞれデータからの読み取り量であるので、計算値に多少のバラツキが認められるが、図示のように直線で近似できる。注目すべきことは図１４、図１５、および図１６における直線がほぼ同一点から出発し、そして、それぞれ違った傾斜角度の直線になっていることである。その傾斜角度の違いはチューブ長さによって生ずる結果であって、さらに、チューブ長さがエネルギー損失の違いになることを表していることを示している。出発点の一致は実質的に降下の表れる速度を示すものと考える。ここで、横軸の速度は実測の速度表示ではなく、記録紙に記録されているスケールを単位にとって、比較換算した等価流量である。
【００３２】
空気圧駆動回路の設計は、シリンダの動作が設定した条件を満たすことを目的に行われるものであるが、計算上の設計ではピストンの速度とシリンダ内駆動圧との関係を明確に示すことはできない。図１１、図１２、および図１３に示す結果からピストンの運動は、背圧の影響を強く受けているが、シリンダ内駆動圧は、それほど強い影響力を与えていないことを示している。これから駆動側にとって重要なことは、ピストンが運動を続けるにはエネルギーの供給が必要であって図１１、図１２、および図１３の結果が示していることは、エネルギー供給の事情とピストンの動作パターンとに分けて検討せねばならぬことを意味している。また、両者は強く結びついているから、ピストンの運動はエネルギー供給に関連させて明らかにできる。それは、シリンダ動作点（ピストンの動作点）とそのシリンダ動作点（ピストンの動作点）の軌跡である動作線図の導入である。
【００３３】
定常状態におけるピストンの動作は、ピストンの移動速度と駆動圧とで特定でき、それは、図１１、図１２、および図１３の結果に基づいて図１７に示すＭ点として表せる。また、ピストンの移動速度を変えて駆動圧の変化を確かめると、動作点Ｍ₁ ，Ｍ₂ は、図１７に示すように特定される。さらに、速度を数多く変えてピストンを等速度で移動させて駆動圧の変化を求めると、動作点が数多く特定されることになって図１７に示す動作線図が得られる。図１１ないし図１６に示す結果、そして、図１７に示すその得られたシリンダの動作点および動作線図から、
ａ．供給圧が一定で駆動回路の合成抵抗が不変のとき、ピストン移動が増加すれば、駆動圧（降下量）が大きくなる、
ｂ．供給圧が一定で等価流量が不変のとき、駆動回路の合成抵抗を大きくすれば、駆動圧（降下量）が大きくなる、
ｃ．供給圧が一定で駆動圧が不変のとき、駆動回路の合成抵抗を大きくすると、等価流量は小さくなる、そして、
ｄ．駆動回路の合成抵抗が不変で等価流量が不変のとき、供給圧を高くすれば、駆動圧は上がるが、降下量が大きくなる
ことが分る。
また、上述に基づいて動作線図をＲ_C1＞Ｒ_C2＞Ｒ_C3のときを作図すると、それらは図１８に示すように駆動回路の合成抵抗によって違うことになる。
【００３４】
さらに、ピストンの運動状態と動作線図について、ピストンの運動は動作点の移動として理解することができるから、動作線図はピストンの運動軌跡そのものである。すなわち、ピストンは動作条件によって動作のパターンに違いがでるけれども、その違いは動作線図上の範囲として特定される。特に、動作線図の形状やエネルギー面での位置は駆動回路の合成抵抗によって違ってくる。このことは機器の選定の問題と直接に関係してくる。
特定の駆動回路での動作線図は唯一として決定され、しかもピストンの動作範囲も規定される。したがって、ピストンおよび負荷を含む運動方程式の解を正確に計算しなくても、図１０に示すその空気圧駆動回路９０で測定結果を資料として所有すれば、動作に関する全ての問題の解が容易に知りうる。そうすると動作線図が駆動回路とシリンダの動作を統一して解明するに有効であり、かつ必要である。
上述からこの方法はエネルギー供給の面から駆動系の動作を解釈するものであり、そして、シリンダ動作点の移動である動作線図による特性評価法が空気圧駆動システムの総合評価に有効であることが知れる。
【００３５】
そのように、空気圧駆動回路の特性を総合的に評価するには、シリンダ動作点および動作線図の利用法が実際に即して有効で有利である。そのシリンダ動作点の導入の効果は、
１．等価流量の計算、ついで
２．駆動回路構成機器の上流、下流側圧力または圧力差の正確な測定、ついで
３．Ｋｓ値法の利用による機器の流量特性の評価、ついで
４．構成用機器の適性な選定、
にあり、その結果として動作点を利用すれば、
１．設計回路による実体駆動回路の静的特性の確認、ついで
２．同上の動作状態の定量的確認
にあり、そのシリンダ動作点は特定の供給圧力でシリンダを駆動する場合の、しかも定常状態におけるピストン速度とシリンダ内駆動圧から一義的に決定されるから、ピストン速度−駆動圧平面上の点として表示できる。また、動作線図導入の効果は、
１．ピストン速度の変化に応じた駆動圧変化のグラフ化（動作線図）、ついで
２．ピストンの動作と動作線図の対応（形状とピストンの動作範囲）、ついで
３．シリンダ動作点の動作線図上の移動とエネルギーの計算
にあり、空気圧駆動回路の設計とシリンダの動作に関する研究が、相互に関連のない状態で進められてきたけれど、ここで空気圧駆動システムとして総合的に理解されたことになる。
【００３６】
先に図面を参照して説明されたところのこの発明の特定された具体例から明らかであるように、この発明の属する技術の分野における通常の知識を有する者にとって、この発明の内容は、その発明の性質（ｎａｔｕｒｅ）および本質（ｓｕｂｓｔａｎｃｅ）に由来し、そして、それらを内在させると客観的に認められる別の態様に容易に具体化される。勿論、この発明の内容は、その発明の課題に相応し（ｂｅ ｃｏｍｍｅｎｓｕｒａｔｅ ｗｉｔｈ）、そして、その発明の成立に必須である。
【００３７】
【発明の便益】
上述から理解されるように、この発明の空気圧駆動システムの評価法は、シリンダ定常状態で空気圧駆動回路のシリンダ内駆動圧を測定し、その駆動からシリンダ動作点を求め、そして、そのシリンダ動作点の軌跡を動作線図に図的に表してその動作線図を活用するので、この発明の空気圧駆動システムの評価法では、シリンダの動作および空気圧駆動回路の特性がそのシリンダ動作点および動作線図で理解されて評価され、そして、その空気圧駆動回路が実態に即して仕様通りに設計可能になり、すなわち、空気圧駆動システムが仕様通りに設計可能になり、その結果、空気圧駆動回路、空気圧駆動システムの設計に非常に有用で実用的である。
【００３８】
また、この発明のシリンダの駆動圧測定装置は、空気圧駆動回路のシリンダに接続される定速度駆動装置と、そのシリンダ内の駆動圧を検出する圧力センサとを含むので、この発明のシリンダの駆動圧測定装置では、そのシリンダ内駆動圧がシリンダ定常状態で測定され、そのシリンダの動作および空気圧駆動回路の特性の理解および評価に用いるシリンダ動作点および動作線図が求められて空気圧駆動システムの評価法が、活用可能になり、そして、その空気圧駆動回路が、実態に即して仕様通りに設計可能になり、すなわち、空気圧駆動システムが、仕様通りに設計可能になり、その結果、空気圧駆動回路、空気圧駆動システムの設計に非常に有用で実用的である。
【図面の簡単な説明】
【図１】この発明の空気圧駆動システムの評価法を示した概念図である。
【図２】空気圧駆動回路を構成する各機器の圧力降下を示したグラフである。
【図３】動作状態シフトに関する供給圧を示したグラフである。
【図４】ピストン速度に対応する動作状態シフトを示したグラフである。
【図５】この発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例を示した概説図である。
【図６】図５に示された方向切換弁の断面図である。
【図７】図５に示された方向切換弁を合成流体抵抗に置き換えたところのその空気圧駆動システムの評価法およびシリンダの駆動圧測定装置を示す概説図である。
【図８】この発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例を示した概説図である。
【図９】図８の駆動圧測定装置で得られた等価流量を示したグラフである。
【図１０】この発明の空気圧駆動システムの評価法およびシリンダの駆動圧測定装置の具体例を示した概説図である。
【図１１】図１０の駆動圧測定装置のピストン動作中に得られた駆動圧を示したグラフである。
【図１２】図１０の駆動圧測定装置がシリンダ状態を変えてピストンの動作中に得られたシリンダ内駆動圧を示したグラフである。
【図１３】図１０の駆動圧測定装置がシリンダ状態をさらに変えてピストンの動作中に得られたシリンダ内駆動圧を示したグラフである。
【図１４】チューブ長さの影響によるエネルギー損失特性を示したグラフである。
【図１５】チューブ長さの影響によるエネルギー損失特性を示したグラフである。
【図１６】チューブ長さの影響によるエネルギー損失特性を示したグラフである。
【図１７】動作状態から描かれた動作線図を示したグラフである。
【図１８】合成抵抗の違いから描かれた動作線図を示したグラフである。
【符号の説明】
１１ 定速度駆動装置
１２ 圧力センサ
２０ 空気圧駆動システム
２１ 空気圧駆動回路
２２ シリンダ
２３ 方向切換弁
２４ 空気圧源
２５ ピストン
２６ ピストン・ロッド
２７ 空気圧配管
２８ 合成流体抵抗[0001]
[Field of Invention]
The present invention relates to a method for evaluating a pneumatic drive system and a cylinder driving pressure measuring device utilized in designing a pneumatic drive circuit so that the operation of a piston in a pneumatic cylinder can be realized as specified.
[0002]
[Background]
Usually, the pneumatic drive circuit is designed so that the piston of the pneumatic cylinder is operated according to specifications, and the configuration of the circuit and the selection of equipment are performed. Therefore, the configuration of the drive circuit and the selection of equipment are important design issues. The structure of the drive circuit employs a standardized structure based on experience so far, and the effective area method is generally used for selecting the device. In addition, the state of the drive circuit will be studied from the relationship between the combined effective sectional area by the sizing method and the assumed flow rate.
[0003]
However, even if a drive circuit as designed can be configured, it does not always operate as expected when the cylinder is actually driven. If the speed control of the cylinder is correctly performed, there may be no problem, but in reality, only the result of not operating as prescribed remains. Knowing how the piston moves and how the result is related to its drive circuit is still good but not clear at all. That is, it is a known fact that the operation when the cylinder is driven is not a constant speed, and the driving pressure is considerably different from the designed value. From such a situation, the design method of the pneumatic drive circuit is not limited to those methods, and a design method more suitable for the actual situation is desired.
[0004]
[Problems of the Invention]
An object of the present invention is to provide a method for evaluating a pneumatic driving system and a cylinder driving pressure measuring device that allow a pneumatic driving circuit to be designed according to specifications in accordance with specifications.
[0005]
[Means corresponding to the problem and its operation]
The present invention measures the in-cylinder driving pressure of the pneumatic driving circuit in a steady state of the cylinder, obtains the cylinder operating point from the driving pressure, graphically represents the locus of the cylinder operating point on the operation diagram, and the operation The pneumatic drive circuit is evaluated with a diagram, and the pneumatic drive system can be designed according to the specifications. The cylinder steady state is a state where the piston is driven at a constant speed, that is, a state where the energy conversion efficiency is maximized, and the piston of the cylinder is moved at a constant speed according to the speed under a load.
The cylinder operating point is represented by the driving pressure and the piston speed.
[0006]
The present invention also includes a constant speed drive connected to the cylinder of the pneumatic drive circuit and a pressure sensor for detecting the drive pressure in the cylinder, the in-cylinder drive pressure is measured in a steady state of the cylinder, and The in-cylinder driving pressure can be utilized in an evaluation method of a pneumatic driving system that evaluates a pneumatic driving circuit with a cylinder operating point and an operation diagram.
[0007]
The present invention provides a method and apparatus for evaluating the operation of a pneumatic drive system in a unified manner with respect to the problem, and using an operation diagram. In the research and development, the operation of the piston can be divided into a steady state and a normal driving state by applying its operation diagram and operation point, and the substance of the operation can be verified. At the time of design, it shows that it is possible to present the suitability of equipment selection by actually measuring the operation of the cylinder, and to quantitatively determine the operation of the piston until the end. Furthermore, it is possible to display the amount of supplied energy and the amount of lost energy from the operation pattern, and it is possible to evaluate the validity of the device selection with respect to the efficiency from the meaning of movement of the display position of the operation diagram.
[0008]
In the present invention, the basis for correctly recognizing pneumatic driving is that the piston is driven at a constant speed as a standard state. The reason is based on the fact that the energy conversion efficiency is maximized in that state. And the pressure which each apparatus shows correctly represents a state value at the time of constant speed drive, and the state is implement | achieved simultaneously by introduce | transducing the method of moving a piston at constant speed.
[0009]
When it is realized that the piston moves at a constant speed, the driving pressure of the cylinder shows a specific value and is constant. At the same time, the pressure generated at both ends of each device also shows a constant value. As long as the piston moves at a constant speed, these values are constant and are considered to be in a steady state. Here, let's focus on the driving pressure. This is because it directly indicates the state value of the cylinder and is unique corresponding to the speed of the piston. From this, the state of the piston is expressed by the driving pressure and the speed of the piston. A point indicating this state is named a cylinder operating point.
[0010]
Since the cylinder operating point in this state indicates that the piston moves at a constant speed, the flow rate flowing into the cylinder at this time can be obtained equivalently by calculation. Therefore, the steady state characteristics of the pneumatic drive circuit can be evaluated by the drive pressure and the flow rate.
[0011]
As described above, from the position coordinates of the cylinder operating point, the supplied energy can be evaluated by the size of the area created by the cylinder operating point. Furthermore, when the speed of the piston fluctuates, the driving pressure changes according to the speed, so that the cylinder operating point also moves. If the trajectory of the moving cylinder operating point is named an operation diagram, it is known that the cylinder characteristic can be quantitatively evaluated by calibrating the characteristics of the cylinder with actual measurement data in a steady state.
[0012]
As such, the cylinder operating point (piston operating point) is uniquely determined with respect to the piston speed, and the change in driving pressure can be explained hydrodynamically. That is, it can be explained that the driving pressure is changed from the pressure of the air pressure source. Further, the operation diagram (operation curve) is a locus of the cylinder operation point, and the operation point descends and changes as the piston speed increases, so that the amount of change can be explained hydrodynamically. That is, the change in the operation diagram is determined by the ratio between the pressure of the air pressure source and the driving pressure that changes according to the piston speed together with the operating point. Of course, the shape of the operation diagram depends on the flow characteristics of the devices constituting the drive circuit. The point that is obtained by measuring the operating point in a steady state is that the driving pressure can be clearly fixed by actually measuring the piston speed under known conditions, and this leads to a place where this can be quantitatively evaluated as a reference point. It is in.
[0013]
The evaluation method of the present invention using these characteristics is based not only on the fact that the drive circuit can be explained qualitatively, but also on a quantitative basis and not inconsistent with the principle. If the characteristics of the drive circuit at a certain design stage evaluated by the operation diagram are not sufficient, it is a matter of course that the equipment will be selected again, but in that case, the operation diagram may be moved up and down or left and right. Appears as a change in shape. Then, the selection of the device, that is, the so-called conversion is effective in the up-and-down movement, and the ineffective range is the left-right movement, particularly the left-hand movement. In addition, obtaining a large number of operating points accurately increases the accuracy of evaluation.
[0014]
Further, the basics of pneumatic driving will be described in detail. When driving a load with a pneumatic cylinder, we have experienced different behavior from the pattern set based on the nature of the load and the operating conditions. In reality, there is a method to clarify the characteristics of the cylinder from the comprehensive judgment of the actual measurement results carried out under various conditions, but this invention is elucidated based on the operation pattern actually measured under the standard setting conditions. The method is developed and developed as a general method, and its concept is described.
[0015]
As for the constant speed drive, it is difficult to actually realize the constant speed drive of the piston. Therefore, as shown in FIG. 1, the constant speed movement of the piston is performed by an external force to realize a steady state.
If the piston moves at a constant speed, the volume increase rate (equivalent flow rate) of the cylinder is constant, and the flow rate flowing through the drive circuit in this volume is balanced, and the pressure in the volume is stabilized. At that time, the pressure in the volume (driving pressure) maintains a constant value, so it is considered that the equivalent flow rate is the same as the flow rate. This is the reason for assuming that the volume increase rate is equivalent to the flow rate. The flow rate at this time is
P _d V = GRT (1)
Where P _d = Drive pressure (constant)
R = gas constant (constant)
T = gas temperature (constant)
G = weight of air pressure in volume
Ask from. Differentiating the above equation

X = displacement
A _d = Piston area
u = speed
When formula (2) is arranged, the flow rate is as follows.
W = (P _d ・ A _d / RT) u (3)
That is, the flow rate W is proportional to the piston speed u. Since W is obtained by calculation, it is an equivalent flow rate.
[0016]
In addition, as described in the constant speed drive for the state of the pneumatic drive circuit in the steady state, if the flow rate of the drive circuit is constant, the pressure appearing at both ends of the component equipment is determined by the flow dynamics The pressure difference must be proportional to This differential pressure directly indicates the flow coefficient of the device and also leads to the driving pressure that represents the thrust of the cylinder, so that the suitability of the operating state can be determined.
Here, the flow characteristics of the device can be known in the operating state from the relationship between the equivalent flow rate and the differential pressure, and can be obtained by calculation. The theoretical flow rate is obtained from the differential pressure term, and the flow rate coefficient can be calculated from this and the equivalent flow rate. This is also equal to the value obtained from the Ks value.
[0017]
When the steady state is actually compared with the pneumatic drive, the above description is for the characteristics of the drive circuit and each device in the steady state. Next, in order to know the state when the load is actually driven by the cylinder, it is necessary to obtain the result of an experiment performed by the same drive circuit so that the comparison can be made. In this case, the piston exhibits various operation patterns depending on the driving conditions until reaching the stroke end. Even in this case, in a steady state in which various piston speeds are selected and moved at the same speed, the driving pressure corresponding to each piston speed is determined. If this experimental value is obtained in advance, the corresponding driving pressure corresponds to that at the time of constant speed movement even for the piston speed changing in the actual driving state.
[0018]
Furthermore, regarding the graph display of piston motion continuity, when analyzing the cylinder motion, it was common to handle the piston state by displacement, but the above-mentioned constant velocity drive, pneumatic drive in the steady state described above Rather, it is thought that the display by the driving pressure and the piston speed provides more specific information as known through the circuit state and the comparison between the actual and steady state of the pneumatic drive. According to the experimental results in the steady state, the driving pressure shows a unique value with respect to the piston speed, so it is appropriate to display the piston state in the plane of the driving pressure and the piston speed. Therefore, if the state (point) represented by the driving pressure and the piston speed is named an operating point, it is shown as a point M in FIG. Since the piston speed represents the equivalent flow rate, the point M on this plane represents energy.
For example, if the operating point M is unchanged, M−P _d The area enclosed by -O-u means the energy supplied.
In a general operating state, the piston moves while changing its speed, so the operating point is represented by a continuous line. If the piston is moved at a specific constant speed as described in comparison between the actual pneumatic driving and the steady state, the operating point is also moved to a point represented by the corresponding driving pressure. Since the piston moves continuously, the movement of the continuous operating point, that is, the locus, is actually called an operation diagram.
[0019]
Furthermore, regarding the cylinder operating point, operation diagram, and energy display, as described above, the selection of the components constituting the drive circuit requires measurement of pressure (for example, valve pressure) between the devices. From the viewpoint of operation, the driving pressure becomes more important. However, both are results obtained simultaneously from the measurement method of constant speed movement of the piston, and the role of the equivalent flow rate is also the same.
Now, the cylinder operating point is a measured value under specific operating conditions (supply pressure and moving speed), so if the supply pressure is increased (lowered), the driving pressure will increase ( Move down). If this is illustrated, the cylinder operating point moves on a line of constant equivalent flow rate in the plane of drive pressure-equivalent flow rate (piston speed), and is displayed as shown in FIG.
The energy supply when the cylinder drives the load at the operating point M1 is shown in FIG.
Area (P _d -M ₁ -U ₁ -O)
It is represented by
Next, when the piston is moved faster even under the same supply pressure, the cylinder operating point moves downward (upward) and is represented as shown in FIG. That is, when the moving speed of the piston is increased (U ₂ > U ₁ ) Since the equivalent flow rate increases, if the flow rate characteristics of the drive circuit are the same, the pressure drop ((P _S -P _d1 ) <(P _S -P _d2 )) Becomes larger. Therefore, the energy that can be supplied is
Area (P _d2 -M ₂ -U ₂ -O)
become that way.
Since the operation diagram has the characteristics as described above, it can be understood that the movement of the piston moves on the operation diagram when the cylinder is in an operating state. That is, the operation of the cylinder becomes a problem of understanding which range and how the piston moves on the operation diagram. This means that the coordinates of the operating point at each moment should be grasped quantitatively. Therefore, it is necessary to obtain accurate data of the operating point obtained by changing the moving speed of the piston by a considerable number so that an accurate operation diagram can be created. The shape of the operation diagram will be described in detail in the description of the specific example.
[0020]
[Explanation of specific examples]
Hereinafter, a specific example of a method for evaluating a pneumatic driving system and a cylinder driving pressure measuring device according to the present invention will be described with reference to the drawings. 5 and 6 show a specific example 10 of the evaluation method of the pneumatic driving system and the cylinder driving pressure measuring device of the present invention. The cylinder driving pressure measuring device 10 is applied to a pneumatic driving system 20, and in particular, is used for designing the pneumatic driving circuit 21 using the evaluation method. The cylinder driving pressure measuring device 10 is simplified in consideration of only the direction switching valve 23 in the pneumatic driving circuit 21. Therefore, in the pneumatic driving circuit 21, the driving pressure of the cylinder 22, that is, in-cylinder driving. The pressure is measured. More specifically, the pneumatic drive circuit 21 is configured to connect the pneumatic source 24 to the cylinder 22 by the pneumatic piping 27 and to arrange the direction switching valve 23 in the middle of the pneumatic piping 27. In the cylinder driving pressure measuring device 10, a constant speed driving device 11 is connected to a piston rod 26 of a piston 25, and a pressure sensor 12 for measuring the in-cylinder driving pressure is prepared. FIG. 7 shows the cylinder driving pressure measuring device 10 in which the direction switching valve 23 is replaced with a synthetic fluid resistance 28.
[0021]
The cylinder driving pressure measuring device 10 is configured in such a manner that the pneumatic driving system is evaluated in accordance with the speed of the piston 25 depending on the speed of the driving pressure in the cylinder in the pneumatic driving circuit 21 under the load. Since it is measured by moving at a constant speed and is shown in the operation diagram of the operating point of the piston 25, that is, the locus of the cylinder operating point, the characteristics of the piston in the steady state can be confirmed. In moving at a speed, it is a basic structure including a driving mechanism and a driving pressure measuring unit. The basic structure can also be used to know the characteristics of each device constituting the circuit.
[0022]
FIG. 8 shows a practical example 30 of the pneumatic driving system evaluation method and cylinder driving pressure measuring device of the present invention applied to the design of the pneumatic driving circuit 51 of the actual pneumatic driving system 50, and the pneumatic driving system. 50, the pneumatic drive circuit 51 includes a pair of cylinder chambers 53, 54 defined by a piston 55, one cylinder chamber 53 serving as a pneumatic source 57 via a pneumatic pipe 65, and the other cylinder chamber 54 serving as another. A cylinder 52 connected to the air pressure source 57 by a pneumatic pipe 66, a pressure reducing valve 58, a reservoir 59, a stop valve 60, and a direction switching valve 61 arranged in the pneumatic pipe 65, and a pneumatic pipe 66. A pressure reducing valve 62, an exhaust pipe 67 branched from the pneumatic piping 66 downstream of the pressure reducing valve 62, and an exhaust pipe 67. Is composed of a directional control valve 63 and the variable throttle valve 64 is.
[0023]
The cylinder driving pressure measuring device 30 includes a constant speed driving device 31 connected to the cylinder 52 of the pneumatic driving circuit 51, a driving pressure sensor 37 for measuring the driving pressure of the cylinder 52, and a back of the cylinder 52. A load 32 including a back pressure sensor 38 for measuring pressure, a supply pressure sensor 39, and a valve pressure sensor 40, and the constant speed drive 31 of which is connected to the cylinder 52 of the pneumatic drive circuit 51; An electric motor 33 that moves the piston 55 of the cylinder at a constant speed using a ball and screw mechanism 34 that is rotated by belt driving, and a tachometer (not shown) that is belt driven by the ball and screw mechanism 34. Thus, the piston 55 is moved at a constant speed.
[0024]
More specifically, the load 32 is connected to the piston rod 56 of the piston 55, and the ball screw mechanism 34 is constituted by a ball screw 35 and a nut 36, and the load 32 is formed by the nut 36. Therefore, the electric motor 33 realizes the constant speed movement of the piston 55 via the ball screw 35 and the nut 36. The ball screw 35 is configured to transmit the rotation of the electric motor 33 by belt driving, and the ball screw 35 is configured to detect the moving speed by transmitting the rotation speed to the tachometer by belt driving. .
[0025]
The electric motor 33 is a small AC induction machine, but is adjusted using an electric control circuit so as to maintain constant speed rotation. Actually, it is difficult to drive at a constant speed when the supply pressure and the piston moving speed are increased with the output of a small electric motor, so it is necessary to apply an appropriate back pressure or adjust the throttle together. The load torque applied to the electric motor 33 is reduced.
The drive pressure improves the head cover to directly measure the pressure in the cylinder chamber 53 of the cylinder 52, and the drive pressure sensor 37 is incorporated therein.
Since the direction switching valve 61 forms a complicated flow path as shown in FIG. 6, the outlet pressure can be measured using a joint to which the valve pressure sensor 40 can be attached.
In order to prevent the pressure of the air pressure source 57 from being affected during the movement of the piston 55, a measure is taken to prevent pressure fluctuation by arranging the reservoir 59.
[0026]
The actual measurement result of the cylinder driving pressure measuring device 30 is shown in FIG. In this actual measurement, since the emphasis is placed on the constant speed movement of the piston 55, it is expected that the speed and the driving pressure are stabilized at the same time. However, although the recording speed can be considered to be constant on average, it is likely that the rotation of the electric motor 33 is transmitted to the tachometer via the ball screw 35 and the toothed belt, so that fluctuations such as noise occur. It is included. Perhaps the influence of the tooth profile appears.
Here, from the record, P _v And P _d Is finally determined to have settled to a certain value. However, the tendency of the change slightly recognized until reaching a certain value is considered to be caused by the insufficient capacity of the control circuit. This record is the supply pressure P _s = 2.5kgf / cm ² Shows the actual measurement result at P _d Is 2.3 kgf / cm ² Shows the state. P _v Is 2.2kgf / cm ² However, this also includes insufficient adjustment of the sensor output, so correction is necessary and the operation is simple.
Furthermore, if the gear head of the motor 33 is changed and changed to another constant speed in order to change the magnitude of the constant speed movement, a different operating point can be obtained if the driving pressure and speed at that time can be accurately measured. Will be. Driving at a high speed where the operating point is considered to change greatly is necessary, but if only the speed is considered, the value of the speed can be determined using continuity even from several speeds. Since the stroke of the cylinder 52 used is 300 mm, the approximate speed can be calculated by measuring the time from the start to the stop of the piston 55. This is next necessary to increase the accuracy of the equivalent flow rate, and control of the rotational speed of the electric motor 33 becomes important.
[0027]
FIG. 10 shows an embodiment 70 of the pneumatic drive system evaluation method and cylinder drive pressure measuring device of the present invention applied to the design of the pneumatic drive circuit 91 of another actual pneumatic drive system 90, and its pneumatic pressure. In the drive system 90, the pneumatic drive circuit 91 includes a pair of cylinder chambers 93 and 94 defined by a piston 95, one cylinder chamber 93 serving as a pneumatic source 97 through a pneumatic pipe 105, and the other cylinder chamber 94 serving as a cylinder chamber 94. A cylinder 92 connected to the air pressure source 97 by another air pressure pipe 106, a pressure reducing valve 98, a reservoir 99, a stop valve 100, and a direction switching valve 101 disposed in the air pressure pipe 105, and the air pressure pipe 106 The pressure reducing valve 102 arranged, and the direction switching valve 1 arranged in the pneumatic piping 106 downstream of the pressure reducing valve 102 3, composed of an exhaust pipe 107 connected to the directional control valve 103, a variable throttle valve 104 disposed in the exhaust pipe 107. As described above, in this pneumatic drive circuit 91, in the pneumatic drive circuit 51 shown in FIG. 8, the solenoid valve 63 on the exhaust side is replaced with the solenoid valve 103 having the (3/2) structure from the (2/2) structure. ing. That is, the pneumatic drive circuit 91 is a cylinder operation circuit that drives a load using two of the direction switching valves (3/2).
[0028]
The cylinder driving pressure measuring device 70 includes a constant speed driving device 71 connected to the cylinder 92 of the pneumatic driving circuit 91, a driving pressure sensor 77 for measuring the driving pressure of the cylinder 92, and a back of the cylinder 92. A load 72 including a back pressure sensor 78 for measuring pressure, a supply pressure sensor 79, and a valve pressure sensor 80, the constant speed drive 71 of which is connected to the cylinder 92 of the pneumatic drive circuit 91; It comprises a tacho generator 76 that is belt-driven by a ball and screw mechanism 73 connected to the load 72. That is, the constant speed driving device 71 removes the belt from the constant speed driving device 31 shown in FIG. 8 and removes the action of the electric motor 33, and simply directly transmits the moving speed of the piston 95 to the tachometer 76. It is a mechanism to measure. Of course, the load 72 is connected to the piston rod 96 of the piston 95, and the ball screw mechanism 73 is composed of a ball screw 74 and a nut 75, and is coupled to the load 72 by the nut 75.
[0029]
The actual measurement results by the cylinder driving pressure measuring device 70 are shown in FIGS. 11, 12, and 13. FIG. 11, 12, and 13, it should be particularly noted that FIG. 11 shows that the operation of the piston 95 is strongly influenced by the change in the back pressure, and the driving pressure has a great influence. It has not been shown. However, only FIG. 11 uses the circuit configuration shown in FIG. 8, the electric motor 33 is replaced with the tacho generator 76, and the output of the pressure reducing valve 102 is changed to P _b = 2kgf / cm ² It is a result in the state set to.
12 and 13 are both actual measurement results in the circuit shown in FIG. 11, 12, and 13 illustrate a process in which the operation of the piston 95 changes from the one in which the vibration phenomenon is included in the speed change to the one that increases monotonously.
[0030]
In particular, in the pneumatic drive circuit 91, the valve pressure, the drive pressure, and the piston speed were obtained by changing the speed of the piston 95 by adjusting the throttle when the length and the inner diameter of the tube were changed.
Three types (50, 100, 150 cm) with different tube lengths are selected, and the opening of the throttle valve 104 on the exhaust side is taken as the selection criterion, and the driving pressure generated as the speed increases due to the change in the throttle is selected. The relationship between the maximum reduction amount and the maximum equivalent flow rate is expressed in terms of energy as shown in FIG. 14, FIG. 15, and FIG. As such, the decrease in driving pressure when the speed of the piston 95 changes is grasped in terms of energy.
[0031]
14, 15, and 16 are read amounts from data, respectively, and there are some variations in the calculated values, but they can be approximated by a straight line as shown. It should be noted that the straight lines in FIGS. 14, 15, and 16 start from substantially the same point, and are straight lines with different inclination angles. The difference in inclination angle is a result caused by the tube length, and further indicates that the tube length represents a difference in energy loss. The coincidence of the starting points is considered to indicate the speed at which the descent appears. Here, the speed on the horizontal axis is not an actual speed display, but an equivalent flow rate that is comparatively converted with the scale recorded on the recording paper as a unit.
[0032]
The design of the pneumatic drive circuit is performed for the purpose of satisfying the set conditions of the cylinder operation. However, the calculation design cannot clearly show the relationship between the piston speed and the drive pressure in the cylinder. . From the results shown in FIGS. 11, 12, and 13, it is shown that the piston motion is strongly influenced by the back pressure, but the in-cylinder driving pressure is not so strongly influenced. What is important for the drive side is that energy supply is necessary for the piston to continue its movement, and the results shown in FIGS. 11, 12, and 13 show that the situation of energy supply and the operation of the piston This means that it must be divided into patterns. Also, since the two are strongly connected, the piston movement can be revealed in relation to the energy supply. It is the introduction of a cylinder operating point (piston operating point) and an operating diagram that is the locus of the cylinder operating point (piston operating point).
[0033]
The operation of the piston in the steady state can be specified by the moving speed of the piston and the driving pressure, which can be expressed as point M shown in FIG. 17 based on the results of FIGS. 11, 12, and 13. Also, when the change in the driving pressure is confirmed by changing the moving speed of the piston, the operating point M ₁ , M ₂ Is specified as shown in FIG. Furthermore, when the speed is changed and the piston is moved at a constant speed to determine the change in the driving pressure, many operating points are specified, and the operation diagram shown in FIG. 17 is obtained. From the results shown in FIGS. 11 to 16 and the operating point and operating diagram of the obtained cylinder shown in FIG.
a. When the supply pressure is constant and the combined resistance of the drive circuit is unchanged, if the piston movement increases, the drive pressure (drop amount) increases.
b. When the supply pressure is constant and the equivalent flow rate is unchanged, increasing the combined resistance of the drive circuit will increase the drive pressure (drop amount).
c. When the supply pressure is constant and the drive pressure is unchanged, increasing the combined resistance of the drive circuit reduces the equivalent flow rate, and
d. When the combined resistance of the drive circuit is unchanged and the equivalent flow rate is unchanged, increasing the supply pressure increases the drive pressure but increases the amount of descent
I understand that.
In addition, based on the above, the operation diagram is R _C1 > R _C2 > R _C3 When drawing the above, they differ depending on the combined resistance of the drive circuit as shown in FIG.
[0034]
Furthermore, with regard to the movement state and operation diagram of the piston, since the movement of the piston can be understood as the movement of the operation point, the operation diagram is the movement locus of the piston itself. That is, although the piston has different movement patterns depending on the operation conditions, the difference is specified as a range on the operation diagram. In particular, the shape of the operation diagram and the position in terms of energy vary depending on the combined resistance of the drive circuit. This is directly related to the problem of equipment selection.
The operating diagram for a particular drive circuit is determined as unique and also defines the operating range of the piston. Therefore, even if the solution of the equation of motion including the piston and the load is not accurately calculated, if the measurement result is possessed as data by the pneumatic drive circuit 90 shown in FIG. sell. Then, the operation diagram is effective and necessary to unify the operation of the drive circuit and the cylinder.
From the above, this method interprets the operation of the drive system from the aspect of energy supply, and the characteristic evaluation method based on the operation diagram that is the movement of the cylinder operating point is effective for comprehensive evaluation of the pneumatic drive system. I know.
[0035]
As described above, in order to comprehensively evaluate the characteristics of the pneumatic drive circuit, it is effective and advantageous to use the cylinder operating point and the operating diagram in practice. The effect of introducing the cylinder operating point is
1. Equivalent flow calculation, then
2. Accurate measurement of upstream or downstream pressure or pressure difference of drive circuit components, then
3. Evaluation of flow rate characteristics of equipment by using Ks value method
4). Appropriate selection of configuration equipment,
If you use the operating point as a result,
1. Confirmation of static characteristics of actual drive circuit by design circuit,
2. Quantitative confirmation of operating status
The cylinder operating point is uniquely determined from the piston speed in the steady state and the in-cylinder driving pressure when the cylinder is driven with a specific supply pressure. Can be displayed. The effect of introducing the operation diagram is
1. Graph of driving pressure change according to piston speed change (operation diagram), then
2. Correspondence between piston movement and operation diagram (shape and piston operating range),
3. Movement of cylinder operating point on the operation diagram and calculation of energy
However, research on the design of pneumatic drive circuits and the operation of cylinders has been conducted in an unrelated manner, but here it has been comprehensively understood as a pneumatic drive system.
[0036]
As will be apparent from the specific embodiments of the present invention described above with reference to the drawings, for those of ordinary skill in the art to which the present invention pertains, It is easily embodied in another embodiment that derives from the nature and the nature of the invention and is objectively recognized as having them inherent. Of course, the content of this invention corresponds to the problem of the invention (be recommend with) and is essential for the establishment of the invention.
[0037]
[Benefits of the invention]
As understood from the above description, the pneumatic drive system evaluation method of the present invention measures the in-cylinder drive pressure of the pneumatic drive circuit in the steady state of the cylinder, obtains the cylinder operating point from the drive, and the cylinder operating point. In the method of evaluating the pneumatic drive system according to the present invention, the cylinder operation and the characteristics of the pneumatic drive circuit are related to the cylinder operation point and the operation diagram. And the pneumatic drive circuit can be designed to the specifications according to the actual situation, that is, the pneumatic drive system can be designed to the specifications, so that the pneumatic drive circuit, the pneumatic drive Very useful and practical for system design.
[0038]
The cylinder driving pressure measuring device of the present invention includes a constant speed driving device connected to the cylinder of the pneumatic driving circuit and a pressure sensor for detecting the driving pressure in the cylinder. In the pressure measuring device, the in-cylinder driving pressure is measured in a steady state of the cylinder, and the cylinder operating point and operation diagram used for understanding and evaluating the characteristics of the cylinder operation and the pneumatic driving circuit are obtained to evaluate the pneumatic driving system. And the pneumatic drive circuit can be designed according to the specifications according to the actual situation, that is, the pneumatic drive system can be designed according to the specifications, and as a result, the pneumatic drive circuit Very useful and practical in the design of pneumatic drive systems.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an evaluation method of a pneumatic drive system of the present invention.
FIG. 2 is a graph showing a pressure drop of each device constituting the pneumatic drive circuit.
FIG. 3 is a graph showing a supply pressure related to an operation state shift.
FIG. 4 is a graph showing an operation state shift corresponding to the piston speed.
FIG. 5 is a schematic diagram showing a specific example of an evaluation method for a pneumatic drive system and a cylinder drive pressure measuring device according to the present invention.
6 is a cross-sectional view of the direction switching valve shown in FIG.
7 is a schematic diagram showing an evaluation method of the pneumatic drive system and a cylinder drive pressure measuring device in which the directional control valve shown in FIG. 5 is replaced with a synthetic fluid resistance.
FIG. 8 is a schematic diagram showing a specific example of a pneumatic driving system evaluation method and a cylinder driving pressure measuring device according to the present invention.
9 is a graph showing an equivalent flow rate obtained by the driving pressure measuring device of FIG.
FIG. 10 is a schematic diagram showing a specific example of an evaluation method of a pneumatic drive system and a cylinder drive pressure measuring device according to the present invention.
11 is a graph showing driving pressure obtained during piston operation of the driving pressure measuring device of FIG. 10;
12 is a graph showing in-cylinder driving pressure obtained during operation of the piston by the driving pressure measuring device of FIG. 10 changing the cylinder state.
13 is a graph showing in-cylinder driving pressure obtained during the operation of the piston by further changing the cylinder state in the driving pressure measuring device of FIG.
FIG. 14 is a graph showing energy loss characteristics due to the influence of the tube length.
FIG. 15 is a graph showing energy loss characteristics due to the influence of the tube length.
FIG. 16 is a graph showing energy loss characteristics due to the influence of the tube length.
FIG. 17 is a graph showing an operation diagram drawn from an operation state.
FIG. 18 is a graph showing an operation diagram drawn from a difference in combined resistance.
[Explanation of symbols]
11 Constant speed drive
12 Pressure sensor
20 Pneumatic drive system
21 Pneumatic drive circuit
22 cylinders
23 Directional switching valve
24 Air pressure source
25 piston
26 Piston rod
27 Pneumatic piping
28 Synthetic fluid resistance

Claims (3)

  The cylinder drive pressure of the pneumatic drive circuit is measured in the steady state of the cylinder, the cylinder operating point is obtained from the drive pressure, and the locus of the cylinder operating point is graphically represented in the operation diagram and utilized. Evaluation method of pneumatic drive system.   The method for evaluating a pneumatic drive system according to claim 1, wherein the steady state of the cylinder moves the piston of the cylinder at a constant speed according to the speed under a load.   2. The method for evaluating a pneumatic drive system according to claim 1, wherein the cylinder operating point is represented by the drive pressure and the speed of the piston.

Images