JP3894121B2 - pump - Google Patents

Description

【００４４】
という関係が成り立つため、これら流体の体積速度の変化率は、ΔＰ_outとＲ_out×Ｑ_outとの差をイナータンスＬ_outで割ったものと等しい。そして、1周期分の波形Ｗ３で示されている流体の体積速度を積分した値が、1周期当たりの吐出流体体積となる。
【００４５】
また、逆止弁４を通過する流体の体積速度変化の波形Ｗ３に示すように、入口流路１では、ポンプ室３内圧力が吸入側圧力Ｐ_kyよりも減少すると、その圧力差によって逆止弁４が開き、流体の体積速度が増加し始める。また、ポンプ室３内圧力が上昇し、吸入側圧力Ｐ_kyよりも増加すると、流体の体積速度が減少し始める。そして、逆止弁４の逆止効果によって逆流は防がれている。
【００４６】
ポンプ室３内圧力と吸入側圧力Ｐ_kyとの差圧をΔＰ_in、出口流路２での流体抵抗をＲ_in、イナータンスをＬ_in、流体の体積速度をＱ_inとおくと、入口流路１内の流体でも、
【００４７】
【式２】

【００４８】
という関係が成り立つため、これら流体体積速度の変化率も、ΔＰ_inとＲ_in×Ｑ_inとの差を入口流路１のイナータンスＬ_inで割ったものと等しい。
【００４９】
そして、1周期分の波形Ｗ４で示されている流体の体積速度を積分した値が、１周期当たりの吸入流体体積である。そして、この吸入流体体積は、波形Ｗ３で算出した吐出流体体積と等しい。
【００５０】
本実施形態のポンプ構造では、入口流路１のイナータンスを出口流路２のイナータンスよりも小さくしてあるので、入口流路１の流体は、大きな流体速度の変化率で流入し、吸入流体体積（＝吐出流体体積）を増加させることができる。
【００５１】
以上のように、本実施の形態のポンプは、出口流路内の流体の運動エネルギーが大きいほど、吐出流体体積が多くなりポンプの出力が大きくなるという特徴を持つ。したがって、ポンプの運転効率を向上させるうえで、圧電素子６が出力するエネルギーを効率良く出口流路の流体の運動エネルギーに変換することが重要である。また、圧電素子の保有エネルギーを、できるだけ圧電素子から出力エネルギーとして取り出すことが、圧電素子を小型化する上で重要である。
【００５２】
次に、エネルギー関係について説明する。
【００５３】
ある時刻ｔまでの圧電素子の出力エネルギーは、出口流路内の流体の運動エネルギーと、その時刻ｔまでに流体抵抗で損失されるエネルギーの和となる。ダイヤフラムが下死点から上死点まで変位した時間をＴ、その時の排除体積をＶ₀とする。また、このとき圧電素子は下死点から上死点まで変位したので、一周期分の出力エネルギーＥmaxを出力している。
【００５４】
このときのエネルギー式は、出口流路のイナータンスをＬ、出口流路内が層流である場合にハーゲン・ポアズイユの式から導かれる流路内の流体抵抗をＲ、流量をＱとすると、

【００５５】
となる。ここで、出口流路の直径ｄ、長さｌ、動作流体の密度ρ、動粘度νとすると、

であり、ともに出口流路の直径ｄ、長さｌ、の関数となっている。また、Ｅmaxは、圧電素子の材料と寸法とによって決まる保有エネルギーＥ、出口管路のコンプライアンスをＣ、圧電素子のコンプライアンスをＣpztとすると、

【００５６】
という関係で求められる。ここで、出口流路の直径ｄ、長さｌ、流体の圧縮率をβとすると、

とすれば良く、やはり、出口流路の直径ｄ、長さｌ、の関数となっている。
【００５７】
一方、圧電素子６が下死点から上死点まで変位して排除体積Ｖ₀となっている場合、この過程ではまだ吸入弁が開かないので、出口流路からの吐出流体体積がＶ₀と等しくなるまでは、ポンプ室内の圧力が負荷圧力よりも上昇しており、出口流路の流体体積速度は単調増加となる。そこで、圧電素子が一周期分の出力エネルギーＥmaxを出力した際の出口流路内流速をＱ_(T)とすると、流量Ｑを時間の一次関数

で近似でき、時刻Ｔまでの流量Ｑの積分値が、排除体積Ｖ₀と等しいため、

なる関係がある。ここで、（３）式に（４）式を代入すると、

【００５８】
となる。（５）式において、出口流路の長さｌ、直径ｄ、及び使用する圧電素子の保有エネルギーＥ、コンプライアンスＣpztが決まっていると、Ｑ_(T)以外の値が定数となるので、Ｑ_(T)を求めることができる。その算出した値Ｑ_(T)を用いて、出口流路内の流体に保存された運動エネルギー（以降の説明に出てくる、出口流路のイナータンスに保存されたエネルギーと同じ。）

【００５９】
と抵抗で消費されたエネルギー

【００６０】
とを算出することができる。以上の方法により算出した出口流路のイナータンスに保存されたエネルギーと抵抗で消費されたエネルギーとを比較した場合、請求項１に記載したように、「出口流路のイナータンスに保存されたエネルギー＞１／３×抵抗で消費されたエネルギー」の関係にあるように吐出管の長さｌ及び直径ｄを決めてやれば、圧電素子の出力エネルギーの２５％以上を出口管路のイナータンスに保存できる。より望ましくは、「出口流路のイナータンスに保存されたエネルギー＞抵抗で消費されたエネルギー」の関係にあるように吐出管の長さｌ及び直径ｄを決めてやれば、圧電素子の出力エネルギーの５０％以上を出口管路のイナータンスに保存できる。より望ましくは、「出口流路のイナータンスに保存されたエネルギー＞３×抵抗で消費されたエネルギー」の関係にあるように吐出管の長さｌ及び直径ｄを決めてやれば、圧電素子の出力エネルギーの７５％以上を出口管路のイナータンスに保存できる。
【００６１】
一方、本実施形態のポンプで使用している圧電素子や、超磁歪素子などのアクチュエータは、外部からエネルギーを加えた場合、変位が零の時が最大発生力となる。そして、発生力が零となった時が、最大変位となる。そこで、これらアクチュエータの保有エネルギーは最大発生力×最大変位として求められる。一方、圧電素子にコンプライアンス要素が取り付けられた場合は、変位量が少ない間の発生力の上昇が難くなり、圧電素子の出力エネルギーＥmaxは著しく低下する。本実施形態のポンプにおいては、ポンプをどんなに剛性を高く製作しても流体のコンプライアンスは存在し、特に出口流路の流体のコンプライアンスは必ず存在する。そのためＥmaxは最大でも、圧電素子の寸法によって決まる保有エネルギーＥ、出口流路のコンプライアンスをＣ、圧電素子のコンプライアンスをＣpztとすると、

【００６２】
という関係で求められる値となる。ここで、出口管路の直径ｄ、長さｌ、流体の圧縮率をβとすると、

【００６３】
したがって、請求項３に記載したように、少なくとも出口流路に存在する流体のコンプライアンスは、アクチュエータである圧電素子６のコンプライアンスの３倍以下とすることで、圧電素子６の保有エネルギーの約２５％は取り出せる。さらに、出口流路とポンプ室とを含んだポンプ内部の流体のコンプライアンスが、圧電素子６のコンプライアンスの３倍以下とすることで、圧電素子６の保有エネルギーの約２５％以上は取り出すことができる。
【００６４】
より望ましくは、出口流路に存在する流体のコンプライアンスは、アクチュエータである圧電素子６のコンプライアンス以下とすることで、圧電素子６の保有エネルギーの約５０％は取り出せる。さらに、出口流路とポンプ室とを含んだポンプ内部の流体のコンプライアンスが、圧電素子６のコンプライアンス以下とすることで、圧電素子６の保有エネルギーの約５０％以上は取り出すことができる。
【００６５】
より望ましくは、出口流路に存在する流体のコンプライアンスは、アクチュエータである圧電素子６のコンプライアンスの１／３以下とすることで、圧電素子６の保有エネルギーの約７５％は取り出せる。さらに、出口流路とポンプ室とを含んだポンプ内部の流体のコンプライアンスが、圧電素子６のコンプライアンスの１／３以下とすることで、圧電素子６の保有エネルギーの約７５％以上は取り出すことができ圧電素子を大幅に小型にすることができる。もしくは、圧電素子への印加電圧を大幅に低下させることができる。
【００６６】
以上の関係を実際の値を用いて算出する。
【００６７】
圧電素子はヤング率4.4E10[N/m²]、直径5[mm]、長さ10[mm]、最大変位量6[μm]の物を用いており、ダイヤフラムは圧電素子と同じ直径5[mm]の場合である。このとき、圧電素子の最大発生力は518[N]、圧電素子の保有エネルギーは1.56E-3[J]、圧電素子のコンプライアンスＣ_pztはポンプ室内の圧力が加わったときの圧電素子の体積変化量であり、4.46E-7[cm³/atm]と求められる。また、ダイヤフラムの排除体積Ｖ₀は1.18E-4[cm³]となる。
【００６８】
出口流路の直径φと長さｌとを変化させた場合の、出口流路の流体抵抗Ｒ、イナータンスＬ、コンプライアンスＣの値を下表に示す。ただし、動作流体の圧縮率4.9E-10[1/Pa]、動粘度を1E-6[m²/s]、密度1E3[kg/m³]の場合である。
【００６９】

【００７０】
また、出口流路の直径φと長さｌとを変化させた場合について、圧電素子の出力エネルギーＥmaxを（６）式によって、圧電素子が出力エネルギーＥmaxを出力した際の出口流路内流速をＱ_(T)を（５）式によって算出し、求められた出口流路内流体のイナータンスに保存されたエネルギーと圧電素子の保有エネルギーＥとの比率とを下の表に示す。
【００７１】

【００７２】
このように、出口流路の直径φと長さｌとによって、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子（ＰＺＴ）保有エネルギーとの比率が変化する様子が求められている。そこで、圧電素子の保有エネルギーを効率よく出力させ、さらに、その出力エネルギーを効率よく出口流路の流体の運動エネルギーに変換するためには、出口流路内流体のイナータンス保存されるエネルギーと圧電素子保有エネルギーとの比率が少なくとも２５％以上となるように、出口流路の直径φと長さｌとを決定する必要がある。より好ましくは、出口流路内流体のイナータンス保存されるエネルギーと圧電素子保有エネルギーとの比率が少なくとも５０％以上となるように、出口流路の直径φと長さｌとを決定すればよい。
【００７３】
上表の算出時と同様の条件のもと、出口流路の直径φと長さｌとをより広い範囲で変化させ、それぞれの場合における出口流路内流体のイナータンス保存されるエネルギーと圧電素子（ＰＺＴ）保有エネルギーとの比率を示すグラフを図３に示す。
【００７４】
図３において、横軸が出口流路の直径φ[mm]で、縦軸が出口流路の長さl[mm]である。そして、実線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が７５％以上の領域であり、一点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が５０％以上の領域であり、二点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が２５％以上の領域である。
【００７５】
次に、圧電素子の直径10[mm]、ダイヤフラムも圧電素子と同じ直径10[mm]の場合を示す。このとき、圧電素子の最大発生力は2070[N]、圧電素子の保有エネルギーは6.22E-3[J]、圧電素子のコンプライアンスＣ_pztは1.78E-6[cm³/atm]と求められる。また、ダイヤフラムの排除体積Ｖ₀は4.71E-4[cm³]となる。
【００７６】
出口流路の直径φと長さｌとを変化させた場合について、圧電素子の出力エネルギーＥmaxを（６）式によって、圧電素子が出力エネルギーＥmaxを出力した際の出口流路内流速をＱ_(T)を（５）式によって算出し、求められた出口流路内流体のイナータンスに保存されたエネルギーと圧電素子の保有エネルギーＥとの比率とを下の表に示す。

【００７７】
上表の算出時と同様の条件のもと、出口流路の直径φと長さｌとをより広い範囲で変化させ、それぞれの場合における出口流路内流体のイナータンスに保存されるエネルギーと圧電素子（ＰＺＴ）保有エネルギーとの比率を示すグラフを図４に示す。
【００７８】
図４において、横軸が出口流路の直径φ[mm]で、縦軸が出口流路の長さl[mm]である。そして、実線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が７５％以上の領域であり、一点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が５０％以上の領域であり、二点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が２５％以上の領域である。
【００７９】
次に、圧電素子の直径2[mm]、ダイヤフラムも圧電素子と同じ直径2[mm]の場合を示す。このとき、圧電素子の最大発生力は82.9[N]、圧電素子の保有エネルギーは2.49E-4[J]、圧電素子のコンプライアンスＣ_pztは7.14E-8[cm³/atm]と求められる。また、ダイヤフラムの排除体積Ｖ₀は1.88E-5[cm³]となる。
【００８０】
出口流路の直径φと長さｌとを変化させた場合について、圧電素子の出力エネルギーＥmaxを（６）式によって、圧電素子が出力エネルギーＥmaxを出力した際の出口流路内流速をＱ_(T)を（５）式によって算出し、求められた出口流路内流体のイナータンスに保存されたエネルギーと圧電素子の保有エネルギーＥとの比率とを下の表に示す。

【００８１】
上表の算出時と同様の条件のもと、出口流路の直径φと長さｌとをより広い範囲で変化させ、それぞれの場合における出口流路内流体のイナータンスに保存されるエネルギーと圧電素子（ＰＺＴ）保有エネルギーとの比率を示すグラフを図５に示す。
【００８２】
図５において、横軸が出口流路の直径φ[mm]で、縦軸が出口流路の長さl[mm]である。そして、実線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が７５％以上の領域であり、一点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が５０％以上の領域であり、二点鎖線で囲まれる領域が、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率が２５％以上の領域である。
【００８３】
一方、出口流路の長さと等価直径との関係において、等価直径に比較して長さが短すぎる場合、出口流路は管路形状というよりオリフィス形状に近くなり流体抵抗が激増して流体抵抗で消費されるエネルギーも激増し、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率は大幅に低下する。そのような状態を防止するためには、出口流路の長さは流路の等価直径の１／２以上とするのが良い。出口流路の流路断面積が変化している場合は、出口流路の長さは等価直径の平均値の１／２以上とすれば良い。
ここで、等価直径とは、等価直径をＤｅとすると
Ｄｅ＝４Ａｆ／Ｗｐ
Ａｆ:流路断面積
Ｗｐ：断面にある壁面の長さ
として定義されるものである。
【００８４】
上述の内容と図３、図４、図５とにより、圧電素子保有エネルギーを有効に出口流路内流体のイナータンスに保存させるための出口流路の寸法範囲は、流路直径φは概略７０[μm]以上で３[mm]以下、流路長さは概略４５[mm]以下の範囲である。
【００８５】
以上であるが、本発明で記載しているイナータンス、コンプライアンスは、従来からある電気系と音響系とのアナロジーで使用されているものと同様のものである。
【００８６】
【発明の効果】
以上説明したように、本発明のポンプは、弁を入口流路だけに配置すればよく、弁等の流体抵抗要素を入口流路だけに配置すればいいので、流体抵抗要素での圧力損失を減らすとともに、ポンプの信頼性を高めることができる。
【００８７】
また、ピストン或いはダイヤフラムと、それを駆動するアクチュエータとの間には変位拡大機構が配置されておらず、弁に粘性抵抗を利用していないので高周波駆動に対応し、高周波駆動することでポンプの出力を増加することができる。特に、アクチュエータとして請求項８乃至９に記載したような圧電素子や超磁歪素子を使用するときには、素子の高い周波数応答性を十分に生かし小型軽量で高出力のポンプを実現できる。
【００８８】
さらに、請求項１乃至２のような出口流路寸法とすることで、圧電素子６が出力するエネルギーの２５％以上を出口流路の流体の運動エネルギーに変換することができ、ポンプの効率が向上する。
さらに、請求項３のような出口流路寸法とすることで、圧電素子６の保有エネルギーの約２５％を出力エネルギーとして取り出すことでき、圧電素子を小型化することができる。
さらに、請求項４乃至７記載の出口流路寸法とすることで、圧電素子保有エネルギーを有効に出口流路内流体の運動エネルギーに変換することができる。
【図面の簡単な説明】
【図１】 本発明に係る実施形態のポンプ構造の縦断面を示す図である。
【図２】 実施形態のポンプ動作時の各状態量を示すグラフである。
【図３】 本実施形態のポンプにおいて圧電素子とダイヤフラムの直径がφ５[mm]である場合の、出口流路寸法と、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率との関係を示したグラフである。
【図４】 本実施形態のポンプにおいて圧電素子とダイヤフラムの直径がφ１０[mm]である場合の、出口流路寸法と、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率との関係を示したグラフである。
【図５】 本実施形態のポンプにおいて圧電素子とダイヤフラムの直径がφ２[mm]である場合の、出口流路寸法と、出口流路内流体のイナータンスに保存されるエネルギーと圧電素子保有エネルギーとの比率との関係を示したグラフである。
【符号の説明】
１ 入口流路
２ 出口流路
３ ポンプ室
４ 逆止弁
５ ダイヤフラム（可動壁）
６ 圧電素子（アクチュエータ）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive displacement pump that moves a fluid by changing a volume in a pump chamber by using a piston or a diaphragm, and more particularly, to a highly reliable pump having a high flow rate.
[0002]
[Prior art]
As a conventional pump of this type, a structure in which a check valve is attached between an inlet channel and an outlet channel and a pump chamber whose volume can be changed is generally used. (For example, see Patent Document 1)
[0003]
Also, as a pump configuration that generates a flow in one direction using the viscous resistance of the fluid, a valve is provided in the outlet channel, and the inlet channel has a larger fluid resistance than the outlet channel when the valve is opened. There is a thing of the structure made like this. (For example, see Patent Document 2)
[0004]
In addition, as a pump configuration that improves the reliability of the pump without using moving parts in the valve part, a configuration including a compression component in which the pressure drop of the inlet flow channel and the outlet flow channel is different depending on the flow direction. There are things. (For example, see Patent Document 3 and Non-Patent Document 1)
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-220357
[Patent Document 2]
JP 08-312537 A
[Patent Document 3]
Japanese National Patent Publication No. 08-506874
[Non-Patent Document 1]
Anders Olsson, An improved valve-less pumpfabricate using deep reactive ion etching, 1996 IEEE 9th Internationa1 Workshop on Micro E1ectro Mechanical Systems, p.479-484
[0006]
[Problems to be solved by the invention]
However, the configuration of Patent Document 1 requires a check valve for both the inlet channel and the outlet channel, and there is a problem that pressure loss is large when fluid passes through the two check valves. In addition, since the check valve repeatedly opens and closes, there is a risk of fatigue damage, and there is a problem that reliability increases as the number of check valves increases.
[0007]
In the configuration of Patent Document 2, it is necessary to increase the fluid resistance of the inlet-side flow path in order to reduce the backflow generated in the inlet flow path during the pump discharge stroke. Then, since the fluid is introduced into the pump chamber against the fluid resistance in the pump suction stroke, the suction stroke becomes considerably longer than the discharge stroke. Therefore, the frequency of the pump discharge / intake cycle becomes considerably low.
[0008]
A pump that moves a piston or diaphragm up and down generally has a higher flow rate and higher output as the frequency of the piston or diaphragm moving up and down is higher. However, since the configuration of Patent Document 2 can be driven only at a low frequency as described above, there is a problem that a small and high output pump cannot be realized.
[0009]
The configuration of Patent Document 3 is configured to flow a net flow rate in one direction due to a difference in pressure drop depending on the flow direction of the fluid passing through the compression component according to the increase or decrease of the pump chamber volume. As the pressure increases, the reverse flow rate increases, and there is a problem that the pump does not operate at a high load pressure. According to Non-Patent Document 1, the maximum load pressure is about 0.760 atm.
[0010]
Accordingly, the present invention aims to provide a pump capable of reducing the number of mechanical on-off valves, reducing pressure loss and improving reliability, and further efficiently converting the energy held by PZT per unit volume into pump output energy. And
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an invention according to claim 1 is directed to an actuator for displacing a movable wall such as a piston or a diaphragm, a pump chamber whose volume can be changed by the displacement of the movable wall, and an operation to the pump chamber. In a pump provided with an inlet channel for allowing fluid to flow in and an outlet channel for allowing working fluid to flow out from the pump chamber,
The inlet channel is provided with a fluid resistance element that is smaller than the fluid resistance when the working fluid flows into the pump chamber when the working fluid flows out. The dimensional relationship is such that the maximum kinetic energy stored in the fluid in the outlet channel is 1/3 or more of the energy consumed by the channel resistance until the maximum kinetic energy is stored.
[0012]
According to the pump of the first aspect, 25% or more of the output energy of the actuator can be stored as the kinetic energy of the fluid in the outlet channel.
At that time, it is desirable to determine the size of the outlet channel according to the equation of claim 2 for calculating the kinetic energy stored in the fluid in the outlet channel and the energy consumed by the channel resistance.
[0013]
According to a third aspect of the present invention, there is provided an actuator for displacing a movable wall such as a piston or a diaphragm, a pump chamber whose volume can be changed by the displacement of the movable wall, and an inlet flow path for flowing a working fluid into the pump chamber. , In a pump comprising an outlet channel for letting a working fluid flow out of the pump chamber,
The inlet channel includes a fluid resistance element that is smaller than the fluid resistance when the working fluid flows into the pump chamber, and the fluid compliance in the outlet channel Less than 3 times the compliance. According to the pump of claim 3, about 25% of the energy held by the piezoelectric element 6 can be taken out.
[0014]
Moreover, in the above claim, as described in claim 4, the length of the outlet channel is preferably ½ or more of the average of the equivalent diameters of the outlet channel.
[0015]
Furthermore, in the above claims, as described in claim 5, it is preferable that the length of the outlet channel is 45 [mm] or less.
[0016]
Furthermore, in the above claims, as described in claim 6, it is preferable that an average diameter of the outlet channel is 70 [μm] or more.
[0017]
Furthermore, in the above claims, as described in claim 7, it is preferable that the average diameter of the outlet channel is 3 [mm] or less.
[0018]
Furthermore, in the above claims, as described in claim 8, the actuator is preferably a piezoelectric element.
[0019]
According to a ninth aspect of the present invention, the actuator is preferably a giant magnetostrictive element.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below with reference to the drawings.
[0021]
First, the structure of an embodiment of a pump according to the present invention will be described with reference to FIG. FIG. 1 shows a longitudinal section of the pump of the present invention. A circular diaphragm 5 is disposed at the bottom of the cylindrical case 7. The outer periphery of the diaphragm 5 is fixedly supported by the case 7 and can be elastically deformed. On the bottom surface of the diaphragm 5, a piezoelectric element 6 that expands and contracts in the vertical direction of the drawing is arranged as an actuator for moving the diaphragm 5.
[0022]
A narrow space between the diaphragm 5 and the upper wall of the case 7 is a pump chamber 3, and an inlet channel 1 provided with a check valve 4 as a fluid resistance element toward the pump chamber 3, and always during pump operation. An outlet channel 2 which is a pipe having a narrow hole communicating with the pump chamber is opened. A part of the outer periphery of the parts constituting the inlet channel 1 serves as an inlet connecting pipe 8 for connecting an external pipe (not shown) to the pump. Further, a part of the outer periphery of the parts constituting the outlet channel 2 is an outlet connecting pipe 9 for connecting an external pipe (not shown) to the pump. Further, both the inlet channel and the outlet channel have rounded portions 15a and 15b obtained by rounding the inlet side of the working fluid. In addition, as the external pipe, a pipe made of a rubber-type material such as silicon rubber, a material that is easily deformed by the pressure in the pipe, such as another resin or a thin metal is used.
[0023]
Here, the inertance L is defined. When the cross-sectional area of the flow path is S, the length of the flow path is l, and the density of the working fluid is ρ, L = ρ × l / S. When the differential pressure of the flow path is ΔP and the flow rate flowing through the flow path is Q, the relation of ΔP = L × dQ / dt is derived by modifying the equation of motion of the fluid in the flow path using the inertance L. .
[0024]
That is, the inertance L indicates the degree of influence of the unit pressure on the time change of the flow rate. The larger the inertance L, the smaller the time change of the flow rate, and the smaller the inertance L, the greater the time change of the flow rate.
[0025]
In addition, the combined inertance related to the parallel connection of a plurality of flow paths and the series connection of a plurality of flow paths having different shapes is performed by synthesizing the inertance of individual flow paths in the same manner as the parallel connection and series connection of inductances in an electric circuit. What is necessary is just to calculate.
[0026]
In addition, the inlet channel referred to here is a channel from the inside of the pump chamber 3 to the fluid inflow side end surface of the inlet connecting pipe 8. However, when the pulsation absorbing means is connected in the middle of the pipeline, it means a flow path from the inside of the pump chamber 3 to the connection portion with the pulsation absorbing means. Furthermore, when the inlet flow paths 1 of a plurality of pumps merge, it refers to the flow path from the pump chamber 3 to the merge section. The same applies to the outlet channel.
[0027]
Based on FIG. 1, the symbol relationship of the flow path length and area of the inlet flow path 1 and the outlet flow path 2 is demonstrated. In the inlet channel 1, the length of the reduced diameter pipe section near the check valve 4 is L1, the area is S1, the length of the remaining expanded pipe section is L2, and the area is S2. In the outlet channel 2, the length of the conduit of the outlet channel 2 is L3 and the area is S3.
[0028]
The inertance relationship between the inlet channel 1 and the outlet channel 2 will be described using the above symbols and the density ρ of the working fluid.
[0029]
The inertance of the inlet channel 1 is calculated as ρ × L1 / S1 + ρ × L2 / S2. On the other hand, the inertance of the outlet channel 2 is calculated as ρ × L3 / S3. These flow paths have a dimensional relationship that satisfies ρ × L1 / S1 + ρ × L2 / S2 <ρ × L3 / S3.
[0030]
In the above configuration, the shape of the diaphragm 5 is not limited to a circular shape. Further, for example, in order to protect the pump components from an excessive load pressure applied when the pump is stopped, even if a valve element is arranged in the outlet flow path 2, it is only necessary to communicate with the pump chamber at least during pump operation. . The check valve 4 is not limited to a valve that opens and closes due to a fluid pressure difference, but may be a type that can control opening and closing with a force other than the fluid pressure difference.
[0031]
Furthermore, any actuator 6 that moves the diaphragm 5 may be used as long as it expands and contracts. However, in the pump structure of the present invention, the actuator and the diaphragm 5 are connected without a displacement magnifying mechanism. Since it can be operated at a high frequency, the piezoelectric element 6 having a high response frequency and a large output per unit volume as in the present embodiment is used, so that the flow rate is increased by high frequency driving and the fluid in the outlet channel is preserved. Energy can be increased, and a small high-power pump can be realized. For the same reason, a giant magnetostrictive element may be used.
[0032]
Further, since the mechanical on-off valve has only to be arranged on the suction side, the flow rate decrease due to the valve is reduced and the reliability is also increased.
[0033]
Next, an internal state when the pure water deaerated from the pump of the present embodiment is operated as a working fluid will be described.
[0034]
FIG. 2 shows the waveform W1 of the displacement of the diaphragm 5 when the pump is operated, the waveform W2 of the internal pressure of the pump chamber 3, the volume velocity of the fluid passing through the outlet channel 2 (the sectional area of the outlet pipe × the fluid A waveform W3 of a flow rate and an amount equal to the flow rate), and a waveform W4 of the volume velocity of the fluid passing through the check valve 4 are shown. Further, the load pressure P shown in FIG. _fu Is the fluid pressure downstream of the outlet flow rate 2 and the suction side pressure P _ky Is the fluid pressure upstream of the inlet channel 1.
[0035]
As shown by the displacement waveform W1 of the diaphragm 5, the region where the slope of the waveform is positive is a process in which the piezoelectric element 6 extends and the volume of the pump chamber 3 decreases. The region where the waveform slope is negative is a process in which the piezoelectric element 6 is contracted and the volume of the pump chamber 3 is increased.
[0036]
The flat waveform section displaced by 4.5 μm is the displacement position (top dead center) of the diaphragm 5 where the diaphragm 5 is displaced and the volume of the pump chamber 3 is minimized.
[0037]
As shown in the waveform W2 of the internal pressure of the pump chamber 3, when the process of decreasing the volume of the pump chamber 3 starts, the internal pressure of the pump chamber 3 starts to increase. Then, before the process of reducing the volume of the pump chamber 3 ends, the maximum pressure in the pump chamber 3 reaches the maximum value and begins to decrease. The point at which the internal pressure is maximum is a point at which the volume velocity of the excluded fluid by the diaphragm 5 is equal to the volume velocity of the fluid in the outlet channel 2 indicated by the waveform W3.
[0038]
This is because before this time,
“Volume velocity of the excluded fluid−volume velocity of the fluid in the outlet channel 2> 0”
Therefore, the fluid in the pump chamber 3 is compressed by that amount, and the pressure in the pump chamber 3 rises. After this time,
“Volume velocity of excluded fluid−volume velocity of fluid in outlet channel 2 <0”
This is because the compression amount of the fluid in the pump chamber 3 is reduced by that amount, and the pressure in the pump chamber 3 is lowered accordingly.
[0039]
If the volume change of the fluid in the pump chamber 3 at each time is ΔV,
"ΔV = Exhaust fluid volume by diaphragm + Intake fluid volume-Discharge fluid volume"
Therefore, the pressure in the pump chamber 3 changes according to ΔV and the compressibility of the fluid. Therefore, even in the process in which the volume of the pump chamber 3 is decreasing, the load pressure P _fu In some cases, the pressure in the pump chamber 3 may decrease. However, if the piezoelectric element 6 is abruptly displaced so as to be displaced to the top dead center while the suction fluid volume is zero, the pump chamber pressure is increased until the excluded fluid volume by the diaphragm becomes equal to the discharge fluid volume. Is the load pressure P _fu Higher than. During that time, the fluid in the outlet channel increases.
[0040]
Furthermore, in the case of FIG. 2, the pressure in the pump chamber 3 is the suction side pressure P. _ky When the pressure drops to near zero atmospheric pressure, the components dissolved in the working fluid are gasified to form bubbles and aeration, and saturation occurs near the absolute zero pressure. However, the entire flow path system including the pump is pressurized and the suction side pressure P _ky If it is high enough, aeration and cavitation may not occur.
[0041]
Further, as shown in the waveform W3 of the volume velocity of the fluid in the outlet channel 2, the pressure in the pump chamber 3 is the load pressure P in the outlet channel 2. _fu The larger period is substantially the period of increase in the volume velocity of the fluid. And the pressure in the pump chamber 3 is the load pressure P _fu When the pressure is further lowered, the volume velocity of the fluid in the outlet channel 2 also starts to decrease.
[0042]
Pump chamber 3 internal pressure and load pressure P _fu ΔP _out , R is the fluid resistance in the outlet channel 2 _out Inertance L _out , Q _out The fluid in the outlet channel 2 is
[0043]
[Formula 1]

[0044]
Therefore, the rate of change in volume velocity of these fluids is ΔP _out And R _out × Q _out Inertance L _out Equal to dividing by. Then, a value obtained by integrating the volume velocity of the fluid indicated by the waveform W3 for one cycle is the discharged fluid volume per cycle.
[0045]
Further, as shown in the waveform W3 of the change in volume velocity of the fluid passing through the check valve 4, in the inlet channel 1, the pressure in the pump chamber 3 is the suction side pressure P. _ky When the pressure decreases, the check valve 4 opens due to the pressure difference, and the volume velocity of the fluid starts to increase. Further, the pressure in the pump chamber 3 increases, and the suction side pressure P _ky The volume velocity of the fluid begins to decrease. And the backflow is prevented by the check effect of the check valve 4.
[0046]
Pump chamber 3 internal pressure and suction side pressure P _ky ΔP _in , R is the fluid resistance in the outlet channel 2 _in Inertance L _in , Q _in If the fluid in the inlet channel 1
[0047]
[Formula 2]

[0048]
Therefore, the rate of change of these fluid volume velocities is also ΔP _in And R _in × Q _in Is the difference between the inertance L of the inlet channel 1 _in Equal to dividing by.
[0049]
A value obtained by integrating the volume velocity of the fluid indicated by the waveform W4 for one cycle is the suction fluid volume per cycle. The suction fluid volume is equal to the discharge fluid volume calculated by the waveform W3.
[0050]
In the pump structure of the present embodiment, the inertance of the inlet channel 1 is made smaller than the inertance of the outlet channel 2, so that the fluid in the inlet channel 1 flows in at a large rate of change in fluid velocity, and the suction fluid volume (= Discharged fluid volume) can be increased.
[0051]
As described above, the pump according to the present embodiment has a feature that the larger the kinetic energy of the fluid in the outlet channel, the larger the volume of discharged fluid and the larger the output of the pump. Therefore, in order to improve the operation efficiency of the pump, it is important to efficiently convert the energy output from the piezoelectric element 6 into the kinetic energy of the fluid in the outlet channel. In addition, taking out the energy held by the piezoelectric element as output energy from the piezoelectric element as much as possible is important for miniaturizing the piezoelectric element.
[0052]
Next, the energy relationship will be described.
[0053]
The output energy of the piezoelectric element up to a certain time t is the sum of the kinetic energy of the fluid in the outlet channel and the energy lost by the fluid resistance up to that time t. The time when the diaphragm is displaced from the bottom dead center to the top dead center is T, and the displacement volume at that time is V ₀ And At this time, since the piezoelectric element is displaced from the bottom dead center to the top dead center, the output energy Emax for one cycle is output.
[0054]
The energy equation at this time is expressed as follows: L is the inertance of the outlet channel, R is the fluid resistance in the channel derived from the Hagen-Poiseuille equation when the outlet channel is laminar, and Q is the flow rate.

[0055]
It becomes. Here, when the diameter d of the outlet channel, the length l, the density ρ of the working fluid, and the kinematic viscosity ν,

Both are functions of the diameter d and length l of the outlet channel. Also, Emax is the stored energy E determined by the material and dimensions of the piezoelectric element, the compliance of the outlet pipe is C, and the compliance of the piezoelectric element is Cpzt.

[0056]
It is required in the relationship. Here, when the diameter d of the outlet channel, the length l, and the fluid compressibility are β,

It is a function of the diameter d and the length l of the outlet channel.
[0057]
On the other hand, the piezoelectric element 6 is displaced from the bottom dead center to the top dead center, and the excluded volume V ₀ In this case, since the suction valve is not opened yet in this process, the discharge fluid volume from the outlet channel is V ₀ Until the pressure becomes equal to the pressure in the pump chamber is higher than the load pressure, and the fluid volume velocity of the outlet channel monotonously increases. Therefore, the flow velocity in the outlet channel when the piezoelectric element outputs the output energy Emax for one cycle is expressed as Q _(T) Then, the flow rate Q is a linear function of time.

The integral value of the flow rate Q up to time T is the excluded volume V ₀ Is equal to

There is a relationship. Here, when substituting equation (4) into equation (3),

[0058]
It becomes. In the formula (5), when the length l of the outlet channel, the diameter d, the energy E of the piezoelectric element to be used, and the compliance Cpzt are determined, Q _(T) Since values other than are constants, Q _(T) Can be requested. The calculated value Q _(T) Is used to store the kinetic energy stored in the fluid in the outlet channel (same as the energy stored in the inertance of the outlet channel that appears in the following description).

[0059]
And energy consumed by resistance

[0060]
And can be calculated. When the energy stored in the inertance of the outlet channel calculated by the above method is compared with the energy consumed by the resistance, as described in claim 1, “energy stored in the inertance of the outlet channel> If the length l and the diameter d of the discharge pipe are determined so that there is a relationship of “1/3 × energy consumed by resistance”, 25% or more of the output energy of the piezoelectric element can be stored in the inertance of the outlet pipe. . More preferably, if the length l and the diameter d of the discharge pipe are determined so that “energy stored in the inertance of the outlet channel> energy consumed by the resistance” is established, the output energy of the piezoelectric element can be reduced. More than 50% can be stored in the inertance of the outlet line. More desirably, if the length l and the diameter d of the discharge pipe are determined so as to satisfy the relationship of “energy stored in the inertance of the outlet channel> 3 × energy consumed by the resistance”, the output of the piezoelectric element is obtained. More than 75% of the energy can be stored in the inertance of the exit line.
[0061]
On the other hand, actuators such as piezoelectric elements and giant magnetostrictive elements used in the pump of the present embodiment have a maximum generated force when the displacement is zero when energy is applied from the outside. The maximum displacement is when the generated force becomes zero. Therefore, the energy held by these actuators is obtained as maximum generated force × maximum displacement. On the other hand, when the compliance element is attached to the piezoelectric element, it is difficult to increase the generated force while the amount of displacement is small, and the output energy Emax of the piezoelectric element is significantly reduced. In the pump of this embodiment, no matter how rigid the pump is made, fluid compliance exists, and in particular, there is always fluid compliance in the outlet channel. Therefore, even if Emax is the maximum, the retained energy E determined by the dimensions of the piezoelectric element, the compliance of the outlet channel is C, and the compliance of the piezoelectric element is Cpzt.

[0062]
This is the value obtained from the relationship. Here, when the diameter d of the outlet pipe, the length l, and the fluid compressibility are β,

[0063]
Therefore, as described in claim 3, at least the compliance of the fluid existing in the outlet channel is not more than three times the compliance of the piezoelectric element 6 that is an actuator, so that the energy held by the piezoelectric element 6 is about 25%. Can be taken out. Furthermore, when the compliance of the fluid inside the pump including the outlet channel and the pump chamber is set to three times or less of the compliance of the piezoelectric element 6, about 25% or more of the energy held by the piezoelectric element 6 can be taken out. .
[0064]
More desirably, the compliance of the fluid existing in the outlet channel is set to be equal to or less than the compliance of the piezoelectric element 6 that is an actuator, so that about 50% of the retained energy of the piezoelectric element 6 can be taken out. Furthermore, when the compliance of the fluid inside the pump including the outlet channel and the pump chamber is set to be equal to or less than the compliance of the piezoelectric element 6, about 50% or more of the retained energy of the piezoelectric element 6 can be taken out.
[0065]
More desirably, the compliance of the fluid existing in the outlet channel is set to 1/3 or less of the compliance of the piezoelectric element 6 that is an actuator, so that about 75% of the retained energy of the piezoelectric element 6 can be taken out. Furthermore, when the compliance of the fluid inside the pump including the outlet channel and the pump chamber is 1/3 or less of the compliance of the piezoelectric element 6, about 75% or more of the energy held by the piezoelectric element 6 can be taken out. In addition, the piezoelectric element can be greatly reduced in size. Alternatively, the voltage applied to the piezoelectric element can be greatly reduced.
[0066]
The above relationship is calculated using actual values.
[0067]
The piezoelectric element has a Young's modulus of 4.4E10 [N / m ² ], A diameter of 5 [mm], a length of 10 [mm], and a maximum displacement of 6 [μm] are used, and the diaphragm has the same diameter of 5 [mm] as the piezoelectric element. At this time, the maximum generated force of the piezoelectric element is 518 [N], the retained energy of the piezoelectric element is 1.56E-3 [J], and the compliance C of the piezoelectric element _pzt Is the volume change of the piezoelectric element when the pressure in the pump chamber is applied, 4.46E-7 [cm ^Three / atm]. In addition, the excluded volume V of the diaphragm ₀ 1.18E-4 [cm ^Three It becomes.
[0068]
The values of the fluid resistance R, inertance L, and compliance C of the outlet channel when the diameter φ and the length l of the outlet channel are changed are shown in the table below. However, working fluid compressibility 4.9E-10 [1 / Pa], kinematic viscosity 1E-6 [m ² / s], density 1E3 [kg / m ^Three ].
[0069]

[0070]
Further, when the diameter φ and the length l of the outlet channel are changed, the output energy Emax of the piezoelectric element is expressed by the equation (6), and the flow velocity in the outlet channel when the piezoelectric element outputs the output energy Emax is calculated. Q _(T) Is calculated by the equation (5), and the obtained ratio of the energy stored in the inertance of the fluid in the outlet channel and the energy E held by the piezoelectric element is shown in the table below.
[0071]

[0072]
Thus, it is required that the ratio between the energy stored in the inertance of the fluid in the outlet channel and the energy held by the piezoelectric element (PZT) varies depending on the diameter φ and the length l of the outlet channel. Therefore, in order to efficiently output the retained energy of the piezoelectric element and further convert the output energy into the kinetic energy of the fluid in the outlet channel, the energy stored in the inertance fluid of the fluid in the outlet channel and the piezoelectric element It is necessary to determine the diameter φ and the length l of the outlet channel so that the ratio with the retained energy is at least 25% or more. More preferably, the diameter φ and the length l of the outlet channel may be determined so that the ratio between the energy stored in the inertance of the fluid in the outlet channel and the energy stored in the piezoelectric element is at least 50% or more.
[0073]
Under conditions similar to those in the calculation in the above table, the diameter φ and the length l of the outlet channel are changed in a wider range, and the energy stored in the outlet channel in each case and the energy stored in the piezoelectric element A graph showing the ratio with (PZT) retained energy is shown in FIG.
[0074]
In FIG. 3, the horizontal axis represents the diameter φ [mm] of the outlet channel, and the vertical axis represents the length l [mm] of the outlet channel. The region surrounded by the solid line is a region where the ratio of the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding energy is 75% or more, and the region surrounded by the alternate long and short dash line is the region inside the outlet channel. The ratio between the energy stored in the fluid inertance and the piezoelectric element holding energy is 50% or more, and the area surrounded by the two-dot chain line is the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding This is a region where the ratio to energy is 25% or more.
[0075]
Next, the case where the piezoelectric element has a diameter of 10 [mm] and the diaphragm has the same diameter as the piezoelectric element of 10 [mm] is shown. At this time, the maximum generated force of the piezoelectric element is 2070 [N], the retained energy of the piezoelectric element is 6.22E-3 [J], and the compliance C of the piezoelectric element _pzt 1.78E-6 [cm ^Three / atm]. In addition, the excluded volume V of the diaphragm ₀ Is 4.71E-4 [cm ^Three It becomes.
[0076]
In the case where the diameter φ and the length l of the outlet channel are changed, the output energy Emax of the piezoelectric element is expressed by the equation (6), and the flow velocity in the outlet channel when the piezoelectric element outputs the output energy Emax is expressed as Q. _(T) Is calculated by the equation (5), and the obtained ratio of the energy stored in the inertance of the fluid in the outlet channel and the energy E held by the piezoelectric element is shown in the table below.

[0077]
Under the same conditions as in the calculation in the above table, the diameter φ and the length l of the outlet channel are changed in a wider range, and the energy stored in the inertance of the fluid in the outlet channel and the piezoelectricity in each case FIG. 4 shows a graph showing the ratio with the element (PZT) retained energy.
[0078]
In FIG. 4, the horizontal axis is the diameter φ [mm] of the outlet channel, and the vertical axis is the length l [mm] of the outlet channel. The region surrounded by the solid line is a region where the ratio of the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding energy is 75% or more, and the region surrounded by the alternate long and short dash line is the region inside the outlet channel. The ratio between the energy stored in the fluid inertance and the piezoelectric element holding energy is 50% or more, and the area surrounded by the two-dot chain line is the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding This is a region where the ratio to energy is 25% or more.
[0079]
Next, the case where the piezoelectric element has a diameter of 2 [mm] and the diaphragm has the same diameter of 2 [mm] as the piezoelectric element will be described. At this time, the maximum generated force of the piezoelectric element is 82.9 [N], the retained energy of the piezoelectric element is 2.49E-4 [J], and the compliance C of the piezoelectric element _pzt Is 7.14E-8 [cm ^Three / atm]. In addition, the excluded volume V of the diaphragm ₀ Is 1.88E-5 [cm ^Three It becomes.
[0080]
In the case where the diameter φ and the length l of the outlet channel are changed, the output energy Emax of the piezoelectric element is expressed by the equation (6), and the flow velocity in the outlet channel when the piezoelectric element outputs the output energy Emax is expressed as Q. _(T) Is calculated by the equation (5), and the obtained ratio of the energy stored in the inertance of the fluid in the outlet channel and the energy E held by the piezoelectric element is shown in the table below.

[0081]
Under the same conditions as in the calculation in the above table, the diameter φ and the length l of the outlet channel are changed in a wider range, and the energy stored in the inertance of the fluid in the outlet channel and the piezoelectricity in each case FIG. 5 is a graph showing the ratio with the element (PZT) retained energy.
[0082]
In FIG. 5, the horizontal axis is the diameter φ [mm] of the outlet channel, and the vertical axis is the length l [mm] of the outlet channel. The region surrounded by the solid line is a region where the ratio of the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding energy is 75% or more, and the region surrounded by the alternate long and short dash line is the region inside the outlet channel. The ratio between the energy stored in the fluid inertance and the piezoelectric element holding energy is 50% or more, and the area surrounded by the two-dot chain line is the energy stored in the inertance of the fluid in the outlet channel and the piezoelectric element holding This is a region where the ratio to energy is 25% or more.
[0083]
On the other hand, in the relationship between the length of the outlet channel and the equivalent diameter, if the length is too short compared to the equivalent diameter, the outlet channel becomes closer to the orifice shape rather than the pipe shape, and the fluid resistance increases drastically. Also, the energy consumed in the flow rate increases dramatically, and the ratio between the energy stored in the inertance of the fluid in the outlet channel and the energy stored in the piezoelectric element is significantly reduced. In order to prevent such a state, the length of the outlet channel is preferably ½ or more of the equivalent diameter of the channel. When the cross-sectional area of the outlet channel has changed, the length of the outlet channel may be ½ or more of the average value of equivalent diameters.
Here, the equivalent diameter means that the equivalent diameter is De.
De = 4 Af / Wp
Af: Channel cross-sectional area
Wp: The length of the wall surface in the cross section
Is defined as
[0084]
3, 4, and 5, the dimension range of the outlet channel for effectively storing the energy stored in the piezoelectric element in the inertance of the fluid in the outlet channel is approximately 70 [ [mu] m] to 3 [mm] and the flow path length is approximately 45 [mm] or less.
[0085]
As described above, the inertance and compliance described in the present invention are the same as those used in the conventional analogy between the electrical system and the acoustic system.
[0086]
【The invention's effect】
As described above, in the pump of the present invention, the valve only needs to be disposed in the inlet flow path, and the fluid resistance element such as the valve only needs to be disposed in the inlet flow path. As well as reducing, the reliability of the pump can be increased.
[0087]
Also, no displacement magnifying mechanism is arranged between the piston or diaphragm and the actuator that drives it, and no viscous resistance is used for the valve. The output can be increased. In particular, when a piezoelectric element or a giant magnetostrictive element as described in claims 8 to 9 is used as an actuator, a small, lightweight and high-output pump can be realized by fully utilizing the high frequency response of the element.
[0088]
Furthermore, by setting the outlet channel dimensions as in claims 1 and 2, 25% or more of the energy output from the piezoelectric element 6 can be converted into the kinetic energy of the fluid in the outlet channel, and the efficiency of the pump can be improved. improves.
Furthermore, by setting the size of the outlet channel as in claim 3, about 25% of the energy held by the piezoelectric element 6 can be taken out as output energy, and the piezoelectric element can be miniaturized.
Furthermore, by setting the size of the outlet channel according to claims 4 to 7, the piezoelectric element holding energy can be effectively converted into the kinetic energy of the fluid in the outlet channel.
[Brief description of the drawings]
FIG. 1 is a view showing a longitudinal section of a pump structure according to an embodiment of the present invention.
FIG. 2 is a graph showing state quantities during pump operation of the embodiment.
FIG. 3 shows the dimensions of the outlet channel, the energy stored in the inertance of the fluid in the outlet channel, and the energy stored in the piezoelectric element when the diameter of the piezoelectric element and the diaphragm is 5 mm in the pump of the present embodiment. It is the graph which showed the relationship with the ratio.
FIG. 4 shows the dimensions of the outlet channel, the energy stored in the inertance of the fluid in the outlet channel, and the energy stored in the piezoelectric element when the diameter of the piezoelectric element and the diaphragm is 10 mm in the pump of the present embodiment. It is the graph which showed the relationship with the ratio.
FIG. 5 shows the dimensions of the outlet channel, the energy stored in the inertance of the fluid in the outlet channel, and the energy stored in the piezoelectric element when the diameter of the piezoelectric element and the diaphragm is 2 mm in the pump of the present embodiment. It is the graph which showed the relationship with the ratio.
[Explanation of symbols]
1 Inlet channel
2 outlet channel
3 Pump room
4 Check valve
5 Diaphragm (movable wall)
6 Piezoelectric elements (actuators)

Claims (6)

An actuator for displacing a movable wall such as a piston or a diaphragm, a pump chamber whose volume can be changed by the displacement of the movable wall, an inlet channel for flowing a working fluid into the pump chamber, and a working fluid flowing out from the pump chamber A pump having an outlet flow path,
The actuator is a piezoelectric element or a giant magnetostrictive element, and the inlet channel includes a fluid resistance element that is smaller than the fluid resistance when the fluid resistance flows when the working fluid flows into the pump chamber, The size of the outlet channel is such that the maximum kinetic energy stored in the outlet channel in one cycle of pump operation is 1/3 or more of the energy consumed by the channel resistance until the maximum kinetic energy is stored. Between the time when the piston or diaphragm finishes moving from bottom dead center to top dead center and the time when the pump chamber starts to increase in volume due to the start of movement from top dead center to bottom dead center. A pump characterized in that the driving waveform of the piston or diaphragm is formed so that the pressure is close to absolute 0 atmosphere. The inertance of the outlet channel is L, the displacement volume when the movable wall is displaced from the bottom dead center to the top dead center is V ₀ , the pipe line resistance of the outlet channel is R, and the actuator outputs the output energy in one cycle When the flow velocity in the outlet channel is Q _(T)

The pump according to claim 1, wherein:   The pump according to claim 1 or 2, wherein the length of the outlet channel is at least 1/2 of the average of the equivalent diameters.   The pump according to any one of claims 1 to 3, wherein the outlet channel has a length of 45 mm or less.   5. The pump according to claim 1, wherein an average diameter of the outlet channel is 70 [μm] or more.   6. The pump according to claim 1, wherein an average diameter of the outlet channel is 3 [mm] or less.

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