JP3539987B2

JP3539987B2 - Static pressure constant ratio control valve type static pressure device

Info

Publication number: JP3539987B2
Application number: JP11715593A
Authority: JP
Inventors: 邉紘也渡; 合 ▲あきら▼ 落
Original assignee: Toshiba Machine Co Ltd
Current assignee: Shibaura Machine Co Ltd
Priority date: 1993-05-19
Filing date: 1993-05-19
Publication date: 2004-07-07
Anticipated expiration: 2019-07-07
Also published as: JPH06330945A

Description

【０００１】
【産業上の利用分野】
本発明は、例えば負荷部の相反する側の面に互いに対向して設けられた静圧軸受用の静圧ポケットへ供給する圧油の圧力を自動調節して、その静圧軸受の静剛性を実質的に無限大にするようにした静圧定比制御弁を有する静圧装置に関する。
【０００２】
【従来の技術】
一般に、静圧軸受用の制御弁としては片側定圧比制御弁とともに、対向形静圧方式として絞り制御方式を採用した制御弁が使用されている。
【０００３】
そこで、本出願人は、特公昭５７−４１６１０号として、スプール弁方式を採用し、かつ極めて簡単な回路構成にでき、部品点数を大巾に減少させてより安価に製作できるとともに制御精度を比較的容易に確保し得るようにした静圧定比制御弁を提案した。
【０００４】
すなわち、上記本出願人が提案した静圧定比制御弁は、圧油取入れ口と弁穴とを有する弁本体と、両端と中央部の３か所にランド部を有し、中央ランド部は前記弁穴の中央部に、両端ランド部は同じ両端部にそれぞれ滑合するように配置されたスプールとからなり、前記中央ランド部の両側部と前記弁穴の中央部との間に可変絞りが、前記両端ランド部と前記弁穴の両端部との間に固定絞りがそれぞれ形成されている。
【０００５】
【発明が解決しようとする課題】
ところで、上記対向形静圧定比制御弁は一定の条件下では理論上無限剛性となるという極めて秀れた特性を発揮するが、静圧隙間を含む絞り係数が理論値からずれると急激に性能が低下する等の問題がある。一方、各絞り係数を理論値通りに製作することは極めて困難で、さらにポケット圧力による構造部材の変形も理論値からのかい離の要因となる。
【０００６】
そこで、現場調整時に上記絞り係数を簡単に最適値に調整できる装置の開発が望まれている。本発明はこのような点に鑑み、無限剛性成立の条件が現場調整に於いて可能となるようにした静圧定比制御弁方式の静圧装置を得ることを目的とする。
【０００７】
【課題を解決するための手段】
本発明は、長手方向ほぼ中央部に圧油取入れ口を有し、かつ同取入れ口に交叉するように両端が太く中央部が細く穿孔された長手方向に延びる弁穴を有する弁本体、及び両端と中央部の３ケ所にランド部が形成され、中央ランド部は前記弁穴の中央部に、両端ランド部は前記弁穴の両端部の穴にそれぞれ滑合するように嵌挿されたスプールを有し、前記中央ランド部の両端部と中央部の穴との間に可変絞りを形成するとともに両端ランド部とこれらを滑合する両端部の穴との間に固定絞りを形成し、前記圧油取入れ口から流入した圧油を、前記可変絞り、及び両端ランド部の端部に形成されている室を介して負荷部の相反する側の面に互いに対向して設けられている静圧ポケットに供給するようにした静圧定比制御弁と上記静圧ポケットとの間に、可変絞り弁を設けたことを特徴とする。
【０００８】
また、上記静圧定比制御弁の２次側に、可変絞り弁を有するブリード回路を分岐したことを特徴とする。
【０００９】
【作用】
静圧ポケットの実静圧隙間が理論静圧隙間より大きい場合には、静圧定比制御弁と静圧ポケット間に設けられている可変絞り弁を絞り方向に調整することによって無限剛性の成立条件を満足させることができる。また、実静圧隙間が理論静圧隙間より小さい場合には、ブリード回路に設けられた可変絞り弁の絞りを調整することによって同様に無限剛性の成立条件を満足させることができる。
【００１０】
【実施例】
以下、添付図面を参照して本発明の実施例について説明する。図１において、符号１は回転軸の如き負荷部であって、その負荷部１の互いに相反する側の面と対向するように静圧軸受２の静圧ポケット３ａ，３ｂが配設され、その静圧ポケット３ａ，３ｂの圧力によって上記負荷部１を支持するようになっている。
【００１１】
一方、符号４は上記静圧ポケット３ａ，３ｂの圧力を制御する静圧定比制御弁であって、その静圧定比制御弁４の弁本体５には、その長手方向ほぼ中央部に圧油取入れ口６が設けられるとともに、その圧油取入れ口６と直行するように長手方向に延びる弁穴７が設けられている。上記弁穴７はその両端部ではその径が太く、中央部では細く形成され、その弁穴７内には上記弁穴７の長手軸線に沿って左右動可能にスプール８が収納されている。
【００１２】
上記スプール８は、その中央部と両端部の３か所にランド部９，１０ａ，１０ｂを有し、この中央ランド部９が前記弁穴７の細径部７ａに滑合するようにされるとともに、両端ランド部１０ａ，１０ｂは弁穴７の両端部の太径部７ｂ₁，７ｂ₂にそれぞれ滑合するように形成され、上記弁穴７の両端開口部は蓋体１１によって閉塞されている。
【００１３】
前記弁穴７の中央部の細径部７ａの内周には、前記圧油取入れ口６に連通する周方向溝１２が形成されるとともに、上記細径部７ａの内径は、前記スプール８の中央ラント部９の外径とほぼ等しく形成され、更にこの中央ランド部９の左右両端部には尖頭状のテーパ部９ａ，９ｂが形成され、このテーパ部９ａ，９ｂと前記弁穴７の細径部７ａの内周面との間に、スプール８の移動によって絞り量が可変される可変絞り１３ａ，１３ｂが構成されている。
【００１４】
しかして、圧油取入れ口６に供給された圧油は、周方向溝１２から可変絞り１３ａ，１３ｂを通過して、中央ランド部９と両端ランド部１０ａ，１０ｂとの間にそれぞれ形成された室１４，１５に流れる。また、室１４，１５に供給された圧油は、スプール８の両端ランド部１０ａ，１０ｂに形成された長手方向に延びる溝の如き固定絞り１６ａ，１６ｂを通り、両端ランド部１０ａ，１０ｂの端部に形成されている室１７，１８に流入するようにしてある。なお、上記固定絞り１６ａ，１６ｂは、スプール８の位置にかかわらず常に一定である。
【００１５】
一方、上記室１７，１８に流入した圧油は、吐出口１９，２０から互いに対向する静圧ポケット３ａ，３ｂに供給されて負荷部１の支持を行ない、この静圧ポケット３ａ，３ｂに供給された圧油は軸受隙間を経てタンク中に放出される。
【００１６】
したがって、例えば静圧ポケット３ａの静圧隙間が小さくなりそのポケット内の圧力が上昇すると、その圧力が室１７に伝わり、その圧力によってスプール８が図において右方に作動され、可変絞り１３ａが開方向に作動され、室１７への圧油供給量が増加し、それによって静圧ポケット３ａの静圧間隙が所定値になるように敏速に制御される。
【００１７】
ところで、図２及び図３は上記静圧定比制御弁の性能特性図及び構造解析図であり、
Ａ₀：スプール８の中央ランド部９の直径（ｍｍ）
Ａ₁：スプール８の両端ランド部１０ａ，１０ｂの直径（ｍｍ）
Ｒ₁：静圧ポケットの形状係数
Ｒ₂：固定絞り１６ａ，１６ｂの絞り係数
Ｒ₃：可変絞り１３ａの絞り係数
Ｒ₄：可変絞り１３ｂの絞り係数
Ｐｓ：圧油供給圧（Ｋｇｆ／ｃｍ²）
Ｐ₁：室１７の圧力（Ｋｇｆ／ｃｍ²）
Ｐ₂：室１４の圧力（Ｋｇｆ／ｃｍ²）
Ｐ₃：室１５の圧力（Ｋｇｆ／ｃｍ²）
Ｐ₄：室１８の圧力（Ｋｇｆ／ｃｍ²）
ｔ₁，ｔ₂：静圧隙間（ｍｍ）
μ：粘性係数（Ｋｇｆ−ｓｅｃ／ｃｍ²）
ｑ₁，ｑ₂：対向する静圧ポケットの流量（ｃｍ³／ｍｉｎ）
としたとき、通過流量連続条件から各静圧ポケットの流量ｑ₁，ｑ₂は、
【００１８】
【数１】

となる。
【００１９】
また、可変絞り１３ａ，１３ｂの絞り係数Ｒ₃，Ｒ₄は、スプール８が中立位置の時の絞り係数をＲａとすると、
Ｒ₃＋Ｒ₄＝２Ｒａ …（３）
が成り立ち、さらにスプールの釣合条件から
Ｐ₁Ａ₁−（Ｐ₂−Ｐ₃）（Ａ₁−Ａ₀）−Ｐ₄Ａ₁＝０
（Ａ₁−Ａ₀）／Ａ₁＝（Ｐ₁−Ｐ₄）（Ｐ₂−Ｐ₃）＝Ｋ …（４）が成立する。
【００２０】
したがって、（１）〜（３）式からＰ₁〜Ｐ₄をＰｓについて解きこれらを（４）式に代入し、ｔ₁＝ｔ₂＝ｔとしてｔを求めると、
【００２１】
【数２】

となる。この（５）式は、定数Ａ₀，Ａ₁，Ｒ₁，Ｒ₂が決まればｔは一義的に決まり、圧力には無関係で、無限剛性対向静圧が成立することを示す。
【００２２】
しかしながら、上述のような対向形低圧比絞り方式は一定の条件下では理論上無限剛性というきわてめ秀れた特性を発揮するが、静圧ポケットの実静圧隙間ｔａが理論静圧隙間ｔ_ｔからずれると、図４に示すように、急激に性能が低下する。一方、各係数を理論値通りに製作することは困難を伴ない、さらにポケット圧力による構造部材の変形も理論値からのかい離要因となる。
【００２３】
そこで、本発明においては、図１に示すように、静圧定比制御弁４の吐出口１９，２０と静圧ポケット３ａ，３ｂとを結ぶ給油路２１，２２の途中に第１の可変絞り弁２３ａ，２３ｂがそれぞれ配設されている。また、静圧定比制御弁４の二次側すなわち上記第１の可変絞り弁２３ａ，２３ｂの上流側には、それぞれ第２の可変絞り弁２４ａ，２４ｂを有するブリード回路２５，２６が分岐導出され、その先端がタンク２７に開口されている。
【００２４】
図５は、上記第１の可変絞り弁２３ａ，２３ｂのみを設けた本発明装置の性能特性図であって、第１の可変絞り弁２３ａ，２３ｂの絞り係数Ｒ₅が０の時の無限剛性対向静圧成立条件は前記（５）式から
【００２５】
【数３】

となる。そこで、上記理論静圧隙間ｔ_ｔに対して、実静圧隙間がｔ_ａになった場合における無限剛性になるための条件は上記第１の可変絞り弁２３ａ，２３ｂの絞り係数Ｒ₅を含む静圧ポケット周りの絞り係数が理論値に一致すればよいことから次式が得られる。
【００２６】
【数４】

上式から無限剛性成立のための第１の可変絞り弁による修正絞り係数Ｒ₅を導くと、
【００２７】
【数５】

となる。したがって、第１の可変絞り弁２３ａ，２３ｂの絞り係数を上記（８）式を満足するように調整することによって、軸受部をほぼ無限剛性状態とすることができる。
【００２８】
なお、上記（８）式は実静圧隙間が理論静圧隙間より大きい場合にのみ成立し、逆の場合には成立しない。したがって、この場合第２の可変絞り弁２４ａ，２４ｂを作動させる。
【００２９】
すなわち、図６は、上記第２の可変絞り弁２４ａ、２４ｂのみを設けた装置の性能特性図であり、第２の可変絞り弁２４ａ、２４ｂの絞り係数をＲ_６とすると、理論静圧隙間ｔ_ｔに対し実静圧隙間がｔ_ａになった場合において無限剛性になるための条件から次式が得られる。
【００３０】

上式から無限剛性成立のための第２の可変絞り弁による修正絞り係数Ｒ₆を導くと、
Ｒ₆＝Ｒ₁（ｔ_ｔ ³−ｔ_ａ ³） …（１０）
となる。したがって、実静圧隙間が理論静圧隙間より小さい場合には、第２の可変絞り弁２４ａ，２４ｂの絞り係数を上記（１０）式を満足するように調整することによって、無限剛性状態とすることができる。
【００３１】
しかして、図１に示す本発明の実施例においては、実静圧隙間と理論静圧隙間とが等しい場合には、第１の可変絞り弁２３ａ，２３ｂを全開とし、第２の可変絞り弁２４ａ，２４ｂを全閉とし、又実静圧隙間が理論静圧隙間より大きい場合には、第２の可変絞り弁２４ａ，２４ｂを全閉とし、第１の可変絞り弁２３ａ，２３ｂをその絞り係数が式（８）を満足するように調整し、さらに実静圧隙間が理論静圧隙間より小さい場合には、第１の可変絞り弁２３ａ，２３ｂを全開とし、第２の可変絞り弁２４ａ，２４ｂをその絞り係数が（１０）式を満足するように調整することによって、剛性無限大の静圧隙間を得ることができきる。
【００３２】
なお、上記実施例においては軸受けに使用したものを示したが、工作機械の静圧装置や滑り面等に適用することもできる。
【００３３】
【発明の効果】
本発明は上述のように、静圧定比制御弁と静圧ポケットとの間に可変絞り弁を設け、或は静圧定比制御弁の２次側に可変絞り弁を有するブリード回路を分岐したので、上記可変絞り弁の調整によって常に剛性無限大の静圧隙間を構成することができ、その無限剛性成立の条件を現場調整で満足させることができ、静圧装置の性能を大幅に向上させることができる等の効果を奏する。
【図面の簡単な説明】
【図１】本発明の静圧装置の一実施例の概略構成を示す図。
【図２】静圧定比制御弁の性能特性図。
【図３】静圧定比制御弁の構造特性図。
【図４】理論静圧隙間からの実静圧隙間のかい離量に対する剛性値の変化を示す図。
【図５】本発明装置の一実施例における性能特性図。
【図６】本発明装置の他の実施例における性能特性図。
【符号の説明】
１負荷部
３ａ，３ｂ静圧ポケット
４静圧定比制御弁
５弁本体
６圧油取入れ口
７弁穴
８スプール
９中央ランド部
１０ａ，１０ｂ両端ランド部
１２周方向溝
１３ａ，１３ｂ可変絞り
１６ａ，１６ｂ固定絞り
１９，２０吐出口
２３ａ，２３ｂ第１の可変絞り弁
２４ａ，２４ｂ第２の可変絞り弁
２５，２６ブリード回路[0001]
[Industrial applications]
The present invention, for example, automatically adjusts the pressure of pressure oil supplied to a hydrostatic pocket for a hydrostatic bearing provided opposite to each other on opposing surfaces of a load portion, and increases the static rigidity of the hydrostatic bearing. The present invention relates to a static pressure device having a static pressure constant ratio control valve configured to be substantially infinite.
[0002]
[Prior art]
Generally, as a control valve for a static pressure bearing, a control valve employing a throttle control method as an opposed-type static pressure method is used together with a one-side constant pressure ratio control valve.
[0003]
In view of this, the present applicant has adopted, as Japanese Patent Publication No. 57-41610, the adoption of a spool valve system, an extremely simple circuit configuration, a significantly reduced number of parts, a lower cost, and a comparison of control accuracy. We have proposed a static pressure constant ratio control valve that can be easily secured.
[0004]
That is, the static pressure constant ratio control valve proposed by the present applicant has a valve body having a pressurized oil intake and a valve hole, and lands at three places at both ends and a center. At the center of the valve hole, both end lands are made up of spools arranged so as to slide on the same both ends, and a variable throttle is provided between both sides of the center land and the center of the valve hole. However, fixed restrictors are respectively formed between the land portions at both ends and both end portions of the valve hole.
[0005]
[Problems to be solved by the invention]
By the way, the above-mentioned opposed type static pressure constant ratio control valve exhibits an extremely excellent characteristic of theoretically infinite rigidity under certain conditions, but when the throttling coefficient including the static pressure gap deviates from the theoretical value, the performance rapidly increases. There are problems such as a decrease in On the other hand, it is extremely difficult to manufacture each drawing coefficient according to the theoretical value, and the deformation of the structural member due to the pocket pressure also causes the deviation from the theoretical value.
[0006]
Therefore, development of a device that can easily adjust the above-described aperture coefficient to an optimum value at the time of site adjustment is desired. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a static pressure device of a static pressure constant ratio control valve type in which conditions for establishing infinite rigidity can be adjusted in the field.
[0007]
[Means for Solving the Problems]
The present invention relates to a valve body having a pressure oil intake at a substantially central portion in the longitudinal direction, and a valve body having a longitudinally extending valve hole that is thick at both ends and narrow at a central portion so as to cross the intake, and both ends. A land portion is formed at three places, that is, a central portion, a central land portion is provided at a center portion of the valve hole, and both end land portions are provided with a spool fitted so as to be fitted to holes at both end portions of the valve hole. A variable throttle is formed between both ends of the central land portion and a hole at the center portion, and a fixed throttle is formed between the land portions at both ends and the holes at both end portions that slide between them. Static pressure pockets provided to oppose each other on the opposing surfaces of the load unit through the variable throttle and the chambers formed at the ends of the land portions at both ends of the pressurized oil flowing from the oil intake port. Between the static pressure constant ratio control valve and the above static pressure pocket. In, characterized in that a variable throttle valve.
[0008]
A bleed circuit having a variable throttle valve is branched on the secondary side of the static pressure constant ratio control valve.
[0009]
[Action]
When the actual static pressure gap of the static pressure pocket is larger than the theoretical static pressure gap, infinite rigidity is established by adjusting the variable throttle valve provided between the static pressure constant ratio control valve and the static pressure pocket in the throttle direction. The condition can be satisfied. When the actual static pressure gap is smaller than the theoretical static pressure gap, the condition for establishing infinite rigidity can be similarly satisfied by adjusting the throttle of the variable throttle valve provided in the bleed circuit.
[0010]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a load portion such as a rotary shaft, and static pressure pockets 3a and 3b of a hydrostatic bearing 2 are disposed so as to face opposite surfaces of the load portion 1 on opposite sides. The load portion 1 is supported by the pressure of the static pressure pockets 3a and 3b.
[0011]
On the other hand, reference numeral 4 denotes a static pressure constant ratio control valve for controlling the pressure of the static pressure pockets 3a and 3b. An oil intake 6 is provided, and a valve hole 7 extending in the longitudinal direction is provided so as to be orthogonal to the pressure oil intake 6. The valve hole 7 has a large diameter at both ends and a small thickness at the center. A spool 8 is accommodated in the valve hole 7 so as to be able to move left and right along the longitudinal axis of the valve hole 7.
[0012]
The spool 8 has lands 9, 10a, and 10b at three positions, that is, a center portion and both end portions, and the center land portion 9 is adapted to slide on the small-diameter portion 7a of the valve hole 7. together, both end land portion 10a, 10b is formed so as to slip fit respectively into the large-diameter portion 7b _1, 7b ₂ of both ends of the valve hole 7, both end openings of the valve hole 7 is closed by a lid 11 I have.
[0013]
A circumferential groove 12 communicating with the pressure oil intake port 6 is formed on the inner periphery of the small diameter portion 7a at the center of the valve hole 7, and the inside diameter of the small diameter portion 7a is The center land portion 9 is formed to have substantially the same outer diameter as the center land portion 9. Further, the center land portion 9 has left and right end portions formed with pointed

tapered portions

9a and 9b, and the

tapered portions

9a and 9b and the valve hole 7 are formed. Variable diaphragms 13a and 13b whose diaphragm amounts are varied by the movement of the spool 8 are formed between the small-diameter portion 7a and the inner peripheral surface.
[0014]
Thus, the pressure oil supplied to the pressure oil intake 6 passes through the variable throttles 13a and 13b from the circumferential groove 12 and is formed between the center land 9 and the land portions 10a and 10b at both ends. Flow into

chambers

14,15. The pressure oil supplied to the

chambers

14 and 15 passes through fixed throttles 16a and 16b, such as longitudinally extending grooves formed in the land portions 10a and 10b at both ends of the spool 8, and ends of the land portions 10a and 10b at both ends. It flows into the

chambers

17 and 18 formed in the section. The fixed apertures 16a and 16b are always constant regardless of the position of the spool 8.
[0015]
On the other hand, the pressure oil flowing into the

chambers

17 and 18 is supplied from the

discharge ports

19 and 20 to the opposing static pressure pockets 3a and 3b to support the load portion 1 and is supplied to the static pressure pockets 3a and 3b. The generated pressure oil is discharged into the tank through the bearing gap.
[0016]
Therefore, for example, when the static pressure gap in the static pressure pocket 3a becomes small and the pressure in the pocket rises, the pressure is transmitted to the chamber 17, and the spool 8 is actuated to the right in FIG. In the direction, the supply amount of the pressurized oil to the chamber 17 increases, whereby the static pressure gap of the static pressure pocket 3a is promptly controlled so as to have a predetermined value.
[0017]
FIGS. 2 and 3 are a performance characteristic diagram and a structural analysis diagram of the static pressure constant ratio control valve, respectively.
A ₀ : diameter (mm) of central land portion 9 of spool 8
A ₁ : Diameter (mm) of land portions 10a, 10b at both ends of spool 8
R ₁ : Shape factor of static pressure pocket R ₂ : Throttling coefficient of fixed throttles 16 a and 16 b R ₃ : Throttling coefficient of variable throttle 13 a R ₄ : Throttling coefficient of variable throttle 13 b Ps: Hydraulic oil supply pressure (Kgf / cm ² )
P ₁ : pressure of chamber 17 (Kgf / cm ² )
P ₂ : pressure of the chamber 14 (Kgf / cm ² )
P ₃ : pressure of the chamber 15 (Kgf / cm ² )
P ₄ : Pressure of chamber 18 (Kgf / cm ² )
t ₁ , t ₂ : Static pressure gap (mm)
μ: viscosity coefficient (Kgf-sec / cm ² )
q ₁ , q ₂ : flow rate of opposing static pressure pocket (cm ³ / min)
From the continuous flow rate condition, the flow rates q ₁ and q ₂ of each static pressure pocket are
[0018]
(Equation 1)

It becomes.
[0019]
Also, assuming that the aperture coefficients R ₃ and R ₄ of the variable apertures 13a and 13b are Ra when the spool 8 is in the neutral position,
R ₃ + R ₄ = 2Ra (3)
Holds further P ₁ A from balance condition of the spool _{_{_{1 - (P 2 -P 3)}}} (A 1 -A 0) -P 4 A 1 = 0
(A ₁ −A ₀ ) / A ₁ = (P ₁ −P ₄ ) (P ₂ −P ₃ ) = K (4) is established.
[0020]
Therefore, P _{1 to} P ₄ are solved for Ps from the equations (1) to (3), and these are substituted into the equation (4) to obtain t as t ₁ = t ₂ = t.
[0021]
(Equation 2)

It becomes. This equation (5) indicates that if the constants A ₀ , A ₁ , R ₁ , and R ₂ are determined, t is uniquely determined, regardless of the pressure, and an infinitely rigid opposing static pressure is established.
[0022]
However, the opposed low-pressure-ratio drawing method as described above exhibits an extremely excellent characteristic of theoretically infinite rigidity under a certain condition, but the actual static pressure gap ta of the static pressure pocket is equal to the theoretical static pressure gap t. _When it deviates from _t , as shown in FIG. 4, the performance rapidly decreases. On the other hand, it is difficult to manufacture each coefficient according to the theoretical value, and the deformation of the structural member due to the pocket pressure is also a factor of deviation from the theoretical value.
[0023]
Therefore, in the present invention, as shown in FIG. 1, a first variable throttle is provided in the

oil supply passages

21 and 22 connecting the

discharge ports

19 and 20 of the static pressure constant ratio control valve 4 and the static pressure pockets 3a and 3b. Valves 23a and 23b are provided respectively. Further, bleed

circuits

25 and 26 having second variable throttle valves 24a and 24b are respectively branched and derived on the secondary side of the static pressure constant ratio control valve 4, that is, on the upstream side of the first variable throttle valves 23a and 23b. The tip is opened to the tank 27.
[0024]
5, the first variable throttle valve 23a, a performance characteristic diagram of 23b only of the invention apparatus is provided, infinite stiffness when the first variable throttle valve 23a, is restriction factor R ₅ of 23b 0 The condition for establishing the opposing static pressure is given by the above equation (5).
[Equation 3]

It becomes. Therefore, with respect to the theoretical static圧隙between t _t, conditions for an infinite stiffness in case of inter actual static圧隙becomes t _a contains coefficients R ₅ aperture of said first variable throttle valve 23a, 23b The following equation is obtained from the fact that the drawing coefficient around the static pressure pocket only needs to match the theoretical value.
[0026]
(Equation 4)

When guiding the coefficient R ₅ aperture correction by the first variable throttle valve for infinitely rigid established from the above equation,
[0027]
(Equation 5)

It becomes. Therefore, by adjusting the throttling coefficients of the first variable throttle valves 23a and 23b so as to satisfy the above equation (8), the bearing portion can be set to a substantially infinite rigid state.
[0028]
The above equation (8) holds only when the actual static pressure gap is larger than the theoretical static pressure gap, and does not hold when the reverse is true. Therefore, in this case, the second variable throttle valves 24a and 24b are operated.
[0029]
That is, FIG. 6 is a performance characteristic diagram of the device provided the second variable throttle valve 24a, 24b only, the second variable throttle valve 24a, a restriction factor of 24b and R _6, between the theoretical static圧隙the following equation is obtained from the condition for an infinite stiffness when between actual static圧隙to t _t becomes t _a.
[0030]

Deriving a modified throttle coefficient R ₆ by the second variable throttle valve for establishing infinite rigidity from the above equation,
_{_{_{R 6 = R 1 (t t}}} 3 -t a 3) ... (10)
It becomes. Therefore, when the actual static pressure gap is smaller than the theoretical static pressure gap, the infinite rigidity state is obtained by adjusting the throttle coefficients of the second variable throttle valves 24a and 24b so as to satisfy the above equation (10). be able to.
[0031]
In the embodiment of the present invention shown in FIG. 1, when the actual static pressure gap is equal to the theoretical static pressure gap, the first variable throttle valves 23a and 23b are fully opened, and the second variable throttle valve is opened. If the actual static pressure gap is larger than the theoretical static pressure gap, the second variable throttle valves 24a and 24b are fully closed, and the first variable throttle valves 23a and 23b are throttled. The coefficient is adjusted so as to satisfy Expression (8), and when the actual static pressure gap is smaller than the theoretical static pressure gap, the first variable throttle valves 23a and 23b are fully opened, and the second variable throttle valve 24a , 24b can be adjusted such that the contraction coefficient satisfies the expression (10), whereby a static pressure gap having infinite rigidity can be obtained.
[0032]
In the above embodiment, the bearing used for the bearing is shown, but the present invention can also be applied to a static pressure device or a sliding surface of a machine tool.
[0033]
【The invention's effect】
According to the present invention, as described above, a variable throttle valve is provided between a static pressure constant ratio control valve and a static pressure pocket, or a bleed circuit having a variable throttle valve on the secondary side of the static pressure constant ratio control valve is branched. By adjusting the above-mentioned variable throttle valve, a static pressure gap with infinite rigidity can always be configured, and the conditions for establishing the infinite rigidity can be satisfied by on-site adjustment, greatly improving the performance of the static pressure device. It has effects such as being able to be performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment of a static pressure device of the present invention.
FIG. 2 is a performance characteristic diagram of a static pressure constant ratio control valve.
FIG. 3 is a structural characteristic diagram of a static pressure constant ratio control valve.
FIG. 4 is a diagram showing a change in rigidity value with respect to a separation amount of an actual static pressure gap from a theoretical static pressure gap.
FIG. 5 is a performance characteristic diagram in one embodiment of the device of the present invention.
FIG. 6 is a performance characteristic diagram in another embodiment of the device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Load part 3a, 3b Static pressure pocket 4 Static pressure constant ratio control valve 5 Valve body 6 Hydraulic oil intake 7 Valve hole 8 Spool 9 Central lands 10a, 10b Lands at both ends 12 Circumferential grooves 13a, 13b 16b Fixed

throttle

19, 20 Discharge port 23a, 23b First variable throttle valve 24a, 24b Second

variable throttle valve

25, 26 Bleed circuit

Claims

A valve body having a pressure oil intake at a substantially central portion in the longitudinal direction, and a valve body having a valve hole extending in the longitudinal direction, the both ends being thick and the central portion being thin so as to intersect with the intake, and the both ends and the central portion being provided. Land portions are formed at three places, a central land portion has a spool fitted in the center portion of the valve hole, and both end land portions have spools fitted so as to fit into holes at both end portions of the hole, respectively. A variable throttle is formed between both ends of the land portion and the hole at the center, and a fixed throttle is formed between the land portions at both ends and the holes at both ends to slide them together. Pressure oil is supplied to the static pressure pockets provided opposite to each other on opposing surfaces of the load portion through the chambers formed at the ends of the variable throttle and the land portions at both ends. between the static and pressure ratio control valve and the static pressure Pokketto, the The variable throttle valve provided on the secondary side of the electrostatic compress ratio control valve, and wherein the branched bleed circuit having a second variable throttle valve, the static and pressure ratio control valve system hydrostatic device.