JPS59199199A - Liquid pressure maintaining device - Google Patents

Abstract

PURPOSE:To reduce the time when a prescribed pressing pressure is attained and to maintain the stable pressure with inexpensive parts by interposing a flow control valve to a bypass circuit provided between a pump and a selector valve and providing a stop valve which operates the bypass line at the lower limit of a control pressure. CONSTITUTION:When a change-over valve 19 is opened toward a pressing side by a command for pressing, the entire oil quantity Q1 discharged from a hydraulic pump 16 is supplied through a check valve 18 and the valve 19 to an operating cylinder 15, by which the pressure in the cylinder 15 is sharply increased. When the pressure in the cylinder 15 attains the lower limit of a control pressure, a stop valve 22 is opened by the signal from a controller 26 to operate a bypass circuit 20 and therefore the flow Q3 set by a flow rate control valve 21 is returned through the circuit 20 to a tank. The remaining flow Q2 is therefore supplied to the cylinder 15 and the pressure in the cylinder 15 rises gently from the lower limit of the control pressure until the pressure attains the upper limit of the control pressure, when the valve 19 returns to neutral and the galve 22 is shut off so that the entire oil quantity Q1 from the pump 16 returns through the valve 19 into the tank.

Description

【発明の詳細な説明】 本発明は、タイヤプレスのドーム締付用、粉末成形プレ
スの加圧用等の静的加圧に使用される液圧加圧保持回路
に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic pressurization holding circuit used for static pressurization such as dome tightening of a tire press and pressurization of a powder molding press.

作動シリンダ（１）により被加圧部材（２）を加圧する
際に使用する圧力制御回路には、従来、第１図のサーボ
弁（３）を使用した圧力制御、第２図のリリーフ弁（４
）を使用した圧力制御、第３図の圧力補償形可変吐出ポ
ンプ（５）を使用した圧力制御、第４図の空気作動ポン
プ（６）を使用した圧力制御等がある。Conventionally, the pressure control circuit used when pressurizing the pressurized member (2) by the actuating cylinder (1) includes a pressure control circuit using a servo valve (3) shown in Fig. 1, and a pressure control circuit using a relief valve (Fig. 2). 4
), pressure control using a pressure compensated variable discharge pump (5) shown in FIG. 3, and pressure control using an air-operated pump (6) shown in FIG. 4.

しかし、第１図では、圧力検出器（７）で作動シリンダ
（１）の内圧を検出し、圧力設定器（８）で設定した圧
力と比較してサーボ増幅器（９）によりサーボ弁（３）
を駆動し、ポンプαＯからの圧油を制御しているので、
制御精度は良好であるが、サーボ弁（３）が高価であり
かつ保守が困難であった。また第２図では、電磁切換弁
０Ｄを使用し、リリーフ弁（４）で制御しているため、
回路的には最も簡単であるが、圧力調整が手動になる他
１、長時間の圧力保持の場合、リリーフ弁（４）の弁座
の摩耗等により圧力が低下する欠点があった。第８図で
は、電磁切換弁αＢを使用しているが、圧力補償弁＠を
備えた可変吐出ポンプ（５）を使用しているため、高圧
力用としては不向きであｐｌまた第２図の場合と向後に
、長時間の圧力保持では圧力低下現象があり、しかも圧
力調整が手動になる欠点があった。更に第４図では、電
へ切、換弁（９）（２）と空気作動ポンプ（６）とを組
合せたものであり、圧力調整が手動になると云う問題の
他に、空気作動ポンプ（６）自体の性能が、第５図に示
す如く設定圧力に近づくと吐出量が低下するものである
ため、超高圧力用として適しているものの、所定の加圧
力に到達する時間が長くなるという欠点があった。However, in Fig. 1, the pressure detector (7) detects the internal pressure of the operating cylinder (1), and compares it with the pressure set by the pressure setting device (8).
and controls the pressure oil from pump αO,
Although the control accuracy was good, the servo valve (3) was expensive and difficult to maintain. In addition, in Fig. 2, the electromagnetic switching valve 0D is used and the relief valve (4) is used for control.
Although this is the simplest circuit, it requires manual pressure adjustment and has the disadvantage that when pressure is maintained for a long time, the pressure decreases due to wear of the valve seat of the relief valve (4). In Fig. 8, the electromagnetic switching valve αB is used, but since it uses a variable discharge pump (5) equipped with a pressure compensation valve, it is not suitable for high pressure applications. However, there was a problem with pressure reduction when the pressure was maintained for a long time, and the pressure had to be adjusted manually. Furthermore, in Fig. 4, the electric switching valve (9) (2) is combined with an air-operated pump (6), and in addition to the problem of manual pressure adjustment, the air-operated pump (6) As shown in Figure 5, the discharge rate decreases as the pressure approaches the set pressure, so it is suitable for ultra-high pressure applications, but it has the disadvantage that it takes a long time to reach the predetermined pressure. there were.

本発明は、このような従来の問題点に鑑み、安価な部品
を使用して、所定の加圧力に達するまでの時間を短縮す
ると同時に、その圧力上昇時におけるオーバーシュート
を防止し、安定した圧力を保持できる液圧加圧保持装置
を提供するものであり、その特徴とするところは、ポン
プと作動シリンダとの間に切換弁を備え、かつ制御圧力
上下限の範囲内に圧力を制御するようにした圧力制御回
路において、ポンプと切換弁との間に、作動シリンダへ
の液量を可変するためのバイパス回路ヲ設け、このバイ
パス回路に、作動シリンダの内圧が制御圧力上限よυオ
ーバシュートしないように流量を調整する流量調節弁を
介装し、制御圧力下限でバイパス回路を作動させるため
の開閉弁を設けた点にある。In view of these conventional problems, the present invention uses inexpensive parts to shorten the time it takes to reach a predetermined pressure, and at the same time prevents overshoot when the pressure rises and maintains stable pressure. This device provides a hydraulic pressurization holding device that can hold the pressure, and its features are that it is equipped with a switching valve between the pump and the operating cylinder, and that the pressure is controlled within the upper and lower limits of the control pressure. In this pressure control circuit, a bypass circuit is provided between the pump and the switching valve to vary the amount of fluid flowing into the working cylinder, and this bypass circuit is designed to prevent the internal pressure of the working cylinder from overshooting the upper limit of the control pressure. A flow rate control valve is interposed to adjust the flow rate, and an on-off valve is provided to operate the bypass circuit at the lower limit of the control pressure.

以下、図示の実施例について本発明を詳述すると、第６
図は本発明の第１実施例を示し、０４）は被加圧部材、
α９は作動シリンダ、αＱは油圧ポンプで、モータα力
により駆動される。油圧ポンプαＧと作動シリンダｕ９
との間には、逆止斧正と電磁切換弁面とが直列に接続さ
れる。Ｃ３０）はリリーフ弁、！２１１は油圧ポンプα
Ｇと切換弁σ印との間に接続されたバイパス回路で、こ
のバイパス回路（２０１には制御流量設定用の流量調整
弁（２１）と電磁開閉弁のとが直列に接続されている。Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment.
The figure shows a first embodiment of the present invention, 04) is a pressurized member,
α9 is an operating cylinder, and αQ is a hydraulic pump, which is driven by motor α force. Hydraulic pump αG and operating cylinder u9
A check shaft and an electromagnetic switching valve surface are connected in series between. C30) is a relief valve,! 211 is hydraulic pump α
A bypass circuit is connected between G and the switching valve σ mark, and this bypass circuit (201) is connected in series with a flow rate adjustment valve (21) for setting a controlled flow rate and an electromagnetic on-off valve.

　のは作動シリンダ（１５１の内圧を検出する圧力検出
器−１のは圧力設定器、−は増幅器、郡１は０１１・Ｏ
ＦＦ　　コントローラで、検出圧力と設定圧力との比較
値により駆動され、加圧指令、解除指令に応じて切換弁
ｉ１９を切換えると共に、制御圧力上限Ｐｌで切換弁［
１９１を加圧から中立に戻すと共に、制限圧力下限Ｐ２
で開閉弁（２２＋を励磁する↓うに構成されている。従
って、制御圧力下限Ｐ２でバイパス回路ωが働き、油圧
ポンプα０からの吐出ｔ　ＱｌＯ内、その一部Ｑ３をバ
イパス回路（５））からタンクに分流させ、作動シリン
ダα９への流ｔ　Ｑ２をオーバーシュートが生じない範
囲に制限する。1 is a pressure detector that detects the internal pressure of the operating cylinder (151), 1 is a pressure setting device, - is an amplifier, and group 1 is 011・O
The FF controller is driven by the comparison value between the detected pressure and the set pressure, and switches the switching valve i19 according to the pressurization command and release command, and also switches the switching valve [i19] at the control pressure upper limit Pl.
191 from pressurized to neutral, and lower limit pressure P2
Therefore, the bypass circuit ω operates at the control pressure lower limit P2, and part of the discharge tQlO from the hydraulic pump α0 is transferred from the bypass circuit (5)) to the on-off valve (22+). The flow is diverted to the tank, and the flow tQ2 to the operating cylinder α9 is limited to a range that does not cause overshoot.

上記構成において、加圧指令により切換弁ａｍが加圧側
に開くと、油圧ポンプαＱがら吐出された全油量Ｑ】が
全て逆止弁（１８）、切換弁（１ｇｌを経て作動シリン
ダ０９へと供給され、作動シリンダ回の内圧が第７図に
示すように急速に上昇する。この時の立上り特性は、ポ
ンプ容量が小さくなるが、シリンダ容量が大きくなる程
、緩やかなものとなる。作動シリンダ（１５１の内圧が
制御圧力下限Ｐ２まで達すると、コントローラのの信号
により開閉弁（２）が開き、バイパス回路群が働くので
、流量調整弁−により設定された流ＥＥ　Ｑ３がバイパ
ス回路（支））を経てタンクへと戻されることになり、
作動シリンダ印へはその残りの流量Ｑ２が供給されて行
き、作動シリンダα９の内圧は、第７図の如く制御圧力
下限Ｐ２からはＱ２に応じて緩やかに上昇する。そして
制御圧力上限Ｐ１まで達すると、切換弁（Ｉ９）が中立
に戻ると共に、開閉弁のがバイパス回路ｔ２ｏ＋を遮断
し、油圧ポンプαＱからの吐出量Ｑ、ｌは全て切換弁１
９１を経てタンクへと戻る。制御圧力下限Ｐ２に達した
後の作動シリンダ部への流量Ｑ２は、流量制御弁ｔ２１
１による流量Ｑ３を調整することにより行なうが、第８
図に示すように急勾配で上昇して制御圧力上限Ｐ１を越
えてオーバーシュート（イ）しないように設定しておく
必要がある。なお、この勾配は、バイパス流量Ｑ３を多
くすれば緩やかになる。但し、シリンダ容量が一定とす
る。制御圧力上限Ｐ１に達して切換弁１１９）を中立に
戻した後は、作動シリンダａ９のリーク分によって徐々
に内圧が低下するが、制御圧力下限Ｐ２まで下がると、
再度、切換弁（１！Ｉ）が加圧側に開き、開閉弁固が開
くので−、作動シリンダα９の内圧は流量Ｑ２に応じて
上昇し始める。以下、同様の動作を繰返すことにより、
作動シリンダ０９の内圧、即ち加圧力Ｆは、制御圧力上
限Ｐ１と制御圧力下限Ｐ２との間に保持されるのである
。この場合、制御圧力を電気的に監視できるため、長時
間Ω圧力保持でも圧力の低下（上昇）の現象がなく、ま
た第７図に示すような設定圧力の変更は、圧力設定器□
□□の操作スイッチのみで簡単にでき、中央集中制御室
での操作が可能であると共に、コンピュータとの結合も
可能である。また所定の加圧力に到達するまでの時間を
短縮でき、しかもオーバシュートがなく、加圧保持のだ
めの圧力制御精度が著しく向上する。In the above configuration, when the switching valve am opens to the pressurizing side in response to a pressurization command, the total amount of oil Q] discharged from the hydraulic pump αQ is all transferred to the operating cylinder 09 via the check valve (18) and the switching valve (1gl). The internal pressure of the working cylinder rises rapidly as shown in Fig. 7.At this time, the rise characteristic becomes smaller as the pump capacity becomes smaller, but becomes more gradual as the cylinder capacity becomes larger. (When the internal pressure of 151 reaches the control pressure lower limit P2, the on-off valve (2) is opened by the signal from the controller, and the bypass circuit group is activated, so that the flow EE Q3 set by the flow rate adjustment valve is transferred to the bypass circuit (branch). ) and then returned to the tank.
The remaining flow rate Q2 is supplied to the operating cylinder mark, and the internal pressure of the operating cylinder α9 gradually increases from the control pressure lower limit P2 in accordance with Q2, as shown in FIG. When the control pressure reaches the upper limit P1, the switching valve (I9) returns to neutral and the on-off valve shuts off the bypass circuit t2o+, and the discharge amounts Q and l from the hydraulic pump αQ are all transferred to the switching valve 1.
91 and return to the tank. After reaching the control pressure lower limit P2, the flow rate Q2 to the working cylinder section is determined by the flow rate control valve t21.
This is done by adjusting the flow rate Q3 according to 1, but the 8th
As shown in the figure, it is necessary to set the pressure so that it does not rise steeply and exceed the control pressure upper limit P1 and overshoot (A). Note that this gradient becomes gentler if the bypass flow rate Q3 is increased. However, the cylinder capacity is assumed to be constant. After reaching the control pressure upper limit P1 and returning the switching valve 119) to neutral, the internal pressure gradually decreases due to leakage from the operating cylinder a9, but when it drops to the control pressure lower limit P2,
The switching valve (1!I) opens again to the pressurizing side and the opening/closing valve opens, so that the internal pressure of the operating cylinder α9 begins to rise in accordance with the flow rate Q2. By repeating the same operation,
The internal pressure of the actuating cylinder 09, that is, the pressurizing force F is maintained between the control pressure upper limit P1 and the control pressure lower limit P2. In this case, since the control pressure can be monitored electrically, there is no pressure drop (rise) phenomenon even when the Ω pressure is maintained for a long time, and the set pressure can be changed as shown in Figure 7 using the pressure setting device
It can be easily operated using only the □□ operation switches, can be operated from a central control room, and can also be connected to a computer. Further, the time required to reach a predetermined pressure can be shortened, and there is no overshoot, and the accuracy of pressure control for maintaining pressure can be significantly improved.

これは省エネルギ一対策として空気作動ポンプを使用し
た場合に特に顕Ｈな効果が現われる。なお、第７図中、
□□□１け第２図、及び第８図のポンプ◇ｏ（５）の場
合、器は第４図の空気作動ポンプ（６）の場合の圧力特
性を夫々示す。This effect is particularly noticeable when an air-operated pump is used as an energy-saving measure. In addition, in Figure 7,
In the case of the pump ◇o (5) in Figure 2 and Figure 8, the vessel shows the pressure characteristics of the air-operated pump (6) in Figure 4, respectively.

第９図は第２実施例を示す。本発明は、第６図に示した
実施例に限定されるものではなく、第９図に示すように
、油圧ポンプαＱと逆止弁装との間に開閉弁のを直列に
接続し、流量調整弁Ｉ２１１を有するバイパス回路ｆ２
０＋を開閉弁■に並列接続して、油圧ポンプＯＱからの
吐出量Ｑｌの一部Ｑ３をリリーフ弁ｍ＋を経てタンクに
戻すようにしても良い。FIG. 9 shows a second embodiment. The present invention is not limited to the embodiment shown in FIG. 6, but as shown in FIG. 9, an on-off valve is connected in series between the hydraulic pump αQ and the check valve device, and the flow rate is Bypass circuit f2 with regulating valve I211
0+ may be connected in parallel to the on-off valve ■, so that a portion Q3 of the discharge amount Ql from the hydraulic pump OQ is returned to the tank via the relief valve m+.

以上実施例に詳述したように本発明では、切換弁、バイ
パス回路、流量調整弁、開閉弁を組合せた構成であるた
め、サーボ弁等を使用する必要がなく、安価で保守が簡
単である。また制御圧力下限に達した時に開閉弁でバイ
パス回路を働かせ、作動シリンダへの流量を制限してい
るので、所定圧力に達するまでの時間を短縮でき、しか
もそのバイパス回路の流量調整弁で流量を調整すること
により、制御圧力上限をこえてオーバーシュートを生じ
るという現象も防止できる。従って、短時間で必要な圧
力を得ると共に、加圧力保持の制御精度が従来に比較し
て著しく向上する。As detailed in the above embodiments, the present invention has a configuration that combines a switching valve, a bypass circuit, a flow rate adjustment valve, and an on-off valve, so there is no need to use a servo valve, etc., and it is inexpensive and easy to maintain. . Furthermore, when the control pressure reaches the lower limit, the on-off valve operates the bypass circuit and limits the flow to the operating cylinder, reducing the time it takes to reach the predetermined pressure. By adjusting the pressure, it is possible to prevent the phenomenon of exceeding the control pressure upper limit and causing an overshoot. Therefore, the necessary pressure can be obtained in a short time, and the control accuracy for maintaining the applied pressure can be significantly improved compared to the conventional method.

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

第１図乃至第４図は従来例を示す油圧回路図、第５図は
空気作動ポンプの性能曲線を示す図、第６図は本発明の
第１実施例を示す油圧回路図、第７図は適正な制御流量
での圧力特性図、第８図は過大な制御流量での圧力特性
図、第９図は第２実施例を示す油圧回路図である。 α９・・・作動シリンダ、αＱ・・・油圧ポンプ、［１
ｇｌ・・・電磁切換弁、２（ｌ・−・バイパス回路、Ｚ
ｌｌ・・・流量調整弁、の・・・電磁開閉弁。1 to 4 are hydraulic circuit diagrams showing a conventional example, FIG. 5 is a diagram showing a performance curve of an air-operated pump, FIG. 6 is a hydraulic circuit diagram showing a first embodiment of the present invention, and FIG. 7 is a hydraulic circuit diagram showing a conventional example. 8 is a pressure characteristic diagram at an appropriate controlled flow rate, FIG. 8 is a pressure characteristic diagram at an excessively controlled flow rate, and FIG. 9 is a hydraulic circuit diagram showing the second embodiment. α9... Working cylinder, αQ... Hydraulic pump, [1
gl... Solenoid switching valve, 2 (l... Bypass circuit, Z
ll...Flow rate adjustment valve,...Solenoid on/off valve.

Claims (1)

【特許請求の範囲】[Claims] １、　ポンプと作動シリンダとの間に切換弁を備え、か
つ制御圧力上下限の範囲内に圧力を制御するようにした
圧力制御回路において、ポンプと切換弁との間に、作動
シリンダへの液量を可変するためのバイパス回路を設け
、このバイパス回路に、作動シリンダの内圧が制御圧力
上限よりオーバシュートしないように流量を調整する流
量調節弁を介装し、制御圧力下限でバイパス回路を作動
させるための開閉弁を設けたことを特徴とする液圧加圧
保持装置。1. In a pressure control circuit that is equipped with a switching valve between the pump and the operating cylinder and is configured to control the pressure within the upper and lower limits of the control pressure, there is a connection between the pump and the switching valve that allows fluid to flow into the operating cylinder. A bypass circuit is provided to vary the amount, and this bypass circuit is equipped with a flow control valve that adjusts the flow rate so that the internal pressure of the operating cylinder does not overshoot the upper limit of the control pressure, and the bypass circuit is activated at the lower limit of the control pressure. A hydraulic pressurization holding device characterized by being provided with an on-off valve for controlling the pressure.