10/49 Hydraulic Component Design Library

10/49液壓元件設(shè)計庫

The simplest possible check valve consists of a ball which is free to move over a limited displacement.In one extreme position it is fully closed and completely blocks the flow, and in the other extreme position it is fully open.In equilibrium, the position depends on the pressures at the two hydraulic ports.

最簡單的止回閥由一個可以在有限位移范圍內(nèi)自由移動的球體組成。在一個極端位置，代表它是完全關(guān)閉的，代表完全阻斷了水流，代表而在另一個極端位置，代表它是完全打開的。在平衡狀態(tài)下，代表位置取決于兩個液壓端口的壓力。

Figure 5: external variables of submodel BAP21

圖 5:子模型BAP21的外部變量

HCD contains two icons of a ball in a hydraulic flow path.One has the ball on a plain circular seat and the other on a conical seat.A submodel associated with the plain seat icon is shown in

HCD包含兩個圖標(biāo)的一個球在液壓流動路徑。一個把球放在普通的圓形座上，代表另一個放在錐形座上。中顯示了與普通座椅圖標(biāo)相關(guān)聯(lián)的子模型

Figure 5.Note that:

圖 5。請注意:

? there are two hydraulic flow ports and at each a pressure is received as an input;

有兩個液壓流端口，代表每個端口接收一個壓力作為輸入；

? if the ball is in the extreme right position, the flow path will be blocked whereas if it is in the extreme left position the flow path is at its maximum opening;

如果球在最右邊的位置，代表流路將被堵塞，代表而如果球在最左邊的位置，代表流路處于最大開度；? the rods attached to the ball are optional and have a default diameter of zero in the submodels.

附在球上的桿是可選的，代表在子模型中默認(rèn)直徑為零。

Hydraulic Component Design Library 11/49

液壓元件設(shè)計庫 11/49

The ball will be subject to forces due to the pressure and, if they do not balance, the ball will move.This means we must take into account the inertia of the ball.Details of its external

球會受到壓力的作用，代表如果壓力不平衡，代表球會移動。這意味著我們必須考慮球的慣性。其外部的細(xì)節(jié)

variables are shown in Figure 6.

變量如圖 6所示。

Figure 6: external variables of submodel MECMAS21

圖 6:子模型MECMAS21的外部變量

Figure 7 shows two possible versions of the system we are building.Each contains the check valve and two pressure sources to perform a simple test on it.Why two versions?The reason is simple.In order to make HCD as easy to use as possible, many HCD icons are associated with two submodels.Looking again at Figure 5, you will see the external variables of submodel BAP21.The external variables of BAP22 are a mirror image of these.You will get essentially the same results from either of these systems but, to make the example easier to follow, build the system shown in Figure 7(a).Note that there are zero force sources (F000) plugged into the free mechanical ports.

圖 7顯示了我們正在構(gòu)建的系統(tǒng)的兩個可能版本。每個都包含止回閥和兩個壓力源，代表以便對其進(jìn)行簡單測試。為什么有兩個版本？原因很簡單。為了使HCD盡可能容易使用，代表許多HCD圖標(biāo)與兩個子模型相關(guān)聯(lián)。再次查看圖 5，代表您將看到子模型BAP21的外部變量。BAP22的外部變量是這些變量的鏡像。將從這兩個系統(tǒng)中獲得基本相同的結(jié)果，代表但是，代表為了使示例更容易理解，代表請構(gòu)建如圖 7(a)所示的系統(tǒng)。請注意，代表沒有任何力源(F000)插入自由機(jī)械端口。

12/49 Hydraulic Component Design Library

12/49液壓元件設(shè)計庫

Figure 7: two versions of a HCD simple check valve

圖 7:HCD簡單止回閥的兩個版本

In Submodel mode it is simplest to set submodels by selecting Premier Submodel.However, if you set the submodel for the inertia manually, you will find there are two possible submodels which differ only in the way they treat the limitations in the displacement.These are often referred to as end stops.The two methods of modeling differ in the way they deal with the contact at an end stop:

在子模型模式下，代表通過選擇首要子模型來設(shè)置子模型是最簡單的。但是，代表如果您手動設(shè)置慣性子模型，代表您會發(fā)現(xiàn)有兩種可能的子模型，代表它們的不同之處僅在于處理位移限制的方式。這些通常被稱為終點擋板。這兩種建模方法在處理終點接觸的方式上有所不同:

? a perfect inelastic collision with the velocity coming instant

速度即將到來的完美非彈性碰撞

? a mechanical spring and damper.

機(jī)械彈簧和減震器。

aneously to rest or

安靜地休息或

Both methods are useful but the problem with the second method is knowing how to set the spring and damper rates.MECMAS21 uses the first method.

這兩種方法都很有用，代表但第二種方法的問題是知道如何設(shè)置彈簧和阻尼器的比率。MECMAS21使用第一種方法。

In Parameter mode, for the submodel MECMAS21, set the mass to 10 g (0.01 kg), the lower displacement limit to 0 mm, and the upper displacement limit to 4 mm (0.004 m).The submodel takes the weight into account and because of this, an angle can be set.In our case the weight force is probably insignificant compared with the pressure force so the value set for the angle is not critical.It is probably not appropriate to set Coulomb friction and stiction.A non-zero viscous friction would make the unit more stable but in practice it is normally fully open or fully shut.Set the viscous friction to 0 N/(m/s).The other parameters refer to Stribeck friction.This was introduced because it gives a smoother transition from stiction to Coulomb friction.Normally the Stribeck friction parameters can be left at their default value.Since we set Coulomb friction and stiction to zero they will not be effective in any case.

在參數(shù)模式下，代表對于子模式MECMAS21，代表將質(zhì)量設(shè)置為 10克(0.01千克)，代表位移下限設(shè)置為 0毫米，代表位移上限設(shè)置為 4毫米(0.004米)。子模型考慮了重量，代表因此可以設(shè)置角度。在我們的例子中，代表重力與壓力相比可能是微不足道的，代表因此角度的設(shè)定值并不重要。設(shè)置庫侖摩擦和靜摩擦可能不合適。非零粘性摩擦?xí)寡b置更穩(wěn)定，代表但實際上它通常是完全打開或完全關(guān)閉的。將粘性摩擦力設(shè)置為 0 N/(m/s)。其他參數(shù)指的是斯特里貝克摩擦力。引入這一點是因為它能使靜摩擦更平穩(wěn)地轉(zhuǎn)變?yōu)閹靵瞿Σ痢ＵＧ闆r下，代表斯特里貝克摩擦參數(shù)可以保持默認(rèn)值。因為我們將庫侖摩擦和靜摩擦設(shè)置為零，代表它們在任何情況下都不會有效。

In the submodel BAP22 both rod diameters must be set to zero.The maximum flow rate coefficient is never far from the default value of 0.7.The critical flow number controls how quickly this flow coefficient is reached and normally can be left at its default value.

在子模型BAP22中，代表兩個桿直徑必須設(shè)置為零。最大流量系數(shù)永遠(yuǎn)不會遠(yuǎn)離默認(rèn)值 0.7。臨界流量控制著達(dá)到該流量系數(shù)的速度，代表通常可以保持默認(rèn)值。

The total force on the ball is calculated from the pressures acting on the ball and from the external forces.The pressure force is calculated on the assumption that, referring to Figure 7(a), the right-hand port pressure acts on an area adjacent to the orifice and the left-hand port pressure acts on the rest of the ball.This assumption is satisfactory under most circumstances

作用在球上的重力是由作用在球上的壓力和外力計算出來的。參照圖 7(a)，代表壓力的計算是基于這樣一個假設(shè)，代表即右側(cè)端口壓力作用于孔口附近的區(qū)域，代表左側(cè)端口壓力作用于球的其余部分。這個假設(shè)在大多數(shù)情況下都是令人滿意的

Hydraulic Component Design Library 13/49

液壓元件設(shè)計庫 13/49

but there is provision for a correction term which is known as a jet force.This force tends to close the ball valve.A coefficient, the jet force coefficient, is used to disable or enable this term.It is defaulted to 0 to disable the term and when set to 1 will enable it.It can be set to other values if experimental data is available and fine-tuning of the submodel is desired.

但是提供了一個被稱為噴射力的修正項。這個力會關(guān)閉球閥。一個系數(shù)，代表噴射力系數(shù)，代表用來禁用或啟用這個術(shù)語。他默認(rèn)為 0以禁用該術(shù)語，代表當(dāng)設(shè)置為 1時將啟用它。如果實驗數(shù)據(jù)可用并且需要對子模型進(jìn)行微調(diào)，代表則可以將其設(shè)置為其他值。

Set the left-hand pressure source to a constant value of 50 bar.Set the right-hand pressure source to ramp from 0 to 100 bar in 1 second and back to 0 bar in a further 1 second.Perform a simulation over 2 seconds with a Print interval equal to 0.01 second.Figure 8 shows a typical plot of the flow rate through the check valve plotted against the differential pressure.Remember this is a dynamic submodel and the flow rate can be non-zero even when the differential pressure is negative.Even though the steady state characteristic for a particular pressure drop is for the valve to be closed, the inertia causes a ball position to lag behind the steady state position resulting in a reverse flow.Note that for similar reasons the opening and closing curves are not the same.

將左側(cè)壓力源設(shè)置為 50巴的恒定值。將右側(cè)壓力源設(shè)置為在 1秒鐘內(nèi)從 0升至 100巴，代表然后在 1秒鐘內(nèi)升至 0巴。在打印間隔等于 0.01秒的情況下，代表在 2秒內(nèi)執(zhí)行模擬。圖 8顯示了通過止回閥的流量相對于壓差的典型曲線圖。請記住，代表這是一個動態(tài)子模型，代表即使壓差為負(fù)，代表流量也可能不為零。即使特定壓降的穩(wěn)態(tài)特性是閥關(guān)閉，代表慣性也會導(dǎo)致球位置落后于穩(wěn)態(tài)位置，代表從而導(dǎo)致反向流動。請注意，代表出于相似的原因，代表開始和結(jié)束曲線是不一樣的。

Figure 8: flow rate through the check valve

圖 8:通過止回閥的流速To get the steady-state characteristic, ramp the pressure much more slowly and increase the simulation time accordingly.

為了獲得穩(wěn)態(tài)特性，代表應(yīng)緩慢增加壓力，代表并相應(yīng)增加模擬時間。

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Next you will add a spring (SPR000) to convert the check valve to a spring-loaded unit.The modified system is shown in Figure 9.Attach a zero velocity source (V001) to the other port of the spring.

接下來，代表您將添加一個彈簧(SPR000)，代表將止回閥轉(zhuǎn)換為彈簧加載裝置。修改后的系統(tǒng)如圖 9所示。將零速度源(V001)連接到彈簧的另一個端口。

Figure 9: check valves with spring

圖 9:帶彈簧的止回閥

We must adjust the spring rate and preload to give the desired characteristic.By choosing appropriate values we can set a cracking pressure and a flow rate pressure characteristic.

我們必須調(diào)整彈簧剛度和預(yù)載，代表以獲得理想的特性。通過選擇合適的值，代表我們可以設(shè)置破裂壓力和流速壓力特性。

Hydraulic Component Design Library 15/49

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Figure 10: external variables of submodel SPR000

圖 10:子模型 SPR000的外部變量

The basic displacement and the corresponding velocity are calculated within the mass submodel MECMAS21.As shown in Figure 5 and Figure 6, these values are passed through the submodel BAP21.Figure 10 shows the external variables of the spring submodel.SPR000 will accept the velocity from BAP21 and another velocity (which is always zero) from V001.

基本位移和相應(yīng)的速度在質(zhì)量子模型MECMAS21中計算。如圖 5和圖 6所示，代表這些值通過子模型BAP21傳遞。圖 10顯示了彈簧子模型的外部變量。SPR000將接受來自BAP21的速度和來自V001的另一個速度(始終為零)。

Figure 11: parameters of SPR000

圖 11:SPR 000的參數(shù)

When setting the parameters for the spring, we will try to give a small pre-load to the check valve which will determine its cracking pressure.The parameters shown in Figure 11 will give a pre-load of 10 N.

當(dāng)設(shè)置彈簧參數(shù)時，代表我們將嘗試給止回閥一個小的預(yù)載，代表這將決定其開啟壓力。圖 11所示的參數(shù)將給出10 N的預(yù)載

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