10/49 Hydraulic Component Design Library

10/49液压元件设计库

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.

最简单的止回阀由一个可以在有限位移范围内自由移动的球体组成。在一个极端位置，代表它是完全关闭的，代表完全阻断了水流，代表而在另一个极端位置，代表它是完全打开的。在平衡状态下，代表位置取决于两个液压端口的压力。

Figure 5: external variables of submodel BAP21

图 5:子模型BAP21的外部变量

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包含两个图标的一个球在液压流动路径。一个把球放在普通的圆形座上，代表另一个放在锥形座上。中显示了与普通座椅图标相关联的子模型

Figure 5.Note that:

图 5。请注意:

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

有两个液压流端口，代表每个端口接收一个压力作为输入；

• 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;

如果球在最右边的位置，代表流路将被堵塞，代表而如果球在最左边的位置，代表流路处于最大开度；• the rods attached to the ball are optional and have a default diameter of zero in the submodels.

附在球上的杆是可选的，代表在子模型中默认直径为零。

Hydraulic Component Design Library 11/49

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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

球会受到压力的作用，代表如果压力不平衡，代表球会移动。这意味着我们必须考虑球的惯性。其外部的细节

variables are shown in Figure 6.

变量如图 6所示。

Figure 6: external variables of submodel MECMAS21

图 6:子模型MECMAS21的外部变量

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.

图 7显示了我们正在构建的系统的两个可能版本。每个都包含止回阀和两个压力源，代表以便对其进行简单测试。为什么有两个版本？原因很简单。为了使HCD尽可能容易使用，代表许多HCD图标与两个子模型相关联。再次查看图 5，代表您将看到子模型BAP21的外部变量。BAP22的外部变量是这些变量的镜像。将从这两个系统中获得基本相同的结果，代表但是，代表为了使示例更容易理解，代表请构建如图 7(a)所示的系统。请注意，代表没有任何力源(F000)插入自由机械端口。

12/49 Hydraulic Component Design Library

12/49液压元件设计库

Figure 7: two versions of a HCD simple check valve

图 7:HCD简单止回阀的两个版本

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，代表通过选择首要子模型来设置子模型是最简单的。但是，代表如果您手动设置惯性子模型，代表您会发现有两种可能的子模型，代表它们的不同之处仅在于处理位移限制的方式。这些通常被称为终点挡板。这两种建模方法在处理终点接触的方式上有所不同:

• a perfect inelastic collision with the velocity coming instant

速度即将到来的完美非弹性碰撞

• a mechanical spring and damper.

机械弹簧和减震器。

aneously to rest or

安静地休息或

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.

这两种方法都很有用，代表但第二种方法的问题是知道如何设置弹簧和阻尼器的比率。MECMAS21使用第一种方法。

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.

在参数模式下，代表对于子模式MECMAS21，代表将质量设置为 10克(0.01千克)，代表位移下限设置为 0毫米，代表位移上限设置为 4毫米(0.004米)。子模型考虑了重量，代表因此可以设置角度。在我们的例子中，代表重力与压力相比可能是微不足道的，代表因此角度的设定值并不重要。设置库仑摩擦和静摩擦可能不合适。非零粘性摩擦会使装置更稳定，代表但实际上它通常是完全打开或完全关闭的。将粘性摩擦力设置为 0 N/(m/s)。其他参数指的是斯特里贝克摩擦力。引入这一点是因为它能使静摩擦更平稳地转变为库仑摩擦。正常情况下，代表斯特里贝克摩擦参数可以保持默认值。因为我们将库仑摩擦和静摩擦设置为零，代表它们在任何情况下都不会有效。

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，代表两个杆直径必须设置为零。最大流量系数永远不会远离默认值 0.7。临界流量控制着达到该流量系数的速度，代表通常可以保持默认值。

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压力和外力计算出来的。参照图 7(a)，代表压力的计算是基于这样一个假设，代表即右侧端口压力作用于孔口附近的区域，代表左侧端口压力作用于球的其余部分。这个假设在大多数情况下都是令人满意的

Hydraulic Component Design Library 13/49

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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.

但是提供了一个被称为喷射力的修正项。这个力会关闭球阀。一个系数，代表喷射力系数，代表用来禁用或启用这个术语。他默认为 0以禁用该术语，代表当设置为 1时将启用它。如果实验数据可用并且需要对子模型进行微调，代表则可以将其设置为其他值。

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.

将左侧压力源设置为 50巴的恒定值。将右侧压力源设置为在 1秒钟内从 0升至 100巴，代表然后在 1秒钟内升至 0巴。在打印间隔等于 0.01秒的情况下，代表在 2秒内执行模拟。图 8显示了通过止回阀的流量相对于压差的典型曲线图。请记住，代表这是一个动态子模型，代表即使压差为负，代表流量也可能不为零。即使特定压降的稳态特性是阀关闭，代表惯性也会导致球位置落后于稳态位置，代表从而导致反向流动。请注意，代表出于相似的原因，代表开始和结束曲线是不一样的。

Figure 8: flow rate through the check valve

图 8:通过止回阀的流速To get the steady-state characteristic, ramp the pressure much more slowly and increase the simulation time accordingly.

为了获得稳态特性，代表应缓慢增加压力，代表并相应增加模拟时间。

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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.

接下来，代表您将添加一个弹簧(SPR000)，代表将止回阀转换为弹簧加载装置。修改后的系统如图 9所示。将零速度源(V001)连接到弹簧的另一个端口。

Figure 9: check valves with spring

图 9:带弹簧的止回阀

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.

我们必须调整弹簧刚度和预载，代表以获得理想的特性。通过选择合适的值，代表我们可以设置破裂压力和流速压力特性。

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Figure 10: external variables of submodel SPR000

图 10:子模型 SPR000的外部变量

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.

基本位移和相应的速度在质量子模型MECMAS21中计算。如图 5和图 6所示，代表这些值通过子模型BAP21传递。图 10显示了弹簧子模型的外部变量。SPR000将接受来自BAP21的速度和来自V001的另一个速度(始终为零)。

Figure 11: parameters of SPR000

图 11:SPR 000的参数

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.

当设置弹簧参数时，代表我们将尝试给止回阀一个小的预载，代表这将决定其开启压力。图 11所示的参数将给出10 N的预载