伺服系统设计计算

PEN

@marcos，我喜欢你提交数据的方式。它可以很容易地进行计算而不必问太多的问题。

计算活塞面积后，还有另一个计算阀门尺寸的公式。我还没有介绍那个，因为它比较复杂。

我有一个问题。累加器在哪里？

@dragonfly，泵需要提供平均流量和多一点安全。但是，如果泵是变量泵，压力将比怠速压力低10-20％，因为在压力下降到比例带的底部之前，泵不会产生全流量。控制斜盘角度流量的弹簧刚度决定了比例带的大小。对于一些泵，比例带非常大。

峰值流量由泵和蓄能器提供。

计算累加器大小需要估计一个周期内气体体积的变化。峰值流出量与泵的平均流入量之间的差异必须随时间积分，以了解累加器中的气体量有多大变化。气体体积的变化应该是最大气体体积的10％左右，因此压力将保持在10％以内。

@marcos, I like the way you present the data.  It makes it easy to make calculations without having to ask too many questions.

There is another formula for calculating the valve size once the piston area is calculated.  I haven't present that one yet because it is more complicated.

I do have one question.  Where is the accumulator?

@dragonfly,  the pump needs to supply the average flow and a little more for safety.  However,  if the pump is a variable displacement pump the pressure will be 10-20% lower than the idle pressure because the pump doesn't produce full flow until the pressure has dropped to the bottom of the proportional band.   The stiffness of the spring that controls the flow for the swash plate angle determines how big the proportional band is.  For some pumps the proportional band is very big.

The peak flow is supplied by the pump and the accumulator.

Calculating the accumulator size requires estimating the change in the gas volume over one cycle.  The difference between the peak outflow and average inflow from the pump must be integrated over time to see how much the gas volume in the accumulator changes.   The change in gas volume should be about 10% of the total gas volume at most so the pressure will stay constant within 10%.

蜻蜓

谢谢marcos，学习了，我前面有些未解问题，希望能得到你的指点。如果你能在这里与大神们讨论结晶器伺服问题，也是我难得的学习机会，期待。

蜻蜓

PEN 发表于 2018-4-28 12:03
@marcos，我喜欢你提交数据的方式。它可以很容易地进行计算而不必问太多的问题。

计算活塞面积后，还有 ...

Accumulator这个词在前面的帖子中翻译错误，难以理解。

泵离伺服阀比较远，估计8--10m，以前的系统，定量泵流量可以提供峰值流量，小容量蓄能器在伺服阀附近，只起到稳压作用。

现在打算在泵处放置稍大点蓄能器，补充流量，在伺服阀附近放置一个小蓄能器，消除脉动，泵是定量泵，伺服阀放在油缸上，硬管连接。

蓄能器是用一个还是两个？有没有好的建议？

另外有一种说法：溢流阀放置的位置对控制也有影响，溢流阀放置的位置（放置在泵处和放置在伺服阀处）对系统控制影响大不大？

Accumulator is a word that is difficult to understand in theprevious post.

The pump is far away from the servo valve. It is estimated that8--10m, the previous system, the quantitative pump flow can provide the peakflow, the small capacity Accumulator (Accumulator) is near the servo valve,which only ACTS as a stabilizing force.

Now going to put older pump accumulator, traffic, near the servovalve placed a small accumulator, eliminate pulsation, quantitative pump, thepump is servo valves on the oil cylinder, rigid pipe connection.

Is the accumulator one or two? Any good Suggestions?

In addition, there is a saying that the position of the overflowvalve is also affected by the control. The position of the overflow valve(placed in the pump and placed at the servo valve) has little effect on thecontrol of the system.

The word "Accumulator" is erroneous in the previous postand is hard to understand.

The pump is far away from the servo valve. It is estimated that the8--10m, the previous system, the quantitative pump flow can provide peak flow,and the small capacity accumulator (Accumulator) is near the servo valve andonly plays a stabilizing effect.

Now we intend to put a little larger accumulator at the pump, addthe flow, and place a small accumulator near the servo valve to eliminate thepulsation, the pump is a quantitative pump, the servo valve is placed on thecylinder, and the hard pipe is connected.

Is the accumulator one or two? Are there any good suggestions?

Another theory is that the position of the overflow valve has aneffect on the control, and the position of the overflow valve (placed at thepump and placed at the servo valve) has little impact on the system control.

PEN

做正弦运动时这是一个很好的问题。

通常我推荐两个用于可变排量泵和阀门的蓄能器。
固定排量泵应该只需要在阀门上安装一个蓄能器。
使用两个蓄能器是一个好主意，但我认为较大的应该在阀门上

This is a good question when doing sinusoidal movements.

Usually I recommend two accumulators for variable displacement pumps and valves.
Fixed displacement pumps should only require an accumulator on the valve.
Using two accumulators is a good idea, but I think the bigger one should be on the valve.

蜻蜓

Pen teacher：
我这个例子加载频率1HZ，或者说 运动频率是1HZ，
加速度频率=运动频率= 1HZ？
还是
加速度频率=4*运动频率=4 HZ？

PEN

当正弦运动为1Hz时，加速度的频率为1Hz。

活塞，杆和负载的固有频率需要高于运动频率。 （固有频率/加速频率）的比率越高，控制越容易。 4比1是一个很好的比例。 对于大多数工业应用来说，这个比例很容易实现。

对于测试应用程序，加速频率通常要高得多。 保持四比一的比例可能太昂贵了..

一个PID控制器在4：1的比例下工作效果不好。

一个好的运动控制器可以节省资金。 当比例为2/1甚至1/1时，良好的运动控制器可以精确地控制系统，但需要高级算法。 如果他们的液压设计师可以使用下一个较小尺寸的液压缸，他可以节省泵的尺寸，蓄压器尺寸，阀门尺寸和能量来运行系统。
节省的成本可能远远超过液压控制器的成本。

When a sinusoidal motion is 1 Hz the frequency of acceleration is 1 Hz.

The natural frequency of the piston, rod and load needs to be higher than the frequency of motion.  The higher the ratio of ( natural frequency / frequency of acceleration ) is,  the easier it will be to control.  4 to 1 is a good ratio.  For most industrial applications this ratio is easy to achieve.

For testing applications the frequency of acceleration is often much higher.   Keeping a four to one ratio may be too expensive..

A PID controller will not work well below a ratio of 4 to 1.

A good motion controller can save money.   A good motion controller can control the system accuratedly when the ratio is 2/1 or even 1/1  but advanced algorithms are required.  If they hydraulic designer can use the next smaller size cylinder he saves on the pump size, accumulator size, valve size and energy to run the system.
The savings can be much more than the cost of the hydraulic motion controller.

蜻蜓

PEN 发表于 2018-4-27 11:39
1. 我们在一般液压系统内的力是方程式：F=p*A。在楼主的例子里，F是10吨
F =Pa*Aa-Pb*Ab
更好。

谢谢，我想知道：
为什么是67%，这个经验取值系数是通用的吗？另外33%消耗到哪里了？
力和位移控制时 伺服阀小开口，速度控制时伺服阀大开口， 两种情况这“67%”这个值一样吗？
Pb*Ab考虑的是回油阻力，微分方程中，负载质量中为什么没有人提到回油腔的油液移动的ma的力，回油腔油液质量是随时间变化的量。
Thank you. I want to know:
Why is it 67 percent, is the empirical coefficient universal? Where's the other 33%?
Force and displacement control servo valve small opening, speed control servo valve large openings, two cases this "67%" the same value?
Pb*Ab considers the oil return resistance, and in the differential equation, why no one refers to the force of the oil moving in the oil chamber of the oil chamber in the load quality, and the quality of the return oil chamber oil fluid is the quantity that varies with time.

Thank you. I'd like to know:
Why is 67%, is this empirical value coefficient universal? Where is the other 33%?
When the force and displacement are controlled, the servo valve has small opening, and the servo valve has large opening when the speed is controlled. Is the two value the same as "67%"?
Pb*Ab considers the resistance to oil recovery. In the differential equation, why no one in the mass of the load refers to the force of the Ma movement of the oil in the back of the oil chamber; the quality of the oil back chamber is the quantity that varies with time

PEN

我不明白67％和33％这个问题。 你是指阀门上的压降？ 我可以证明，当系统压力的三分之一超过阀门时，最有效的操作点是。 这通常是控制的最佳点。

通常情况下，阀门和活塞之间的油量会被忽略，因为负载的质量要大得多。 当活塞，杆和负载的质量很小时，不应忽视阀门和活塞之间的油量。

I don't understand the question about 67% and 33%.  Are you referring to the pressure drop across the valve?  I can prove the most  efficient operating point is when 1/3 of the system pressure is across the valve.   This usually is the optimal point for control..

Normally the mass of oil between the valve and the piston is ignored because the mass of the load is so much greater.   The mass of oil beween the valve and the piston shouldn't be ignored when the mass of the piston, rod and load are small.

蜻蜓

谢谢，是，  我是问33%是不是消耗在伺服阀上，您已经给出答案。我大体明白了我现在想知道的问题，这种负载可能很难控制，在实施的过程中有问题再请教。pen专家能在这里答疑解惑，机会难得，大家如果有问题请继续。

Thank you. Yes, Iasked 33% if it was consumed on the servo valve and you have the answer. I havegenerally understood what I want to know now, which may be difficult tocontrol, and ask questions in the process of implementation. The pen expert cananswer questions here, the opportunity is rare, if you have any questions,please continue.

数字液压

@蜻蜓 看你基本了解清楚了使用伺服阀系统实现的方法，也给你另外一种实现方法的参考。

液压振动

这个视频与你提的要求基本相同，是我们十多年前在冶金领域使用数字缸实现的应用，可供你参考。如果你有兴趣，我会提供更详细的配置信息。

液压振动-板坯2

液压振动-板坯3

液压振动-板坯1

这是冶金领域的大板坯连铸结晶器数字液压振动系统，用户最直观检测双缸同步的测试方法是振动台上立一个1元硬币，硬币不倒说明双缸同步不会导致结晶器振动台偏摆。