9 流量控制阀

9.1 节流阀

9.2 调速阀

9.3 流量阀的应用

实验项目（八）：流量阀的应用

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 流量阀分类

流量阀
流量阀的要点是所控制的流量的稳态性, 得到稳定流量的关键是:

大水利半径 恒定压差 温度补偿

薄壁方口 压力补偿 感温材料补偿杆

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 流量阀的流量计算

流量的控制是通过节流方式来实现的

式中：
Q = 流量 （m3/s）
A = 节流口的开口面积（m2）
Δp = 压力损失（N/m2）
Ρ = 油液密度（Ns2/m4）
α = 流量系数， 决定于节留口， 0.6 – 0.9

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 流量阀分类

流量阀
节流阀 调速阀
受压力影响 不受压力影响

受粘度影响 不受粘度影响 受粘度影响 不受粘度影响

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 流量阀分类

• 节流阀

• 调速阀

• 分流集流阀

• 刹车阀(平衡阀)

• 防管路爆破阀

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 9.1 节流阀

节流阀 单向节流阀
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 9.1 节流阀

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 9.1 节流阀

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 9.1 节流阀

最大流量
可达
3,000 l/min

法兰连接

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 9.1 节流阀

插装式
结构
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 9.1 节流阀

插装式结构

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 9.1 节流阀

双单向节流阀叠加式结构

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 9.1 节流阀

节流口设计

名称/型式 节流孔形状 节流开口面积

节流特性

由于湿周小，节流较好。但因节
细长节流孔
流路径长，流量大小与粘度有关

由于湿周小，节流较好。节流路
薄壁节流孔 径几乎为零，因而流量大小与粘
度无关

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 9.1 节流阀

三角形节流口：
在单位行程输入下，面积的变化率较小，
其可调性较好或微调性能好。

方口形节流口：
单位行程与面积的变化率是线性关系，
操控性能好。

结论：薄壁方孔最好 不同类型节流口的分辨能力

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 9.1 节流阀

MG / MK 型节流阀

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 9.1 节流阀

MG / MK 型节流阀

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 9.2 调速阀（流量阀）

流量阀用于在压力变化时保持设定流量
的恒定，流量不受负载的变化而变化。

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 9.2 调速阀

减压节流
压力补偿阀

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 9.2 调速阀

P3 P2
P2 – P3 减压节流

P3 P2

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 9.2 调速阀

防启动冲击调速阀
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 9.2 调速阀

调速阀可设计为：
• 压力补偿阀在上游
• 压力补偿阀在下游

仅仅是设计的不同风格并无使用和性能上的差别

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 9.2 调速阀

压力补偿阀
在上游

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 9.2 调速阀

压力补偿阀
在下游

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 9.2 调速阀

三通流量阀

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 9.2 调速阀

三通流量阀

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 9.2 调速阀

2FRM...2FRH...和2FRW...型
通径10 和 16
系列 3X
最高工作压力 315 bar
最大流量 160 L/min

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 9.3 流量阀的应用

优点:
液压缸的工作压力低, 所以液压缸
密封圈处的摩擦力也较低。

缺点:
液压泵(4) 的供油压力总是超出液
压缸的工作压力, 即便在液压缸只
需克服较小负载力时也会这样。 进油节流调速系统
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 9.2 调速阀

优点：
是不需要平衡阀, 而且节流产生的热
量会进入油箱中。

缺点:
此处的溢流阀(3)还需设定执行机构的
最大压力(温升较大)。即使空载运形
态下, 液压缸内全部零件都要承受最
大的工作压力 (更大的摩擦力)。 出油节流调速系统
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 9.2 调速阀

优点:
在工作行程中, 只建立起负载所需的压
力。 因此, 转化为热能的功耗较少。知
道液压缸运行到停止位, 压力才达到溢
流阀(3)的设定值。这种控制回路的热
量也进入油箱中。

旁路节流调速系统
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 实验项目（八）：流量阀的应用

项目任务：
• 通过液压摆动装置将一鼓轮从水平位置转到垂直位置，由一台液压马达完成此动作。
在移动的过程中，尽管负载发生变化，但马达的转速必须保持不变。

要求理解以下概念：
• 流量控制阀的一大特点是，其内部具有某一闭合的液压控制环路。
• 在变化的负载下，流量保持不变。
• 当入口压力发生变化时，流量保持不变。
• 当流量阀的总压差低于最小压差时，流量会降低。

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