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选择油泵需要考虑的因素
工作介质 所需要的工作压力范围 期望的速度范围 最低最高工作温度 最低最高工作介质粘度 安装要求（配管方式等） 驱动方式（连轴器等） 期望的使用寿命 最大允许噪音值 维护容易度 最高造价
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350 450
1000 - 2000 5 - 100
500 - 3000 500 - 3000 5 - 1000 10 - 1000
定量
定量/ 变量 定量 / 变量
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性能 种类 齿轮泵
额定压力 额定转速 bar rpm
最高300 500 - 6000 500 - 3000
额定排量 cc
0.2 - 200 3 - 250
变量
定量 定量 变量
内啮合齿轮泵 最高300 最高70 叶片泵
1000 - 3000 0.5 - 100
径向柱塞泵 斜轴泵 斜盘泵
最高100
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开式回路
Basic Principle of APU 轴向柱塞泵基本原理
液压泵分类
机械原理
齿轮
结构形式
齿轮泵
模式
外啮合齿轮泵 内啮合齿轮泵
模式
定量泵 定量泵 定量泵 定量泵 定量 / 变量 定量泵
摆线泵
螺杆泵 叶片 叶片泵 螺杆泵 单作用叶片泵 双作用叶片泵 活塞偏心式
柱塞
径向柱塞
定量 / 变量
定量 / 变量 定量 / 变量 定量 / 变量
3
最高额定工作压力 最高峰值压力 理论排量 实际排量 实际流量
容积效率 机械效率/总效率
额定转速 最高转速 极限吸油压力 额定功率
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实际流量
理论流量扣除内外泄漏量为实际流量
Q实际 = Q理论 - ΔQ
内泄漏：指配油盘吸油腔和压油腔之间的泄漏 外泄漏：指流向回转体外的泄漏
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液压泵要素
1. 组成工作腔 2. 产生工作腔容积变化 3. 有配油装置 4. 消除困油现象 5. 尽量实现液体静液压平衡
6. 保证寿命的轴承结构 7. 易于实现自润滑
8. 合理的吸排油设计
9. 具有变量机构
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机械效率/总效率
有于各种机械的和液压的磨损，泵的实际输 入扭矩大于理论扭矩，其比值为机械效率
M理 论 ηP M M实 际
泵的总输入功率和输出功率的比值为总效率
ηP ηP M * ηP V
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15
开式回路
4
液压泵特性
最高额定工作压力
能连续工作的最高压力
最高峰值压力 能短时工作的最高压力
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液压泵特性
理论排量
泵主轴转一转所产生的容积变化 （无泄漏的状态下，泵轴转一转排 出的液体容积：称理论几何排量）
理论流量
泵在单位时间理论上所排出的液体体积 （无泄漏的状态下，泵轴转一转排 出的液体容积：称理论流量）
Q=q*n
6
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9
额定转速
允许连续工作的最高转速
最高转速
允许短时工作的最高转速
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斜轴式柱塞单元泵（马达）原理
结构原理：如图所示。锥形柱塞的球 状端连在驱动轴上，另一端则插在缸 体孔中，缸体的轴线与驱动轴的轴线 成一角度。（参见示意图） 用作泵：驱动轴通过柱塞带动缸体转 动，柱塞则在缸体孔中来回移动，并 通过与缸体配合的配油盘完成吸油和 排油的过程。在变量泵中，缸体与驱 动轴的夹角可以在特定的范围内无级 变化，从而改变泵的排量。而在定量 泵中，这个倾角是固定不变的。 用作马达：是个逆向过程。压力油推 动柱塞在缸体孔中运动，柱塞作用在 轴法兰上的力分解后可以驱动轴产生 旋转运动。
7
液压泵特性
容积效率
泵的实际流量和理论流量之比
ηPV
Q实际 Q理论 ΔQ ΔQ 1 Q理论 Q理论 Q理论
8
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如左图。执行元件的速度（或转速 ）可以通过流量控制阀来调节。而 溢流阀可以防止系统过载，起安全 保护作用。
如右图。系统的动力元件换成了变 量泵，三位四通换向阀在中位时可 以使泵卸载。系统还加入了过滤器 、冷却器和其他辅助元件。
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闭式回路
见左图：变量液压泵和液压马达 的泄漏油通过独立的管路引回油 箱，所以系统需要补充油液。
见右图：通过一个与主泵相连的 辅助泵，可以通过两个单向阀向 这种回路的低压侧补充液压油。 多余的油通过溢流阀回油箱。
18
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轴向柱塞单元（泵＆马达）的分类
斜轴式轴向柱塞泵
斜盘式轴向柱塞泵
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2
轴偏心式
斜盘式 斜轴式
轴向柱塞
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