液壓泵的定義：依靠密閉工作容積的改變實現(xiàn)吸、壓液體，從而將機械能轉換為液壓能的機器。

　　常用液壓泵的種類：

　　1、按流量是否可調(diào)節(jié)可分為：變量泵和定量泵。

　　輸出流量可以根據(jù)需要來調(diào)節(jié)的'稱為變量泵，流量不能調(diào)節(jié)的稱為定量泵。

　　2、按液壓系統(tǒng)中常用的泵結構分為：齒輪泵、葉片泵和柱塞泵3種。

　　齒輪泵：體積較小，結構較簡單，對油的清潔度要求不嚴，價格較便宜；但泵軸受不平衡力，磨損嚴重，泄漏較大。

　　葉片泵：分為雙作用葉片泵和單作用葉片泵。這種泵流量均勻、運轉平穩(wěn)、噪音小、作壓力和容積效率比齒輪泵高、結構比齒輪泵復雜。

    柱塞泵：容積效率高、泄漏小、可在高壓下工作、大多用於大功率液壓系統(tǒng)；但結構復雜，材料和加工精度要求高、價格貴、對油的清潔度要求高。

Hydraulic pump definition: rely on the change of sealed working volume to achieve suction, pressure liquid, so as to convert mechanical energy into hydraulic energy machine.

Types of commonly used hydraulic pumps:

1, according to whether the flow can be adjusted can be divided into: variable pump and quantitative pump.

The output flow can be adjusted according to the need 'is called variable pump, the flow can not be adjusted is called fixed pump.

2. According to the pump structure commonly used in the hydraulic system, it is divided into gear pump, vane pump and plunger pump.

Gear pump: small volume, simple structure, the cleanliness of oil requirements are not strict, the price is cheaper; But the pump shaft by unbalanced force, serious wear, large leakage.

Vane pump: divided into double - acting vane pump and single - acting vane pump. This pump flow uniform, smooth operation, low noise, pressure and volume efficiency than gear pump, structure than gear pump complex.

Plunger pump: high volume efficiency, small leakage, can work under high pressure, mostly used for high-power hydraulic system; But the structure is complex, the material and the processing precision requirements are high, the price is expensive, and the oil cleanliness requirements are high.