Created on:2021-06-08 10:38

Selection of hydraulic pump and motor

1.8 product overview of hydraulic pump and hydraulic motor

At present, the domestic production and sales of hydraulic pump and hydraulic motor products have basically formed a diversified pattern, mainly covering the following categories: domestic self-developed products; products manufactured by imported technology; products produced by Sino foreign joint ventures; products imitated and digested; products wholly owned by foreign companies, etc. In addition, users can download product samples directly from the Internet or ask for product samples by letter according to their needs and specific conditions of use,

1.9 selection of hydraulic pump and motor

1.9.1 selection principle and key points of hydraulic pump

In the design and use of hydraulic system, the factors to be considered when selecting hydraulic pump include structure type, working pressure, flow rate, speed, efficiency (volumetric efficiency and total efficiency), quantitative or variable, variable mode, service life, type of prime mover, noise, pressure pulsation rate, self-priming capacity, etc., as well as compatibility with hydraulic oil, size, weight and economy (purchase cost) Cost, maintainability, source and product history. Some of these factors have been written in the product samples of the hydraulic pump manufacturer or the technical charts and data in the design manual. It is necessary to study them carefully and strictly follow the provisions in the product manual. If it is not clear, it is better to ask the source unit or the manufacturer.

(1) The principle of selection is that the main engine type of hydraulic transmission is fixed equipment and walking machinery. The working conditions of these two kinds of machines are different, so the main characteristic parameters of hydraulic system and the selection of hydraulic pump are also different. The main differences between the two types of hydraulic transmission are shown in the table below.

 

The main difference of hydraulic transmission between two kinds of main engine

Projects

固 定 设 备

行 走 机 械

转速

转速固定,中速(1000~1800r/min)

转速变化,高速(2000~3000r/min或更高),最低仅500~600r/min

压力

机床一般低于7MPa,其他多数低于14MPa

一般高于14MPa,愈多场合高于21MPa

工作温度

中等(<70℃)

高(70~93℃,最高105℃)

环境温度

中等,变化不大

变化很大

环境清洁度

较清洁

较脏,有尘埃

噪声

要求低噪声,一般70dB(A),不超过80dB(A)

一般不太强调,但应低于90dB

尺寸及总量

空间宽裕,对尺寸和重量药流松

空间有限制,尺寸应小,重量应轻

 

(2) Hydraulic pump type selection gear pump, vane pump, screw pump and plunger pump have different characteristics, advantages and prices, which should be based on the host type and working conditions, power size, system pressure and system requirements for pump performance. At present, the pressure of l2mpa is higher than that of ordinary gear pump system

The piston pump is widely used in the hydraulic system. In addition, we should also consider the quantitative or variable, prime mover type, speed, volumetric efficiency, total efficiency, self-priming capacity, noise and other factors.

It needs to be carefully demonstrated whether to use a constant displacement pump or a variable displacement pump. Quantitative pump is simple and cheap, variable pump is complex and expensive, but it can save energy. See the table below for the application occasions of fixed displacement pump and variable displacement pump. Vane pump, axial piston pump and radial piston pump have quantitative pump and variable pump. The variable mechanism of variable displacement pump (especially axial variable displacement piston pump) has many forms. The control methods include manual control, internal pressure control, external pressure control, solenoid valve control, sequence valve control, proportional valve control, servo valve control, etc. The control results include proportional variable, constant voltage variable, constant current variable, constant torque variable, constant power variable, load sensing variable and so on. Not all variable pumps have the above variables and control methods. The choice of variable mode should adapt to the requirements of the system, and the static and dynamic characteristics and use methods of these variable modes should be clarified in practical use. Different types of pumps, different manufacturers, the variable machine

The product sample or instruction manual should be consulted carefully when selecting the structure.

 

Application of fixed displacement pump and variable displacement pump

定量泵

变量泵

液压功率小于10kW,而且能源成本不是重要因素

工作循环为开关式,而且泵在不工作时可完全卸载

尽管负载变化很大,但在多数工况下需要泵输出全部流量

工作制不繁重,温升不成问题

液压功率大于10kW,流量需求变化很大

要求大负载下小而静谧的运动和变负载下的快速运动

泵服务于可任意组合的多个负载

要求很大的承载能力

一个原动机驱动多个泵,而泵的装机容量大于原动机功率

 

The hydraulic pump can also be made into several pumps (which can be the same type of hydraulic pump or different types of pumps) in parallel, and use the same drive shaft of the multi pump, or can be made into a multi-stage pump with oil circuit in series. When the flow of the hydraulic system changes greatly in a working cycle, the multi pump can be selected. Multi pump usually has one oil suction port and several oil outlets. The pressure oil from each outlet can supply oil to different actuators of the system separately or together. When selecting the type and structure of the hydraulic pump, other requirements of the system for the hydraulic pump should also be considered, such as weight, price, service life, reliability, installation mode of the hydraulic pump, driving mode of the pump, connection mode between the pump and the prime mover, shaft extension form of the pump (cylindrical shaft extension, conical shaft extension with external thread, involute spline, etc.), and whether it can bear certain radial load Connection form of oil port (thread, flange), etc.

In the selection of specific products, should also consider the selection of hydraulic pump manufacturer's reputation and maintenance and accessories supply.

Home    Article     Selection of hydraulic pump and motor