油压泵简介--中英文翻译

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本科生毕业设计 (论文)

外文翻译

原文标题Oil pressure pump cover

译文标题油压泵简介

作者所在系别机械工程系

作者所在专业机械设计制造及其自动化

完成时间2014 年5月20

译文标题油压泵

原文标题

- 0 -

作者译名国籍

原文出处 http://www.freepatentsonline.com

原文

A hydraulic pump is a mechanical device which converts mechanical

energy into hydraulic energy.More specifically ,a pump converts the

kinetic(moving) energy of a rotating shaft into the kinetic energy of

fluid flow. The fluid flow also has potential energy that allows it to

overcome the resistance of the system to fluid flow .Remember that a pump

provides the force produce flow and transmit power . Hydraulic pressure

is caused by the load on the system and by the resistance of the

hydraulic system to fluid flow.

When operating , a hydraulic pump performs two functions. First, it

creates a partial vacuum at its inlet ,permitting the atmospheric

pressure in the fluid reservoir to push the hydraulic fluid through the

inlet strainer and line into the pump .Second, its mechanical action

delivers the fluid to its outlet and into the hydraulic systems, as shown

in Fig.5-1. As the fluid leaves the pump, it encounters the working

pressure in the system. This pressure is produced by the pressure

regulating valve, the system work load ,and flow losses in the hydraulic

tubing

A pump is classified on the basis of the physical arrangement of its

pumping mechanism and its basic principle of operating. Pumps classified

by principle of operation include positive displacement and nonpositive-

displacement types. Positive-displacement pumps are equipped with a

mechanical separation(gears,vanes,or impellers) between the inlet and

outlet, which minimizes internal leakage or slippage. Therefore,the

output of positive-displacement pumps is almost unaffected by variations

in system pressure

Nopositive-displacement pumps(such as centrifugal pumps) do not have a

positive internal separation against leakage or slippage. Because of this

slippage,the delivery of these pump is reduced as the working pressure of

a system is increased. However, nonpositive-displacement pumps deliver a

continuous flow, while positive-displacement pumps deliver an

intermittent(pulsating) flow. These pulsations are small and can be

smooth out by the accumulator or the system piping. Most hydraulic pumps

are positive-displacement pumps of the rotary type.

Positive-displacement pumps have either a fixed or variable displacement.

The volume of delivery ,or gpm, of a fixed-displacement pump can be

changed only by changing the speed of the pump, because the physical

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arrangement of the pumping mechanism cannot be changed, (This does not

mean that the flow in other portions of the system cannot be adjusted by

valves.)

The flow of a variable-displacement pump can be changed by changing the

physical arrangement of the pumping mechanism with a built-in controlling

device. This device often functions in response to system pressure or

other signals. Variable-displacement pumps are more complex than fixed-

displacement pumps and,therefore,cost more. In addition, the efficiency

of a variable-displacement pump is lower than that of a fixed-

displacement pump. This is offset somewhat by the higher overall

efficiency of a system powered by a variable-displacement pump.

Most positive-displacement pumps are classified as rotary pumps. This is

because the assembly that transfers the fluid from the pump inlet to the

pump outlet has a rotating motion. Rotary pumps are further classified

according to the mechanism that transfers the fluid-such as

gears,vanes,or screws.

A different kind of positive-displacement pump is piston pump. This pump

uses a reciprocating (back-and-forth) motion of the piston, alternately

to receive fluid on the inlet side, and to discharge fluid on the outlet

side. A radial-piston pump has a revolving assembly with several piston

assemblies built into it, and can be classified as a rotary pump. Several

types of piston pumps will be discussed later in this chapter.

The performance of different pumps is evaluated on the basis of many

factors, inculding physical characteristics, operating

characteristics,and cost. When selecting a pump, the follow pump rating

and selection factors are considered;

Capacity

Pressure

Energy consumption

Drive speed

Efficiency

Reliability

Fluid characteristics

Size and weight

Control adaptability

Service life

Installation and maintenance costs

Some of the performance characteristics of different pumps are given

in Table 5-1.Each of these selection factors is described briefly in the

following paragraph.

The primary rating of a pump is its capacity. This is also called the

delivery rate ,flow rate, or volumetric output. The capacity usually is

given in gallons per minute (gpm), cubic inches per minute(

min/

) ,or

cubic inches per revolution at specified operating conditions. Pump

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摘要：

本科生毕业设计(论文)外文翻译原文标题Oilpressurepumpcover译文标题油压泵简介作者所在系别机械工程系作者所在专业机械设计制造及其自动化完成时间2014年5月20译文标题油压泵原文标题-0-作者译名国籍原文出处http://www.freepatentsonline.com原文Ahydraulicpumpisamechanicaldevicewhichconvertsmechanicalenergyintohydraulicenergy.Morespecifically,apumpconvertsthekinetic(moving)energyofarotatingshafti...

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