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1、Harbin Engineering University,Lesson 15 Text MARINE PUMPS Prof. Song Zhou,Harbin Engineering University,New Words and Expressions in Text,displacement 位移，排水量 centrifugal 离心的 rotary 旋转的 reciprocating 往复的 volute 涡形(的)，涡壳 turbine 涡轮，涡轮机 regenerative 再生的 periphery 外围，周边 mesh 啮合 helical 螺旋状的 void 空的，空旷的
2、slot 槽 elliptical 椭圆的 swash 遮蔽，隐藏 tangential 无关的 moderate 中等的，适度的 attain 达到，获得,Harbin Engineering University,The pumps employed on board ship can be divided into two main categories:,Harbin Engineering University,(i) positive displacement pumps(容积式泵) and (ii) centrifugal pumps(离心泵)。,Harbin Engineeri
3、ng University,They can be broken down into three classes: (1) reciprocating(往复式), (2) rotary(回转式) and (3) centrifugal.,Harbin Engineering University,Under reciprocating are the direct acting(直动式), power, and crank-fly-wheel types.,Harbin Engineering University,Under rotary are the gear, vane(叶片式), c
4、am-and-piston and screw types(螺杆式).,Harbin Engineering University,Under centrifugal are the volute(涡壳式), diffuser(扩散式,导轮式), mixed-flow, axial-flow and turbine or regenerative types(旋涡式).,Harbin Engineering University,Displacement pumps are those where the volume of the pump chamber is alternately(交替
5、地) increased to draw the liquid in from the suction pipe and then decreased to force the liquid out into the delivery pipe.,Harbin Engineering University,Centrifugal pumps are those wherein an impeller(叶轮) rotating at high speed throws(甩、扔) the liquid by centrifugal force from the center to the peri
6、phery of the impeller where the liquid is discharged through the delivery outlet.,Harbin Engineering University,Gear pumps consist of two or more meshing(啮合) gears spur(直齿轮), single or double helical teeth (螺旋齿) enclosed in a close-fitted housing.,Harbin Engineering University,These are used extensi
7、vely for pumping fuel oil, lubricating oil and hydraulic oil.,Harbin Engineering University,When gears are unmeshed on the inlet side, a pressure drop occurs that helps the atmospheric pressure acting on the surface of the oil in the reservoir to force it up the pipe to fill the void(空间),Harbin Engi
8、neering University,the oil is then transferred around the periphery of the pump housing.,Harbin Engineering University,As the gear teeth mesh again on the outlet side, they form a seal that prevents oil from backing up to the inlet, the oil in the void is then be forced out into the discharge line.,
9、Harbin Engineering University,All vane pumps have a rotor driven within a ring camring (叶片泵定子环) by a drive shaft coupled to a prime mover.,Harbin Engineering University,A cylindrical rotor with sliding vanes, generally in radial slots(槽), rotates within the ring.,Harbin Engineering University,In a s
10、imple vane pump(单作用叶片泵), the centre of the rotor is offset(偏移) from the centre of the ring, leaving a crescent(新月形的) shaped chamber between rotor and the ring.,Harbin Engineering University,As the rotor turns, the vanes are forced outward against the inner surface of the cam ring by centrifugal forc
11、e.,Harbin Engineering University,This outward radial movement of the vanes and turning of the rotor causes the chamber between the vanes to increase as the vanes pass further away from the inlet port.,Harbin Engineering University,This increase in volume results in a lowering of pressure until the a
12、tmospheric pressure is sufficient to force oil from the reservoir into the inlet chamber.,Harbin Engineering University,Oil from the inlet is swept away by the vanes toward the outlet port through a decreasing (volume) series of chambers until it is forced through the outlet port.,Harbin Engineering
13、 University,A vane pump of balanced design has an elliptical(椭圆的) cam ring so that two pumping chambers are formed.,Harbin Engineering University,This pump is in hydraulically balance, since the two intake ports and two outlet ports are diametrically opposed(完全相对的) to each other.,Harbin Engineering
14、University,Therefore the side loads exerted on the rotor cancel out(抵消), thereby increasing bearing life and permitting high operating pressure.,Harbin Engineering University,According to their piston arrangements, rotary-piston pumps are classified either axial or radial type.,Harbin Engineering Un
15、iversity,The pistons in an axial pump operate along the axis of the pump drive shaft. The cylinder block has a series of cylinder bores with pistons that move in and out.,Harbin Engineering University,Rotation of the drive shaft causes the pistons and the cylinder block to rotate at the same speed.,Harbin Engineering University,As the block rotates, each piston moves in and out of its cylinder, the length of stroke depend on the angle of the cylinder block with reference to the drive plate or swash plate(倾斜盘) according
