由于各(gè)螺杆的相(xiàng)互齧合以(yi)及螺杆與(yǔ)襯筒内壁(bi)的緊密配(pèi)合，在泵的(de)吸入口和(he)排出口之(zhī)間，就會被(bei)分隔成一(yī)個或多個(gè)密封空間(jiān)。随着螺杆(gan)的轉動和(hé)齧合，這些(xie)密封空間(jiān)在泵的吸(xī)入端不斷(duàn)形成，将吸(xi)入室中的(de)液體封入(ru)其中，并自(zi)吸入室沿(yan)螺杆軸向(xiàng)連續地推(tui)移至排出(chu)端，将封閉(bi)在 各空間(jian)中的液體(ti)不斷排出(chū)，猶如一螺(luó)母在螺紋(wen)回轉時被(bei)不斷向前(qian)推進的情(qíng)形那樣，其(qí)中螺紋圈(quan)數看做液(yè)體，當螺釘(dìng)旋轉時螺(luo)紋在轉動(dong)時就相當(dang)于液體在(zài)螺杆泵裡(li)面的情形(xíng)，這就是螺(luó)杆泵的基(ji)本工作原(yuan)理。螺杆與(yǔ)殼體之間(jian)的密封面(mian)是一個空(kōng)間曲面。在(zai)這個曲面(miàn)上存在着(zhe)諸如ab或de之(zhī)類的非密(mì)封區，并且(qiě)與螺杆的(de)凹槽部分(fèn)形成許多(duo)三角形的(de)缺口abc、def。這些(xie)三角形 的(de)缺口構成(chéng)液體的通(tōng)道，使主動(dòng)螺杆凹槽(cáo)A與從動螺(luó)杆上的凹(āo)槽B、C相連通(tong)。而凹槽B、C又(you)沿着自己(ji)的螺線繞(rào)向背面， 并(bing)分别和背(bèi)面的凹槽(cao)D、E相連通。由(yóu)于在槽D、E與(yǔ)槽F(它屬于(yu)另一頭螺(luó)線)相銜接(jie)的密封面(mian)上，也存在(zài)着類似于(yú)正面的三(san)角形缺口(kǒu)a’b’c’，所以D、F、E也将(jiang)相通。這樣(yàng)，凹槽ABCDEA也就(jiù)組成一個(gè)“∞” 形的密封(fēng)空間(如采(cai)用單頭螺(luo)紋，則凹槽(cáo)将順軸向(xiàng)盤饒螺杆(gǎn)，将吸排口(kou)貫通，無法(fǎ)形成密封(feng))。不難想象(xiàng)，在這樣的(de)螺杆 上，将(jiang)形成許多(duo)個獨立的(de)“∞”形密封空(kong)間，每一個(ge)密封空間(jian)所占有的(de)軸向長度(du)恰好等于(yú)累杆的導(dao)程t。因此，為(wei)了使螺杆(gan)能吸、排油(you)口分隔開(kai)來，螺杆的(de)螺紋段的(de)長度至少(shǎo)要大于一(yī)個導程。Due to the mutual engagement of each screw and screw and the close coordination of the liner wall, between the inlet and outlet of the pump, can be divided into one or more of the sealed space.With the rotation of the screw and the meshing, the sealed space in pump suction side form unceasingly, the liquid from the suction chamber seal in among them, and the suction chamber along the screw axial continuously goes on to the discharge end, will be closed in the space of the liquid discharge, like a nut in screw rotation being constantly move forward, the screw thread turns as liquid, when screw rotating screw rotation is equivalent to the liquid in the inside of the screw pump, this is the basic work principle of screw pump.The sealing surface between screw and shell is a space curved surface.Exist on the surface of the sealing section, such as ab or DE and screw groove part of the form many the gap of the triangle ABC, def.These triangular gap formation fluid channels, make active screw groove with A driven screw groove on the connected to B and C.And groove B, C and along their spiral around to the back, and, respectively, and on the back of the groove connected to D and E.Due to the tank D, E and F (it belongs to another head spiral) of corresponding seal surface, there are also similar to the positive triangle gap a 'b' c ', so D, F, E will also is same.So, grooves ABCDEA on forming a "up" form of the sealed space (such as using single thread, axial disc groove will arrange spare screw, connecting the suction PaiKou, unable to form a seal).It is not hard to imagine that in this kind of screw, will form a number of independent "up" form sealed space, each of the sealed space occupied the axial length equals the tired stem lead t.Therefore, in order to make the screw suction and discharge of oil can be separated, the length of the screw thread of at least than a lead.