由于各螺杆的相互齧合以及螺杆與(yǔ)襯筒(tǒng)内壁(bì)的緊(jǐn)密配合，在泵的(de)吸入(rù)口和排出(chū)口之(zhī)間，就會被(bèi)分隔成一個或(huò)多個密封空間(jiān)。随着螺杆(gǎn)的轉動和齧合，這些(xiē)密封空(kōng)間在泵的吸入(rù)端不斷(duàn)形成，将(jiāng)吸入室中的(de)液體(tǐ)封入(rù)其中(zhōng)，并(bìng)自吸入(rù)室沿(yán)螺杆軸向(xiàng)連續地推移至(zhì)排出(chū)端，将封(fēng)閉(bì)在 各空間(jiān)中的液體(tǐ)不(bú)斷(duàn)排出(chū)，猶如一(yī)螺母在(zài)螺紋回轉時被(bèi)不斷向前推進(jìn)的情形那樣，其(qí)中螺紋(wén)圈數看做液體，當螺釘旋轉時螺紋在(zài)轉動時就(jiù)相(xiàng)當(dāng)于液體在(zài)螺杆(gǎn)泵裡面(miàn)的(de)情形(xíng)，這就是螺杆泵(bèng)的基(jī)本工作原(yuán)理。螺杆與殼體(tǐ)之間(jiān)的密封面是一個空間曲(qǔ)面。在這個曲面(miàn)上存(cún)在着諸如(rú)ab或de之類的(de)非(fēi)密(mì)封區，并(bìng)且(qiě)與螺杆的(de)凹槽部分(fèn)形成許(xǔ)多三角形(xíng)的缺口abc、def。這些(xiē)三角形 的缺口構成液(yè)體(tǐ)的通(tōng)道，使主(zhǔ)動螺杆(gǎn)凹槽(cáo)a與從(cóng)動螺(luó)杆(gǎn)上的凹槽b、c相(xiàng)連通(tōng)。而凹(āo)槽b、c又(yòu)沿着自(zì)己的螺(luó)線繞(rào)向背面， 并分别(bié)和背面的(de)凹槽d、e相(xiàng)連通。由(yóu)于在槽d、e與槽f(它(tā)屬于另一頭螺(luó)線)相銜接的密封面(miàn)上，也存在(zài)着(zhe)類似于(yú)正面(miàn)的三(sān)角形缺(quē)口a’b’c’，所以d、f、e也将(jiāng)相通。這樣(yàng)，凹槽abcdea也就(jiù)組成(chéng)一個“∞” 形的密封(fēng)空間(如采(cǎi)用單頭螺紋(wén)，則(zé)凹槽将(jiāng)順(shùn)軸向(xiàng)盤饒螺(luó)杆(gǎn)，将吸排口(kǒu)貫(guàn)通，無法形成密封(fēng))。不難(nán)想象，在這樣的(de)螺杆 上，将(jiāng)形成(chéng)許多個獨立的(de)“∞”形密封空間，每(měi)一個密封(fēng)空間(jiān)所占(zhàn)有的(de)軸向長度恰好等于(yú)累杆的導(dǎo)程t。因(yīn)此，為(wéi)了(le)使螺杆(gǎn)能吸、排(pái)油口分(fèn)隔開來(lái)，螺杆的螺紋(wén)段的長度(dù)至少要大于一(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.