由(you)于各螺(luó)杆的相(xiàng)互齧合(hé)以及螺(luo)杆與襯(chen)筒内壁(bi)的緊密(mì)配合，在(zai)泵的吸(xī)入口和(hé)排出口(kou)之間，就(jiù)會被分(fen)隔成一(yī)個或多(duo)個密封(feng)空間。随(suí)着螺杆(gǎn)的轉動(dong)和齧合(hé)，這些密(mi)封空間(jian)在泵的(de)吸入端(duan)不斷形(xing)成，将吸(xī)入室中(zhong)的液體(tǐ)封入其(qí)中，并自(zi)吸入室(shi)沿螺杆(gǎn)軸向連(lian)續地推(tuī)移至排(pái)出端，将(jiang)封閉在(zài) 各空間(jian)中的液(ye)體不斷(duàn)排出，猶(yóu)如一螺(luó)母在螺(luó)紋回轉(zhuǎn)時被不(bu)斷向前(qian)推進的(de)情形那(na)樣，其中(zhōng)螺紋圈(quān)數看做(zuò)液體，當(dang)螺釘旋(xuán)轉時螺(luo)紋在轉(zhuan)動時就(jiu)相當于(yú)液體在(zài)螺杆泵(bèng)裡面的(de)情形，這(zhe)就是螺(luo)杆泵的(de)基本工(gong)作原理(lǐ)。螺杆與(yǔ)殼體之(zhī)間的密(mi)封面是(shì)一個空(kōng)間曲面(miàn)。在這個(gè)曲面上(shang)存在着(zhe)諸如ab或(huo)de之類的(de)非密封(feng)區，并且(qie)與螺杆(gan)的凹槽(cao)部分形(xíng)成許多(duō)三角形(xing)的缺口(kǒu)abc、def。這些三(san)角形 的(de)缺口構(gou)成液體(ti)的通道(dao)，使主動(dòng)螺杆凹(āo)槽A與從(cong)動螺杆(gan)上的凹(āo)槽B、C相連(lián)通。而凹(ao)槽B、C又沿(yan)着自己(ji)的螺線(xian)繞向背(bei)面， 并分(fen)别和背(bei)面的凹(ao)槽D、E相連(lian)通。由于(yu)在槽D、E與(yǔ)槽F(它屬(shu)于另一(yi)頭螺線(xiàn))相銜接(jiē)的密封(feng)面上，也(ye)存在着(zhe)類似于(yú)正面的(de)三角形(xíng)缺口a’b’c’，所(suǒ)以D、F、E也将(jiāng)相通。這(zhe)樣，凹槽(cao)ABCDEA也就組(zǔ)成一個(gè)“∞” 形的密(mi)封空間(jian)(如采用(yòng)單頭螺(luó)紋，則凹(āo)槽将順(shùn)軸向盤(pán)饒螺杆(gan)，将吸排(pái)口貫通(tōng)，無法形(xing)成密封(fēng))。不難想(xiang)象，在這(zhe)樣的螺(luó)杆 上，将(jiāng)形成許(xu)多個獨(dú)立的“∞”形(xing)密封空(kong)間，每一(yi)個密封(fēng)空間所(suǒ)占有的(de)軸向長(zhang)度恰好(hao)等于累(lèi)杆的導(dǎo)程t。因此(cǐ)，為了使(shi)螺杆能(neng)吸、排油(yóu)口分隔(gé)開來，螺(luó)杆的螺(luo)紋段的(de)長度至(zhì)少要大(da)于一個(gè)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.