由(you)于各螺杆的相(xiang)互齧合以及螺(luo)杆與襯筒内壁(bì)的緊密配合，在(zài)泵的吸入口和(hé)排出口之間，就(jiu)會被分隔成一(yi)個或多個密封(fēng)空間。随着螺杆(gǎn)的轉動和齧合(hé)，這些密封空間(jiān)在泵的吸入端(duān)不斷形成，将吸(xi)入室中的液體(tǐ)封入其中，并自(zì)吸入室沿螺杆(gan)軸向連續地推(tuī)移至排出端，将(jiang)封閉在 各空間(jiān)中的液體不斷(duan)排出，猶如一螺(luó)母在螺紋回轉(zhuǎn)時被不斷向前(qian)推進的情形那(na)樣，其中螺紋圈(quān)數看做液體，當(dang)螺釘旋轉時螺(luo)紋在轉動時就(jiù)相當于液體在(zai)螺杆泵裡面的(de)情形，這就是螺(luo)杆泵的基本工(gōng)作原理。螺杆與(yǔ)殼體之間的密(mì)封面是一個空(kōng)間曲面。在這個(ge)曲面上存在着(zhe)諸如ab或de之類的(de)非密封區，并且(qie)與螺杆的凹槽(cáo)部分形成許多(duō)三角形的缺口(kǒu)abc、def。這些三角形 的(de)缺口構成液體(tǐ)的通道，使主動(dong)螺杆凹槽A與從(cóng)動螺杆上的凹(ao)槽B、C相連通。而凹(āo)槽B、C又沿着自己(ji)的螺線繞向背(bèi)面， 并分别和背(bèi)面的凹槽D、E相連(lián)通。由于在槽D、E與(yǔ)槽F(它屬于另一(yī)頭螺線)相銜接(jie)的密封面上，也(ye)存在着類似于(yu)正面的三角形(xing)缺口a’b’c’，所以D、F、E也将(jiāng)相通。這樣，凹槽(cáo)ABCDEA也就組成一個(ge)“∞” 形的密封空間(jiān)(如采用單頭螺(luó)紋，則凹槽将順(shun)軸向盤饒螺杆(gan)，将吸排口貫通(tong)，無法形成密封(fēng))。不難想象，在這(zhè)樣的螺杆 上，将(jiang)形成許多個獨(du)立的“∞”形密封空(kong)間，每一個密封(feng)空間所占有的(de)軸向長度恰好(hǎo)等于累杆的導(dǎo)程t。因此，為了使(shi)螺杆能吸、排油(you)口分隔開來，螺(luó)杆的螺紋段的(de)長度至少要大(dà)于一個導程。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.