由(yóu)于各螺杆的(de)相互齧合以(yi)及螺杆與襯(chen)筒内壁的緊(jin)密配合，在泵(beng)的吸入口和(hé)排出口之間(jian)，就會被分隔(gé)成一個或多(duō)個密封空間(jian)。随着螺杆的(de)轉動和齧合(hé)，這些密封空(kōng)間在泵的吸(xī)入端不斷形(xíng)成，将吸入室(shi)中的液體封(fēng)入其中，并自(zi)吸入室沿螺(luó)杆軸向連續(xù)地推移至排(pái)出端，将封閉(bì)在 各空間中(zhōng)的液體不斷(duàn)排出，猶如一(yī)螺母在螺紋(wen)回轉時被不(bú)斷向前推進(jin)的情形那樣(yàng)，其中螺紋圈(quān)數看做液體(ti)，當螺釘旋轉(zhuǎn)時螺紋在轉(zhuǎn)動時就相當(dang)于液體在螺(luo)杆泵裡面的(de)情形，這就是(shì)螺杆泵的基(jī)本工作原理(lǐ)。螺杆與殼體(ti)之間的密封(feng)面是一個空(kong)間曲面。在這(zhè)個曲面上存(cún)在着諸如ab或(huò)de之類的非密(mì)封區，并且與(yu)螺杆的凹槽(cáo)部分形成許(xǔ)多三角形的(de)缺口abc、def。這些三(san)角形 的缺口(kǒu)構成液體的(de)通道，使主動(dong)螺杆凹槽A與(yǔ)從動螺杆上(shàng)的凹槽B、C相連(lián)通。而凹槽B、C又(yòu)沿着自己的(de)螺線繞向背(bèi)面， 并分别和(he)背面的凹槽(cao)D、E相連通。由于(yú)在槽D、E與槽F(它(ta)屬于另一頭(tóu)螺線)相銜接(jiē)的密封面上(shang)，也存在着類(lei)似于正面的(de)三角形缺口(kǒu)a’b’c’，所以D、F、E也将相(xiang)通。這樣，凹槽(cao)ABCDEA也就組成一(yī)個“∞” 形的密封(feng)空間(如采用(yòng)單頭螺紋，則(ze)凹槽将順軸(zhóu)向盤饒螺杆(gan)，将吸排口貫(guan)通，無法形成(cheng)密封)。不難想(xiǎng)象，在這樣的(de)螺杆 上，将形(xing)成許多個獨(du)立的“∞”形密封(fēng)空間，每一個(ge)密封空間所(suo)占有的軸向(xiàng)長度恰好等(děng)于累杆的導(dǎo)程t。因此，為了(le)使螺杆能吸(xi)、排油口分隔(ge)開來，螺杆的(de)螺紋段的長(zhǎng)度至少要大(dà)于一個導程(cheng)。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.