In order to explain the working principle of the diesel pump, a bolt can be used as a metaphor. When the bolt turns and the nut turns, the nut will produce axial movement. Screw pump and bolt to pay back when similar at work, as the thread of cell liquid liquid "nut", is the "liquid nut, also can produce axial movement, but only one screw is short of objective, 'because of liquid liquid, and thread slot is well versed in, the form is a sealed space, reach the purpose of conveying fluid. At most, it can be used as a conveyor for conveying solid solution or granular powder objects. However, a thin rack 2 is used between screw 1 and pump body 3 to engage the screw, as shown in FIG. 30. In this way, the thread slots of the screw are separated by the rack into sealed Spaces. When the screw rotates, with the thread groove and rack moving forward, the oil can be sucked from one end of the screw, sent to the other end of the screw discharge. It's like a piston moving forward forever, pressing out the oil in the pump cylinder. For the pump to work continuously, the rack would have to be made infinitely long, which is virtually impossible, because it moves forward all the time. So the actual screw pump is to use a driven screw instead of an infinite rack.
The high-pressure diesel pump works according to the above principle. FIG. 30 shows the structure of lB-B series oil pump with working pressure of 2.45 mpa (25 kg · force/cm ") and displacement of 8-100 L/min. In the pump body 2 is equipped with three parallel double head screw, the middle is a thick active convex screw 3, it is driven by the prime mover rotation, in the active screw on both sides of each has a thinner driven concave screw 4 and it meshing. A number of sealing chambers are formed between the meshing three screws and the pump, and the oil is inhaled from the left end of the pump body and discharged from the right end of the pump body.
Figure 30
