Variable displacement pumps are pumps with variable displacement. Variable displacement pumps can be single-acting vane pumps, radial piston pumps, or axial piston pumps, and are widely used in hydraulic transmission fields such as metallurgy, mining, construction machinery, ships, and civil aviation ground equipment.
Variable displacement pump radial piston pump includes piston eccentric type and shaft eccentric type, axial piston type includes swash plate type and inclined shaft type.
Advantages and disadvantages
The axial piston pump works by using the volume change generated by the reciprocating movement of the piston parallel to the drive shaft in the piston hole. Since both the plunger and the plunger hole are round parts, they can achieve high precision matching during processing, so the volumetric efficiency is high, the operation is stable, the flow uniformity is good, the noise is low, and the working pressure is high. It is more sensitive, the structure is more complex, and the cost is higher.
Application of variable pump system
The transformation of the hydraulic system of the injection molding machine from valve control to pump control has been realized, the conventional throttle speed control system has been transformed into a proportional speed control system, and the control performance indicators of the whole machine have been newly improved and improved. Specifically, the proportional variable pump system has the following advantages in addition to the advantages of the conventional proportional control system:
- For machines with the same power, the injection speed can be increased by more than 25%, which is more suitable for thin-walled precision injection requirements. Since the power calculation of the ordinary PQ system is based on the pressure-holding state, the power consumption of the proportional variable pump system is very low during this action, so the displacement of the oil pump can be increased by more than 25%;
- The heating of the system is reduced, and the service life of the hydraulic components is prolonged. The proportional variable system has almost no throttling and overflow losses, and the heat generation is greatly reduced when the system is running. Not only can the consumption of cooling water be saved, but the low oil temperature can greatly improve the life of sealing components;
- Reduced energy consumption and improved system efficiency;
- It can realize the control of numerical control proportional back pressure, and the plasticizing effect has been improved;
- The pollution level of the hydraulic system is reduced, the system failure is significantly reduced, the motion stability is greatly improved, and the hydraulic oil service time is more than 3 years longer than that of the conventional system.
The proportional variable pump system has good self-adaptability, and its output pressure and flow can be consistent with the load demand, which solves the problems of flow incompatibility and pressure incompatibility of the throttle speed control system, greatly reducing energy loss, and improving system efficiency. The energy-saving effect is very obvious. Compared with the ordinary quantitative pump + PQ proportional valve system, it can save 25-45% of electricity.