Principle servo pump -
speed control for hydraulic pumps. In industrial oil hydraulic applications, pumps are typically operated on the mains through asynchronous electric motors with a fixed speed.
BOY 35 E injection moulding machine with servo-motor pump drive
In this case, oil volumes and oil pressure are regulated through valves and/or adjustable pumps - whereby a high proportion of energy is delivered as heat within the system.
In connection with COMBIVERT F5 drive controllers, the assemblies can be varied in terms of speed so that oil volume and pressure are exactly regulated for the requirements of the machine. Requirements will differ depending on the application.
The simplest approach for energy optimisation consists of the cyclical lowering of speed in the partial load and idling range of the hydraulic system. Usually the existing asynchronous machine remains in the system. The encoderless motor control process developed by KEB - A.S.C.L. (Asynchronous Sensorless Closed Loop) - offers the best features in this context.
The main advantages for users can be summed up as reduced losses in the oil loop, which results in a smaller energy input and hence also a reduction in cooling output. At the same time, the drive system allows for the use a broad speed range when the machine is operated in the field weakening range and significantly reduces cycle times.
The range of applications offers even more potential for those who want to achieve even more:
The high-dynamic automatic pressure and volume control provided by the COMBIVERT F5 servo drive when operating synchronous servo motors also allows additional optimised drive profiles for the system, which creates additional savings effects.
The basic features of COMBIVERT F5 consist of the high control quality for synchronous machines and the PID controller for pressure control as an integrated component of the machine software.
Compared to the control of hydraulic systems with "variable pump", the version that includes a "fixed displacement pump" can significantly reduce noise levels and improve response times and repeat accuracies.
Pressure and volume controls are subject to additional requirements if several different hydraulic actors are regulated with the combination of motor and fixed displacement pump. This may be a typical scenario in the case of a plastic injection machine, where up to five different axles are moved alternately.
Specifically, these include the applications:
- injection (cylinder with large diameter)
- ejection (cylinder with small diameter) or
- plastification (hydraulic motor at the screw).
The PID controller in the KEB COMBIVERT F5 is also used for these applications, and the various control sections are adapted inside the device with one single pressure controller during the process. In this combination the KEB COMBIVERT F5 is successfully operating e.g. in the BOY 35E injection moulding machine.
In addition to pressure and volume control, KEB COMBIVERT F5 also features internal position control, which processes the signal of the hydraulic axle's position encoder for exact positioning of a movement.
The highest level of flexibility for all movement processes is achieved by combining the drive controllers with the KEB COMBICONTROL C6 control. A fully freely-programmable IEC 61131 interface and specially adapted controller modules are available for customised applications.
For the operation of speed-controlled hydraulic pumps, take advantage of more than 10 years of application advisory services and more than 100,000 systems in the field.