FESTO proportional valve simple explanation

FESTO proportional valveSimple explanation: Load sensing and pressure compensation technology for electro-hydraulic proportional multi way valve; Saving energy, reducing oil temperature, and improving control accuracy, while also ensuring that the synchronous action of several executing components does not interfere with each other during movement, load sensing and pressure compensation technology are now widely used in construction machinery. Load sensing and pressure compensation are very similar concepts, both of which use pressure changes caused by load changes to regulate pump or valve pressure and flow to meet system operating requirements. For a quantitative pump system, load sensing refers to directing the load pressure load sensing oil circuit to a remote pressure regulating relief valve. When the load is small, the relief valve's set pressure is also small; The load is large and the set pressure is also high, but there is always a certain overflow loss. The variable pump system introduces the load sensing oil circuit into the pump variable mechanism, so that the pump output pressure increases with the increase of load pressure (always a small fixed pressure difference), making the pump output flow equal to the actual required flow of the system, without overflow loss, and achieving energy saving. FESTO proportional valve, also known as distribution valve, is one of the most basic components of mobile mechanical hydraulic systems. It is a composite valve that can achieve direction and flow regulation. Due to manufacturing cost considerations and low precision requirements for engineering machinery control, displacement sensing sensors are generally not installed in proportional multi way valves, which have electronic detection and error correction functions. The displacement of the valve core is easily affected by pressure fluctuations caused by load changes, and visual observation is necessary to ensure the completion of the operation. Attention should be paid to external interference during electronic and remote control operations. Recently, with the development of electronic technology, more and more people are using displacement sensors such as internal differential transformers (LDVT) to detect the movement of valve cores, achieving closed-loop control of valve core displacement. The electro-hydraulic slide valve proportional multi way valve is an ideal electro-hydraulic conversion control component. It retains the basic functions of a manual multi way valve and also adds control methods such as position electric feedback proportional servo operation and load sensing. It is a replacement product for engineering machinery distribution valves. This highly integrated proportional valve consists of an electromagnetic proportional valve, a position feedback sensor, a driver amplifier, and other electronic circuits. It has a certain correction function and can effectively overcome the shortcomings of general proportional valves, greatly improving control accuracy.
FESTO Proportional Valve Technical Parameters
FESTO proportional valves can provide multiple flow levels (variable valve port size). By setting different pressure compensations and generating corresponding flow levels, a wide range of flow current control curves can be achieved.
Maintain a fixed pressure difference before and after the FESTO proportional valve (variable valve port size), and maintain a fixed flow rate regardless of changes in pre valve pressure or post valve load.
The fixed pressure difference on the proportional valve limits the hydraulic force acting on the valve core. If there is no pressure compensation, the electromagnetic force and spring force will not be able to maintain the operation of the valve under high flow and high pressure conditions.
A typical circuit uses proportional flow control valves, combined with limiting or priority pressure compensators, to control the speed of hydraulic motors or cylinders.
FESTO proportional valve is a three-way plug-in valve. Regardless of the flow rate and pressure of the system (within the limits of the valve), it can provide controlled output pressure under the action of current. Direct acting proportional pressure relief valves can be used in low flow situations.
The main valve of FESTO electric proportional valve in Germany is controlled by the output pressure of the pre stage valve, and the pressure of the pre stage valve comes from the inlet p of the servo valve. If the pressure at port p is insufficient, the pre stage valve cannot output enough pressure to push the main valve core to move.FESTO proportional valveBriefly explain; Proportional valves actually have many disadvantages, such as high energy consumption and waste, easy failure, poor anti pollution ability, high price, etc. The only benefit is that their dynamic performance is the highest among all hydraulic valves. With this advantage, servo valves have to be used in many situations that require high dynamic characteristics, such as servo control of aircraft rockets, turbine speed regulation, and so on.
When the load of FESTO electrical proportional valve is zero, if the four-way slide valve * is opened, the p-port pressure=t-port pressure+valve port pressure loss (ignoring other pressure losses on the oil circuit). If the valve port pressure loss is very small and the t-port pressure is zero, then the p-port pressure is not enough to supply the front stage valve to push the main spool, and the entire servo valve fails. So the valve port of the servo valve is made too small, even when the valve port is fully open, there must be a certain pressure loss to maintain the normal operation of the pre stage valve.
FESTO Electrical Proportional Valve Instructions VPPE-3-1-1/8-6-010-E1 has three pressure ranges for setting. In the equilibrium state, the gas consumption is 0. In the unpressurized state, zero position adjustment and full position adjustment can be performed. If the power is cut off under pressure, the output pressure can be temporarily maintained unchanged. There are two monitoring methods (analog output, switch output) to choose from.