The basic working principle of an electro hydraulic system is to switch hydraulic energy from an electrical signal to an equivalent mechanical energy. The process of switching hydraulic energy from one source to another is known as a hydraulic control valve. The hydraulic control valve continuously controls the output pressure and flow, as well as the displacement and acceleration of the actuator. The hydraulic control valve has a fast dynamic response and is widely used in high-speed mechanical equipments.
The electrical and hydraulic part of an electro hydraulic cylinder has both an electrical and a proximity sensor. Another part of the system is a time-delay relay. It delays certain work operations by setting a preset delay time. There are two basic types of timer: an On-delay timer, which delays work operations for t seconds, and an Off-delay timer, which brings the contacts back to their original positions when the coil is de-energized.
The working principle of an electro hydraulic system can be described by the nonlinear state space of a below-fourth order circuit. Logic controls can start or stop the hydraulic system. They operate using an AND or an OR function, where the AND function produces an output when all inputs are present. The OR function, on the other hand, produces an output when any one of the inputs is absent or not present. The latter type of sensor is more common in electro-hydraulic systems, and is more widely used in vehicles.