The system shown below represents? A. A Closed-loop control system using a stroke-controlled proportional valve. B. A Closed-loop control system using a force-controlled proportional valve. C. An open-loop control system using a force-controlled proportional valve. D. An open-loop control system using a stroke-controlled proportional valve

Electro hydraulic Seminar. Well attended by a great group of industry professional

As shown in the figure, based on the hardware configuration, control electronics are classified as follows: Panel Mounted Control electronics: Panel Mounted ECUs are referred to as Control Cards. They are kept apart from the valve in a conditioned and guarded cabinet. The front panel, as shown in the figure, gives access to the end user to tune the functions contained in the ECU. Modular Control Electronics: Modular ECUs are contained inside a customized enclosure. It can be used for industrial/mobile applications. It can be used to control a single valve or a multi-axis system. Integrated Control Electronics: Integrated Control Electronics are referred to as Onboard Electronics (OBE). Using this configuration results in a compact system, reduced wiring effort, and ease of network interfacing. There are performance limitations at high temperature (good for T < 60 OC).

Sorry for not getting back to you - still relaxing on the North Cost of Egypt

As a matter of fact, hydraulic systems are known as systems of higher power density and less energy density as compared to the electrical systems. In order to get better understanding of these terms, look at Fig. 1.10. The figure shows, on the upper part of it, a comparison between a hydraulic motor and an electric motor that has the same power capacity. The electric motor has ten times the weight and size of the hydraulic motor. This means that the hydraulic motor has a higher power/weight ratio. Power/Weight Ratio is also referred as Specific Power or Power Density. This property is very important for mobile machines since it affects directly the compactness of the machine. The higher the value of the power density the more compact the machine. That justifies the wide use of hydraulic systems for earth moving machines and the aerospace industry. To understand this property from another angle let us compare hydraulic motors and electric motors of the same size as shown in the lower part of Fig. 1.10. The figure shows that a hydraulic motor receiving pressurized fluid with pressure of 300 psi, can produce the same amount of power as an electric motor of the same size. The average working fluid pressure in commercial hydraulic systems is 3000 psi. This means that a hydraulic motor can have ten times the power capacity of an electric motor of the same size. The term Energy Density refers to the ability to store energy. Energy can be stored in a hydraulic system by storing a volume of fluid under pressure of a gas in an element called accumulator. The value of the energy that can be stored in an accumulator is limited by the volume of the accumulator and the maximum pressure of the compressed gas in the accumulator. So, energy that can be stored in accumulators is limited in value as compared to the value of energy that can be stored in electrical systems in batteries.

Chapter 1 - Lesson 5C