Abstract
One way to realize inertia in energy saving hydraulic switching converters is a mechanical oscillator connected to a piston. Its two basic advantages over the use of fluid in an inductance pipe are higher compactness and a better decoupling of inductance and capacitance; these are opposed by a more complex valve system, which raises costs if electric control is applied. This paper presents and studies an oscillating mass converter with pure hydraulic control. It features a pressure control function and constitutes a step-up converter. A simple model is established to elucidate the basic properties of the function principle under idealized conditions. The complete system with the hydraulic control concept is studied by an elaborate dynamical model. It is shown that the converter is able to operate in the intended way under the conditions of the mathematical model. A potential application for a load sensing type meter out control of a cylinder drive is sketched.
Highlights
Switching methods are widely used in electrical engineering for an energy efficient control of motors, DC or AC voltage supply units, or magnets
The historically oldest application of an energy efficient switching control is Montgolfier’s hydraulic ram from 1796 [1]. Despite this historical lead role of hydraulics, the systematic study of switching controls in modern hydraulics started after the overwhelming success of this technology in electrical engineering became apparent and had the clear target to enable control without throttling and in a simpler way than with hydraulic transformers based on displacement machines
This paper presents a concept and an analysis by mathematical modeling and simulation of an oscillating mass converter (OMC) which employs pure hydraulic means for operation to overcome these cost and supply problems
Summary
Switching methods are widely used in electrical engineering for an energy efficient control of motors, DC or AC voltage supply units, or magnets. With the objective to realize high switching frequencies and large flow rates, several groups tested rotary valves [20,21] Such valves are bulky, costly and not merchantable, do not solve the cost and availability problem. Its operating principle is a step-up converter since it transmits part of the incoming fluid to a high-pressure port (system pressure pP) This converter can accomplish flow control if the actual flow rate is transformed into a pressure, e.g., by an orifice, which is compared to a reference pressure. This is a first feasibility study to find out if simple hydraulic concepts can provide high enough switching frequencies on the one hand and an acceptable control performance on the other hand
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