Load simulation -: An effective tool for testing hydraulic valves

Fluid power components are generally designed for use in a variety of systems where the dynamic and static properties vary over a broad range. The development process usually entails an extensive amount of verifying laboratory tests. However, it is difficult to predict the interaction between the component and the system by means of ordinary laboratory tests. Expensive and time consuming full-scale tests are therefore also used in the development of new components. In previous studies by the authors of this paper, a load simulator for testing fluid power valves has been developed and analysed. The simulator is based on a technique referred to as "hardware-in-the-loop-simulation" and enables the test valve to be connected to a simulated load system. This makes it possible to study the interaction between the test object and various systems as the simulated load system easily can be changed, thus reducing time as well as cost. An additional advantage is that the load simulator mimics both the steady state and dynamic characteristics of the load system. In this paper the simulator has been used to test a mobile fluid power control valve. The used test valve is equipped with an internal load sensing by-pass valve as well as pressure compensation of the meter-in orifice. A computer model of a cylinder with an inertia load has been used as load system. A number of different tests are performed showing that the simulator is a useful tool for assessing the valve performance. Several of the these tests are difficult to accomplish using ordinary test methods. The tests shows that the simulator can handle different types of tests as well as different load system without altering the hardware set-up.