A Ceramic Flat Slide Valve for Hydraulic Applications

With a flat slide valve concept, a reduction in leakage and an increase in service life could be achieved compared to conventional piston spool valves. In order to achieve a reduction in leakage flows and guarantee the adjustability of the valves at the same time, a correct design of the pressure compensation is essential. The level of force depends on the operating point of the valve and the position of the slider. Due to the design of the flat slide valve, it is possible to use ceramic semi-finished products for the main stage, which consists of control plates and a slide plate. The geometries are simple enough to be inexpensively manufactured with sufficient accuracy from a ceramic pre-product using laser cutting technology. High-tech ceramics are a promising material, which can contribute to an improvement of the performance of the valves. The higher resistance of ceramic materials to abrasive wear further increases the service life of the valves. Furthermore, ceramic materials show lower friction coefficients compared to metallic materials, which is of great importance for the concept of the flat slide valve due to the sliding of the plates on top of each other. However, at the same time the use of ceramics, which are rarely used in hydraulics at the moment, means that the design must be appropriate to the material and must be taken into account when designing the main valve stage. This article presents the concept of the flat slide valve for a proportional 4/3-way valve. Therefore, the design of the pressure compensation is shown and the current design of the main valve stage is presented. This includes the design of the flow channels, which has to be suitable for ceramic materials. The preliminary design of the flow channels were executed with CFD-simulations. With the shown design the function of a 4/3-way valve, known from piston spool valves, can be implemented with a linear behavior between slide plate deflection and opening cross section.