Hydraulic systems are very common in the industry and other technical fields. The most used control valves are sliding directional control valves, which have no seals on the control pistons. This leads to internal leakage. The stability of the leakage is strongly dependent on the purity of the hydraulic fluid. The work deals with the influence of the purity of the hydraulic oil on the service life and volumetric efficiency of the sliding directional control valve considered. As part of the work, a hydraulic test bench was designed and set up on which three service life tests of a hydraulic 4/3 directional control valve were performed. For each test, a different amount of the MTD test powder recommended for accelerated tests was added to the hydraulic oil. The valve was cycled at a frequency of 4 Hz until 2 million cycles were reached. At the valve, the internal leakage of the A and B lines was measured using two graduated cylinders and a stopwatch. After the tests were performed, the housings were cut open and the sliding surfaces of the housings and pistons of the tested valves were examined for wear. The research shows that as the amount of MTD test powder in the hydraulic fluid increases, the wear of the surfaces inside the valve increases visibly, which is seen as an increase in valve internal leakage.
|
