Atsushi Yuge

Seizure Tests to Select Materials for Cylinder Blocks and Valve Plates in Water Hydraulic Pumps

For application to water hydraulic pumps (axial piston type), influence of material combination and micro shapes of sliding surfaces on friction and seizure were experimentally investigated. Seizure tests under water lubricating condition were carried out by an end-face sliding test apparatus, and sliding pairs containing diamond-like carbon (DLC) coating which is considered one of hopeful materials by its excellent tribological property in water were prepared for the seizure tests. As a result of the seizure tests it is obtained that in combination of stainless steel and DLC coating critical contact pressure on occurrence of seizure increases with increase of radius of pads edge of a stationary specimen. On the other hand, a result of the tests shows that combination of aluminium bronze and DLC coating has much higher critical contact pressure on occurrence of seizure than combination of stainless steel and DLC when micro shapes of sliding surfaces are similar. For application of DLC coatings to valve plates in water hydraulic pumps it is better to choose copper alloys as mating surfaces of DLC coating and it is required to round edges of pads on valve plates adequately.

Prediction Calculation of the Cavitation Erosion Generated in Connection With a High-Pressure Jet

High-pressure jets are being pursued in diesel engines in order to facilitate development of next-generation fuel injection systems aiming at high performance, high fuel economy, and low emissions of smoke. Cavitation erosion accompanying the use of high-pressure jets for diesel fuel injection pumps is a factor responsible for reduced equipment durability and performance. In response, the project reported here involved the production of test equipment for the purpose of replicating the behavior of a fuel injection pump as it would occur in an actual diesel engine, with erosion testing, and analysis of the shock pressure by the cavitation, and its generating part. As a result, the following behaviors were noted. (1) In the 3-dimensional analysis of an unsteady cavitation jet stream, the shock pressure by the cavitation and its generating part can be predicted. (2) If the exit clearance of a hole is adjusted, the generating position of a erosion is controllable.Copyright