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David RichardsonResearch AssistantAnalysis of Axial Piston Pump Lubrication & DynamicsNovember 14, 2013Mechanical Engineering Tribology Laboratory (METL)#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)1OutlineMotivation & ObjectivesBackgroundPressure Profiles & CavitationAdams Kinematic ModelAux Cam ForcesContact ForcesComponent Interference

#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Motivation and ObjectivesComponents within an Axial Piston Pump have shown signs of abnormal contact and wear causing damage and sharp temperature risesAbnormal wear occur on the port plate of the pump as well as between the cam plate and the shoesThe objective of this research is to investigate and model the dynamics of the axial piston pump port plate and cam plateCavitation is the major cause of wear on the port plateThe geometric tolerances of the cam plate affect the performance and forces that act on it#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Axial Piston Pump-BackgroundThe cam plate at the bottom of the piston was modeled using Adams

Previous work has modeled the port plate using fluent showing cavitation in the transition regions from low to high pressure

Cam PlateShoeShoe Pocket

Cavitation

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ShoePort PlateCam Plate6[1] www.hydraulic-pump.info#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Pressure Profiles &Cavitation

Pressure profiles were created for a step and inclined slider bearingThe model was used as the basis to include cavitation

Cavitation was then applied to a bearing with circular pockets

The model could possibly be applied to the geometry of a port plate

#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Adams Kinematic Cam Plate Model

Adams was used to create a rigid body dynamic model and the forces were measured at the contact between the shoe and cam plate3 different cam plate geometries (A,B,C) and 3 different angles (19.0o, 9.5o,0.1o) were tested on the pump For the different geometries, A was a perfectly dimensioned cam plate, B and C had mismatched dimensionsThe model was setup with a steady rotational velocity of the block50 rpm was used for numerical stability higher speeds cause the solution to diverge

#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Contact Forces

Hanger Angle EffectsAt high angles the shoes contact the cam plate for only a short period of timeClear, discrete spikes occur once per revolution A handoff occurs between consecutive pistons with some overlapAt low angles the shoes remain in contact for a longer period of timeThe handoff between shoes is smoother due to the lower elliptic path of the shoes

-Shoe Path-Cam Plate 19.00.1Assembly A - 19.0Assembly A 0.1

#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)Component Interference

Assembly A Perfect Machine TolerancesAt high angles the shoes contact the cam plate for only a short period of timeClear, discrete spikes occur once per revolution and only one shoe is in contact at a timeAssembly C Mismatched Shoe/Block/Cam Plate DimensionsWith mismatched dimensions, two shoes will contact the cam plate simultaneously causing kicking to occurContact occurs with pistons on opposite sides of the plate

Assembly C - 19.0Assembly A 19.0#November 14, 2013Mechanical Engineering Tribology Laboratory (METL)