2024 Volume 17 Issue 1 Pages 10-21
In construction machinery that heavily relies on hydraulic systems, the efficiency of hydraulic components plays a crucial role in the machine's overall energy efficiency. The piston rings in the bent-axis-type axial piston motor used in construction machinery prevent oil leakage but reduce mechanical efficiency due to friction. This study conducted friction force measurements and mixed lubrication analysis to understand the friction characteristics of piston rings in a bent-axis-type axial piston hydraulic motor. The test rig, capable of applying hydraulic pressure and reciprocating motion, was utilized for these measurements. Friction force was assessed in relation to hydraulic pressure and reciprocating speed using this test rig. Additionally, the impact of altering the number of piston rings from one to two was examined. The study also measured changes in friction force when the position of the apex of the piston ring sliding surface was altered. Findings indicated that the piston rings of the bent-axis-type axial piston motor were in a mixed lubrication state, where solid contact occurred. Furthermore, friction force was primarily influenced by pressure and negligibly affected by rotational speed. Moreover, the total friction force remained almost unaffected by the number of piston rings. This suggests that the presence of only one piston ring increases the load per ring, potentially shortening the piston ring's lifespan. The position of the apex of the sliding surface of the piston ring alters the friction force by changing the pressure distribution between the piston ring and the cylinder bore wall. The results from the mixed lubrication analysis qualitatively aligned with the measured outcomes.
