The Role of Geometrical Parameters in the Lubrication of the Swiss Lever Escapement

2021 ◽  
Vol 88 (6) ◽  
Author(s):  
Alejandro Roda-Buch ◽  
Valentine A. M. Magnin ◽  
Sandra Guadalupe Maldonado ◽  
Stefano Mischler
Keyword(s):  
Hydrodynamic Lubrication ◽  
Contact Forces ◽  
Geometrical Parameters ◽  
Inverse Dynamic ◽  
Technical Parameters ◽  
Lubrication Regimes ◽  
Multibody Model ◽  
Lubrication Regime ◽  
The Coefficient Of Friction

Abstract The lubrication regimes of a contact pair escapement-ruby pallet of a Swiss lever escapement have been investigated combining the theory of fluid lubrication with a well-established kinematic and inverse dynamic multibody model. The kinematic analytical results have been confronted with experimental measurements. The developed model allows to easily obtain, for the three operating phases of the Swiss lever escapement, the relative speed and the contact forces and, by considering a hydrodynamic lubrication regime, the lubricant minimum film thickness and the coefficient of friction. The presented formulation allows to study the influence of crucial technical parameters in the Swiss lever escapement lubrication. The spout radii of curvature have been identified as the optimal parameters to control the lubrication regimes in the pallet/escapement contacts. In that sense, an interesting result is that the lubrication regime moves away from the boundary lubrication by increasing these radii.

Direct Measurement of the Piston-Assembly Friction Force in a Single Cylinder Engine Under Motoring Conditions

2008 ◽  
Author(s):  
C. Fadel ◽  
N. G. Chalhoub ◽  
G. A. Kfoury ◽  
N. A. Henein
Keyword(s):  
Friction Force ◽  
Direct Measurement ◽  
Engine Speed ◽  
Hydrodynamic Lubrication ◽  
Test Rig ◽  
Oil Viscosity ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
The Coefficient Of Friction ◽  
Piston Assembly

Characterization of the lubrication regimes and quantification of the frictional losses are very important factors for the design of durable IC engines with improved fuel economy. Therefore, the current work has focused on the development of a tribology test rig that allows for the direct measurement of the instantaneous piston-assembly friction force under motoring conditions. The test rig was used to examine the effects of oil viscosity and engine speed on both the lubrication regimes and the friction force of the piston-assembly. Furthermore, the experimental data served to generate Stribeck curves for the coefficient of friction at different points in the cycle. Tear-down experiments were conducted to assess the friction contribution of each component in the piston-assembly. The results demonstrated that the magnitude of the friction force decreases with increasing oil grade under both boundary and mixed lubrication regimes. However, it tends to increase with increasing oil viscosity under a hydrodynamic lubrication regime. Moreover, the engine speed above which the hydrodynamic lubrication regime becomes prevalent at the midpoint of the stroke tends to decrease with increasing oil viscosity.

Analysis of the Contribution of Adhesion and Ploughing to Shoe-Floor Lubricated Friction in the Boundary Lubrication Regime

2011 ◽  
Author(s):  
Caitlin Moore ◽  
Kurt Beschorner ◽  
Pradeep L. Menezes ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Ambient Conditions ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Material Hardness ◽  
Lubrication Layer ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Pin On Disk

Slip and fall accidents cost billions of dollars each year. Shoe-floor-lubricant friction has been shown to follow the Stribeck effect, operating primarily in the boundary and mixed-lubrication regimes. Two of the most important factors believed to significantly contribute to shoe-floor-lubricant friction in the boundary lubrication regime are adhesion and ploughing. Experiments were conducted using a pin-on-disk tribometer to quantify adhesion and ploughing contributions to shoe-floor friction in dry and lubricated conditions. The coefficient of friction between three shoe materials and two floor materials of different hardness and roughness were considered. Experiments were conducted under six lubricants for a sliding speed of 0.01 m/sec at ambient conditions. It was found that the contribution of adhesion and ploughing to shoe-floor-lubricant friction was significantly affected by material hardness, roughness, and lubricant properties. Material hardness and roughness are known to affect adhesion, with increased hardness or increased roughness typically resulting in decreased adhesion. The smoothest shoe material, while also being the hardest, resulted in the greatest adhesional contribution to friction. The roughest material, while also being the softest, resulted in the lowest adhesional contributions under dry conditions. Canola oil consistently resulted in the lowest percent of full adhesion and water consistently resulted in the highest percent of full adhesion, presumably due to the thickness, of the boundary lubrication layer. Ploughing contribution was dependent upon the hardness of the shoe and floor materials. A positive correlation was found between the shoe and floor hardness ratio and ploughing coefficient of friction.

A New Approach to Determine Lubrication Regimes of Piston-Ring Assemblies

1997 ◽  
Vol 119 (4) ◽  
pp. 808-816 ◽  
Author(s):  
Naeim A. Henein ◽  
Shengqiang Huang ◽  
Walter Bryzik
Keyword(s):  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Spark Ignition Engine ◽  
Frictional Torque ◽  
New Approach ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
And Shifts

A new approach is developed to determine piston-ring assembly lubrication regimes from the instantaneous frictional torque measured for the whole engine. This is based on the variation of the friction coefficient with the duty parameter in the Stribeck diagram over the mixed and hydrodynamic lubrication regimes. The derived equation determines the lubrication regimes from the slope of the line in the Stribeck diagram. A single cylinder spark ignition engine was instrumented to determine the total instantaneous frictional torque of the engine. Experiments were conducted under different loads at a constant speed. Results show that the regime is mixed lubrication near the top dead center (TDC) and shifts to the hydrodynamic lubrication regime as the piston moves away from TDC. The extent of the mixed lubrication regime depends on engine load and speed.

scholarly journals Identification of Local Lubrication Regimes on Textured Surfaces by 3D Roughness Curvature Radius

2014 ◽  
Vol 966-967 ◽  
pp. 120-125 ◽  
Author(s):  
Cédric Hubert ◽  
Krzysztof J. Kubiak ◽  
Maxence Bigerelle ◽  
Laurent Dubar
Keyword(s):  
Hydrodynamic Lubrication ◽  
Contact Boundary ◽  
Curvature Radius ◽  
Textured Surfaces ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Cross Section Area ◽  
Strip Drawing ◽  
Mixed Lubrication Regime ◽  
Tribological Contact

This paper proposes a new method of 3D roughness peaks curvature radius calculation and its application to tribological contact analysis as a characteristic signature of tribological contact. This method is introduced through the classical approach of calculation of radius of asperity in 2D. Actually, the proposed approach provides a generalization of Nowicki's method [], depending on horizontal lines intercepting the studied profile. Here, the basic idea consists in intercepting the rough surface by a horizontal plane and to calculate the cross section area without including “islands into islands”, i.e. the small peaks enclosed in bigger ones. Then, taking into account the maximal value of the height amplitude of the roughness included into this area, an appropriate algorithm is proposed, without requiring the classical hypothesis of derivability, which may be unstable when applied to engineering surfaces. This methodology is validated on simulated surfaces, and applied to engineering surfaces created experimentally, with a laboratory aluminium strip drawing process. The regions of the textured and lubricated specimens surface are analysed, and the results gives interesting prospects to qualitatively identify the local lubrication regimes: regions with high curvature radii correspond to severe contact (boundary/mixed lubrication regime) while regions with low curvature radii correspond to hydrodynamic lubrication regime.

Tribological Evaluation for an In-Depth Understanding of Improved Workability of Foamed Asphalt

2019 ◽  
Vol 2673 (4) ◽  
pp. 533-545 ◽  
Author(s):  
Biswajit K. Bairgi ◽  
Umme A. Mannan ◽  
Rafiqul A. Tarefder
Keyword(s):  
Hydrodynamic Lubrication ◽  
Asphalt Binder ◽  
Chemical Properties ◽  
Frictional Resistance ◽  
Frictional Behavior ◽  
Lubrication Regimes ◽  
Foaming Process ◽  
Different Temperatures ◽  
The Coefficient Of Friction ◽  
Tribological Characterization

Asphalt binder acts as a lubricant between two aggregates during mixing and compaction. The frictional behavior of asphalt binder as a lubricant in an asphalt-aggregate system plays an important role in mixing and compaction (workability) of warm-mix asphalt (WMA). This study evaluates the frictional behavior of foamed WMA through tribological characterization using a ball-on-three-plates apparatus assembled inside a dynamic shear rheometer (DSR). The tribological test was conducted on six foamed asphalts with varying foaming water contents (FWCs) and on a controlled unfoamed asphalt binder at four different temperatures: 25°C, 60°C, 100°C, and 135°C. These binders were also characterized for rheological and chemical properties. Test results show that the foaming process alters the frictional resistance of the foamed asphalts; specifically, the foaming process reduces the coefficient of friction in elastohydrodynamic and hydrodynamic lubrication regimes. Reduced frictional resistance helps in the formation of a better coating during mixing and improves the sliding ability between aggregates during compaction at reduced temperature.

scholarly journals AN INVERSE DYNAMICS METHOD FOR RAILWAY VEHICLE SYSTEMS

Transport ◽  
2013 ◽  
Vol 29 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Tao Zhu ◽  
Shoune Xiao ◽  
Guangwu Yang ◽  
Weihua Ma ◽  
Zhixin Zhang
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Inverse Dynamics ◽  
Time History ◽  
Inverse Model ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Inverse Dynamic ◽  
Multibody Model ◽  
History Of

The wheel–rail action will obviously be increased during the vehicles in high-speed operation state. However, in many practical cases, direct measurement of the wheel–rail contact forces cannot be performed with traditional procedures and transducers. An inverse mathematical dynamic model for the estimation of wheel–rail contact forces from measured accelerations was developed. The inverse model is a non-iteration recurrence method to identify the time history of input excitation based on the dynamic programming equation. Furthermore, the method overcomes the weakness of large fluctuations which exist in current inverse techniques. Based on the inverse dynamic model, a high-speed vehicle multibody model with twenty-seven Degree of Freedoms (DOFs) is established. With the measured responses as input, the inverse vehicle model can not only identify the responses in other parts of vehicle, but also identify the vertical and lateral wheel–rail forces respectively. Results from the inverse model were compared with experiment data. In a more complex operating condition, the inverse model was also compared with results from simulations calculated by SIMPACK.

scholarly journals Advanced Tribological Characterization of DLC Coatings Produced by Ne-HiPIMS for the Application on the Piston Rings of Internal Combustion Engines

2021 ◽  
Vol 11 (21) ◽  
pp. 10498
Author(s):  
Alireza Vahidi ◽  
Diogo Fonseca ◽  
João Oliveira ◽  
Albano Cavaleiro ◽  
Amílcar Ramalho ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Hydrodynamic Lubrication ◽  
Research Work ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Combustion Engines ◽  
Piston Rings ◽  
Dlc Coatings ◽  
Lubrication Regimes ◽  
Lubrication Regime

Piston rings (PR) are known for almost a quarter of the friction losses in internal combustion engines. This research work aims to improve the tribological performance of PR by a recently developed variant of Diamond-like Carbon (DLC) coatings deposited in a mixture of Ar and Ne plasma atmosphere (Ne-DLC) by high-power impulse magnetron sputtering (HiPIMS). For the benchmark, the widely used Chromium Nitride (CrN) and DLCs deposited in pure Ar plasma atmosphere (Ar-DLC) were used. The tribological tests were performed on a block-on-ring configuration under different lubrication regimes by varying temperatures and sliding speeds. The analysis of the results was performed by Stribeck curves corresponding to each sample. An improvement of the tribological performance was observed for Ne-DLC films by up to 22.8% reduction in COF compared to CrN in the boundary lubrication regime, whereas, for the Ar-DLC film, this reduction was only 9.5%. Moreover, the Ne-DLC films achieved ultralow friction of less than 0.001 during the transition to a hydrodynamic lubrication regime due to better wettability (lower contact angle) and higher surface free energy. Increasing the Ne up to 50% in the discharge gas also leads to an increase of hardness of DLC films from 19 to 24 GPa.

Experimental Investigation of Lubrication Regimes of a Water-Lubricated Bearing in the Propulsion Train of a Marine Vessel

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Dov Avishai ◽  
Groper Morel
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Low Cost ◽  
Pollution Prevention ◽  
Elastohydrodynamic Lubrication ◽  
Sliding Bearings ◽  
Naval Vessel ◽  
Lubrication Regimes ◽  
Lubrication Regime

Abstract Sliding bearings, operating in a full hydrodynamic lubrication regime, exhibit a low friction coefficient and extended life. In recent years, with the increase in environmental awareness and pollution prevention, attention is being directed to oil spills, which pollute the environment. This is extremely prominent in ships and submarines whose propeller shafts are typically supported by oil-lubricated sliding bearings. To reduce pollution risk and also to obtain a simpler and low-cost maintenance system, the propeller shafts of numerous modern marine vessels are supported by water-lubricated bearings. An experimental investigation into the lubrication regime of a water-lubricated bearing in the propulsion train of a naval vessel is presented. A test rig was designed and built to allow testing of a scaled water-lubricated composite bearing supporting a naval vessel propeller shaft. Experimental results quantifying the effect of the rotational speed on the operating eccentricity, the friction coefficient, and the bearing’s lubrication regimes are presented. The experimentally obtained results are compared with an elastohydrodynamic lubrication (EHL) model solved by employing comsol multiphysics modeling software, and the differences are addressed. Finally, conclusions that may assist in better understanding the operation profile of the bearing and thus improving the vessel’s operability are presented.

The Lubrication Regimes of Mechanical Face Seals

2014 ◽  
Vol 630 ◽  
pp. 255-266
Author(s):  
Noël Brunetiere
Keyword(s):  
Friction And Wear ◽  
Hydrodynamic Lubrication ◽  
Rotation Velocity ◽  
Operating Conditions ◽  
Thermal Gradients ◽  
Lubrication Regimes ◽  
Seal Design ◽  
Lubrication Regime ◽  
Face Seals ◽  
Static Conditions

Mechanical face seals are usually described as contacting seals because their faces are in partial contact during static conditions. However, many experiments demonstrated that this contact is not maintained during operation. Indeed a full fluid film can separate the seal surfaces leading to lower friction and wear. In this paper, the mechanisms of lubrication taking place at the seal interface are reviewed and analyzed through simulations and experiments. It is shown that several lubrication regimes can be experienced, depending on the operating conditions and on the seal design. At low speed values the lubrication regime is mixed and turns to hydrodynamic lubrication regime when the speed is increased. At higher rotation velocity, the dissipated power generates thermal gradients and leads to thermally controlled lubrication regime. The transition between the lubrication regimes is also discussed and dimensionless parameters controlling the transition are proposed.

Transient Analysis of the Textured Journal Bearing Operating With the Piezoviscous and Shear-Thinning Fluids

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Di Zhang ◽  
Youbai Xie
Keyword(s):  
Transient Analysis ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Shear Thinning ◽  
Lubrication Regimes ◽  
Shear Thinning Fluids ◽  
Lubrication Regime ◽  
Start Up ◽  
Metal Metal ◽  
Bearing System

In this paper, a mixed lubrication model is presented to analyze the tribological behavior of the textured journal bearings operating from mixed to hydrodynamic lubrication regimes. In particular, the effects of fluid piezoviscosity and the non-Newtonian fluid behavior are also considered. The presented model solves the hydrodynamic lubrication problem by a mass-conserving formation of the Reynolds equation, whereas the metal–metal contact is considered by using the Greenwood and Tripp (GT) contact model which is linked with the hydrodynamic model based on the concept of Johnson's load sharing. As a result, the performance of the textured journal bearing system under different lubrication regimes, including boundary lubrication regime, mixed hydrodynamic lubrication regime, and hydrodynamic lubrication regime, can be evaluated. Using the journal bearing systems operated under the start-up condition as examples, prediction demonstrates the influences of texture distributions on friction and wear. It is found that the friction reducing effect induced by texturing is influenced by the distribution of the texturing zones. In particular, the hydrodynamic friction can be reduced when the eccentricity ratio is changed from high to low. Moreover, it appears that the shear-thinning effect of lubricant cannot be neglected in the transient analysis of journal bearing system.

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