Dynamically Loaded Journal Bearings: Maximum Film Pressure

1969 ◽  
Vol 91 (3) ◽  
pp. 534-537 ◽  
Author(s):  
J. F. Booker
Keyword(s):  
Film Thickness ◽  
Orbit Determination ◽  
Journal Bearings ◽  
Film Pressure ◽  
Dynamically Loaded

Most analyses of dynamically loaded journal bearings produce only film-thickness information directly; this paper provides a conceptually simple means for calculation of film-pressure information subsequent to (or concurrent with) journal orbit calculations. Though the proposed methods for pressure determination complement previous “mobility” methods for orbit determination (since both involve an observation frame rotating with the load), they are in fact quite independent.

Wall Slip in EHD Journal Bearings

2008 ◽  
Author(s):  
A. Fatu ◽  
M. Hajjam ◽  
D. Bonneau
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Power Loss ◽  
Wall Slip ◽  
Journal Bearings ◽  
Ehd Lubrication ◽  
Lubrication Performance ◽  
Dynamically Loaded

In the present paper the influence of wall slip on the EHD lubrication performance is studed. Steady state and dynamically loaded bearings are investigated. The results show that well-chosen slip/no-slip regions can increase the film thickness and considerably decrease the power loss.

Linking Rigid and Flexible Multibody Systems via Thin Fluid Films Actively Controlled

2008 ◽  
Author(s):  
Edgar A. Estupinan ◽  
Ilmar F. Santos
Keyword(s):  
Film Thickness ◽  
Multibody Systems ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Fluid Film ◽  
Fluid Films ◽  
Thin Fluid ◽  
Dynamically Loaded ◽  
Reaction Forces ◽  
Fluid Film Thickness

This work describes in details the steps involved within the mathematical modelling of multibody systems (rigid and flexible) interconnected via controllable thin fluid films. The dynamics of the mechanical components are described with help of multibody dynamics and finite element method. In this paper, the methodology is applied to reciprocating machines such as hermetic reciprocating compressors and internal combustion engines. In previous studies [1], it has been shown that for a light duty vehicle, the friction losses may reach until 48% of the total energy consumption of an engine and from that, almost 30% are coming from bearings and crankshaft. Therefore, considering that the dynamics of the fluid films in the journal bearings can be actively controlled by means of different types of actuators, allowing significant reduction of wear and vibrations, one of the aims of this paper is to study the feasibility of applying active lubrication to the main journal bearings of reciprocating machines. In this framework the paper gives a theoretical contribution to the combined fields of fluid-structure interaction and active vibration control. The hydrodynamic pressure distribution for an active lubricated finite journal bearing dynamically loaded can be calculated by numerically solving the modified Reynold’s equation [2], by means of finite-difference method and integrated over the pressure area in order to obtain the dynamic reaction forces among components. These forces are strongly nonlinear and dependent on the relative kinematics of the system. From the point of view of active lubrication and specifically considered the case of a dynamically loaded journal bearing, the injection pressure should be controlled in the time domain. However, taking into account that the pressures and reaction forces in a reciprocating machine have a cyclic behaviour, the fluid film thickness of the main bearings may be modified by controlling the oil pressure injection, depending on the crank angle and the load bearing condition. It can be mentioned that the pressure and flow may be controlled by mechanical cam systems, piezoelectric nozzles [3] [4] or servovalves [5] [6], therefore, an adequate control strategy has to be defined. The fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the mechanical system. Such a set of equations is numerically solved giving some insights into the following parameters: a) maximum fluid film pressure, b) minimum fluid film thickness, c) maximum vibration levels and d) viscous frictional forces. The behaviour of such parameters is investigated when the system operate with conventional hydro-dynamic lubrication, passive hybrid lubrication and controlled hybrid lubrication.

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