10 Sep 2019 15:50
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Bearings Plus offers a complete line of hydrodynamic fluid film bearings for rotating machinery. To enable a better understanding of the conditions within the bearing the actual load of the oil may be thought of as being divided into an inner load P and an outer load P The inner load, prior to the actual work loaded operation of the spindle is caused by the force required to deform the shell 3 and pre-stress spring 7 when the oil film 6,, is created and further by the static pre-stressing P, Thus, when the spindle 2 is placed into initial rotation the inner force P directly equals the hydrodynamic force P and the spindle assumes a balanced position concentric about the center 0.
Still further, the stiffness and damping coefficients of the dampers 71 can be selectively varied and controlled by changing the metal mesh material, geometry and mesh density depending upon the operating conditions encountered in the bearing chamber 56 tiliting pad during rotation of the shaft 55. The metal mesh dampers 71 also provide maximum damping at lower frequency ranges, wherein rotordynamic instability frequencies are significantly lower than the rotor synchronous frequency or shaft rotational frequency.
New advances in bearing design have contribute: Tilting Pad with Embedded Pocket Bearing, Flexible Pivot Bearings, Hydraulic Lift Bearings, and Hybrid Bearings Each of these bearing designs offers a unique mechanical arrangement that provides a specific advantage.
For example, combining directed lubrication with advanced material bearings — which are capable of handling thinner films, higher temperatures and therefore higher loads — can greatly reduce power loss compared to a flooded design with traditional bearing materials such as babbitt.
Prismatic member 5 is pushed against the pre-stressing spring 7. The amount of this push, in the vertical direction is three times the thickness of the oil film (i.e.: 3 8 Consequently, the direct vertical movement of the spindle 2 is twice the thickness of the film of oil (i.e.: 2 8 as seen in FIG.
The non-rotating journal bearing 2 has a pair of annular flanges 8 that support the journal bearing and attach to the bearing spring support 20. These flanges have a circular array of bolt holes 10 that align with a corresponding array of bolt holes 22 in the spring support.
Three equidistant points from the wall of the housing bore 1a. The first point'of support isalong the central vertical axis of the housing bore 1a where the housing body 1, itself, is bored to provide a vertical hole 16 directed radially toward the center of the bore 1a. A compression spring 7, of preselected spring rate, is set within the hole 16 and bears at its lower end against a rest or stop member 6. The stop rest member 6 is generally in block form and has a cylindrical recess 17 formed in its lower surface, which recess 17 is adapted to receive a cylindrical prismatic body 5. The prismatic body has a lower surface which is conformingly shaped to that of the outer surface of the shell 3, and is provided 'with a central axial slot which causes the member 5 to press against the shell along two axial lines to either side of the slot.
13. A bearing as in claim 10 further comprising a squeeze film damper comprising a squeeze film cylinder within said spring support between said spring bars and said cylindrical surface, a fluid squeeze film between said squeeze film surface and said spring support and one or more fluid plenums adjacent said squeeze film cylinder, said spring support moved by the flexure of said spring bars, movement of said spring support against said squeeze film dampens vibration.
2. A bearing as in claim 1 wherein said spring support is sectioned into at least two opposing sections each having a plurality of said spring bars, the spring bars of said opposing sections being interleaved and supported by said stationary ring assembly.
The opposite ends of the bearing 52 include annular bearing flanges 66 which define outer bearing surfaces 67 and 68 which face toward the chamber surface 58. The outer bearing surfaces 67 and 68 are spaced inwardly from the chamber surface 58 a small radial extent to define radial spaces 69 and 70. As will be described further herein, each of the radial spaces 69 and 70 is provided with a compliant structural damper 54.
The eccentric positioning of the shaft with respect to the foil and the continuous rotation of the shaft causes the establishment and maintenance of high and low pressure regions in the clearance, flow of fluid from the high pressure region to the low pressure region resulting in establishment of a fluid film which supports the journal, preventing contact between the journal and the foil.
The parameters used in the analysis of journal bearing are: eccentricity ratio (ε) = 0.5; couple stress parameter (λ) = 0.1, 0.2, 0.3, 0.4; dynamic viscosity ratio of surface layer to couple stress fluid film (α) = 10, 100 and non-dimensional surface layer thickness (Δ) = 0.025, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4. The influence of couple stress parameter and high viscosity surface layer on the load capacity enhancement and coefficient of friction reduction for journal bearing are analyzed.