Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/02—Parts of sliding-contact bearings
  • F16C33/04—Brasses; Bushes; Linings
  • F16C33/06—Sliding surface mainly made of metal
  • F16C33/10—Construction relative to lubrication
  • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
  • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
  • F16C33/1075—Wedges, e.g. ramps or lobes, for generating pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C17/00—Sliding-contact bearings for exclusively rotary movement
  • F16C17/02—Sliding-contact bearings for exclusively rotary movement for radial load only
  • F16C17/028—Sliding-contact bearings for exclusively rotary movement for radial load only with fixed wedges to generate hydrodynamic pressure, e.g. multi-lobe bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C32/00—Bearings not otherwise provided for
  • F16C32/06—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings
  • F16C32/0629—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings supported by a liquid cushion, e.g. oil cushion
  • F16C32/064—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings supported by a liquid cushion, e.g. oil cushion the liquid being supplied under pressure
  • F16C32/0651—Details of the bearing area per se
  • F16C32/0659—Details of the bearing area per se of pockets or grooves

Definitions

• Hydrodynamic pad with asymmetrical lobes Hydrodynamic pad with asymmetrical lobes.
• the present invention relates to a four-lobe hydrodynamic bearing intended to operate at high loads and at high speeds while having a stable operation when empty. Its specific capabilities are particularly sought after in the case of gear shafts of gearboxes or gear multipliers with high power gears.
• the angular apertures of the lobes are identical, and four oil feed grooves are machined between the lobes.
• Such a configuration, in which the centers of the lobe bores are eccentric with respect to the geometric center of the pad, makes it possible to obtain four precharge effects on the shaft. These effects are particularly advantageous for improving the hydrodynamic stability of the shaft-carrying film in the case of low radial load and high speed operation, or in the case of operation of rapid tree lines with critical dynamic behaviors.
• the symmetrical arrangement of the lobes further allows the shaft to rotate in both directions of rotation with identical lift. Assuming the choice of important values of lobe eccentricity to produce high precharges, it is also possible to guarantee that, whatever the angular direction of the load, the shaft will never come into position on a groove. oil distribution, which would have the effect of causing a fall in lift of the shaft or hydrodynamic vibration instabilities.
• the use of a symmetrical lobe pad is therefore particularly well suited to high speed operation cases. sliding and for variable radial loads of low or moderate level, angular orientation also variable.
• the angular aperture of each of the feed grooves is of the order of 20 °, which limits the angular aperture of each of the bearing surfaces at about 70 °.
• This value explains the low load capacity of a standard four-lobed pad in comparison with, for example, that of a pad with two fixed lobes whose active openings are greater than 150 °.
• the object of the present invention is, by modifying the angular apertures of each of the four lobes, to allow high load capacities to be obtained, while maintaining the aforementioned advantages of the symmetrical four-lobed pad.
• the hydrodynamic pad of the invention also provided with four lobes with centers of curvature eccentric with respect to its geometric center, said lobes being conventionally separated by oil supply grooves, is mainly characterized in that that the lobes are asymmetrical and present:
• the four lobes do not perform the same functions, hence their different geometry. It is thus possible to assign to one of the lobes a much larger angular aperture than that of the others, so as to obtain a maximum lift surface.
• this lobe is the charge lobe.
• the high value of its angular aperture makes it possible, with the same applied force, to obtain lower pressure point values in the oil wedge and higher oil film thicknesses.
• This improved bearing performance results in an improvement in endurance resistance of the anti-corrosion metal. friction of the sliding surface and a reduction of the temperature where the thickness of the film is minimal.
• the eccentricity, relative to the geometric center of the bearing, the center of the maximum angular aperture lobe and the value of the load angle are chosen so as to have the optimum conditions of lift of the oil film.
• the other three lobes, of smaller angular aperture, are lobes of maintenance and stabilization. For this reason, the offsets of their center have values much higher than the eccentricity of the center of the load lobe.
• the choice of offsets and angular apertures of the active surfaces of the four lobes ensures continuity of guiding of the shaft. As in the case of a symmetrical four-lobe bushing, the shaft can not come into contact with the lubricating and cooling devices arranged between the end of the active sliding surface of a lobe and the beginning of the active zone. of the next lobe.
• the lobes may also have at least two different axial widths.
• the minimum clearance points of two opposing lobes are aligned with the geometric center of the bearing.
• these points are located on a circle whose diameter corresponds to the assembly diameter of the pad.
• each of these half-shells may comprise two lobes and two grooves.
• the joint plane of the bushing is angularly oriented so that the nominal load is directed on the load lobe.
• FIG. 1 is a sectional view of a bearing with symmetrical four lobes constituting the prior art
• FIG. 2 represents a pad with four asymmetrical lobes, which is the subject of the present invention.
• the four lobes (1, 2, 3, 4) are symmetrical, that is to say that they have the same angular aperture and the same radius of curvature.
• the four centers (01, 02, 03, 04) of the arcs that constitute them are arranged symmetrically with respect to the geometric center (O) of the pad, which is in practice located at the intersection of the diagonals of the square constituted by said points. (01 to 04).
• the lobes (1, 2, 3, 4) are separated by grooves (5, 6, 7, 8) provided for the oil supply.
• the circle (9) represented in FIG. 1 in dashed lines passes through the four points which appear at the place where the arrows schematizing the four lobes (1, 2, 3, 4) point at the intersection between said lobes.
• such a pad is adapted to operating hypotheses with high sliding speed and variable radial loads of low to moderate level.
• This pad is asymmetrical, that is to say that the angular sectors covered by each of the lobes (L1, L2, L3, L4) are different.
• the eccentricities of the centers (01, 02, 03, 04) with respect to the geometric center (O) of the bearing are also variable from one lobe to the other.
• the lobe (L1) is the lobe of charge. Its angular aperture is therefore much higher than that of the lobe (L2), so as to obtain a maximum lift surface.
• the pad is in this case constituted by two half shells (10, 11).
• the lobes (L1) and (L2) are located in the half-pad (10), while the lobes (L3) and (L4) are arranged in the other half-pad (11).
• the joint plane is oriented angularly so that the nominal load is directed on the lobe (L1).
• the angular sector of the lobe (L1), as well as the radius of curvature and consequently the eccentricity of (01) with respect to (O) allows optimum lift of the oil film resulting in particular from a decrease in peak values.
• the anti-friction metal of the sliding surface has a better mechanical endurance due to these increased lift performance.
• the lobes (L2) to (L4) are stabilization and holding lobes with greater eccentricities of the points (02) to (04) than that of the lobe (L1).

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Sliding-Contact Bearings (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (4)

Cited By (1)

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• 2007
  • 2007-05-24 FR FR0703691A patent/FR2916498B1/fr not_active Expired - Fee Related
• 2008
  • 2008-05-23 WO PCT/FR2008/050897 patent/WO2008149038A2/fr not_active Ceased
  • 2008-05-23 US US12/451,532 patent/US20100092115A1/en not_active Abandoned
  • 2008-05-23 EP EP08805841A patent/EP2147222A2/de not_active Withdrawn

Non-Patent Citations (1)

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