Hydrodynamic bearing
To overcome defects in the supply of pressurized lubricant, a hydrodynamic bearing for guiding a shaft ( 14 ) includes a stationary outer annular wall, a rotatable inner annular wall ( 20 ), and a space ( 22 ) between the walls. The outer annular wall comprises an opening for supplying pressurized lubricant to the space so as to form a film of load-bearing fluid. The bearing includes a cavity ( 30 ) externally defined by the inner annular wall ( 20 ) and axially defined by two transverse annular walls ( 31 A, 31 B) secured to the shaft ( 14 ) and arranged on both sides of the cavity. The inner annular wall ( 20 ) comprises fluid connection orifices ( 32 ) connecting the cavity ( 30 ) to the space ( 22 ). The cavity ( 30 ) is divided into compartments ( 50, 52 ) by a partition wall ( 48 ) configured such that the cavity forms a lubricant supply for a transient operational phase.
1. Hydrodynamic bearing ( 16 ) intended to guide a shaft ( 14 ) in rotation about a longitudinal axis ( 17 ) defined relative to a support ( 12 ),
the hydrodynamic bearing comprising a stationary outer annular bearing wall ( 18 ) and a rotatable inner annular bearing wall ( 20 ) extending opposite the outer annular bearing wall ( 18 ) so as to provide an annular space ( 22 ) between the inner and outer annular bearing walls ( 18 , 20 ),
wherein the outer annular bearing wall ( 18 ) comprises at least one lubricant supply orifice ( 24 ) for supplying pressurised lubricant to said annular space ( 22 ) so as to form a load-bearing fluid film,
wherein the hydrodynamic bearing ( 16 ) comprises a cavity ( 30 ) externally defined by the inner annular bearing wall ( 20 ) and axially defined by two transverse annular walls ( 31 A, 31 B) secured to the inner annular bearing wall ( 20 ) and arranged on both sides of the cavity ( 30 ),
the inner annular bearing wall ( 20 ) comprising fluid connection means ( 32 ) that place the cavity ( 30 ) in fluid communication with said annular space ( 22 ),
wherein the hydrodynamic bearing ( 16 ) further comprises partitioning means ( 48 , 68 , 92 , 94 ) connected to the inner annular bearing wall ( 20 ) so as to divide the cavity ( 30 ) into a plurality of compartments ( 50 , 52 , 70 , 72 , 74 , 82 ), the partitioning means forming an obstacle to a flow of lubricant contained in at least one of the compartments under gravitational force (G), towards the fluid connection means ( 32 ), regardless of an angular position of the inner annular bearing wall ( 20 ) when the inner annular bearing wall is at a standstill, such that the cavity ( 30 ) forms a lubricant reserve for a transient operating phase.
2. Hydrodynamic bearing according to claim 1 , wherein the fluid connection means comprise a plurality of lubricant flow orifices ( 32 ) that pass through the inner annular bearing wall ( 20 ) and that are regularly distributed about the longitudinal axis ( 17 ).
3. Hydrodynamic bearing according to claim 1 , comprising a ring ( 40 ) intended to be mounted on the shaft ( 14 ) such that the ring can be removed therefrom, said ring ( 40 ) integrating said inner annular bearing wall ( 20 ) in addition to said two transverse annular walls ( 31 A, 31 B).
4. Hydrodynamic bearing according to claim 1 , wherein the partitioning means comprise a partition wall ( 48 ) of annular shape, dividing the cavity ( 30 ) into two compartments ( 50 , 52 ) arranged one behind the other along the longitudinal axis ( 17 ), said partition wall comprising at least one opening ( 54 ) defined by the inner annular bearing wall ( 20 ) and circumferentially offset relative to the fluid connection means ( 32 ).
5. Hydrodynamic bearing according to claim 1 , wherein the partitioning means comprise partition walls ( 68 ) extending longitudinally from one to the other of said transverse annular walls ( 31 A, 31 B), so as to divide the cavity ( 30 ) into a plurality of compartments ( 70 , 72 , 74 ) distributed about the longitudinal axis ( 17 ), the partition walls ( 68 ) being circumferentially offset relative to the fluid connection means ( 32 ).
6. Hydrodynamic bearing according to claim 1 , wherein the partitioning means divide the cavity ( 30 ) into a plurality of compartments ( 82 ) circumferentially offset relative to the fluid connection means ( 32 ) and regularly distributed about the longitudinal axis ( 17 ), and into a distribution channel ( 84 ) connecting each compartment ( 82 ) to the fluid connection means ( 32 ) and comprising a circumferential portion ( 86 ) that is axially offset on a same side relative to each compartment ( 82 ) and the fluid connection means ( 32 ), in addition to first connection portions ( 88 ) that respectively connect the compartments ( 82 ) of the cavity to the circumferential portion ( 86 ) of the distribution channel and which are angularly offset relative to circumferential ends ( 90 ) of each compartment.
7. Hydrodynamic bearing according to claim 6 , wherein the fluid connection means ( 32 ) are located axially on a same side of the circumferential portion ( 86 ) of the distribution channel ( 84 ) as the compartments ( 82 ) of the cavity ( 30 ).
8. Turbomachine ( 100 ), in particular for an aircraft, comprising a support ( 12 ), a shaft ( 14 ) and at least one hydrodynamic bearing ( 16 ) according to claim 1 , the outer annular bearing wall ( 18 ) of which is secured to the support ( 12 ) and the inner annular bearing wall ( 20 ) of which is secured to the shaft ( 14 ), such that the hydrodynamic bearing ( 16 ) contributes to the guiding of the shaft ( 14 ) in rotation.
9. Turbomachine according to claim 8 , wherein the shaft ( 14 ) forms a part of an accessory gear box ( 108 ) of the turbomachine.
10. Method for lubricating a hydrodynamic bearing ( 16 ) according claim 1 , comprising:
at least one transient operating phase wherein lubricant ( 60 ) previously stored in the cavity ( 30 ) is injected into said annular space ( 22 ) by passing through the fluid connection means ( 32 ) under centrifugal force, and
a steady-state operating phase, wherein pressurised lubricant is supplied to said annular space ( 22 ) through each lubricant supply orifice ( 24 ), and a part of the lubricant penetrates the cavity ( 30 ) through the fluid connection means ( 32 ).