Patent Grant
10677286
This application is a continuation, under 35 U.S.C. § 120, of copending international application No. PCT/EP2017/060987, filed May 9, 2017, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of European patent application No. EP 16 290 090, filed May 26, 2016; the prior applications are herewith incorporated by reference in their entireties.
The present invention relates to a hydrodynamic bearing that is designed to bear a rotor or rotary shaft according to the preamble of the independent claim.
The present invention relates in particular to hydrodynamic bearings that are able to bear a rotor or rotary shaft and to guide same in rotation, such as the bearings commonly used to bear high-speed/high-power rotary shafts (reduction gear or step-up gear) for the gas and oil energy market. The bearings according to the invention are particularly suited to use with high radial loads and high shaft speeds.
Such a bearing is for example described in patent application US 2002/0018604 A1. Such a bearing is typically formed by a body with an inner surface forming a circular cavity arranged to receive a rotary shaft, for example the rotary shaft of a pinion of a reduction gear, such as to bear said shaft and guide same in rotation. Said inner surface forming said circular cavity can for example act as a sliding surface for said rotary shaft. In other variants, said body of said bearing can for example include pads distributed about the inner surface of said body, said pads having a substantially arched surface that is oriented toward the center of the cavity and acts as a sliding surface for said rotary shaft. Normally, a lubricant supply device enables the lubrication of the interstices separating the outer surface of the rotary shaft from said sliding surface and the formation of a lubricant film between the outer surface of said shaft and each sliding surface when said shaft is in rotation at a rotational speed greater than a limit speed defined by the dimensioning of the bearing and of the shaft, said lubricant (for example the viscosity thereof), geometry and the forces involved in the bearing/shaft system. The basic principle of the hydrodynamic bearing is to have said lubricating film interposed between the shaft and the sliding surface, said film enabling said shaft to rotate without contact with said sliding surface from said limit speed.
Unfortunately, the hydrodynamic bearings known by the person skilled in the art that are suitable for high loads and high speeds, such as the bearing described above, suffer from the following problems:
One purpose of the present invention is to propose a new type of hydrodynamic bearing that helps to reduce power losses caused by friction, lubricant consumption, instabilities and said lubricant flow, notably an axial lubricant flow, and to reduce losses caused by spray from gears.
For this purpose, a hydrodynamic bearing is described by the characteristics of the independent claim.
A set of subclaims also sets out advantageous embodiments of said bearing according to the invention.
The present invention therefore notably relates to a hydrodynamic bearing including a body extending in particular axially along a longitudinal axis A, said body having an inner surface forming a cavity or opening that is for example cylindrical and that also extends in particular axially along said axis A and radially about said axis, said cavity being notably open at each of the axial ends thereof and being designed to receive and surround a rotary shaft, which is usually cylindrical, extending axially along said axis A. In particular, said axis A is an axis of revolution of said cavity. According to the present invention, a plurality of pads are mounted, preferably in an oscillating manner in relation to the inner surface of said body, and installed in said cavity, for example on said inner surface of said body, such as to support said rotary shaft and to guide same in rotation about the longitudinal axis of rotation thereof in a direction of rotation w from “upstream” to “downstream”. The pads of the bearing according to the invention may for example be curved pads (i.e. in the form of a sector of a hollow cylinder) extending over a portion of the circumference of the inner surface, with the width thereof extending axially along said axis A. Each pad in particular has an upper face oriented toward the center of the cavity, i.e. oriented toward said rotary shaft, and including an active surface designed to act as a sliding surface for said rotary shaft. Said active surface according to the invention is the surface of the pad that is liable to come into contact with said rotary shaft, for example when this latter is bearing against said pad. As opposed to the upper face, the pad has a lower face oriented toward the inner surface of said body and resting for example at least partially against said inner surface. Preferably, each pad, or more precisely the upper face of each pad, can thus be defined as having an active surface and an inactive surface, the active surface including all of the surfaces of the upper face of the pad that are at a minimum radial distance M from the longitudinal axis of rotation of said rotary shaft, as opposed to the “inactive” surface, which includes all of the surfaces of the pad that are at a radial distance M′ greater than M and that therefore cannot come into contact with said rotary shaft when this latter bears against said pad, for example when this latter is no longer in rotation. Preferably, said body is ring shaped, the cavity then simply being a cylindrical opening at the center of the ring, i.e. of the annular body, said ring including said pads installed on the inner periphery thereof that forms said inner surface, the diameter of the cavity then being for example equal to 2M.
The bearing according to the invention includes in particular:
Preferably, the active surface of each of said pads of the active angular sector has a smooth surface in the form of a central strip in relation to the width of said pad, said smooth surface thus extending, in the direction of rotation w, i.e. about the circumference of said cavity, unbroken from one end to the other end of said pad, and, across the width of said pad, i.e. along the axis A, over a central portion of said pad, preferably only over a central portion of said pad. The upper face of the pad according to this embodiment thus includes, for example, an inactive surface formed by two lateral strips of smooth surfaces extending unbroken from one end to the other of said pad and laterally edging said central active-surface strip of said pad.
Preferably, the active surface of at least one pad of the passive angular sector has a sculpted surface designed for example to create secondary grooves oriented toward said lateral groove such as to guide said lubricant toward the latter when the rotary shaft is in rotation. According to this embodiment, said secondary grooves are formed from the active surface into the thickness of said pad, the “bottom” of said secondary grooves then belonging to the inactive surface of said pad and enabling said lubricant to be collected and guided toward said lateral grooves. In particular, said active surface of said pad of the passive angular sector has a smooth surface in the form of a central strip, as described above, and two sculpted-surface lateral strips arranged on either side of the smooth surface along said width of said pad, i.e. respectively on one lateral side of the strip-shaped smooth surface and on the other lateral side of said strip-shaped smooth surface, each of said sculpted-surface lateral strips having said secondary grooves used to guide a flow of lubricant from said central-strip-shaped smooth surface toward said lateral lubricant-drainage grooves. Preferably, at least one or each secondary groove forms an oblique angle with a plane perpendicular to said axis A. In particular, said secondary grooves are the arms of a chevron or a “V”, the point of which is in the central portion of the pad or belongs to said central-strip-shaped smooth surface.
According to a preferred embodiment, the bearing according to the invention in particular includes an annular lateral ring arranged laterally against the body of said bearing and designed to prevent an axial flow (i.e. oriented along the axis A) of said lubricant out of said cavity, said lateral ring being preferably attached to said bearing body such as to create said lateral groove. In particular, the lateral groove or said lateral ring has at least one calibration orifice to control a rate of lubricant leakage from said bearing, said calibration orifice in particular including a leakage rate adjustment system, for example using a screw system. Said bearing according to the invention in particular includes a first lateral groove and a second lateral groove that are arranged laterally on either side of said bearing, each one preferably being formed by attachment of a lateral ring to the body of said bearing. Said first and second lateral grooves are notably designed to prevent an axial flow of lubricant out of the bearing, each lateral groove being able to collect an axial flow from said active surface of the pads of said bearing and to guide same such that said flow is drained radially to the outside of said bearing, notably via said calibration orifice. Each of the lateral grooves cooperates notably with the deflectors to drain the lubricant laterally.
According to the present invention, at least two consecutive pads are preferably coupled to one another by an elastic system that is designed to limit any angular floating of said pads. For example, the end of one of said pads is coupled by said elastic system to the closest end of at least one of the neighboring pads thereof, said elastic system including for example an open elastic ring, each end of which is coupled to a respective pad. Preferably, each pad is coupled to each of its closest neighboring pads by said elastic system.
Preferably, the deflector according to the invention has a first portion and a second portion, each extending for example axially along said axis A over at least some and preferably all of the width of said bearing, the first portion being designed to be arranged upstream of the second portion in relation to the direction of rotation w and beneath the level of the active surface of the closest pad or pads when said deflector is fitted to said bearing, said first portion being designed to recover and drain said lubricant laterally, the second portion extending radially toward the center of the cavity notably up to a radial distance separating same from the center of the cavity equal to the radial distance separating said closest active surface or surfaces from said center of the cavity, for example extending at most as far as said radial distance M, such as to at least partially prevent a movement of said lubricant from a zone upstream of said second portion to a zone downstream of said second portion, said second portion also preferably extending upstream above the first portion (i.e. such as to overhang said first portion or in other words to form a projection radially to the vertical of said first portion in a centripetal direction). In particular, the second portion includes a flat upper surface inscribed or contained in a plane, the extension of which is tangent to at least one active surface of one of the closest pads, said flat upper surface extending in an upstream direction to overhang at least a portion of said first portion. According to the present invention, “beneath the level of the active surface” means that the first portion is further away from the center of the cavity than the active surface. Indeed, according to the present invention, the concepts “above” and “beneath” are defined in relation to the center of the cavity, and thus an object O1 is above and respectively beneath an object O2 if the object O1 is placed in a radial position nearer to, or respectively further away from, the center of the cavity in relation to the position of the object O2. Furthermore, the distance in relation to the center of the cavity is preferably and generally the radial distance separating a point or an object from said axis A, said axis A being in particular an axis of revolution of the cavity notably if the latter is cylindrical.
In particular, each injector and/or each deflector is attached removably to said body of said bearing, for example in a space between two successive pads, and said space can be formed in or hollowed out from the body of said bearing, at least in part, and opens out notably toward said cavity. Preferably, each space designed to receive an injector and/or a deflector is oblong in shape, the length of said space being oriented axially, i.e. along the width of said bearing, extending for example over the entire width of said bearing. Each space in particular has at least one radial opening that is for example hollowed out of the body of said bearing, that is oriented toward the outside of said bearing and that is formed for example by one or more channels oriented substantially radially toward the outside of said bearing, in order to enable lubricant to be supplied to said injector, notably radially from the outside of said bearing, or the lubricant recovered by the deflector to be drained, said lubricant being then drained radially toward the outside of said bearing, for example at the axial ends of said space.
Preferably, the deflector has an oblong body designed to be inserted into said space, said oblong body being formed by said first portion and said second portion, which are both also oblong shaped. An axial section of said first portion, i.e. along the length thereof, and in a plane passing through said axis A and extending radially to intersect said deflector along the length thereof when the latter is installed in one of said spaces, in particular forms a triangular shape or is preferably triangular, for example an isosceles triangle, the triangular shape having in particular an axis of symmetry splitting the width of the pads, or the length of said first portion, into two equal portions, and an apex pointing toward said axis A. In particular, said apex is an apex common to the two sides of equal length of said isosceles triangle and points toward said axis A when said deflector is inserted into said space and is positioned in the median plane of the pad, i.e. the plane splitting said pad along the width thereof into two portions of equal width. In particular, said apex belonging to said first portion is thus located beneath the level of the active surface of the closest pad or pads when said deflector is installed in said space to recover said lubricant and to guide same laterally along slopes joining at said apex and forming the sides of the triangular shape, said lubricant being guided along said slopes such as to move away from the center of the cavity or of the rotary shaft as far as the lateral drainage grooves. Said slopes are for example the sides of equal length of said isosceles triangle. Preferably, said section forming said triangular shape is constant along the width of the first portion of said deflector.
According to a preferred embodiment, said section forming a triangular shape is kept constant from upstream to downstream along the entire width of said first portion, said deflector then forming, directly downstream of said first portion forming the constant triangular section, said second portion of said deflector, which for example has a rectangular axial section, said second portion thus being potentially parallelepipedic, said second portion forming in particular a side or face oriented toward the center of the cavity and for which the radial distance separating said side from said center of the cavity or from the axis A is equal to the radial distance separating the active surface of the closest pad or pads from the center of the cavity or the axis A. Optionally, said side includes an extension oriented upstream, partially covering the first portion of said deflector characterized by said section forming a triangular shape, without however touching this latter, i.e. in a contactless manner in relation to this latter, such as to form said overhang above said section forming the triangular shape of said first portion. In particular, said extension extends upstream over the entire length of the first portion of said deflector. Advantageously, this section forming the triangular shape of said first portion, optionally in cooperation with said portion of rectangular section that can form said extension at least partially overhanging the section forming the triangular shape, enables the efficient recovery and lateral drainage of the lubricant during rotation of the rotary shaft, notably symmetrically along each of the sides of the triangular shape of the first portion of said deflector.
The injector according to the invention is either a device separate from said deflector, i.e. the injector and the deflector are two distinct devices, or is built into said second portion of said deflector, the first and second portions of said deflector thus forming an “injection/deflection” device, i.e. the deflector also performs the injection function on account of the features of the second portion thereof, as shown below in
Said injector, for example the second portion of said deflector in the case of a deflector incorporating the injection function, preferably comprises an oblong body designed to be mounted in one of said spaces, for example between two successive pads. Said oblong body is preferably substantially parallelepipedic, and is oriented lengthwise along said axis A. Said oblong body in particular includes an axial channel arranged axially along same, i.e. along the length thereof, that is closed or closable using partitioning means for each of the axial ends thereof, i.e. in the direction of said lateral drainage grooves when said injector is installed in said space, said axial channel being designed to supply lubricant to said active surface of the closest downstream pad and forming part of a lubricant feed circuit. Preferably, the position of said partitioning means can be adjusted between a closed position and an open position such as to enable the blocking of the axial ends of said axial channel to be varied, such that a flow of lubricant is prevented from leaving said axial channel via the axial ends thereof when in the closed position, and a flow of lubricant can leave said axial channel via the axial ends thereof in the direction of said lateral grooves when in an intermediate position between the open position and the closed position. The adjustment of the partitioning means advantageously makes it possible to adjust the flow rate of lubricant leaving via the axial ends of said axial channel. Said axial channel is in particular provided with a connection member enabling connection to a lubricant supply channel, said connection being possible notably via said radial opening of said space designed to receive the injector or the injection/deflection device.
Said axial channel of said injector in particular has one or more output orifices oriented toward the cavity of said bearing, for example in the direction of the axis A, in order to supply lubricant to said active surface of the pads. In particular, each output orifice is oriented, for example radially, toward a lubrication surface of said injector, which is at a radial distance from the center of the cavity or from the axis A that is substantially equal to the radial distance separating the active surface of the closest pad from the center of the cavity or the axis A, said orifices opening out onto said lubrication surface. Said lubrication surface may for example include a conduit extending for example over the entire length of said injector and onto which each of said orifices opens out. Said conduit notably enables a uniform distribution of said lubricant over the entire width of the active surface of the pad. Said orifices are notably also spaced apart from one another on said lubrication surface and in the axial direction, i.e. the length of the body of said injector. Preferably, at least some of said orifices have a diameter that is different from at least one other of said orifices such as to maintain an identical flow rate for all of the orifices of said injector. Indeed, according to the present invention, said diameter of said orifices is determined by calculating the pressure drop upstream of each orifice in the lubricant feed circuit such as to maintain said identical flow rate for each orifice, regardless of the axial position thereof along the length of said injector. Accordingly, varying the diameter of the orifices makes it possible to compensate for pressure variations in the lubricant during distribution thereof via said orifices by means of said lubricant feed circuit, such that each orifice distributes the same quantity of lubricant as a function of time.
According to a preferred embodiment of the present invention, the second portion of said deflector includes said injector in order to form said injection/deflection device. This latter is therefore made up of two portions, respectively an injection portion and a deflection portion, said injection portion being said second portion of the deflector described above incorporating said injector, and the deflection portion being formed by said first portion as described above, each injection/deflection device being designed to be installed in one of said spaces such that the deflection portion is positioned upstream of said injection portion, said injection/deflection device thus combining the injector function and the deflector function in a single removable device. Indeed, according to this preferred embodiment, said deflector and said injector form a single removable device referred to as an injection/deflection device, which can be installed in a space in said bearing, for example between two consecutive pads.
According to the present invention, the angular distance separating one injector from another injector positioned directly upstream or downstream is preferably π/n [rad], where n is the total number of injectors in said bearing, respectively the angular distance separating one deflector from another deflector positioned directly upstream or downstream is preferably π/m [rad], where m is the total number of deflectors in said bearing. In particular, m and n are equal to or greater than 2. Preferably, m=n=5. In particular, according to the preferred embodiment including said injection/deflection devices, the angular distance separating one injection/deflection device installed in a space in said bearing from a neighboring injection/deflection device installed directly upstream or downstream in the next space of said bearing is π/t [rad], where t is the total number of injection/deflection devices mounted in the spaces in said bearing. Preferably, t is equal to or greater than 3, in particular t=5.
Advantageously, said deflectors help to stabilize the shaft during rotation thereof at high speed by guiding the lubricant toward said lateral grooves, thereby reducing or eliminating an axial flow of lubricant out of said bearing, said lubricant being forced to follow a path defined by the geometric shape of said deflector that guides said lubricant toward either the first or the second lateral groove. Thus, according to the present invention, the axial flow out of the bushing of said bearing is prevented by capturing the lubricant no longer used to form the hydrodynamic film using said deflectors and guiding this latter from the deflector to one of the lateral grooves.
In particular, said lateral grooves according to the invention extend about the circumference of said cavity such as to edge each of the lateral sides of the pads of said bearing in order to collect an axial flow of lubricant. According to a first embodiment, each lateral groove can be a groove in the form of an arc of circle hollowed out of or formed in the body of said bearing such as to open out toward said cavity, and for example extending along one of the lateral edges of said body of said bearing. Each lateral groove can for example extend along at least one portion of the internal circumference of said bearing, extending for example over 180° or over all of the passive angular sectors, or preferably over the entire internal circumference of said bearing, i.e. over the entire circumference of the cavity. According to a second embodiment, each of said lateral grooves is obtained by attaching said annular lateral ring to each of the lateral sides of said bearing, said annular lateral ring having a minimum internal diameter that is substantially equal to twice the radius separating the active surface of a pad from the center of the cavity (or the axis A), the portion of the ring oriented toward said body and designed to be attached to a lateral face (i.e. along the axis A) of this latter is characterized by a structural geometry designed to form one of said lateral grooves when said ring is attached laterally to the body of said bearing. For example, said portion of the ring that is oriented toward said body is characterized by an internal diameter that is greater than said minimum internal diameter such as to create a cavity (i.e. said lateral groove) between said lateral face of said body and the portion of the ring characterized by said minimum internal diameter. In this case, said ring can be described as being formed by two rings that are rigidly connected to one another, respectively a first ring characterized by said larger internal diameter and a second ring characterized by said minimum internal diameter, said ring being designed to be mounted on a lateral side of said bearing (i.e. on one of said axial ends of said bearing) with the portion thereof formed by said first ring coming into contact with said lateral side.
Preferably, each of said lateral grooves has at least one radial opening, for example a radial bore, that is designed to be arranged to face the longitudinal end of the first portion of said deflector, and that is designed to drain the lubricant collected in the lateral groove radially to the outside of said bearing, for example toward a circulation or recirculation system for said lubricant.
Advantages of said bearing according to the invention and exemplary embodiments and applications are provided using the following figures, in which identical reference characters indicate identical or equivalent elements:
The cavity of said body 1, or in other words the hollow portion of said bearing, is arranged to receive said rotary shaft in order to guide and support same when in rotation in a direction of rotation w from “upstream” to “downstream” about said axis A. In particular, a plurality of radial holding pads 2 for said rotary shaft are mounted, for example in an oscillating manner, on the inner surface of said body 1 forming said cavity, such as to support said rotary shaft and to guide same in rotation. For this purpose, each pad 2 has an upper face 11 with an active surface acting as a sliding surface for said rotary shaft when same is rotating in the direction of rotation w. As shown in
Considering for example a bearing split into n zones zi (i being a value from 1 to n) including at least said zone in which the force exerted on said bearing by the rotary shaft in rotation is greatest and said zone in which the force exerted on said bearing by the rotary shaft in rotation is least, i.e. n≥2, the rotary shaft exerting a force Fi on the zone zi, an active angular sector is in particular defined as being all of the zones in the n zones zi of said bearing for which the force Fi exerted by the rotary shaft in rotation is greater than X times the average of the forces exerted by said rotary shaft in rotation on each of said zones, X in particular being a value between 1 and 1.5, and preferably X=1.5. In other words, if
where X∈[1,1.5] then the zone zi on which the force Fi is exerted belongs to the active angular sector. Preferably, a pad at least partially within the active angular sector is considered to be fully part of said active angular sector.
According to the preferred embodiment shown in
According to the present invention, each pad 2 within a passive angular sector 2B is characterized by an active surface that is lower than the active surface of a pad 2 within an active angular sector 2A. According to the present invention, the active surface of a pad includes all of the points of the upper face 11 of said pad that come into contact with said rotary shaft when the latter turns from upstream to downstream on said upper face 11. This is usually all of the points located at a radial distance M from the axis A, the radial distance M being the shortest distance separating the upper face 11 of said pad from the axis A. As shown for example in
As shown in
According to the preferred embodiment shown in
The lateral grooves 15 according to the present invention can be made in various different ways. According to a first embodiment (not shown), each lateral groove can for example be hollowed out of the body 1 of said bearing, along at least one portion of the circumference of the cavity formed by the inner surface of said bearing, each one bordering one of the lateral sides (i.e. along the axis A) of said bearing and limiting said inner surface laterally. As shown in
The bearing according to the invention can include several injectors designed to supply the upper face 11 of the pads 2 with lubricant, as well as several deflectors to manage the flow of lubricant over said upper face 11. Preferably, said injectors and deflectors are paired to form said injection/deflection device 13. According to this preferred embodiment, the bearing according to the invention thus includes a set of injection/deflection devices 13 distributed uniformly (i.e. the circumferential length separating two injection/deflection devices from each other is constant) in relation to the circumference of the cavity of the bearing.
As shown in
Said first portion 131 of the injection/deflection device is designed to be positioned upstream of the second portion 132 in relation to the direction of rotation w of the rotary shaft when the injection/deflection device is installed in said space 12. The first portion 131 in particular includes a portion characterized by a triangular section ST with an apex S that is designed to point radially toward the cavity of said bearing, as shown in
Preferably, said second portion 132 includes a cavity forming a channel 134 extending over the entire length along said axis A of said second portion 132, said channel 134 communicating via the radial opening 14 with a lubricant supply and opening out via orifices 135 into said cavity, for example substantially at said lubrication surface 140 in order to supply lubricant to an interstice formed between the active surface of the pads and the rotary shaft. In particular, each of said orifices 135 opens out into a conduit 136 hollowed out of said lubrication surface 140 of said second portion 132.
Preferably, said lubrication surface 140 is substantially flat and includes said extension 133 that at least partially overhangs said first portion 131 of triangular section ST. According to this embodiment, said conduit 136 is positioned downstream of said extension 133 when said injection/deflection device is installed in a space 12 between two consecutive pads. In particular, the upstream end of said extension 133 is at the same level as the active surface of the closest pad and the downstream end of said lubrication surface 140 is positioned slightly below said active surface of the closest pad, i.e. further away from the rotary shaft than the active surface of the closest pad.
In conclusion, the present invention proposes a new type of hydrodynamic bearing including pads 2 with a reduced active surface where said pads are fitted to a passive sector of said bearing. Optionally, an elastic system couples said pads such as to stabilize the rotation of said bearing, and removable injection/deflection devices 13 that can be inserted between said pads 2 firstly enable lubricant to be injected into an interstice between the active surface of the pad and the rotary shaft, and secondly to divert a lubricant flow toward lateral grooves or slots 15 such that the lubricant heated during the work of the rotary shaft is guided toward said lateral grooves 15 to be drained out of said bearing.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16290090 | May 2016 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/060987 | 5/9/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/202598 | 11/30/2017 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20190136907 A1 | May 2019 | US |
