Gear train reducer

Abstract

The present invention relates to a gear train reducer, comprising: a radial internal planetary gear capable of pivoting about an axis (X), a radial external annular planetary gear coaxial with the internal planetary gear, and at least one satellite gear meshing with the internal planetary gear and the external planetary gear, the satellite gear being mounted to pivot about an axis belonging to a satellite bracket, characterized in that the satellite gear is formed by a gear extending along an axis (Y) and comprises at least two annular tooth areas and an annular groove, the annular groove being axially located between the tooth areas for collecting lubricating oil from the tooth areas, characterized in that the groove is delimited by an axially extending bottom surface and a radially extending side surface, characterized in that the groove has at least one protrusion extending radially outward from the bottom surface of the groove.

Description

Technical Field

[0001] The invention relates to a gear wheel, in particular intended to form a satellite gear wheel of a gear train reducer, in particular for a turbomachine. Background Art

[0002] like Figure 1 As shown, the aircraft turbine 1 generally includes a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7 in the downstream direction, i.e., the direction of gas flow inside the turbine. The low-pressure compressor 3 is driven to rotate by the low-pressure turbine 7 through a low-pressure shaft 8. The high-pressure compressor 4 is driven to rotate by the high-pressure turbine 6 through a high-pressure shaft 9 coaxial with the low-pressure shaft. The axis of the turbine 1 coincides with the axis of the shafts 8 and 9 and is marked as X. The fan 2 is driven to rotate by the low-pressure shaft 8 via a gear train reducer 10.

[0003] like Figure 2 As shown, such a reducer 10 generally has radially inner planetary gears 11 capable of pivoting about an axis coinciding with the X axis, and radially outer annular planetary gears 12 coaxial with the inner planetary gears 11, and satellite gears 13 meshing with the inner planetary gears 11 and the outer planetary gears 12. Each satellite gear 12 is mounted to pivot about an axis 14 belonging to a satellite gear carrier 15, the geometric axis of which is marked Y.

[0004] The inner planet gears 11 may also be referred to as sun gears. The outer planet gears 12 may also be referred to as crown gears.

[0005] The satellite gear carrier 15 can be fixed, and the crown 12 can rotate. Such a reducer 10 is then of the planetary gear type.

[0006] Alternatively, the crown 12 may be fixed and the satellite gear carrier 15 may be able to rotate. Such a reducer 1 is of the planetary type.

[0007] The low-pressure shaft 8 is usually rotationally coupled to the internal planetary gears 11 , while the shaft 16 of the fan 2 is rotationally coupled to the motion output element of the gear train, ie either to the crown 12 in the case of a planetary gear reducer 10 or to the satellite gear carrier 15 in the case of a planetary reducer 10 .

[0008] The gear train 10 is housed in a housing 17 and is lubricated by an oil supply, notably known in the name of the applicant from document FR 3 047 279. In the following description, we will focus in particular on the lubrication of the satellite gears 13 and / or the inner planetary gears 11 .

[0009] It is known to use satellite gears 13 and internal planetary gears 11 with herringbone gears, such as Figure 3 and4 shown.

[0010] Each satellite gear 13 then takes the form of a gear or pinion, the body of which comprises a central hole having a geometric axis Y for mounting the satellite gear on the axis of the satellite gear carrier.

[0011] In the following, the terms "axial" and "radial" are defined relative to the X-axis.

[0012] The body comprises a first tooth region 18 and a second tooth region 19 which are axially spaced from one another and delimit between them an annular groove 20 having a rectangular or square cross section.

[0013] The recess 20 is thus delimited by a cylindrical bottom wall 21 and two radial side walls 22 formed by the respective axial ends of the toothed areas 18, 19. The bottom wall 21 is located radially on the inside of the bottom of the areas 18, 19 with respect to the toothed portions.

[0014] The toothed areas 18, 19 form a herringbone gear. In other words, the two toothed areas 18, 19 each have two helical teeth of equal size but with opposite helices in order to cancel out axial forces acting on the assembly.

[0015] In operation, low temperature lubricating oil is supplied to the teeth of each satellite gear 13 where they are heated. Due to the shape and orientation of the teeth, the hot oil from the teeth then enters the grooves 20. Figure 4 As shown by the arrow in , the oil is discharged from the groove 20 by centrifugation.

[0016] In practice, it is difficult to control the position and axial size of the oil drainage area. Indeed, the sidewalls 22 of the groove 20 form a surface discontinuity that facilitates the separation of some of the oil. In addition, it has been found that, over the entire axial size of the groove 20, the oil also falls off from the bottom surface 21 of the groove 20.

[0017] It is important to control the radially outward axial position of the hot oil expelled by centrifugal action to prevent it from lubricating other surrounding tooth areas. Indeed, since the oil is already hot, its lubricating and heat absorption capacity is low, thereby reducing the efficiency of this lubrication.

[0018] In addition, the oil sprayed from the satellite gears can wet surfaces that do not necessarily need lubrication, thereby increasing the amount of oil required for lubrication. However, this amount of oil is determined by the capacity of the oil tank, the size of which is limited by the space available inside the turbine.

[0019] In addition, the collector (in Figure 2The collectors (shown in dashed lines) can be arranged circumferentially between the satellite gears, and these collectors are responsible for collecting part of the lubricating oil from the satellite gears. Controlling the axial position of the lubricating oil spraying area will make it possible to optimize and reduce the size and mass of these collectors.

[0020] The present invention aims to remedy these various limitations in a simple, reliable and inexpensive manner. Summary of the invention

[0021] To this end, the invention relates to a gear which extends along an axis and comprises at least two annular tooth areas and an annular groove which is axially located between the tooth areas and is used to collect lubricating oil from the tooth areas, characterized in that the groove is delimited by an axially extending bottom surface and radially extending side surfaces, characterized in that the groove comprises at least one protrusion which extends radially outwards from the bottom surface of the groove.

[0022] The present invention relates to a gear train reducer, comprising: a radially inner planetary gear capable of pivoting about an axis X, a radially outer annular planetary gear coaxial with the inner planetary gear, at least one satellite gear meshing with the inner planetary gear and the outer planetary gear, the satellite gear being mounted to pivot about an axis belonging to a satellite bracket, characterized in that the satellite gear is formed by a gear extending along an axis Y and comprises at least two annular tooth areas and an annular groove, the annular groove being axially located between the tooth areas for collecting lubricating oil from the tooth areas, characterized in that the groove is delimited by an axially extending bottom surface and a radially extending side surface, characterized in that the groove has at least one protrusion extending radially outward from the bottom surface of the groove.

[0023] The protrusions are thus able to create a geometric discontinuity, thereby causing the oil film contained in the groove to separate, so that the oil is discharged radially outwards under the action of the centrifugal force generated during operation. Since the axial position of the protrusions is known, the axial position of the sprayed oil can be controlled, thereby preventing such oil from reaching or excessively reaching elements in the gear environment that do not require oil.

[0024] Thus, hot oil is not supplied to the elements to be cooled. In addition, it is also avoided that oil is supplied to elements of the environment where lubrication is not necessary. This limits the volume of oil to be used, which makes it possible to reduce the size of the oil tank required for supplying the lubricating oil.

[0025] In the case of using a collector to recover all or part of the oil sprayed from the gear, axial control of the injection position allows the collector to be optimally dimensioned so as to limit in particular its mass and dimensions.

[0026] The protruding portion may have at least one radially outer vertex, the at least one radially outer vertex forming a kink of a surface of the protruding portion.

[0027] The formation of a knurl, i.e. an abrupt or discontinuous change in the slope of the surface formed by the protrusion, facilitates the separation of the oil film. This ensures that most of the oil film in the groove is separated in the radial plane of the knurl. The knurl is convex because it forms a convex area rather than a concave area.

[0028] The protruding portion may be symmetrically shaped with respect to a radial plane, for example, located in an axially middle region of the groove.

[0029] The apex may lie in or be centered on the radial plane. For example, where there are two apexes, these may lie symmetrically with respect to the median plane on either side of the axial median radial plane.

[0030] Of course, the radial plane may be located at other positions than the center of the groove.

[0031] The protruding portion may axially include at least one inclined region gradually extending radially outward from one tooth ring region to the other tooth ring region, a region forming a radially outer apex, and at least one inclined region gradually extending radially inward.

[0032] The inclined region is defined as a region whose radially outward surface is inclined with respect to both the radial direction and the axial direction.

[0033] Each inclined region may be flat, concave or convex.

[0034] The protruding portion may be annular.

[0035] Therefore, the protruding portion extends continuously over the entire circumference of the groove.

[0036] Alternatively, the protrusion can be discontinuous and extend in an angular sector around the circumference of the groove. In this case, the angular sectors can be evenly distributed on the circumference, thereby avoiding imbalance during operation.

[0037] The two tooth regions may form a herringbone gear.

[0038] As mentioned above, herringbone gears have two helical tooth sections, usually of the same size, but with oppositely directed spirals to counteract the axial forces applied to the gear. A central groove then allows the cutting tool to be easily disengaged at the intersection of the two spirals, and the groove also serves to drain lubricant.

[0039] In other words, in this case the teeth of the first toothed area are inclined relative to the axis of the gear in a first direction and the teeth of the second toothed area are inclined relative to the axis in a second direction, the second direction being opposite to the first. Thus, the teeth of both areas define a general V-shape.

[0040] Of course, other types of toothing can be used which are capable of forming a spur gear, i.e. the axes of the elements meshing with each other are parallel. For example, the teeth can be oriented parallel to the axis of the gear. More generally, the invention is applicable to all parallel axis gears having at least two tooth areas separated by one or more grooves.

[0041] The protruding portion may be manufactured integrally with the bottom surface of the groove.

[0042] The protruding portion may be formed from at least one portion that is different from the rest of the gear.

[0043] The separated part may be annular or sector-shaped. The annular or sector-shaped part may be attached to the rest of the gear by a flange or any other suitable means.

[0044] The axial extent of the projection may extend over all or part of the axial extent of the recess.

[0045] The bottom surface of the recess may be cylindrical.

[0046] The apex of the protruding portion may be located radially within the radial outer periphery of the tooth region. In other words, the apex of the protruding portion may be located radially within the groove.

[0047] The radial distance between the bottom and apex of the groove may be between 50% and 100% of the radial dimension or height of the groove.

[0048] An alternative is also conceivable in which the apex of the projection is located radially outside the recess, ie radially outside the radial outer circumference of the tooth region.

[0049] The apex of the projection may lie in a single radial plane, or extend axially over a portion of the axial dimension of the recess.

[0050] The tooth region may be manufactured integrally with the gear body, or may be manufactured as a separate part that is attached to the body.

[0051] The invention also relates to a gear train reducer comprising radial internal planetary gears capable of pivoting about an axis, radial external annular planetary gears coaxial with the internal planetary gears, at least one satellite gear meshing with the internal planetary gears and the external planetary gears, the satellite gears pivoting about an axis belonging to a satellite gear carrier, characterised in that the satellite gears are formed by gears of the above-mentioned type.

[0052] The inner planetary gears can also be called sun gears. The outer planetary gears are also called crown gears.

[0053] The satellite gear carrier can be fixed and the crown can rotate. Such a reducer is of the planetary gear type.

[0054] Alternatively, the crown can be fixed and the satellite gear carrier can rotate. Such a reducer is of the planetary type.

[0055] The invention also relates to a turbomachine, such as an aircraft turbojet or turboprop engine, having a gear train reducer of the above-described type.

[0056] The invention will be better understood when reading the following description and with reference to the appended drawings, and other details, characteristics and advantages of the invention will be given as non-limiting examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] - Figure 1 is a schematic cross-sectional half view of a prior art turbofan engine;

[0058] - Figure 2 is a schematic front view of a portion of a gear train reducer;

[0059] - Figure 3 is a side view of a prior art gear, where a satellite gear is formed;

[0060] - Figure 4 yes Figure 3 a cross-sectional view of a portion of a gear;

[0061] - Figures 5 to 12 is corresponding to Figure 4 , showing different forms of implementation of the gear according to the invention. DETAILED DESCRIPTION

[0062] Figure 5 A gear or satellite gear 13 according to a first embodiment of the invention is shown;

[0063] As previously mentioned, this gear 13 has a body with a central hole having a geometric axis Y for mounting the gear or satellite gear 13 on the axis 14 of the satellite gear carrier 15. The body has a first toothed area 18 and a second toothed area 19 which are axially spaced from each other and delimit between them an annular groove 20 of rectangular cross section.

[0064] The groove 20 is delimited by a bottom 21 and two radial side walls 22 formed by the respective axial ends of the tooth regions 18 , 19 .

[0065] The toothed areas 18, 19 form a herringbone gear. In other words, the two toothed areas 18, 19 each have two helical teeth of equal size but with opposite helices in order to cancel out axial forces acting on the assembly.

[0066] The gear 13 and the reference Figure 3 and Figure 4 The described gear differs in that the groove 20 has a projection 23 extending radially outwards from the bottom of the groove.

[0067] The projection 23 is symmetrical with respect to a median axial plane P passing through the middle of the groove 20. The projection 23 extends over the entire axial dimension or width of the groove 20, so that the bottom wall 21 itself is not visible.

[0068] The protruding portion 23 has two concavely curved side walls 24 situated on either side of the median plane P, and an apex 25 forming a cylindrical portion, the axial dimension of which can be adjusted as required.

[0069] The radially inner end of the concave wall 24 joins the bottom 21 of the groove 20 and the sidewall 22 of the groove 20. The radially outer end of the concave wall 24 reaches an apex 25 which forms a slope break 26, ie a discontinuity or break in the slope.

[0070] The radially inner end of the recessed wall 24 is positioned radially inwardly relative to the bottom of the toothing of the toothing region 18 , 19 , so that oil can flow into the groove 20 .

[0071] The apex 25 is located radially inside the outer periphery of the tooth portion. In other words, the apex 25 is located radially inside the groove 20.

[0072] In operation, the lubricating oil used to lubricate the teeth 18, 19 penetrates into the grooves 20 on either side of the plane P and then flows in the form of a film along the concave surface 24 before being separated from said concave surface 24 and ejected centrifugally by the inflection point 26 at the apex 25. It should be noted that a small part of the oil can also be ejected at the sides 22 of the grooves 20, these surfaces 22 also forming inflection points, which facilitate the shedding of the oil film.

[0073] Checking the axial dimension of the apex 25 makes it possible, if necessary, to axially reduce the injection area at the inflection point 26 of the apex 25 .

[0074] Figure 6 A second embodiment is shown, which is Figure 5 The embodiment shown differs in that the protruding portion 23 has two inclined flat surfaces 24, the radially outer ends of which meet at an apex 25. Each flat surface 24 may be inclined, for example, at an angle between 5 and 75° relative to the Y axis.

[0075] In this embodiment, the axial dimension of the apex 25 is zero, so that the apex 25 is reduced to an annular line forming a kink 26. In this embodiment, the protrusion 23 also extends over the entire width of the groove 20. Each flat surface 24 extends over half the width of the groove 20.

[0076] Figure 7 A third embodiment is shown, which is Figure 6 The embodiment shown differs in that the projection 23 extends only over a portion of the width of the groove 20 .

[0077] Figure 8 A fourth embodiment is shown, which is Figure 6 The embodiment shown differs in that the inclined wall 24 is a concave wall, whose shape is different from the shape of a circular arc and whose profile is designed to ensure the best disengagement of the machining tool from the toothing and / or the guidance and ejection of oil at the vertex 25. The inclined wall 24 can also be formed by two flat parts with different slopes, which are connected or not connected by a circular connecting area.

[0078] Fig. 9 A fifth embodiment is shown, which is similar to the reference Figure 6 The embodiment shown differs in that the axial dimension of the apex 25 is not zero, so that Figure 5 Thus, the protruding portion 23 comprises two inflection points 26 located at the axial ends of the apex 25.

[0079] Fig.10 A sixth embodiment is shown, which is Fig. 9 The embodiment shown differs in that an auxiliary groove 27 is formed in the vertex 25. Here, the auxiliary groove 27 is delimited by a cylindrical bottom surface and two radial side surfaces. The width of the auxiliary groove 27 is smaller than the width of the cylindrical vertex 25. The bottom surface of the auxiliary groove 27 is located radially outward relative to the radial inner end 21 of the flat side wall 24.

[0080] Fig.11 A seventh embodiment is shown, which differs from the embodiments shown above in that the projection 23 has a circular cross section, for example a semicircular cross section. Other forms are also possible. The projection 23 here extends only over a portion of the width of the groove 20. Alternatively, it can extend over the entire width of the groove 20. It should be noted that such a projection 23 does not have a kink 26.

[0081] Fig.12 An eighth embodiment is shown, which is Fig.11The embodiment shown differs in that an auxiliary groove 27 is formed in the apex 25 . The auxiliary groove 27 is here delimited by a cylindrical bottom surface and two radial side surfaces. The bottom surface of the auxiliary groove is located radially outwards relative to the radial inner end 21 of the circular side wall 24 .

[0082] The choice of the shape and size of the projection 23 depends inter alia on the manufacturing method and must allow the machining tool to be disengaged when manufacturing the toothed regions 18 , 19 .

[0083] In each of the above embodiments, the radial distance between the bottom 21 and the apex 25 of the groove 20 may be between 50% and 100% of the radial dimension or height of the groove 20 .

[0084] The protruding portion 23 may be formed of at least a portion separated from the rest of the gear 13 .

[0085] The separated part may be annular or sector-shaped. The annular or sector-shaped part may be attached to the rest of the gear 13 by a flange or any other suitable means.

[0086] Each of the above-described embodiments makes it possible to improve the control of the axial position of the sprayed oil and thus prevent the oil from reaching or excessively reaching the elements of the reducer that do not require oil.

Claims

1. A gear train reducer, comprising: A radially inner planetary gear (11) pivotable about an axis (X), a radially outer annular planetary gear (12) coaxial with the inner planetary gear (11), at least one satellite gear (13) meshing with the inner planetary gear (11) and the outer planetary gear (12), the satellite gear (13) being mounted to pivot about an axis (14) belonging to a satellite carrier (15), characterised in that the satellite gear (13) is formed by a gear (13) extending along an axis (Y) and comprising at least two annular toothed areas (18, 19) and an annular groove (20), the annular groove (20) being axially located between the toothed areas (18, 19) for Lubricating oil is collected from the tooth areas (18, 19), wherein the groove (20) is defined by an axially extending bottom surface (21) and a radially extending side surface (22), wherein the groove (20) has at least one protrusion (23), and the protrusion (23) extends radially outward from the bottom surface (21) of the groove (20); wherein the protrusion (23) axially includes at least one inclined area (24) extending radially outward from one annular tooth area (18, 19) to the other annular tooth area, a region forming a radially outer apex (25), and at least one inclined area (24) extending radially inward.

2. The reducer according to claim 1, characterized in that: The protruding portion (23) has at least one radially outer vertex (25), which forms a kink in the surface of the protruding portion (23).

3. The reducer according to claim 1, characterized in that: The protruding portion (23) has a symmetrical shape relative to the radial plane (P).

4. The reducer according to claim 1, characterized in that: The protrusion (23) has a symmetrical shape relative to a radial plane (P) located in an axially middle region of the groove (20).

5. The reducer according to claim 1, characterized in that: Each inclined region (24) is flat, concave or convex.

6. The reducer according to claim 1, characterized in that: The protruding portion (23) is annular.

7. The reducer according to claim 1, characterized in that: The two toothed areas (18, 19) form a herringbone gear.

8. The reducer according to claim 1, characterized in that: The protruding portion (23) is manufactured integrally with the bottom surface (21) of the groove (20).

9. The reducer according to any one of claims 1 to 8, characterized in that: The protruding portion (23) is formed of at least one portion that is different from the rest of the gear.

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