Compound mechanical reduction gear for an aircraft turbine engine
Patent Information
- Application Number
- PCT/FR2026/050154
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-28
- Filing Date
- 2026-02-20
- Publication Date
- 2026-09-03
Smart Images
Figure FR2026050154_03092026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] TITLE: COMPOUND-TYPE MECHANICAL REDUCER FOR AN AIRCRAFT TURBOMACHINE
[0003] Technical field of the invention
[0004] The present invention relates to a compound type mechanical reducer for an aircraft turbomachine, as well as an aircraft turbomachine comprising such a reducer.
[0005] Technical background
[0006] The technical background includes documents FR-A1-3 127 269, FR-A-1 107990 and DE-A1-102019 116090.
[0007] The role of a mechanical reducer is to modify the speed and torque ratio between the input shaft and the output shaft of a mechanical system.
[0008] Aircraft equipped with turboprop engines are generally fitted with a mechanical gearbox (PGB = Propeller Gear Box) that allows for adjusting the rotational speeds between the turbine and the propeller while also creating an offset between the propeller and turbine rotation axes. This offset allows for proper integration of the air intake beneath the gearbox.
[0009] To improve the performance and efficiency of these turboprop engines during certain flight phases (takeoff, taxiing, etc.), several solutions are possible. One such solution involves hybridizing the turboprop by adding an electric motor (in motor mode) to the gearbox to provide additional power during these flight phases. It is also possible to use this electric motor (in generator mode) to recover energy during certain flight phases. Several gearbox architectures exist. Currently, gearboxes are of the planetary type with offset or epicyclic type with offset. There are also compound gearbox architectures.
[0010] - on a planetary offset reducer, the planet carrier is fixed and the ring forms the output shaft of the device which rotates in the opposite direction to the sun.
[0011] - on an epicyclic reducer, the ring is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.
[0012] - on a compound reducer, there are no satellites or satellite carriers and the power is divided over several parallel transmission lines. An epicyclic offset gearbox 10 is illustrated in Figure 1. This gearbox 10 comprises a pinion 12 with an input shaft 14 formed by an electric motor or an output shaft of a turbine M. This pinion 12 meshes with a wheel 16, which in turn drives a central pinion called the sun gear 18, which meshes with pinions called planet gears 20, which are themselves engaged with a ring gear 22. The planet gears 20 are held by a frame called the planet carrier 24. The sun gear 18, the ring gear 22, and the planet carrier 24 are planetary gears because their axes of revolution coincide with the longitudinal axis X of the propeller 26, which forms an output shaft 28. The planet gears 20 have different axes of revolution Y, equally distributed over the same operating diameter around the axis of the planet gears.These Y axes are parallel to the longitudinal X axis.
[0013] A compound gearbox 110 is illustrated in Figure 2. This gearbox 110 comprises a pinion 112 of an input line 114 formed by an electric motor or an output shaft of a turbine M. This pinion 112 meshes with a first set of teeth 130 of two intermediate gears 132 (called idlers) which transmit power. The intermediate gears 132 then drive an output line 128 via a second set of teeth 134 of the intermediate gears 132. By varying the number of teeth on the teeth 130, 134 of the gears 132, it is possible to obtain a speed reduction ratio between the input line 114 and the output line 128 formed by the propeller 126.
[0014] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic fields. Several types of contact meshing exist, including spur, helical, and herringbone gears.
[0015] In current technology, offset gearboxes are relatively bulky and do not allow, or only with great difficulty allow, the passage of utility lines through them. In this application, utility lines are defined as connecting or linking elements of a fluid or electrical type, for example. These could include fluid lines or electrical cables, for instance.
[0016] The invention proposes an improvement to current technologies which makes it easier on the one hand to integrate a compound reducer by limiting its size, and on the other hand to allow the passage of servicing through the reducer.
[0017] Summary of the invention
[0018] The invention relates to a compound-type mechanical gearbox for an aircraft turbomachine, this gearbox comprising:
[0019] - an input pinion centered on a first axis and free to rotate around the first axis to form an input line,
[0020] - a ring centered on a second axis and rotating around the second axis to form an output line, the first and second axes being parallel and spaced apart, and
[0021] - a first pair of intermediate gears for transmitting torque between the input line and the output line,
[0022] characterized in that it further comprises:
[0023] - a second pair of intermediate gears for transmitting torque between the input line and the output line, each of the intermediate gears in the first pair having a first set of teeth for coupling to the input gear, and a second set of teeth,
[0024] each of the intermediate gears of the second pair having a first set of teeth meshing with the second set of teeth of one of the gears of the first pair, and a second set of teeth meshing with an internal set of teeth of the ring gear, a first line of torque transmission between the input line and the output line being formed by one of the intermediate gears of the first pair and one of the gears of the second pair, and a second line of torque transmission between the input line and the output line being formed by the other of the intermediate gears of the first pair and the other of the gears of the second pair,
[0025] and in that the reducer includes a first plane which passes through the first and second axes, between the two torque transmission lines, and which is a plane of symmetry of the reducer.
[0026] The invention proposes a particular and optimized arrangement of transmission lines to facilitate the integration of the reducer and to allow in particular the passage of servicing lines through the reducer.
[0027] The reducer is of the compound type and includes two torque transmission lines, between the input line and the output line.
[0028] The gearbox is configured to have a first plane of symmetry passing through the axes of rotation of the input and output lines. The transmission lines are located on either side of this first plane and arranged symmetrically with respect to it. The symmetry of the gearbox is therefore understood as the symmetrical arrangement of the gearbox's transmission lines on either side of the plane.
[0029] The gearbox is preferably configured to have a second plane passing through the axis of rotation of the output shaft and through the intermediate gears of the second pair. This means that these intermediate gears are located on either side of the second axis of the output shaft and are diametrically opposed with respect to this second axis. This configuration is advantageous for achieving the desired size and also optimizes the gearbox's efficiency.
[0030] The solution proposed below is compatible with multi-stage gearboxes. It is also compatible with spur, helical, or herringbone gears. Furthermore, it is compatible with any type of bearing, whether composed of rolling elements, a hydrodynamic bearing, etc.
[0031] The reducer according to the invention may comprise one or more of the following features, taken individually or in combination with each other:
[0032] - the reducer includes a second plane which is perpendicular to the first plane and which passes through the second axis and through the axes of rotation of the intermediate gears of the second pair;
[0033] - said second plane passes through the second axis and through the axes of rotation of the intermediate gears of the second pair;
[0034] - said second plane passes through the second axis and is away from the axes of rotation of the intermediate gears of the second pair;
[0035] -- said second plane forms an angle of less than 10° with a plane passing through the second axis and through each of the axes of rotation of the intermediate gears of the second pair;
[0036] -- the sprockets of the first pair are identical, and the sprockets of the second pair are identical;
[0037] - the first tooth of each of the intermediate gears of the first pair is meshed with an external tooth of the input gear; in this case, the input and output lines rotate in the same direction of rotation around their respective axes;
[0038] - the first tooth of each of the intermediate gears of the first pair is meshed with an external tooth of the input gear by means of an additional gear common to both transmission lines and having an axis of rotation located in said plane of symmetry; in this case, the input and output lines rotate in different directions of rotation around their respective axes;
[0039] - the first tooth of each of the intermediate gears of the first pair is meshed with a first tooth of the additional gear which includes a second tooth meshed with the external tooth of the input gear;
[0040] - the first set of teeth of each of the intermediate gears of the first pair comprises two rows of teeth situated on either side of another plane perpendicular to the first axis, and the second set of teeth of each of the intermediate gears of the first pair comprises two rows of teeth situated on either side of this other plane and separated from each other by the two rows of teeth of this first set of teeth;
[0041] - the first set of teeth of each of the intermediate gears of the second pair comprises two rows of teeth, and the second set of teeth of each of the intermediate gears of the second pair comprises two rows of teeth axially separated from the rows of teeth of this first set of teeth; - the input gear and the intermediate gears of the first pair are located entirely outside the ring gear, and the intermediate gears of the second pair are partly located outside the ring gear and partly located inside the ring gear;
[0042] - the intermediate gears of the first pair and the second pair are partly located outside the ring gear and partly located inside the ring gear; this reduces the size of the reducer; - the input gear is at least partly located inside the ring gear;
[0043] - said second plan separates the reducer into two parts, a first part in which is located the input line, the intermediate gears of the first pair, and one half of each of the intermediate gears of the second pair, and a second part in which is located the other half of each of the intermediate gears of the second pair, and no other gears;-- at least one servitude crosses axially the ring, passing through said second part;
[0044] - all the gears are guided in rotation by roller bearings, each of the gears having a first axial end guided by a first roller bearing, and a second axial end guided by a second roller bearing;
[0045] - all the gears are guided in rotation by plain or hydrodynamic bearings;
[0046] -- the input pinion is coupled only with the intermediate pinions of the first pair and therefore not with other intermediate pinions;
[0047] -- the crown gear is coupled only with the intermediate gears of the second pair and therefore not with other intermediate gears;
[0048] -- the reducer is devoid of satellites, which are generally regularly distributed around the first axis.
[0049] The invention further relates to a turbomachine, in particular for an aircraft, comprising at least one reduction gear as described above.
[0050] Brief description of the figures
[0051] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:
[0052] [Fig. 1] Figure 1 is a very schematic view of an epicyclic offset mechanical reducer,
[0053] [Fig. 2] Figure 2 is a very schematic view of a compound mechanical reducer,
[0054] [Fig. 3] Figure 3 is a schematic axial cross-sectional view of a turbomachine of the offset turboprop type,
[0055] [Fig. 4] Figure 4 is a schematic perspective view of a compound-type mechanical reducer according to a first embodiment of the invention,
[0056] [Fig. 5] Figure 5 is a schematic side view of the reducer in Figure 4, [Fig. 6] Figure 6 is a schematic front view of the reducer in Figure 4.
[0057] [Fig. 7] Figure 7 is a schematic axial cross-sectional view of the reducer in Figure 4.
[0058] [Fig. 8] Figure 8 is a schematic perspective view of a compound-type mechanical reducer according to a second embodiment of the invention,
[0059] [Fig. 9] Figure 9 is a schematic front view of the reducer in Figure 8,
[0060] [Fig. 10] Figure 10 is a schematic axial cross-sectional view of the reducer in Figure 8,
[0061] [Fig. 11] Figure 11 is a schematic front view of a compound-type mechanical reducer according to a third embodiment of the invention,
[0062] [Fig. 12] Figure 12 is a schematic axial cross-sectional view of the reducer in Figure 11, and
[0063] [Fig. 13] Figure 13 is a schematic front view of a compound type mechanical reducer according to a fourth embodiment of the invention.
[0064] Detailed description of the invention
[0065] Figures 1 and 2 have been described above.
[0066] Figure 3 illustrates an aircraft turbomachine 1, and in particular an aircraft turboprop, the aircraft being for example an airplane or a helicopter.
[0067] As is known, the turboprop engine comprises a casing 2, a gas turbine 3 including a turbine shaft 4, a propeller 26 including a propeller shaft 5, and a reduction gear 210 configured, on the one hand, to be driven by the turbine shaft 4 at a first speed and, on the other hand, to drive the propeller shaft 5 at a second speed lower than the first speed. In this example, the turbine shaft 4 is driven to rotate at a high speed of approximately 10,000 to 35,000 revolutions per minute, while the propeller shaft 5 is driven to rotate at a reduced speed of approximately 1,000 to 2,500 revolutions per minute. The propeller shaft 5 is connected to the propeller 26.
[0068] The 210 reduction gear allows the propeller 26, 126 to rotate at an optimal speed to allow the movement of the aircraft on which the turboprop 1 is mounted.
[0069] The present invention proposes an optimized 210 reducer, embodiments of which are illustrated in figures 4 and following.
[0070] The 210 reducer is of the compound type.
[0071] A first embodiment of the reducer 210 is illustrated in figures 4 to 7 and includes:
[0072] - an input pinion 212 centered on a first X axis and movable in rotation around the first X axis to form an input line LE, and
[0073] - a 214 ring centered on a second Y axis and movable in rotation around the second Y axis to form an LS output line.
[0074] The first and second axes X, Y are parallel and spaced apart from each other as can be seen in the drawings.
[0075] The 210 reducer includes two LT1, LT2 torque transmission lines between the input line LE and the output line LS.
[0076] In the embodiment of figures 4 to 7, each of the transmission lines LT1, LT2 comprises two intermediate gears 216, 218, which are part of two pairs of gears respectively.
[0077] The 210 reducer thus comprises:
[0078] - a first pair of intermediate sprockets 216, and
[0079] - a second pair of intermediate sprockets 218.
[0080] Each of the intermediate gears 216 has a first tooth 216a for coupling to the input gear 212, and a second tooth 216b. Each of the intermediate gears 218 has a first tooth 218a meshed with the second tooth 216b of one of the gears 216 of the same transmission line LT1, LT2, and a second tooth 218b meshed with an internal tooth 214a of the ring gear 214.
[0081] We define two planes P1, P2 of the reducer 210.
[0082] The first plane P1 passes through the first and second axes X, Y, between the two transmission lines LT1, LT2. This first plane is a plane of symmetry of the reducer 210. We can see in particular that the transmission lines LT1, LT2, are located on either side of the first plane P1 and symmetrically with respect to this first plane P1.
[0083] The second plane P2 passes through the second Y axis and through the intermediate gears 218, which is particularly advantageous for optimizing the efficiency and size of the reducer 210.
[0084] The second plane P2 can pass through the second axis Y and through the axes of rotation of the intermediate gears 218 which are thus diametrically opposed with respect to the second axis Y (figures 4 to 12).
[0085] Alternatively, the second plane P2 can pass through the second Y axis and can be moved away from the Z axes of rotation of the intermediate gears 18 of the second pair (figure 13).
[0086] The second plane P2 preferably forms an angle oc of less than 10° with a plane P4 passing through the second Y axis and through each of the Z axes of rotation of the intermediate gears 218 of the second pair. This allows for a greater latitude in adjustments.
[0087] The gears 216 are preferably identical. The gears 218 are preferably identical. The gears 218 may be oversized compared to the gears 216, as is the case in the example shown. In the embodiment of Figures 4 to 7, the first tooth 216a of each of the gears 216 is directly coupled to the input gear 212 and is, in particular, directly meshed with an external tooth 212a of the input gear 212.
[0088] The input and output lines LE, LS of the reducer 210 rotate in the same direction of rotation around their respective axes X, Y. The first toothing 216a of each of the pinions 216 can comprise two rows of teeth 216a1, 216a2 situated on either side of another plane P3 perpendicular to the first axis X.
[0089] The second toothing 216b of each of the pinions 216 can comprise two rows of teeth 216b1, 216b2 situated on either side of this other plane P3 and separated from each other by the two rows of teeth 216a1, 216a2 of this first toothing 216a.
[0090] The first toothing 218a of each of the pinions 218 can comprise two rows of teeth 218a1, 218a2, and the second toothing 218b of each of the pinions 218 can comprise two rows of teeth 218b1, 218b2. The two rows of teeth 218b1, 218b2 are here axially separated from the rows of teeth 218a1, 218a2 of the first toothing 218a.
[0091] In this embodiment, the input pinion 212 and the intermediate pinions 216 are located entirely outside the ring 214. The intermediate pinions 218 are partly located outside the ring 214 and partly located inside the ring 214.
[0092] The drawings show that the second plane P2 can separate the reducer 210 into two parts: a first part H1 containing the input line LE, the intermediate gears 216, and one half of each of the intermediate gears 218; and a second part H2 containing the other half of each of the intermediate gears 218, and no other gears. At least one service component S can pass axially through the ring gear 214, via this second, free part H2 of the reducer 210.
[0093] All the gears 212, 216, 218 can be guided in rotation by roller bearings 220, each of the gears 212, 216, 218 having a first axial end guided by a first roller bearing 220, and a second axial end guided by a second roller bearing 220. Alternatively, all the gears 212, 216, 218 are guided in rotation by plain or hydrodynamic bearings. Figures 8 to 10 illustrate a second embodiment of the reducer 210 which differs from that of the first embodiment essentially in that the reducer 210 further comprises an additional gear 222 common to the two transmission lines LT1, LT2.
[0094] In this embodiment, the input and output lines LE, LS rotate in different directions around their respective axes X, Y.
[0095] The additional pinion 222 has an axis of rotation located in the plane P1. The additional pinion 222 is thus traversed by the plane P1.
[0096] The first tooth 216a of each of the pinions 216 is meshed with the external tooth 212a of the input pinion 212 via the additional pinion 222.
[0097] More specifically, the first tooth 216a of each of the pinions 216 is meshed with a first tooth 222a of the additional pinion 222 which includes a second tooth 222b meshed with the external tooth 212a of the input pinion 212.
[0098] In the example shown, the second toothing 222b of the pinion 222 can comprise two rows of teeth 222b1, 222b2 located on either side of the aforementioned plane P3.
[0099] The first toothing 222a of the pinion 222 can comprise two rows of teeth 222a1, 222a2 located on either side of the plane P3 and separated from each other by the two rows of teeth 222b1, 222b2.
[0100] The pinion 222 can be guided in rotation by roller bearings 220, and have a first axial end guided by a first roller bearing 220, and a second axial end guided by a second roller bearing 220. Alternatively, the pinion 222 could be guided in rotation by plain or hydrodynamic bearings.
[0101] Figures 11 and 12 illustrate a third embodiment of the reducer 210 which differs from the first embodiment primarily in its axial dimensions, which are minimized here. To achieve this, the pinions 216 are partly located outside the ring gear 214 and partly located inside the ring gear 214. The input pinion 212 is at least partially located inside the ring gear 214.
[0102] We can thus see in the last figure that the aforementioned plane P3 can pass through the middle of all the teeth of the reducer 210.
[0103] The first toothing 218a of each of the pinions 218 can then comprise two rows of teeth 218a1, 218a2 situated on either side of the plane P3. The second toothing 216b of each of the pinions 216 can comprise two rows of teeth 218b1, 218b2 situated on either side of the plane P3 and situated between the two rows of teeth 218a1, 218a2 of this first toothing 218a.
[0104] The invention makes it possible in particular to maximize efficiency by minimizing the size, mass and complexity of a compound type offset reducer for an aircraft turbomachine.
Claims
DEMANDS 1. Mechanical gearbox (210) of the compound type for an aircraft turbomachine, this gearbox (210) comprising: - an input pinion (212) centered on a first axis (X) and movable in rotation around the first axis (X) to form an input line (LE), - a ring (214) centered on a second axis (Y) and rotatable around the second axis (Y) to form an output line (LS), the first and second axes (X, Y) being parallel and spaced apart, and - a first pair of intermediate gears (216) for transmitting torque between the input line (LE) and the output line (LS), characterized in that it further comprises: - a second pair of intermediate gears (218) for transmitting torque between the input line (LE) and the output line (LS), each of the intermediate gears (216) of the first pair having a first set of teeth (216a) for coupling to the input gear (212), and a second set of teeth (216b), each of the intermediate gears (218) of the second pair having a first toothing (218a) meshed with the second toothing (216b) of one of the gears (216) of the first pair, and a second toothing (218b) meshed with an internal toothing (214a) of the ring gear (214), a first line (LT1) of torque transmission between the input line (LE) and the output line (LS) being formed by one of the intermediate gears (216) of the first pair and one of the gears (218) of the second pair, and a second line (LT2) of torque transmission between the input line (LE) and the output line (LS) being formed by the other of the intermediate gears (216) of the first pair and the other of the gears (218) of the second pair, and in that the reducer (210) comprises a first plane (P1) which passes through the first and second axes (X, Y), between the two torque transmission lines (LT1, LT2), and which is a plane of symmetry of the reducer (210).
2. Reducer (210) according to claim 1, in which the reducer (210) comprises a second plane (P2) which is perpendicular to the first plane (P1) and which passes through the second axis (Y) and through the intermediate gears (218) of the second pair.
3. Reducer (210) according to claim 2, in which said second plane (P2) passes through the second axis (Y) and through the axes (Z) of rotation of the intermediate gears (218) of the second pair.
4. Reducer (210) according to claim 2, in which said second plane (P2) passes through the second axis (Y) and is separated from the axes (Z) of rotation of the intermediate gears (218) of the second pair.
5. Reducer (210) according to any one of claims 1 to 4, wherein the first toothing (216a) of each of the intermediate gears (216) of the first pair is meshed with an external toothing (212a) of the input gear (212).
6. Reducer (210) according to any one of claims 1 to 4, wherein the first toothing (216a) of each of the intermediate gears (216) of the first pair is meshed with an external toothing (212a) of the input gear (212) via an additional gear (222) common to both transmission lines (LT1, LT2) and having an axis of rotation (W) located in said plane (P1) of symmetry.
7. Reducer (210) according to claim 7, wherein the first toothing (21 a6) of each of the intermediate gears (216) of the first pair is meshed with a first toothing (222a) of the additional gear (222) which includes a second toothing (222b) meshed with the external toothing (212a) of the input gear (212).
8. Reducer (210) according to any one of the preceding claims, wherein the first toothing (216a) of each of the intermediate gears (216) of the first pair comprises two rows of teeth (216a1, 216a2) situated on either side of another plane (P3) perpendicular to the first axis (X), and the second toothing (216b) of each of the intermediate gears (216) of the first pair comprises two rows of teeth (216b1, 216b2) situated on either side of this other plane (P3) and separated from each other by the two rows of teeth (216a1, 216a2) of this first toothing (216a).
9. Reducer (210) according to any one of the preceding claims, wherein the first toothing (218a) of each of the intermediate gears (218) of the second pair comprises two rows of teeth (218a1, 218a2), and the second toothing (218b) of each of the intermediate gears (2118) of the second pair comprises two rows of teeth (218b1, 218b2) axially separated from the rows of teeth (218a1, 218a2) of this first toothing (218a).
10. A gearbox (210) according to any one of claims 1 to 9, wherein the input pinion (212) and the intermediate pinions (216) of the first pair are located entirely outside the ring gear (214), and the intermediate pinions (218) of the second pair are located partly outside the ring gear (214) and partly inside the ring gear (214).
11. A gearbox (210) according to any one of claims 1 to 9, wherein the intermediate pinions (216, 218) of the first and second pairs are located partly outside the ring gear (214) and partly inside the ring gear (214).
12. Reducer according to claim 11, wherein the input pinion (212) is at least partly located inside the ring gear (214).
13. Reducer (210) according to any one of claims 2 to 4, wherein said second plane (P2) separates the reducer (210) into two parts, a first part (H1) in which is located the input line (LE), the intermediate gears (216) of the first pair, and one half of each of the intermediate gears (218) of the second pair, and a second part (H2) in which is located the other half of each of the intermediate gears (218) of the second pair, and no other gears.
14. Reducer (210) according to any one of claims 1 to 13, in which all the gears (212, 216, 218, 222) are guided in rotation by roller bearings (220), each of the gears (212, 216, 218, 222) having a first axial end guided by a first roller bearing (220), and a second axial end guided by a second roller bearing (220).
15. Reducer (210) according to any one of claims 1 to 14, in which all the gears (212, 216, 218, 222) are guided in rotation by plain or hydrodynamic bearings.
16. Turbomachine (1), in particular aircraft turbomachine, comprising at least one reduction gear (210) according to one of the preceding claims.