Propulsion assembly
The propulsion assembly with co-rotating and contra-rotating epicyclic gear trains with identical components addresses the complexity of twin-engine aircraft gearboxes, optimizing parts commonality and reducing costs while maintaining performance.
Patent Information
- Application Number
- PCT/FR2025/050763
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-08-27
- Filing Date
- 2025-08-20
- Publication Date
- 2026-03-05
AI Technical Summary
Conventional twin-engine aircraft with contra-rotating propellers require two different gearbox designs due to opposite propeller rotations, complicating manufacturing and maintenance, and newer turbofan engines with high bypass ratios incorporate additional mechanical gearboxes, increasing complexity and cost.
A propulsion assembly using two reducers of the same dimensions and reduction ratio, comprising co-rotating and contra-rotating epicyclic gear trains with identical components, allowing for opposite propeller rotations without additional gearboxes, and enabling common parts across engines.
Optimizes the number of parts common to both engines, maintaining size, weight, and performance while simplifying manufacturing and reducing costs by minimizing different parts, and allowing for reversed propeller rotation using identical components.
Smart Images
Figure FR2025050763_05032026_PF_FP_ABST
Abstract
Description
DESCRIPTION TITLE: PROPULSIVE SET TECHNICAL FIELD OF THE INVENTION
[0001] The technical field of the invention is that of aeronautics and more particularly that of propulsion systems for twin-engine aircraft.
[0002] The present invention relates in particular to propulsion assemblies comprising two turbomachine-type engines arranged on each side of an aircraft and driving contra-rotating propellers. TECHNOLOGICAL BACKGROUND OF THE INVENTION
[0003] The propellers of most conventional twin-engine aircraft rotate clockwise (viewed from the rear of the engine). Contra-rotating propellers generally rotate clockwise on the left engine and counterclockwise on the right engine.
[0004] The advantage is that counter-rotating propellers balance the effects of torque and thrust asymmetry.
[0005] The disadvantages of contra-rotating propellers stem from the fact that reversing a propeller's rotation requires either an additional reversing gearbox or the engines themselves to be adapted to rotate in opposite directions. This essentially means there are two engine designs: one with left-handed rotating parts and the other with right-handed rotating parts, which complicates manufacturing and maintenance.
[0006] A gearbox is placed in the motor to reverse the direction of rotation of the blower without affecting the compression section and the turbine. The role of the mechanical gearbox is to modify the speed and torque ratio between the input and output shafts of a mechanical system.
[0007] Newer generations of turbofan engines, particularly those with very high bypass ratios, incorporate a mechanical gearbox to drive the fan shaft. Typically, the gearbox's purpose is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan shaft.
[0008] Such a reduction gear comprises a central pinion, called the sun gear, a ring gear, and pinions called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called the planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal X-axis of the turbomachine. The planet gears each have a different axis of revolution, equally spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal X-axis.
[0009] Today, the configuration of a pair of propellers on each wing rotating in opposite directions requires two different gearboxes, one with additional components to reverse the propeller rotation.
[0010] To improve aircraft performance with unfaired engines, it is advantageous to rotate the propulsion unit in different directions from one engine to another, while maintaining the same overall size, weight, and efficiency. In such solutions, and to optimize costs and industrial processes, it is also necessary to minimize the number of different parts from one engine to another. SUMMARY OF THE INVENTION
[0011] The invention offers a solution to the problems mentioned above, by making it possible to optimize the number of parts common to both engines while maintaining the same size, weight and performance.
[0012] One aspect of the invention relates to a propulsion assembly comprising two reducers of the same dimensions and the same reduction ratio, said propulsion assembly comprising: a co-rotating reducer comprising an input epicyclic gear train in series with an output epicyclic gear train, a contra-rotating reducer comprising an input epicyclic gear train in series with an output epicyclic gear train, each epicyclic gear train comprising a sun gear, satellites, a satellite carrier and a ring gear, each reducer comprising an input on a sun gear of the input epicyclic gear train, Each reducer has the output of its input train connected to the solar of its output train, the solars, satellites and satellite carriers of the epicyclic input trains being identical.
[0013] A "co-rotating reducer" is a reducer whose input and output rotate in the same direction, and a "contra-rotating reducer" is a reducer whose input and output rotate in opposite directions. Planetary, epicyclic, and differential reducers, whether single-stage or double-stage, are all referred to as "epicyclic gear trains."
[0014] Using two epicyclic gear trains in series allows for reversing the direction of rotation of one of the motors, unlike a single-train solution. The input epicyclic gear trains include at least two identical components between the two co-rotating and counter-rotating gearboxes; only the choice of fixed components differs. Identical components are defined as those of identical size with identical gear teeth, regardless of whether they are fixed or moving.
[0015] According to a first embodiment the assembly comprises: the co-rotating reducer having the planetary doors of the input epicyclic train and the output epicyclic train fixed, the input epicyclic train is connected by the ring to the solar of the output epicyclic train, the contra-rotating reducer having the ring of the input epicyclic train fixed and the planetary carrier of the output epicyclic train fixed, the input epicyclic train is connected by the planetary carrier to the solar of the output epicyclic train the rings of the input epicyclic trains being identical and, the rings of the output epicyclic trains being identical.
[0016] In this embodiment, four parts of the epicyclic gear trains are identical: three input and one output. The advantage of having fixed planetary gears is that pipes can be run through them to supply power to components, such as those used to orient the blades.
[0017] Advantageously, the output shafts of the co-rotating reducer and the output shafts of the contra-rotating reducer have a number of teeth Zs such that:
[0018] [Math. 1]
[0019] In this way we maintain the GR reduction ratio between the two co-rotating and counter-rotating reducers.
[0020] According to a second embodiment, the assembly comprises: the counter-rotating reducer having the ring gear of the input epicyclic gear train and the planet carrier of the output epicyclic gear train fixed, the input epicyclic gear train is connected by the planet carrier to the solar element of the output epicyclic gear train; the co-rotating reducer having the planet carrier of the input epicyclic gear train and the ring gear of the output epicyclic gear train fixed, the input epicyclic gear train is connected by the planets to the solar element of the output epicyclic gear train.
[0021] In this embodiment, the input epicyclic gear train of the corotatory reducer does not include a ring gear, which simplifies its manufacture. The shaft, planet carrier, and planet gears are identical in the input trains of both reducers. The sun gear, planet carrier, planet gears, and ring gear are identical in the output trains of both reducers.
[0022] According to a third embodiment, the assembly comprises: the co-rotating reducer having the ring gear of the input epicyclic gear train fixed and the ring gear of the output epicyclic gear train fixed, the input epicyclic gear train is connected by the planet carrier to the solar of the output epicyclic gear train; the contra-rotating reducer having the ring gear of the input epicyclic gear train fixed and the ring gear of the output epicyclic gear train fixed, the input epicyclic gear train is connected by the ring gear to the solar of the output epicyclic gear train, the ring gears of the input epicyclic gear trains being identical.
[0023] According to a fourth embodiment, the assembly comprises: the co-rotating reducer having the planet carrier of the input epicyclic gear train and the planet carrier of the output epicyclic gear train fixed, the input epicyclic gear train is connected by the crown to the solar element of the output epicyclic gear train, the contra-rotating reducer having the fixed crown of the input epicyclic gear train and the fixed planet carrier of the output epicyclic gear train, the input epicyclic gear train is connected by the planet carrier to the solar of the output epicyclic gear train the crowns of the input epicyclic gear trains being identical.
[0024] Advantageously, epicyclic gear trains are single-stage. These trains are simpler and less axially bulky.
[0025] Advantageously, epicyclic gear trains are double-staged. This allows for an increased overall reduction ratio. With two single stages, a reduction ratio of around 10 can be achieved, while with two double stages, it can reach up to 100.
[0026] Advantageously, the input and output trains of a gearbox are reversed. The positioning of the trains can be reversed within the same gearbox; that is, the input train is replaced by the output train, and the output train by the input train.
[0027] Advantageously, the trains include straight, helical or herringbone gears.
[0028] For all variants: Therefore, all the gears of the input gear, the planet carrier and the ring gear of the output gear, or the solar element of the output gear, are identical. That is, all the gears of the output gear, the planet carrier and the ring gear of the input gear or the solar element of the input gear are identical.
[0029] Another aspect of the invention relates to an aircraft comprising a propulsion assembly with at least one of the preceding characteristics.
[0030] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES
[0031] The figures are presented as an example and in no way limit the invention.
[0032] [Fig. 1] is the external view of an airplane,
[0033] [Fig. 2] is a schematic view of a reducer according to the invention,
[0034] [Fig. 3] is a cross-section of a counter-rotating reducer according to a first example of the invention,
[0035] [Fig. 4] is a cross-section of a co-rotating reducer according to a first example of the invention,
[0036] [Fig. 5] is a schematic view of a counter-rotating reducer according to a second example of the invention,
[0037] [Fig. 6] is a schematic view of a co-rotating reducer according to a second example of the invention,
[0038] [Fig. 7] is a schematic view of a counter-rotating reducer according to a third example of the invention,
[0039] [Fig. 8] is a schematic view of a co-rotating reducer according to a third example of the invention,
[0040] [Fig. 9] is a schematic view of a counter-rotating reducer according to a fourth example of the invention,
[0041] [Fig. 10] is a schematic view of a co-rotating reducer according to a fourth example of the invention. DETAILED DESCRIPTION
[0042] Unless otherwise specified, the same element appearing on different figures has a unique reference.
[0043] Throughout this description, the front part of the aircraft in the direction of flight will be referred to as "front" and the rear part of the aircraft as "rear".
[0044] Aircraft 1 comprises two wings 10, each equipped with an engine 11, distributed as a right engine 11D and a left engine 11G, as seen from the rear of aircraft 1.
[0045] Each motor 11 comprises an input shaft 3, a reducer 2 and an output shaft 4. According to the invention, the reducer 2 comprises an input epicyclic gear train 20 connected to the input shaft 3 and in series with an output epicyclic gear train 21 connected to the output shaft 4.
[0046] In the first embodiment illustrated in figure 3, the contra-rotating reducer 2G consists of two epicyclic gear trains in series: an input gear 20 and an output gear 21.
[0047] The input train 20 comprises a solar array 50, satellites 51, a satellite carrier 52, and a ring 53. The output train 21 comprises a solar array 60, satellites 61, a satellite carrier 62, and a ring 63. The ring 53 of the input train 20 and the satellite carrier 62 of the output train 21 are fixed. The satellite carrier 52 of the input train 20 is connected to the solar array 60 of the output train 21.
[0048] The input shaft 3 is connected to the solar element 50 and rotates in a direction that will be called positive in this description. Since the ring gear 53 is fixed, the output of the input train is via the planet carrier 52, which also rotates in the positive direction. As the planet carrier 52 is connected to the solar element 60 of the output train 21, the latter also rotates in the positive direction. Because the planet carrier 62 is fixed, it drives the ring gear 63 in the opposite direction (negative direction). The ring gear 63 is connected to the output shaft 4, which therefore rotates in the negative direction.
[0049] In the first embodiment illustrated in figure 4, the 2D corotative reducer consists of two epicyclic gear trains in series: an input gear 20 and an output gear 21.
[0050] The input train 20 comprises a solar array 50, satellites 51, a satellite carrier 52' and a ring 53. The satellite carrier 52' is identical to the satellite carrier 52 except for the link with the solar array 60. The output train 21 comprises a solar array 60', satellites 61', a satellite carrier 62' and a ring 63.
[0051] To keep the same reduction ratio between the two reducers 11, the satellites 61 of the output train 21 of the contra-rotating reducer 2G are of smaller diameter than the satellites 61' of the output train 21 of the co-rotating reducer 2D, and the satellite carrier 60 of the output train 21 of the contra-rotating reducer 2G are of larger diameter than the satellite carrier 60' of the output train 21 of the co-rotating reducer 2D.
[0052] The teeth of the solar gear 50, the satellite gears 51, the satellite gates 53 and the ring gear 53 of the input train and the ring gear of the output train can be identical on both 2D and 2G reducers, with a number Zs of teeth of the solar gears of the two output trains 21 to maintain the reduction ratio (GR) between the two reducers 2A and 2B such that:
[0053] [Math 2]
[0054] Where Zssortie.co is the number of teeth of the solar of the output train of the co-rotating 2D reducer and Zssortie.contra is the number of teeth of the solar of the output train of the contra-rotating 2G reducer.
[0055] The satellite gates 53 of the input train 20 and 62 of the output train 21 are fixed. The ring 53 of the input train 20 is connected to the solar 60' of the output train 21.
[0056] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the planet carrier 52' is fixed, the input train output is via the ring gear 53, which rotates in a negative direction. As the ring gear 53 is connected to the solar element 60' of the output train 21, the latter also rotates in a negative direction. The planet carrier 62 being fixed, it drives the ring gear 63 in the opposite direction (positive direction). The ring gear 63 is connected to the output shaft 4, which therefore rotates in a positive direction.
[0057] The second embodiment is illustrated in Figures 5 and 6. The 2G counter-rotating reducer, visible in Figure 5, consists of two epicyclic gear trains in series: an input train 20 and an output train 21. The teeth of the sun gears, planet gears, and ring gears can be identical on both reducers, with the exception of the output sun gear and the static ring gear of the output train. The planet carriers can also be common to both reducers.
[0058] The input train 20 of the 2G counter-rotating gearbox comprises a solar element 50, planetary elements 51, a planetary carrier 52, and a ring gear 53. The output train 21 comprises a solar element 60, planetary elements 61, a planetary carrier 62, and a ring gear 63. The ring gear 53 of the input train 20 and the planetary carrier 62 of the output train 21 are fixed. The planetary carrier 52 of the input train 20 is connected to the solar element 60 of the output train 21.
[0059] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the ring gear 53 is fixed, the input train output is via the planet carrier 52, which also rotates in a positive direction. As the planet carrier 52 is connected to the solar element 60 of the output train 21, the latter also rotates in a positive direction. The carrier With satellite 62 fixed, it drives the ring 63 in the opposite direction (negative direction). The ring 63 is connected to the output shaft 4, which therefore rotates in the negative direction.
[0060] The co-rotating reducer of the second embodiment visible in figure 6, consists of two epicyclic gear trains in series: an input gear 20 and an output gear 21.
[0061] The input train 20 comprises a solar array 50, satellites 51, and a satellite carrier 2; it does not include a crown. The output train 21 comprises a solar array 60, satellites 61, a satellite carrier 62, and a crown 63.
[0062] The input train 20 satellite carrier 53 and the output train 21 ring 63 are fixed. The input train 20 satellites 51 are connected to the output train 21 solar 60. The output train 21 solar 60 is connected to the output shaft 4.
[0063] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the planet carrier 52 is fixed, the output of the input train 20 is via the planets 51, which rotate in a negative direction. As the planets 51 are connected to the solar element 60 of the output train 21, the latter rotates in a positive direction. The ring gear 63 is fixed, driving the planet carrier 62 in a positive direction. The planet carrier 62 is connected to the output shaft 4, which therefore rotates in a positive direction.
[0064] The third embodiment, visible in figures 7 and 8, includes a 2G counter-rotating reducer in figure 7 and a 2D co-rotating reducer in figure 8.
[0065] The 2G counter-rotating gearbox consists of two epicyclic gear trains in series: an input train 20 and an output train 21. The input train 20 of the 2G counter-rotating gearbox comprises a sun gear 50, planet gears 51, a planet carrier 52, and a ring gear 53. The output train 21 comprises a sun gear 60, planet gears 61, a planet carrier 62, and a ring gear 63. The ring gear 53 of the input train 20 and the ring gear 63 of the output train 21 are fixed. The planet carrier 52 of the input train 20 is connected to the sun gear 60 of the output train 21.
[0066] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the ring gear 53 is fixed, the input train output is via the planet carrier 52, which also rotates in a positive direction. As the planet carrier 52 is connected to the solar element 60 of the output train 21, the latter also rotates in a positive direction. Because the planet carrier 62 is fixed, it drives the ring gear 63 in the opposite direction (negative direction). The ring gear 63 is connected to the output shaft 4, which therefore rotates in a negative direction.
[0067] The 2G co-rotating gearbox consists of two epicyclic gear trains in series: an input train 20 and an output train 21. The input train 20 of the 2G co-rotating gearbox includes a sun gear 50, planet gears 51, a planet carrier 52, and a ring gear 53. The output train 21 includes a sun gear 60, planet gears 61, a planet carrier 62, and a ring gear 63. The planet carrier 52 of the input train 20 and the ring gear 63 of the output train 21 are fixed. The ring gear 53 of the input train 20 is connected to the sun gear 60 of the output train 21.
[0068] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the planet carrier 52 is fixed, the input train output is via the ring gear 53, which also rotates in a positive direction. As the ring gear 53 is connected to the solar element 60 of the output train 21, the latter also rotates in a positive direction. Because the ring gear 63 is fixed, the solar element 60 drives the planet carrier 62 in a positive direction. The planet carrier 62 is connected to the output shaft 4, which therefore also rotates in a positive direction.
[0069] The fourth embodiment visible in figures 9 and 10, includes a 2G contra-rotating reducer in figure 9 and a 2D co-rotating reducer in figure 10.
[0070] The 2G counter-rotating gearbox consists of two epicyclic gear trains in series: an input train 20 and an output train 21. The input train 20 of the 2G counter-rotating gearbox includes a sun gear 50, planet gears 51, a planet carrier 52, and a ring gear 53. The output train 21 includes a sun gear 60, planet gears 61, a planet carrier 62, and a ring gear 63. The ring gear 53 of the input train 20 and the planet carrier 62 of the output train 21 are fixed. The planet carrier 52 of the input train 20 is connected to the sun gear 60 of the output train 21.
[0071] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the ring gear 53 is fixed, the input train output is via the planet carrier 52, which also rotates in a positive direction. As the planet carrier 52 is connected to the solar element 60 of the output train 21, the latter also rotates in a positive direction. Because the planet carrier 62 is fixed, it drives the ring gear 63 in the opposite direction (negative direction). The ring gear 63 is connected to the output shaft 4, which therefore rotates in a negative direction.
[0072] The 2G co-rotating gearbox consists of two epicyclic gear trains in series: an input train 20 and an output train 21. The input train 20 of the 2G co-rotating gearbox includes a sun gear 50, planet gears 51, a planet carrier 52, and a ring gear 53. The output train 21 includes a sun gear 60, planet gears 61, and a planet carrier 52. satellites 62 and a ring 63. The satellite carrier 52 of the input train 20 and the satellite carrier 62 of the output train 21 are fixed. The ring 53 of the input train 20 is connected to the solar element 60 of the output train 21.
[0073] The input shaft 3 is connected to the solar element 50 and rotates in a positive direction. Since the planet carrier 52 is fixed, the input train output is via the ring gear 53, which also rotates in a positive direction. As the ring gear 53 is connected to the solar element 60 of the output train 21, the latter also rotates in a positive direction. Because the planet carrier 62 is fixed, the solar element 60 drives the ring gear 63 in a positive direction. The ring gear 63 is connected to the output shaft 4, which therefore also rotates in a positive direction.
[0074] The order of trains in a reducer can be reversed without departing from the scope of the present invention.
Claims
DEMANDS
1. Aircraft propulsion unit comprising two reduction gears (2D, 2G) of the same dimensions and the same gear ratio, said propulsion unit comprising: - a co-rotating (2D) reducer comprising an epicyclic input train (20) and in series with an epicyclic output train (21), - a counter-rotating reducer (2G) comprising an input epicyclic gear train (20) and in series with an output epicyclic gear train (21), - each epicyclic train (20, 21) comprising a solar element (50, 60), satellites (51, 61), a satellite carrier (52, 62) and a crown (53, 63), - each reducer (2D, 2G) comprising an input on a solar element (50) of the input epicyclic gear train (20), - each reducer (2D, 2G) has the output of its input train (20) connected to the solar (60) of its output train (21 ), - the solar elements (50), the satellite elements (51) and the satellite carriers (52) of the input epicyclic trains (20) being identical.
2. Assembly according to claim 1, characterized in that it comprises: - the co-rotating reducer (2D) having the planet carrier (62) of the input epicyclic gear train (20) and the planet carrier (62) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the ring gear (53) to the sun gear (60) of the output epicyclic gear train (21), - the counter-rotating reducer (2G) having the ring gear (53) of the input epicyclic gear train (20) fixed and the planet carrier (62) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the planet carrier (52) to the sun gear (60) of the output epicyclic gear train (21), - the crowns (53) of the input epicyclic gear trains (20) being identical, the crowns (63) of the output epicyclic trains (21) being identical.
3. Assembly according to the preceding claim, characterized in that the solar elements (60) of the output train (21) of the co-rotating reducer (2D) and the solar elements (60) of the output train (21) of the counter-rotating reducer (2G) have a number of teeth Zs such that:
4. Assembly according to claim 1, characterized in that it comprises: - the counter-rotating reducer (2G) having the ring gear (53) of the input epicyclic gear train (20) and the planet carrier (62) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the planet carrier (52) to the sun gear (60) of the output epicyclic gear train (21), - the co-rotating reducer (2A) having the planet carrier (52) of the input epicycloidal train (20) and the ring (63) of the output epicycloidal train (21) fixed, the input epicycloidal train (20) is connected by the planets (51) to the solar (60) of the output epicycloidal train (21).
5. Assembly according to claim 1, characterized in that it comprises: - the co-rotating reducer (2D) having the ring (53) of the input epicyclic gear train (20) and the ring (63) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the planet carrier (52) to the sun gear (60) of the output epicyclic gear train (21), - the counter-rotating reducer (2G) having the planet carrier (52) of the input epicyclic gear train (20) and the ring gear (63) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the ring gear (53) to the sun gear (60) of the output epicyclic gear train (21), - the crowns (53) of the input epicyclic trains (20) being identical.
6. Assembly according to claim 1, characterized in that it comprises: - the co-rotating reducer (2D) having the planet carrier (52) of the input epicyclic gear train (20) and the planet carrier (62) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the ring gear (53) to the sun gear (60) of the output epicyclic gear train (21), - the counter-rotating reducer (2G) having the planet carrier (52) of the input epicyclic gear train (20) fixed and the ring gear (63) of the output epicyclic gear train (21) fixed, the input epicyclic gear train (20) is connected by the ring gear (53) to the sun gear (60) of the output epicyclic gear train (21 ), - the crowns (53) of the input epicyclic trains (20) being identical.
7. Assembly according to any one of the preceding claims, characterized in that the epicyclic trains (20, 21) are single-stage.
8. Assembly according to any one of claims 1 to 5, characterized in that the epicyclic trains (20, 21) are double-stage.
9. Assembly according to any one of the preceding claims, characterized in that the input trains (20) and output trains (21) of a reducer (2D, 2G) are reversed.
10. Aircraft (1) comprising a propulsion assembly according to one of the preceding claims.