ELECTRIC DRIVE ARRANGEMENT WITH AT LEAST ONE ELECTRIC MOTOR POSITIONED AT THE FRONT OF A TRANSMISSION SYSTEM, AIRCRAFT COMPLIMENTING WITH AT LEAST SUCH DRIVE ARRANGEMENT

Description

[0001] This application relates to an electric propulsion system comprising at least one electric motor positioned at the front of a transmission system and to an aircraft comprising at least one such propulsion system.

[0002] According to an embodiment visible on the figure 1 An aircraft 10 comprises a fuselage 12, at least one wing 14 connected to the fuselage 12, and propulsion assemblies 16 connected to the wing 14 and arranged on either side of the fuselage 12. As illustrated in the figures 2 et 3 , each propulsion assembly 16 includes a propeller 18 which has an axis of rotation A18.

[0003] For the remainder of this description, a longitudinal direction X is parallel to the axis of rotation A18 of the propeller 18. A longitudinal plane contains the axis of rotation A18. A transverse plane is perpendicular to the longitudinal direction X. A horizontal transverse direction Y is perpendicular to the longitudinal direction X and oriented horizontally. A vertical transverse direction Z is perpendicular to the longitudinal direction X and oriented vertically. The terms "front" and "rear" refer to the direction of airflow relative to the aircraft in flight, with air flowing from front to rear.

[0004] In the case of an electric propulsion system, the latter includes several electric motors 20, a transmission system 22, such as a gearbox for example, configured to couple the electric motors 20 to the propeller 18, and a propeller pitch control system 24 having a control shaft 24.1 connected to the propeller 18.

[0005] The propulsion assembly 16 includes an attachment structure 26 linking the transmission system 22 to an aircraft support structure 10, such as the wing structure for example.

[0006] According to an arrangement visible on the figures 2 et 3 , the transmission system 22 has a first transverse surface 22.1, oriented towards the front, on which is attached a propeller drive shaft 18 and a second transverse surface 22.2, oriented towards the rear, on which are attached the electric motors 20 and the propeller pitch adjustment system 24.

[0007] The control axis 24.1 of the propeller pitch adjustment system 24 being positioned in the extension of the rotation axis A18 of the propeller 18, this propeller pitch adjustment system 24 is positioned in the center of the second transverse surface 22.2 and the electric motors 20 are arranged all around the propeller pitch adjustment system 24.

[0008] Although this arrangement allows for a compact assembly, it is not entirely satisfactory because the 24 propeller pitch adjustment system is difficult to access.

[0009] US2021 / 371120 describes a substantially similar embodiment. According to this document, an aircraft propulsion system comprises a propeller with a rotation axis, several electric motors, and a transmission system configured to couple the electric motors to the propeller. This transmission system includes an output shaft connected to the propeller and a propeller pitch control system, and defines a forward zone in which the propeller is positioned and a rear zone opposite the forward zone, in which the propeller pitch control system is positioned. According to this document, the motors and the propeller pitch control system are aligned one behind the other, which does not result in a compact assembly.

[0010] The present invention aims to remedy all or part of the drawbacks of the prior art. To this end, the invention relates to an aircraft propulsion system comprising a propeller having an axis of rotation, several electric motors, a transmission system configured to couple the electric motors to the propeller and comprising an output shaft connected to the propeller, as well as a propeller pitch adjustment system, the transmission system delimiting a front zone in which the propeller is positioned and a rear zone opposite the front zone, the propeller pitch adjustment system being positioned in the rear zone.

[0011] According to the invention, at least one of the electric motors is positioned in the forward zone. In addition, the propulsion assembly includes a connecting structure interposed between the propeller and the transmission system, the connecting structure and the output shaft of the transmission system connected to the propeller being configured so that no electric motor positioned in the forward zone interferes with the propeller.

[0012] Thus, the propeller pitch adjustment system, positioned at the rear of the transmission system, is no longer surrounded by electric motors, one of which is located in the forward area. This arrangement improves the accessibility of the propeller pitch adjustment system, particularly during maintenance.

[0013] According to another feature, the propulsion assembly includes a guidance system interposed between the connection structure and the output shaft of the transmission system connected to the propeller.

[0014] According to another feature, the connection structure includes a tube extending between first and second ends, the first end being connected to the transmission system.

[0015] According to another characteristic, the propulsion assembly includes at least one attachment structure configured to connect the propulsion assembly to an aircraft support structure, comprising at least one first attachment point positioned in a first plane and at least one second attachment point positioned in a second plane offset in a direction parallel to the axis of rotation relative to the first plane, the first and second attachment points being positioned on the transmission system and / or the connecting structure.

[0016] According to another characteristic, the first and second planes are positioned at the right of the connection structure, the first plane being located at the right of the first end of the tube, the second plane being located at the right of the second end of the tube.

[0017] According to another feature, the attachment structure comprises a frame positioned in a transverse plane, several oblique connecting rods having a first end connected by a first link to the frame and a second end connected by a second link to one of the second attachment points located at the second end of the tube of the connecting structure, and at least two transverse connecting rods, each connecting the frame to at least one first attachment point located at the first end of the tube of the connecting structure.

[0018] According to another characteristic, each oblique connecting rod has an orientation. In addition, for each oblique connecting rod, each of the first and second joints includes a pivot point positioned in a transverse plane and substantially perpendicular to the orientation of the corresponding oblique connecting rod.

[0019] According to another characteristic, the attachment structure includes: two transverse connecting rods positioned on either side of a vertical plane passing through the axis of rotation, for each transverse connecting rod, at least one first joint connecting the transverse connecting rod and the frame, as well as at least one second joint connecting the transverse connecting rod and the connecting structure, each of the first and second joints having a pivot axis substantially parallel to the axis of rotation.

[0020] According to another feature, the connection structure includes a plate, positioned at the first end of the tube, which has in a transverse plane an approximately triangular shape with rounded first, second and third vertices, the tube being positioned near the first vertex, the second and third vertices being connected by a side opposite the first vertex substantially horizontal, located above the tube and near the frame, the transverse connecting rods being connected to the plate at the level of the rounded second and third vertices.

[0021] The invention also relates to an aircraft comprising at least one propulsion system according to one of the preceding characteristics.

[0022] Other features and advantages will become apparent from the following description of the invention, given by way of example only, with reference to the accompanying drawings, among which: There figure 1 is a perspective view from an aircraft, The figure 2 is a schematic side view of an electric propulsion system illustrating one embodiment of art, The figure 3 is a schematic rear view of the electric propulsion assembly visible on the figure 2 , There figure 4 is a schematic side view of an electric propulsion assembly illustrating a first embodiment of the invention, The figure 5 is a schematic side view of an electric propulsion assembly illustrating a second embodiment of the invention, The figure 6 is a schematic side view of part of an electric propulsion assembly and its attachment structure illustrating one embodiment of the invention, The figure 7 is a schematic top view of the part of the electric propulsion assembly visible on the figure 6 , There figure 8 is a schematic front view of the part of the electric propulsion assembly visible on the figure 6 , There figure 9 is a front view of a plate of a connection structure illustrating one embodiment of the invention, The figure 10 is a side view of a connecting structure illustrating a first embodiment of the invention, The figure 11 is a side view of part of a connecting structure illustrating a second embodiment, and The figure 12 is a schematic side view of part of an electric propulsion assembly and its attachment structure illustrating another embodiment of the invention.

[0023] According to embodiments visible on the figures 4 et 5 An electric propulsion assembly 30 comprises a propeller 32 which has a rotation axis A32, several electric motors 34, a transmission system 36, such as a gearbox for example, configured to couple the electric motors 34 to the propeller 32, and a propeller pitch control system 38. Depending on an application, at least one such propulsion assembly 30 is intended to equip an aircraft.

[0024] The transmission system 36 defines a front zone, positioned at the front of the transmission system 36, in which the propeller 32 is located, and a rear zone, opposite the front zone, positioned at the rear of the transmission system 36. In one embodiment, the transmission system 36 comprises a housing 40 having a first transverse surface 40.1, oriented towards the front zone, and a second transverse surface 40.2, oriented towards the rear zone. The transmission system 36 also includes a hollow output shaft 42 connected to the propeller 32, projecting from the first transverse surface 40.1.

[0025] Each electric motor 34 includes an output shaft 34.1 connected to the transmission system 36.

[0026] The propeller pitch adjustment system 38 is positioned in the rear area on the second transverse surface 40.2 of the transmission system 36 and includes a control shaft 38.1 connected to the propeller 32, passing through the transmission system 36 and housed in the output shaft 42 of the transmission system 36.

[0027] The propeller pitch adjustment system 38 is connected by any suitable means to the transmission system 36. It is not described further as it may be identical to those of the prior art.

[0028] At least one of the electric motors 34 is positioned between the transmission system 36 and the propeller 32. According to this arrangement, each electric motor 34, positioned in the front zone, is fixed on the first transverse surface 40.1 of the transmission system 36. In addition, this first transverse surface 40.1 has a through hole for the output shaft 42 of the transmission system 36 as well as a through hole for the output shaft 34.1 of each electric motor 34 positioned in the front zone.

[0029] According to an embodiment visible on the figure 4 at least one electric motor 34 is positioned in the front area and at least one electric motor 34' is positioned in the rear area.

[0030] According to an embodiment visible on the figure 5 All the electric motors 34 are positioned in the forward zone. Only the propeller pitch adjustment system 38 is positioned on the second transverse surface 40.2 of the transmission system 36, in the rear zone. According to a first arrangement visible on the figure 4 The electric motors 34 positioned in the front zone are offset relative to the electric motor(s) 34' positioned in the rear zone. According to a second arrangement, the propulsion assembly 30 includes an electric motor located in the rear zone with an output shaft 34.1 aligned with the output shaft 34.1 of an electric motor 34 located in the front zone. This arrangement simplifies the architecture of the transmission system 36 by sharing certain elements of the transmission system 36 between the two electric motors arranged opposite each other on either side of the transmission system 36.

[0031] Regardless of the embodiment, the propeller pitch adjustment system 38 is not surrounded by electric motors, resulting in better accessibility.

[0032] The propulsion assembly 30 includes a connection structure 44 positioned in the forward area and interposed between the propeller 32 and the transmission system 36. According to one configuration, the electric propulsion assembly includes a guidance system 46 interposed between the connection structure 44 and the output shaft 42 of the transmission system 36 connected to the propeller 20.

[0033] The connecting structure 44 and the output shaft 42 of the transmission system 36 each have a length (dimension measured parallel to the longitudinal direction) such that no electric motor 34 positioned in the front area interferes with the propeller 32.

[0034] In one embodiment, the connection structure 44 is hollow and comprises a tube 48 extending between first and second ends 48.1, 48.2, the first end 48.1 of the tube 48 being connected by fastening elements to the housing 40 of the transmission system 36. In another configuration, the connection structure 44 comprises first and second flanges 50.1, 50.2 at the first and second ends of the tube 48, the first flange 50.1 connecting the tube 48 to the transmission system 36. Of course, the invention is not limited to this embodiment for the connection structure 44.

[0035] According to one embodiment, the guide system 46 comprises two bearings 52, 52' interposed between the tube 48 of the connecting structure 44 and the output shaft 42 of the transmission system 36 connected to the propeller 20, positioned near each of the ends 48.1, 48.2 of the tube 48. Of course, the invention is not limited to this embodiment for the guide system 46.

[0036] The propulsion assembly 30 includes at least one attachment structure 54 configured to connect the propulsion assembly 30 to an aircraft support structure, such as a wing structure for example.

[0037] The attachment structure 54 includes at least one first fixing point 56 positioned in a first plane P1 and at least one second fixing point 58 positioned in a second plane P2 offset in the longitudinal direction relative to the first plane P1, the first and second fixing points 56, 58 being positioned on the transmission system 36 and / or the connection structure 44. For greater stability and better load transfer, the first and second planes P1, P2 are as far apart as possible.

[0038] According to a configuration visible on the figure 12 , the first plane P1 is positioned at the right of the transmission system 36. The second plane P2 is positioned at the right of the connection structure 44, in particular at the right of the second end of the tube 48.

[0039] According to a configuration visible on the figures 5 à 7 The first and second planes P1 and P2 are positioned directly above the connecting structure 44, with the first plane P1 located at the first end 48.1 of the tube 48, and the second plane P2 located at the second end 48.2 of the tube 48. According to this configuration, the forces generated by the propeller 32 and transmitted to the aircraft's support structure do not pass through the transmission system 36, which is a critical component with regard to fire risks. In this case, the transmission system 36, and more specifically its housing 40, are not structural.

[0040] According to one embodiment, the attachment structure 54 comprises a frame 60 positioned in a transverse plane, approximately at the right of the first end 48.1 of the tube 48 of the connection structure 44, several oblique connecting rods 62.1 to 62.4 having a first end connected by a first link 64 to the frame 60 and a second end connected by a second link 66 to one of the second fixing points 58 located at the level of the second end 48.2 of the tube 48 of the connection structure 44 and at least two transverse connecting rods 68 each connecting the frame 60 to at least one first fixing point 56 located at the level of the first end 48.1 of the tube 48 of the connection structure 44.

[0041] In one configuration, the oblique connecting rods 62.1 to 62.4 are regularly distributed around the connecting structure 44. According to an arrangement visible on the figures 6 et 7 , the attachment structure 54 comprises four oblique connecting rods 62.1 to 62.4 located approximately in a vertical plane passing through the axis of rotation A32 and in a horizontal plane passing through the axis of rotation A32.

[0042] For each oblique connecting rod 62.1 to 62.4, each of the first and second joints 64, 66 comprises a joint having a pivot axis A64, A66 positioned in a transverse plane and substantially perpendicular to the orientation of the corresponding oblique connecting rod 62.1 to 62.4 (the orientation corresponding to the direction passing through the first and second ends of the corresponding oblique connecting rod). According to an embodiment visible in the figures 8 And 10, for each second connection 66, the connection structure 44 includes a clevis attached to the outer surface of the tube 48 having two wings between which is positioned the second end of the oblique connecting rod 62.1 to 62.4. In addition, for each first connection 64, the frame 60 includes a clevis having two wings between which is positioned the first end of the oblique connecting rod 62.1 to 62.4.

[0043] According to a configuration visible on the figure 8 , the attachment structure 54 includes two transverse connecting rods 68, 68' positioned on either side of a vertical plane passing through the axis of rotation A32 and, for each transverse connecting rod 68, 68', at least one first articulation 70 connecting the transverse connecting rod 68, 68' and the frame 60, at least one second articulation 72 connecting the transverse connecting rod 68, 68' and the connection structure 44.

[0044] Each of the first and second articulations 70, 72 has a pivot axis substantially parallel to the rotation axis A32.

[0045] According to one embodiment, the connection structure 44 comprises a plate 74, positioned at the first end 48.1 of the tube 48 (in place of the first collar 50.1 or juxtaposed to it), which has in a transverse plane an approximately triangular shape with rounded vertices, the tube 48 being positioned near a first vertex 74.1, the second and third vertices 74.2, 74.3 being connected by a side opposite to the first vertex 74.1 substantially horizontal, located above the tube 48 and near the frame 60, the transverse connecting rods 68, 68' being connected to the plate 74 at the second and third rounded vertices 74.2, 74.3. This plate 74 has at least one through hole 76 for the output shaft 34.1 of each electric motor 34 positioned at the front of the transmission system 36.

[0046] According to one configuration, the attachment structure 54 includes a first transverse connecting rod 68 connected to the frame 60 by a single first joint 70 and to the connecting structure 44 by a single second joint 72, and a second transverse connecting rod 68' connected to the frame 60 by two first joints 70, 70' and to the connecting structure 44 by a single joint 72. According to this configuration, the plate 74 includes first and second extensions 78, at each of the second and third vertices 74.2, 74.3, a first extension for the second joint 72 of the first transverse connecting rod 68, and another for the second joint 72 of the second transverse connecting rod 68'.

[0047] Alternatively, the second transverse connecting rod 68' could be connected to the frame 60 by a single first joint 70 and to the connecting structure 44 by two second joints 72.

[0048] According to an embodiment visible on the figure 10 , at least one of the second joints 72 comprises a clevis integral with the connecting structure 44 which has two flanges between which a transverse connecting rod 68, 68' is positioned. According to another embodiment visible on the figure 11 at least one of the second joints 72 comprises a yoke integral with the corresponding transverse connecting rod 68, 68', which has two flanges between which the plate 74 is positioned. Alternatively, at least one transverse connecting rod 68, 68' comprises two parallel plates, slightly spaced and arranged on either side of the plate 74

[0049] Of course, the invention is not limited to this embodiment for the attachment structure 54. Thus, as illustrated in the figure 12, the transverse connecting rods 68, 68' linking the frame 60 and the housing 40 can be replaced by deformable connecting elements 80 of the "silent block" type for example.

Claims

1. Aircraft propulsion assembly comprising a propeller (32) having an axis of rotation (A32), a plurality of electric motors (34), a transmission system (36) configured to couple the electric motors (34) to the propeller (32) and comprising an output shaft (42) connected to the propeller (32), and a propeller pitch adjustment system (38), the transmission system (36) delimiting a front zone in which the propeller (32) is positioned, and a rear zone opposite the front zone, the propeller pitch adjustment system (38) being positioned in the rear zone, characterized in that at least one of the electric motors (34) is positioned in the front zone, and in that the propulsion assembly comprises a connection structure (44) interposed between the propeller (32) and the transmission system (36), the connection structure (44) and the output shaft (42) of the transmission system (36) connected to the propeller (32) being configured in such a way that no electric motor (34) positioned in the front zone interferes with the propeller (32).

2. Propulsion assembly as claimed in claim 1, wherein the propulsion assembly comprises a guide system (46) interposed between the connection structure (44) and the output shaft (42) of the transmission system (36) connected to the propeller (20).

3. Propulsion assembly as claimed in one of the preceding claims, wherein the connection structure (44) comprises a tube (48) extending between first and second ends (48.1, 48.2), the first end (48.1) being connected to the transmission system (36).

4. Propulsion assembly as claimed in one of the preceding claims, wherein the propulsion assembly comprises at least one attachment structure (54) configured to connect the propulsion assembly to a support structure of an aircraft, comprising at least one first attachment point (56) positioned in a first plane (P1) and at least one second attachment point (58) positioned in a second plane (P2) offset from the first plane (P1) in a direction parallel to the axis of rotation (A32), the first and second attachment points (56, 58) being positioned on the transmission system (36) and / or the connection structure (44).

5. Propulsion assembly as claimed in claims 3 and 4, wherein the first and second planes (P1, P2) are positioned in line with the connection structure (44), the first plane (P1) being located in line with the first end (48.1) of the tube (48), the second plane (P2) being located in line with the second end (48.2) of the tube (48).

6. Propulsion assembly as claimed in the preceding claim, wherein the attachment structure (54) comprises a frame (60) positioned in a transverse plane, a plurality of oblique connecting rods (62.1 to 62.4) having a first end connected by a first link (64) to the frame (60) and a second end connected by a second link (66) to one of the second attachment points (58) located at the second end (48.2) of the tube (48) of the connection structure (44), and at least two transverse connecting rods (68) each connecting the frame (60) to at least one first attachment point (56) located at the first end (48.1) of the tube (48) of the connection structure (44).

7. Propulsion assembly as claimed in the preceding claim, wherein each oblique connecting rod (62.1 to 62.4) has an orientation, and in that, for each oblique connecting rod (62.1 to 62.4), each of the first and second links (64, 66) comprises a joint having a pivot axis (A64, A66) positioned in a transverse plane and substantially perpendicular to the orientation of the corresponding oblique connecting rod (62.1 to 62.4).

8. Propulsion assembly as claimed in one of claims 6 to 7, wherein the attachment structure (54) comprises : - two transverse connecting rods (68, 68') positioned on either side of a vertical plane passing through the axis of rotation (A32), - for each transverse connecting rod (68, 68'), at least one first joint (70) connecting the transverse connecting rod (68, 68') and the frame (60), and at least one second joint (72) connecting the transverse connecting rod (68, 68') and the connection structure (44), - each of the first and second joints (70, 72) having a pivot axis substantially parallel to the axis of rotation (A32).

9. Propulsion assembly as claimed in one of claims 6 to 8, wherein the connection structure (44) comprises a plate (74), positioned at the first end (48.1) of the tube (48), which plate has, in a transverse plane, an approximately triangular shape with first, second and third rounded vertices, the tube (48) being positioned close to the first vertex (74.1), the second and third vertices (74.2, 74.3) being connected by a side opposite the first substantially horizontal vertex (74.1), located above the tube (48) and close to the frame (60), the transverse connecting rods (68, 68') being connected to the plate (74) at the second and third rounded vertices (74.2, 74.3).

10. Aircraft comprising at least one propulsion assembly as claimed in one of the preceding claims.