Planetary gear mechanism

Abstract

To reduce the size of a lubrication structure in a planetary gear mechanism.SOLUTION: A planetary gear mechanism 32 has a case 41, a first shaft 63 having a connecting shaft 65, a second shaft 71 having a receiving hole 73 for rotatably receiving the connecting shaft, a sun gear 75 connected to the first shaft, a planetary carrier 76 connected to the second shaft, a plurality of planetary gears 77 supported to the planetary carrier, and a ring gear 91 arranged at an inner face of the case. A clearance 101 is formed between an upper face of the sun gear and a lower end face of the second shaft. A spiral groove 105 spirally extending in a vertical direction with the connecting shaft as a center, and connected to the clearance is formed at either of the connecting shaft and the receiving hole. A first lubricant path 108 for connecting the spiral groove and a slide contact part between the second shaft and the case is formed at the second shaft. A lubricant 110 is stored in the case. When the first shaft is rotated, at least a part of the plurality of planetary gears is immersed in the lubricant.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a planetary gear mechanism.

Background Art

[0002] Patent Document 1 discloses a planetary gear mechanism for an aircraft. The planetary gear mechanism has a tank for storing lubricating oil outside thereof, and an external pump that supplies the lubricating oil stored in the tank into the planetary gear mechanism via a duct. Further, the planet carrier of the planetary gear mechanism is provided with a plurality of internal pumps that feed lubricating oil to each part of the planetary gear mechanism. In each internal pump, a gear provided on its operating shaft meshes with a ring gear, and pumps lubricating oil by pressure through the rotation of the planet carrier.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] The above-described planetary gear mechanism has a plurality of pumps, and therefore has the problems of increased size and complicated structure.

[0005] In view of the above background, an object of the present invention is to reduce the size of a lubrication structure in a planetary gear mechanism.

Means for Solving the Problem

[0006] To solve the above problems, one aspect of the present invention is a planetary gear mechanism (32), comprising: a case (41); a first shaft (63) extending vertically and rotatably supported by the case, having a first connecting portion (64) at its lower end and a connecting shaft (65) at its upper end; a second shaft (71) coaxially with the first shaft and rotatably supported by the case, having a second connecting portion (72) at its upper end and a receiving hole (73) at its lower end for rotatably receiving the connecting shaft; a sun gear (75) coupled to the first shaft; a planetary carrier (76) coupled to the second shaft; and a plurality of planets rotatably supported by the planetary carrier and meshing with the sun gear. The sun gear has a gear (77) and a ring gear (91) provided on the inner surface of the case that meshes with a plurality of planetary gears, a gap (101) is formed between the upper surface of the sun gear and the lower end surface of the second shaft, a helical groove (105) is formed in one of the connecting shaft and the receiving hole, extending spirally up and down around the connecting shaft and connected to the gap, a first lubrication oil passage (108) is formed in the second shaft that connects the helical groove to the sliding contact portion of the second shaft and the case, lubricating oil (110) is stored inside the case, and when the first shaft is rotating, at least a portion of the plurality of planetary gears is immersed in the lubricating oil.

[0007] In this embodiment, when the first shaft rotates, the multiple planetary gears meshing with the sun gear rotate, and the lubricating oil adhering to the planetary gears is scattered radially outward from each planetary gear. As a result, the lubricating oil enters the gap between the upper surface of the sun gear and the lower end surface of the second shaft and reaches the lower end of the helical groove. Since the second shaft is decelerated relative to the first shaft at a predetermined reduction ratio, the connecting shaft rotates relative to the receiving hole. As a result, the connecting shaft, receiving hole, and helical groove function as a screw pump, sending the lubricating oil to the upper end of the connecting shaft. As a result, the lubricating oil passes through the first lubricating oil passage and is sent to the sliding contact area between the second shaft and the case. In this way, a pump for transporting lubricating oil is formed using the first and second shafts that constitute the input and output shafts of the planetary gear mechanism. Therefore, the lubrication structure in the planetary gear mechanism can be miniaturized.

[0008] In the above embodiment, the planetary carrier may be coupled to the outer circumferential surface of the lower end of the second axis.

[0009] In this embodiment, the lower surface of the planetary carrier can be used to guide lubricating oil into the gap between the upper surface of the sun gear and the lower end surface of the second shaft. This makes it easier to supply lubricating oil to the lower end of the helical groove.

[0010] In the above embodiment, a first bearing (86) is provided at the top of the case to rotatably support the second shaft, and the first lubrication passage may extend to the first bearing.

[0011] According to this embodiment, the first bearing can be lubricated.

[0012] In the above embodiment, a lubricating oil groove (102) may be formed on the inner circumference of the upper surface of the sun gear, recessed downward and extending in an annular shape to surround the connecting shaft, and facing the gap.

[0013] According to this embodiment, lubricating oil can be retained at the lower end of the connecting shaft, and lubricating oil can be easily supplied to the lower end of the helical groove.

[0014] In the above embodiment, a rotor shaft (15) is coaxially connected to the second connection portion of the second shaft, a support portion (14) that rotatably supports the rotor shaft is connected to the upper part of the case, and a second lubrication oil passage (109) connecting the helical groove and the sliding contact portion of the rotor shaft and the support portion may be formed in the second shaft and the rotor shaft.

[0015] According to this embodiment, the sliding contact portion between the rotor shaft and the support portion can be lubricated.

[0016] In the above embodiment, the support portion is provided with a second bearing (29) that rotatably supports the second shaft, and the second lubrication passage may extend to the second bearing.

[0017] According to this embodiment, the second bearing can be lubricated.

[0018] In the above aspect, an oil chamber (107) is formed between a bottom portion of the receiving hole and a tip end of the connection shaft, and the helical groove may be connected to the oil chamber.

[0019] According to this aspect, lubricating oil can be retained in the oil chamber.

[0020] In the above aspect, the second lubricating oil passage may be connected to the helical groove via the oil chamber.

[0021] According to this aspect, lubricating oil can be more reliably supplied to the second lubricating oil passage.

[0022] In the above aspect, a third bearing (96) that rotatably supports the rotor shaft is provided at an upper portion of the case, and the second bearing may be disposed above the third bearing.

[0023] According to this aspect, the lubricating oil supplied to the second bearing falls by gravity, and can lubricate the third bearing. Effects of the Invention

[0024] According to the above configuration, in a planetary gear mechanism, the lubrication structure can be reduced in size. Brief Description of the Drawings

[0025] [Figure 1] Perspective view of a rotary wing aircraft [Figure 2] Perspective view of a thrust generating device [Figure 3] Perspective view of a thrust generating device [Figure 4] Plan view of the thrust generating device with a rotary wing omitted [Figure 5] Vertical cross-sectional view of the thrust generating device [Figure 6] Vertical cross-sectional view showing an enlarged main part of the thrust generating device [Figure 7] Horizontal cross-sectional view of a speed reducer [Figure 8]Diagram illustrating the main components of a speed reducer. [Figure 9] A vertical cross-sectional view of the thrust generating device with the reduction gear and electric motor separated from the support section. [Modes for carrying out the invention]

[0026] The thrust generator and the planetary gear mechanism of the thrust generator according to the present invention will be described below with reference to the drawings. The thrust generator is used in rotary-wing aircraft, also known as electric multirotors.

[0027] As shown in Figure 1, the rotary-wing aircraft 1 has a body 2 extending forward and backward, a front wing 3 and a rear wing 4 extending from the body 2 to the left and right, and left and right arms 5 extending forward and backward and connected to the front wing 3 and the rear wing 4. The body 2 may be provided with a cabin for a crew member. A pair of rear thrust generators 7 that generate thrust in the forward and backward direction are provided at the rear end of the body 2. The front wing 3 and the rear wing 4 are preferably shaped to generate lift when moving forward.

[0028] Each arm 5 is equipped with multiple thrust generating devices 10. Each thrust generating device 10 generates thrust in the vertical direction. Each thrust generating device 10 is positioned on the arm 5 at intervals in the front-rear direction so as not to interfere with each other. Each arm 5 is equipped with multiple bases 11 to which the multiple thrust generating devices 10 are attached.

[0029] Each base 11 has a similar configuration. Similarly, each thrust generator 10 has a similar configuration. The following describes one thrust generator 10.

[0030] As shown in Figures 2 to 5, the base 11 is mounted on the arm 5 and has an upper surface 11A and a lower surface 11B. The upper surface 11A and the lower surface 11B are preferably horizontal. The base 11 has mounting holes 12 that penetrate in the vertical direction. The mounting holes 12 are open on the upper surface 11A and the lower surface 11B. The mounting holes 12 are preferably circular holes.

[0031] The thrust generating device 10 includes a support portion 14 detachably attached to the base 11, a rotor shaft 15 rotatably supported by the support portion 14, a plurality of rotor blades 16 coupled to the rotor shaft 15, and a drive unit 18 detachably attached to the support portion 14 or the base 11.

[0032] The support portion 14 has a cylindrical main body portion 21 that rotatably supports the rotor shaft 15, and a plurality of arm portions 22 that extend radially outward from the main body portion 21. The main body portion 21 is formed in a cylindrical shape that extends vertically. A bearing hole 23 that penetrates vertically is provided in the center of the main body portion 21. A flange portion 24 that expands radially outward is provided at the lower end of the main body portion 21.

[0033] Multiple arm portions 22 extend radially from the lower end of the main body portion 21. Each arm portion 22 may be connected to the main body portion 21 and the flange portion 24. Multiple arm portions 22 are detachably attached to the edge portion 25 of the mounting hole 12. The support portion 14 is detachably attached to the edge portion 25 of the mounting hole 12 by the multiple arm portions 22. In this embodiment, the upper surfaces 11A of the tips of the multiple arm portions 22 are fastened to the lower surface 11B of the base 11. In other embodiments, the lower surfaces 11B of the tips of the multiple arm portions 22 may be fastened to the upper surface 11A of the base 11. Each arm portion 22 and the base 11 may be detachably fastened to each other by fasteners 27 such as bolts and nuts.

[0034] When the support portion 14 is attached to the base 11, the main body portion 21 is positioned inside the mounting hole 12 when viewed from above. The main body portion 21 extends vertically through the mounting hole 12. The diameter of the main body portion 21 is smaller than the diameter of the mounting hole 12.

[0035] The rotor shaft 15 extends vertically and is rotatably supported in a bearing hole 23 via a bearing 29. The upper end of the rotor shaft 15 protrudes upward from the upper end of the main body 21. The rotor shaft 15 also extends upward from a mounting hole 12. Multiple rotor blades 16 are coupled to the upper end of the rotor shaft 15. Each rotor blade 16 extends radially from the rotor shaft 15. The bearing 29 may be located at the top of the bearing hole 23. In addition to the bearing 29, an additional bearing may be provided between the bearing hole 23 and the rotor shaft 15. The additional bearing may be located at the bottom of the bearing hole 23.

[0036] The drive unit 18 includes an electric motor 31 and a reduction gear 32 that reduces the driving force of the electric motor 31 and transmits it to the rotor shaft 15. The output shaft of the reduction gear 32 forms the output shaft of the drive unit 18. The output shaft of the drive unit 18 is detachably connected to the rotor shaft 15.

[0037] The reduction gear 32 is detachably mounted to the support 14 or the base 11. In this embodiment, the reduction gear 32 is detachably mounted to the support 14. The electric motor 31 is detachably mounted to the reduction gear 32. The output shaft of the electric motor 31 is detachably connected to the input shaft of the reduction gear 32. The electric motor 31, the reduction gear 32, and the rotor shaft 15 are arranged coaxially along axis A. The reduction gear 32 is mounted to the lower end of the support 14, and the electric motor 31 is mounted to the lower end of the reduction gear 32. The upper part of the drive unit 18 is composed of the reduction gear 32, and the lower part of the drive unit 18 is composed of the electric motor 31. The lower end of the drive unit 18 is located below the base 11.

[0038] The main body 21 of the support section 14 and the drive unit 18 are each positioned with a gap 34 between them and the edge 25 of the mounting hole 12. The gap 34 functions as an air passage. Air flowing downward from the multiple rotor blades 16 passes through the gap 34 and flows over the surface of the drive unit 18, cooling the drive unit 18.

[0039] The reduction gear 32 has a reduction gear case 41. The reduction gear case 41 is cylindrical and extends vertically. The reduction gear case 41 has a cylindrical peripheral wall 42 that extends vertically, an upper end wall 43 provided at the upper end of the peripheral wall 42, and a lower end wall 44 provided at the lower end of the peripheral wall 42. The upper end wall 43 of the reduction gear case 41 is detachably attached to the lower surface 11B of the flange portion 24 of the support portion 14. The support portion 14 and the reduction gear case 41 may be detachably fastened together by a plurality of bolts 46. For example, the bolts 46 may pass through bolt holes formed in the flange portion 24 and be screwed into female threaded holes formed on the upper end surface of the reduction gear case 41.

[0040] An upper bearing hole 51 is formed in the upper end wall 43 of the reduction gear case 41, penetrating vertically. A lower bearing hole 52 is formed in the lower end wall 44 of the reduction gear case 41, penetrating vertically. The upper bearing hole 51 and the lower bearing hole 52 are connected to the internal space 53 of the reduction gear case 41. The upper part of the upper bearing hole 51 is wider in diameter at a step compared to the lower part of the upper bearing hole 51.

[0041] The electric motor 31 has a cylindrical motor case 55. The motor case 55 extends in the vertical direction. The upper end surface of the motor case 55 is detachably attached to the lower end surface of the lower end wall 44 of the reduction gear case 41. The reduction gear case 41 and the motor case 55 are preferably detachably fastened together by a plurality of bolts. The outer diameter of the motor case 55 is preferably larger than the outer diameter of the reduction gear case 41. The lower end wall 44 of the reduction gear case 41 is preferably provided with a plurality of fastening flanges that project radially outward. Bolt holes are formed in each fastening flange that penetrate in the vertical direction, and female threaded holes are formed in the upper end surface of the motor case 55. The bolts pass through the bolt holes of the fastening flanges and are preferably detachably screwed into the female threaded holes of the motor case 55.

[0042] The motor output shaft 61, which is the output shaft of the electric motor 31, extends vertically and protrudes upward from the upper end surface of the motor case 55.

[0043] The gearbox 32 is a planetary gear mechanism. The gearbox 32 has a first shaft 63 that is rotatably supported in the gearbox case 41. The first shaft 63 extends vertically. The first shaft 63 has a first connecting portion 64 at its lower end and a connecting shaft 65 at its upper end. The first shaft 63 forms the input shaft of the gearbox 32. The first connecting portion 64 is rotatably supported in the lower bearing hole 52 of the gearbox case 41 via a bearing 66. It is preferable that an oil seal 67 be provided between the first connecting portion 64 of the first shaft 63 and the lower bearing hole 52.

[0044] The first connecting portion 64 is connected coaxially to the motor output shaft 61. The first shaft 63 and the motor output shaft 61 fit together and rotate as a single unit. For example, the first connecting portion 64 has a rectangular hole that is recessed in the axial direction, and the motor output shaft 61 has a rectangular prism portion that fits into the rectangular hole. The shape of the fitting portion between the motor output shaft 61 and the first shaft 63 only needs to be a structure that is detachably attached in the axial direction, and the motor output shaft 61 and the first shaft 63 may be fitted together by fitting with fine grooves extending in the axial direction, so-called spline fitting.

[0045] The gearbox 32 has a second shaft 71 rotatably supported in the gearbox case 41. The second shaft 71 is arranged coaxially with the first shaft 63. The second shaft 71 is positioned above the first shaft 63 and extends vertically. The second shaft 71 has a second connecting portion 72 at its upper end and a receiving hole 73 at its lower end for rotatably receiving a connecting shaft 65. The second shaft 71 forms the output shaft of the gearbox 32. The receiving hole 73 is recessed upward from the lower end surface 71A of the second shaft 71. The receiving hole 73 is a circular hole coaxial with the second shaft 71. The outer circumferential surface of the connecting shaft 65 and the inner circumferential surface of the receiving hole 73 are in sliding contact.

[0046] As shown in Figures 5, 7, and 8, a sun gear 75 is coupled to the first shaft 63. The sun gear 75 is preferably located directly below the connecting shaft 65. The sun gear 75 is a spur gear coaxial with the first shaft 63.

[0047] A planetary carrier 76 is coupled to the second shaft 71. Multiple planetary gears 77 are rotatably supported on the planetary carrier 76. Each planetary gear 77 is a spur gear. In this embodiment, the reducer 32 has three planetary gears 77. The planetary carrier 76 is coupled to the outer circumferential surface of the lower end of the second shaft 71.

[0048] The planetary carrier 76 has an annular first plate 81 connected to the lower end of the second shaft 71, a plurality of support shafts 82 extending downward from the first plate 81, a second plate 83 connected to the lower ends of the plurality of support shafts 82, and a cylindrical extension tube 84 extending downward from the second plate 83. The first plate 81 is formed in a flat plate shape facing up and down and extends radially outward from the outer circumference of the lower end of the second shaft 71. The plurality of support shafts 82 are arranged parallel to the second shaft 71 and are arranged at equal intervals in the circumferential direction around the second shaft 71. Each support shaft 82 is formed in a cylindrical shape. The second plate 83 is formed in a flat plate shape facing up and down. The second plate 83 is arranged parallel to the first plate 81 with a gap between them. A through hole 85 is formed in the center of the second plate 83, penetrating vertically.

[0049] A bearing 86 is provided at the top of the gearbox case 41 to rotatably support the second shaft 71. The bearing 86 is located below the upper bearing hole 51 and rotatably supports the lower part of the second shaft 71. The extension tube 84 is rotatably supported on the inner surface of the gearbox case 41 via a bearing 87.

[0050] The first shaft 63 extends vertically through the through-hole 85 of the second plate 83 and the inside of the extension tube 84. A bearing 89 is preferably provided between the first shaft 63 and the through-hole 85 of the second plate 83. The sun gear 75 is positioned between the first plate 81 and the second plate 83. The sun gear 75 meshes with each of the multiple planetary gears 77.

[0051] A ring gear 91 is provided on the inner surface of the reduction gear case 41. The ring gear 91 is an internal gear and is arranged coaxially with the sun gear 75 and the planetary gears 77. The ring gear 91 meshes with multiple planetary gears 77. The ring gear 91 is coupled to the inner surface of the peripheral wall 42.

[0052] The lower end of the rotor shaft 15 protrudes into the upper bearing hole 51 of the reduction gear case 41 and is detachably coupled to the upper end of the second shaft 71. A spline shaft portion 93 is provided on one of the rotor shaft 15 and the second shaft 71 (output shaft of the drive unit 18), and a spline hole 94 into which the spline shaft portion 93 fits is provided on the other of the rotor shaft 15 and the second shaft 71. In this embodiment, the spline shaft portion 93 is provided at the upper end of the second shaft 71 and the spline hole 94 is provided at the lower end of the rotor shaft 15. By fitting the spline shaft portion 93 into the spline hole 94, the rotor shaft 15 rotates integrally with the second shaft 71. The lower end of the rotor shaft 15 is rotatably supported on the upper part of the upper bearing hole 51 via a bearing 96.

[0053] The bearings 29 and 96 are preferably bearings capable of supporting radial and axial loads. The bearings 29 and 96 are preferably, for example, tapered roller bearings or angular contact ball bearings. The bearings 66, 86, 87, and 89 are preferably bearings capable of supporting radial loads. The bearings 66, 86, 87, and 89 are preferably, for example, ball bearings or sliding bearings.

[0054] As shown in Figure 6, a gap 101 is formed between the upper surface 75A of the sun gear 75 and the lower end surface 71A of the second shaft 71. The lower end surface 71A of the second shaft 71 is located on the same plane as the lower surface 81A of the first plate 81. Therefore, a gap 101 is also formed between the upper surface 75A of the sun gear 75 and the lower surface 81A of the first plate 81. A lubricating oil groove 102 is formed on the inner circumference of the upper surface 11A of the sun gear 75, recessed downwards and extending in an annular shape to surround the connecting shaft 65. The lubricating oil groove 102 is opposite the gap 101.

[0055] A helical groove 105 is formed in one of the connecting shaft 65 and the receiving hole 73, extending spirally up and down around the connecting shaft 65. The lower end of the helical groove 105 is connected to the gap 101. That is, the lower end of the helical groove 105 reaches the upper surface 11A of the sun gear 75. The lower end of the helical groove 105 may also be connected to the lubricating oil groove 102. The upper end of the helical groove 105 reaches the tip of the connecting shaft 65. An oil chamber 107 is formed between the tip of the connecting shaft 65 and the bottom of the receiving hole 73.

[0056] As shown in Figures 5 and 8, the second shaft 71 has a first lubrication oil passage 108 that extends from the helical groove 105 to the sliding contact area between the second shaft 71 and the reduction gear case 41. The first lubrication oil passage 108 may be connected to the helical groove 105 directly or via the oil chamber 107. In this embodiment, the first lubrication oil passage 108 extends linearly from the helical groove 105 to the bearing 86.

[0057] The second shaft 71 and the rotor shaft 15 have a second lubrication oil passage 109 that extends from the helical groove 105 to the sliding contact area between the rotor shaft 15 and the support portion 14. The second lubrication oil passage 109 may be connected to the helical groove 105 directly or via the oil chamber 107. In this embodiment, the second lubrication oil passage 109 extends linearly from the oil chamber 107 to the bearing 96.

[0058] Lubricating oil is stored inside the gearbox case 41. When the first shaft 63 is rotating, at least a portion of the multiple planetary gears 77 are immersed in the lubricating oil. As shown in Figure 5, the oil level 110 of the lubricating oil is positioned at the same height as the multiple planetary gears 77.

[0059] The lightning surge protection structure of the thrust generator 10 is described below. The skeletons and outer surfaces of the main body 2, forewings 3, rearwings 4, and arms 5 of the rotorcraft 1 are made of conductive metal. The metal may be, for example, iron or aluminum. The base 11, which forms part of the arm 5, is also made of conductive metal.

[0060] As shown in Figure 5, the rotor shaft 15, multiple rotor blades 16, and support portion 14 that constitute the thrust generator 10 are made of conductive metal. The support portion 14 is electrically attached to the base 11. Specifically, the support portion 14 is electrically in contact with the base 11 at multiple arm portions 22. As shown in Figure 3, the arm portions 22 are provided with ribs 111 that extend from the main body portion 21 to the tips of the arm portions 22. The ribs 111 increase the cross-sectional area of ​​the arm portions 22 and reduce the electrical resistance of the arm portions 22. The ribs 111 also function as reinforcing structures for the main body portion 21 and the arm portions 22. The height of the ribs 111 decreases toward the tip of the arm portion 22.

[0061] As shown in Figure 5, the rotor shaft 15 is electrically supported by the support portion 14. Specifically, a bearing 29 provided between the rotor shaft 15 and the support portion 14 is conductive, and the rotor shaft 15 is electrically connected to the support portion 14 via the bearing 29. In addition, the support portion 14 may be provided with a conductive brush 113 that slides against the outer circumferential surface of the rotor shaft 15.

[0062] The drive unit 18 is attached to the support unit 14 via a first electrical insulating portion 115. The first electrical insulating portion 115 may be an independent electrical insulating material interposed between the support unit 14 and the drive unit 18. Alternatively, the first electrical insulating portion 115 may be an electrical insulating coating formed on at least one surface of the support unit 14 and the drive unit 18.

[0063] The second shaft 71, which forms the output shaft of the drive unit 18, is connected to the rotor shaft 15 via a second electrical insulating portion 116. The second electrical insulating portion 116 may be an independent electrical insulating material interposed between the second shaft 71 and the rotor shaft 15. Alternatively, the second electrical insulating portion 116 may be an electrical insulating coating formed on at least one surface of the second shaft 71 and the rotor shaft 15.

[0064] The electrical insulating material may be made of, for example, ceramics or rubber. The electrical insulating coating may be a phosphate coating such as manganese phosphate or an anodized coating.

[0065] The first electrical insulating portion 115 may be, for example, an electrical insulating material interposed between the gearbox case 41 and the support portion 14. The first electrical insulating portion 115 may include a bush provided between the bolt 46 fastening the gearbox case 41 and the support portion 14 and the support portion 14. The bush is formed of an electrical insulating material and prevents the bolt 46 from contacting the support portion 14. Alternatively, the first electrical insulating portion 115 may be interposed between the gearbox case 41 and the bearing 96.

[0066] The first electrical insulating portion 115 may be an electrical insulating film formed on the contact portion between the reduction gear case 41 and the support portion 14, the contact portion between the reduction gear case 41 and the bearing 96, or the contact portion between the reduction gear case 41 and the bolt 46.

[0067] The second electrical insulation portion 116 is preferably an electrical insulating coating formed on at least one of the spline shaft portion 93 and the spline hole 94. This allows the rotor shaft 15 and the second shaft 71, which is the output shaft of the drive unit 18, to be connected in an electrically insulated state while suppressing an increase in size.

[0068] Since the multiple rotor blades 16 and rotor shafts 15 are positioned above the drive unit 18, the rotor blades 16 and rotor shafts 15 are more susceptible to lightning strikes than the drive unit 18. The first electrical insulation section 115 and the second electrical insulation section 116 cause lightning surges generated on the rotor blades 16 and rotor shafts 15 to flow more easily towards the base 11 than towards the drive unit 18, thus protecting the drive unit 18 from lightning surges. In addition, since the support section 14 and the drive unit 18 can be positioned close together, the size of the thrust generator 10 can be suppressed. Therefore, in the thrust generator 10, it is possible to suppress the flow of lightning surges to the drive unit 18 while suppressing an increase in size.

[0069] The ribs 111 increase the cross-sectional area of ​​the arm portion 22, thereby reducing the electrical resistance of the arm portion 22. This makes it easier for lightning surges to flow through the arm portion 22 to the base 11. The brushes 113 are electrically connected to the rotor shaft 15 and the support portion 14. This makes it easier for lightning surges to flow from the rotor shaft 15 to the support portion 14 rather than the second shaft 71.

[0070] The drive unit 18 and the second shaft 71 that constitutes the output shaft of the drive unit 18 are preferably made of a material with lower conductivity than the base 11. This makes it easier for lightning surges to flow from the rotor shaft 15 and support part 14 to the base 11 rather than to the drive unit 18 and the second shaft 71.

[0071] The operation and effects of the thrust generator 10 are described below. The driving force of the electric motor 31 is reduced by the reduction gear 32 and transmitted to the rotor shaft 15. As the rotor shaft 15, which has multiple rotor blades 16, rotates, the thrust generator 10 generates thrust in the vertical direction.

[0072] In the reduction gear 32, the rotation of the first shaft 63, which has a sun gear 75, causes the multiple planetary gears 77 to rotate, as does the rotation of the planetary carrier 76 and the second shaft 71 that support the multiple planetary gears 77. At this time, at least a portion of each planetary gear 77 is immersed in lubricating oil, so the lubricating oil adhering to each planetary gear 77 is scattered radially outward from each planetary gear 77. As a result, as shown in Figure 6, the lubricating oil enters the gap 101 between the upper surface 75A of the sun gear 75 and the lower end surface 71A of the second shaft 71 and reaches the lower end of the helical groove 105. Since the second shaft 71 is reduced relative to the first shaft 63 by a reduction ratio determined by the number of teeth of each gear, the connecting shaft 65 rotates relative to the receiving hole 73. As a result, the connecting shaft 65, the receiving hole 73, and the helical groove 105 function as a screw pump and send the lubricating oil to the upper end of the connecting shaft 65. As a result, the lubricating oil is delivered to the bearing 86 through the first lubricating oil passage 108 connected to the helical groove 105. This lubricates the bearing 86.

[0073] Furthermore, as shown in Figure 5, the lubricating oil in the helical groove 105 is supplied to the bearing 29 via the oil chamber 107 and the second lubricating oil passage 109. This lubricates the bearing 29. The lubricating oil supplied to the bearing 29 flows downward by gravity, passing through bearings 96 and 86 located below the bearing 29. This lubricates the bearing 96. The oil chamber 107 holds the lubricating oil. This ensures a more reliable supply of lubricating oil to the second lubricating oil passage 109.

[0074] The first plate 81 of the planetary carrier 76, located at the lower end of the second shaft 71, guides the lubricating oil scattered from each planetary gear 77 into the gap 101. This facilitates the supply of lubricating oil to the lower end of the helical groove 105. The lubricating oil groove 102 holds lubricating oil at the lower end of the connecting shaft 65. This also facilitates the supply of lubricating oil to the lower end of the helical groove 105.

[0075] As described above, a pump for transporting lubricating oil is formed using the first shaft 63 and the second shaft 71, which constitute the input shaft and output shaft of the planetary gear mechanism. Therefore, the lubrication structure in the reducer 32 can be miniaturized. The bearings 66, 87, and 89 are immersed in the lubricating oil and are lubricated.

[0076] As shown in Figure 9, in the thrust generator 10, the drive unit 18 can be removed from the support 14 and base 11 while the support 14 remains attached to the base 11. Therefore, when the drive unit 18 is removed from the support 14 and base 11, the rotor blades 16 and rotor shaft 15 do not need to be removed from the base 11. This improves the ease of maintenance of the drive unit 18 in the thrust generator 10 of the rotorcraft 1.

[0077] Furthermore, the electric motor 31 can be removed while the reduction gear 32 remains attached to the support section 14. The electric motor 31, reduction gear 32, and rotor shaft 15 are arranged coaxially. Therefore, the direction in which the reduction gear 32 and electric motor 31 are removed from the rotor shaft 15 and support section 14 is the same, making removal and installation easier.

[0078] Each bolt 46 for attaching the gearbox 32 to the support section 14 is positioned so as to overlap with the mounting hole 12 when viewed from above. Therefore, the worker can attach and detach the bolt 46 from above the mounting hole 12.

[0079] This concludes the description of specific embodiments, but the present invention is not limited to the above embodiments and can be broadly modified and implemented. For example, the bearing 86 may be supported by the main body portion 21 of the support portion 14. Also, each arm portion 22 of the support portion 14 may be coupled to the upper surface 11A of the base 11. In this case, the upper part of the reduction gear 32 may be placed inside the mounting hole 12. [Explanation of Symbols]

[0080] 1: Rotary-wing aircraft 10: Thrust Generator 11: Bass 12: Mounting holes 14: Support part 15: Rotor shaft 16: Rotary Wing 18: Drive Unit 21: Main body 22: Arm section 25: Edge 29, 66, 86, 87, 89, 96: Bearings 31: Electric motor 32:Reducer 34: Gap 41: Gear reducer case 42: Peripheral wall 43:Top end wall 44: Lower end wall 46: Bolt 61: Motor output shaft 63: 1st axis 64: First connection section 65: Connecting shaft 71: 2nd axis 71A: Bottom end surface 72: Second connection section 73: Receptor pore 75: Sangiya 75A:Top surface 76: Planetary Carrier 77: Planetary Gear 81A: Bottom surface 91: Ring gear 93: Spline shaft 94: Splined hole 101: Gap 102: Lubricating oil groove 105: Spiral groove 107: Oil room 108: 1st lubricating oil path 109:Second lubricating oil path 111: Rib 113: Brush 115: First electrical insulation section 116: Second Electrical Insulation Section

Claims

1. It is a planetary gear mechanism, The case and A first shaft extending vertically and rotatably supported in the case, having a first connecting portion at its lower end and a connecting shaft at its upper end, A second shaft is rotatably supported in the case coaxially with the first shaft, having a second connecting portion at its upper end and a receiving hole at its lower end for rotatably receiving the connecting shaft, A sun gear coupled to the first shaft, The planetary carrier coupled to the second axis, Multiple planetary gears are rotatably supported on the planetary carrier and mesh with the sun gear, The case has a ring gear provided on its inner surface that meshes with a plurality of planetary gears, A gap is formed between the upper surface of the sun gear and the lower end surface of the second shaft. A spiral groove is formed in either the connecting shaft or the receiving hole, extending spirally up and down around the connecting shaft and connected to the gap. The second shaft has a first lubrication passage that connects the helical groove and the sliding contact portion of the second shaft and the case. Lubricating oil is stored inside the aforementioned case. A planetary gear mechanism in which, when the first shaft is rotating, at least a portion of the multiple planetary gears are immersed in the lubricating oil.

2. The planetary gear mechanism according to claim 1, wherein the planetary carrier is coupled to the outer circumferential surface of the lower end of the second shaft.

3. A first bearing is provided at the top of the case to rotatably support the second shaft. The planetary gear mechanism according to claim 1, wherein the first lubrication passage extends to the first bearing.

4. The planetary gear mechanism according to claim 1, wherein the inner circumference of the upper surface of the sun gear is recessed downward and extends in an annular shape so as to surround the connecting shaft, and a lubricating oil groove is formed facing the gap.

5. The rotor shaft is coaxially connected to the second connection portion of the second shaft. A support portion for rotatably supporting the rotor shaft is attached to the upper part of the case. The planetary gear mechanism according to claim 1, wherein the second shaft and the rotor shaft have a second lubrication oil passage that connects the helical groove and the sliding contact portion of the rotor shaft and the support portion.

6. The support portion is provided with a second bearing that rotatably supports the second shaft. The planetary gear mechanism according to claim 5, wherein the second lubrication passage extends to the second bearing.

7. An oil chamber is formed between the bottom of the receiving hole and the tip of the connecting shaft. The planetary gear mechanism according to claim 6, wherein the helical groove is connected to the oil chamber.

8. The planetary gear mechanism according to claim 7, wherein the second lubrication passage is connected to the helical groove via the oil chamber.

9. A third bearing is provided at the top of the case to rotatably support the rotor shaft. The planetary gear mechanism according to any one of claims 6 to 8, wherein the second bearing is positioned above the third bearing.

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