Joint arrangement, drive system for driving control surfaces of an aircraft and aircraft with such a drive system
09701396 ยท 2017-07-11
Assignee
Inventors
Cpc classification
F16D3/2233
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/24
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D2003/22303
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/224
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y10S464/906
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
F16D3/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/2233
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/224
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D3/24
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A joint arrangement includes an outer joint component, an inner joint component, a cage and at least two balls located between the outer and inner joint component and in openings of the cage. The balls run in ball recesses, while at least two are in a mechanical contact with pressing devices, which are adapted for holding the respective balls in a radially flexible position relative to one of the inner joint component, the outer joint component and the cage and for pressing the respective balls into the corresponding recesses.
Claims
1. A joint arrangement comprising: an outer joint component having a spherical inner surface surrounding a hollow space and a first interface section, the inner surface comprising at least first and second outer ball recesses; an inner joint component positioned inside the hollow space of the outer joint component, the inner joint component having a spherical outer surface and a second interface section, the outer surface comprising at least first and second inner ball recesses; a spherical cage arranged in the hollow space between the inner surface of the outer joint component and the outer surface of the inner joint component, the cage comprising at least first and second openings extending from a side facing the outer joint component to a side facing the inner joint component; at least first and second balls; and at least first and second pressing devices, wherein the at least first and second balls are arranged in the first and second outer ball recesses, the first and second inner ball recesses and the first and second openings, respectively, of the cage for transferring a torque from the first interface section to the second interface section, wherein the at least first and second pressing devices are arranged in one of the inner joint component, the outer joint component and the cage, each in mechanical contact with one of the at least first and second balls, wherein the at least first and second pressing devices are adapted for holding the at least first and second balls in a respective recess with a predetermined maximum pressing force for limiting a maximum transferable torque of the joint arrangement.
2. The joint arrangement of claim 1, wherein each of the outer ball recesses constitutes a ball recess pair with an inner ball recess and corresponds to an opening in the cage, and wherein at least first and second first balls are arranged in the ball recess pairs and a corresponding opening of the cage.
3. The joint arrangement of claim 1, wherein the outer ball recesses comprise outer ball grooves comprising a radius of curvature exceeding the radius of curvature of the respective balls arranged therein, and wherein the center of curvature of the outer ball grooves is distanced from a geometrical center of the outer joint component.
4. The joint arrangement of claim 3, wherein the radius of curvature of the ball grooves are at least twice the radius of curvature of the respective balls arranged therein.
5. The joint arrangement of claim 1, wherein the outer ball recesses comprise outer ball grooves comprising a radius of curvature equaling the radius of curvature of the respective balls arranged therein, and wherein a central angle () of a cross-section of the inner ball recess exceeds a central angle () of a cross-section of the outer ball recess.
6. The joint arrangement of claim 1, wherein the pressing devices are arranged in the cage and support the respective balls in a radially flexible position relative to the cage, and wherein the cage comprises an inner cage surface having at least first and second rotatably supported second balls, and wherein the at least first and second second balls are arranged in corresponding inner recesses.
7. The joint arrangement of claim 1, wherein the cage is at least partially divided in a radial direction into a first cage part and a second cage part, wherein the second cage part surrounds the first cage part at least partially, each of the first and second cage part having at least first and second cage part recesses arranged in corresponding positions, wherein the pressing devices are arranged in one of the first cage part and the second cage part and support the at least first and second first balls in a radially flexible position relative to one of the first cage part and the second cage part, wherein the cage comprises an inner cage surface having at least first and second rotatably supported second balls and wherein the at least first and second second balls are arranged in corresponding inner recesses of the inner joint component, and wherein the cage comprises an outer cage surface having at least first and second rotatably supported third balls and wherein the at least first and second third balls are arranged in corresponding outer ball recesses of the outer joint component.
8. The joint arrangement of claim 1, wherein the pressing devices comprise springs arranged in pressing device recesses, and wherein each spring is mechanically coupled with an end face of the pressing device recess and the respective ball.
9. The joint arrangement of claim 1, wherein each first ball is supported on a ball cup.
10. The joint arrangement of claim 1, wherein at least two of the outer joint component, the inner joint component and the cage are adapted to constitute an electric generator.
11. The joint arrangement of claim 1, wherein the at least first and second pressing devices provide a radially flexible position support to the at least first and second balls, respectively.
12. The joint arrangement of claim 1, wherein, if a predetermined maximum shearing force between the outer joint component and the inner joint component is exceeded, at least one of the first and second balls is configured to move radially and leave the corresponding outer ball recess.
13. A drive system for control surfaces of an aircraft, comprising: a power control unit; at least one transmission shaft having a plurality of transmission shaft sections; and at least one drive station, wherein the transmission shaft sections are coupled by a joint arrangement comprising: an outer joint component having a spherical inner surface surrounding a hollow space and a first interface section, the inner surface comprising at least first and second outer ball recesses; an inner joint component positioned inside the hollow space of the outer joint component, the inner joint component having a spherical outer surface and a second interface section, the outer surface comprising at least first and second inner ball recesses; a spherical cage arranged in the hollow space between the inner surface of the outer joint component and the outer surface of the inner joint component, the cage comprising at least first and second openings extending from a side facing the outer joint component to a side facing the inner joint component; at least first and second balls; and at least first and second pressing devices, wherein the at least first and second balls are arranged in the first and second outer ball recesses, the first and second inner ball recesses and the first and second openings, respectively, of the cage for transferring a torque from the first interface section to the second interface section, wherein the at least first and second pressing devices are arranged in one of the inner joint component, the outer joint component and the cage, each in mechanical contact with one of the at least first and second balls, wherein the at least first and second pressing devices are adapted for holding the at least first and second balls in a respective recess with a predetermined maximum pressing force for limiting a maximum transferable torque of the joint arrangement.
14. An aircraft comprising: a drive system comprising: a power control unit; at least one transmission shaft having a plurality of transmission shaft sections; and at least one drive station, wherein the transmission shaft sections are coupled by a joint arrangement comprising: an outer joint component having a spherical inner surface surrounding a hollow space and a first interface section, the inner surface comprising at least first and second outer ball recesses; an inner joint component positioned inside the hollow space of the outer joint component, the inner joint component having a spherical outer surface and a second interface section, the outer surface comprising at least first and second inner ball recesses; a spherical cage arranged in the hollow space between the inner surface of the outer joint component and the outer surface of the inner joint component, the cage comprising at least first and second openings extending from a side facing the outer joint component to a side facing the inner joint component; at least first and second balls; and at least first and second pressing devices, wherein the at least first and second balls are arranged in the first and second outer ball recesses, the first and second inner ball recesses and the first and second openings, respectively, of the cage for transferring a torque from the first interface section to the second interface section, wherein the at least first and second pressing devices are arranged in one of the inner joint component, the outer joint component and the cage, each in mechanical contact with one of the at least first and second balls, wherein the at least first and second pressing devices are adapted for holding the at least first and second balls in a respective recess with a predetermined maximum pressing force for limiting a maximum transferable torque of the joint arrangement.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further characteristics, advantages and application options of the present invention are disclosed in the following description of the exemplary embodiments in the figures. All the described and/or illustrated characteristics per se and in any combination form the subject of the invention, even irrespective of their composition in the individual claims or their interrelationships. Furthermore, identical or similar components in the figures have the same reference characters.
(2)
(3)
(4)
(5)
(6)
(7)
DETAILED DESCRIPTION
(8)
(9) The cage 8 comprises openings 14 that are adapted for guiding the first balls 10 between the inner joint component 6 and the outer joint component 4. Exemplarily, the pressing devices 12 are arranged at the inner joint component 6 and comprise a recess 16 into which recess 16, e.g. a bushing, ball cups 18 may be moved. The crescent-shaped ball cups 18 are guided by means of linear guides 20 located at the side faces of the recess 16 and comprise an inner ball recess 19. The first balls 10 contact the inner ball recesses 19 by means of a circular contact line. The guides 20 run parallel to a sectional plane marked as AA and vertically to a sectional plane marked BB. The outward motion of the ball cups 18 may be limited by end stops 31 engaging correspondingly shaped steps of the ball cups 18. Between an underside of the ball cups 18 and the interior end face of the recess 16, springs 22 are located. By a force acting upon the first balls 10 into the direction of the recess 16, the ball cups 18 move inwardly, i.e. into the direction of a central axis 24. The inner ball recess 19 is a meridional groove, in which the first balls 10 may roll, clearly visible in
(10) The joint arrangement 2 is designed for transferring torque between the inner joint component 6 and the outer joint component 4. For the sake of clarifying the general setup the inner joint component 6 and the outer joint component 4 are arranged parallel to each other in the drawing of
(11) If this is the case, the pressing force upon the first balls 10 is insufficient to maintain their position in the outer recesses, such that the first balls 10 are moving in a radial direction onto an inner surface 29 of the outer joint component located between the outer recesses 28, which inner surface 29 does not allow the transfer of a shearing force, which leads to the interruption of the transfer of torque. The inner surfaces 29 separate the outer recesses 28 from each other and comprise a smaller distance to the central axis 24 than the outer recesses 28. To prevent the loss of the ball cups 18, the pressing devices 12 include end stops 30 that are adapted to hold the ball cups 18 in an outermost position. As the transition between the outer recesses 28 and the inner surfaces 29 may be smooth, the first balls 10 may conduct a slight lateral motion in the outer recesses 28, which may slightly damp harsh changes in the torque to be transferred.
(12) The outer ball recesses 28 comprise a radius of curvature which clearly exceeds the radius of curvature of the first balls 10, but which may be lower than the radius of curvature of the inner surfaces 29 between the outer ball recesses 28 in a circumferential direction. Furthermore, the center of curvature of the outer ball recesses 28 is located in a distance to the central axis 24. For example, the center of curvature may be positioned between the central axis 24 and the corresponding end face of the ball cup 18. Exemplarily, four centres 30a-30d of curvature of the outer recesses 28 are indicated in
(13)
(14) In
(15) On introduction of a torque through one of the interface sections 32 or 33 into the inner joint component 6 or outer joint component 4, the first balls 10 transfer a shearing force through the inner recess 19 and the outer recess 28, while conducting a balancing motion along the inner recess 19 and the outer recess 28 while the cage 8 maintains the relative positions of the first balls 10. End stops 88 limit the radial motion of the cage 8 in the direction of an angle between the axes 24 and 25 in the drawing plane of
(16) The basic design and setup of the joint arrangement according to
(17)
(18) A central angle of a cross-section of the inner ball recesses 40 is less than a central angle of a cross-section of the inner ball recesses 41 for maintaining a simultaneous rolling motion of the first balls 10 once the predetermined maximum torque is exceeded. An angle exceeding 90 prevents the first balls 10 from leaving the ball cups 18. As the pressing force onto the first balls 10 depends on an alignment angle the necessary central angle depends on the angle as well and may be calculated by the previously mentioned equation:
(19)
wherein
(20) T: torsional moment of a drive shaft,
(21) n.sub.k: number of first balls 10,
(22) r.sub.06 cos(/2): distance between a joint centre 0 and centres 6 of first balls 10,
(23) F.sub.S cos(/2): preload force of ball cup 18,
(24) : angle between the central axes of the joint components, bordered by body stops 88.
(25) Hence, the relationship between the torque limit and the preload force of the ball cups 18 depends on the alignment angle . The drive shaft mentioned above may be a shaft which is introduced into the second interface section 32.
(26) As rendered clear by
r.sub.67(1cos ()).
(27) The distance r.sub.029 between the joint centre 0 and the surface 29 of the first balls 10 at a cage position /2 follows to
r.sub.029=r.sub.06+r.sub.67 cos (()).
(28) The surface 29 is not part of a spherical shape.
(29)
(30) By placing the pressing devices 54 inside the cage 48, the pressing devices 54 directly act upon the first balls 10 such that the necessary preload force for maintaining a predetermined torque limit is completely independent from the alignment angle between the first joint component 44 and the second joint component 46.
(31) The central angle of the cross-section of the outer ball recesses 52 may therefore be calculated by the previously mentioned equation, in which the force F.sub.s does not need to be divided into separate force fractions for different directions, according to following equation:
(32)
wherein
(33) T: torsional moment of the drive shaft,
(34) n.sub.k: number of first balls 10,
(35) r.sub.06 cos(/2): distance between the joint centre 0 and centres 6 of first balls 10,
(36) F.sub.s: preload force of the ball cup 50,
(37) : angle between drive shaft and driven shaft, bordered by the body stop 88.
(38) The edge between an inner surface 29 of the outer joint component 44 and the outer recess 52 is labelled as 7. To maintain a simultaneous initiation of motion of the first balls 10 in case of overload, the depth of the outer recess 52 at a cage position /2 follows to:
r.sub.67(1cos ()).
(39) The distance r.sub.029 between the joint centre 0 and the inner surface 29 at a cage position /2 follows to:
r.sub.029=r.sub.06+r.sub.67 cos (()).
(40) The inner surface 29 is not part of a spherical shape.
(41) For coupling the cage 48 with the inner joint component 46, second balls 58 are provided that sit in the cage 48 and extend into inner ball recesses 60 located on the inner joint component 46. Consequently, when a predetermined maximum torque is exceeded, the first balls 10 and the ball cups 50 are pressed towards the central axis 24 under compression of the pressing devices 54 such that the cage 48 may freely rotate relative to the outer joint component 44. The recess 51 of the ball cup 50 for the first balls 10 has a spherical shape, the ball cup 50 has a cylindrical form, the ball cup sits in a cylindrical recess 36. An angle exceeding 90 prevents the first balls 10 from leaving their ball cups.
(42) In
(43) In analogy, the outer ball recesses 52 extend over a circular segment over exemplarily approximately 70 of the inner surface of the outer joint component 44. Since the pressing force is applied directly within the cage 48 onto the first balls 10, the alignment of the central axis 24 of the inner joint component 46 and a central axis 25 of the outer joint component 44 is not relevant for the pressing force onto the first balls 10.
(44)
(45) Additionally, first balls 10 are arranged between the outer cage part 68 and the inner cage part 70 and reside in substantially cylindrical ball cups 74 that are slidably arranged in the inner cage part 70. The first balls 10 are in contact with a cage part recess 71 of the outer cage part 68. In the embodiment of
(46) Therefore in
(47) By means of the radial cams 236 the preload force acting upon the first balls 10 is adjusted due to the variable ground of the recess. With a rising angle the preload force is increased, since the lever 136 is pushed to increase the compression of the springs 22 by a rising local height s of the cams.
(48) With a preload F.sub.s=c.sub.s s() the form of the radial cam is defined over
(49)
wherein
(50) T: torsional moment of the drive shaft,
(51) n.sub.k: number of first balls 10,
(52) r.sub.06 cos(/2): distance between joint centre 0 and centres 6 of first balls 10,
(53) c.sub.s: spring constant of spring 22,
(54) s() height of the radial cam at a cage position /2
(55) : angle between drive shaft and driven shaft, bordered by body stops 88.
(56) The central angle of the cross-section of the cage part recesses 71 may therefore be calculated as in the previous exemplary embodiment, as the force F.sub.s directly acts upon the first balls 10 and independent from alignment angle .
(57) Hence, by exceeding a predetermined maximum torque, the inner cage part 70 and the outer cage part 68 start to rotate relative to each other as the first balls 10 are displaced in a radial direction towards the central axis 24, 25 and their intersection, respectively.
(58)
(59)
(60) In the embodiment of
(61) With the preload F.sub.s=c.sub.ss() the form of the radial cam is defined over
(62)
wherein
(63) T: torsional moment of the drive shaft,
(64) n.sub.k: number of balls,
(65) r.sub.06 cos(/2): distance between joint centre 0 and centre 6 of first balls 10,
(66) c.sub.s: spring constant of spring 22,
(67) s(): height of the radial cam at a cage position /2,
(68) : angle between drive shaft and driven shaft, bordered by body stops 88.
(69)
(70) The transmission shafts 98 and 100 each may comprise joint arrangements 2, 32, 42, 62, 162 and 82 for compensation alignment alterations in the wing, which may also be effected by wing flexing. Due to the use of the joint arrangement 2, 32, 42, 62, 162 and 82 according to embodiments of the invention, the transferred torque is harmonic and the rotational speed does not accelerate or decelerate due to immanent characteristics of the joints. With a homokinetic joint 2, 32, 42, 62, 162 and 82 it is easier to change the wing sweepback over the wing span. Also a wing with a pivoting sweepback, comparable to the TORNADO or F14, may become simpler to design.
(71) In addition, it should be pointed out that comprising does not exclude other elements or steps, and a or an does not exclude a plural number. Furthermore, it should be pointed out that characteristics or steps which have been described with reference to one of the above exemplary embodiments can also be used in combination with other characteristics or steps of other exemplary embodiments described above. Reference characters in the claims are not to be interpreted as limitations.