Patent Application
20130276562
Many seat assemblies, such as vehicle seat assemblies, are adjustable in a variety of directions. For example, vehicle seat assemblies may translate in a generally horizontal front-to-back direction, may translate in a vertical direction, and/or may rotate about various axes to recline or otherwise adjust. Drive systems are thus included in the seat assemblies to facilitate these adjustments.
For example, to translate in a front-to-back direction, a seat assembly may include a frame having one or more movable tracks mounted in one or more fixed tracks. The movable tracks translate with respect to the fixed tracks. Further, one or more lead screws may be connected to the movable tracks. Rotation of the lead screws may drive the movable tracks, and thus the seat assembly.
Typically, worm gears are utilized to drive the lead screws. Rotation of components of the worm gears cause rotation of the lead screws. However, various issues have arisen related to the use of worm gears to drive vehicle seat assemblies. In particular, worm gears have relatively low load capacity, due to friction and high contact stresses during operation. Frequently, the loads exerted on seat assemblies by, for example, users sitting or lying on the seat assemblies exceed the low load capacities of the worm gears. This can lead to damage to or failure of the worm gears.
Attempts have been made to increase the load capacity of such worm gears by forming the worm gear components from exotic materials having higher load capacities. However, these materials are typically expensive, and this additional material expense is undesirably passed on to the consumer.
Accordingly, an improved seat assembly and drive system for a seat assembly are desired in the art. Particularly, seat assemblies and drive systems with high load capacities, and that utilize commonly available materials, would be advantageous.
In accordance with one embodiment of the present invention, a drive system for moving a support assembly is disclosed. The drive system includes a lead screw configured for connection to the support assembly and defining a longitudinal axis. The drive system further includes an epicyclic gear assembly. The epicyclic gear assembly includes a carrier and a plurality of rotatable gears. The epicyclic gear assembly is rotationally coupled to the lead screw. Operation of the epicyclic gear assembly causes translation of the support assembly along the longitudinal axis.
In accordance with another embodiment of the present invention, a seat assembly is disclosed. The seat assembly includes a support assembly configured to support a user, and a drive system connected to the support assembly and configured to move the support assembly. The drive system includes a lead screw attached to the support surface and defining a longitudinal axis. The drive system further includes an epicyclic gear assembly. The epicyclic gear assembly includes a carrier and a plurality of rotatable gears. The epicyclic gear assembly is rotationally coupled to the lead screw. Operation of the epicyclic gear assembly causes translation of the support assembly along the longitudinal axis.
Other features and aspects of the present invention are set forth in greater detail below.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.
It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention.
Generally speaking, the present disclosure is directed to drive systems for seat assemblies. The drive systems include epicyclic gear assemblies coupled to lead screws. The epicyclic gear assemblies are rotationally coupled to the lead screws, and operation thereof moves the seat assemblies. Epicyclic gear assemblies advantageously allow for load sharing between the various gears thereof, and thus have higher power densities and higher load capacities than, for example, worm gears. Thus, the present inventors have discovered that epicyclic gear assemblies as disclosed herein are particularly suited to drive seat assemblies. Further, drive systems and seat assemblies including epicyclic gear assemblies may be formed from commonly available materials, and are thus inexpensive while providing advantageous loading qualities.
As further illustrated in
A support assembly 12 according to the present disclosure may be movable in a variety of directions. In particular, a support assembly 12 may be translatable in a generally horizontal front-to-back direction 20, a generally horizontal side-to-side direction, or a vertical direction. For example, a frame 16 according to the present disclosure may include movable components that may cause movement of the support assembly 12.
One embodiment of the various movable component of a frame 16 is shown in
In some embodiments, a frame 16 according to the present disclosure may further include one or more cross-beams 36. The cross-beams 36 may extend generally transversely to the tracks 30, and may, for example, extend between two spaced apart generally parallel tracks 30 as shown. A cross-beam 36 may be connected to the fixed portion 32 or to the movable portion 34 of a track 30, and thus itself be fixed or movable. A cross-beam 36 may be connected to a support surface 14 in addition to or alternatively to movable portions 34 as discussed above.
A seat assembly 10 according to the present disclosure may further include one or more drive systems 50, as shown in
A drive system 50 according to the present disclosure may further include one or more epicyclic gear assemblies 56, as shown in
Any suitable epicyclic gear assembly 56 may be utilized in accordance with the present disclosure. For example, in exemplary embodiments, the epicyclic gear assembly 56 may be a planetary gear assembly. Alternatively, however, the epicylic gear assembly may be a star gear assembly, a solar gear assembly, or any other suitable epicyclic gear assembly. Still further, it should be understood that while the present disclosure describes various embodiments of single stage epicyclic gear assemblies, multiple stage epicyclic gear assemblies, epicyclic gear assemblies with differentials, and any other suitable varieties of epicyclic gear assemblies are within the scope and spirit of the present disclosure.
As shown in
In some embodiments, as shown, a rod 58 may couple various epicyclic gear assemblies 56 together. The rod 58 may maintain alignment of the epicyclic gear assemblies 56 with respect to each other during operation.
An epicyclic gear assembly 56 according to the present disclosure may include a gearbox 60, as shown in
In exemplary embodiments, as shown in
In some embodiments as shown in
The carrier 62 may include a plurality of threads 76, as shown in
Further, a carrier 62 according to the present disclosure may include, for example, an outer portion 82 and an inner nut portion 84, as shown in
It should be understood that the present disclosure is not limited to embodiments wherein the lead screw 52 extends through the carrier 62. For example, in other embodiments, the threads 76 or splines 77 may be defined on an outer surface 86 of the carrier 62, and the lead screw 52 and carrier 62 may be arranged such that the threads 72 and threads 76 or splines 75 and splines 77 thus mesh. In some of these embodiments, the carrier may include the nut portion as an outer portion relative to an inner portion, such that the nut portion defines the outer surface 86. Still further, the present disclosure is not limited to embodiments wherein the carrier 62 is coupled to the lead screw 52. For example, in other embodiments, any other suitable gear or component of the epicyclic gear assembly 56 may be coupled to the lead screw 52.
As discussed, the epicyclic gear assembly 56 may further include a plurality of rotatable gears. For example, the epicyclic gear assembly 56 may include a sun gear 100 and one or more planet gears 102, as well as a drive gear 104. Each of these gears may rotate about an individual axis. For example, the sun gear 100 may rotate about a central sun axis 110, each planet gear 102 may rotate about a central planet axis 112, and the drive gear may rotate about a central drive axis 114. Further, various of the rotatable gears may rotate about the axes of other gears. For example, as shown in
Each gear of an epicyclic gear assembly 56 according to the present disclosure may include a plurality of teeth defined on an outer surface thereof. The teeth may be sized and shaped to mesh together such that rotation of various of the gears may drive or be driven by rotation of other various gears.
Any suitable number of planet gears 102 may be utilized in an epicyclic gear assembly 56 of the present disclosure. For example, in some embodiments, between three and nine planet gears 102 may be utilized. In other embodiments, however, less than three or more than nine planet gears 102 may be utilized. Notably, the load capacity of a drive system 50 can be scaled through the use of different numbers of planet gears 102. Further, size of the drive system 50 can be scaled through the use of different numbers of planet gears 102. Thus, in various embodiments, various different numbers of planet gears may be utilized for various applications. The drive gear 104 may be separate from the planet gears 102, as shown, or alternatively the drive gear 104 may be one of the planet gears 102.
As shown in
The sun gear 100 may in exemplary embodiments further define a central opening 120. The central opening 120 may extend through the sun gear 100 along the central sun axis 110. Further, the central sun axis 110 may be collinear with the longitudinal axis 54. The lead screw 52 may thus extend through the sun gear 100. Further, the central sun axis 110 and the central carrier axis 64 may be collinear. Thus, in some embodiments, a portion of the carrier 62, such as the inner nut portion 82, may extend at least partially through the central opening 120. It should be noted that the lead screw 52 and carrier 62 will typically not engage the sun gear 100, but merely include portions contained within the central opening 120. Thus, the lead screw 52 and carrier 62 may rotate within the central opening 120 without directly engaging the sun gear 100. In some embodiments, a bearing assembly may be included in the central opening 120 between the carrier 62, such as the inner nut portion 82 thereof, and the sun gear 100. This bearing assembly may facilitate relative rotation without direct engagement. In other embodiments, it should be understood that the inner nut portion 82 need not extend through the central opening 120.
An epicyclic gear assembly 56 according to the present disclosure may further include a ring gear 130. The ring gear 130 may at least partially surround other gears of the epicyclic gear assembly 56, such as the planet gears 102. Further, the ring gear 130 may be integral with or coupled to the gearbox 60. In exemplary embodiments as shown, the ring gear 130 may be fixed, such that no rotation occurs during operation of the epicyclic gear assembly 56. The planet gears 102 may thus rotate within the ring gear 130. Alternatively, however, the ring gear 130 may be rotatable, and may, for example, be the output gear coupled to the lead screw 52.
A motor 140 may be coupled to the drive gear 104 to drive the drive gear 104 and thus the epicyclic gear assembly 56. For example, as shown, a pin 142 may extend through a central opening in the drive gear 104, such as along the central drive axis 114, to support the drive gear 104 thereon. This pin 142 may further be coupled to the motor 140, and may typically be the shaft of the motor 140. For example, a mechanical fastener, such as a nut-bolt combination, a rivet, a screw, a nail, or other suitable mechanical fastener may couple the pin 142 to the motor 140, or the pin 142 may extend through an opening in the motor 140, or the pin 142 may be integral with the motor 140. Operation of the motor 140 may cause the pin 142 to rotate. Rotation of the pin 142 may drive rotation of the drive gear 104.
Any suitable materials may be utilized to form the various components of a drive system 50, such as the various gears and other components of the epicyclic gear assembly 56, according to the present disclosure. In exemplary embodiments, any of a variety of polymers, such as in exemplary embodiments thermoplastics, may be utilized.
In particular, materials suitable for forming components according to the present disclosure are commercially available and referred to as self-lubricating materials, such as polyoxymethylene (Acetal or POM) or polyetheretherketone (PEEK). These self-lubricating materials permit quiet long-term operation.
Suitable acetal resins generally are copolymers or homopolymers containing at least 90 mole %, preferably at least 95% mole % of oxymethylene units in the main chain. Preferredly, the acetal resins generally have a melt flow rate (MFR) (according to ASTM D-1238-79) at 190 C and under a load of 2.16 kg, of 0.1 to 50 g/10 min., preferably 0.2 to 30 g/10 min., more preferably 1.0 to 20 g/10 min, and most preferably from 5 to 15 g/10 min.
The preferred polyoxymethylene molding compositions comprise from 0.1 to 50.0% by weight of a tribological modifier, from 0.01-0.5% by weight of one or more stabilizers which contain at least one ring nitrogen atom, and from 0.05 to 1% by weight of a lubricant, for example an ester of a polyhydric alcohol and a fatty acid. The molding composition or the molding can moreover comprise other components, e.g. up to 0.5% by weight, preferably up to 0.2% by weight, of a metal salt fatty acid, b.9) carboxylic acid, up to 1.0% by weight of an antioxidant; and for UV protection, a sterically hindered phenol compound, up to 1.0% by weight of at least one other stabilizer, preferably from the group of the benzotriazole derivatives or benzophenone derivatives or aromatic benzoate derivatives. The preferred polyacetal materials are available under the CELCON or HOSTAFORM brands from Ticona worldwide.
It should be understood that the present disclosure is not limited to components formed from the above disclosed materials, and rather that any suitable materials, such as metals or metal alloys or otherwise, are within the scope and spirit of the present disclosure.
These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.
The present application claims filing benefit of U.S. Provisional Patent application 61/625,817 having a filing date of Apr. 18, 2012 and which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61625817 | Apr 2012 | US |
