Patent Application
20060163924
Not applicable.
1. Field of the Invention
This invention relates generally to actuators and, more particularly, to a transmission improvement for an actuator.
2. Related Art
Many mechanical devices need to be moved to a user selected position and then held there against a force that is biased to return the device to its original position. Such devices are commonly used for ergonomic supports in seating, especially lumbar supports for automobile seats. Lumbar supports exert a comfortable force against the lumbar spine of a seat occupant. This force is applied mechanically through a wide variety of configurations including arching, bending, tightening, extending or otherwise moving a pressure surface. Pressure surfaces are of an equally wide variety including straps, paddles, “baskets,” arching surfaces, bowed surfaces and so forth. These devices must allow the user to select a desired position for the pressure surface, and thereafter hold that position after the user has released whatever device and linkage has been used to move the pressure surface to the selected position. The linkages are of a wide variety including rods, levers, springs, cables, and especially coaxial traction cables such as Bowden cables. The linkage, for example a Bowden cable, has a connection to the lumbar support at one end and a connection to an actuator at the other end. The actuator is positioned where the user may operate it, typically at the edge of the seat.
There is a great variety of actuator structures used for these purposes, both mechanical and electrical. They share in common the function of moving the pressure surface to a selected position, and then holding the pressure surface in that position against a force exerted by the seat occupant's weight. That force is biased towards returning the pressure surface to its original position, which is usually flat. The most common linkage, the Bowden cable, has a flexible conduit, also called a “sleeve” or “sheath,” through which runs a coaxially sliding wire. Actuators have a seat for the end of the sleeve and seat for the end of the wire. The opposite ends of the wire and sleeve are connected to different portions of the lumbar or other ergonomic support, such that pulling the wire through the sleeve moves the pressure surface to the desired position. Accordingly, the most commonly used actuators are designed to pull a Bowden cable wire through a Bowden cable sleeve. The actuators must exert the force necessary to pull the wire through the sleeve to actuate the lumbar support. They must also hold the wire against the return force of the passenger's weight on the lumbar support pulling the wire back into the sleeve. In addition the actuators must also be able to release the holding force from the wire so that the user may return the ergonomic device to its original position or to another selected position.
Actuators achieve these necessary functions of movement, holding and release through a variety of mechanisms. Electronically powered actuators frequently use gears connected to take up wheels or drums for pulling the Bowden cable wire. Manual actuators may also use gears and take up drums, but more typically include a brake, ratchet or clutch. Brakes, ratchets and clutches are powered by levers or hand wheels turned by the users hand.
There remains a continuing need in the art for reducing the size and the profile of the assembled actuator. There also remains a continuing need in the art for easing and streamlining assembly of the component parts of the actuator. Finally, there is a continuing need to reduce the number, and consequently the expense, of the components to be assembled into actuators.
The invention is an actuator having an output gear, a pinion, a drive shaft, a housing, and a spring. The output gear is adapted to receive a traction element. The pinion is in driving communication with the output gear, and the drive shaft is interconnected with the pinion. The housing is adapted to receive the output gear and the drive shaft.
The spring is circumjacent the drive shaft and located in a position intermediate the drive shaft and the housing. In a static state, the spring frictionally engages the housing to prevent rotation of the drive shaft. Because the pinion is connected to the drive shaft, the spring also prevents rotation of the pinion. Moreover, due to the engagement of the pinion with the output gear, the spring also prevents rotation of the output gear. However, when a dynamic force is applied to the drive shaft, such as when the drive shaft is rotated via a knob or lever, the spring is disengaged, thereby allowing rotation of the drive shaft, and, thus, the pinion and the output gear. Because the spring imparts only a nominal stress on the housing and the drive shaft, it is possible to make the housing and the drive shaft from plastic.
The actuator may be used to operate an ergonomic device, such as a lumbar support. As an example, the output gear may be rotated to draw or compress a traction element for adjustment of the ergonomic device. When a dynamic force is applied to the drive shaft, the spring frictionally disengages from the housing to allow rotation of the output gear, and thus movement of the traction element. When the dynamic force is released, the spring frictionally engages the housing such that the output gear is locked in position, thereby preventing further movement of the traction element.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
The arching portion 112 is moved via a traction device. In the depicted embodiment, the traction device is a bowden cable 116. The bowden cable 116 is comprised of an outer, flexible sleeve 122, which retains and directs a wire 124 (best seen in
Hence, it is apparent that the most rudimentary function of any actuator is to draw the bowden cable wire 124 through the bowden cable sleeve 122 for operation of the ergonomic device. If an alternative traction device were elected as a design choice, the most rudimentary function of the actuator would remain to draw the tractive device, whether it is a rod, cable, or otherwise, in a direction applying tractive force to actuate the ergonomic device. The present invention may be applied to any such tractive devices. In another alternative design choice, compressive pressure may be used to bow an archable surface. The present invention may likewise be used to drive such a compressive mechanism.
As best seen in
The geared portion 32 mates with the output gear 20. In the depicted embodiment, the geared portion 32 has first gear teeth 26 that mesh with second gear teeth 28 of the output gear 20. A lubricant (not shown), such as grease, may be applied to the first gear teeth 26 and the second gear teeth 28 in some embodiments. While gear teeth are used in the depicted embodiment to mate the pinion 16 and the output gear 20, other similar features may be used. What is important is that the pinion 16 and the output gear 20 are locked together so that they cannot rotate independently of one another. It is important to note that the arrangement of the pinion 16 and the output gear 20 provide an effective gear reduction. In the depicted embodiment, the pinion 16 rotates about 4.5 times for each revolution of the output gear 20. In this manner, a high speed but low torque rotation of the pinion 16 may be used to rotate the output gear 20.
The bearing portion 34 supports the pinion 16. In the depicted embodiment, the bearing portion 34 has a cylindrical shape. The bearing portion 34 is received by a first void 37 in the cap 14. In some embodiments, lubricant, such as grease, may be applied to the first void 37 to reduce friction between the cap 14 and the bearing portion 34. Thus, the pinion 16 and the drive shaft 18 rotate about the first void 37 and the bearing portion 34.
The output gear, or pulley, 20 rotates about the gear shaft 22, which is affixed to the housing 12 and the cap 14. Lubricant, such as grease, may be applied to the gear shaft 22 in some embodiments. In the depicted embodiment, the housing 12 and the cap 14 each have a second void 35 that receive a respective end of the gear shaft 22. Thus, the gear shaft 22 is captured between the housing 12 and the cap 14. In the depicted embodiment, the gear shaft 22 has a diameter of 5 mm. The output gear 20 depicted in
The drive shaft 18 rotates within the housing 12 and slides over the pinion 16, thereby engaging it. The drive shaft 18 includes a mounting surface 29. A device providing mechanical advantage may be mounted to the mounting surface 29. As an example, the knob 50 may be mounted to the mounting surface 29, and a user may rotate the drive shaft 18 via the knob 50. The drive shaft 18 has a first shoulder 23 and a guide surface 27. The drive shaft 18 also includes a second shoulder 51. As best seen in
The spring 24 is located intermediate the drive shaft 18 and the housing 12. In other words, the spring 24 lies circumjacent the drive shaft 18 and adjacent the housing 12. In the depicted embodiments, the spring 24 lies over the guide surface 27 and rests upon the first shoulder 23. The spring 24 selectively engages an inner surface 52 (best seen in
In a dynamic state, the spring 24 is frictionally disengaged from the housing, thereby allowing rotation of the drive shaft 18, and, thus, the pinion 16 and the output gear 20. Because the spring imparts only a distributed nominal stress on the housing 12 and because the pinion 16 requires a small braking torque, it is possible to make the housing 12 from plastic, thereby reducing the overall cost of the actuator 10.
The drive shaft 18 includes a first face 64 and a second face 66. Similarly, the pinion 16 includes a third face 68 and a fourth face 70. The tabs 60, 62 ride on the faces 64, 66, 68, 70 to either expand or collapse the spring 24. In a first example, the drive shaft 18 may be rotated in a first direction such that the second face 66 contacts the second tab 62 and moves the tab 62 in the first direction to reduce the diameter of the spring 24. In a second example, the pinion 16 may be rotated in a second direction due to a force being applied to the output gear 20 by the bowden cable 116. When the pinion 16 is rotated in the second direction, the fourth face 70 of the pinion 16 contacts the second tab 62 and moves the second tab 62 in the second direction such that the diameter of the spring 24 is increased. By increasing the diameter of the spring 24, the amount of pressure exerted by the spring 24 on the housing 12 is increased, thereby increasing the friction between the two surfaces. As such, the pinion 16 is effectively braked.
Referring now to
The output gear 20 has a notch 42 for receiving installation of the bowden cable wire end stop 126. The bowden cable wire 124 would then be wrapped partially around the output gear 20 and lead out through one of the passageways 36. The output gear 20 may include a feature to receive the bowden cable wire 124. For example, the output gear 20 may have a groove 44 to receive the bowden cable wire 124. In this configuration, rotation of the output gear 20 wraps the bowden cable wire 124 further around the output gear 20 which effects a shortening of the bowden cable wire 124 at the opposite end of the bowden cable 116. This shortening also draws the bowden cable wire 124 through the bowden cable sleeve 122 applying the desired traction to the ergonomic device to which the other end of the bowden cable wire 124 and bowden cable sleeve 122 are attached.
The actuator 10 also includes an opening 40. To assemble the bowden cable 116 to the actuator 10, the bowden cable wire end stop 126 is placed through the opening 40 and into the notch 42. The bowden cable wire 124 is then pulled through the slot 38 until the bowden cable sleeve 122 is beyond the end of the first channel 46 or the second channel 48. The bowden cable sleeve 122 is then placed within the passageway 36 until it contacts a wall 56 (best seen in
Typically, the actuator 10 is used to limit the operation of the ergonomic device. For example, if the ergonomic device is a lumbar support, then the actuator 10 may be used to limit the travel of the lumbar support to prevent its over travel. This may be accomplished in several ways. For example, as best seen in
Alternatively, and referring once again to
The actuator 10 is assembled by providing a housing, placing a spring over a drive shaft, inserting the spring and the drive shaft into the housing, interlocking a pinion with the drive shaft, inserting a gear shaft into the housing, and placing a drive gear onto the gear shaft and in a driven relationship with the pinion. In some embodiments, an optional step is mounting a cap to the housing. A further step may be to place a tab of the spring within a gap located between the pinion and the drive shaft.
As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.
