Abstract:
A clutch actuator has a housing with a load bearing element disposed within it. A force application element disposed within the housing applies force to the load bearing element. A stop assembly includes a retaining stopper between the load bearing element and the force application element. The stopper is dimensioned relative to a retainer and to the load bearing element to stop movement of said load bearing element relative to said retainer in the absence of a force application, and the stopper is dimensioned relative to said retainer and to said load bearing element to allow movement of said load bearing element relative to said retainer when force is applied against the load or when is force is released toward the load. One surface of the retainer, the stopper or the load bearing element is textured.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    None.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         APPENDIX  
         [0003]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    This invention is in the field actuators for actuating mechanical devices, especially traction devices such as Bowden cables used to move ergonomic supports in seats, particularly automobile seats.  
           [0006]    2. Related Art  
           [0007]    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.  
           [0008]    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&#39;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&#39;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.  
           [0009]    U.S. Pat. Nos. 5,397,164 and 6,334,651 B1 are incorporated herein by reference.  
           [0010]    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. Common to all of the mechanical devices and some of the electrical devices is the use of some type of friction surface. Whatever component takes up the Bowden cable wire must move past a friction surface, engage the friction surface to hold a selected position, and then release from the friction surface so that the component to which the wire is attached may return. The material of which these actuators are built, especially clutch type mechanical actuators, are typically plastic and sintered metal with steel bearings. Clutch actuators involve a cam and bearing arrangement in which the bearing floats with actuator movement to a selected position. The bearing locks between a cam and an enclosing ring or race to hold a selected position, and is thereafter releasable for a return movement.  
           [0011]    Hitherto, manual clutch actuators have had problems with slippage and low durability in the interaction between plastic, sintered metal, and steel components. There is a need for an actuator, particularly a manual clutch actuator, that does not slip and does not wear out.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention is a novel actuator having a friction surface. In one preferred embodiment, the actuator is a manual clutch type actuator. The actuator has a housing with a seat for a Bowden cable sleeve. Inside the housing is a take up wheel or drum for putting tractive force on a Bowden cable wire and pulling it from a Bowden cable sleeve by taking the wire up on the wheel. The wheel is coaxial with and fixed to a hub having a plurality of cam shaped surfaces. The hub is encircled by a ring. The cam shaped surfaces on the hub, when assembled with the ring, form constricting channels. Bearings are disposed within the constricting channels. In one preferred embodiment, the bearings are roller bearings made out of steel. Also disposed within the constricting channels are cylindrical rubber springs. The ring is fixedly attached to the housing, which is to be fixedly mounted to a seat frame. The hub and take up drum are linked to a lever or handwheel with which the user turns the actuator. Particularly, the lever or handwheel is connected with a disk that is coaxial with and axially adjacent to the hub. The disk has axially projecting fingers that extend into the constricting channels between the circular hub and its enclosing ring. These fingers are disposed to put rotational pressure on the steel rollers adjacent to them. The constricting channels are separated by stops which are an integral part of the hub. The fingers are also disposed to abutt the hub stops and, when turned, exert rotational pressure on them. Thus each finger abuts a hub stop on one side and a steel roller on the other side. Each steel roller is separated from its adjacent hub stop by the rubber cylindrical spring. Each steel roller is abutted on either side by the disk finger and the rubber spring. Each rubber spring is abutted on either side by the steel roller and the hub stop. Each hub stop is abutted on either side by the rubber spring and the next finger extension of the disk.  
           [0013]    In operation, the manual clutch actuator performs the functions required of it: movement with force, position holding and release. Movement with force is achieved by the user turning the lever or handwheel, which turns the disk, which revolves the fingers to exert force against the abutting hub stops. The entire hub thereby moves in a first direction, which direction turns the attached take up drum, which takes up the Bowden cable wire and exerts tractive force on it. The wire then moves the lumbar support on its other end.  
           [0014]    When the user releases the lever or handwheel, the user&#39;s weight against the pressure surface of the lumbar support will put force on the Bowden cable wire tending to draw it back into the sleeve. The pressure surface and Bowden cable wire are held stopped against this force by the action of the clutch in the actuator. That is, the configuration of the hub with the enclosing ring forms constricting channels which become more narrow at one end. The steel roller disposed within the constriction channel in sized so that it may move freely in the wide end of the channel, but cannot fit in the narrow end of the channel, causing it to jam or wedge when moved towards the narrow end of constricting channel. The return force or load on the hub exerted by the Bowden cable wire rotates the hub so that the steel roller is biased towards the narrow end of the constricting channel. The roller jams there, preventing further rotation of the hub which holds the wire. Consequently the lumbar support pressure surface connected to the wire is held in the selected position.  
           [0015]    In order to release the held wire and pressure surface, the user turns the lever or handwheel in a direction opposite the first direction in which he turned it. This direction is the same direction torsionally as the load. The disk fingers linked to the lever push the steel rollers towards the rubber springs, compressing the springs and advancing the steel rollers into the wider part of the constricting channels so that the hub may rotate freely relative to the ring. This releasing action allows the actuator to complete its final necessary action, releasing the clutch to turn so that the lumbar support can return to its original position.  
           [0016]    It is apparent that the function of holding the selected position against the load is achieved by the frictional action of the steel roller between the inner surface of the fixed ring and the outer cam surface of the rotating hub. In order that the selected position to be accurately held and that there be a satisfying immediacy to the holding of that position, the frictional relationship between the steel roller, ring and hub must not slip. Additionally, repeated actions of holding and releasing should not wear down the surfaces of the ring or hub to create a groove or indentation and should not wear down the surface of the steel rollers to flatten them. Such wear leads to increased slippage and failure of the device to accurately hold the selected position.  
           [0017]    The present invention incorporates a novel friction surface to the frictional relationship between the ring, roller and hub. The frictional surface is a textured surface. In one preferred embodiment, grooves are machined into the inner surface of the ring. One size groove is circumferential and another size groove is axial. These grooves ensure a tight, non-slip lock with the steel roller. These grooves also clearly reduce wear on all components and increase the durability of the clutch actuator.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings:  
         [0019]    [0019]FIG. 1 is a lumbar support with a manual actuator.  
         [0020]    [0020]FIG. 2 is a perspective view of a manual clutch actuator, assembled.  
         [0021]    [0021]FIG. 3 is an exploded view of a manual clutch actuator.  
         [0022]    [0022]FIG. 4 is a perspective view of a partially assembled manual clutch actuator.  
         [0023]    [0023]FIG. 5 is a top view of a partially assembled manual clutch actuator.  
         [0024]    [0024]FIG. 6 is a perspective view of the ring of the manual clutch actuator.  
         [0025]    [0025]FIG. 7 is a close up of the textured surface of the ring of the manual clutch actuator. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Referring to the accompanying drawings in which like reference numbers indicate like elements, FIG. 1 depicts an ergonomic support, which in FIG. 1 is a lumbar support  2 , for an automobile seat. Movement of the lumbar support  2  is achieved by a manual actuator  4  which is linked to the lumbar support by Bowden cable  6 . Bowden cable  6  has a sleeve  8  which is attached to a first portion  12  of the moveable pressure surface  10  of the lumbar support  2 . Inside the Bowden cable sleeve and disposed to slide axially through it is a Bowden cable wire  14  attached to another portion  16  of the moving pressure surface of the lumbar support  2 . The actuator  4  puts a tractive force on the Bowden cable wire  14  pulling it through the Bowden cable sleeve  8 . This moves the second portion  16  of the moveable pressure surface of the lumbar support towards the first portion  12  of the moveable pressure surface of the lumbar support, bowing it into an arch shape that gives the seat occupant lumbar support.  
         [0027]    [0027]FIG. 2 is a perspective view of an assembled clutch actuator  4 . FIG. 2 depicts one of many possible housing configurations enclosing the essential components of an overrunning clutch type manual actuator. Housing  20  includes two optional seats  22  for a sleeve of a traction cable such as a Bowden cable. Only one seat will be used in assembly. Axle  24  turns the clutch. It will be assembled with a lever or handwheel (not shown).  
         [0028]    [0028]FIGS. 3, 4 and  5  are exploded, perspective and top views of the clutch actuator of the present invention. Ring  30  is installed in housing  20  and fixedly attached to it. Hub  40  is assembled inside ring  30  and coaxial with it. In the depicted embodiment, hub  40  has three hub stops  42 . Hub stops  42  are dimensioned to closely cooperate with an inner surface  32  of ring  30 . In many embodiments, hub  40  is fabricated from sintered metal.  
         [0029]    Hub  40  has an interface  44  which is attached during assembly to an extension  52  of a Bowden cable wire take up drum  50 . Seat  22  in housing  20  holds a Bowden cable sleeve end against the tension to be applied by the actuator  4 . From the sleeve end, a Bowden cable wire extends through housing  20  to where it is seated on take up drum  50 . Take up drum  50  has an extension  52  which interlocks with the interface  44  of hub  40 . Accordingly, rotation of hub  40  turns take up drum  50 . When the rotation of hub  40  and drum  50  is in a first direction, traction is applied to the Bowden cable wire, pulling it from the Bowden cable sleeve, which will have an actuating effect on the lumbar support at the other end of the Bowden cable.  
         [0030]    Assembled on top of the ring  30  and hub  40  is disk  60 . When a user turns a handwheel or lever (not shown) the action will turn axle  24 . Turning axle  24  turns disk  60 . Disk  60  has downward projecting “fingers” or extensions  62 . Fingers  62  project downward onto the plane of ring  30  and hub  40  in order to interact with them and transmit force exerted by the user on the lever or handwheel and transferred through the axle  24  to disk  60 .  
         [0031]    The assembly of ring  30  and hub  40  creates between them constricting channels  34 . The constricting channels  34  are each bounded by the inner surface  32  of ring  30 , the outer surface  46  of hub  40 , the releasing face  47  of hub stop  42 , and the tensioning face  48  of another hub stop  42 . Outer surface  46  of hub  40  is eccentric or cam shaped. In alternative embodiments, outer surface  46  of hub  40  may be perfectly circular, and assembled with a ring  30  whose inner surface  32  is eccentric or cam shaped. In either case, the assembly of ring  30  and hub  40  must define a constricting channel  34 . In the case of bi-directional clutches, the constricting channel may be narrowed at both ends and wider in the middle. However, in the depicted embodiment, each constricting channel  34  is narrower towards a tensioning face  48  of a hub stop  42 , and wider towards a releasing face  47  of another hub stop  42 .  
         [0032]    In assembly, a rubber grommet  36  is disposed immediately against the releasing face  47  of hub stop  42 , to serve as a spring. Alternatively, other types of springs may be used. In assembly, a bearing  38  is disposed immediately adjacent to rubber grommet  36 . Bearing  38  may be any known shape or configuration, however, in the depicted embodiment, bearing  38  is a steel roller. The steel roller  38  is dimensioned such that its diameter cannot simultaneously touch inner surface  32  of ring  30  and outer surface  46  of hub  40  when roller  38  is in the wider portion of the constricting channel  34  closer to releasing face  47  of hub stop  42 . Steel roller  38  is also dimensioned such that it cannot fit between inner surface  32  and outer surface  46  at the narrow end of the constricting channel  34  closer to the tensioning face  48  of another hub stop  42 . It is apparent, then, that movement of hub  40  relative to ring  30  in a first direction, which is clockwise in the embodiment shown in FIG. 5, will cause steel roller  38  to wedge or jam in between inner surface  32  and outer surface  46 . This jamming stops and holds the relative movement of hub  40  and ring  30 . Because the Bowden cable wire is fixed to wire drum  50  and wire drum  50  is attached to hub  40  such that drum  50  can only move in unison with hub  40 , the stopping of hub  40  by the jamming of steel roller  38  will hold the assembly and wire against further clockwise rotation. This of course holds the tension of the assembly on the Bowden cable wire against the clockwise torque exerted on the assembly by the weight of a seat occupant pushing against the pressure surface of the lumbar support. In this manner, a user selected position is held in place.  
         [0033]    It is apparent that the components described herein maybe reversely assembled in a mirror image fashion so that they hold against a counter clockwise torque. In assembly, left and right hand seat versions of the actuator may be easily assembled by simply turning the hub over, and seating the traction cable sleeve in one or the other seat  22 .  
         [0034]    In operation, the actuator has two other functions to perform in addition to stopping rotation in order to hold a selected position. The first of these is tensioning the actuator in order to pull the Bowden cable wire out of the Bowden cable sleeve and exert tractive force on the lumbar support at the other end of the Bowden cable. The other function is to release tension. Releasing the wedging stop of the steel roller and allowing the hub to counter rotate, releases the tension on the Bowden cable, allowing the wire to retract into the cable and thereby allowing the pressure surface of the lumbar support to return to the original, flatter position.  
         [0035]    The tensioning function is as follows. The user turns the lever or handwheel (not shown) thereby turning axle  24  in second direction. In the embodiment depicted in FIG. 5, the second direction is counter clockwise. Turning the axle  24  turns the disk  60  and consequently turns the disk fingers  62 . Because disk fingers  62  extend downward into the constricting channels  34 , counterclockwise rotation of the fingers  62  brings them into contact with the tensioning face  48  of each hub stop  42 . The fingers  62  drive the hub in the second direction, counter clockwise in FIG. 5, which causes the narrow end of the constricting channel to recede away from steel rollers  38 . The steel rollers  38  are thereby released, have room to move in the wider portion of constricting channels  34 , and may rotate along with hub stops  42  in the second, counter clockwise direction. When the user has moved the assembly and, thru it, the lumbar support, to a position she finds comfortable, she releases manual pressure on the lever and axle  24 . When the force being exerted on the disk finger  62  in the second, counter clockwise direction stops, the return force of the Bowden cable wire which is exerted on hub  40  through wire take up drum  50 , is received as torque by the assembly in the clockwise first direction. Rubber grommet springs  36  expand and exert a bias in the second, counterclockwise direction on steel rollers  38 . The combination of these two effects moves steel roller  38  towards the narrow end of constricting channel  34  where it wedges or jams. The clutch is stopped, and the selected position held.  
         [0036]    In order to return the lumbar support to its original, flatter position, the clutch assembly need only release the stopping action of the steel roller  38 . Accordingly, the user may turn axle  24  in the first, clockwise direction. This causes fingers  62  to push steel rollers  38  in the first, clockwise direction and into the wider portion of constricting channel  34 . This releases hub  40  to move relative to ring  30  and consequently allows hub  40  and the attached Bowden cable wire take-up drum  50  to rotate relative to the ring  30 . This freed rotation allows the Bowden cable wire to be drawn back into the Bowden cable sleeve, in turn allowing the lumbar support to return to its original, flatter position.  
         [0037]    It will be immediately apparent to those of skill in the art that for the clutch actuator to give a feeling of immediate response and precision to its user, the tolerances between the outer surface  46  of hub  40 , the inner surface  32  of ring  30  and the steel roller  38 , must be relatively small. Stated another way, upon the release of user applied tension in the second, counter clockwise direction—the tensioning direction—steel roller  38  cannot be allowed to rotate any appreciable distance before it jams and stops the assembly in the selected position. If the steel roller fails to jam immediately the user will feel an undesirable slippage of the assembly. In addition to the unsatisfactory feel of such slippage, slippage also causes the need for a readjustment of the assembly and lumbar support to return to the desired position.  
         [0038]    Even when the tolerances between the inner surface  32  of ring  30  and the outer surface  46  of hub  40  and the steel roller  38  are kept reasonably close, if all three surfaces are smooth, some slippage is likely to occur, at least in those lumbar support positions where tension is highest. Non-slipping interaction between the surfaces is needed.  
         [0039]    In addition to the possibility of initial slippage, in the lifetime of actuator use the repeated interaction of the surfaces over time creates wear, exacerbating any slippage problem. Steel roller faces may be flattened by repeated use. Inner surface  32  of ring  30  may be worn or eroded, thereby extending the length of the wider portion of constricting channel  32  and wearing gaps between the interacting surfaces, increasing the occurrence and degree of slippage. Finally, the outer surface  46  of hub  40 , especially in those embodiments wherein hub  40  is made of sintered metal, may be likewise worn so that the desired curvature of the cam surface  46  is lost, again producing increased incidence and degree of slippage. A more durable interaction of surfaces would be desirable.  
         [0040]    [0040]FIG. 6 is a perspective view of ring  30 . Inner surface  32  has been textured. Texturing the surface of inner surface  32  of ring  30  increases the frictional co-efficient of inner surface  32  in its interaction with steel roller  38 . Early in the life cycle of the actuator, the textured surface  32  promotes a quicker “grab” of the roller  38 , thereby decreasing slippage. The textured surface is also more resistant to wear, so that the degree and incidence of slippage does not increase over the lifetime of the actuator regardless of repeated usage.  
         [0041]    [0041]FIG. 7 is a close-up depiction of one embodiment of the texturing of surface  32 . In the depicted embodiment, the inner surface  32  of ring  30  has been machined with a helical groove. FIG. 7 is a close-up section of inner surface  32  showing many grooves. Axis X in FIG. 7 shows the direction of these grooves. In the depicted embodiment, the many grooves are actually the same groove, because they have been machined in a helical fashion. Alternatively, several interlocking helical grooves or separate grooves may be used. In the depicted embodiment, the grooves are one to three microns deep and one to three microns wide. A preferable range may include about 1.0 to 3.5 microns, with a most preferred range of about 1.6 to 2.6 microns.  
         [0042]    In one embodiment the inner surface  32  is hardened to a RockwellC 30 HRC with a micro hardness of about 55 HRC as measured according to ASTM E140-67. A preferable range may include about 26 to 46 HRC, with a most preferred range of 30 to 41 HRC. Micro hardness may be from about 40 to 70.  
         [0043]    Additionally further texturing may be desirable. Grooves, ridges, or other texturing may be machined in a direction co-axial with the ring  30 , along the Y axis in FIG. 7. Such co-axial grooves would then be perpendicular to the direction of travel of hub  40  and roller bearings  38 . In one embodiment, the dimensions of such a micro texture would be around 0.2 microns. A preferable range may be about 0.1 to 0.3 microns.  
         [0044]    Other embodiments within the scope of the present invention may place 1 to 3 micron grooves in the co-axial direction and 0.1 to 0.3 micron grooves in the circular direction. Other  
         [0045]    As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or 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.