Abstract:
A method of operating a door return device for a vehicle door having a travel path including an easy-reach position and a fully open position. A housing is coupled to one of the door or the door frame and has a chamber containing a working fluid. A link is coupled to the other one of the door or the door frame and is movable into and out of the housing in response to travel of the door. An end-damping piston slides in the chamber and includes a fluid passage between opposite sides. A return spring is disposed between the end-damping piston and one longitudinal end of the chamber. When the return spring is substantially unloaded then the end-damping piston is positioned relative to the one longitudinal end such that the door is away from the fully open position at least as far as the easy-reach position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. nonprovisional patent application Ser. No. 12/104,481, filed Apr. 17, 2008, which is incorporated herein by reference. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    The present invention relates generally to end-of-movement damping for doors of motor vehicles, and more specifically to a return device for assisting in the re-closing of a vehicle door after the opening motion has been damped. 
         [0003]    Wide opening doors for motor vehicles (i.e., a door with a large range of movement to clear the door opening) have several advantages. From a consumer standpoint, a wider opening is beneficial when needing to load large items into the vehicle. From a manufacturer standpoint, since many assembly operations are performed after a door has been installed but with the door swung open to its maximum extent (e.g., connecting wiring or other components in the hinge area between the forward edge of the door and the door frame), these assembly operations become easier the greater the opening range of the door. 
         [0004]    A disadvantage of a wide opening door becomes evident when a vehicle occupant attempts to close the door. After being seated inside the vehicle, the occupant may be at too great a distance from the door pull handle to be able to conveniently reach it. In addition, the door must initially be pulled in the radial direction (i.e., toward the back of the vehicle instead of toward the occupant). This results in a non-ergonomic motion being required of the seated occupant since the initial sideways movement has to be generated with the arm outstretched. 
         [0005]    So that the manufacturing advantage of a wide opening door can be realized without creating customer inconvenience when closing the door, it is known to install door hinges with a wide range of motion to facilitate the necessary assembly operations. Once those operations are completed at the assembly plant, a door check link is connected between the door and door frame that thereafter restricts the range of door motion so that the vehicle occupant is better able to reach it for closing. However, it becomes more difficult to load large items through the door opening because of interference from the door. 
         [0006]    Door check links have traditionally provided detents to preferentially hold an open door in various predetermined positions, including at the fully open position. More recently, door holding units have been introduced using hydraulic cylinders to provide positive retention of a manually positioned door at infinitely many positions across the full range of door motion. One example of such a door holding unit is the DORSTOP® device from Stabilus GmbH of Koblenz, Germany. As shown in U.S. Pat. No. 7,066,310, it is also known to provide damping (i.e., energy absorption) at the fully open end of the door travel using a separate end-damping piston that is acted upon by a main holding piston. In the prior art, even though a reset spring may be provided to reset the end-damping piston to its original position after being released by the holding piston, the door has been kept in its fully open position by the holding piston until the door is manually moved out of the open position by the user. In fact, the reset spring was intentionally designed not to induce any door motion since the device was meant to hold the door in any position in which is was placed by the user. 
       SUMMARY OF INVENTION 
       [0007]    The present invention combines in a single device the end-damping of door motion with a slow, controlled partial return of the door from the fully open position to provide an easy-reach closing capability for a wide opening door. 
         [0008]    In one aspect of the invention, a door return device is provided for a vehicle door having a travel path between a closed position in a door frame and a fully open position. The travel path includes an easy-reach position spaced by a predetermined distance from the fully open position. A housing is adapted to be coupled to one of the vehicle door or the door frame and has a chamber containing a working fluid. A link is adapted to be coupled to the other one of the vehicle door or the door frame and is movable into and out of the housing in response to travel of the vehicle door along the travel path. An end-damping piston is slidable in the chamber and is coupled to the link, wherein the end-damping piston partitions the chamber into first and second subchambers. The end-damping piston includes a surface for providing a fluid passage between the first and second subchambers. A return spring is disposed between the end-damping piston and one longitudinal end of the chamber. When the return spring is substantially unloaded, then, the end-damping piston is positioned relative to the one longitudinal end such that the vehicle door is away from the fully open position at least as far as the easy-reach position. Manual opening movement of the vehicle door into the fully open position is damped by flow of the working fluid through the fluid passage. Manual opening movement of the vehicle door into the fully open position loads the return spring. When the vehicle door is released at the fully open position it gradually moves to the easy-reach position by the unloading of the return spring, and the gradual closing movement of the vehicle door is damped by flow of the working fluid. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a diagram showing a range of motion for a vehicle door. 
           [0010]      FIG. 2  is a cross-sectional view of a door return device in a position corresponding to the door being more closed than an easy-reach position. 
           [0011]      FIG. 3  is a cross-sectional view of a door return device in a position corresponding to the door being in its fully open position. 
           [0012]      FIG. 4  is a cross-sectional view of a door return device in a position corresponding to the door being in the easy-reach position. 
           [0013]      FIG. 5  is a longitudinal cross section showing a tapered groove for controlling fluid flow around the end-damping piston. 
           [0014]      FIG. 6  is a top, exterior view of the housing with the tapered groove. 
           [0015]      FIG. 7  is a cross section taken along line  7 - 7  of  FIG. 6 . 
           [0016]      FIG. 8  is a top view showing an alternative embodiment of a door return device for a sliding door. 
           [0017]      FIG. 9  is a cross section of a door return device adapted for the embodiment of  FIG. 8 . 
           [0018]      FIG. 10  is a cross section of an alternative door return device adapted for the embodiment of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring to  FIG. 1 , a vehicle door  10  is attached to a door frame  11  by a hinge  12 . Door  10  is normally opened using an outside door handle  13  and closed using an inside door handle  14 . Of course, door  10  can also be moved by pushing on other portions thereof. Door  10  can be manipulated by a user (e.g., vehicle occupant) to swing through a range of motion according to an arc  15  with a fully open position  16  and an easy-reach position  17 . A door hold &amp; return device  18  is coupled between door  10  and frame  11  to provide a door holding function for any position between the door closed position and easy-reach position  17  where the user manually stops the door. An end-damping function is provided by device  18  between easy-reach position  17  and fully open position  16 . When the user releases door  10  (i.e., stops applying opening force) in the range between positions  16  and  17 , door  10  gradually returns to easy-reach position  17  by action of device  18  as will be described below. Device  18  is anchored to frame  11  at a position that does not coincide with the center axis of door rotation so that the greater the door opening angle the greater the extension of device  18 . Thus, device  18  is contracted to its shortest length when door  10  is in its closed position and is extended to its maximum length when door  10  is in fully open position  16 . 
         [0020]    A first embodiment of a door holding and return device of the present invention is shown in  FIGS. 2-4 . Device  20  includes a housing  21  which may be preferably formed as a cylindrical shell having an interior space for containing various components and a working fluid  22  therein. For assembly purposes, housing  21  preferably comprises a plurality of sections that may be joined (e.g., welded) after installation of internal parts. A mounting block  23  is provided on housing  21  for mounting to one or the other of the door and the door frame. In a typical vehicle application, housing  21  may be mounted to an interior wall of a door shell. A link  24  extending from housing  21  has a mounting section  25  for mounting to the other of the door or door frame in a conventional manner. Within the inside of housing  21 , link  24  is fixedly connected with a hold piston  26  so that piston  26  and link  24  are jointly slidable within the interior chamber of housing  21 . A seal/guide  27  is mounted to one longitudinal end of housing  21  to slidingly accept link  24  so that working fluid  22  is not lost through a hole  28  where link  24  exits housing  21 . Hold piston  26  includes various valve structures for allowing working fluid  22  to pass through piston  26  when link  24  is forcibly moved in the longitudinal direction. The work required to force working fluid  22  through the valves and passages within hold piston  26  are what hold the door connected to link  24  at any desired position in the absence of a sufficiently large push against the door. 
         [0021]    In order to provide end damping, an end-damping piston  30  is slidably retained on link  24  between hold piston  26  and longitudinal end seal  27 . An orifice or passage way  31  (which may include an internal valve if desired) is provided in end-damping piston  30  to allow working fluid  22  to flow between opposite sides of end-damping piston  30  when it is forced to move. A return spring  32  is disposed between end-damping piston  30  and longitudinal end seal  27 . 
         [0022]    As shown in  FIG. 2 , return spring  32  is substantially unloaded (i.e., spring  32  is a compression spring with no compression forces being applied to it), and hold piston  26  is spaced from end-damping piston  30  such that the door is at a position somewhere between the closed position and the easy-reach position. Thus, hold piston  26  moves through fluid  22  in a conventional manner to provide infinitely many holding positions of the door across its movement range up to the easy-reach position. As the door is increasingly opened, hold piston  26  eventually contacts end-damping piston  30  at the moment the door enters the easy-reach position. When link  24  continues to move to the left as shown in  FIG. 3  as a result of the user opening the door past the easy-reach position, end-damping piston  30  moves in the same direction to compress spring  32 . As end-damping piston  30  moves through working fluid  22 , movement is damped because of the restricted flow provided by passageway  31 . The compression of return spring  32  provides additional damping or energy absorption as the door moves to the full open position, but the damping is primarily provided by the manipulation of working fluid  22  through passage  31 . By damping the opening energy of the door, there is less chance of the door bouncing back from the open position. 
         [0023]    When the operator eventually releases the door (e.g., after a large load has been successfully placed into the vehicle through the fully opened door), return spring  32  will have been compressed at least to some proportion of its maximum compression. In all previously known hold open devices, the hold piston would maintain its position at the fully open position and all other positions without being influenced by the return spring. In the present invention, however, return spring  32  provides a sufficient spring force to move end-damping piston  30 , link  24 , and hold piston  26  to the right until the easy-reach position is obtained as shown in  FIG. 4 . It should be noted that the end-damping and return function shown in  FIGS. 2-4  can be provided by devices either with or without including the holding function at positions more closed than the easy-reach position. Thus, end-damping piston  30  partitions the chamber of working fluid into first and second sub-chambers wherein the inner surface of passage-way  31  provides a fluid passage between the first and second sub-chambers. 
         [0024]    The present invention can be adapted to provide variable damping at different positions of the end-damping piston in order to achieve better energy absorption during full open and a more uniform return speed for the easy-reach function. As shown in  FIG. 5 , a tapered groove  33  is provided along the interior surface of housing  21  in the region traversed by piston  30  during the end-damping function. Tapered groove  33  has a variable cross-sectional area and provides an alternative flow path for working fluid  22  around an outer circumferential surface  34  of piston  30 . The taper of groove  33  causes the cross-sectional area available for flow of working fluid  22  to be reduced as piston  30  moves closer to the end of housing  21  (i.e., toward the fully open position). Thus, the amount of damping varies with changing position of piston  30  to provide an increased braking force as the door approaches the full-open position to thereby create a smoother stop to the door movement. Conversely, when the door is released and the automatic return to the easy-reach position is executing, return spring  32  provides progressively less return force the closer it gets to its unloaded position. Since groove  33  provides a progressively larger cross section for flow of working fluid  22 , spring  32  can maintain a more constant speed through the entire range of movement up to the easy-reach position. 
         [0025]    As shown in  FIGS. 6 and 7 , tapered groove  33  may preferably be obtained using a metal rolling process. Alternatively, cutting or drilling operations can be used to form the taper groove from the inside of housing  21 . Tapered groove  33  can be used with or without passage  31  in end-damping piston  30 . In a preferred embodiment, the average cross-sectional area of tapered groove  33  is approximately equal to the flow cross-sectional area of passageway  31 . The tapered profile of groove  33  can also be adapted to provide return speed profiles other than a substantially uniform speed, if desired. 
         [0026]    The present invention can also be utilized in conjunction with a sliding door in order to provide end-damping and easy-reach return functions without any hold function. As shown in  FIG. 8 , a sliding door  40  has a door bracket  41  pivotably connected with a roller bracket  42  that traverses a roller track  43  mounted along a side of the vehicle. Sliding vehicle doors typically employ three different sets of roller bracket/roller tracks with upper and lower roller brackets attached to the front edge of the sliding door and a center roller bracket connected to the rear edge of the sliding door. A set of rollers  44  on roller bracket  42  support door  40  and traverse roller track  43  between the closed position and a fully open position. The present invention can be utilized to provide end-damping and an easy-reach return function as follows. A bumper  45  carried by roller bracket  42  contacts a bumper link  46  of a return device  47  mounted at the end of track  43 . When bumper  45  contacts bumper link  46 , door  40  may be further pushed so that bumper link  46  is retracted within device  47  until sliding door  40  reaches its fully open position. Device  47  provides damping and energy absorption to slow the travel of sliding door  40  as previously described. In order to assist vehicle occupants in the effort to reach sliding door  40  in order to close it after having entered the vehicle, bumper link  46  returns to its extended or easy-reach position thereby moving sliding door  40  in the closing direction in a slow, controlled manner. 
         [0027]    A first embodiment of door return device  47  for providing end-damping and easy-reach automatic return without permanent connection to the door is shown in  FIG. 9 . A housing  50  contains a working fluid and an end-damping piston  51 . A return spring  52  is shown as a compression spring which is located between piston  51  and a back longitudinal wall  53  of housing  50 . An end-seal  54  receives link  46  to maintain alignment of link  46  and to prevent escape of the working fluid. Damping is controlled by a passage  55  through piston  51  and/or a tapered groove  56  in housing  50  as previously described. A soft, rubber bumper  57  may be mounted to the end of link  46  to avoid any displeasing sound or shock when impacting the roller bracket. Since return spring  52  acts as a compression spring, it can be placed between piston  51  and end wall  53  without needing any fastening connections. 
         [0028]    An alternative embodiment shown in  FIG. 10  utilizes an extension spring. Thus, housing  60  receives an end-damping piston  61  fixably mounted to link  46 . Extension spring  62  is fixably connected to piston  61  at one end and at its other end to an anchor point proximate an end seal  63 . The connection can be provided by an adhesive applied to end seal  63 , or spring  62  can be joined to housing  60  using an adhesive or other mechanical mounting. Damping during the retraction of link  46  into housing  60  is provided by a passage  64  in piston  61  and/or a tapered groove  65 . The energy absorption is also supplemented by extension of spring  62 . When the door is released and no longer forced against link  46 , extension spring  62  returns to its unloaded state shown in  FIG. 10  to push the door back to its easy-reach position. 
         [0029]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.