Abstract:
The present invention provides a drive mechanism for a vehicle lift gate. The drive mechanism includes a housing including a first end securable to a vehicle frame and an opposite second end securable to a lift gate. The drive mechanism further includes a spring disposed for movement within the housing along the axis between the first and second ends and biasing the first end axially relative to the second end. A damper extends around the housing for absorbing energy released by rapid axial movement of the spring relative to the housing.

Description:
FIELD OF THE INVENTION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/138,805, filed Mar. 26, 2015 and U.S. Provisional Application No. 62/142,233, filed Apr. 2, 2015. 
         [0002]    The present invention relates to spring-loaded mechanisms, particularly spring-loaded mechanisms used in vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Spring-loaded mechanisms, such as spring-loaded actuators and spring-loaded dampers used in vehicles, often have assembly defects or become damaged during use. If a spring-loaded mechanism is damaged severely enough, the spring on the spring-loaded mechanism may extend freely or with only minor resistance, allowing the spring to quickly extend in one or more directions and cause unintended damage (e.g., to the vehicle or to people nearby). 
       SUMMARY OF THE INVENTION 
       [0004]    According to one construction, the present invention provides a spring-loaded mechanism that includes an outer body, a spring disposed inside the body, the spring extending along an axis, and a safety mechanism disposed either inside or outside of the body that inhibits movement of the spring. 
         [0005]    Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a side view of a spring-loaded mechanism according to one construction. 
           [0007]      FIG. 2  is a partially transparent side view of the spring-loaded mechanism of  FIG. 1 , illustrating an interior spring and a safety mechanism disposed radially outwardly of the spring. 
           [0008]      FIG. 3  is a perspective view of the spring-loaded mechanism of  FIG. 1 . 
           [0009]      FIG. 4  is a side, cross-sectional view of a spring-loaded mechanism according to another construction, including a safety device disposed radially inwardly of a spring. 
           [0010]      FIG. 5  is a perspective, cross-sectional view of the spring-loaded mechanism of  FIG. 4 . 
           [0011]      FIGS. 6 and 7  are perspective views of the spring-loaded mechanism according to  FIGS. 4 and 5 , both with and without a safety device disposed radially outwardly of the spring. 
           [0012]      FIGS. 8 and 9  are perspective views of the spring-loaded mechanism according to  FIGS. 4-7 , both with and without another construction of a safety device disposed radially outwardly of the spring. 
           [0013]      FIGS. 10 and 11  are side and cross-sectional views of the spring-loaded mechanism according to claims  1 - 3 , illustrating use of the safety mechanism of  FIGS. 8 and 9 . 
           [0014]      FIGS. 12-14  are cross-sectional views of the spring-loaded mechanism according to  FIGS. 4 and 5 , with another construction of a safety device disposed radially inwardly of the spring. 
           [0015]      FIG. 15  is a cross-sectional view of the spring-loaded mechanism according to  FIGS. 4 and 5 , with the safety device from  FIGS. 12-14 . 
       
    
    
       [0016]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
       DETAILED DESCRIPTION 
       [0017]      FIGS. 1-3  illustrate a spring-loaded mechanism  10 . The spring-loaded mechanism  10  is a spring-loaded actuator or spring-loaded damper for use in a vehicle (e.g., a spring assist assembly for a power liftgate), although other constructions include different types of spring-loaded mechanisms for vehicle or non-vehicle use. 
         [0018]    The spring-loaded mechanism  10  includes a first end  14 , a second, opposite end  18 , and an axis  22  extending between the first and second ends  14 ,  18 . The spring-loaded mechanism  10  is generally cylindrical, although other constructions include different shapes. The spring-loaded mechanism  10  includes an outer body  26  and a spring  30  ( FIG. 2 ) disposed within the outer body  26 . In the illustrated construction the spring  30  is a wound spring (e.g., compression or tension spring) that is wound about the axis  22  and extends between the first end  14  and the second end  18 . The spring  30  provide an actuating and/or dampening force within the spring-loaded mechanism  30 , causing the first end  14  to move or be biased axially relative to the second end  18 . 
         [0019]    With continued reference to  FIGS. 1-3 , the spring-loaded mechanism  10  includes a first end cap  34  disposed at the first end  14  and a second end cap  38  disposed at the second end  18 . In some constructions at least one of the end caps  34 ,  38  is removably coupled to the outer body  26 . 
         [0020]    The spring-loaded mechanism  10  further includes a safety mechanism  42  that absorbs at least a portion of the energy of the spring  30  in the event that a portion or all of the spring  30  rapidly moves (e.g., radially outwardly from axis  22 , radially inwardly toward the axis  22 , or axially out or in along the axis  22 ) and/or breaks through the outer body  26 . Such movement can be due for example to the spring  130  breaking or having improper manufacturer specifications, or to other events. In the illustrated construction the safety mechanism  42  includes a first connection structure  44  ( FIG. 2 ) and a second connection structure  46  both disposed on the first end cap  34 , and a third connection structure  50  and a fourth connection structure  54  both disposed on the second end cap  38 . The connection structures  44 ,  46 ,  50 ,  54  are projections that extend axially inwardly from the first and second end caps  34 ,  38 . 
         [0021]    The safety mechanism  42  further includes a first cable  58  coupled to both the first connection structure  44  and the third connection structure  50 , and a second cable  62  coupled to both the second connection structure  46  and the fourth connection structure  54 . In some constructions the cables  58 ,  62  are releasably coupled to the connection structures  44 ,  46 ,  50 , and  54 , such that they may be removed or replaced as desired. In some constructions ends of each of the cables  58 ,  62  are coupled to the connection structures  44 ,  46 ,  50 ,  54  via frictional fit, welding, adhesion, fasteners, or are formed integrally as one piece with the connection structures  44 ,  46 ,  50 ,  54 . In the illustrated construction each of the cables  58 ,  62  is made of a fiber (e.g., woven) material that has a stretch capability that will allow it to absorb the impact energy of the spring  30 . 
         [0022]    With continued reference to  FIGS. 1-3 , in the illustrated construction the first and second cables  58 ,  62  wrap helically about the outer body  22  and the axis  22  and act as tethers to prevent or inhibit the moving (e.g., expanding) spring  30 , outer body  22 , or any other structure from damaging nearby components or people. In other constructions only a single, helically wound cable is used, or more than two helically wound cables are used. In some constructions at least a portion of each of the cables  58 ,  62  is elastic, such that when a portion of the spring  30  moves (e.g., radially outwardly or along the axis  22 ) the cables  58 ,  62  flex to a limited extent, or within a limited range, to slow down and absorb the energy of the rapidly moving spring  30 . 
         [0023]      FIGS. 4 and 5  illustrate another spring-loaded mechanism  110 . The spring-loaded mechanism  110  is a spring-loaded actuator or spring-loaded damper for use in a vehicle (e.g., in a motor assembly for a power liftgate), although other constructions include different types of spring-loaded mechanisms. 
         [0024]    The spring-loaded mechanism  110  includes a first end  114 , a second, opposite end  118 , and an axis  122  extending between the first and second ends  114 ,  118 . The spring-loaded mechanism  110  is generally cylindrical, although other constructions include different shapes. The spring-loaded mechanism  110  includes an outer body  126  (coupled to a motor  127  in the illustrated construction), an inner body  128  with an end fitting  129 , and a spring  130  disposed at least partially within the outer body  126  and over at least a portion of the inner body  128 . In the illustrated construction the spring  30  is a wound spring (e.g., compression or tension spring) that is wound about the axis  122  and extends between the first end  114  and the second end  118 . The spring  130  provide an actuating and/or dampening force within the spring-loaded mechanism  110  (e.g., to cause the inner body  128  to move and/or be biased axially toward a position relative to the outer body  126 ). 
         [0025]    With continued reference to  FIGS. 4 and 5 , the spring-loaded mechanism  110  includes a safety mechanism  142  that absorbs at least a portion of the energy of the spring  130  in the event that a portion or all of the spring  130  rapidly moves (e.g., radially inwardly toward the axis  122 , radially outwardly away from the axis, or in or out along the axis  122 ). In some constructions movement occurs due to the spring-loaded mechanism  110  being crushed or compacted (e.g., in the event of a power liftgate failure, vehicle crash, or other event). In the illustrated construction the safety mechanism  142  includes a first connection structure  144  and a second connection structure  146  both disposed on the outer body  126 , and a third connection structure  150  and a fourth connection structure  154  both disposed on the inner body  128 . 
         [0026]    The safety mechanism  142  further includes a first cable  158  coupled to both the first connection structure  144  and the third connection structure  150 , and a second cable  162  coupled to both the second connection structure  146  and the fourth connection structure  154 . In the illustrated construction each of the cables  158 ,  162  is made of a fiber (e.g., woven) material that has a stretch capability that will allow it to absorb the impact energy of the spring  130 . 
         [0027]    In some constructions the cables  158 ,  162  are releasably coupled to the connection structures  144 ,  146 ,  150 , and  154 , such that they may be removed or replaced as desired. In the illustrated construction the connection structures  144 ,  146 ,  150 ,  154  include walls of the outer and inner bodies  126 ,  128  that help to form openings or passages to receive and secure ends of the cables  158 ,  162 . In some constructions ends of each of the cables  158 ,  162  are coupled to the connection structures  144 ,  146 ,  150 ,  154  via frictional fit, welding, adhesion, fasteners, or are formed integrally as one piece with the connection structures  144 ,  146 ,  150 ,  154 . 
         [0028]    With continued reference to  FIGS. 4 and 5 , in the illustrated construction the first and second cables  158 ,  162  extend generally linearly along a direction parallel to the axis  122  and act as tethers (e.g., in some constructions helping to prevent or inhibit the spring  130  from damaging nearby components or people and from damaging interior components of the spring-loaded mechanism  110 ). In other constructions only a single cable is used, or more than two cables are used. In some constructions at least a portion of each of the cables  158 ,  162  is elastic, such that when a portion of the spring  130  rapidly moves due to component failure the cables  158 ,  162  flex to a limited extent, or within a limited range, to slow down and absorb the energy of the moving spring  130 . 
         [0029]      FIGS. 6 and 7  illustrate the same spring-loaded mechanism  110  from  FIGS. 4 and 5 , with the exception that the spring-loaded mechanism  110  includes a safety mechanism  242  ( FIG. 7 ) that absorbs at least a portion of the energy of the spring  130  in the event that a portion or all of the spring  130  rapidly moves (e.g., radially outwardly away from the axis  122 , radially inwardly toward the axis  22 , or out or in along the axis  22 ). In the illustrated construction the safety mechanism  242  includes a sock  244  that fits over the outer body  126  as well as at least a portion of the spring  130 , and extends between the first and second ends,  114 ,  118 . In the illustrated construction the sock  244  is made of multiple layers of fiber (e.g., woven) material that each have stretch capabilities that allow them to absorb the impact energy of the spring  130 . The multiple layers provide redundant protection in case one layer tears. In some constructions the spring-loaded mechanism  110  includes only the safety mechanism  242 , and not the safety mechanism  142  illustrated in  FIGS. 4 and 5 . 
         [0030]    With continued reference to  FIGS. 6 and 7 , in some constructions at least a portion of the sock  244  is elastic, such that if a portion of the spring  30  expands or otherwise moves radially outwardly the sock  244  flexes radially outwardly to a limited extent, or within a limited range, to slow down and absorb the energy of the expanding spring  130 . In the illustrated construction the sock  244  includes a first end  248  and a second, opposite end  252 . At least one of the first and second ends  248 ,  252  is sewn in (e.g., extends radially inwardly relative to the rest of the sock  244 ) to help further contain the spring  130  and prevent or inhibit the spring from expanding outwardly (either radially or axially). For example, in the illustrated construction the second end  252  is sewn in to provide an opening  253  through which the end fitting  129  protrudes. 
         [0031]      FIGS. 8 and 9  again illustrate the same spring-loaded mechanism  110  from  FIGS. 4-7 , with the exception that the spring-loaded mechanism  110  includes an alternative safety mechanism  342  that absorbs at least a portion of the energy of the spring  130  in the event that a portion or all of the spring  130  rapidly moves (e.g., radially outwardly away from the axis  122  or along the axis  122 ). In the illustrated construction the safety mechanism  342  includes a sock  344 , similar to the sock  244 , that fits over the outer body  126  as well as at least a portion of the spring  130 , and extends between the first and second ends,  114 ,  118 . In the illustrated construction the sock  344  is made of multiple layers of fiber (e.g., woven) material that have stretch capabilities that will allow them to absorb the impact energy of the spring  130 . The multiple layers provide redundant protection in case one layer tears. In some constructions the spring-loaded mechanism  110  includes only the safety mechanism  342 , and not the safety mechanism  142  illustrated in  FIGS. 4 and 5 . In some constructions both safety mechanisms  142 ,  342  are used. 
         [0032]    With continued reference to  FIGS. 8 and 9 , in some constructions at least a portion of the sock  344  is elastic, such that when a portion of the spring  30  expands or otherwise moves radially outwardly the sock  344  flexes radially outwardly to a limited extent, or within a limited range, to slow down and absorb the energy of the expanding spring  30 . In the illustrated construction the sock  344  includes a first end  348  that is sewn in (e.g., extends radially inwardly relative to an adjacent portion of the sock  344 ) to help further contain the spring  130  and prevent or inhibit the spring from expanding outwardly (either radially or axially) to damage other components or people. In the illustrated construction the first end  348  is sewn in to provide an opening  353  through which the end fitting  129  protrudes. The sock  344  further includes a second, opposite end  352  that includes multiple flaps  354  (e.g., four flaps) that may be opened and closed. As illustrated in  FIG. 8 , the flaps  354  include ends  358  that function as hooks that are bent radially inwardly to help secure the sock  344  to the outer body  126 . In particular, the flaps  354  include openings  360  that hook over or secure to a part of the outer body  126  (e.g., to a single component, or to multiple components). 
         [0033]      FIGS. 12-14  illustrate the same spring-loaded mechanism  10  from  FIGS. 1-3 , with the exception that the spring-loaded mechanism  10  includes a different safety mechanism  442  ( FIG. 14 ) that absorbs at least a portion of the energy of the spring  30  in the event that a portion or all of the spring  30  rapidly moves (e.g., radially inwardly toward the axis  22 , radially outwardly away from the axis, or out or in along the axis  22 ). In the illustrated construction the safety mechanism  442  includes an outer safety tube  446  (e.g., metal), an inner safety tube  450  (e.g., metal) disposed radially inwardly of the outer safety tube  446 , and a compliant bushing  454  disposed radially between the outer safety tube  446  and the inner safety tube  450 . The inner safety tube  450  includes a set of radially protruding ribs  458 . 
         [0034]    In the event of component failure (e.g., when the spring-loaded mechanism  10  is crushed or when a component breaks), the spring-loaded mechanism  10  may extend (see  FIG. 13 , as compared to  FIG. 12 ) rapidly. If this occurs, the compliant bushing  454  will be deformed with a wedging action between the outer safety tube  446  and the inner safety tube  450 , absorbing some of the energy along an axial direction (e.g., in some constructions due at least partly to its shape, as seen for example in  FIG. 14  with the rectangular cross-sectional shape of the bushing  454  as compared with the angled end of the outer tube  446  adjacent the bushing  454 ). In some constructions the outer safety tube  446  and inner safety tube  450  themselves deform to absorb energy. In some constructions, for example in a side crush condition, the outer safety tube  446  will deflect and not allow the extension shown in  FIG. 13  due to a dent or deformation on the outer safety tube  446  running into or being blocked (axially) by the ribs  458  on the inner safety tube  450 . In some constructions, under a severe side crush the outer safety tube  446  and the inner safety tube  450  bend together and lock up the spring-loaded mechanism  10 , preventing the spring-loaded mechanism  10  from extending as shown in  FIG. 13 . Overall, the safety mechanism  442  (similar to the other safety mechanisms  42 ,  142 ,  242 , and  342 ) helps to absorb energy and decelerate the speed and energy of the spring  30 . 
         [0035]    While the safety mechanisms  42 ,  142 ,  242 ,  342 ,  442  are illustrated and described above specifically with respect to particular spring loaded mechanisms  10  and  110 , it is understood that each of the spring loaded mechanisms  10  and  110  (or other spring loaded mechanisms) can include one or more of each of the safety mechanisms  42 ,  142 ,  242 ,  342 ,  442  described above. For example,  FIGS. 10 and 11  illustrate the spring-loaded mechanism  10  of  FIGS. 1-3 , but with the safety mechanism  342  disposed thereon, including the flaps  354  which in this illustrated construction all extend over a single end piece  362 . Similarly,  FIG. 15  illustrates the safety mechanism  442  being used on the spring-loaded mechanism  110 . 
         [0036]    Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.