Abstract:
A hub and wheel assembly enabling the moving direction of wheels of a vehicle to be adjusted instantly as the exerted pushing force changes direction comprises a wheel mount having wheels mounted thereon, and a swivel base assembly mounted on stroller leg. Wheel mount may quickly assemble with and detach from swivel base assembly. A protrusion of wheel mount, inserted into swivel base assembly, includes a circumferential groove having a cavity provided therein such that a spring-biased locking member may releasably engage with cavity for setting movement of wheels in a linear direction. Further, as a deflecting force is applied on the stroller locking member disengages with cavity for allowing wheels to move to left or right. Once the force is released, locking member will instantly return to its normal position to engage with cavity.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hub and wheel assembly, and more particularly to swivel-mounted wheel assemblies adapted for use on baby stroller or cart in which the moving direction of wheels can be adjusted instantly as the exerted pushing force changes direction. 
     BACKGROUND OF THE INVENTION 
     Typically, most light-load vehicles such as strollers or carts have one or more wheels mounted on a bracket which pivotably mounted to frame of vehicle. As such, wheels can rotate freely for changing moving direction. However, such swivel-mounted wheeled vehicles tend to move irregularly in an uneven surface or a non-linear direction. As a result, a user must exert additional force on vehicle to overcome the irregularity to keep it moving in a linear direction. Further, such vehicle is not able to move in a linear direction after a forward pushing force is released, i.e., it will wobble. Additionally, user may loosen the grasp of the vehicle due to collision with the other object. As a result, vehicle may wobble and even fall. This may hurt the vehicle passenger. 
     A solution to the above problems associated with swivel-mounted wheel assembly is to either set the moving of wheel in a predetermined direction or let wheel swivel such as those disclosed in U.S. Pat. Nos. 5,103,530, 5,234,226, and 5,581,843. These patents generally disclose a hub and wheel arrangement having a cap pivotally secured to a swivel base assembly in an engagement configuration or cap disengaged with swivel base assembly for permitting wheels to move in a fixed direction or to rotate freely. However, such engagement or disengagement is done by manually manipulating cap. This manipulation is inconvenient. 
     SUMMARY OF THE INVENTION 
     It is thus an object of the present invention to provide a hub and wheel assembly with automatic moving direction adjustment mechanism in which the moving direction of wheels of a vehicle can be adjusted instantly as the exerted pushing force changes direction. 
     The advantages of the present invention are realized by providing a wheel mount having wheels mounted thereon, and a swivel base assembly mounted on stroller leg in which wheel mount is able to quickly assemble with and detach from swivel base assembly. A protrusion of wheel mount, inserted into swivel base assembly, includes a circumferential groove having a cavity provided therein such that a spring-biased locking member may releasably engage with cavity for setting movement of wheels in a predetermined linear direction. Further, as a left or right force is applied on the stroller the locking member disengages with cavity for allowing wheels to move to left or right. Once the force is released or a forward force is applied subsequently, the locking member will instantly return to its normal position to engage with cavity again. 
     The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded sectional view of a first embodiment of the present invention showing swivel base assembly, wheel mount, and lever; 
     FIG. 2 is a sectional view of FIG. 1 with wheels assembled thereon; 
     FIG. 3A is a top sectional view of FIG. 2 showing the engagement of locking member with cavity in a linear moving direction; 
     FIG. 3B is a top sectional view of FIG. 2 showing locking member disengaged with cavity when a deflecting force is applied on the stroller; 
     FIG. 4 is an exploded sectional view of a second embodiment of the present invention showing swivel base assembly and wheel mount; 
     FIG. 5 is a sectional view of FIG. 4 with wheels assembled thereon; 
     FIG. 6A is a top sectional view of FIG. 5 showing the engagement of locking member with cavity in a linear moving direction; 
     FIG. 6B is a top sectional view of FIG. 5 showing locking member disengaged with cavity when a deflecting force is applied on the stroller; 
     FIG. 7 is a sectional view of a third embodiment of the present invention; 
     FIG. 8 is a top sectional view of FIG. 7 showing the engagement of locking member with cavity in linear moving direction; and 
     FIG. 9 is sectional view showing another configuration of engaging swivel base assembly with wheel mount. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The First Embodiment 
     Referring to FIGS. 1-2, a hub and wheel assembly of the first embodiment of the present invention comprises a swivel base assembly  10 , a wheel mount  20  and wheels  30 . Swivel base assembly  10  has a leg housing  101  and a base  102 . Leg housing  101  has a first receiving space  1011  with opening upward and an aperture  1012 . As such, aperture  1012  receiving a screw or a suitable alternative (not shown) may threadedly secure leg housing  101  to a stroller leg (not shown). Base  102  has a second receiving space  1021  with opening downward, an upper aperture  1022  and a lower aperture  1023  both penetrated through base  102  to reach second receiving space  1021 , and a pivot point  1024 . A locking member  1025  generally of cylindrical shape is movable within upper aperture  1022  and protruded into second receiving space  1021  with its round head portion. 
     A lever  40  comprises an upper protrusion  401 , a lower protrusion  402 , and a lever pivot  403 . Lever pivot  403  is mounted on pivot point  1024  of base  102  and thus lever  40  can be pivotally about pivot point  1024  in a predetermined range. Upper protrusion  401  and lower protrusion  402  of lever  40  may be received in upper aperture  1022  and lower protrusion  1023  respectively. A spring  1026  is received in locking member  1025  with one end urged against bottom of locking member  1025  and the other distal end put on upper protrusion  401 . Locking member  1025  is pushed to partly insert into second receiving space  1021  and upper protrusion  401  is pushed away from base  102  both by the compression of spring  1026 . Accordingly, lower protrusion  402  of lever  40  is penetrated through lower aperture  1023  to reach second receiving space  1021 . To the contrary, lower protrusion  402  will clear second receiving space  1021  if a pushing force toward base  102  is applied on upper protrusion  401  of lever  40 . 
     Wheel mount  20  comprises a protrusion  201  for inserting into and free turning within second receiving space  1021  of swivel base assembly  10 , and an axle  202  for allowing wheels  30  rotatably mounted thereon. Alternatively, a shock absorber (not shown) is mounted between axle  202  and each wheel  30  for providing a smooth ride over irregular surface conditions. Protrusion  201  has an upper circumferential groove  2011  and a lower recessed portion  2012  disposed corresponding to upper aperture  1022  and lower aperture  1023  of swivel base assembly  10  respectively. Locking member  1025  of swivel base assembly  10  inserts into circumferential groove  2011  and lower protrusion  402  of lever  40  snaps into recessed portion  2012  of protrusion  201  respectively when protrusion  201  of wheel mount  20  is inserted into second receiving space  1021  of swivel base assembly  10 . In other words, base assembly  10  is swivel-mounted on wheel mount  20  so as to enable wheels  30  to rotate freely relative to base assembly  10 . As stated above, lower protrusion  402  will clear second receiving space  1021  of base assembly  10  if a pushing force toward base  102  is applied on upper protrusion  401  of lever  40 . As such, wheel mount  20  will disengage with swivel base assembly  10  by manually pulling down wheel mount  20 . In view of foregoing, it is seen that wheel mount  20  and swivel base assembly  10  can be assembled or detached in a quick manner. 
     Referring to FIGS. 3A-3B, circumferential groove  2011  has two ridges  2013  and a cavity  2014  formed therebetween. Cavity  2014  is disposed parallel to the radial direction of wheels  30 . In a linear moving condition of wheels  30 , locking member  1025  is secured in cavity  2014  of circumferential groove  2011 . As such, the moving direction of wheel mount  20  is fixed and accordingly the moving direction of wheels  30  is fixed (see FIG.  3 A), i.e., cavity  2014  is aligned with the wheel mount  20  and wheels  30  in the moving direction. 
     As stated above, locking member  1025  is spring-biased and has a round head and thus a left or right force is applied on the stroller the force will impart to wheel mount  20  to bias locking member  1025  inward such that locking member  1025  disengages with cavity  2014  to move over ridge  2013  and abutted thereon for allowing wheel mount  20  as well as wheels  30  to move to left or right. Once the force is released or a forward force is applied subsequently, locking member  1025  will instantly return to its normal position to engage with cavity  1014 . As such, wheels  30  move in a linear direction again. In order to more precisely control the engagement/disengagement of locking member  1025  with cavity  2014 , preferably, circumferential groove  2011  has two pairs of two ridges  2013  and a cavity  2014  in which two cavities  2014  are separated by 180° each other. 
     Further, a wheel lock lever  50  is optionally provided in wheel mount  20  for permitting a user to manually restrict rotation of wheel mount  20  of the stroller in a locked condition. Alternatively, release wheel lock lever  50  to let wheel mount  20  freely rotate. 
     The Second Embodiment 
     Referring to FIGS. 4-5, a hub and wheel assembly of the second embodiment of the present invention comprises a swivel base assembly  10 ′, a wheel mount  20 ′ and wheels  30 ′. Swivel base assembly  10 ′ has a leg housing  101 ′ and a base  102 ′. Leg housing  101 ′ has a first receiving space  1011 ′ with opening upward and an aperture  1012 ′. As such, aperture  1012 ′ receiving a screw or a suitable alternative (not shown) may threadedly secure leg housing  101 ′ to a stroller leg (not shown). Base  102 ′ has a second receiving space  1021 ′ with opening downward. An upper circumferential groove  1027 ′ is provided inside second receiving space  1021 ′. An aperture  1028 ′ is provided to penetrate through base  102 ′ to reach second receiving space  1021 ′. A head portion of a spring-biased locking member  1029 ′ served as a quick coupling and detaching means for swivel base assembly  10 ′ and wheel mount  20 ′ is penetrated through aperture  1028 ′ in a locked position. 
     Wheel mount  20 ′ comprises a protrusion  201 ′ for inserting into and free turning within second receiving space  1021 ′ of swivel base assembly  10 ′, and an axle  202 ′ for allowing a wheel  30 ′ rotatably mounted thereon. Protrusion  201 ′ has an upper receiving space  2016 ′ and a lower recessed portion  2019 ′ disposed corresponding to locking member  1027 ′ and aperture  1028 ′ of swivel base assembly  10 ′ respectively. A locking member  2017 ′ and a spring  2018 ′ are received within receiving space  2016 ′ in which spring  2018 ′ is biased between locking member  2017 ′ and the bottom of receiving space  2016 ′. As such, locking member  2017 ′ is movable in receiving space  2016 ′ to cause its round head portion to insert into circumferential groove  1027 ′ of swivel base assembly  10 ′ when swivel base assembly  10 ′ is mounted on wheel mount  20 ′. 
     As to the disengagement of wheel mount  20 ′ and swivel base assembly  10 ′, pull spring-biased locking member  1029 ′ outwardly to clear recessed portion  2019 ′ of wheel mount  20 ′. Thereafter, locking member  2017 ′ clears circumferential groove  1027 ′ if a pull down force is applied on wheel mount  20 ′ so as to disengage wheel mount  20 ′ with swivel base assembly  10 ′. In view of foregoing, it is seen that wheel mount  20 ′ and swivel base assembly  10 ′ can be assembled or detached in a quick manner by means of manipulating spring-biased locking member  1029 ′. 
     Referring to FIGS. 6A-6B, circumferential groove  1027 ′ of swivel base assembly  10 ′ has two ridges  103 ′ and a cavity  104 ′ formed therebetween. Cavity  104 ′ is disposed parallel to the radial direction of wheels  30 ′. In a linear moving condition of wheels  30 ′, locking member  2017 ′ is secured in cavity  104 ′ of circumferential groove  1027 ′. As such, the moving direction of wheel mount  20 ′ is fixed and accordingly the moving direction of wheels  30 ′ is fixed (see FIG.  6 A), i.e., cavity  104 ′ is aligned with the wheel mount  20 ′ and wheels  30 ′ in the moving direction. 
     As stated above, locking member  2017 ′ is spring-biased and has a round head and thus a left or right force is applied on the stroller the force will impart to wheel mount  20 ′ to bias locking member  2017 ′ inward such that locking member  2017 ′ disengages with cavity  104 ′ to move over ridge  103 ′ and abutted thereon for allowing wheel mount  20 ′ as well as wheels  30 ′ to move to left or right. Once the force is released or a forward force is applied subsequently, locking member  2017 ′ will instantly return to its normal position to engage with cavity  104 ′. As such, wheels  30 ′ move in a linear direction again. In order to more precisely control the engagement/disengagement of locking member  2017 ′ with cavity  104 ′, preferably, circumferential groove  1027 ′ has two pairs of two ridges  103 ′ and a cavity  104 ′ in which two cavity  104 ′ are separated by 180° each other. 
     Further, a wheel lock lever  50 ′ is optionally provided in wheel mount  20 ′ for permitting the user to manually restrict rotation of wheel mount  20 ′ of the stroller in a locked condition. Alternatively, release wheel lock lever  50 ′ to let wheel mount  20 ′ freely rotate. 
     The Third Embodiment 
     The turning of wheels in the first and second embodiments are controlled by a radial coupling mechanism of locking member and cavity, while the turning of wheels in the third embodiment is controlled by an axial coupling mechanism of locking member and cavity. 
     Referring to FIG. 7, a hub and wheel assembly of the third embodiment of the present invention comprises a swivel base assembly  10 ″, a wheel mount  20 ″ and wheels  30 ″. Swivel base assembly  10 ″ has a leg housing  101 ″ and a base  102 ″. Leg housing  101 ″ has a first receiving space  1011 ″ with opening upward and an aperture  1012 ″. As such, aperture  1012 ″ receiving a screw or a suitable alternative (not shown) may threadedly secure leg housing  101 ″ to a stroller leg (not shown). Base  102 ″ has a second receiving space  1021 ″ with opening downward. A circumferential groove  1027 ″ is provided around the bottom of base  102 ″. 
     Wheel mount  20 ″ comprises a protrusion  201 ″ for inserting into and free turning within second receiving space  1021 ″ of swivel base assembly  10 ″, and an axle  202 ″ for allowing a wheel  30 ″ rotatably mounted thereon. Wheel mount  20 ″ has a receiving space  2016 ″ disposed corresponding to groove  1027 ″ of swivel base assembly  10 ″. A locking member  2017 ″ and a spring  2018 ″ are received within receiving space  2016 ″ in which spring  2018 ″ is biased between locking member  2017 ″ and the bottom of receiving space  2016 ″. As such, locking member  2017 ″ is movable in receiving space  2016 ″ to cause its round head portion to insert into circumferential groove  1027 ″ of swivel base assembly  10 ″ when swivel base assembly  10 ″ is mounted on wheel mount  20 ″. 
     Referring to FIG. 8, circumferential groove  1027 ″ of swivel base assembly  10 ″ has two ridges  103 ″ and a cavity  104 ″ formed therebetween. Cavity  104 ″ is disposed parallel to the radial direction of wheels  30 ″. In a linear moving condition of wheels  30 ″, locking member  1025 ″ is secured in cavity  104 ″ of circumferential groove  1027 ″. As such, the moving direction of wheel mount  20 ″ is fixed and accordingly the moving direction of wheels  30 ″ is fixed, i.e., cavity  104 ″ is aligned with the wheel mount  20 ″ and wheels  30 ″ in the moving direction. 
     As stated above, locking member  2017 ″ is spring-biased and has a round head and thus a left or right force is applied on the stroller the force will impart to wheel mount  20 ″ to bias locking member  2017 ″ inward such that locking member  2017 ″ disengages with cavity  104 ″ to move over ridge  103 ″ and abutted thereon for allowing wheel mount  20 ″ as well as wheels  30 ″ to move to left or right. Once the force is released or a forward force is applied subsequently, locking member  2017 ″ will instantly return to its normal position to engage with cavity  104 ″. As such, wheels  30 ″ move in a linear direction again. In order to more precisely control the engagement/disengagement of locking member  2017 ″ with cavity  104 ″, preferably, circumferential groove  1027 ″ has two pairs of two ridges  103 ″ and a cavity  104 ″ in which two cavity  104 ″ are separated by  1800  each other. 
     Further, a wheel lock lever  50 ″ is optionally provided in wheel mount  20 ″ for permitting the user to manually restrict rotation of wheel mount  20 ″ of the stroller in a locked condition. Alternatively, release wheel lock lever  50 ″ to let wheel mount  20 ″ freely rotate. 
     Lower protrusion  402  of lever  40  of first embodiment and spring-biased locking member  1029 ′ of second embodiment may be omitted by providing a receiving space  203  for receiving a connecting rod  60  therein which further firmly secured by a pin  70  penetrating through protrusion  201  and connecting rod  60  as shown in FIG.  9 . Again, base assembly  10  is swivel-mounted on wheel mount  20  for allowing the wheel assembly to rotate freely. 
     While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.