Abstract:
A foldable bicycle provided with a frame, the frame comprising a first arm having a rear end to which a rear wheel is linked, a fork with handlebar to which a front wheel is linked, a bar connecting a front end of the first arm to the fork and hinged to the first arm and a post supporting a saddle and hinged to the first arm. The first arm, the bar and the post are interconnected by transmission elements for simultaneously rotating about the axes between an operative configuration and a carrying configuration. The transmission elements comprise a first engagement angular sector rotatably coupled with said post via first linkages, and a second engagement angular sector in rotary engagement with the first engagement angular sector and rotatably coupled with the bar via second linkages.

Description:
[0001]    The present invention relates to a foldable bicycle with spokeless wheels. 
       BACKGROUND OF THE INVENTION 
       [0002]    Foldable bicycles have been known for many years, e.g., the bicycle described in GB 2,287,438, in which the frame has a middle articulation joint which allows it to be folded by 180° about a vertical axis, after releasing a locking mechanism, in order to halve the longitudinal size of the bicycle and allow the latter to be eaily carried on a vehicle. 
         [0003]    Other foldable bicycle are known, e.g., from DE 10 2007 013158 A1, wherein the frame consists of various frame parts hinged to one another about transverse axes and are interconnected for simultaneously rotating from an operative configuration to a folded, carrying configuration. 
         [0004]    The above-described foldable bicycles have the drawback that the frame and the wheels are relatively small-sized, because they are designed to obtain a very compact folded configuration, to the detriment of the driving comfort and performance, which, in fact, are very limited, especially on uneven roads. 
         [0005]    Moreover, even in their folded configuration, the above bicycles are heavy-weighted and sizable, so that they are not suitable to be carried by hand. 
         [0006]    In the attempt of improving the driving comfort, WO/2006/131742 describes a foldable bicycle provided with standard-sized wheels. The frame has a front end and a rear end which are foldable about respective vertical axes, to which ends the two wheels are hinged. In particular, both the wheels of the bycicle of the above document are spokeless and are supported by a set of bearings engaged between the wheel and a respective guide attached to the frame. The lack of spokes allows some mechanical parts, such as the pedals, to be stored in the inner area of the wheels when the bicycle is folded, in order to reduce its overall size. 
         [0007]    The above-mentioned bicycle, of course, is handier to be driven than the bicycles with small-sized wheels such as the one described in the above-cited document, GB 2,287,438, and the folding system makes it easier to carry the bicycle on a vehicle. However, the bicycle, even when folded, is yet too cumbersome to be carried by hand. 
         [0008]    Furthermore, the above folding system having a frame provided with two articulation joints may be difficult to handle for the cyclist, who must handle the various parts of the frame while the latter is laying in precarious balance on the two wheels. 
         [0009]    Nevertheless, although the use spokeless wheels is convenient because it reduces the weight of the bicycle, improves the aerodynamic properties, and prevents the risk of undesired locks caused by the intrusion of rigid bodies and/or limbs of the human body between the spokes, however the wheel-supporting system of the above document is liable to jamming in case of dust, sand or stones slipping into the bearings. 
         [0010]    Other systems are known for connecting spokeless wheels to the frame of a bicycle, such as those described in U.S. Pat. No. 5,419,619 and U.S. Pat. No. 5,248,019, which provide for the use of an inner, stationary rim integral with the frame and an outer, rotary rim, with a crown of balls engaged between the rims. In other systems, such as the one described in U.S. Pat. No. 917,967, the wheel is locked by three rollers spaced from one another by two adjustable members. 
         [0011]    With the above-cited systems, the advantages resulting from using spokeless wheels are limited, because the structure that connects the wheel to the frame is heavy and obstructs a considerable fraction of the inner area of the wheel. 
       SUMMARY OF THE INVENTION 
       [0012]    Therefore, it is a main object of this invention to provide a foldable bicycle which, in its operative configuration, has a standard size likewise a traditional city bicycle, but can be converted to a folded, carrying configuration which is considerably smaller in size than the known foldable bicycles, in order to allow the bicycle to be easily carried by hand or on a shoulder. 
         [0013]    It is another object of the invention to provide a bicycle provided with a handy, practical folding system, which minimizes the number of actions and operations required for converting the bicycle from its operative configuration to its folded configuration, and vice versa. 
         [0014]    In is a further object of the invention to provide a bicycle which, even though provided with spokeless wheels, is not subjected to jamming and has a reliable, lightweight system for connecting the wheels to the frame. 
         [0015]    The above object and other advantages, which will better appear from the following description, are achieved by the foldable bicycle having the features recited in claim  1 , while the dependent claims state other advantageous, though secondary features, of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention will be now described in more detail with reference to a preferred, non-exclusive embodiment, shown by way of non limiting example in the attached drawings, wherein: 
           [0017]      FIG. 1  is a view in side elevation of the bicycle according to the invention; 
           [0018]      FIG. 2  is another view in side elevation of the bicycle according to the invention, from the opposite side with respect to  FIG. 1 ; 
           [0019]      FIG. 3  is an exploded, perspective view of the bicycle according to the invention; 
           [0020]      FIG. 4  is a view in axial cross-section to an enlarged scale of a detail of  FIG. 1  along plane IV-IV; 
           [0021]      FIG. 5  is a view in axial cross-section to an enlarged scale of a detail of  FIG. 1  along plane V-V; 
           [0022]      FIG. 6  is a view in axial cross-section to an enlarged scale of a detail of  FIG. 1  along plane VI-VI; 
           [0023]      FIG. 7  is a view in axial cross-section to an enlarged scale of a detail of  FIG. 1  along plane VII-VII; 
           [0024]      FIGS. 8 to 13  show the bicycle according to the invention in six consecutive steps of convertion from an operative configuration to a folded, carrying configuration; 
           [0025]      FIG. 14  is a view similar to  FIG. 9  to an enlarged scale; 
           [0026]      FIG. 15  is a perspective view of the frame of the bicycle in the folded, carrying configuration; 
           [0027]      FIG. 16  shows the bicycle folded in its carrying configuration, while carried in a bag by a generic user. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    With reference to the above Figures, a bicycle  10  is provided with a frame supported on a rear wheel  12  and a front wheel  14 . Each of the wheels comprises an annular frame, usually called spokeless rim  12   a ,  14   a , which supports a conventional tubular tire  12   b ,  14   b  made of a synthetic material. Tubular tire  12   b ,  14   b  may be both of the type provided with an inner tube and of the tubeless type. The profile of rim  12   a ,  14   a  will be described in more detail later on. 
         [0029]    The frame comprises a bar  15  splitted in two side-by-side, half-bars  16 ,  18  ( FIG. 3 ), which are arranged in mirror-like fashion with respect to the middle plane of bicycle  10 , and have an arched profile with its concavity facing downwards. A lower arm  20  and an upper arm  22  have their front ends  20   a ,  22   a  hinged to the rear ends  16   a ,  18   a  of half-bars  16 ,  18  about a first transverse axis X 1  parallel to the axis of rear wheel  12 . As shown in the Figures, arms  20 ,  22  project from their hinge axis in a scissor-like open fashion. Lower arm  20  and upper arm  22  bear respective rear rollers, i.e., a lower roller  24  and an upper roller  26  respectively, at their rear ends  20   b ,  22   b , which engage the inner profile of rim  12   a  of rear wheel  12  at diametrally opposite positions. 
         [0030]    As shown in  FIGS. 4 ,  5 , the inner profile of rear rim  12   a  has a cylindrical middle portion  28  engaged by corresponding cylindrical middle sections  24   a ,  26   a  of lower roller  24  and upper roller  26  respectively, as well as two bevelled, opposite side walls  30 ′,  30 ″ which are laterally restrained between corresponding side edges  24   b ′,  24   b ″,  26   b ′,  26   b ″ of rear rollers  24 ,  26  having a complementary profile. Lower arm  20  also bears a stabilizing roller  32  at an intermediate position, which internally engages the rim of the rear wheel at third point in front of the other two rear rollers. 
         [0031]    Lower roller  24  is connected to a gear wheel  34 , which is rotatably coupled with a crown gear  35  of a driving assembly  36  provided with pedals  38  via a chain  40 . Driving assembly  36  is hinged to lower arm  20  about a second transverse axis X 2  ( FIG. 2 ). 
         [0032]    Having now particular reference to  FIGS. 1 and 2 , a saddle  42  is supported on the top of a post  44 , the lower end of which is received in a sleeve  46  which is transversely hinged to lower arm  20  about second axis X 2 . The axial position of post  44  in sleeve  46  is locked by a conventional locking mechanism (not shown). A first bush  48  is slidably fitted to post  44  and is connected to lower arm  20  via a connecting rod  50  ( FIG. 2 ). Connecting rod  50  has a lower end  50   a  hinged to lower arm  20  behind the hinge point of sleeve  46 , and an opposite, upper end  50   b  hinged to bush  48 . As shown in the Figures, the length of connecting rod  50  and the position of the various hinge points are preferably chosen in such a way that post  44  is sligthly inclined rearwards when the bicycle in its operative configuration, for the scopes which will be clarified later on. 
         [0033]    A contoured groove  52  acting as a guide is formed on the inner vertical surface of upper arm  22 . Groove  52  is engaged by a sliding pin  53 , integral with connecting rod  50 , which acts a slide. Groove  52  is shaped in such a way that, when post  44  is rotated towards the front end of the bicycle about hinge axis X 2  of sleeve  46  (i.e., clockwise direction in  FIG. 1 , counterclockwise direction in  FIG. 2 ), upper arm  22  rotates towards lower arm  20  (i.e., counterclockwise direction in  FIG. 1 , clockwise direction in  FIG. 2 ) by camming action of sliding pin  53  running through groove  52 . 
         [0034]    Preferably, as shown in detail in  FIG. 14 , the rear end of groove  52  extends beyond the point in which both lower roller  24  and upper roller  26  engage rear rim  12   a  without deforming it, with an interference portion  52   a  which terminates with a notch  52   b . Notch  52   b  is shaped in such a way that, once pin  53  has been forced into it, after running through interference portion  52   a  (during this step rim  21   a  of rear wheel is subjected to a slight elastic deformation), lower roller  24  and upper roller  26  come back to the position of  FIG. 2 , in which both of them engage rear rim  12   a  without deforming it. 
         [0035]    Upper arm  22  has a first sector gear  54  formed at its front end about its hinging axis X 1 , for the scopes which will be clarified later on. 
         [0036]    The front end of half-bars  16 ,  18  are connected, via a second sleeve  57 , to a fork  58  integral with a pole  59 , at the top of which a handlebar  60  is supported. Second sleeve  57  is hinged to the front ends  16   b ,  18   b  of half-bars  16 ,  18  about a third transverse axis X 3 . The lower end  59   a  of pole  59  is received within second sleeve  57 . A second bush  64  slidable along pole  59  above second sleeve  57  is connected to the rear ends of half bars  16 ,  18  via a lever  66 . Lever  66  has a rear end  66   a  hinged between the rear ends  16   a ,  18   a  of half-bars  16 ,  18 , about a third transverse axis X 4  ( FIG. 4 ) located close to, and in front of, the hinge axis X 1  about which half-bars  16 ,  18  are hinged to the rear arms. A front end  66   b  of lever  66  is hinged to second bush  64 . In particular, rear end  66   a  of lever  66  terminates with two projections  66   a ′,  66   a ″, each of which is hinged to the half-bar on the corresponding side. A second sector gear is formed on one of the projections,  66   a ″, about the hinge axis of the latter, which meshes with sector gear  54  of upper arm  22 . 
         [0037]    Fork  58  supports front wheel  14  via a pair of side-by-side, mirror-like jaws  68 ,  70 , which are interconnected by bridges  71   a ,  71   b  ( FIG. 3 ) and support two pairs of counterposed frustoconical rollers  72   a ,  72   b  and  74   a ,  74   b  arranged therebetween, which are advantageously spaced at an angle in the range 45° to 90°, preferably 70°, as well as an inner roller  76 . As shown in detail in  FIGS. 6 ,  7 , front rim  14   a  is shaped with a cylindrical middle portion  78  engaged by a corresponding, cylindrical middle section  76   a  of roller  76 , as well as two opposite, bevelled side walls  80 ′,  80 ″ which are laterally restrained between corresponding side edges  76   b ′,  76   b ″ of inner roller  76 , which have a complementary profile. Each pair of rollers  72   a ,  72   b  and  74   a ,  74   b  externally engages respective opposite bevelled walls  82 ′,  82 ″ of the outer profile of rim  14   a . Roller  76  is hinged to fork  58  about a removable pin  84  which passes through jaws  68 ,  70  ( FIG. 6 ). The jaws are also anchored to fork  58  via respective studs  86 ,  88 . 
         [0038]      FIG. 1  illustrates bicycle  10  in its operative configuration. When rear arms  20 ,  22  are open in a scissor-like fashion, both rear rollers  24 ,  26  and stabilizing roller  32  internally engage rim  12   a  of rear wheel  12 . In this configuration, sliding pin  53  restrainedly engages notch  52   b  ( FIG. 2 ) and, by effect of the inclination of post  44  towards the rear end of the bicycle, the weight of the cyclist (not shown) sitting on saddle  42  contributes in maintaining sliding pin  53  in that position. 
         [0039]    With particular reference to  FIGS. 8-13 , in order to convert the bicycle to its folded, carrying configuration, pin  84  ( FIG. 9 ) is removed, whereby roller  76  is unlocked and front wheel  14  is consequently set free. To remove rear wheel  12 , rear arms  20 ,  22  are slightly opened (with consequent, slight, elastic deformation of rear rim  12   a ) until pin  53  disengages notch  52   b  and engages groove  52  ( FIGS. 9 ,  14 ). Now that rear wheel  12  can be removed, post  44  supporting saddle  42  is rotated forwards, i.e., in the direction indicated by arrow A  1  in  FIG. 10 , so that upper arm  22  progressively rotates towards lower arm  20 , in the direction indicated by arrow A 2  in  FIG. 10 , by engagement of sliding pin  53  along groove  52 . 
         [0040]    The rotation of upper arm  22  causes lever  66  to simultaneously rotate in the opposite direction, i.e., in the direction indicated by arrow A 3  in  FIG. 10 , by meshing of first sector gear  54  with second sector gear  66   a ″. The rotation of lever  66  causes fork  58  and bar  15  to rotate in the same direction ( FIGS. 10 ,  11 ), by action of second bush  64  sliding along pole  59 , until the frame is completely folded to the compact configuration of  FIG. 12 . It should be noted that, when bar  15  is closed, jaws  68 ,  79 , which are free to rotate about the respective studs  86 ,  88 , are stored in the concave lower area defined by half-bars  16 ,  18 . In order to completely compact the frame to the folded configuration of  FIGS. 13 ,  15 , saddle  42  can be lowered by unlocking the locking mechanism (not shown) and making post  44  slide along sleeve  46 . 
         [0041]    As the person skilled in the art will immediately understand, the bicycle according to the invention has the advantages of both a traditional bicycle and a foldable bicycle, because, in use, it has a standard size, while, in its folded configuration, it is very compact. Using spokeless wheels allows the free area inside the rims to be used as a housing for the folded frame, so that the whole kit can be received in a bag S, which is shaped and sized ad hoc and can be carried either by hand or on a shoulder, as shown in  FIG. 16 . Alternatively, the frame and the wheels could be carried by different users. 
         [0042]    The above-described folding system is also practical and handy because, once removed the wheels, the various projecting parts of the frame, particularly rear arms  20 ,  22 , post  44  supporting saddle  42 , bar  15 , and fork  58  with pole  59  attached thereto which supports handlebar  60 , are interconnected in such a way that they simultaneously close in a sole movement. 
         [0043]    The possibility of quickly removing the wheels is also advantageous when replacements or repairs are required, e.g., in case of puncture of a tire. 
         [0044]    A preferred embodiment has been described herein, but of course many changes may be made by a person skilled in the art within the scopes of the claims. In particular, although the bicycle according to the preferred embodiment is provided with spokeless wheels, of course, it could also be provided with traditional wheels with spokes, with mere constructional changes which will be obvious to the person skilled in the art. For instance, fork  58  could be extended in order to support the front wheel at the hinge axis thereof, and lower arm  20  could be suitably shaped in such a way that it supports the rear wheel at the hinge axis thereof. In this case, of course, upper arm  22  can be reduced in length because it does not have to support the rear wheel any more. Moreover, it is evident that other safety locking means could be provided by the skilled person in order to prevent accidental closing of the frame. Of course, mere constructional changes obvious to the skilled person should be included within the scope of the claims. For instance, jaws  68 ,  70  could be made from a single piece, rather than being two different elements. Furthermore, the sector gears could be replaced by engagement angular sectors of a different type, such as friction sectors forming a friction gearing, and the like.