Abstract:
A progressive resistance device is provided having a cylinder having an outer wall which defines an inner chamber. The cylinder is carried on an axle and is rotatable thereabout. An eccentric axle surrounds the axle and is rotatable relative the axle. A magnet carrier partially encircles the eccentric axle and carries a magnet. A bearing is nested between the magnet carrier and the eccentric axle. The magnet carrier is rotatable about the eccentric axle on an axis which is eccentric to the axle&#39;s axis, whereby the distance between the magnet and the outer wall is variable as defined by the rotative position of said housing relative said outer wall, which rotative position is governed by the speed of rotation of the cylinder. The progressive resistance device described herein is adapted for use as a roller on a bicycle trainer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the prior filed provisional application Ser. No. 61/704,789, filed Sep. 24, 2012, incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Bicycle rollers have been in use since the early 1900&#39;s. A bicycle roller is a dynamometer for bicycles that is powered by the bicycle rider. A bicycle roller is traditionally comprised of three rotatable cylinders positioned so that the rear wheel of the bicycle rides on two closely-spaced cylinders, and the front wheel of the bicycle rides on a third cylinder. In the typical application, the cylinder under the front wheel is coupled to one of the cylinders under the rear wheel by an elastic band such that the front cylinder is forced to rotate at approximately the same speed as the rear two cylinders. This allows the rider to control the bicycle, with steering enabled due to the rotation of the front wheel. 
         [0003]    In the prior art, the amount of power, or wattage, that the bicyclist is required to exert to ride at a given speed on a bicycle roller was determined by the amount of rolling resistance resulting from tire distress as the tire rolls over each of the cylinders plus the wattage required to drive any external devices which exert resistance on one or more of the cylinders. Rolling resistance is predominantly a function of the cylinder diameter, tire pressure, and bicyclist weight. Relying on these factors alone provides a linear relationship of resistance versus speed. Simple devices that add a predictable amount of resistance such as the magnetic eddy-current device of U.S. Pat. No. 6,857,992 (incorporated herein by reference) can be added externally to the cylinders, but these are undesirable since they provide a linear speed-to-resistance relationship. 
         [0004]    Prior art bicycle rollers have a linear relationship of speed versus resistance. This solution is unsatisfactory; when beginning to pedal the bike from rest on rollers, low resistance is desired to allow the wheels to accelerate quickly enough to enable sufficient steering dynamics to keep the bicycle stable on the rollers, however, to obtain a meaningful training session, a high amount of resistance is desired when pedaling at a rate suitable to achieve cardiovascular exercise benefit. 
         [0005]    To achieve both objectives it is desired to have a “progressive” resistance relationship with speed. In other words, a non-linear relationship between speed and resistance where the slope of resistance versus speed increases with increasing speed is desired. This relationship is preferred because it mimics the non-linear effect of combined rolling resistance and wind resistance experienced when riding a bicycle in traditional fashion. 
         [0006]    Stationary trainers that use devices external to the rollers, such as fluid resistance, friction, air-moving technologies or variable magnetic resistance devices (see U.S. Pat. No. 7,011,607, incorporated herein by reference) are designed to resemble realistic bicycle riding conditions. Each of these devices is external to the roller. Other than adding this type of device to a bicycle roller, and driving it through a power-transmission device, or through a complicated mechanical coupling to one of the driven cylinders, no attempt has been made to fully integrate progressive resistance technology within the drum of a bicycle roller so that external devices are not necessary. As such, an improved bicycle roller is desired. 
       SUMMARY OF THE INVENTION 
       [0007]    This disclosure describes an improved progressive resistance device suitable for integration with a bicycle roller training device. The progressive resistance device is a conductive cylinder, or drum, having an outer wall defining an internal chamber. One or more magnets is carried on a magnet carrier and housed within the internal chamber and in proximity to the wall. Eddy currents produced in the conductive cylinder as the cylinder spins alter the magnet&#39;s proximity to the wall by forcing the magnet carrier to move in an eccentric orientation as relates to the axis of rotation of the cylinder. A torsional spring opposes the force created by the eddy current and causes the system to achieve a state of equilibrium force balance. 
         [0008]    With the cylinder oriented such that rotation allows the magnet carrier to move against the torsional spring, the result is a progressive relationship between speed and resistance. 
         [0009]    Another benefit of the progressive resistance device described herein is that when a linear relationship between speed and resistance is desired, the cylinder may be reversed—such that the cylinder rotates in the opposite direction described above—allowing the same progressive resistance device to provide either linear or proportional training depending on the direction of rotation of the cylinder. With the progressive resistance device reversed, the result will be a linear relationship of speed and resistance. Therefore, the progressive resistance device described herein is unique in that it allows the user to select progressive resistance or linear resistance, as desired. The ability to make this selection is important because a user training on rollers on any given day may prefer high wattage or low wattage at high speed. In practice, the progressive resistance device is removable from the frame and is reversible, to allow the user to select linear or progressive resistance. 
         [0010]    For most bicycle riders, the use of a trainer having a single progressive resistance device described herein may be adequate. However, because a bicycle roller comprises three cylinders, typically identical, the use of one, two, or three progressive resistance devices described herein may be used in the place of the roller&#39;s cylinders to achieve differing levels of resistance. 
         [0011]    By adjusting the spring rate, spring preload, number of magnets and other variables it is possible to adjust the progressive relationship between resistance and speed to suit the needs of the designer or the user. 
         [0012]    An additional embodiment of this technology to achieve a higher level of resistance on a single cylinder is to include stationary magnets on the outer side of the progressive resistance device placed and oriented in such a way that: a) when the progressive resistance device is at rest, the poles of the moveable magnets inside the cylinder oppose the stationary magnets outside the cylinder, thereby reducing the magnetic flux on the conductive cylinder wall and b) when the progressive resistance device rotates during its normal operation, the moveable magnets inside the cylinder approach stationary magnets on the outside of the cylinder in such a way that the magnets are attracted by appropriate pole alignment, thereby increasing the magnetic flux on the conductive cylinder wall. 
         [0013]    Further, the progressive resistance device described herein is applicable to other stationary trainers, such as those sold for use with bicycles, handcycles and tricycles (see U.S. Pat. Nos. 7,011,607, 7,585,258, 6,964,633, and 6,042,517, each incorporated herein by reference). The progressive resistance device described herein is distinguishable from the magnetic resistance system for rollers (U.S. Pat. No. 6,857,992, incorporated herein by reference) in that the progressive resistance device automatically adjusts resistance level relative to speed, rather than being manually adjustable. 
         [0014]    Applications of this technology are not limited to bicycle rollers and bicycle trainers, but are suitable in any application where a resistance mechanism is employed and it is desired that the resistance mechanism have a non-linear relationship to speed, such as a stationary bicycle, hand cycle ergometers, and any similar device. Because the progressive resistance device described herein is contained within a cylindrical drum and requires only that the outer cylinder be rotated, it can be driven by direct contact with a bicycle tire, or it can employ a chain and sprocket, a drive belt or it can be driven directly by any means to cause rotation of a cylinder on an axle. 
         [0015]    A roller-type stationary bicycle trainer includes a framework typically consisting of two frame members flanking and adjoined to three cylindrical roller drums. Each frame member consists of two parts: a front frame member that allows for various placements of the front cylindrical roller drum relative to the two rear cylindrical roller drums and a rear frame member which is adjoined to the two rear cylindrical roller drums. In one instance, the frame members are pivitolly attached to each other to enable the trainer to fold for storage. It is understood that this description is only indicative of one type of trainer such as the type designed and produced by SportCrafters, Inc. from Granger, Indiana known as the ZRO aluminum or ZRO PVC. Other configurations of attaching cylindrical rollers with a framework intended to appropriately space the rollers and allow for adjustment of the cylinders for use with various bicycles may be employed. 
         [0016]    A power transmission device, which can be a chain, belt or any similar device is typically installed between the front cylinder and the middle cylinder, preferably, an elastic belt. The power transmission device is typically carried in a groove formed in the cap of the cylinder. In other applications the power transmission device is installed between the front cylinder and the rear cylinder. In any case, the power transmission belt is employed to cause the front cylinder to rotate in the same direction, and at approximately the same rate, as either one of the rear cylinders. 
         [0017]    When the progressive resistance device is used, the driven wheel of the bicycle is placed on the two rear cylinders and the front wheel of the bicycle is placed on the front cylinder. When the bicycle is powered by the rider, the rotation of the rear wheel of the bicycle will cause the rear roller drums to rotate, and through the belt drive, this will also cause the front roller drum to rotate in the same direction. Therefore, the front wheel of the bicycle will also rotate in the same direction and approximate speed as the rear wheel of the bicycle. 
         [0018]    In an additional embodiment, a similar roller-type stationary bicycle trainer is provided which is suitable for use with tricycles and handcycles—where the need for the user to balance on the trainer is not required—includes a framework of two rails adjoining two cylindrical roller drums one of the roller drums is a progressive resistance device. It is further understood that this illustration is indicative of the type of trainer designed and produced by SportCrafters Inc from Granger, Indiana sold under the name Mini-roller. In this application, not requiring the skill of the user to balance, the driven wheel of the bicycle is placed between the two roller drums and aligned in such a way that the tire of the bicycle, tricycle, or handcycle remains in contact with the roller drums during use. In a manner as is known, the user pedals the bicycle, tricycle or handcycle so as to rotate the driven wheel which in turn rotates the two cylinders supporting the driven wheel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of a bicycle on a training roller assembly including a progressive resistance device in the place of one of the cylinders; 
           [0020]      FIG. 2  is a cutaway perspective view of the progressive resistance device shown in  FIG. 1 ; 
           [0021]      FIG. 3  is an exploded view of the progressive resistance device of  FIG. 2 ; 
           [0022]      FIG. 4  is a sectional side view of the progressive resistance device of  FIG. 2  and showing three positions of the magnets; 
           [0023]      FIG. 5  is a sectional side view of the progressive resistance device of  FIG. 2  and showing the torsional spring; 
           [0024]      FIG. 6  is a sectional side view of the progressive resistance device of  FIG. 2  and showing the rotational stop 
           [0025]      FIG. 7  is a graph showing power output per rotational speed for various progressive resistance device; 
           [0026]      FIG. 8  is a perspective view of a recumbent tricycle on a training roller assembly; 
           [0027]      FIG. 9  is a perspective view of a hand-cycle on a training roller assembly; 
           [0028]      FIG. 10  is a perspective view of an alternative embodiment of the progressive resistance device having upright members; and 
           [0029]      FIG. 11  is a perspective view of the progressive resistance device having upright members of  FIG. 10 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0030]    In the embodiment depicted in  FIG. 1 , a bicycle  1  having a front wheel  2  and a rear wheel  3 —powered conventionally by means of a crank, chain or other means of applying human power to rear wheel  2 —is positionable on top of a training roller assembly  4 . The roller assembly  4  includes three rotating cylinders, or drums—a front drum  5 , a middle drum  6  and a rear drum  7 —carried by a frame  43 . In one embodiment, the frame  43  is formed having two front frame members  9 , two rear frame members  10 , two hinges  11 , and an elastic drive belt  12 . One of the front frame members  9  is attached by one of the hinges  11  to one of rear frame member  10 , the group forming one side of the frame  43 . Another of the front frame members  9  is attached by another of the hinges  11  to another of the rear frame member  10 , the group forming another side of the frame  43 . The one and the other sides of the frame  43  are joined together by drums  5 ,  6 ,  7  which span therebetween. Drums  5 ,  6 ,  7  are laterally spaced from one another along the frame  43 . The middle drum  6  and the rear drum  7  are spaced apart such that the rear wheel  3  contacts both drums and will not tend to roll over the top of the middle drum while under power. This is typically accomplished by using a ratio of the diameter of the rear wheel  3  divided by the centerline distance between the drums roughly equivalent to 2.5. Therefore, as an example, a 27-inch diameter rear wheel would work well with an 11 inch distance between the cylinders. If the distance between the drums  6 ,  7  were smaller, there may be a tendency for the bicycle to roll over the middle drum when the bicycle is powered by the rider. If the distance were wider, there may be excessive pinching of the tire resulting in very high rolling resistance and tire wear. As the drums  5 ,  6 ,  7  rotate, they contact the surrounding air, and are cooled by forced convection. The drums  5 ,  6 ,  7  are preferably formed from a material which readily dissipates heat, such as aluminum. 
         [0031]    The distance between the front drum  5  and the middle drum  6  is adjusted by anchoring the front drum  5  at any one of a plurality of adjusting holes  14  formed through both of the front frame members  9  such that the front wheel  2  of the bicycle  1  is positioned such that the axle of the front wheel  2  is offset above with the axle of the front drum  5 . An elastic drive belt  12  spans between the middle drum  6  and the front drum  5  such that the front drum  5  turns in the same direction as the middle and rear drums, enabling the bicycle to be operated using the normal dynamics of steering and balance. The elastic drive belt  12  is carried in a groove formed in the cap of the respective drum. 
         [0032]    This disclosure describes a typical bicycle roller assembly  4  as depicted by  FIG. 1  whereby any one, two or three of the drums  5 ,  6 ,  7  house a resistance mechanism  42  as depicted in  FIG. 2  and  FIG. 3 . For the purpose of illustration, the resistance mechanism  42  in  FIG. 2  is represented as the rear drum  7 , but it can be positioned in any of the three locations on roller assembly  4 . 
         [0033]    The resistance mechanism  42  is used in place of one or more of the drums  5 ,  6 ,  7  and is formed having a drum axle  23  which is a straight rod having threaded ends and fasteners  13  suitable for securing the axle  23  to the roller frame  4 . A cylinder  25 , made from electrically conductive material, forms the outer wall of the drum and defines an internal chamber. An eccentric axle  20  encircles the axle  23  and includes a wall having variable thickness. The eccentric axle  20  is rotatable around the axle  23 . A torsional spring  18  includes coils which encircle a portion of the eccentric axle  20 , which spring provides an opposing force to the rotation of the eccentric axle  20 , as described in greater detail below. One or more magnet bearings  19  encircle the eccentric axle  20  and allow a magnet carrier  17  to rotate relative the eccentric axle  20 . The magnet carrier  17  includes a channel  46  for carrying one or more magnets  15 . The magnet carrier  17  encircles the eccentric axle  20  with the magnet bearings  19  sandwiched between the eccentric axle  20  and the magnet carrier  17 . The magnet carrier  17  is preferably formed from a non-magnetic material. The eccentric axle  20  provides the centerline of rotation for the magnet bearings  19 , said centerline being offset from the centerline of the axle  23  by a predetermined amount. The end caps  21  cap the ends of the cylinder  25 , with each end cap  21  having a drum bearing  22  installed into the end caps  21  which bearings allow the cylinder  25  to rotate about the axle  23 . The end caps  21  serve to locate the axle  23  in the center of the cylinder  25 . A rotational stop  24  may be optionally employed to limit the rotation of the magnet carrier  17  about the eccentric axle  20  to enable a limitation to the minimum or maximum resistance as will be described below. The eccentric axle  20  includes one or more axial grooves for accepting an end of the spring  18 , thereby holding the end of spring in fixed rotation with the eccentric axle  20 . The magnet carrier  17  includes an aperture for accepting another end of the spring  18 , thereby the spring  18  is able to exert a force between the eccentric axle  20  and the magnet carrier  17  when they are rotated relative one another. In one embodiment, the magnet carrier  17  only partially encircles magnet bearings  19 , having an axial gap formed along the length of the magnet carrier. A rib  47  is formed proximate the gap formed in the magnet carrier  17 . The rib  47  contacts the magnet bearings  19 , and ensures contact therebetween; in one embodiment a rib  47  is formed on the magnet carrier  17  on each side of the gap. Similarly, a rib  48  is formed proximate the edge of a gap formed in the channel  46  for purposes of contacting and holding firm a cylindrically-shaped magnet  15 . 
         [0034]    The axle  23  mounts the drum (each of drums  5 ,  6 ,  7  having a separate axle  23 ) to the frame  43 . The cylinder  25  is rotatable about the axle  23 . As described in detail below, rotation of the cylinder  25  causes the resistance mechanism  42  to resist rotation of the cylinder. As shown in  FIGS. 4 and 5 , when the cylinder  25  is at rest (not rotating), the torsional spring  18  is at its free state and the position of the magnets  15  is held by said spring and/or the optional rotational stop  24  in Positions A or B, or anywhere in this general area. Position A is the point where a maximum gap exists between the magnets  15  and the cylinder  25 , and Position C is the point where a minimum gap exists between the magnets  15  and the cylinder  25 , the gap at position B is approximately 50% of the differential gap as measured at Positions A and C. 
         [0035]    It is important to note that in Positions A, B, and C the magnets  15  must be sufficiently close to the wall of the cylinder  25  to allow a flux field of the magnets  15  to pass through the wall of the conductive cylinder  25 . The presence of the flux field through the wall of the conductive cylinder  25  will cause a flow of electrons, otherwise known as an eddy current, when the cylinder is in motion relative to the magnets  15 . The strength of the resulting magnetic field from the eddy current must be sufficient to rotate the magnet carrier  17  about the eccentric axle  20  as a result of the force exerted on the magnets by the eddy current. The torsional spring  18  applies a force which resists rotation of the magnet carrier  17 . 
         [0036]    Therefore, when the conductive cylinder  25  is rotated in the direction of the arrows shown in  FIGS. 4-6 , the magnet  15  will cause an eddy current to form in the cylinder  25  and will create a localized magnetic field which opposes the field of the magnets  15 ; a force is exerted on the magnets  15  in a direction tangential to the surface of the conductive cylinder in the proximity of the magnets. Constrained by the eccentric axle  20  and magnet bearings  19  the tangential direction of force translates to a circumferential rotation of the magnet carrier  17  resulting in a decreased radial gap between the magnets  15  and the conductive cylinder  25  as the rotational speed of the cylinder  25  increases. 
         [0037]    As depicted in  FIG. 6 , the relative rotation of the magnet  15  and the magnet carrier  17  can be constrained by a rotational stop  24  wherein the stop  24  has an inwardly-extending tab  44  which seats in the groove  45  of the eccentric axle  20 . An outwardly extending tab  49  is formed on the stop  24  which restricts rotation of the magnet carrier  17  by contacting the edges of the magnet carrier which form the axially-extending gap formed in the magnet carrier  17  opposite the channel  46 , thereby limiting the rotation of the magnet carrier  17  relative the eccentric axle  20 . 
         [0038]    There is a direct relationship between the speed of rotation of the conductive cylinder  25  and the degree of rotation of the magnet carrier  17 . Said relationship is most easily understood by the principle that faster rotation between a conductive surface relative a magnet produces higher electron flow and eddy current in the conductive material, resulting in a stronger magnetic field produced by said eddy current. This magnetic field exerts a force on the magnets  15  which in turn rotates the magnet carrier  17  about the eccentric axle  20 , which rotation is resisted by the torsional spring  18 . Therefore, there exists a higher amount of induced torque on the torsional spring at higher cylinder rotational speeds and the spring will wind up until the torque balances the resistive spring force. For a given rotational speed of the conductive cylinder  25 , a given force balance will exist between the magnet  14  and the torsional spring  18  which will correspond to a given resistive force acting against the rotation of the conductive cylinder at that given speed. 
         [0039]    Further, there is a direct relationship between the degree of rotation of the magnet carrier  17  and the power required to continue rotating the conductive cylinder  25 . Since it was already established that the degree of rotation is directly related to torque, and that power is proportional to torque times angular velocity, then it can be said that more power is required to rotate the cylinder a higher velocity. 
         [0040]    A non-linear relationship between power and cylinder rotational velocity is established by causing the magnets  15  to change their flux density through which the cylinder must pass as the speed of the cylinder increases. In the first embodiment, this is done by the magnets  15  rotating on a centerline that is eccentric to the axis of rotation of the conductive cylinder  25 . In this embodiment, the centerline of the axle  23  and the centerline of rotation of the magnet  15  and the magnet carrier  17  are offset from one another by the eccentric axle  20 . 
         [0041]    The resulting relationship between speed of rotation and power is demonstrated by  FIG. 7 , which shows data points taken from product testing of the configuration represented herein. The X-axis represents bicycle speed as measured in miles per hour (MPH), which is directly proportional to cylinder rotational speed. The Y-axis represents power produced by the rotation of the cylinder  25 , as measured in Watts. The non-linear increase in power with increasing speed is similar to actual conditions when riding a bicycle outdoors, representing the combined effects of rolling resistance and aerodynamic resistance. 
         [0042]    In one embodiment, a rotational stop  24  is employed to limit the rotation of the magnet carrier  17  relative the cylinder  25 , as described above. Limiting rotation in either direction of rotation will limit the range of magnet gap between the cylinder and magnet which will have a corresponding effect on resistance to allow production of a desired power/speed curve. 
         [0043]    The resistance mechanism  42  described herein can be employed on other devices used with human-powered three-wheeled vehicles such as tricycles and handcycles. As shown in  FIGS. 8 and 9 , a smaller roller assembly using two rotating drums is employed to allow the driven wheel to rotate under human power while the vehicle remains stationary. One or both of the drums in this embodiment can house the resistance mechanism of the present disclosure. 
         [0044]      FIG. 8  shows an alternative embodiment where the rear wheel  27  of a recumbent tricycle  26  is mounted on top of a trainer  29  consisting of two cylindrical drums—a front drum  30  and a rear drum  31 —and a frame having two rails  32  to which the drums are affixed. In this embodiment, either the front drum  30 , the rear drum  31 , or both, house the resistance mechanism  42  as heretofore described. 
         [0045]      FIG. 9  shows an additional embodiment where the front wheel  34  of a handcycle  33  is mounted on top of a trainer  35  consisting of two cylindrical drums—a front drum  36  and a rear drum  37 —and a frame having two rails  38  to which the drums are affixed. A pair upwardly-extending arms  39  are affixed to the frame, each extending upwardly from one of rails  38  in such a way that each arm can be adjusted to contact one of the outer rails of the handcycle&#39;s leg rests  40 . The arms  39  are positioned in such a way that they contact the leg rests forward of the axis of steering rotation so that the handcycle remains stable as it is being pedaled on the trainer  35  by the user. In this embodiment, either the front drum  36 , the rear drum  37 , or both, house the resistance mechanism  42  as heretofore described.  FIG. 10  shows an alternative embodiment of the trainer  35  as used with a handcycle  33 . 
         [0046]    A further embodiment includes a cylindrical magnet (not shown) which is mounted in close proximity to the outer surface of the conductive cylinder  25 . In this embodiment, the magnet does not rotate on a concentric centerline to the drum centerline, but instead is initially oriented such that the equator of said magnet(s) is oriented toward said conductive cylinder when the cylinder is at rest. As said cylinder rotates, the cylindrical magnet(s) (not shown) will rotate on their axis against a torsional spring  41  (not shown) such that one of the poles of the magnet will become oriented in the direction of the conductive cylinder as the cylinder  25  increases in rotational speed. Since the magnetic flux field near the equator of a cylindrical magnet is less dense than the magnetic flux field at the magnet&#39;s poles, the effect of power versus cylinder rotations speed is comparable to the embodiment with magnets positioned inside the conductive cylinder. 
         [0047]    It is understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects. No specific limitation with respect to the specific embodiments disclosed herein is intended or should be inferred. Modifications may be made to the disclosed subject matter as set forth in the following claims.