Patent Abstract:
An electrically powered vehicle includes a frame mounted motor connected to pedals and to a rear driven wheel through an intermediate jackshaft. The motor is connected to the jackshaft through a chain or belt. The pedals are connected to the jackshaft through a chain or belt and a jackshaft-pedal freewheel which allows the pedals to drive the jackshaft, but prevents the jackshaft from driving the pedal. The jackshaft is connected to the driven wheel through another chain or belt, and a second freewheel allows the jackshaft to drive the driven wheel but prevents the driven wheel from driving the jackshaft using the same chain or belt. Another chain or belt may additionally connect the driven wheel to the jackshaft through a third freewheel to recharge batteries during braking or while coasting downhill.

Full Description:
[0001]     The present application is a Divisional of U.S. patent application Ser. No. 10/691,951 filed Oct. 23, 2003, which application is incorporated in it&#39;s entirely herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates in general to electric powered bicycles, and more particularly to new, improved technology for electric powered bicycles that provides, among other things, steeper and more efficient hill climbing ability, longer range, and a smother ride than the prior art, plus downhill regenerative braking.  
         [0003]     Prior art electric drives for bicycles can be divided into the following four basic types:  
         [0004]     (1) Friction drive on the tire;  
         [0005]     (2) Drives through the pedal shaft to the rear wheel;  
         [0006]     (3) Direct drives to the rear wheel; and  
         [0007]     (4) Wheel hub motors.  
         [0008]     The cheapest and simplest type of electric drive for a bicycle is a friction drive on the front or rear tire. This method is so inefficient that it is almost impractical. However this type will probably continue to be built and sold, because they can be easily installed on an existing bicycle as a kit. U.S. Pat. No. 6,065,557 to von Keyserling, U.S. Pat. No. 5,316,101 to Gannon, and U.S. Pat. No. 3,961,678 to Hirano contain examples of this type of drive.  
         [0009]     State of the art drives through the pedal shaft to the rear wheel are usually heavy, bulky gearboxes with electric motors attached and a pedal shaft protruding on each side. The advantage of this type of drive is that the rear wheel is driven through the normal pedal chain by the pedals and the motor, or by the pedals alone. Therefore, a normal multi-speed bicycle rear drive can be used to improve hill climbing ability and efficiency. There are a few versions that allow the motor to drive the rear wheel without turning the pedals, but they require additional mechanisms, which increase the cost.  
         [0010]     A disadvantage of this type of drive is that the pedal shaft turns at about one third of the speed of the rear wheel in high gear; therefore, the rotational speed of the motor must be reduced about three times further when driving through the pedal shaft, than when driving the wheel directly. And then, as the power from the motor is transmitted on through the pedal shaft to the rear wheel it has to be sped up again, to about three times the pedal shaft speed. Both the additional reduction and the subsequent up-speed add to the friction losses and cause a significant loss in overall efficiency.  
         [0011]     Electric bicycles must carry a large amount of battery weight to have an effective range, and for safety and maneuverability it is very important to keep that weight low and toward the center of the bicycle. Therefore, another disadvantage of driving through the pedal shaft is that the bulky transmission and motor combination around the pedal shaft causes the battery to be relegated to a higher position, away from the center of the bicycle. U.S. Pat. No. 6,230,586 to Chang, U.S. Pat. No. 6,131,683 to Wada, and U.S. Pat. No. 6,015,021 to Sonobe each disclose a different configuration of a drive through the pedal shaft to the rear wheel.  
         [0012]     Direct drives to the rear wheel take many different forms, but one disadvantage common to all of them is that they require another drive chain and sprocket, or belt and pulley to the rear wheel, in addition to the customary pedal chain and sprocket. Also, in order to pedal the bicycle efficiently when the motor is not in use, another ratcheting device (commonly called a “freewheel”) is required between the extra sprocket or pulley and the rear wheel hub. U.S. Pat. Nos. 6,011,366 to Murakami, 5,937,964 to Mayer, and 5,433,284 to Chou are examples of direct drive to the rear wheel.  
         [0013]     Wheel hub motors look similar to the normal bicycle hub having flanges with holes for spokes on each side and an axle through the center. However they are much larger in diameter, about six to ten inches, and much heavier, about ten to fifteen pounds. They are made for either front or rear wheel application, but when applied to the front wheel of a bicycle, they create a gyroscopic force that at high speed makes the bicycle hard to steer and dangerous in some conditions. When applied to either end of the bicycle, wheel hub motors increase the polar moment of inertia significantly in both the vertical and horizontal planes. It is well known by those skilled in the art of designing vehicles that this is a highly undesirable characteristic from a handling and safety point of view. When applied to the front of a bicycle with front suspension, the large increase in un-sprung weight renders the suspension practically ineffective, and the same is true at the rear. U.S. Pat. Nos. 6,286,616 to Kutter, 6,093,985 to Chen, and 6,015,021 to Tanaka teach different configurations of wheel hub motors.  
         [0014]     At constant voltage, as the required torque increases, the speed and the efficiency of a direct current electric motor of the type used on electric bicycles decreases. Therefore, a bicycle with a single gear ratio electric drive is very inefficient when climbing a hill, because it must slow down to develop the required torque to overcome the hill. In moderately hilly terrain, this inefficiency can cut the range of the bicycle in half. The steeper the hill, the less efficient the motor becomes. On a long hill, this wasted energy usually heats up the motor enough to open the thermal protection switch and turn off the power before the bicycle reaches the top of the hill.  
         [0015]     Common bicycle multi-speed drives, such as multi-speed hubs or rear derailleurs, drive the rear wheel through a freewheel device, so that the pedals do not turn while coasting. Therefore, any of the prior art bicycles that used this type of devices to increase the hill climbing ability of the motor do not have the ability to recharge the battery through the electrical generation capability of the motor while coasting downhill. In fact, there does not seem to be any evidence that there has ever been a bicycle with more than a single gear ratio electric drive that had the ability to drive the motor while coasting downhill. This ability is important to extending the range of the electric bicycle, because most electric motors have the ability to act as generators when connected to the correct circuitry.  
         [0016]     Accordingly, the need exists for an electric powered bicycle that incorporates the following important features:  
         [0017]     (1) A simple, inexpensive multi-speed rear wheel drive that can be driven efficiently by either the pedals or the motor independently or both in unison, without losing the ability to drive the motor as a generator for charging the batteries while pedaling or coasting downhill.  
         [0018]     (2) A shifting device that can be used to shift the multi-speed drive to greater speed reductions as the bicycle begins to climb steeper hills. (When the hub shifts to larger reductions, the torque required from the motor to climb the hill is reduced and the efficiency increases.)  
         [0019]     (3) A motor/drive unit and large battery container that can be fitted to an existing bicycle design in a position that is low and close to the center of the bicycle.  
       BRIEF SUMMARY OF THE INVENTION  
       [0020]     The simplest, most efficient way of accomplishing the intent of this invention is to use one of the newly developed, highly efficient, gear-less, brush-less, direct current, electric, rear hub motors, but not installed in the wheel as the manufacturer intended. Instead, the axle of the hub motor is mounted to brackets that are, in turn, mounted to the frame of the bicycle, just forward of the rear wheel. Because the motor is designed to turn at the speed of a bicycle wheel, a sprocket of about the same size as the sprocket on the multi-speed hub can be fixedly mounted to the rotatable outer case of the motor, beside the conventional freewheel, and concentric to the motor axle. A conventional bicycle chain can then be operatively connected around the two sprockets to drive the rear wheel. The difference in the size of the two sprockets must be adjusted to obtain the desired top speed of the bicycle, depending on the highest gear ratio of the multi-speed hub chosen.  
         [0021]     Another conventional bicycle chain is operatively connected around the conventional large sprocket on the pedal shaft and the sprocket on the conventional freewheel, screwed onto the outer case of the motor in the conventional location. This arrangement provides the rider with the ability to drive the motor, and, in turn, the rear wheel by pedaling the bicycle. Since this type of motor offers almost no resistance to rotation when the power is turned off, this bicycle can be pedaled with almost the same ease as a non-electric bicycle with the same rear hub. Fitted with the appropriate circuitry, at the command of the rider, the motor can be pedaled forward to recharge the batteries. This adds only minimally to the effort of pedaling, and it is particularly convenient if the bicycle is on at least a slight downhill grade.  
         [0022]     The first preferred embodiment of the invention additionally provides downhill regenerative braking. The two drive chains described above are preferably located on the right side of the bicycle, as conventional, which leaves the left side open for a forward drive from the rear wheel to the motor. This drive arrangement can be accomplished by fixedly connecting a sprocket to the left side of the outer case of the motor, like the one on the right side, screwing a freewheel onto the left side of the rear hub, and connecting a chain around the two sprockets. Thus, when the power to the motor is turned off and the bicycle is coasting downhill, the rear wheel drives the motor in the forward direction. Fitted with the correct circuitry and at the command of the rider, the motor, when driven at or above approximately half of its full speed, can recharge the batteries and provide braking assistance.  
         [0023]     As is well known by those skilled in the art, the drive function performed by the chain and sprocket arrangement can alternatively be performed by other mechanisms, including gears, shafts, cables, belts and pulleys, cog belts and pulleys, and gear belts and pulleys.  
         [0024]     As is well known by those skilled in the art, the conventional freewheel allows free rotation of the chain and sprocket in one direction, and provides a fixed connection to transfer driving force from the chain to the rotating member (in this instance, the outer case of the motor), when the chain travels in the other direction. As is also well known by those skilled in the art, the function performed by the conventional freewheel can alternatively be performed by a number of other unidirectional rotating devices, such as a clutch bearing fitted with a sprocket.  
         [0025]     This first preferred embodiment also has, among others, the following advantages:  
         [0026]     (1) Since the motor is brushless, and gearless, and turns at very low speed, about 260 RPM (the speed of the a  26 ″ bicycle wheel traveling at 20 MPH), there is almost no friction loss when driving the motor forward, so most of the pedaling or braking energy is converted to electrical power.  
         [0027]     (2) The multi-speed rear hub can be operated to keep both the motor and pedaling speed up even when the bicycle is moving slowly, which provides the necessary torque and efficiency when hill climbing.  
         [0028]     (3) These electronically commutated motors are usually of the three phase synchronous type, which makes the circuitry for regenerative pedaling and braking simple, efficient, and inexpensive.  
         [0029]     A second preferred embodiment of this invention is similar to the first preferred embodiment except that a jack-shaft is rotatably mounted, in place of the motor, in the motor mounting brackets. Then a smaller, slightly higher speed, brush-less, gear-less motor of the type used in the first preferred embodiment, or of the type that has a fixed case and a rotating shaft, is mounted beside the jack-shaft, preferably in the same brackets. The jack-shaft can then be driven at about the same speed as the large motor it replaced, through a small reduction drive from the smaller, higher speed motor. A freewheel is not needed between the motor and the jack-shaft because the small reduction drive (under four to one ratio) would not cause appreciable frictional loss and the regenerative pedaling and braking would still be quite effective. Pedaling can be accomplished through a freewheel on the jack-shaft and a sprocket, fixed to the jack-shaft, would be operatively connected to the sprocket on the rear hub through a bicycle chain, thereby allowing the bicycle to be driven by the motor, through the jack-shaft, to the multi-speed rear hub without turning the pedals.  
         [0030]     As is well known by those skilled in the art, a jack-shaft is an intermediate shaft which receives power through belts or gearing and transmits it to other driven rotating members.  
         [0031]     The second preferred embodiment with the jack-shaft can also be fitted with the downhill regenerative braking. This would be accomplished by screwing a freewheel onto the left side of the rear hub, fixedly attaching a sprocket to the jack-shaft, and operatively connecting a bicycle chain around the two sprockets.  
         [0032]     A third preferred embodiment of this invention is the same as the first preferred embodiment except that the rear hub motor is of the type that contains a high-speed brush motor, a reduction gear assembly (with a ratio of about ten to one or above), and a freewheeling device inside the hub. The freewheeling device inside the hub allows freewheel coasting and ease of pedaling when the motor is not running  
         [0033]     A fourth preferred embodiment of this invention is the same as the third preferred embodiment with the jack-shaft, except that the motor is of the small, high speed, either brush or brush-less type. Because of the large amount of reduction required between the motor and the jack-shaft, a freewheel is used in the reduction drive, preferably on the jack-shaft, for freewheel coasting and ease of pedaling when the motor is not running.  
         [0034]     It can be seen from the description of the prior art and the above summary of the present invention, how this unique, new concept of a simple, multi-speed drive, which is rotated at a speed that creates the least amount of friction loss for both the pedal power up-speed and the motor power reduction, overcomes the efficiency limitations of the prior art. For the first time, a practical, efficient regenerative charging system for an electric bicycle can be accomplished due to this new technology. The present invention also has the advantage of being able to be fitted into an existing bicycle design, just above the pedal shaft, where it does not prevent the battery module from being mounted low (close to the ground) on the frame. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0035]     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:  
         [0036]      FIG. 1  is an illustration of a bicycle, exemplifying a first preferred embodiment of the present invention viewed from the right side.  
         [0037]      FIG. 2  is a view of the drive train of  FIG. 1  with the bracket that holds the motor cut away so that the drive mechanism behind it is visible.  
         [0038]      FIG. 3  is a view of a drive train of a second preferred embodiment of the present invention, utilizing a derailleur mechanism on the rear hub instead of a multi-speed hub with internal gears, like  FIG. 1  and  FIG. 2 .  
         [0039]      FIG. 4  is a view of the drive train of either  FIG. 1  or  FIG. 2  as viewed from the left side of the bicycle, illustrating the regenerative braking mechanism.  
         [0040]      FIG. 5  is an illustration of the drive train of a third preferred embodiment of the present invention with a higher speed motor driving through a jack-shaft to approximate the pedal speed.  
         [0041]      FIG. 6  is a view of the drive train of  FIG. 5  from the left side of the bicycle, also illustrating the regenerative braking mechanism.  
         [0042]      FIG. 7  is an illustration of the drive train of a fourth preferred embodiment of the present invention with a smaller, higher speed motor driving through a jack-shaft for further speed reduction and to approximate the pedal speed with the motor speed. 
     
    
       [0043]     Corresponding reference characters indicate corresponding components throughout the several views of the drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0044]     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims.  
         [0045]     Referring to  FIG. 1 , an electric powered bicycle  10  of the present invention preferably includes a frame and fork assembly  12 , a front wheel assembly  16 , a rear wheel assembly  14 , a seat assembly  18 , a handle bar assembly  20 , a front and rear brake assembly (not shown), a pedal crank assembly  22 , a multi-speed rear hub assembly  24 , a pedal sprocket  26 , a hub motor assembly  28 , a hub motor axle  39 , a drive chain  30 , a pedal chain  32 , a motor support bracket  34 , and a battery module  36 . The battery module  36  is mounted to the frame  12  in a way that makes it easy to remove in the forward direction and easy to replace in the reverse direction. The battery module  36  fits between sprocket  26  and the left side of pedal crank assembly  22  at a position no lower (closer to the ground) than pedal  22  at its lowest position.  
         [0046]     Motor  28  was designed as a bicycle hub motor and, therefore, the outer case turns while the axle  39  remains fixed. Bracket  34  is mounted to frame  12  and supports the flattened axle  39  of hub motor  28  in slots  38  on both sides of bracket  34 . Motor assembly  28  can be adjusted in slots  38  and tightened into position by axle nuts (not shown) on hub motor axle  39  to adjust the tension on chain  32 .  
         [0047]      FIG. 2  is a view of the drive train in  FIG. 1  with the bracket  34  cut away so that a pedal freewheel  40  and the motor sprocket  42  can be seen. Motor sprocket  42  is fixedly and concentrically mounted to the outer case of motor  28 , and chain  30  is engaged to sprocket  42  and the conventional sprocket on the multi-speed hub  24 , so that when the motor turns, it drives wheel  14 . Freewheel  40  is mounted in its conventional position on the case of motor  28  and has the same function in this application as it does when the motor  28  is used as a bicycle wheel motor. When the motor  28  is operating, it does not turn the sprocket on the freewheel  40  or the pedal sprocket  26 , but when the pedals are also operating and the sprocket on the freewheel  40  is rotated as fast as the motor  28 , the pedals can drive the motor, and consequently, the bicycle.  
         [0048]      FIG. 3  is a view of a drive train of a second preferred embodiment of the present invention, utilizing a derailleur mechanism on the rear hub instead of a multi-speed hub with internal gears, like  FIG. 1  and  FIG. 2 . The mechanism in  FIG. 3  is the same as the mechanism in  FIG. 1  and  FIG. 2  except that chain  31  engages sprocket  42  on motor  28  and one of the sprockets on the freewheel, sprocket cluster  25 , on the rear hub (not shown), depending on the position of the conventional bicycle derailleur  23 . Thereby a multi-speed function similar to the hub in  FIG. 1  and  FIG. 2  is provided.  
         [0049]     Referring to  FIG. 4 ,  FIG. 4  is a view of the drive train in either  FIG. 3  or  FIG. 1  and  FIG. 2 , but from the opposite (left) side of the bicycle, illustrating the drive train mechanism used to provide downhill, regenerative braking capability. Driven sprocket  44  is fixedly mounted to the case of motor  28  in the same manner as sprocket  42 , except on the left side of the motor  28  instead of the right side, and chain  48  is operably engaged with sprocket  44  and the sprocket on freewheel  46 . Freewheel  46  is fixedly and concentrically mounted to the left side of the rear hub of the bicycle in the direction that allows the motor  28  to run and turn the sprocket on the freewheel  46  without engaging the hub and turning the rear wheel  14 . Therefore, when the motor is running or the bicycle is being pedaled, or both, the mechanism on the right side will be driving the rear wheel  14  through the multi-speed device, the most desirable method. However, when the bicycle is coasting (i.e., the motor is not driving the rear wheel) the rear wheel  14  is driving the motor  28 , which, with enough speed and the correct electrical circuits engaged, can recharge the battery. The ratio between the numbers of teeth on the two sprockets,  44  and  46 , must be determined by the ratio of the speed of the motor  28  to the speed of the hub  24  in its highest gear. When the motor is driving the multi-speed device, hub  24  or sprocket cluster  25 , in its highest gear, the sprocket on freewheel  46  should drive sprocket  44 , at preferably the same speed as the motor  28 , or slightly slower; but not any faster, or the drive will malfunction.  
         [0050]      FIG. 5  is an illustration of the drive train of a third preferred embodiment of the present invention with a slightly higher speed motor driving through a belt and pulleys, chain and sprockets, gears, or the like, to a jack-shaft  68  to provide a speed reduction drive mechanism to approximate the pedal speed. In this embodiment of the present invention a rotatable jack-shaft  68  takes the place of motor  28  in  FIGS. 1 through 4 . Bearings  70  are rotatably mounted to each end of the jack-shaft  68 , and the outer races of bearings  70  are fixedly mounted to each side of motor bracket  56 , leaving space for multiple sprockets and a jackshaft freewheel  40   a . In  FIG. 5 , bracket  56  is cut away so that the jackshaft freewheel  40   a  and sprockets  52 ,  58 , and  60  can be seen.  
         [0051]     Continuing with  FIG. 5 , a drive (or motor) sprocket  52  is fixedly and concentrically mounted to the outer case of motor  50 , and a motor-jackshaft chain  62  is operably engaged with the sprocket  52  and a jackshaft-motor sprocket  58 , which is fixedly and concentrically mounted on shaft  68 . A jackshaft-hub chain  64  is operably engaged with a jackshaft-hub sprocket  60  (which is fixedly and concentrically mounted on shaft  68 ) and a hub sprocket on the hub  24 , so that when the motor turns, it drives wheel  14  through chains  62  and  64 . A pedal-jackshaft chain  66  is operably engaged with a jackshaft-pedal sprocket  41  on a jackshaft freewheel  40   a  and the pedal sprocket  26  on the pedal crank  22 . The freewheel  40   a  is mounted on shaft  68  in the orientation so that when the motor  50  is operating, it does not turn the jackshaft-pedal sprocket  41  on the freewheel  40   a  nor the pedal sprocket  26 . However, when the pedal crank  22  is also operating and freewheel  40   a  is rotating as fast as the jackshaft-motor sprocket  58 , which is being driven by the motor  50 , the pedal crank  22  can drive the shaft  68 , and consequently, the motor  50  and the rear wheel of the bicycle.  
         [0052]      FIG. 6  is a view of the drive train of  FIG. 5  from the left side of the bicycle, similar to  FIG. 4 , illustrating the drive train mechanism used to provide downhill, regenerative braking capability for this embodiment. The mechanism illustrated here is the same as in  FIG. 4 , except that sprocket  72  (which has the same function as sprocket  44 ) is concentrically and fixedly mounted to shaft  68  instead of the housing of motor  28 . Since the motor  50  is directly connected to the shaft  68  through chain  62  and sprockets  52  and  58 , this drive train functions the same as the drive train in  FIG. 4  and provides the same downhill, regenerative braking capability under the same conditions.  
         [0053]      FIG. 7  is an illustration of the drive train of a fourth preferred embodiment of the present invention with a smaller, much higher speed motor driving through a belt and pulleys, chain and pulleys, gears, or the like, to a jack-shaft to provide a speed reduction drive mechanism for two purposes: one, for further speed reduction before driving the rear wheel; and two, like the mechanism in  FIG. 5 , to approximate the pedal speed with the motor speed. The mechanism illustrated here is the same as in  FIG. 5 , except that pedaling the bicycle forward does not turn the motor  80 . The large freewheel sprocket  88 , which replaces sprocket  58  in  FIG. 5 , is mounted on jack-shaft  68  in the orientation that allows shaft  68  to turn from pedaling without turning the sprocket on the freewheel  88 , but does not allow the motor  80  to turn sprocket  88  without turning the shaft  68 . This arrangement thereby allows the motor  80  to drive the rear wheel, but not allowing the pedals to turn the motor  80 . There is so much friction in the large speed reduction drive required (about twenty to one) when using a small, high-speed motor in an electric bicycle, that the bicycle would not pedal freely if the motor had to be turned. Therefore, this embodiment does not provide downhill regenerative pedaling or braking, but the cost of a small, high speed motor is much less than the motor in  FIG. 2 .  
         [0054]     The present invention encompasses an apparatus and method for a pedal and electric powered vehicle, including a pedal crank and sprocket, an electric motor, a sprocket and a freewheel mounted to the drive portion of the motor, a chain connecting the motor sprocket to a sprocket on the wheel, and a chain connecting the freewheel to the pedal sprocket, so that either the motor or the pedals, independently or in unison, can drive the vehicle.  
         [0055]     The present invention also encompasses an apparatus and method for a pedal and electric powered vehicle having another freewheel mounted to either the wheel hub or the drive portion of the motor, another sprocket mounted to the other of the wheel hub or the drive portion of the motor, and another chain connecting the sprocket to the freewheel so that the wheel can drive the motor for regenerative braking.  
         [0056]     While the present invention has been illustrated by a description of the preferred embodiments and while these embodiments have been described in considerable detail in order to describe the best mode of practicing the invention, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. For example, if mounted in the correct orientations, freewheel  46  and sprocket  44  in  FIG. 4  could be interchanged and still provide the same downhill, regenerative braking capability. Also, the motor housing and battery box could be formed as part of the structural members of a specially designed bicycle frame, with the present invention in mind. Additional advantages and modifications within the spirit and scope of the invention will readily appear to those skilled in the art. The invention itself should only be defined by the appended claims.  
         [0057]     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, 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.

Technology Classification (CPC): 1