Abstract:
An energy transduction and conservation system has a rotatable primary driving arrangement and a rotatable driven arrangement, the driving and driven arrangements cooperating through an energy storage arrangement. The driving arrangement supplies energy to the energy storage arrangement through a one-way driving system which blocks energy release from the energy storage arrangement back to the driving arrangement. Relative rotation of the driving arrangement is transferred to the energy storage arrangement through a first releasable clutch acting on a one-way rotatable hub whereby energy stored is released only through the driven arrangement. A further one-way clutch is actuated by a differential angular rotational speed to disconnect the first releasable clutch and drive the hub at the same time the energy storage arrangement drives the driven arrangement. The first releasable clutch includes release levers pivotally mounted to release the clutch and allows the inner body to rotate in the normally locking direction.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an energy optimization system for enhancing the efficient use of human energy and relates particularly to a system and apparatus for making use of energy, particularly that derived from human endeavour, that might otherwise be wasted or used inefficiently. 
     In one form, the invention is designed to make use of potential energy of a form of human endeavour where the potential energy may otherwise be unused or be used inefficiently. In another form, the invention is designed to conserve human energy in a physical activity where the energy is used to produce work. In a further form, the invention is designed to convert kinetic energy to potential energy and subsequently re-convert the potential energy back to kinetic energy. 
     In many tasks performed by humans in conjunction with machines or tools or other implements or aids, the effort employed by the human to move the tool or aid, or to drive the machine, uses energy supplied by the human. When that energy is inefficiently used, or when the situation of use is such that not all of the energy is utilised for the task, energy may be wasted. For example, in the simple task of riding a bicycle, due to the nature of the cranked pedals through which force is transferred to a driving sprocket to drive the bicycle, the most efficient point of energy use is when the bicycle pedal crank is at the three o&#39;clock position. When the pedal cranks are at the “dead centre” position (six o&#39;clock and twelve o&#39;clock positions), no amount of force applied thereto vertically is converted to rotational work. Consequently, force applied by the rider to the pedals at the top dead position wastes energy of the rider. Forces applied to the pedals between the one o&#39;clock and two o&#39;clock positions, and between the four o&#39;clock and five o&#39;clock positions use energy less efficiently as compared to the energy use at the three o&#39;clock position. 
     Similarly, in rowing a boat, the maximum conversion of energy to work occurs when the oar is substantailly at right angles to the boat. At other positions, energy may be wasted rather than converted to useful work to move the boat through the water. 
     U.S. Pat. No. 5,035,678 discloses a pedal and chain wheel arrangement in which a plurality of springs absorb energy during the driven portion of the pedal movement between about two o&#39;clock and four o&#39;clock positions of the pedals, and release that stored energy during the pedal movement from four o&#39;clock and eight o&#39;clock positions. However, the energy stored in this way also reacts back through the pedals thereby minimising any driving force on the chain wheel and reducing any benefit of storing the energy in the springs. 
     International Patent Application Number PCT/SI2006/000019 recognises the “dead point” problem associated with propulsion of cycles and proposes a rear hub that incorporates a torsion spring to store energy during the pedal stroke. However, with the structure disclosed, the spring acts between the pedals and the driven hub such that the spring produces a force reaction back through the pedals. 
     U.S. Pat. No. 6,161,452 discloses a pedal crank drive for a bicycle having a power transmission spring consisting of a number of individual spring elements supported between the pedal shaft and chain wheel. A damping spring may also be used between the pedal and the chain wheel. Again, however, the springs act to produce a reaction force back through the pedals. 
     It is, therefore, desirable to develop systems whereby the available energy produces useful work. 
     It is also desirable to provide systems whereby energy that is unable to produce work instantaneously is able to be stored and used subsequently. 
     It is also desirable to provide systems for utilising forces applied by humans to drive mechanisms, or move implements or tools whereby energy may be stored for subsequent utilisation to produce work. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention there is provided a system for conserving and using energy during a human activity involving the use of a machine, tool or implement whereby the application of a force during utilisation of the machine, tool or implement causes energy to be stored in energy storing means, the stored energy generating a driving force isolated from the input and which is subsequent used to perform work during selected periods of the activity. 
     In its broadest form, the invention involves the capture and storage of surplus energy found over and above that produced by the forces needed to achieve a desired and efficient rate of acceleration. The stored energy will improve efficiency as it helps to offset deceleration. 
     In one particular application, the system of the invention is adapted for use with a crank operated vehicle, such as a bicycle. However, it will be appreciated that the principles of the invention have broader application and may be used with a variety of human activities involving machines, tools or implements. 
     Crank and eccentric operated mechanisms find various application in many tools and machines. In the instance where such mechanisms are powered by hand or foot, the ability of the operator to deliver power through the crank or eccentric varies according to the position of the crank or eccentric. One example of a crank operated machine is a bicycle where the rider operates a pedal driven crank which transfers force to at least one of the bicycle wheels. However, the force transfer affected by the rider varies as a product of the rotational position of the crank, with, as stated above, the maximum transfer of power occurring at the three o&#39;clock position of the crank and the minimum transfer of power occurring at the twelve o&#39;clock and six o&#39;clock positions of the crank. Consequently, the energy applied to the crank at rotational positions of the crank other than the three o&#39;clock position is used less efficiently to do work. Clearly, it is preferable to use any excess energy and power from the position of maximum delivery for use at the position of minimum power delivery, and therefore maximise the delivery of power through the whole rotation of a crank or eccentric. Accordingly, an embodiment of the invention has been devised with a view to improving the efficiency thereby making better use of the energy expended. 
     Similarly, it is preferable to use available energy and power from delivery to a shaft during times and periods of excess availability for delivery during alternative times, at the control of the operator. 
     In preferred embodiments of the invention, an energy transduction and conservation system is provided which comprises a rotatable primary driving means and a rotatable driven means wherein said primary driving and said driven means cooperate via an energy storage means, the primary driving means being adapted to supply energy to the energy storage means through a one-way driving system which blocks energy release from the energy storage means back to the primary driving means. 
     In one embodiment of the invention, the relative rotation of said primary driving means, such as a shaft rotated by pedals, is transferred to the energy storage means through a first releasable clutch acting on a one-way rotatable hub which is connected through the energy storage means to the driven means. Thus, because of the one-way operation of the rotatable hub, energy stored is able to be released only through the driven means. As the energy is released, the driven means is caused to rotate in the driving direction at a rate greater than the primary driving means whereby a further clutch is actuated by the differential angular rotational speed to disconnect the first releasable clutch and drive the pedals through the “dead point” at the same time the energy storage means drives the driven means. 
     With this arrangement, at the start of each pedal stroke, the pedal shaft is able to turn at an angular rotational speed greater than that of the driven means, thus causing energy to be stored by the energy storage means. Towards the bottom “dead point”, the rotational force applied by the pedals lessens and the driven means becomes driven by the energy storage means, without the energy rebounding back onto the pedals. Thus, unlike the prior art devices, the pedal movement is not syschronised with the driven means. 
     The first releasable clutch may be of the cam locking type which may include an outer race, an inner body adapted to be mounted on a driven shaft and defining a plurality of circumferentially spaced ramps each having a generally radially extending abutment at one end, and a locking member, such as a roller, in the space between the ramps and outer race. As the inner body rotates in one direction, the abutments engage the rollers which move around the race, and the inner body is able to rotate relative to the outer race. When the inner body is caused to rotate in the other direction, such as when being driven by the pedals, the rollers roll up the ramps and lock the inner body to the race such that they rotate together. The race forms part of the one-way rotatable hub. 
     Preferably, a release lever is pivotally mounted adjacent the end of each ramp and is adapted to engage the respective roller in the locked position. An actuator is associated with each release lever to move the lever into contact with the roller to thereby move the roller out of the locked position to thereby release the clutch and allow the inner body to rotate in the normally locking direction. 
     The series of actuators are preferably axially extending fingers extending from the outer race of a further one-way clutch driven by the driven means. This means that whenever the driven means rotates at an angular rotational speed greater than the pedal speed, by being driven by the energy storage means, the pedals are caused to rotate at that rotational speed. 
     The energy storage means may comprise one or more spiral springs fitted around the axis of rotation of said driving and driven means. Alternatively, the energy storage means may comprise other forms of springs, or extendible bands of rubber, artificial rubber, plastics material, or other extendible material, or compressible material. Magnetic or electrical energy storage means may also be adapted to be used in embodiments of the invention. 
     Pre-tensioning or pre-loading energy into the energy storage means may be provided whereby the primary clutch may cooperate with a lug or abutment screw extending from said driven means to facilitate a selection of a degree of relative rotation between the primary driving means and the driven means so as to provide a selection of pre-tensioning, such as wind-up tension in a spring between the driving and driven means. 
     The one way-rotation of said primary driver means may be provided by a ratchet mechanism, a sprag or cam clutch, one-way bearing or the like. 
     The system of preferred embodiments of the invention may be incorporated into the pedal drive arrangement of a bicycle with the driven means forming the drive sprocket or sprockets for the chain drive of the bicycle. Alternatively, the system of other embodiments of the invention may be incorporated into the rear hub of a bicycle with the primary or secondary driving means forming the chain cluster or sprocket set and the driven means comprising the rear wheel hub. 
     Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 
     Embodiments of the invention will now be described with reference to the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross sectional view of one embodiment of the invention illustrating a drive system as applied to a bicycle pedal drive; 
         FIG. 2  is a sectional view taken along the lines  2 - 2  of  FIG. 1 , 
         FIG. 3  is a sectional view taken along the lines  3 - 3  of  FIG. 1 , 
         FIG. 4  is a sectional view taken along the lines  4 - 4  of  FIG. 1 , 
         FIG. 5  is a sectional view taken along the lines  5 - 5  of  FIG. 1 , 
         FIG. 6  is a sectional view taken along the lines  6 - 6  of  FIG. 1 , and 
         FIG. 7  is a sectional view similar to that of  FIG. 6  but showing a modified arrangement of energy storage means. 
         FIG. 8  is a sectional view similar to that of  FIG. 5  but showing a modified form of the releasable primary clutch in a locked position, and 
         FIG. 9  is a sectional view similar to that of  FIG. 8  but showing the clutch in an unlocked position. 
     
    
    
     LEGEND 
     
         
         
           
               10  Bottom bracket 
               11  Pedal axis 
               12  Pedal cranks 
               14  Chain wheel assembly 
               15  Bearings 
               16  Driving hub 
               17  Pedal shaft 
               18  Releasable primary clutch 
               19  Hub spring mounts 
               20  Bearing mount 
               21  Springs 
               22  Chain wheel spring mounts 
               23  Cam clutch 
               26  Outer race 
               27  Inner body 
               28  Ramps 
               29  Abutment 
               31  Roller 
               32  Release lever 
               33  Actuators 
               34  Nib 
               35  Socket 
               36  Outer race 
               37  Clutch 
               38  Boss 
               39  Bearing support 
               40  Flange 
               41  Clutch inner race 
               42  End plate 
               43  Threaded holes 
               44  Bolt 
               47  Flange 
               47  Lug 
               19 ′ Band supports (hub) 
               21 ′ Resiliend band 
               22 ′ Band supports (chain wheel assembly) 
               30 ′ Spring and rod arrangement 
               31 ′ Knuckles 
               32 ′ Integral lever 
               33 ′ Actuators ( FIGS. 8 and 9 ) 
               33   b  Groove 
               33   c  Cam surface 
           
         
       
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings,  FIG. 1  shows a cross-section through the bottom bracket  10  and along the pedal axis  11  of one embodiment of a device designed for use with a bicycle. In this embodiment, the device is fitted as an intermediate mechanical component between pedal cranks  12  and the chain wheel assembly or sprocket  14  of the bicycle crank set. 
     The pedal shaft  17  connecting the pedal cranks  12  is mounted by bearings  15  to the bicycle bottom bracket  10 . 
     The device includes a rotatable primary driving hub  16  mounted for rotation about the pedal axis  11 . The hub  16  is adapted to receive the driving force or torque applied to the pedal cranks  12  through pedals (not shown). The hub  16  is driven through a releasable primary clutch  18  which engages between the pedal shaft  17  and the hub  16 , as shown particularly in  FIG. 5 . Thus, when the pedal shaft  17  is rotated by the cranks  12 , the rotational movement is directly transferred to the hub  16  through the primary clutch  18 . 
     The hub  16  is shown with two spring mounts  19 . A pair of springs  21  ( FIG. 6 ) coiled about the hub  16  engage at their inner ends with the hub mounts  19  and at their outer ends with further spring mounts  22  on the chain wheel assembly  14 . It will be seen that rotation of the hub  16  will cause the springs  21  to be tensioned and, eventually, the springs will commence to drive the chain wheel assembly  14 . 
     The hub  16  is restricted to rotation in the driven direction only by a cam clutch  23  ( FIG. 4 ) mounted between the hub  16  and the bottom bracket  10 . Therefore, tension in the springs  21  is prevented from acting back from the hub  16  through the pedal shaft  17 , and any stored energy in the springs  21  is able to be released only through driving the chain wheel assembly  14 . 
     Referring to  FIGS. 1 and 5 , the releasable primary clutch  18  is of the cam roller locking type which has an outer race  26 , an inner body  27  mounted on the pedal shaft  17 , the body  27  defining a plurality of circumferentially spaced ramps  28  each having a generally radially extending abutment  29  at one ramp end. A roller  31  is housed within the space between each ramp  28  and the outer race  26 . When the inner body is caused to rotate in the driven direction, as shown by the arrow “A”, such as when being driven by the pedals, the rollers  31  roll up the respective ramps  28  and lock the inner body  27  to the outer race  26  to cause them to rotate together. If the outer race  26  rotates in the direction of the arrow “A” at a rotational speed greater than that of the inner body  27 , the rollers  31  are moved out of the locking position and towards the abutments  29 , disengaging from the locking condition, and outer race  26  is able to rotate relative to the inner body  27 . The outer race  26  forms a part of the one-way rotatable hub  16 . 
     The releasable primary clutch  18  further includes a plurality of release levers  32  each pivotally mounted adjacent the end of each ramp  28  spaced from the respective abutments  29 . The release levers  32  are adapted to pivot from an inactive position to an engaged position whereat they engage the respective roller  31  in the locked position. An actuator  33  is associated with each release lever  32  to move the lever  32  into contact with the roller  31  to thereby move the roller  31  out of the locked position to thereby release the clutch  18  and allow the inner body  27  to rotate relative to the outer race  26  in the normally locking direction of arrow “A”. 
     The release levers  32  are important in the operation of the release because, in order to free the trapped rollers  31 , the pressure applied by the inner body  27  must be eased off. To this end, the release levers  32  have a nib  34  at the inner end, the nib  34  being received within a groove or socket  35  in the ramp  28 . The pivotal action of the movement of the release levers  32  caused by the actuators  33  provides a kick back by the nib  34  to the inner body  27  sufficient to release the trapped rollers  31  so that they can then be moved by the levers  32  to a released position. 
     The series of actuators  33  are formed by axially extending fingers extending from the outer race  36  of a further one-way clutch  37  driven by the chain wheel assembly  14  through an integral flange  40  carrying a boss  38  which provides a bearing support  39  and a driving clutch inner race  41 . 
     In operation, rotation of the pedal cranks  12  drives the driving hub  16  through the releasable primary clutch  18 . Relative movement of the hub  16  and chain wheel assembly  14  causes the springs  21  to be tensioned to the extent that the tension forces commence to rotate the chain wheel assembly  14  against restraining forces associated with driving the bicycle forward. When the driving forces on the pedal cranks  12  becomes less than the driving forces developed by the spring tension, and the chain wheel assembly  14  thus commences to rotate more quickly than the driving hub  16 , the relative movement locks the one-way clutch  37  causing the fingers defining the actuators  33  to release the primary clutch  18  whereby the chain wheel assembly  14  drives the pedal cranks  12  through the finger actuators  33 . This means that whenever the chain wheel assembly  14  tends to rotate at an angular rotational speed greater than the pedal speed, by being driven by the energy stored in the springs  21 , the pedals are caused to rotate at that rotational speed. 
     Referring to  FIGS. 1 ,  2  and  3 , the tension in the springs  21  may be selectively pre-tensioned or pre-loaded. An end plate  42  on the chain wheel assembly  14 , as well as forming a bearing support for one end of the chain wheel assembly  14  on the bottom bracket  10 , has a plurality of threaded holes  43 . A bolt  44  is engagable in a selected one of the holes  43  to extend in the axial direction towards a flange  46  on one end of the driving hub  16 . The flange  46  carries a lug  47  against which the bolt  44  engages to maintain a selectable, predetermined tension in the springs  21 . The pre-stored tension is able to be changed by changing the selected threaded hole  43  in which the bolt  44  is engaged. 
     It will be seen that the capacity of the spiral springs  21  to store energy allows the device to quarantine energy made available during those parts of the cycle of rotation where maximum transfer of power is available, including the three o&#39;clock and nine o&#39;clock positions of the crank; where, in the example of a bicycle, the rider is able to apply maximum force to the pedals at the 3 o&#39;clock and 9 o&#39;clock positions and able to apply virtually no force to the pedals at the 12 o&#39;clock and 6 o&#39;clock positions of the crank. In this manner, the device allows the variations in transfer of power of the rider, as occurs during the cycle of rotation of the crank, to more evenly distribute the available power within the cycle of rotation thereby allowing the energy to be conserved and transduced during a normal operating cycle of the device. 
     The particularly preferred embodiment of the invention as detailed above has the device incorporated into a pedal driven bicycle with a device being mounted to the bottom bracket  10  of a bicycle by way of an auxiliary bearing mount  20 . The auxiliary bearing mount  20  replaces the bottom bracket bearing found on a traditional bicycle and provides for the direct mounting of the bearings  15  as well as other support bearings shown particularly in  FIG. 1 . In use in this configuration and adaptation, the device of the invention permits a rider to maximise the available energy during each single rotation of the pedals where the riders ability to exert maximum torque at the 3 o&#39;clock and 9 o&#39;clock positions of the device can be set up by use of the pre-tensioning bolt  44  such that the application of maximum torque at the 3 o&#39;clock and 9 o&#39;clock positions causes the primary clutch  18  to engage the primary driving hub  16  and wind-up the biasing springs while the torque is directed to the chain wheel assembly  14 . Immediately the angle or rotation of the pedal moves down towards the 6 o&#39;clock or 12 o&#39;clock positions, the inability of the rider to transfer significant torque or power at that position of the cycle is compensated by the release or partial release of the energy stored in the spiral springs  21 , which allows the transfer of energy held therein to the chain wheel assembly  14  thereby allowing the bicycle to continue to be driven. In another use of the device in this particular configuration and embodiment, the rider may elect to alter the pre-tensioning bolt position such that the potential energy built up by the spiral springs  21  occurs not within a single rotation of the pedals, but can be caused to occur over a plurality of rotations, with the spiral springs  21  winding up more gradually. In this use and application of the invention, the available energy of the rider in excess can be utilized for example when riding along a flat piece of road to gradually and interceptively wind up the spiral spring where upon the rider approaching a hill or other situation requiring greater energy, the full potential energy of the wound spring can be held and released during an appropriate time when it is of greatest use to the rider. 
       FIG. 7  illustrates a modification of the above embodiment wherein the spiral springs  21  are replaced by a resilient band  21 ′ formed of synthetic rubber, synthetic plastic, or the like. The band  21 ′ is mounted around a plurality of supports  19 ′ and  22 ′ extending from the hub  16  and chain wheel assembly  14 , respectively, the band  21 ′ being able to store and release energy in a manner similar to the springs  21 . 
     In a modification of the releasable primary clutch  18  shown in  FIGS. 8 and 9 , the rollers  31  are replaced by bearing knuckles  31 ′ which are each formed with an integral lever  32 ′ extending from one side thereof. The knuckles  31 ′ are biased into the locking position by a spring and rod arrangement  30 ′, or the like, so that slippage between the outer race  26  and the body  27  is avoided or minimized. In the event that the race  26  moves with an angular velocity greater than that of the body  27 , the knuckles  31 ′ are released from the locking position, in the known manner of a cam clutch, sprag clutch, one-way bearing or the like. Otherwise, in a driving condition with the pedal cranks  12  driving the inner body  27  through the pedal shaft  17 , the inner body  27  is locked to and drives the outer race  26 , which is part of the driving hub  16 .  FIG. 8  illustrates the releasable primary clutch  18  in the locked position with each integral lever  32 ′ angled radially inwardly toward the body due to the partial relative rotation of the respective knuckle  31 ′ when the primary clutch  18  achieves the locked position. 
     With this modification, the actuators  33 ′ are each formed on their front surfaces with a groove  33   b , which faces the end of the corresponding integral lever  32 ′, and a cam surface  33   c . In use, movement of the actuators  33 ′ relative to the inner body  27 , caused through the action of the one-way clutch  37  as previously described, causes the cam surfaces  33   c  of each actuator  33 ′ to engage and lift the respective integral lever  32 ′ thus causing the associated knuckle  31 ′ to partially rotate in the clockwise direction as viewed in  FIG. 9 . The partial rotation of each locked knuckle  31 ′ moves the body  27  a small amount anticlockwise relative to the outer race  26 , sufficient to release the locked knuckles  31 ′ from their locked condition, as seen in  FIG. 9 . In this position, the actuators  33 ′ will drive the inner body through the integral levers  32 ′, the knuckles  31 ′ and the abutments  29  housing the spring and rod arrangement  30 ′ at an angular velocity greater than that of the driving hub  16 . 
     The flat side of each knuckle  31 ′ ensures that the knuckle  31 ′ returns to its correctly aligned position in cooperation with the end of the spring and rod arrangement  30 ′.