Abstract:
A regenerative braking system for a vehicle, motorized or otherwise, that captures and stores the braking energy of the vehicle through the mechanical compression of a volume of pressurized gas contained in one or more onboard gas springs. This stored energy can be selectively released by the driver to assist with the acceleration of the vehicle from a stopped or moving condition. The compression of the volume of gas is accomplished by the insertion of a plunger into the cylinder of a gas spring by a mechanical spooling cable arrangement powered by the rotative braking of the vehicle. The release of the stored energy is accomplished by the withdrawal of the piston which acts through the spooling cable arrangement to transmit torque to the vehicle&#39;s drive train. The system can be implemented in various motorized or non-motorized vehicles.

Description:
[0001]    The entire disclosure U.S. Provisional Application No. 61/168,852, filed Apr. 13, 2009 the benefit of which is claimed, is considered to be a part of the disclosure of the accompanying application and is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a system of capturing and storing the energy of a moving vehicle during the braking process for the future redirection of that stored energy into the vehicle&#39;s propulsion system. In this “green” age this regenerative braking system fulfills a longfelt need in the field of vehicular energy conservation. This new invention utilizes and combines known and new technologies in a unique and novel configuration to overcome the drawbacks and problems in the prior art. 
       SUMMARY OF THE INVENTION 
       [0003]    The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a vehicular regenerative braking system that is able to safely store energy that is recaptured during the vehicle&#39;s braking process and provide a means for the driver to return this stored energy in the form of additional torque that they selectively input into the vehicle&#39;s propulsion system, wether motorized or otherwise. 
         [0004]    It has many of the advantages mentioned heretofore and many novel features that result in a new vehicular regenerative braking system which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art, either alone or in any combination thereof. 
         [0005]    In accordance with the invention, an object of the present invention is to provide an improved vehicular regenerative braking system capable of capturing and storing energy during braking for selective redirection into the vehicle&#39;s propulsion system. 
         [0006]    It is another object of this invention to provide a gas spring regenerative braking system suitable for motor vehicles as well as bicycles. 
         [0007]    It is a further object of this invention to provide an inexpensive, reliable and safe method for storing and releasing energy captured during vehicular braking into the vehicle&#39;s propulsion system. 
         [0008]    The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a left side view of a partially assembled bicycle showing the general arrangement of all regenerative braking system components; 
           [0010]      FIG. 2  is a right side view of a partially assembled bicycle showing the general arrangement of all regenerative braking system components; 
           [0011]      FIG. 3  is a rear view of a partially assembled bicycle showing the general arrangement of all regenerative braking system components; 
           [0012]      FIG. 4  is a side view of the braking energy capture assembly; 
           [0013]      FIG. 5  is a cross sectional view of the capture energy transfer assembly taken through section A-A of  FIG. 4 ; 
           [0014]      FIG. 6  is a side view of the braking energy transfer assembly; 
           [0015]      FIG. 7  is a cross sectional view of the braking energy transfer assembly taken through section B-B of  FIG. 6 ; 
           [0016]      FIG. 8  is an end view of the braking energy storage assembly; 
           [0017]      FIG. 9  is a cross sectional view of the braking energy storage assembly taken through section C-C of  FIG. 8 ; 
           [0018]      FIG. 10  is a top view representational diagram of the first alternate embodiment regenerative braking system; 
           [0019]      FIG. 11  is a top view representational diagram of the second alternate embodiment regenerative braking system; 
           [0020]      FIG. 12  is an enlarged view of the braking energy capture and transfer systems of  FIG. 11 ; 
           [0021]      FIG. 13  is a top view representational diagram of the third alternate embodiment regenerative braking system; 
           [0022]      FIG. 14  is an enlarged view of the braking energy capture and transfer systems of  FIG. 13 ; 
           [0023]      FIG. 15  is a left side view of the fourth alternate embodiment, 
           [0024]      FIG. 16  is a right side view of the fourth alternate embodiment, 
           [0025]      FIG. 17  is a front view of the fourth alternate embodiment; 
           [0026]      FIG. 18  is an enlarged detail of the one way clutch and sprocket of  FIG. 17 ; 
           [0027]      FIG. 19  is a cross sectional view of the capture assembly of the fourth alternate embodiment; 
           [0028]      FIG. 20  is a side view of the energy transfer assembly of the fourth alternate embodiment; 
           [0029]      FIG. 21  is a cross sectional view of  FIG. 20 ; 
           [0030]      FIG. 22  is a rear perspective view of a partially assembled bicycle showing the general arrangement of all fourth alternate embodiment regenerative braking system components. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
         [0032]    The present disclosure concerns embodiments of a regenerative braking system that utilizes one or more gas springs for capturing and storing braking energy of a vehicle, and then drawing on the stored energy to assist acceleration of the vehicle. Basically, the inertia energy of the moving vehicle is converted into rotational energy during braking (via the braking energy capture assembly), that is converted to linear motion (via the braking energy transfer assembly) that compresses a pre-pressurized gas spring assembly that stores the energy in the form of pressurized gas (via the braking energy storage assembly.) The stored pressure energy is released and transmitted as an applied torque to the vehicle&#39;s propulsion system. The system can be implemented in various motorized and non-motorized vehicles. 
         [0033]    Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. 
         [0034]    One of the most practical examples of the present invention is the principal embodiment of the bicycle regenerative braking system. 
         [0035]    Referring to  FIGS. 1-3 , the components of the bicycle regenerative braking system on a partially assembled bicycle can best be seen. The bicycle regenerative braking system has three major elements: a braking energy capture assembly  2 ; a braking energy transfer assembly  4 ; and a braking energy storage assembly  6 . The braking energy capture assembly  2  is mechanically connected to the braking energy transfer assembly  4  by a looped media such as a roller chain  8  ( FIG. 2 ), and the braking energy transfer assembly  4  is connected to the braking energy storage assembly  6  by a cable  10  thus enabling the capture, transfer, storage and release of the bicycle&#39;s braking energy to and from the bicycle&#39;s rear wheel  12 . It is also well known in the industry that a linear drive line such as a driveshaft/right angled gear coupling could also accomplish the same result. 
         [0036]    Control of the system is provided by an extra caliper brake lever on the left handlebar and twist grip cable pull or cable brake lever on the right handlebar that disengages caliper brake  78  to allow the pressurized, stored gas energy from the braking energy storage assembly to be released and transmitted as an applied torque to the vehicle&#39;s braking energy capture system which is interconnected with the vehicle&#39;s propulsion system. 
         [0037]    Looking at  FIGS. 4 and 5  the components of the braking energy capture assembly  2  can best be seen. Here, conventional bicycle components including a rear wheel hub and sprocket cluster along with a modified caliper brake have been coupled with a planetary transmission assembly and a braking energy drive sprocket  40 . 
         [0038]    Onto the outboard side of a wheel hub  14  is mounted one side of an affixed freewheel clutch  16  that has its other side connected to a sprocket cluster  18 . The wheel hub  14  is connected for rotation about a stationary axle  20  that is housed within a cylindrical bore  22  through the wheel hub&#39;s longitudinal center. The axle  20  is mounted at each end onto a set of rear forks  13 . This type of arrangement is well known in the art. With this setup, the freewheel clutch  16  allows direct coupling between the sprocket cluster  18  and the wheel hub when rotation of the primary chain (not shown), sprocket cluster  18  and the bicycle wheel  12  is in the clockwise direction but uncouples the sprocket cluster  18  and allows the wheel hub  14  to independently rotate (free wheel) about the axle when there is no clockwise rotation of the primary chain and sprocket cluster  18 . 
         [0039]    Onto the inboard side of the wheel hub  14  is mounted a disc brake assembly made of a cable or hydraulically activated caliper  24  that frictionally engages the outer surface of a pair of brake rotor discs  26  separated by a floating friction plate  28 . The left side of the disc brake assembly has a one-way clutch  30  mounted to the outboard side of hub  14  while the right side of the brake rotor discs  26  is connected to a planetary gear set carrier plate  32  of a planetary gear transmission that is mounted on the wheel hub  14 . On the carrier plate  32  is mounted three planet gears  34  that are functionally enmeshed with a sun gear  36  and a ring gear  38 . The sun gear  36  is affixed to the wheel hub  14  and the ring gear  38  is affixed to a ring gear housing  42  which is affixed to a brake energy drive sprocket  40 . The inner race of the one-way clutch  30  is connected to the wheel hub  14  and the outer race is connected to the housing  42  that the ring gear  38  and braking energy drive sprocket  40  are mounted to. This one-way clutch allows the wheel hub  14  and sun gear  36  to rotate forward with respect to the ring gear  38  and braking energy drive sprocket  40 , but not backward. Forward is defined as the same direction as the wheel rotation when the bicycle is traveling forward or traditionally, clockwise. 
         [0040]    In operation, the sun gear  36  of the planetary gear transmission is attached to and rotates with the wheel hub  14  and the brake rotor discs  26  rotate with the planet gear carrier  32 . The brake rotor discs  26  are free to rotate until the rider stops them through the use of a brake lever that is actuated to close the caliper  24  as is well known in the art. Actuating the caliper  24  to stop the brake rotor discs  26  stops the rotation of the planet gear carrier  32  and the planet gears  34  stop revolving around the sun gear  36 . This in turn starts the ring gear  38  rotating in the opposite direction of the sun gear  36 . The brake energy drive sprocket  40  rotates with the ring gear  38  and transmits rotational power through a roller chain  8  to and from the braking energy transfer assembly  4 . 
         [0041]    Because of the planetary gearing, the torque required to stop the planet gear carrier  32  is more than twice the braking torque at the wheel  12 . Because of this, dual brake rotor discs  26  and a floating friction plate  28  are used to increase the stopping torque of the disc brake assembly over that of a standard single disc brake by increasing the frictional drag area on the brake rotor discs  26 . 
         [0042]    Looking at  FIGS. 6 and 7  the components of the braking energy transfer assembly  4  can best be seen. This assembly is rigidly mounted to the bicycle frame by a bracket  46  ( FIG. 1 ) which allows the rotation of a decreasing diameter cable pulley shaft  44  as would be well known in the art. The cable pulley shaft  44  has a roller chain driven first transfer sprocket  48  affixed at one end, a cable pulley drum  50  in the middle, and a one-way transfer clutch assembly  52  affixed at the other end. The first transfer sprocket  48  is fixed to and rotates with the cable pulley shaft  44  and transmits power through a roller chain  8  to and from the brake energy drive sprocket  40 . The cable pulley drum  50  is attached to and rotates with the cable pulley shaft  44 . The cable pulley drum  50  has a concentrically wound cable groove of a decreasing diameter about its axial perimeter that is adapted for engagement with the cable  10 . A strong, flexible cable  10  is wound around the cable pulley drum  50  with one end of it attached thereon by a clamping plate  56  or other suitable constraining arrangement. This end of the cable is thus coilable about the cable pulley drum  50  so as to shorten in length. The other end of the cable  10  is strung around an idler pulley  58  ( FIG. 1 ) and then around a compression pulley  60  ( FIG. 9 ) which is affixed to the end of the gas spring plunger  62 , and then back to the mounting bracket  64  of the braking energy storage assembly  6 . It is well known in the art that the pulley arrangement is a function of the mounted position of the braking energy transfer assembly  4  relative to the braking energy storage assembly  6 . Although in the depicted embodiment two pulleys are used, a different mounting setup utilizing only one pulley has been successfully utilized. 
         [0043]    One-way transfer clutch assembly  52  is affixed to the opposite end of the pulley shaft  44  that the first transfer sprocket  48  is affixed. The inner race of this one-way clutch  52  is attached to the pulley shaft  44  by a frictional locking hub  66 . The outer race of the one-way clutch  52  is attached to a housing  68  that has dual transfer brake discs  70  mounted to it. An extension spring  72  attached to the brake caliper&#39;s actuator arm  74  keeps the transfer caliper brake  78  applied at all times except when the rider releases it by twisting the right handle grip which pulls on the brake release cable  76 . This prevents the cable  10  (once coiled about the cable pulley) from unwinding until the transfer caliper brake  78  is released by the rider. Dual discs  70  and a floating friction plate  80  are used to increase the holding torque of the transfer caliper brake  78  over that of a standard single disc brake as described earlier. 
         [0044]    Looking at  FIGS. 8 and 9  the components of the braking energy storage assembly  6  can best be seen. A gas spring assembly consists of an outer cylinder  82 , an end cap  84 , a charging valve for the pre-pressurization of the enclosed gas, outer cylinder end seals  83 , a guide bearing  86 , a cylinder head  90 , a shaft seal  88 , a plunger  62 , a compression pulley  60 , a piston  92 , and a piston seal  94 . The guide bearing  86  and shaft seal  88  are attached to the cylinder head  90 . The piston  92  is attached to one end of the plunger  62  and is of a larger diameter than the plunger  62 . The piston  92  has a lip seal  94  between it and the cylinder  82  that prevents the flow of gas past the piston  92 . The piston  92  is able to slide axially inside of the cylinder  82  and is captured between the guide bearing  86  and the end cap  84 . The plunger  62  extends through the guide bearing  86  and shaft seal  88  to the outside of the cylinder. The piston  92  can also have at least one recess defined in it&#39;s faces with an orifice  95  in the recess to control the flow rate of the constrained gas from one side of the piston  92  to the other side and thus limit the speed of the travel of the plunger  62 . This acts as a safety feature in the event that the plunger  62  is unrestricted upon a failure of the cable. 
         [0045]    In prototype testing and performance, and under normal operation (6 to 12 inches of plunger travel per second), the orifice  95  has no effect. But should the cable break, the orifice would limit the speed of the plunger to approximately 60 inches per second so that no damage would occur. At the end of the plunger  62  opposite of the piston  92 , a compression pulley  60  is mounted. The inside of the cylinder is charged with approximately 2,000 psi of gas, typically nitrogen. This pressurized gas pushes the plunger  62  out with a force of approximately 1,800 lbs which in turn causes the cable  10  to unwind off of the cable pulley drum  50 , spinning the cable pulley drum  50 , the cable pulley shaft  44 , the first transfer sprocket  48 , the roller chain  8  and the drive sprocket  40  which through the one-way clutch  30  turns hub  14  and the bicycle&#39;s wheel  12 . The bicycle equipped with the above described regenerative braking system operates as follows. When the rider of the bicycle wants to slow or stop, he pulls on the disc brake lever that is connected by a standard brake cable or hydraulic line to the caliper  24  on the braking energy capture assembly  2 . This stops the rotation of the planet gear carrier  32 . Stopping the rotation of the carrier  32  causes the wheel hub  14 , and sun gear  36  to drive the planet gears  34  which in turn drive the ring gear  38  and braking energy drive sprocket  40  in the opposite direction of the bicycle wheel  12 . Through the connection by roller chain  8  and the first transfer sprocket  48  on the cable pulley shaft  44 , the cable pulley drum  50  also rotates in the opposite direct of the wheel  12 . This causes the cable to wind or coil up on the cable pulley drum  50  which in turn tensions and shortens cable  10  forcing the gas spring plunger  62  into the cylinder  82 . The planetary gears, sprockets, cable pulley, and gas spring plunger are all sized in relation to each other to provide a torque to the wheel sufficient to stop the bicycle and rider in a reasonable distance. 
         [0046]    Once the bicycle has stopped the rider can let go of the brake lever connected to the brake caliper  24  on the bicycle&#39;s braking energy capture system. The one-way transfer clutch assembly  52  on the cable pulley shaft  44 , which is being stopped from rotating by the dual discs  70  and transfer caliper brake  78 , prevents the cable  10  from being unwound by the compressed gas force constrained within the cylinder  82  attempting to drive outward the plunger  62 . 
         [0047]    If the bicycle and rider are traveling with more kinetic energy than the braking energy storage assembly  6  has the ability to store, the plunger  62  will bottom out and the torque on the brake rotor discs  26  will increase until they slip in the caliper  24 . To the rider the caliper brake  24  will feel like a normal wheel disc brake. The harder the brake lever is squeezed, the quicker the bicycle will stop. 
         [0048]    When the rider decides to pull away from a stop, he simply twists the right handle grip to release the brake discs  70  on the transfer clutch assembly  52  and allows the force of the gas spring plunger  62  to unwind the cable  10  from the cable pulley drum  50  which in turn causes the pulley shaft  44  to rotate. The first transfer sprocket  48  on the pulley shaft  44  rotates with it and through the roller chain  8  drives the braking energy drive sprocket  40  that is attached to the ring gear housing  42 . The one-way clutch  30  connected between the ring gear housing  42  and wheel hub  14  transmits the torque of the sprocket  40  through to the wheel hub  14  which propels the bicycle and rider forward. 
         [0049]    Because of the planetary gearing in the wheel hub assembly, the torque applied to the wheel during acceleration is higher than the torque applied to the wheel during braking by a ratio equal to the number of teeth on the ring gear divided by the number of teeth on the sun gear. This results in an acceleration rate while starting that is somewhat higher than the rate of acceleration while stopping. 
         [0050]    The wheel hub and transmission can also be configured with the roles of the sun gear  36  and ring gear  38  reversed. That is, with the ring gear  38  connected to the wheel hub  14  and the sun gear  36  connected to the sprocket. This may be desirable because a rider would feel more in control with the lesser acceleration. 
         [0051]    In alternative embodiments, the planetary gearing can be replaced by bevel gears set up in a differential arrangement with the brake being attached to the spider gear carrier. This has the advantage of having a one-to-one ratio which would make braking and starting both have the same acceleration rate. Such mechanical iterations are well known in the art. 
         [0052]    The disclosed system uses two shafts with a chain drive between them. This gives the rider the ability to change sprockets and thus “tune” the system for different weather conditions and rider preferences. Since the same side of the chain is in tension for both braking and accelerating, a simple spring loaded tensioner on the slack side of the chain can be used to take up slack for different sized sprockets. 
         [0053]    One advantage of the bicycle regenerative braking system is that it would prevent the bicycle from rolling backward when stopped on an incline. 
         [0054]    The preferred design is for the cable pulley drum  50  to have a spiral groove for the cable  10  that starts on a large radius and progressively gets smaller as more cable is wrapped onto the pulley. This compensates for the fact that the force of the gas spring plunger  62  increases as the plunger  62  is forced into the cylinder  82 . This results in a more constant braking torque instead of an ever increasing one. 
         [0055]    A rack and pinion could be used instead of the cable and pulley to retract the gas spring plunger. The advantage of a rack and pinion would be that it can be more reliable than the cable and pulley. The disadvantages of the rack and pinion would be that it would be heavier and that it would not compensate for the fact that the force of the gas spring plunger increases as the plunger is forced into the cylinder. 
         [0056]    The functionality of the braking energy capture assembly and the braking energy transfer assembly can be combined into one assembly. This would have the advantage of reducing cost but would increase the rolling resistance of the bicycle because the roller chain and sprockets connecting the wheel to the braking energy capture assembly would be turning at all times, not just when the bicycle was slowing or accelerating. 
         [0057]    By way of a mathematical interpretation, the kinetic energy of a 40 lb bicycle and 190 lb rider traveling at 20 mph approximates 3070 lb-ft. Because of inefficiencies caused by the gears, bearings, sprockets and chain, about 90% of this energy, (2,885 lb-ft) would end up being stored in the gas spring. A 1¾ inch diameter bore gas spring with a 1 inch diameter plunger and an 18 inch stroke that is charged to 2,000 psi with nitrogen has the ability to store 2,900 lb-ft of energy that may be translated to rotational torque for the bicycle&#39;s wheels. 
         [0058]    With the general concept of the present invention disclosed the first alternate embodiment in a motorized vehicle will be described. 
         [0059]    A vehicle drive system comprises the following major components: A gas spring or multiple gas springs to store energy, a ball screw or roller screw assembly to convert the linear motion of the gas springs into rotary motion, a transmission to control the direction of rotation and amount of torque applied to the wheels, and a drive train including a differential assembly to transmit torque to the vehicle&#39;s wheels. 
         [0060]    A ball screw can be used to convert the rotary motion of the wheels to the linear motion of the gas springs. Because a ball screw has constant pitch, it would be desirable to have at least two different gear ratios in the drive train between the wheels and the ball screw to provide more control of the torque applied to the wheels during both stopping and starting. The transmission can contain clutches and gears required to provide both forward and reverse torque to the wheels for stopping and starting the vehicle. The clutches in the transmission can be engaged hydraulically using power supplied by a pump on the vehicle&#39;s engine. A microprocessor can monitor the position of the plungers and the positions of the brake and accelerator pedals to control the operation of the system without the driver needing to operate the vehicle any differently than normal. 
         [0061]    In a typical arrangement as shown in  FIG. 10 , the transmission  105  and differential  103  can be fixed to the vehicle chassis and torque would be transmitted to and from the rear wheels  100  through constant velocity joints  102  and drive shafts. A pinion gear  104  of the differential  103  can transmit torque to and from the transmission  105 . The transmission  105  can contain both forward and reverse gearing to control the direction of torque, either opposing the direction the vehicle is moving (braking), or assisting (accelerating) the vehicle in the direction it is moving. The transmission  105  can also contain gear trains of different ratios to control the amount of torque transmitted to the wheels. Torque from the transmission  105  can be transmitted to and from the ball screw assembly through a one-way clutch  106 . 
         [0062]    The ball screw assembly can be connected to the transmission at the end opposite to the differential. The ball screw assembly would consist of the ball screw  109 , a back stop clutch  108 , a backstop brake  107  connected to the back stop clutch  108 , and a ball screw nut  110 . The ball screw nut  110  converts the rotary motion of the ball screw  109  into linear motion. With the backstop brake  107  engaged, the back stop clutch  108  allows the ball screw to rotate in one direction, that being in the direction to force the gas spring plungers  112  into the gas spring cylinders  113 . This is the energy storage or braking mode. With the backstop brake  107  released, the gas spring plungers  112  are allowed to extend and the ball screw and nut would convert this linear motion into rotary motion that, through the one-way clutch  106 , transmission  105 , and drive train, would apply torque to the wheels and assist in propelling the vehicle. 
         [0063]    The one-way clutch  106  allows a gear ratio in the transmission  105  to be engaged before the back-stop brake  107  is released, ensuring a smooth transition to the accelerating mode. 
         [0064]    Installing this system in an automobile would provide the same fuel savings as an electric hybrid vehicle does but at a lower cost and with less added weight. It also would not have the environmental concerns that the hybrid&#39;s batteries have. The system can be scaled up to buses as well. Since buses make frequent stops, this can result in large fuel savings. 
         [0065]    A 4,500 lb car at 40 mph has a kinetic energy of 240,000 lb-ft. A 9-inch diameter bore gas spring with a 6-inch diameter plunger and a 20-inch stroke that is charged to 2,000 psi with nitrogen has the ability to store 120,000 lb-ft of energy. Two of these gas springs used together has enough capacity to stop a 4,500 lb car from 40 mph and return it to approximately 30 mph. 
         [0066]    A second alternate embodiment is the implementation of the regenerative braking system in a small motorized vehicle. In accordance with a second embodiment, a vehicle regenerative braking system can be comprised of the following major components: A gas spring or multiple gas springs to store energy, one or more high strength rope and pulley assemblies connected to one or more cable drum assemblies to convert the linear motion of the gas springs into rotary motion, a clutch assembly for engaging and disengaging the system, and a drive train including a differential assembly to transmit torque to the vehicle&#39;s wheels. This embodiment would be less expensive than the first alternate embodiment but would be less versatile. Because it lacks a multi-ratio transmission, it would only work in the forward direction and have a limited number of different torques for braking and accelerating the vehicle. The clutch and brakes can be engaged hydraulically using power supplied by a pump on the vehicle&#39;s engine. A microprocessor can monitor the position of the plungers and the positions of the brake and accelerator pedals to control the operation of the system without the driver needing to operate the vehicle any differently than normal. 
         [0067]    Referring to  FIGS. 11 and 12 , a pinion gear  204  of the differential  203  can transmit torque from the wheels  201  and axles  202 , through a clutch  205  and bevel gears  206 , to a cable drum assembly  207 . The cable drum assembly  207  has one end of the cable  220  attached to it. The cable  220  can be strung around a pulley  222  and anchored at the other end by a clamp  221 . The pulley  222  can be attached to a gas spring plunger  223  that is forced into the gas spring cylinder  224  when the cable  220  is wrapped onto the cable drum  213 . 
         [0068]    When the vehicle is moving forward and the clutch  205  is engaged and the planet carrier  209  is stopped by the carrier brake  208 , the sun gear  210  drives the planet gears  211  which in turn drive the ring gear  212  and cable drum in the opposite direction of the sun gear  210 . The one way clutch  214  is mounted between the cable drum  213  and the sun gear shaft and only allows the cable drum  213  to rotate in the opposite direction of the sun gear  210 . When the cable drum  213  turns, it pulls on the cable  220 , which forces the gas spring plunger  223  into the gas spring cylinder  224 . This is the energy storage (braking) mode of the system. The one way clutch  215  has its outer race held from turning by brake discs  216  and spring loaded brake caliper  217 . The one way clutch  215  allows the cable drum  213  to wind up the cable  220 , but does not allow the cable to unwind and propel the vehicle until the caliper  217  is released. 
         [0069]    When the caliper  217  is pressurized, the caliper piston  219  compresses the spring  218  and releases the brake discs  216 . This allows the cable drum  213 , which has the cable  220  pulling on it, to rotate. When the cable drum  213  rotates, it transmits torque through the one way clutch  214  to the sun gear shaft and to the bevel gears  206 . With the clutch  205  engaged, torque is transmitted from the bevel gears  206  to the differential  203  and out to the wheels  201 , which propels the vehicle forward. This is the regenerative (acceleration) mode. 
         [0070]    The clutch  205  can be engaged prior to the caliper  217  being released to prevent the bevel gears from freewheeling and wasting the stored energy. The clutch  205  must be released when the vehicle is required to go in reverse. The clutch  205  should also be released when the system is not being used for either braking or accelerating since releasing it reduces the number of moving parts in the system and thus reduces the overall drag of the system. 
         [0071]    The preferred design is for the cable pulley to have a spiral groove for the cable that starts on a large radius and progressively gets smaller as more cable is wrapped onto the pulley. This compensates for the fact that the force of the gas spring plunger increases as the plunger is forced into the cylinder. This results in a more constant braking torque instead of an ever increasing one. 
         [0072]    It is preferred to have multiple cable drum and gas spring assemblies to give the system variability in braking and acceleration torques. When hard braking is desired, the planet gear carriers  209  of multiple cable drums can be stopped at the same time. When lighter braking is desired, the planet gear carriers  209  can be stopped one at a time. Likewise, when accelerating, releasing multiple cable drum brake calipers  217  at the same time will cause the vehicle to accelerate quickly, while releasing the calipers  217  one at a time will cause the vehicle to accelerate more slowly. 
         [0073]    This second alternate embodiment is made possible because of the new high tech rope fibers that are now available. As an example, a one inch diameter aramid fiber rope can have a breaking strength of 125,000 lbs. In the example below, the maximum pull on the rope would be about 25,000 lbs which is twenty percent of the breaking strength. Twenty percent of breaking strength can be considered a safe working load. This second alternate embodiment would be less expensive than the first alternate embodiment and thus would be desirable for use in smaller, less expensive vehicles. 
         [0074]    A 3,600 lb car at 40 mph has a kinetic energy of 190,000 lb-ft. A 6.5-inch diameter bore gas spring with a 4.5-inch diameter plunger and a 27-inch stroke that is charged to 2,000 psi with nitrogen has the ability to store 92,000 lb-ft of energy. Two of these gas springs used together has enough capacity to stop a 3,600 lb car from 40 mph and return it to approximately 30 mph. 
         [0075]    Whereas the first and second alterative embodiments showed the regenerative braking system implemented on front wheel drive vehicles without any connection to the normal drive train, a third alternate embodiment is the implementation of the regenerative braking system in a rear wheel drive motorized vehicle such as a truck or a bus. Looking at  FIGS. 13 and 14  it can be seen that this system (like the second alternate embodiment) is also comprised of the following major components: A gas spring or multiple gas springs to store energy, one or more high strength rope and pulley assemblies connected to one or more cable drum assemblies to convert the linear motion of the gas springs into rotary motion, a clutch assembly for engaging and disengaging the system, and a drive train including a differential assembly and a transmission to transmit torque to the vehicle&#39;s wheels. In this embodiment, the regenerative braking system is tied into the normal vehicle drive train through the transfer case  226  on the transmission  228 . A second clutch  227  can be used to disengage the engine and transmission during acceleration so that regenerative braking energy is not lost to the engine. The clutch and brakes can be engaged hydraulically using power supplied by a pump on the vehicle&#39;s engine. A microprocessor can monitor the position of the plungers and the positions of the brake and accelerator pedals to control the operation of the system without the driver needing to operate the vehicle any differently than normal. 
         [0076]    There has been no need to this point to describe the actual drive train of the bicycle. These are well known in the art and function independently of the previously described principle embodiment. Generally, this drive train is made up of a crank assembly  15  ( FIG. 22 ) with a toothed sprocket  17  for rotatably housing a proximate end of a roller chain that has its distal end rotatably housed about a sprocket cluster  18  affixed to a wheel hub  14  that is mechanically connected so as to rotate the rear wheel  12  and tire of the vehicle. 
         [0077]    In the earlier described principle embodiment the energy stored and then transferred into the rear wheel and tire was not transmitted through the vehicle&#39;s drive train, but rather was transferred from the braking energy storage assembly through the braking energy transfer assembly to the rear wheel and tire. Here in the fourth alternate embodiment the energy stored is transferred to the rear wheel and tire through a modified vehicle drive train. In this modification the crank assembly  15  has an additional crank sprocket  7  ( FIG. 15 ) and one-way clutch  30  that allows a rotatable connection to a second transfer sprocket  49  ( FIG. 21 ) of the braking energy transfer system via another roller chain  9 . 
         [0078]      FIGS. 15 to 22  show the fourth alternate embodiment. This embodiment is a hybrid of the preferred embodiment wherein it adds additional components to the braking energy transfer assembly and the crank assembly  15  of the drive train. Here the one-way clutch  30  ( FIG. 5 ) out of the braking energy capture assembly is removed and put onto the crank assembly shaft  300 . ( FIG. 15 ) A second transfer sprocket  49  is added parallel and adjacent to the first transfer sprocket  48  of the braking energy transfer assembly. An additional crank sprocket  7  is affixed to the outer side of the one-way clutch  30  which is affixed to the to the crank assembly shaft  300 , and a second roller chain  9  rotatably connects these two sprockets. In this manner instead of the braking energy transfer assembly driving the wheel through the braking energy capture assembly, it would drive the crank assembly shaft  300  via crank sprocket  7  which would then in turn drive the wheel through an attached primary sprocket  17  of the normal drive train which utilizes a third roller chain  11  to rotationally drive sprocket cluster  18  as would be well known in the art. 
         [0079]      FIG. 19  clearly illustrates the energy capture assembly of the fourth alternate embodiment with one way clutch  30  removed and a stabilizing bearing  31  added. In  FIGS. 20 and 21  the second transfer sprocket  49  and the parallel first transfer sprocket  48  configuration can best be seen. 
         [0080]      FIG. 22  shows the general arrangement of the braking energy capture assembly, the braking energy transfer assembly, and the braking energy storage assembly and the drive train of the fourth alternate embodiment. 
         [0081]    This would accomplish two things: first, when accelerating the vehicle, less torque would be applied to the wheel but over a longer distance so as to become more of an assist than a driving force; second, it would allow the rider to store energy in the braking energy storage assembly by pedaling backwards. This would be an advantage if the rider was coming up on a hill and wanted to store some energy ahead of the hill to help climb the hill or if the rider was coming to a stop from a slow speed and wanted to add to the stored energy for a better start away from the stop. 
         [0082]    The above description will enable any person skilled in the art to make and use this invention. It also sets forth the best modes for carrying out this invention. In view of the many possible embodiments, both motorized and not, to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. For example, although the preferred embodiment is configured for use with a bicycle, it could just as easily be used on a tricycle or quadricycle. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.