Patent Publication Number: US-2022239194-A1

Title: Portable electricity generator powered by muscle energy, gravitational energy, or both incorporating fast-charging technology

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Ser. No. 62/965,811, filed Jan. 25, 2020 by the present inventor, which is incorporated by reference in its entirety. 
    
    
     FEDERALLY-SPONSORED RESEARCH 
     Not Applicable 
     SEQUENCE LISTING OR PROGRAM 
     Not Applicable 
     BACKGROUND 
     Technical Field 
     The present invention relates to electrical generators, and more specifically to generators using human muscle energy or gravitational potential energy to charge battery-powered electronic devices via universal serial bus (USB). 
     Prior Art 
     The first electrical generator was created in 1831 by Michael Faraday and was powered by human muscle energy. Generators powered by the action of gravity on water were first created in the 1880s. Innovation to better harness these two sources of electricity, human muscles and gravity, has continued, but each has progressed along its own separate pathway. Recent technological developments have created opportunity not only for accelerated progress along the separate pathways of human- and gravity-powered electricity, but for the pathways to be combined. 
     The following is a tabulation of relevant prior art 
     
       
         
           
               
             
               
                   
               
             
            
               
                 U.S. Patents 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Patent Number 
                 Kind Code 
                 Issue Date 
                 Assignee 
               
               
                   
                   
               
               
                   
                 8,988,038 
                 B2 
                 Mar. 24, 2015 
                 Wilson 
               
               
                   
                 10,263,441 
                 B1 
                 Apr. 16, 2019 
                 Asian 
               
               
                   
                   
               
            
           
           
               
            
               
                 U.S. Patent Publication Applications 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Publication Nr. 
                 Kind Code 
                 Publ. Date 
                 Applicant 
               
               
                   
                   
               
               
                   
                 349,607 
                 A1 
                 Dec. 3, 2015 
                 Nelson 
               
               
                   
                   
               
            
           
         
       
     
     With the emergence of USB fast-charging standards such as USB power delivery (USB-PD), introduced in 2012, and Qualcomm QuickCharge (QC), introduced in 2013, charging devices via USB at up to 100 watts has become possible. 
     Despite these dramatic improvements to charging standards, which have in turn led to the development of higher power wall and car chargers for portable electronic devices now making their way into the market, human- and gravity-powered electricity generators have lagged behind. Of the gravity-powered generators in the prior art, none provide electronic device charging functionality via a USB interface. Of the human-powered generators in the prior art, some do provide electronic device charging functionality via a USB interface (U.S. Pat. Nos. 8,988,038, 10,263,441, and 349,607). However, none of these incorporate the power electronics enabling two-way device communication and power negotiation that USB fast-charging standards require. As a result, the maximum power at which they can charge USB devices, including smartphones, is less than 10 watts-less than half the charge rate at which smartphones are able to charge. All of the prior art in question was developed after the introduction of USB fast-charging standards. Higher power of course means faster charging, and in situations to which a hand-cranked USB charger is most applicable, speed is everything. The last thing a person with a dead phone in a power outage or emergency situation is in a position to do is crank for minutes on end to get their phone to power on, then have it die again because they can&#39;t deliver enough power to keep it running. 
     The shortcoming of these hand-cranked USB chargers is not simply a failure to specify the power electronics allowing them to comply with USB fast-charging standards. To illustrate this point, imagine for a moment that we simply incorporated the updated power electronics associated with USB fast-charging to the hand-cranked USB chargers in the prior art. They would still have difficulty generating more than 10 watts because they do not incorporate a means of securing the generator to a solid object during operation so that it keeps still. In my experience, using one hand to crank and the other to hold the generator or hold it still, as the prior art requires, becomes infeasible with the cranking power associated with USB fast-charging. This operational requirement of the prior art also means that users are unable to crank with one hand while using the other for another task such as operating the electronic device being charged. This scenario becomes particularly likely if the device has just been powered back on after having died, is being used, and requires more power to stay on. Smartphones, laptops, and GPS units are among the devices to which this scenario would apply. 
     I have been obliged to treat the prior art of gravity-powered generators separately from human-powered generators. This is illustrative of another shortcoming of the prior art: a single electricity generator powered by either human muscle energy or gravity, or both at the same time, has not been described in the prior art. Gravity-powered generators tend to use drive mechanisms that convert linear motion to rotary motion that drives the generator, while human-powered generators tend to use rotary input motion directly. Neglecting to accommodate these two types of drive mechanism is among the reasons the prior art has neither diversified its means of harnessing energy from human muscles or gravity, nor been able to combine them. 
     SUMMARY 
     The present invention is a portable power source capable of charging battery-powered electronic devices in compliance with USB fast-charging standards such as USB Power Delivery and Qualcomm Quickcharge. It does this by converting human muscle energy, gravitational potential energy, or a combination of both to electrical power. Human muscle energy or gravitational energy is delivered by a crank arm or a wheel coupled to a first rotational element. 
     Both the crank arm and wheel removably attach to the first rotational element via a collar attached to the first rotational element. This allows a user to choose between the crank arm and wheel as the means of operating the portable power source. It also allows the portable power source to be compactly stored and helps prevent damage during transport. 
     When human muscle energy effects rotation of the crank arm, the first rotational element rotates. When human muscle energy, gravitational energy, or a combination of both effects rotation of the wheel, the first rotational element rotates. Rotation of the crank arm is accomplished by directly rotating the end of the crank arm. Rotation of the wheel is accomplished by pulling a flexible element such as a string wrapped around the periphery of the wheel so that linear motion along the flexible element effects rotary motion of the wheel as the flexible element unwinds from the wheel. The pulling of the flexible element is accomplished by pulling its end in a direction roughly tangential with the wheel, as by the action of walking, biking, or any other means of human transport. The flexible element can be pulled downward by the action of gravity on a weight inside a receptacle connected to the end of the flexible element. Human muscle energy and gravitational energy can effect rotation of the wheel in combination if a person pulls the end of the flexible element while moving downward. This can be done by walking, bicycling, or conducting any other means of human transport down a hill, staircase, or any other physical feature allowing movement that is at least partially downward. One or more humans can also hang with some or all of their weight applied to the end of the flexible element so that the action of gravity on their mass produces the gravitational energy effecting rotation of the wheel. 
     The rate of rotation of the first rotational element is increased via a gear ratio and delivered to a second rotational element. The second rotational element drives a generator that produces a first electrical output, or a combination of voltage and current. The first electrical output is input to a charge control circuit. The charge control circuit is equipped with the ability to negotiate power levels (voltage and current combinations) with attached electronic devices in accordance with USB fast-charging standards. The voltage and current combination output from the charge control circuit, or the DC electrical output, will depend on the voltage and current combination that the charge control circuit has negotiated with the attached electronic device. The DC electrical output is delivered via a USB interface. This interface can include USB-C, USB-A, a combination of both, or any other USB interface. 
    
    
     
       DRAWINGS—FIGURES 
         FIG. 1  is an exploded perspective view of a crank system. 
         FIG. 2  is an exploded perspective view of a rotational element attachment system and part of a crank system. 
         FIG. 3  is an exploded perspective view of a gear ratio and generator, which are prior art. 
         FIG. 4  is an exploded perspective view of a housing system. 
         FIG. 5  is a perspective view of a printed circuit board with a charge control circuit, which is prior art. 
         FIG. 6  is a a perspective view of a printed circuit board with a means of smoothing capacitance. 
         FIG. 7  is a perspective view of a mounting surface securement apparatus. 
         FIG. 8  is an exploded perspective view of a generator system. 
         FIG. 9  is a perspective view of mounted printed circuit boards containing a charge control circuit and a means of smoothing capacitance. 
         FIG. 10  is a perspective view of a generator system. 
         FIG. 11  is a perspective view of the generator system connected to the crank system mounted to a horizontal surface. 
         FIG. 12  is a schematic illustrating the electrical connections among parts of the generator system and an electronic device. 
         FIG. 13  is an exploded perspective view of the mounted generator system and an electronic device. 
         FIG. 14  is a perspective view of the mounted generator system wherein the mounting surface is vertical. 
         FIG. 15  is an exploded perspective view of a wheel system and a rotational element attachment system. 
         FIG. 16  is a perspective view of the mounted generator system attached to the wheel system operable via a hand grip and flexible element wherein the mounting surface is horizontal. 
         FIG. 17  is a perspective view of the mounted generator system attached to the wheel system operable via a flexible element attached to a receptacle containing a mass wherein the mounting surface is vertical. 
     
    
    
     REFERENCE NUMERALS 
       
     
       
         
           
               
               
             
               
                   
               
               
                 Numeral 
                 Name 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 20 
                 Nuts 
               
               
                 21 
                 First Handle Recess 
               
               
                 22 
                 Handle 
               
               
                 23 
                 Handle Through Hole 
               
               
                 24 
                 Spindle 
               
               
                 25 
                 Second Handle Recess 
               
               
                 26 
                 Crank Arm 
               
               
                 26A 
                 Crank Keyed Hole 
               
               
                 26B 
                 Crank Through Holes 
               
               
                 26C 
                 Threaded Hole 
               
               
                 28 
                 Cap 
               
               
                 28A 
                 Recess Holes 
               
               
                 28B 
                 Cap Through Holes 
               
               
                 28C 
                 Cap Wall 
               
               
                 29 
                 Cap Keyed Hole 
               
               
                 30 
                 Collar 
               
               
                 30A 
                 Collar Keyed Hole 
               
               
                 30B 
                 Collar Threaded Holes 
               
               
                 30C 
                 Collar Slot 
               
               
                 30D 
                 Collar Through Hole 
               
               
                 30E 
                 Collar Recess Hole 
               
               
                 30F 
                 Collar Threaded Hole 
               
               
                 31 
                 Shaft 
               
               
                 32 
                 First Rotational Element 
               
               
                 34 
                 Key 
               
               
                 36 
                 Base 
               
               
                 38 
                 Fastener A 
               
               
                 40 
                 Fasteners B 
               
               
                 42 
                 Through Holes 
               
               
                 44 
                 First Electrical Output 
               
               
                 47 
                 Gear Ratio 
               
               
                 48 
                 Gearbox Housing 
               
               
                 49 
                 Flange Through Holes 
               
               
                 50 
                 Generator 
               
               
                 51 
                 Second Rotational Element 
               
               
                 52 
                 Front Closure 
               
               
                 53 
                 Gearbox Flange 
               
               
                 54 
                 Hole Features 
               
               
                 56 
                 Front Through Holes 
               
               
                 58 
                 Base Hole 
               
               
                 60 
                 Tube 
               
               
                 62 
                 Perimeter Threaded Holes 
               
               
                 64 
                 Wide Slot 
               
               
                 66 
                 Recess Pocket 
               
               
                 67 
                 USB Interface 
               
               
                 68 
                 USB-C Slot 
               
               
                 70 
                 USB-A Slot 
               
               
                 72 
                 Rear Closure 
               
               
                 74 
                 Rear Closure Mounting Holes 
               
               
                 76 
                 Rear Through Holes 
               
               
                 78 
                 Charge Control Circuit 
               
               
                 79 
                 Charge Control PCB 
               
               
                 80 
                 First Electrolytic Capacitors 
               
               
                 81 
                 First Ceramic Capacitors 
               
               
                 82 
                 Charge Control Through Holes 
               
               
                 84 
                 USB-C Port 
               
               
                 86 
                 USB-A Port 
               
               
                 88 
                 Electrical Port 
               
               
                 89 
                 DC Electrical Output 
               
               
                 94 
                 Means of Smoothing Capacitance 
               
               
                 96 
                 Second Electrolytic Capacitors 
               
               
                 98 
                 Second Ceramic Capacitors 
               
               
                 100 
                 Mounting Holes 
               
               
                 102 
                 Electrical Interface 
               
               
                 108 
                 Horizontal Mounting Surface 
               
               
                 108A 
                 Face 
               
               
                 110 
                 Rubber Pad 
               
               
                 111 
                 First Flange 
               
               
                 112 
                 Bracket Body 
               
               
                 113 
                 Second Flange 
               
               
                 114 
                 First C-CLamp 
               
               
                 115 
                 Second C-Clamp 
               
               
                 116 
                 Bolts 
               
               
                 118 
                 Front Perimeter Screws 
               
               
                 120 
                 Gearbox Nuts 
               
               
                 122 
                 Charge Control Mounting Screws 
               
               
                 124 
                 Hollow Cylindrical Spacers 
               
               
                 126 
                 Capacitance Mounting Screws 
               
               
                 128 
                 Rear Perimeter Screws 
               
               
                 130 
                 Vertical Mounting Surface 
               
               
                 132 
                 Wheel 
               
               
                 132A 
                 Wheel Keyed Hole 
               
               
                 132B 
                 Wheel Through Holes 
               
               
                 133 
                 Peripheral Securement Feature 
               
               
                 134 
                 First Illustrative Arrow 
               
               
                 136 
                 Second Illustrative Arrow 
               
               
                 138 
                 Third Illustrative Arrow 
               
               
                 140 
                 Fourth Illustrative Arrow 
               
               
                 142 
                 Electronic Device 
               
               
                 144 
                 USB Cable 
               
               
                 146 
                 Second USB-C Plug 
               
               
                 148 
                 First USB-C Plug 
               
               
                 149 
                 Flexible Member Free End 
               
               
                 150 
                 Flexible Member 
               
               
                 151 
                 Hand Grip 
               
               
                 152 
                 Fifth Illustrative Arrow 
               
               
                 154 
                 Sixth Illustrative Arrow 
               
               
                 155 
                 Mass 
               
               
                 156 
                 Receptacle 
               
               
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION 
     Structure and Function 
       FIG. 1  shows a crank system in perspective exploded view. A handle  22  has a handle through hole  23  that allows it to fit onto a spindle  24 . The difference in diameter between handle through hole  23  and spindle  24  is consistent with a clearance fit which allows relative rotational movement between handle  22  and spindle  24 . Handle  22  has a first handle recess  21  that allows nuts  20  to recess into the end of handle  22 . Spindle  24  has threads that allow for nuts  20  to be screwed onto it, preventing handle  22  from sliding off spindle  24 . Tightening the two nuts  20  against each other onto the threads on spindle  24  prevents their self-loosening and their being tightened against handle  22  in a way that would prevent relative rotational movement between handle  22  and spindle  24 . Spindle  24  has threads that allow it to be screwed into a corresponding threaded hole  26 C on a crank arm  26 . The side of spindle  24  closest to crank handle  26  recesses into second handle recess  25 . 
       FIG. 2  shows part of the crank system and a rotational element attachment system in perspective exploded view. A first rotational element  32  is comprised of a shaft  31  and a key  34 . A collar  30  has a collar keyed hole  30 A. The dimensions of the cross section of collar keyed hole  30 A when viewed on the radial plane with shaft  31  is such that it is the same shape but slightly larger than shaft  31  and key  34 . This allows collar  30  to slide onto shaft  31  and key  34 . Collar  30  is positioned onto shaft  31  and key  34  such that there is sufficient clearance between a base  36  and collar  30  to allow for unobstructed rotational movement of collar  30  relative to base  36 . Collar  30  includes a collar slot  30 C that creates an opening between collar keyed hole  30 A and the outer perimeter of collar  30 . Collar slot  30 C has a rectangular cross section when viewed on the radial plane with shaft  31  and extends along the entire axial length of collar  30 . A collar through hole  30 D oriented along the same axis as a fastener A  38  has a diameter allowing a clearance fit between it and fastener A  38 . It extends only to collar slot  30 C. A collar threaded hole  30 F oriented along the same axis as fastener A  38  then extends from collar slot  30 C to the perimeter of collar  30  opposite the head of fastener A  38 . A collar recess hole  30 E with a diameter slightly larger than the head of a fastener A  38  is oriented along the same axis as collar through hole  30 D and extends to a depth allowing the head of fastener A  38  to recess partially into the side of collar  30 . When fastener A  38  is inserted into collar through hole  30 D, it spans the distance of collar slot  30 C and engages the the threads in collar threaded hole  30 F on the other side. As the fastener A  38  is tightened, its head touches the bottom of collar recess hole  30 E and results in a clamping force securing collar  30  onto shaft  31  and key  34 . Some collar threaded holes  30 B extend along the majority of the axial length of collar  30 . Crank arm  26  has a crank keyed hole  26 A that allows it to slide onto shaft  31  and key  34  until crank arm  26  is touching collar  30 . A cap keyed hole  29  in a cap  28  is similar in cross sectional geometry to collar keyed hole  30 A, but it extends only partially along the axial length of cap  28 , leaving a cap wall  28 C that prevents cap  28  from sliding onto shaft  31  beyond the axial depth of cap keyed hole  29 . A pair of cap through holes, one of which is labeled  28 B, have the same diameter and axial orientation as a pair of crank through holes  26 B, allow fasteners B  40  to pass through cap  28  and crank arm  26  to engage the threads in collar threaded holes  30 B on collar  30 . Recess holes oriented along the axes of fasteners B  40  extend to a partial depth along this axis into cap  28 . One of these recess holes is labeled  28 A. As fasteners B  40  are tightened, the bottoms of their heads make contact with recess holes  28 A. This results in a clamping force holding cap  28 , crank arm  26 , and collar  30  together. 
       FIG. 3  shows a gear ratio and a generator. Gear ratios and generators are prior art. A gear ratio  47  is mechanically coupled to a generator  50  via a second rotational element  51 . Gear ratio  47  is comprised of a gearbox housing  48  containing gears that increase the number of rotations per unit time of a second rotational element  51  relative to first rotational element  32 . Four through holes, one of which is labeled  42 , extend for the entire axial length of gearbox housing  48 . A gearbox flange  53  is attached to generator  50  and has four flange through holes, one of which is labeled  49 , of the same geometry and axial orientation as through holes  42 . Gear ratio  47  has a 30:1 gear reduction ratio such that the rotational speed of second rotational element  51  is greater than the rotational speed of first rotational element  32  by a factor of 30. Generator  50  is a 24 volt DC motor designed for operation at 1800 RPM with a rated continuous mechanical output power of 40 watts. Generator  50  converts mechanical input power resulting from the rotation of second rotational element  51  to electrical power at first electrical output  44 . 
       FIG. 4  shows a housing system. A front closure  52  has four hole features at each of its corners, one of which is indicated as  54 . Hole features  54  consist of a through hole extending across the entire thickness of front closure  52  and a larger recess hole extending for only part of the thickness of front closure  52 . Abase hole  58  extends across the full thickness of front closure  52 . Eight front through holes through front closure  52 , one of which is labeled  56 , extend across the full thickness of front closure  52 . A tube  60  incorporates a wide slot  64 . Eight perimeter threaded holes, one of which is labeled  62 , are axially aligned with front through holes  56  and extend to a depth into the tube representing at least two multiples of the thickness of front closure  52 . A USB-C slot  68  allows a male USB-C plug connector to pass without obstruction through to the interior of tube  60 . A USB-A slot  70  is cut such that it allows a male USB-A plug connector to pass without obstruction through to the interior of tube  60 . A rectangular recess pocket  66  creates a surface against which the non-charge plug portion of male USB-C and USB-A plugs inserted into USB-C slot  68  and USB-A slot  70  can make contact, ensuring that the plugs are not inserted too far. The depth of recess pocket  66  allows a sufficient portion of USB-C and USB-A plug connectors to protrude into the interior of tube  60  via USB-C slot  68  and USB-A slot  70  to completely insert into female USB-C and USB-A plugs installed adjacent to the interior wall of tube  60 . A rear closure  72  has six threaded rear closure mounting holes extending along a portion of the thickness of rear closure  72 , one of which is labeled  74 . Eight rear through holes, one of which is labeled  76 , extend through the thickness of rear closure  72 . The pattern of rear through holes  76  is the same as that of front through holes  56 . Threaded holes of the same pattern extend into tube  60  from its side closest to the rear closure  72  to a depth of at least two multiples of the thickness of rear closure  72 . 
       FIG. 5  is a simplified depiction of a charge control printed circuit board (PCB), which is prior art, in perspective view. The charge control PCB  79  depicted in  FIG. 5  is manufactured by Coolgear Inc. and has model number WTF-CG69. It supports a charge output power of 60 W. Charge control PCB  79  has several integrated chips installed on it, including a buck-boost controller chip and a chip that manages the negotiation of power levels between an upstream power source, typically a 12V car outlet or DC power supply, and a downstream power sink, typically a fast-charging-compatible electronic device such as a mobile phone, tablet, drone, camera, or laptop. Together these integrated chips and associated circuitry constitute a charge control circuit  78 . These devices connect to the charge control PCB via a USB cable connected to a USB-C port  84  or USB-A port  86 . USB-C port  84  offers USB Power Delivery, in addition to other standards, and would typically connect to devices operating according to the USB Power Delivery standard, while USB-A port  86  offers various fast-charging standards and would typically connect to devices compatible with Qualcomm Quick Charge, such as Android-based mobile phones, or Apple devices charging at up to 5 volts, 2.4 amps. An electrical port  88  is designed to electrically couple to first electrical output  44 . Several first electrolytic capacitors, one of which is labeled  80 , as well as some first ceramic capacitors  81 , are connected to both the electrical port  88  and a DC electrical output  89  of the charge control PCB  79 . DC electrical output  89  is mechanically and electrically connected to USB-C port  84  and USB-A port  86 . Four charge control through holes, one of which is labeled  82 , allow charge control PCB  79  to be securely mounted. 
       FIG. 6  shows a simplified depiction of a means of smoothing capacitance  94  in perspective view. It consists of three 1000 uF second electrolytic capacitors connected in parallel, one of which is labeled  96 , as well as two ceramic 25 uF second ceramic capacitors, one of which is labeled  98 , connected in parallel to one another and to second electrolytic capacitors  96 . Two mounting holes, one of which is labeled  100 , allow the means of smoothing capacitance  94  to be securely mounted. An electrical interface  102  of the means of smoothing capacitance  94  allows parallel electrical connection to first electrical output  44 . 
       FIG. 7  shows a mounting surface securement apparatus. A horizontal mounting surface  108 , such as a table or counter, has a non-slip rubber pad  110  placed on it. On top of rubber pad  110  is a bracket body  112  with a first flange  111  and a second flange  113 . A first c-clamp  114  is placed such that it contacts a first flange  111 . A second c-clamp  115  is placed such that it contacts a second flange  113 . As first c-clamp  114  and second c-clamp  115  are tightened, they clamp bracket body  112  to rubber pad  110  and horizontal mounting surface  108 . 
       FIG. 8  shows a generator system, including the interaction of generator  50 , gear ratio  47 , the housing system of  FIG. 4 , the charge control PCB of  FIG. 5 , and the means of smoothing capacitance  94  of  FIG. 6 . Bolts  116  extend through hole features  54  on front closure  52 , through holes  42  on gearbox housing  48 , through holes  49  on flange  53 , and into gearbox nuts  120 . Gearbox nuts  120  adjoin gearbox flange  53  while the bottom surface of the head of bolts  116  adjoin the bottom surface of the recess portion of hole features  54  on front closure  52 . In this way bolts  116  tightened into gearbox nuts  120  secure front closure  52  to gearbox housing  48 , which in turn secures generator  50  to gearbox housing  48 . Front perimeter screws  118  extend through front through holes  56  and into perimeter threaded holes  62 . In this way front closure  52  is secured to tube  60  via the tightening of front perimeter screws  118  into perimeter threaded holes  62 . A set of charge control mounting screws  122  extends through charge control through holes  82 , a set of hollow cylindrical spacers  124 , and into rear closure mounting holes  74 . In this way the tightening of charge control mounting screws  122  into rear through holes  76  secures charge control PCB  79  to rear closure  72 . Hollow cylindrical spacers  124  ensure that a gap is maintained between charge control PCB  79  and rear closure  72 . A pair of capacitance mounting screws  126  extends through mounting holes  100  on means of smoothing capacitance  94  and into rear closure mounting holes  74 . In this way the tightening of capacitance mounting screws  126  into rear closure mounting holes  74  secures means of smoothing capacitance  94  to rear closure  72 . A set of rear perimeter screws  128  extend through rear through holes  76  and into threaded perimeter holes in tube  60  of a similar pattern and alignment to perimeter threaded holes  62 . In this way the tightening of rear perimeter screws  128  into threaded perimeter holes on tube  60  secures rear closure  72  to tube  60 . 
       FIG. 9  shows charge control PCB  79  and means of smoothing capacitance  94  mounted to rear closure  72  via charge control mounting screws  122 , one of which is labeled, and capacitance mounting screws  126 , one of which is labeled. 
       FIG. 10  shows the generator system of  FIG. 8  fully assembled including fasteners. Base  36  protrudes through base hole  58 . Rear closure  72  has mounted to it charge control PCB  79  and means of smoothing capacitance  94  as pictured in  FIG. 9 . When rear closure  72  is secured onto tube  60  with rear perimeter screws  128 , one of which is labeled, USB-A port  86  ( FIG. 9 ) aligns with USB-A slot  70  such that a male USB-A charge connector is able to fully insert into USB-A port  86  ( FIG. 9 ). When rear closure  72  is secured onto tube  60  with rear perimeter screws  128 , USB-C port  84  ( FIG. 9 ) aligns with USB-C slot  68  such that a male USB-C charge connector is able to fully insert into USB-C port  84  ( FIG. 9 ). Together USB-A port  86  and USB-C port  84  constitute a USB interface  67 . 
       FIG. 11  shows in perspective view a mounted generator system wherein the mounting surface is horizontal and the crank system of  FIG. 1  is attached. Bracket body  112  fits into wide slot  64  on tube  60  pictured in  FIG. 4 . When first c-clamp  114  and second c-clamp  115  are tightened, tube  60  is secured to horizontal mounting surface  108 . The placement of tube  60  relative to horizontal mounting surface  108  is such that the distance between the plane of crank arm  26  closest to a face  108 A of horizontal mounting surface  108  and orthogonal to it is greater than the maximum orthogonal protrusion of first c-clamp  114  and second c-clamp  115  relative to face  108 A. This allows the crank system to rotate freely as it rotates about the axis of shaft  31 . Tightened fasteners B  40  secure cap  28  to crank arm  26  and collar  30 , which in turn is secured to shaft  31  and key  34  ( FIG. 3 ) by tightened fastener A  38 . 
       FIG. 12  illustrates the electrical connections between generator  50 , means of smoothing capacitance  94 , charge control PCB  79 , and an electronic device  142 . The first electrical output  44  is connected in series to electrical port  88 . First electrical output  44  is connected in parallel to electrical interface  102 . USB interface  67  is capable of connecting in series to electronic device  142  via a USB cable. 
       FIG. 13  illustrates the mounted generator system connected to the crank system wherein the mounting surface is horizontal connecting to an electronic device. A USB cable  144  connects on one end to electronic device  142  by pushing a first USB-C plug  148  into electronic device  142  in the direction of a fourth illustrative arrow  140 . USB cable  144  connects to the generator system by pushing a second USB-C plug  146  through USB-C slot  68  in the direction of a third illustrative arrow  138 , on the other side of which is USB-C port  84  as indicated in  FIG. 5  and  FIG. 9 . 
       FIG. 14  illustrates the mounted generator system connected to the crank system of  FIG. 1  wherein the mounting surface is a vertical mounting surface  130  such as a door. 
       FIG. 15  illustrates a wheel system. Wheel  132  uses the same rotational element securement system depicted in  FIG. 2 , including a wheel keyed hole  132 A and wheel through holes  132 B identical to crank keyed hole  26 A and crank through holes  26 B on crank arm  26  shown in  FIG. 2 . This makes wheel  132  interchangeable with crank arm  26  by loosening and removing fasteners B  40 , removing crank arm  26 , installing wheel  132  in its place, and reinserting and tightening fasteners B  40 , allowing the user to select and install which drive system best suits their preferences or conditions. Wheel  132  includes a peripheral securement feature  133 . 
       FIG. 16  illustrates the mounted generator system connected to the wheel system of  FIG. 15  wherein the mounting surface is horizontal surface  108 . A flexible member  150  encircles wheel  132  within peripheral securement feature  133  multiple times. Hand grip  151  attaches to a flexible member free end  149  of flexible member  150 . 
       FIG. 17  illustrates the generator system connected to the wheel system of  FIG. 15  and mounted to a vertical surface  130 . A receptacle  156  into which is placed a mass  155  attaches to flexible member free end  149  of flexible member  150 . 
     Operation of Embodiments 
     A first embodiment illustrated in  FIG. 11  and  FIG. 13 , as well as a second embodiment illustrated in  FIG. 14 , operates via muscle energy applied to handle  22  in the direction of a first illustrative arrow  134 . This results in rotational energy comprised of rotational velocity and torque at rotational element  32  in the direction indicated by a second illustrative arrow  136 . The torque and rotational velocity of first rotational element  32  are in turn imparted to second rotational element  51  but are modified according to gear ratio  47 . The rotational energy of second rotational element  51  ( FIG. 3 ) generates a voltage and current via generator  50  that charges the connected electronic device  142  ( FIG. 12 ). If the user maintains a rotational speed greater than 60 RPM, the device will charge continuously. 
     A third embodiment illustrated in  FIG. 16  operates via muscle energy applied to hand grip  151  in the direction of sixth illustrative arrow  154 . When hand grip  151  is pulled in the direction of a sixth illustrative arrow  154  tangential to the perimeter of wheel  132 , that linear movement and energy is converted to rotational movement in the direction of a fifth illustrative arrow  152  and energy, which results in first rotational element  32  ( FIG. 3 ) rotating and providing the mechanical torque and velocity to charge an electronic device at USB fast-charging speeds. Once the flexible element entirely unwinds from wheel  132  and rotation of wheel  132  ceases, the flexible element can be rewound circumferentially about wheel  132  within peripheral securement feature  133  multiple times and the process repeated. This results in rotation of wheel  132  in the direction of fifth illustrative arrow  152 . 
     A fourth embodiment illustrated in  FIG. 17  operates via the conversion of gravitational potential energy associated with mass  155  inside receptacle  156  to kinetic energy. When allowed to drop, receptacle  156  and mass  155  pull downward by the action of gravity in a direction tangential to wheel  132  and produce rotational energy. This results in rotation of wheel  132  in the direction of fifth illustrative arrow  152  ( FIG. 16 ) and provision of the mechanical torque and velocity to charge an electronic device at USB fast-charging speeds. 
     Additional Embodiments 
     Additional embodiments result from combining the third and fourth embodiments. Any linear movement tangential to wheel  132  converts linear motion to rotational input energy that the generator system can convert to electrical power for the purpose of fast-charging electronic devices. Flexible member free end  149  ( FIG. 16 ) can be attached to anything capable of performing work in a linear direction. For example, a user could grasp hand grip  151  and walk or run in a direction tangential to wheel  132 , connect the end of the flexible element to a belt or harness and walk or run in a direction tangential to wheel  132 , or attach flexible member free end  149  to the seat post of a bicycle and ride in a direction tangential to wheel  132 . If the direction of linear movement is downward or partially downward, such as if the generator system with the wheel system mounted on a horizontal surface is at the top of a hill, a user will benefit from the gravitational potential energy resulting from their change of elevation combined with the muscle energy associated with their movement such as via bicycling, walking, or running. This resulting combination of muscle energy and gravitational potential energy will then be converted into electrical power that can fast-charge electronic devices. 
     Additional embodiments result from mass  155  being provided by various objects, such as water, stones, or any other massive objects or combinations of massive objects that can be placed in receptacle  156 . Mass  155  could also be part or all of a human&#39;s body weight. If the generator system with the wheel system mounted on a horizontal or vertical surface is on an elevated ledge, for example, and a person steps off the ledge and into the receptacle, gravity acting on their mass would become the energy source for producing electrical power that can fast-charge electronic devices. If the ledge is positioned at the top of a staircase, such as the kind found inside a multi-story dwelling, outside an office building, or leading up to a patio, a person could repetitively ascend the steps, step off the ledge into the receptacle to descend in order to provide electrical power to charge their device, re-ascend the steps, rewind flexible element  150  onto wheel  132 , step into the receptacle to descend in order to provide electrical power to charge their device, and so on. 
     Additional embodiments result from varying the mounting angle of the generator system. In addition to horizontal mounting surface  108  oriented at zero degrees with the horizon, and vertical mounting surface  130  oriented at 90 degrees with the horizon, any mounting surface angle between zero and 360 degrees with the horizon (where angles between 180 and 360 degrees would represent orientations with the mounting surface situated above the generator system) is possible, such as a slanted rooftop or ceiling. 
     Additional embodiments result from means of smoothing capacitance  94  being removed from all embodiments previously described. In its place a buck controller can be used to limit the voltage of the first electrical output to levels appropriate to charge control circuit  78 . 
     Additional embodiments result from charge control circuit  78  being incorporated via means other than charge control PCB  79 . PCB  79  could be modified to allow charge control circuit  78  to deliver higher power output and faster charging speeds as allowed by USB fast-charging standards. 
     Additional embodiments result from varying the operational values of gear ratio  47  and generator  50 . For example, it is possible to use a gear ratio greater than or less than 30:1 or a motor with rated power less than or greater than 40 W watts, rated voltage of less or greater than 24V, or operating speed less or more than 1800 RPM. 
     Additional embodiments result from first rotational element  32  being comprised of something other than shaft  31  and key  34 . Examples of rotational elements that fulfill the function of transferring to a generator rotational energy that can fast-charge a device via USB in the same manner as shaft  31  and key  34  include gears, sprockets, splined shafts, splined hollow cylinders, and belt-driven wheels. 
     Additional embodiments result from gear ratio  47  being provided by a means other than gears, such as differentially sized wheels or sprockets driven by belts or chains. 
     CONCLUSION 
     The portable electricity generator herein described is able to deliver many times more charge power to electronic devices charged via USB than the prior art. It does this by incorporating power electronics allowing it to operate in accordance with USB fast-charging standards. While hand-cranked portable electricity generators described in the prior art require two-handed operation, all embodiments of the portable electricity generator herein described that involve hand cranking allow for one-handed operation. While no portable electricity generators able to charge electronic devices via USB in the prior art are powered by gravitational potential energy, several embodiments of the portable electricity generator herein described are powered by gravitational potential energy. While no electricity generators able to charge electronic devices via USB described in the prior art can combine energy sources, embodiments of the portable electricity generator described herein can operate on a combination of human muscle energy and gravitational potential energy.