Abstract:
A method of utilizing potential energy at a worksite comprising providing an energy storage machine including an energy storage system at a first rendezvous height above a working area, coupling the energy storage machine to a first work machine, generating energy while commuting the energy storage machine and first work machine down the first height, storing the generated energy in the energy storage system and decoupling the energy storage machine and the first work machine at a second rendezvous point adjacent to the working area.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to machines that include an electric motor, and more particularly to an off-highway electric-drive machine and battery trailer system and method of using the same. 
       BACKGROUND 
       [0002]    Various machines utilize an electric motor to provide motive-force to propel the machine. Depending upon the application and configuration, the electric motor may be the primary supplier of motive-force, such as in a purely electric machine, or may act as a supplemental supplier of motive-force, as in certain types of hybrid-electric machines. The electric motor requires energy provided by a power source in order to generate the motive-force to propel the machine. The power source may vary from application to application, examples of which include: a battery-only power source in which the electric motor draws power only from a battery; an engine and generator combination in which a generator transforms mechanical energy from an engine into electrical energy to be used by the electric motor; and various combinations thereof. 
         [0003]    United States Patent Publication No. 2010/0147604 discloses a plug-in electric automobile having a trunk section modified to accept an auxiliary battery disposed on a separable assembly. U.S. Pat. No. 5,559,420 discloses an electric supply unit trailer that carries auxiliary batteries and may be towed behind an electric machine for supplying power to the electric machine during driving operations. U.S. Pat. No. 6,973,880 discloses an off-highway machine utilizing fraction motors and generating and storing power from regenerative braking in batteries located on/within the off-highway machine. However, all of the above mentioned applications have drawbacks regarding the weight and complexity of the associated batteries. The present disclosure seeks to cure such deficiencies. 
       SUMMARY 
       [0004]    In one aspect, a method for utilizing potential energy at a worksite includes; providing an energy storage machine including an energy storage system at a first rendezvous point at a first height above a working area, coupling the energy storage machine to a first work machine, generating energy while commuting the energy storage machine and first work machine down the first height, storing the generated energy in the energy storage system, and decoupling the energy storage machine and the first work machine at a second rendezvous point adjacent to the working area. 
         [0005]    In another aspect, an energy conversion, storage and utilization system includes; a worksite including a first rendezvous point and a second rendezvous point disposed at a first height below the first rendezvous point, at least one energy storage machine which includes a regenerative braking system that generates energy while commuting the energy storage machine from the first area to the second area down the first height, and an energy storage system that stores the generated energy, and at least one work machine which is coupled to at least one of the at least one energy storage machines, wherein the at least one energy storage machine and the at least one work machine are coupled at the first rendezvous point and decoupled at the second rendezvous point. 
         [0006]    In another aspect, an energy storage machine includes; a chassis, a motive assembly connected to the chassis, an energy storage system and a coupler configured for connection with a work machine, wherein the coupler mechanically couples the energy storage machine to the work machine and the coupler provides an energy transfer path between the work machine and the energy storage system. 
         [0007]    Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram of an exemplary embodiment of a work machine; 
           [0009]      FIG. 2  is a schematic diagram of an exemplary embodiment of an energy storage machine; 
           [0010]      FIG. 3  is a schematic diagram of a configuration wherein the work machine of  FIG. 1  and the energy storage machine of  FIG. 2  are coupled; 
           [0011]      FIG. 4  is a schematic diagram of an exemplary embodiment of a worksite; 
           [0012]      FIG. 5  is a schematic diagram of a first step in an exemplary embodiment of a method of utilizing the energy storage machine to store energy; 
           [0013]      FIG. 6  is a schematic diagram of a second step in an exemplary embodiment of a method of utilizing the energy storage machine to store energy; 
           [0014]      FIG. 7  is a schematic diagram of a third step in an exemplary embodiment of a method of utilizing the energy storage machine to store energy; 
           [0015]      FIG. 8  is a schematic diagram of a fourth step in an exemplary embodiment of a method of utilizing the energy storage machine to store energy; 
           [0016]      FIG. 9  is a schematic diagram of a fifth step in an exemplary embodiment of a method of utilizing the energy storage machine to store energy; 
           [0017]      FIG. 10  is a schematic diagram of a first step in an exemplary embodiment of a method of utilizing the energy storage machine to expend energy; 
           [0018]      FIG. 11  is a schematic diagram of a second step in an exemplary embodiment of a method of utilizing the energy storage machine to expend energy; 
           [0019]      FIG. 12  is a schematic diagram of a third step in an exemplary embodiment of a method of utilizing the energy storage machine to expend energy; 
           [0020]      FIG. 13  is a schematic diagram of a fourth step in an exemplary embodiment of a method of utilizing the energy storage machine to expend energy; and 
           [0021]      FIG. 14  is a schematic diagram of a fifth step in an exemplary embodiment of a method of utilizing the energy storage machine to expend energy. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The present disclosure is directed towards a system and method for utilizing otherwise unused potential energy in a manner that maximizes a machine to battery weight ratio and a machine to battery unit ratio. Specifically, the method provides utilizing a relatively small number of energy storage machines, as compared to work machines, strategically positioned at energy generation and energy expenditure areas within a worksite. The energy storage machines may be coupled to work machines to capture energy generated by the work machines at energy generation sites and may be coupled to work machines to expend energy at energy expenditure areas. The energy storage machines may be de-coupled from the work machines when the work machines reach areas within the worksite where excess energy expenditure/generation does not occur. 
         [0023]      FIG. 1  illustrates an exemplary embodiment of a work machine  100 , one exemplary embodiment of which may be an off-highway truck. In another exemplary embodiment, the work machine  100  may be configured for an underground mine site environment. In the present embodiment, the work machine  100  includes a chassis  110  and a dump body  120  connected to the chassis  110 . In one exemplary embodiment, the dump body  120  may be movably connected to the chassis  110  via a hinge (not shown) or other assembly in order to allow the dump body  120  to be angled such that the contents thereof may be deposited outside of the work machine  100 . Alternative exemplary embodiments include configurations wherein the dump body  120  includes alternative means for emptying the contents thereof, e.g., a controllable opening disposed in a bottom of the dump body  120  and extending through the chassis  110  such that the contents of the dump body  120  may be dropped directly underneath the work machine  100 . Alternative embodiments also include configurations wherein the dump body  120  is omitted. 
         [0024]    In the present exemplary embodiment, the work machine  100  also includes a set of wheels  130  that are rotatably connected to the chassis  110 . Alternative exemplary embodiments include configurations where the wheels  130  may be modified or replaced with a tracked assembly (not shown) or various other similar devices. 
         [0025]    In order to provide motive force to the wheels  130 , the work machine  100  includes a propulsion system  140 . In the present exemplary embodiment, the propulsion system  140  includes an internal combustion engine (“ICE”)  142  that converts chemical energy into mechanical energy via combustion of a fuel, e.g., diesel fuel. In the illustrated embodiment, the mechanical energy produced by the ICE  142  is converted to electrical energy via a generator  144 . The generator  144  is not particularly limited and may be any of several well-known mechanical-to-electrical energy conversion devices, e.g., an alternator. Electrical energy produced by the generator  144  is then passed via wiring  146  to at least one electric traction motor  148  that provides motive power to at least one of the wheels  130 . In the illustrated embodiment, the work machine  100  includes an electric traction motor  148  on each of the wheels  130  in an all-wheel drive configuration. The at least one electric traction motor  148  is configured to provide a regenerative braking ability as will be discussed in more detail below. 
         [0026]    Although one embodiment of providing motive force to the wheels  130  has been discussed above with respect to an all-electric drive configuration, the present disclosure is not limited thereto. The disclosure may equally relate to a hybrid drive configuration wherein a mechanical linkage (not shown) located between the ICE  142  and the wheels  130  also provides motive force in addition to the electric traction motor  148  among various other configurations. 
         [0027]    In addition to the above components, the propulsion system  140  also includes a first connection assembly  150  for electrical connection to an energy storage machine  200 . In one exemplary embodiment, the energy storage machine  200  may be a battery trailer. In one exemplary embodiment, the first connection assembly  150  provides both an electrical connection and a mechanical connection to the energy storage machine  200 . Although the present disclosure is not limited thereto, the first connection assembly  150  may include any one of a mechanical Janney-type coupler (not shown), a tow hitch, an induction-type coupler, a magnetic-type coupler, a power take off (“PTO”) unit and yoke (not shown), and a pintle hook and lunette ring and a separate electrical connection (not shown). In another exemplary embodiment, the mechanism that provides the mechanical coupling may also provide the electrical coupling. The first connection assembly  150  is electrically connected to the at least one electric traction motor  148 . Exemplary embodiments include configurations wherein the first connection assembly  150  is directly electrically connected to the at least one electric traction motor  148  and configurations wherein the first connection assembly  150  is electrically connected to the at least one electric fraction motor  148  via various electrical signal regulating apparatus, e.g., a transformer (not shown), a voltage regulator (not shown), a voltage inverter/converter (not shown), etc. 
         [0028]      FIG. 2  illustrates an exemplary embodiment of the energy storage machine  200 . The embodiment of the energy storage machine  200  includes a chassis  210  rotatably connected to wheels  230 . In the illustrated embodiment, the energy storage machine  200  includes wheels  230  on at least two separate axles (not shown); however, alternative embodiments include motive assembly configurations wherein only a single axle (not shown) may be used, configurations wherein more than two axles (not shown) may be used and even configurations wherein no axles (not shown) may be used, such as in a spherical wheel arrangement. 
         [0029]    The energy storage machine  200  also includes an energy storage device, which in this particular embodiment is a battery  240 . In one exemplary embodiment, the battery  240  is connected via wiring  246  to a second connection assembly  250 . Cost, weight, complexity and maintainability of the energy storage machine  200  are especially important given that the energy storage machine  200  may be used in rugged and remote environments. Therefore, a simple configuration of the energy storage machine  200  may be critical to commercial success of any system implementing the same. 
         [0030]    The second connection assembly  250  electrically connects the energy storage machine  200  and the work machine  100 . In one exemplary embodiment, the second connection assembly  250 , together with the first connection assembly  150 , provides both an electrical connection and a mechanical connection to the work machine  100 . In one exemplary embodiment, the second connection assembly  250  may include any one of a mechanical Janney-type coupler (not shown), a tow hitch (not shown), a PTO unit and yoke connection (not shown), and a pintle hook and lunette ring and a separate electrical connection (not shown). In another exemplary embodiment, the mechanism that provides the mechanical coupling also provides the electrical coupling. The second connection assembly  250  is electrically connected to the at least one electric traction motor  148  via the first connection assembly  150 . In one exemplary embodiment wherein the first connection assembly  150  and the second connection assembly  250  include PTO units, the PTO unit and yoke associated with the work machine  100  may include a splined driveshaft (not shown) which operates an electrical generator (not shown) in the energy storage machine  200 . 
         [0031]      FIG. 3  illustrates an exemplary embodiment of a coupled work machine  100  and energy storage machine  200 . As shown in  FIG. 3 , the first and second connection assemblies  150  and  250  provide a mechanical linkage between the two machines and also provides an electrical connection between the battery  240  and the at least one electric traction motor  148  on the work machine. In this configuration, the battery  240  may store energy generated by the at least one traction motor  148 , e.g., energy generated by the at least one electric traction motor  148  via regenerative braking In addition, in this configuration, the battery  240  may deliver stored energy to the at least one electric traction motor  148  in addition to, or as an alternative to, the energy generated by the generator  144 , e.g., in a hill-climbing application as will be discussed in more detail below. 
       INDUSTRIAL APPLICABILITY 
       [0032]    A method of utilizing the energy storage machine  200  to store potential energy and a method of utilizing the energy storage machine  200  to expend stored energy are disclosed below with respect to  FIGS. 4-14 . As described in more detail with respect to  FIGS. 4-14 , the method, and system of components used in the method, converts potential energy into kinetic energy and then into energy stored onboard the energy storage machine  200  which may be used later. In one embodiment, the method/system converts mechanical energy to electrical energy, which may then later be converted back into mechanical energy. This is in contrast to the prior art, which teaches the conversion of potential energy into kinetic energy and then into thermal energy, such as in mechanical braking applications where brake pads and disks rub together to slow a machine, or in a machine that uses regenerative braking to generate electricity that is then expended to thermal energy via a resistor array or other apparatus. The present disclosure provides a means for utilizing the energy that the prior art radiates to the environment as unused heat. 
         [0033]      FIG. 4  is a schematic diagram of an exemplary embodiment of a worksite  300 . In the present embodiment, the worksite  300  includes a working area, e.g., an excavation zone  310 , and a pathway  320  leading to the excavation zone  310  from an outside, e.g., an unloading zone (not shown). The excavation zone  310  may include an excavator  330  for depositing a load  340  of material excavated from a working face  350  into the working machine  100 . The pathway  320  descends from the outside to the excavation zone  310  over a vertical distance h 1 . The pathway  320  may include various inclined and level surfaces as illustrated in  FIG. 4 , or may include a single inclined surface (as described in more detail with respect to  FIG. 5 ). 
         [0034]    In operation, a work machine  100  begins a descent to the excavation zone  310  at point A. The work machine  100  descends along the pathway  320  at points B and D to arrive at the excavation zone  310 . Along the descent, the machine converts the potential energy it had at point A to kinetic energy. The kinetic energy must be maintained within a predetermined range in order for the work machine  100  to maintain safe operation. The potential energy of the work machine  100  is a function of the position of the work machine  100  within the Earth&#39;s gravitational field as described in equation 1: 
         [0000]      Potential Energy= m*g*h    &lt;Equation 1&gt;
 
         [0000]    wherein “m” is the mass of the work machine  100 , “g” is the acceleration due to gravity, and “h” is the altitude of the work machine  100  within the gravitation field. Thus, as h decreases, the potential energy of the work machine  100  also decreases. That is, if a height h 2  were half a height h 1 , the potential energy as measured at h 2  would be half the potential energy at height h 1 . Similarly, at the excavation zone  310 , all of the potential energy in the system has been converted to other forms of energy through the conservation of energy. 
         [0035]    The decrease in potential energy is converted to kinetic energy as described in equation 2: 
         [0000]      Kinetic Energy=0.5 *m*v̂ 2   &lt;Equation 2&gt;
 
         [0000]    wherein “v” is the velocity of the work machine  100 . Thus, if left unchecked, the change in potential energy would rapidly lead to a large increase in velocity of the work machine  100  along the pathway  320 . However, the work machine  100  includes a system for maintaining the velocity of the work machine  100 , i.e., a braking system, as will be discussed in greater detail below. 
         [0036]    The work machine  100  receives the load  340  at point C in the excavation zone  310 . The load  340  must then be taken away from the excavation zone  310  to the outside, e.g., to the unloading zone (not shown). The work machine  100  provides a motive force to commute up the pathway  320  through points D and B. Essentially, the work machine  100  converts chemical energy stored in its fuel, e.g., diesel fuel, into kinetic energy via the propulsion system  140 . Once the work machine  100  arrives at point A, it again has a large potential energy relative to the starting position at the excavation zone  310 . The present disclosure provides a method and system for utilizing potential energy converted during the descent to the excavation zone  310  and to decrease the amount of chemical energy required to return the work machine  100  to the unloading zone. The system and method will be described in more detail below with respect to  FIGS. 5-14 . 
         [0037]      FIG. 5  is a schematic diagram of a first step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to store energy. As illustrated in  FIG. 5 , the work machine  100  arrives at a first rendezvous point R 1  where the energy storage machine  200  is waiting for coupling. Both the work machine  100  and the energy storage machine  200  are disposed at a height “h 3 ” above the excavation zone  310 . The pathway  320  has been simplified in this example for illustrative purposes only. At this stage in the method, the work machine  100  and the energy storage machine  200  are not mechanically or electrically coupled. 
         [0038]      FIG. 6  is a schematic diagram of a second step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to store energy. As illustrated in  FIG. 6 , the work machine  100  and the energy storage machine  200  are coupled, both mechanically and electrically at the first rendezvous point R 1 . Embodiments include configurations where a driver of the work machine  100  or other personnel performs the coupling. Embodiments also include configurations wherein the work machine  100  or the energy storage machine  200  include mechanisms for automatically performing the coupling process without user interaction. Such automated systems may utilize radar, global positioning system (“GPS”) information, radio frequency identification (“RFID”) or various other locating and navigating schema for performing the coupling. Embodiments include configurations wherein the work machine  100  and the energy storage machine  200  are in motion at the time of coupling. 
         [0039]      FIG. 7  is a schematic diagram of a third step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to store energy. As the work machine  100  and energy storage machine  200  commute down the inclined portion of the pathway  320 , a braking force is applied in order to prevent unwanted acceleration. That is, as potential energy is converted to kinetic energy, the braking force is applied to prevent velocity from increasing beyond a predetermined rate. In the present exemplary embodiment, the braking force may be at least partially applied via regenerative braking utilizing the at least one traction motor  148  in the work machine  100 . 
         [0040]    As used herein, regenerative braking applies to a control scheme where the at least one traction motor  148  of the work machine  100  is operated to generate electricity from a rotation of the wheels  130 . Essentially, the regenerative braking functions substantially oppositely to the operation of providing motive force to the wheels  130 ; rather than converting electricity to provide a motive force, a motive force is converted to electricity. 
         [0041]    The electricity generated by the above method is stored in the energy storage machine  200 . The electricity may be transferred from the work machine  100  to the energy storage machine  200  via the connection assemblies  150  and  250 . 
         [0042]      FIG. 8  is a schematic diagram of a fourth step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to store energy. As illustrated in  FIG. 8 , the work machine  100  and energy storage machine  200  reach a second rendezvous point R 2  that is substantially at a same height as the excavation zone  310 . In this embodiment, the height of the second rendezvous point R 2  is substantially less than the first rendezvous point R 1  by a distance equal to h 3 , and at least a fraction of the differences in potential energy of the work machine  100  and the energy storage machine  200  combination at the first rendezvous point R 1  and the second rendezvous point R 2  has been converted to electrical energy. At this point the work machine  100  and the energy storage machine  200  are still mechanically and electrically coupled. The battery  240  of the energy storage machine  200  has been at least partially charged by the regenerative braking process described above. 
         [0043]      FIG. 9  is a schematic diagram of a fifth step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to store energy. As illustrated in  FIG. 9 , the work machine  100  continues to commute to the excavation zone  310  while the energy storage machine  200  remains at the second rendezvous point R 2 . Embodiments include configurations wherein the work machine  100  and the energy storage machine  200  are in motion at the time of decoupling. 
         [0044]      FIG. 10  is a schematic diagram of a first step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to expend energy. As illustrated in  FIG. 10 , the work machine  100  arrives at the second rendezvous point R 2  with a load  340 . At this point, the work machine  100  and the energy storage machine  200  are not mechanically or electrically coupled. However, the battery  240  of the energy storage machine  200  is at least partially charged by the trip down the pathway  320 . In the embodiment wherein the energy storage machine  200  includes solar panels disposed thereon, the battery  240  may also have been charged via photonic energy. Alternatively, or in addition to the solar panels, the energy storage machine  200  may be connected to an electrical grid for charging or discharging at either rendezvous point R 1  or R 2 . 
         [0045]      FIG. 11  is a schematic diagram of a second step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to expend energy. As illustrated in  FIG. 11 , the work machine  100  and the energy storage machine  200  are coupled, both mechanically and electrically at the second rendezvous point R 2 . Embodiments include configurations where the driver of the work machine  100  or other personnel performs the coupling. Embodiments also include configurations wherein the work machine  100  or the energy storage machine  200  include mechanisms for automatically performing the coupling process without user interaction. Such automated systems may utilize radar, GPS information, RFID or various other locating and navigating schema for performing the coupling. Embodiments include configurations wherein the work machine  100  and the energy storage machine  200  are in motion at the time of coupling. 
         [0046]      FIG. 12  is a schematic diagram of a third step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to expend energy. As illustrated in  FIG. 12 , the work machine  100  and the energy storage machine  200  commute up the inclined portion of the pathway  320 . At this stage in the method, the work machine  100  draws electricity from the battery  240  of the energy storage machine  200  in order to power the at least one traction motor  148  to provide motive force to the wheels  130 . 
         [0047]    The ability of the work machine  100  to draw power from the battery  240  provides an advantage over a system in which the energy storage machine  200  is omitted. The work machine  100  may receive at least a portion of the power required to climb the inclined portion of the pathway  320  from the battery  240 , and therefore the size of the ICE  142  may be decreased by a corresponding degree. That is, rather than the ICE  142  being selected to be of a predetermined size to provide all of the energy generation capabilities required for climbing the inclined portion of the pathway  320 , it may be selected to be of a size to provide only a fraction of the energy generation capabilities required for climbing the inclined portion of the pathway  320 . Alternatively, the same size ICE  142  may be utilized, but run under less strenuous operating conditions and therefore the service lifetime of the ICE  142  may be extended as compared to a system that does not include the energy storage machine  200 . 
         [0048]      FIG. 13  is a schematic diagram of a fourth step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to expend energy. As illustrated in  FIG. 13 , the work machine  100  and energy storage machine  200  reach the first rendezvous point R 1 . At this point the work machine  100  and the energy storage machine  200  are mechanically and electrically coupled. The battery  240  is at least partially depleted due to the energy usage via the work machine  100  during the ascent of the inclined portion of the pathway  320 . 
         [0049]      FIG. 14  is a schematic diagram of a fifth step in an exemplary embodiment of a method of utilizing the energy storage machine  200  to expend energy. As illustrated in  FIG. 14 , the work machine  100  continues to commute to the unloading zone (not shown) while the energy storage machine  200  remains at the first rendezvous point R 1 . Embodiments include configurations wherein the work machine  100  and the energy storage machine  200  are in motion at the time of decoupling. 
         [0050]    While the previous illustrations have shown the energy storage machine  200  as being disposed behind the work machine  100  while in transit, the disclosure is not limited to such an embodiment. Alternative embodiments include configurations wherein the energy storage machine  200  is disposed beside or in front of the work machine  100 . In addition, while the previous illustrations have shown the energy storage machine  200  as being coupled to a single work machine  100 , the disclosure is not limited to such an embodiment. Alternative embodiments include configurations wherein multiple work machines  100  are coupled to a single energy storage machine  200  and configurations wherein multiple energy storage machines  200  are coupled to a single work machine  100 . 
         [0051]    While the use of at least one electric fraction motor  148  and a battery  240  have been described above as potential energy conversion and storage devices, the use of such components is only one possible configuration and alternative energy conversion and storage devices could alternatively be used, e.g., ultra-capacitors, a compressor (not shown) and compressed air storage tank (not shown), a fly-wheel drive (not shown) and flywheel (not shown), etc. 
         [0052]    As described in detail above, the disclosed method and system provide advantages over known configurations. First, the energy storage machine  200  may reduce the operational requirements of the work machine  100  while traveling up the inclined portion of the pathway  320  by providing electric power thereto. Second, the use of the energy storage machine  200  may reduce the weight of the work machine  100  as compared to a configuration wherein a work machine carries its own batteries. That is, as compared to such a configuration, the work machine  100  of the present disclosure is lighter, both at the excavation zone  310  and at the unloading zone (not shown) by at least the weight of the batteries. Finally, because the energy storage machines  200  may be left behind at the rendezvous points R 1  and R 2  while the work machine  100  continues on to its next task, the energy storage machines  200  may be utilized by multiple additional work machines (not shown) while the original work machine  100  completes its task at the excavation zone  310  or unloading zone (not shown). Therefore, because multiple work machines may use a single energy storage machine  200 , the total number of required batteries may be reduced as compared to the configuration in which each work machine carries its own batteries. 
         [0053]    Although the embodiments of this disclosure as described herein may be incorporated without departing from the scope of the following claims, it will be apparent to those skilled in the art that various modifications and variations can be made. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.