Abstract:
A system for capturing and storing electrical energy from irregular limited reciprocal linear movement along a cylinder, such as a shock absorber of a vehicle. A linear generator with electrical coils is wound around the cylinder parallel to the movement of the cylinder or along the cylinder. The electrical current generated by the linear generator can be stored in a battery. The energy from the recoil of a large military gun can also be captured by a linear generator along the barrel of the gun and stored in the battery. A processing device can be included to control the flow of electric energy from the linear generator to the battery. The electrical current can pass through a filter and may be processed by a conditioner to limit the range of voltage generated by the linear generator.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to copending U.S. provisional application entitled, “Linear Generator For Suspension System Energy Capture,” having Ser. No. 60/553,219 filed Mar. 15, 2004, which is entirely incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a linear generator for generating electricity from the irregular movement of apparatus, vehicles, such as the up and down movement of vehicles in response to changes in the terrain over which the vehicles travel, and from the recoil of large weapons which can be captured by a linear generator and stored in batteries for future use. 
         [0004]    2. Background of the Invention 
         [0005]    There is a great deal of energy that is not profitably used because we have not had satisfactory systems for capturing and using the energy. For example, the energy that is generated by the spring and shock absorber damping of vehicles is not profitably used. This energy is basically converted to heat within the shock absorber damping system. The recoil from the firing of a large gun on a gun carriage, tank or other military vehicle is also not profitably used. This energy is hard to capture because the movement is an irregular movement. If this energy could be captured and converted into electricity, it could be readily stored in batteries for future use. 
         [0006]    A number of hybrid vehicles have been introduced to the market in the last few years. These hybrid vehicles combine an internal combustion engine with an electric motor to power the vehicle. The internal combustion engine can either power the vehicle or use any surplus power to charge the batteries which are used for running the electric motor or motors to power the vehicle. Hybrid vehicles are making an impact in the automobile market. They are also being used on the heavy vehicles and hold a lot of promise for use on heavy military vehicles that frequently travel off-road. Hybrid vehicles improve the fuel efficiency by using any surplus power developed by the internal combustion engine and also during braking to generate electricity to charge the batteries for powering the electric motor to drive the vehicle or power other electrical devices. 
         [0007]    There is a keen interest in making the hybrid vehicles even more efficient. Heavy off-road vehicles, such as heavy military equipment like tanks and armored personnel carriers, have considerable energy that is lost in the up and down movement of the vehicle over rough terrain or even on relatively smooth terrain. These movements can be dampened by shock absorbers and springs, but the energy generated is not put to any practical use. In fact, the energy produces heat which is undesirable. This is also true of vehicles such as tanks and self-propelled guns where a lot of energy is also created in the recoil of the gun when it is fired. The efficiency of these heavy vehicles could be improved if the up and down energy of the vehicle moving over terrain with bumps could be captured and stored in batteries for future use. This would be particularly useful to heavy military vehicles that travel off road and consequently generate a great deal of energy by up and down movement over bumps and irregularities in the terrain. Improving the efficiency of these heavy military vehicles is important, as it is frequently difficult to supply these vehicles with fuel during combat. 
       SUMMARY OF THE INVENTION 
       [0008]    This invention provides a system for capturing and storing electrical energy from the irregular or sporadic limited reciprocal linear movement along the length of a cylinder, which could be a shock absorber or the barrel of a large military gun. A linear generator with electrical coils is wound around the length of the cylinder parallel to the movement of the cylinder or movement of a rod and piston in the cylinder. The linear generator is capable of converting a large portion of the energy of movement along the cylinder into electricity. This electricity can be stored in a battery or used for powering electric motors that drive the vehicle or other appliances. The current from the linear generator can be passed through filters that may include a bridge rectifier circuit and a capacitor before it reaches the battery. A processing device can be provided to shut the current the off and on or to divert it from the battery for another use. 
         [0009]    Because a vehicle on rough terrain may encounter both large bumps and small bumps, it is preferable that the shock absorber assembly has a primary linear generator and two secondary linear generators. The primary linear generator is designed to convert the energy from a large bump and the two secondary linear generators are designed to produce current from small bumps. As the electrical current produced by the linear shock absorber that passes through a filter is irregular in voltage, the current can be passed through a conditioner which is also controlled by a processing device in the vehicle. This conditioner can limit the range of the voltage that is conducted to the battery. 
         [0010]    Of course, all four wheels of the vehicle can have linear generator shock absorbers, with either a single shock absorber for a wheel or a primary and two secondary shock absorbers per wheel. 
         [0011]    The processing device may use a program for the conditioner and the off and on switches from the various linear generators to achieve the desired charge of the battery and powering of any other motor or electric appliance. 
         [0012]    Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0014]      FIG. 1  is a perspective view of a shock absorber assembly for a vehicle in which a linear generator replaces the conventional shock absorber. 
           [0015]      FIG. 2  is cross sectional view of the linear generator shock absorber of  FIG. 1 . 
           [0016]      FIG. 3  is a graph showing the voltage variation over distance traveled by the vehicle in which the linear generator shock absorber is installed. 
           [0017]      FIG. 4  is a cross section of the linear generator shock absorber with a primary and two secondary linear generators. 
           [0018]      FIG. 5  is a graph showing the variation in the voltage supplied by a linear generator and processed through a power conditioner to limit the voltage variation. 
           [0019]      FIG. 6  is a circuit diagram for processing the electricity generated by a single linear generator shock absorber as shown in  FIGS. 1 and 2 . 
           [0020]      FIG. 7  is a circuit diagram for a shock absorber assembly that has a primary linear generator and two secondary linear generators as illustrated in  FIG. 4 . 
           [0021]      FIG. 8  is a circuit diagram for four separate linear generator shock absorbers as would be found on a four wheel vehicle. 
           [0022]      FIG. 9  is a perspective view of the self-propelled howitzer which has a primary linear generator for generating current from the recoil of the gun. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    It has been found that a linear generator can be used to capture the energy that otherwise is not profitably utilized in situations involving the irregular movement of a cylinder, such as a shock absorber on a vehicle or a large gun barrel during recoil. One application where this invention is particularly promising is in respect to replacing the spring and shock absorber damping system on a vehicle with linear generation equipment. The linear generator is designed so that the reactive motion of the suspension system is dampened by the back-electromotive force in the generator. 
         [0024]      FIG. 1  shows a linear generator shock absorber having replaced the standard shock absorber in a vehicle. This shock absorber assembly  10  has a linear generator shock absorber  12  which is attached to the axle  14  of the vehicle to which a wheel W is attached. The shock absorber assembly  12  is attached to the frame  16  of the vehicle by a strut  18 . The strut  18  is attached to the frame  16  by a nut and bolt  40  fastening system. The strut  18  is attached to the linear generator shock absorber  12  by bolts  20  secured by nuts  22 , with the bolts  20  extending through plate  24  which is attached to rod  26  which extends into the linear generator shock absorber  12  and is attached to a piston (not shown). The linear generator shock absorber  12  is attached to the axle  14  by one or more bolts (not shown). A dust cover  28  covers these bolts. This shock absorber assembly  10  utilizes a spring  32  that is attached to the axle  14  by a clamp  34  secured by nuts  36 . A plate  38  connects the two clamps  34  together. It should be realized that the linear generator shock absorber  12  could replace the spring  32  entirely or only replace the standard shock absorber. A bumper  30  is provided to prevent excessive movement of the wheel on the vehicle in relation to the frame. 
         [0025]    As the vehicle on which the linear generator shock absorber  12  is installed moves over terrain with irregularities, the wheel attached to shock absorber assembly  10  moves up and down. The linear generator generates electricity with this movement. The electricity can be supplied to a battery or otherwise used to supply electricity to certain electrical appliances. This linear generator shock absorber  12  can be designed to fit into the space normally taken up by a conventional shock absorber component on a vehicle. In the case of a hybrid vehicle with electric motors supplying a portion of the power to the wheels, the linear generator shock absorber can supply some of that power to those electric motors. 
         [0026]      FIG. 2  is cross sectional view of the linear generator shock absorber  12  of  FIG. 1 . The linear generator shock absorber  12  includes a cylinder  9 , electrical coils  5  and piston  11 . The cylinder  9  has a chamber  13  through which the piston  11  travels. This chamber  13  may or may not be filled with a dampening fluid. The cylinder  9  is a portion of a shock absorber for a vehicle which is designed to absorb the shocks transmitted when the vehicle is moving on terrain with irregularities in the surface. The electrical coils  5  are wound around at least a substantial portion of the length of the cylinder  9  parallel to the movement of the piston  11  along the cylinder  9 . The electrical coils  5  are supported in a stationary position in relation to the movement along the cylinder  9 . More specifically, the electrical coils  5  are supported between inner wall  7  and outer wall  3  of the cylinder  9 . 
         [0027]    The piston  11  is attached to a piston shaft  26 . The piston  11  moves along the length of the cylinder  9  as the vehicle moves on the terrain, and generates electricity with this movement. The piston shaft  26  can be connected to a damping device (not shown) that can dampen the movement of the piston  11  along the cylinder  9 . The linear generator shock absorber  12  converts at least a substantial portion of the energy of the movement of the piston  11  along the cylinder  9  into electricity. The converted energy is operatively output to the battery via electrical connection  15 . 
         [0028]      FIG. 3  is a graph showing the voltage variation over distance traveled by the vehicle in which the linear generator shock absorber is installed.  FIG. 3  shows the irregular energy generated by the shock absorber due to the “bumpy” terrain. A power conditioner (not shown) conditions the irregular energy to a controlled energy that cain have sinusoidal characteristics as shown in  FIG. 5 . The power conditioner can include a capacitor that is charged by the signal/pattern of the irregular energy. The capacitor stores the energy in a form that can be used by most any power management system. As the capacitor is being charged, a processing device determines whether the capacitor has sufficient energy to charge an energy-storing device, e.g., a battery. In short, the capacitor is a temporary energy “holding tank” that stores energy to be released to a battery based on the determination of the processing device. In addition, since the capacitor is DC, and many forms of power storage use DC systems, the output of the capacitor can be tailored into any form that is required by the end using system. For example, a switching regulator can be used to transform the voltage of the capacitor to match the voltage of the end using system, or to be used to charge a battery. In another example, a switching system can use the energy to generate 50, 60, or 400 hertz power for the end using system. By filtering and conversion, the irregular energy can be transformed to charge a battery or for charging an array of capacitors that would provide power output for short duration. 
         [0029]      FIG. 4  is a cross section of the linear generator shock absorber with a primary and two secondary linear generators. The linear generator shock absorber includes the primary linear generator  12  which has similar electrical components described above in relation to  FIG. 2  and therefore includes a cylinder  9 , piston  11 , and electrical coils  5 . The two secondary linear generators  31  are similar to the primary linear generator  12  and therefore include chambers  23 , cylinders  29 , pistons  25 , and electrical coils  33 . In each of the secondary linear generators  31 , the electrical coils  33  are wound around at least a substantial portion of the length of the cylinder  29  parallel to the movement of the piston  25  along the cylinder  29 . The electrical coils  33  are supported in a stationary position in relation to the movement of the piston  25  along the cylinder  29 . More specifically, the electrical coils  33  are supported between inner wall  21  and outer wall  19  of the cylinder  29 . 
         [0030]    The piston  25  is attached to a piston shaft  27 . The piston  25  moves along the length of the cylinder  29  as the vehicle moves on the terrain, and generates electricity with this movement. The piston shaft  27  can be connected to a damping device (not shown) that can dampen the movement of the piston  25  along the cylinders  29 . The two secondary linear generator shock absorbers  31  convert at least a substantial portion of the energy of the movement of the piston  25  along the cylinder  29  into electricity. The converted energy is operatively output to the battery via electrical connection  35 . 
         [0031]      FIG. 6  is a circuit diagram for processing the electricity generated by a single linear generator shock absorber  12  as shown in  FIGS. 1 and 2 . The single linear generator shock absorber  60  is coupled to a filter  61  that filters converted energy from the linear generator shock absorber  60  and operatively outputs filtered energy to the battery  70 . The filter  61  includes, for example, a bridge rectifier circuit  62  and a capacitor  64 . Other filters can be used such as a RC filter. The filtered energy from the filter  61  is received by a switch  66  that connects or disconnects the linear generator  60  to the battery  70 . A processing device  68  is connected to the switch  66  and is capable of sensing the filtered energy from the filter  61 . The processing device  68  is also capable of determining whether to connect or disconnect the linear generator  60  to the battery  70  based upon the filtered energy from the filter  61 . In addition, the processing device  68  is capable of controlling the switch  66  to connect or disconnect the linear generator  60  to the battery  70 . 
         [0032]    The processing device of  68  may disconnect the linear generator  60  from the battery  70  when the battery is fully charged. It may also disconnect the linear generator  60  from the battery  70  and attach it to another appliance or electric motor, such as a motor for driving the vehicle. The processing device can also be programmed to connect the linear generator  60  to the battery  70  when the battery  70  reaches a certain state of discharge. 
         [0033]      FIG. 7  is a circuit diagram for a shock absorber assembly that has a primary linear generator and two secondary linear generators as illustrated in  FIG. 4 . Similar to the system described above in relation to  FIG. 6 , the primary linear generator  72  is coupled to a first filter  75  that filters converted energy from the primary linear generator  72  and operatively outputs filtered energy to the battery  98 . The first filter  75  includes, for example, a bridge rectifier circuit  78  and a capacitor  84 . The filtered energy from the first filter  75  is received by a first switch  90  that connects or disconnects the linear generator  72  to the battery  98 . 
         [0034]    A first secondary linear generator  74  is connected to a second filter  85 , which includes, for example, a bridge rectifier circuit  80  and a capacitor  86 . The second filter  85  is connected to a second switch  92  that connects or disconnects the first secondary linear generator  74  to the battery  98 . A second secondary linear generator  76  is connected to a third filter  87 , which includes, for example, a bridge rectifier circuit  82  and a capacitor  88 . The third filter  87  is connected to a third switch  94  that connects or disconnects the second secondary linear generator  76  to the battery  98 . The processing device  96  is connected to the first, second, and third switches  90 ,  92 ,  94 , and is capable of sensing first, second, and third filtered energy from the first, second, and third filters  75 ,  85 ,  87 , respectively. The processing device  96  is also capable of determining whether to connect or disconnect the primary linear generator  72  and the first and second secondary linear generators  74 ,  76  to the battery  98  based upon the first, second, and third filtered energy from the first, second, and third filters  75 ,  85 ,  87 , respectively. In addition, the processing device  96  is capable of controlling the first, second, and third switches  90 ,  92 ,  94  to connect or disconnect the primary linear generator  72  and the first and second secondary linear generators  74 ,  76  to the battery  98 . 
         [0035]    The processing device  96  can be programmed to connect to the primary linear generator  72  to the battery  98  when a large bump in the road is encountered. It may be necessary to have a sensor on the shock absorber to anticipate a big bump and to send that message to the processing device  96 . For small bumps in the road, the first and second secondary linear generators  74  and  76  are more appropriately used. Obviously, the processing device  96  can be programmed to best meet the electrical needs of the vehicle. 
         [0036]      FIG. 8  is a circuit diagram for four separate linear generator shock absorbers as would be found on a four wheel vehicle. The circuit diagram in  FIG. 8  includes similar electrical components described above in relation to  FIG. 6  and therefore includes a linear generator shock absorber  60 , filter  61 , capacitor  64 , switch  66 , and battery  70 . The circuit diagram of  FIG. 8  further includes a second linear generator shock absorber  102  that is connected to a second filter  111 , which includes, for example, a bridge rectifier circuit  110  and a capacitor  118 . The second filter  111  is connected to a second switch  126  that connects or disconnects the second linear generator shock absorber  102  to the battery  70 . 
         [0037]    A third linear generator shock absorber  104  is connected to a third filter  113 , which include, for example, a bridge rectifier circuit  112  and a capacitor  120 . The third filter  113  is connected to a third switch  128  that connects or disconnects the third linear generator shock absorber  104  to the battery  70 . A fourth linear generator shock absorber  106  is connected to a fourth filter  115 , which include, for example, a bridge rectifier circuit  114  and a capacitor  122 . The fourth filter  115  is connected to a fourth switch  130  that connects or disconnects the fourth linear generator shock absorber  106  to the battery  70 . 
         [0038]    A processing device  132  is connected to the first, second, third, and fourth switches  66 ,  126 ,  128 ,  130 , and is capable of sensing a first, second, third, and fourth filtered energy from the first, second, third, and fourth filters  61 ,  111 ,  113 ,  115 , respectively. The processing device  132  is also capable of determining whether to connect or disconnect the linear generator shock absorbers  60 ,  102 ,  104 ,  106  to the battery  70  based upon the first, second, third, and fourth filtered energy from the first, second, third and fourth filters  61 ,  111 ,  113 ,  115 . In addition, the processing device  132  is capable of controlling the first, second, third, and fourth switches  66 ,  126 ,  128 ,  130  to connect or disconnect the linear generator shock absorbers  60 ,  102 ,  104 ,  106  to the battery  70 . 
         [0039]    It should be realized that each of the shock absorbers  60 ,  102 ,  104 , and  106  could have a secondary shock absorber as illustrated in  FIG. 7 . The processing device  132  in  FIG. 8  can determine whether to permit current flow from a primary or secondary shock absorber to the battery  70 . The processing device can also be programmed so that only some of the shock absorbers are supplying energy to the battery. The processing device  132  can also direct the flow of current to any electric motor for powering the vehicle or to another electrical appliance. 
         [0040]    It should be noted that the processing devices  68 ,  96 ,  132  are connected to the battery via the switches and are capable of determining the state of charge (SOC) of the battery and/or the battery charge acceptance (BCA) of the battery, and then charging the battery in a manner which is responsive to the determined SOC/BCA of the battery. This is disclosed in U.S. Pat. No. 6,094,033, to Ding et al., and U.S. Pat. No. 6,229,285, to Ding, which are all herein incorporated by reference. 
         [0041]      FIG. 9  illustrates a self-propelled howitzer  100 . This howitzer has a barrel  102  which recoils each time the gun is fired. As in the case of the shock absorber shown in  FIG. 1 , coils can be wrapped around a gun sleeve  104  to form a linear generator for generating electric power for the self-propelled gun when it is fired. This replaces, in whole or part, the hydraulic dampening arrangement in the howitzer for absorbing the recoil. 
         [0042]    The linear generator of this invention can be used to capture the energy expended in the recoil of the barrel of a large gun when fired. The electric coils can be wrapped around a portion of the barrel and held in a stationary position on the gun carriage while the barrel recoils. The linear generator can generate electricity from the recoil for supplying the electrical needs connected with the operation of the large gun. 
         [0043]    It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.