Abstract:
A power module is connected to the starter, and generator of a motor vehicle. The power module is housed in a casing made of an insulative material. The power module includes a capacitor and an isolation circuit. The capacitor is connected to the starter when the ignition switch is closed to provide cranking current to the starter. The isolation circuit allows current to flow from the battery to the capacitor, but prevents current flow in the opposite direction. The capacitor is quickly recharged when the engine reaches an increased speed. Therefore, the capacitor is available to provide cranking current to a vehicle even when the vehicle repeatedly stops and starts over a short period of time.

Description:
[0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/484,719, filed Jul. 3, 2003, the disclosure of which is incorporated by reference.  
     
    
     BACKGROUND  
       [0002]     The present invention relates to the field of motor vehicles, and particularly to electrical power systems for motor vehicles.  
         [0003]     During normal operation of a motor vehicle, the battery is used to provide electric current to crank the engine during starting. Once the engine starts and begins running at increased speeds, the vehicle alternator re-charges the battery so the battery will have plenty of charge for the next start. However, in situations where the engine starts and stop many times over a short period of time, drained batteries are often encountered because the alternator does not have sufficient opportunity to re-charge the battery. Drained batteries not only result in the need for jump starts, but also tend to shorten battery life.  
         [0004]     Delivery vehicles are particularly susceptible to drained batteries since the nature of activities associated with delivery vehicles involves repeated stopping and re-starting the vehicle as numerous deliveries are made with only short distances between each stop. As discussed above, the repeated starting and stopping of the delivery vehicle engine subjects the vehicle battery to an unusually high number of discharge cycles. Because the driving time between stops is typically short, there is little time to re-charge the battery during those driving times. Near the end of the day, once a delivery vehicle has made numerous starts and stops, the battery in the vehicle is often drained and cannot provide the current required to crank the engine. The result is that the operator of the delivery vehicle must have the vehicle jump-started or towed to a maintenance facility. Accordingly, it would be advantageous to provide a system that supplements a traditional battery in an automotive vehicle (delivery vehicle or otherwise) so the vehicle battery does not have to provide all the energy for starting the engine.  
       SUMMARY  
       [0005]     In an embodiment, the present invention comprises an electrically conductive isolation device, the electrically conductive isolation device comprising a first connection point and a second connection point, wherein flow of electric current from the first connection point to the second connection point is permitted, and flow of electric current from the second connection point to the first connection point is resisted; means for storing an electric charge, the means for storing an electric charge comprising a positive lead and a negative lead, the means for storing an electric charge having a capacitance of less than 321 farads, the positive lead electrically connected to the second connection point of the electrically conductive isolation device; means for electrically connecting the positive lead to an external electric load; means for electrically connecting the negative lead to ground; and means for electrically connecting the first connection point of the electrically conductive isolation device to a positive terminal of an external DC voltage source.  
         [0006]     In an embodiment, the present invention comprises a starter motor; a generator; a battery, the battery having a positive terminal and a negative terminal, the positive terminal electrically connected to the generator; an electrically conductive isolation device, the electrically conductive isolation device comprising a first connection point and a second connection point, wherein flow of electric current from the first connection point to the second connection point is permitted, and flow of electric current from the second connection point to the first connection point is resisted, the first connection point of the electrically conductive isolation device electrically connected to the positive terminal of the battery, the first connection point of the electrically conductive isolation device electrically connected to the generator; means for storing an electric charge, the means for storing an electric charge comprising a positive lead and a negative lead, the means for storing an electric charge having a capacitance of less than 321 farads, the positive lead electrically connected to the second connection point of the electrically conductive isolation device, the negative lead electrically connected to ground; and means for electrically connecting the positive lead to the starter motor.  
         [0007]     In an embodiment, the present invention comprises means for storing an electric charge, the means for storing an electric charge comprising a positive lead and a negative lead, the negative lead electrically connected to ground; and a rechargeable DC voltage source comprising a positive terminal and a negative terminal, the negative terminal electrically connected to the negative lead, the rechargeable DC voltage source connected in parallel with the means for storing an electric charge, wherein the means for storing an electric charge and the rechargeable DC voltage source are contained in unitary package.  
         [0008]     In an embodiment, the present invention comprises means for storing an electric charge, the means for storing an electric charge comprising a positive lead and a negative lead, the negative lead electrically connected to ground; a rechargeable DC voltage source comprising a positive terminal and a negative terminal, the negative terminal electrically connected to the negative lead; and an electrically conductive isolation device, the electrically conductive isolation device comprising a first connection point and a second connection point, wherein flow of electric current from the first connection point to the second connection point is permitted, and flow of electric current from the second connection point to the first connection point is resisted, the first connection point electrically connected to the positive terminal, the second connection point electrically connected to the positive lead, wherein the means for storing an electric charge, the electrically conductive isolation device, and the rechargeable DC voltage source are contained in unitary package.  
         [0009]     In an embodiment, the present invention comprises a starter motor; a generator; and a unitary power module, the unitary power module comprising (i) an electrically conductive isolation device, the electrically conductive isolation device comprising a first connection point and a second connection point, wherein flow of electric current from the first connection point to the second connection point is permitted, and flow of electric current from the second connection point to the first connection point is resisted, the first connection point of the electrically conductive isolation device electrically connected to the generator, (ii) means for storing an electric charge, the means for storing an electric charge comprising a positive lead and a negative lead, the positive lead electrically connected to the second connection point of the electrically conductive isolation device, the negative lead electrically connected to ground, and (iii) a first battery, the first battery comprising a first positive terminal and a first negative terminal, the first negative terminal electrically connected to the negative lead, the first positive terminal electrically connected to the first connection point of the electrically conductive isolation device.  
         [0010]     In aspects of the foregoing embodiments of the present invention, the electrically conductive isolation device comprises a diode. In aspects of the foregoing embodiments of the present invention, the electrically conductive isolation device comprises an arrangement of electrically interconnected active components. In aspects of the foregoing embodiments of the present invention, the means for storing an electric charge comprises at least one electric double layer capacitor. In aspects of the foregoing embodiments of the present invention further comprises a voltage booster connected in parallel with the electrically conductive isolation device.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The features and advantages of this invention, and the methods of obtaining them, will be more apparent and better understood by reference to the following descriptions of embodiments of the invention, taken in conjunction with the accompanying drawings, wherein:  
         [0012]      FIG. 1  is a block diagram of the connections between the electrical system of a motor vehicle and a power module for motor vehicles according to an embodiment of the present invention;  
         [0013]      FIG. 2  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0014]      FIG. 3A  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0015]      FIG. 3B  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0016]      FIG. 3C  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0017]      FIG. 3D  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0018]      FIG. 3E  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0019]      FIG. 3F  is a schematic showing the connections between the electrical components in an embodiment of a power module according to the present invention;  
         [0020]      FIG. 4  is an elevational view of a power module housing showing the physical arrangement of components in an embodiment of a power module according to the present invention;  
         [0021]      FIG. 5  is a plan view of the power module housing showing the physical arrangement of components in an embodiment of a power module according to the present invention; and  
         [0022]      FIG. 6  is a block diagram of the connections between an embodiment of a power module according to the present invention and the electrical system of a motor vehicle, where the power module has replaced the vehicle&#39;s standard battery.  
     
    
     DESCRIPTION  
       [0023]      FIG. 1  shows a block diagram of an embodiment of a vehicle electrical system having a power module  20  positioned therein. The electrical system includes a starter motor  14  connected to the vehicle engine  12 . The starter motor  14  receives electrical current and rotates to crank the vehicle engine  12 . A generator  16  is also connected to the vehicle engine. Once the engine  12  has started, the generator  16  is driven by the engine  12  and provides electric current to the vehicle electrical system. A vehicle battery  18  is connected to the generator  16  such that the battery can be charged by the electrical current delivered from the generator. Vehicle loads  17  are connected across the battery.  
         [0024]     As shown in  FIG. 1 , an embodiment of the power module  20  is connected to the starter  14 , generator  16 , and vehicle battery  18 . The power module  20  is housed in a nonconductive casing and includes three terminals. The three terminals of the power module  20  include a B(+) terminal  24 , a M(+) terminal  22 , and a Neg(−) terminal (i.e., ground terminal)  26 . The B(+) terminal  24  is connected to the battery terminal of the generator  16  and the positive terminal  19  of the vehicle battery  18 . The M(+) terminal  22  is connected to the battery terminal of the starter motor  14 . A switch (not shown) is located in the electrical connection between the M(+) terminal  22  and the starter  14 , and connection between the M(+) terminal  22  and the starter  14  is made and broken by operation of the switch. (For this reason the connection between the M(+) terminal  22  and the starter is represented by dotted lines in  FIG. 1 .) The switch between the M(+) terminal  22  and the starter  14  is controlled by the ignition switch (not shown) such that the connection between the M(+) terminal  27  and the starter  14  is made when the ignition switch is closed and broken when the ignition switch is open.  
         [0025]     An arrangement of electrical components within an embodiment of the power module  20  is shown in  FIG. 2 . A capacitor  30  is positioned within the module  20  housing with the positive lead/terminal of the capacitor  30  connected to the M(+) terminal  22  and the negative lead/terminal of the capacitor  30  connected to the Neg(−) terminal  26 . The capacitor  30  is an electric double layer capacitor of the type commonly referred to as a “super capacitor.” In an alternative embodiment, the capacitor  30  comprises a bank of capacitors. In one embodiment, the capacitor/capacitor bank has a total capacitance of about 283 farads.  
         [0026]     An isolation circuit (represented by dotted lines  32 ) is also positioned within the housing that contains power module  20 . The isolation circuit  32  comprises a diode  34  connected in series with a fuse  36 . Fuse  36  is optional in this arrangement. The isolation circuit connects the B(+) terminal  24  to the M(+) terminal  22  within the housing of the module  20 . The positioning of the diode  34  in the isolation circuit allows current to flow from the B(+) terminal  24  to the M(+) terminal  22 , but prevents current flow in the opposite direction. This isolates the capacitor  30  from the vehicle battery  18 , and prevents the capacitor  30  from discharging into the vehicle battery  18 .  
         [0027]     An alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3A . A power module battery  42  is connected in parallel with the capacitor  30 . There is no isolation circuit in this arrangement. The power module battery  42  provides an additional source for charging the capacitor  30  and provides supplementary starting current for the starter motor  14 . Use of the power module battery  42  allows the size of the capacitor  30  (or capacitor bank) in the module to be reduced, since starting current is not completely dependent upon the capacitor  30 . Power module battery  42  may comprise one or more rechargeable batteries of types known in the art. For example, power module battery  42  may comprise one or more lead-acid batteries (vented and non-vented), one or more deep cycle batteries, one or more nickel-cadmium batteries (vented and non-vented), one or more nickel-metal hydride batteries, one or more nickel-iron batteries, one or more nickel-zinc batteries, one or more silver-zinc batteries, one or more silver-cadmium batteries, one or more nickel-hydrogen batteries, and/or one or more lithium ion batteries.  
         [0028]     Another alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3B . Capacitor  30  and power module battery  42  are connected as was shown in the arrangement of  FIG. 3A . Diode  34  is connected between the B(+) terminal  24  and the M(+) terminal  22  as shown. The positioning of the diode  34  in the isolation circuit isolates the capacitor  30  from the power module battery  42 .  
         [0029]     Another alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3C . Capacitor  30 , power module battery  42 , and diode  34  are connected as was shown in the arrangement of  FIG. 3B . In addition, voltage booster  41  is added to power module  20  as shown. Voltage booster  41  compensates for the voltage drop through diode  34  to boost the rate at which the capacitor  30  recharges. It will be noted that the functions of diode  34  and voltage booster  41  may be combined in a single circuit.  
         [0030]     Another alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3D . Capacitor  30  and power module battery  42  are connected as was shown in the arrangement of  FIG. 3A . Low-loss isolation circuit  43  is connected between the B(+) terminal  24  and the M(+) terminal  22  as shown. The positioning of the low-loss isolation circuit  43  in the isolation circuit isolates the capacitor  30  from the power module battery  42 , but does so in a way that may be more efficient than diode  34 . Low-loss isolation circuit  43  comprises an arrangement of active components selected to reduce the losses/voltage drops relative to using a diode. For example, loss isolation circuit  43  may comprise a pulse wave modulator or DC chopper circuit. Low-loss isolation circuit  43  may serve to limit the contribution of the power module battery  42  to the cranking/starting of the vehicle. Low-loss isolation circuit  43  could also limit the current passed to the capacitor  30  during recharging.  
         [0031]     Another alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3E . Capacitor  30 , power module battery  42 , and diode  34  are connected as was shown in the arrangement of  FIG. 3B . A charge circuit  40  is connected between power module battery  42  and diode  34 . Also shown is fuse  36 , which is optional in this arrangement. Charge circuit  40  also may or may not be required depending upon the type and size of power module battery  42  used. For example, if an appropriately sized simple lead acid battery is deployed as power module battery  42 , the charge circuit  40  may not be required. However, a charge circuit may be desirable for other types of batteries deployed as power module battery  42 . The charge circuit  40  may comprise any of a number of different means for charging a rechargeable battery used in the field of battery charging. For example, the charging circuit could be as simple as a single resistor or it could be a switcher circuit used to limit the current or control the voltage provided to the battery. The type of charge circuit  40  selected by the practitioner in a particular implementation of the present invention will depend upon the type of power module battery  42  selected by the practitioner for the module, as some batteries respond better to fixed voltage charging, some respond better to fixed current charging, etc. In each case where a charge circuit is used, the charge circuit selected to correspond to the type of battery deployed as power module battery  42 . Charge circuit  40  as shown may comprise a portion an overall master charging circuit controlling charging of both the power module battery  42  and the capacitor  30 .  
         [0032]     Another alternative arrangement for the electrical components in the module  20  is shown in  FIG. 3F . Capacitor  30  and power module battery  42  are connected as was shown in the arrangement of  FIG. 3A . An active charge/isolation circuit  45  is connected between the B(+) terminal  24  and the M(+) terminal  22  as shown. Active charge/isolation circuit  45  comprises an arrangement of active components selected to provide a charging and/or isolation function in the arrangement shown in  FIG. 3F . For example, active charge/isolation circuit  45  may comprise a pulse wave modulator or DC chopper circuit and also circuitry that provides a voltage boost function. Charge circuit  40  also is shown for power module battery  42 .  
         [0033]      FIGS. 4 and 5  provide an exemplary arrangement for electronic components within the module. As shown in  FIG. 4 , the module includes a lower base  50  and an upper cap  52 . The base  50  and upper cap  52  are both made of a nonconductive material that provides electrical insulation between the interior and exterior of the module. Such nonconductive materials are known in the art of battery manufacturing. The base  50  includes an exterior wall  60 , a floor  62 , a dividing wall  64 , and a cover portion  66 . The dividing wall  64  splits the base into two chambers. The first chamber  54  is designed and dimensioned to retain the power module battery  42 . The second chamber  56  is designed and dimensioned to retain the capacitor or capacitor bank  30 . A first post  70  is connected to the Neg(−) terminal  26 , extends through the upper cap  52 , and joins to the negative lead/terminal of the capacitor bank  30 . A second post  72  is connected to the M(+) terminal  22 , extends through the upper cap  52 , and joins to the positive lead/terminal of the capacitor bank  30 . A third post (not shown) is connected to the B(+) terminal  24 , extends into the upper cap  52 . The isolation circuit  32  is positioned in the upper cap  52  and connects the M(+) terminal  22  to the B(+) terminal  24  by extending between the second and third posts. The charge circuit  40  is positioned below the isolation circuit and provides the connection between the B(+) terminal  24  (and associated third post) and the positive lead of the power module battery  42 . As explained previously, with reference to  FIG. 3 , the negative lead of the secondary battery is joined to the negative terminal. Altogether, the module  20  provides a compact unit housing all of the electrical components required for a supplementary current starting system in a motor vehicle. The module is compact and approximately the size of a typical vehicle battery, such that the module can be implemented into new or existing vehicle engine compartments.  
         [0034]     In operation, the module is first connected to a vehicle&#39;s electrical system, as described above with reference to  FIG. 1 . The module  20  is put in use when the vehicle operator turns the key to the start position, and the ignition switch is closed. With the ignition switch closed, a connection between the starter  14  and the M(+) terminal  22  of the module is established. This allows current to flow from the capacitor  30  directly to the starter  14 , and the engine  12  is cranked. The power module battery  42  may provide additional current during starting, especially if an unusually long cranking time is required to start the engine. Furthermore, some current may be provided by the vehicle&#39;s standard SLI (starting, lighting, ignition) vehicle battery  18 , if the standard SLI vehicle battery  18  is sufficiently charged.  
         [0035]     Once the engine starts following cranking, a substantial amount of energy has been drained from the capacitor, and the capacitor is ready for recharge. However, when the engine first starts, and is running at idle speed, there is typically not enough current generated from the charging system (i.e., alternator/generator) to completely re-charge the capacitor. If the vehicle&#39;s standard vehicle battery  18  and/or the power module battery  42  of the module are sufficiently charged, they may provide some immediate current for re-charging the capacitor. Alternatively, once the engine is operated at an increased speed above idle speed, the generator will provide current for recharging the battery (or batteries) and the capacitor. Because the capacitor  30  is an energy storing device that is capable of fast charge and discharge cycles, operation of the engine for only a short amount of time at speeds above idle speed (e.g., 20 seconds) will fully re-charge the capacitor  30 .  
         [0036]     During charging of the capacitor  30 , energy flows through the fuse  36  and a diode  34  acting as the isolation circuit. During and after re-charging of the capacitor  30 , the diode  34  of the isolation circuit  32  provides one-way flow of energy from the charging system to the capacitor  30  in the module. By providing isolation from the charging system, the module&#39;s energy cannot be drained back to the vehicle battery  18  while the vehicle is idling at a stop or if the engine is not running and there is an electrical load on the vehicle (flashers, radio, lighting, etc.). The fuse  36  protects the diode  34  and also serves as a safety device to disconnect the vehicle battery  18  from the starter  14  in the event of stuck contacts on the starting motor solenoid.  
         [0037]     In an alternative embodiment shown in  FIG. 6 , the power module  20  completely replaces the vehicles standard/existing battery. In this embodiment, the module  20  includes a power module battery  42  which acts to replace the vehicle&#39;s standard battery. The size of the module  20  is sufficiently close to the size of the vehicle&#39;s standard battery that the module can simply be inserted in place of the vehicle&#39;s standard battery. For example, the module  20  may be sized to substantially correspond to the dimensions prescribed in a Battery Council International group number specification. Thus, the module  20  may be easily included in current vehicle designs and the module  20  may also be used as an easily installed aftermarket product. The embodiment of  FIG. 6  could easily be used in vehicle applications with relatively small electrical loads, such as passenger cars and light trucks. However, the embodiment of  FIG. 1  where the module (including a secondary battery) is used in association with the vehicle&#39;s standard battery may be more desirable for vehicles having larger on-board and off-board loads, such as recreational vehicles and heavy trucks.  
         [0038]     As described above, the power module according to the present invention features short re-charge times which are particularly valuable in the delivery vehicle market. Because of low internal resistance, the capacitor banks are also capable of providing cranking current at a lower voltage than the battery. In addition, the module is continuously connected to the charging system of the vehicle, which makes implementation of the module in a vehicle relatively simple with no switching. The module may also take advantage of the presence of the secondary battery during starting, thereby allowing the module to be designed with smaller banks of capacitors. The module with a secondary battery is sized such that it can be used in place of a vehicle&#39;s standard battery, or it can be used to supplement the vehicle&#39;s standard battery. Furthermore, the existence of the module provides for longer battery life, as less reliance on the battery helps avoid extremely deep battery discharge.  
         [0039]     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other versions are possible. For example, to protect the generator from the requirement of immediately operating at full load upon engine fire the until the capacitor has re-charged, the charge current to the capacitor may be limited by electronic means or by simply introducing some resistance to the isolation circuit (e.g., simply adding a resistor or choosing a diode with a ‘slow response’). As another example, if milling issues are noticed between the starter motor and flywheel due to the higher energy available from the use of capacitors as an energy storage device, resistance may be added to the lead/cable connecting the starter motor to the module (e.g., by making the leads longer, thus increasing the resistance in the connection and reducing the initial current the starting motor solenoid receives). Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.