Abstract:
An engine starting assist system. A battery is selectably coupled to an ultracapacitor with a contactor. In addition, a controller is configured to perform at least one of: monitor the condition of the battery, monitor the condition of the ultracapacitor, control the flow of energy between the battery and the ultracapacitor by selective actuation of the contactor, receive a start input control. The controller issues a start output control to a starter solenoid of the engine, such that energy stored in the ultracapacitor may be used to at least one of charge the battery and provide cranking current to a starter of the engine in conjunction with the battery.

Description:
This application claims priority to U.S. provisional patent application No. 60/969,323, filed Aug. 31, 2007, the contents of which are hereby incorporated by reference. 
    
    
     FIELD 
     The present invention relates generally to vehicle electrical systems, in particular to a system to assist with vehicle engine starting and to start a vehicle having a discharged engine cranking battery. 
     BACKGROUND 
     It is unfortunately a relatively common experience among many operators of motor vehicles that a well-maintained or even relatively new internal combustion engine cannot be started when the battery that supplies the power to the starter is discharged below a minimum power level needed to crank the engine. In many cases an external power source, such as a second battery, must be coupled to the discharged battery with jumper cables to provide auxiliary power to start the engine. However, such external power sources and/or cables may not be readily available. In addition, connecting jumper cables to a battery can be dangerous because the battery emits combustible gases, and a spark resulting from such a connection may ignite the gases. Furthermore, improper connection of the jumper cables between the auxiliary battery and the discharged battery can cause damage to the vehicle&#39;s electrical system. 
     Another common problem associated with motor vehicles is that the cranking battery used to start the internal combustion engine has reduced amp-hour capacity at low ambient temperatures due to the temperature sensitivity of the chemical reactions inherent in such batteries. This drawback, coupled with the typically greater cranking current required to overcome the increased internal friction of a cold engine, can result in a failure to start the engine, particularly if the battery has not been fully charged or suffers from reduced capacity due to battery aging. 
     Yet another concern is the high cranking current demanded of a battery during the starting cycle of an internal combustion engine. This high current demand can quickly and deeply discharge the battery, which adversely affects the capacity and life of the battery. There is a need for a way to utilize on-board supplementary power sources to provide auxiliary power to start the vehicle&#39;s engine and to charge the cranking battery when it is discharged. 
     SUMMARY 
     A starting system for an internal combustion engine according to an embodiment of the present invention includes a battery which supplies electrical energy to a starter motor through a starter control to start the engine. An alternator driven by the engine charges the battery. The starter control utilizes a controller and an ultracapacitor to assist the battery in providing energy to the starter to crank the engine for starting. The starter control may also transfer to the battery energy stored by the ultracapacitor, thereby charging the battery. 
     An object of the present invention is an engine starting assist system. A battery is selectably coupled to an ultracapacitor with a contactor. In addition, a controller is configured to perform at least one of: monitor the condition of the battery; monitor the condition of the ultracapacitor; control the flow of energy between the battery and the ultracapacitor by selective actuation of the contactor; and receive a start input control. The controller issues a start output control to a starter solenoid of the engine, such that energy stored in the ultracapacitor may be used to at least one of charge the battery and provide cranking current to a starter of the engine in conjunction with the battery. 
     Another object of the present invention is a method for controlling the starting of an engine. A battery is selectably connected to a starter of the engine. An ultracapacitor is provided, and at least one of the battery and the ultracapacitor are charged. The battery and the ultracapacitor are selectably coupled together such that energy stored in the ultracapacitor may be used to at least one of charge the battery and provide cranking current to a starter of the engine in conjunction with the battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following specification with reference to the accompanying drawings, in which: 
         FIG. 1  is a block diagram of a vehicle starting assist system according to an embodiment of the present invention; 
         FIG. 2  is a block diagram of a vehicle starting assist system according to an alternate embodiment of the present invention; 
         FIG. 3  is a block diagram of a vehicle starting assist system according to another alternate embodiment of the present invention; and 
         FIG. 4  is a block diagram of a vehicle starting assist system according to yet another alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the discussion that follows, like reference numerals are used to refer to like elements in the various figures. 
     With reference to  FIG. 1 , according to an embodiment of the present invention a starting system  10  for an internal combustion engine  12  comprises a capacitor  14  which supplies electrical energy to a starter motor  16  through a starter control  18  to start the engine. An alternator  20  that is mechanically driven by engine  12  generates electrical energy to charge a battery  21 . 
     Starter control  18  includes a controller  22  that controls actuation of a contactor  24  that is coupled between a positive terminal of battery  21  and a positive terminal of capacitor  14 . Controller  22  also selectably controls actuation of a pre-charge switch  28  that is connected in parallel with contactor  22  and a start switch  30  that is coupled between a START_IN input  32  and a START_OUT output  34  of starter control  18 . A manual switch  36  is connected between a negative terminal of capacitor  14  and a negative terminal of battery  21 . 
     Controller  22  may be implemented in any conventional form including, without limitation, computers, microcontrollers, central processing units (CPU), programmable controllers and logic devices, microprocessors, and ladder logic devices. Controller  22  may include one or more sets of predetermined algorithms and/or instructions (hereafter “computer program”) to define the various operational aspects of the controller. The computer program may be stored in a memory portion of controller  22 . 
     In one embodiment of the present invention capacitor  14  is a conventional “ultracapacitor.” Ultracapacitors provide a large amount of capacitance in a very small form factor, thereby providing for storage of significant amounts of energy in a relatively small package. Ultracapacitors are sometimes referred to as “supercapacitors,” “electrochemical capacitors” and “double layer capacitors.” Ultracapacitors are notable for their ability to store more energy per unit weight and volume than conventional capacitors. They are also able to deliver the stored energy at higher rates than is possible with other electrochemical devices, such as batteries. 
     Although switches  28 ,  30  are shown schematically in  FIG. 1  as single pole single throw (SPST) switches, it will be appreciated that these switches may be implemented using electronic components including, without limitation, transistors. Furthermore, the on-off duty cycle of the switches  28 ,  30  may be controlled in a predetermined manner by controller  22 . For example, pre-charge switch  28  may be duty cycle controlled using pulse width modulation to control or limit the amount of current flowing therethrough, thereby acting as a charge control for energy flowing from battery  21  to capacitor  14  and vice versa. 
     In some embodiments of the present invention either or both of the SPST on-off type switches  28 ,  30  of  FIG. 1  may be implemented in the form of selectably activated unidirectional or bidirectional DC-DC converters. For example, with reference to  FIG. 2 , in a starting assist system  100  switch  28  may be configured as a step-up DC-DC converter  37  to selectably, under the control of controller  22 , convert a relatively low battery  21  voltage to a higher DC voltage for charging capacitor  14 . In this way DC-DC converter  37  functions as both on-off switch  28  and as a voltage converter. Likewise, on-off switch  30  of  FIG. 1  may be similarly implemented as a DC-DC converter  39  selectably controlled by controller  22 , as shown in  FIG. 2 . 
     Electrical power for operating controller  22 , contactor  24  and switches  28 ,  30  may be supplied by one or more of battery  21 , capacitor  14 , and control signals provided to START_IN input  32  and POWERON input  38 . These inputs and control signals are detailed further, below. 
     With reference again to  FIG. 1 , during one operational mode of system  10 , starter control  18  is activated by supplying an activation control signal to POWERON input  38  of the starter control, the activation control signal being received by controller  22 . In one embodiment of the present invention the activation control signal is provided by an IGNITION output  40  of a conventional multiplexed vehicle control system  42 , the activation control signal being either a selectively applied voltage (logic high active state) or selectively applied ground (logic low active state) input. Multiplexed vehicle control systems  42  utilize communications buses to reduce the number of wires required to link vehicle accessories with the appropriate accessory switch and to link displays and control systems with the appropriate sensors and transducers. In general terms, each accessory switch and each sensor are coupled via appropriate transmitters to a data bus line. Similarly, each accessory and each display or other receivers of sensor information such as, for example, control processors, are coupled via appropriate receivers to the same bus line. 
     Alternatively the POWERON activation control signal may be provided by a dead battery switch  44  as shown in  FIGS. 3 and 4 . Dead battery switch  44  may be connected to a positive terminal  48  of battery  21  in a starting system  200 , as shown in  FIG. 3 . In this embodiment of the present invention POWERON input  38  is configured as a selectively applied voltage (logic high active state) connection. Dead battery switch  44  may alternatively be connected to a negative terminal  50  of battery  21  in a starting system  300 , as shown in  FIG. 4 . In this embodiment of the present invention POWERON input  38  is configured as a selectively applied ground (logic low active state) connection. 
     With the POWERON input  38  in an active state, upon receiving an appropriate (i.e., active high or active low state) start control signal at START_IN input  32 , controller  22  closes start switch  30  to supply a corresponding output start control signal at START_OUT output terminal  34 , the output start command signal being communicated to a solenoid  46  configured to selectably couple energy from battery  21  to starter  16 . Upon receiving the output start command signal solenoid  46  couples starter  16  to battery  21  to engage the starter, thereby starting engine  12 . In this operational mode controller  22  checks the voltages of battery  21  and capacitor  14  using connection lines (not shown) coupled thereto and determines that battery  21  is sufficiently charged to start engine  12 . Controller  22  may optionally actuate contactor  24  or switch  28  to charge capacitor  14 , if desired. 
     In a second operational mode of system  10 , if additional energy is needed to operate starter  16 , an activation signal is provided to POWERON input terminal  38  by IGNITION output  40 , thereby activating controller  22 . Controller  22  checks the voltages of battery  21  and capacitor  14  using connection lines (not shown) coupled thereto. If controller  22 , using predetermined criteria, determines that capacitor  14  requires charging, the controller actuates pre-charge switch  28  causing energy to flow from battery  21  to the capacitor therethrough. When controller  22  determines, using predetermined criteria, that capacitor  14  is sufficiently charged, a START_IN control signal provided to input  32  of starter control  18  and received by the controller causes the controller to actuate start switch  30 , thereby engaging starter  16  in the manner previously described. Controller  22  also actuates contactor  24 , thereby coupling capacitor  14  to battery  21  such that engine-cranking current is supplied to starter  16  by both the battery and the capacitor. A significant portion of the cranking current will be supplied by capacitor  14 , as the capacitor has a relatively low internal impedance. 
     When engine  12  starts the engine will mechanically drive alternator  20 , the electrical output of which charges both battery  21  and capacitor  14 . Controller  22  monitors the charging process and de-actuates contactor  24  and/or switch  28  when capacitor  14  is charged. This prevents discharge of capacitor  14  when engine  12  is off but accessories (not shown) are connected to battery  21  and consuming energy therefrom. 
     In a third operational mode of system  10 , when engine  12  is off and accessories are left coupled to battery  21 , the battery may become discharged. In some cases the discharged battery  21  voltage may drop to a level that is too low to operate multiplexed vehicle control system  42 , preventing the generation of an IGNITION output  40  control signal. In such cases POWERON terminal  38  of starter control  18  may alternately be connected to dead battery switch  44  to activate controller  22  in the manner previously described. In particular, it will be appreciated that, if a logic low active state connection is utilized for dead battery switch  44 , a control (i.e. ground) signal may be provided to POWERON input  38  even if battery  21  is completely discharged. When controller  22  is activated the controller actuates contactor  24  causing charging current to flow from a charged capacitor  14  to battery  21 . When the battery  21  is recharged to a predetermined minimum voltage level, multiplexed vehicle control system  42  will resume normal operation, thereby providing an IGNITION output  40  control signal and allowing an engine  12  starting cycle in the manner previously described. 
     Manual switch  36  may be used by an operator of system  10 . When switch  36  is closed system  10  operates in the manner described above. When switch  36  is open capacitor  14  is disconnected from battery  21 . Thus, manual switch  36  may be used as a safety device to disable system  10  for servicing or maintenance. 
     As can be appreciated from the foregoing discussion, engine starting system  10  supports engine  12  start assist during normal battery charge conditions, and provides an alternate energy source for starting the engine in the event of a dead battery. In the process of carrying out these functions system  10  pre-charges capacitor  14  via switch  28  before closing contactor  24  when capacitor voltage is low. This prevents a large inrush current from the battery to the capacitor. 
     Furthermore, a START_IN control signal provided to input  32  is ultimately originated by an operator desiring to start engine  12 . System  10  evaluates the charge condition of battery  21  and capacitor  14  and generates a START_OUT output  34  control signal only after optimum energy control of the battery and capacitor, for their condition, has been realized. Consequently, a greater amount of energy is available to crank engine  12 . System  10  also provides a way to charge a discharged battery  21  using energy stored by capacitor  14 . System  10  thus reduces battery wear due to deep discharging and also provides a higher probability of a successful engine  12  start. 
     While this invention has been shown and described with respect to a detailed embodiment thereof, it will be understood by those skilled in the art that changes in form and detail thereof may be made without departing from the scope of the claims of the invention.