Abstract:
A cold starting system and power management software consisting of an air heater system, a fuel heater system, a controller with microprocessor and related software, a series of devices comprising of switches, indicators, solenoids and sensors, is used as an aid to assist start up of air cooled combustion engines in extreme temperature environments. Both the air and fuel heater systems include electrically powered heating elements. The power management software controls the sequential operation of individual system components.

Description:
[0001]    (Divisional of US patent application Ser. No. 09/476,968, filed on Dec. 30, 1999, claiming priority from CA patent application 2,293,134) This invention relates to a cold starting aid system for internal combustion engines. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Air-cooled internal combustion engines are employed in a variety of applications in everyday life, from mopeds to family transport, large trucks, and industrial power plants. Today&#39;s engines are designed to operate reliably within a limited temperature range, typically between −20° C. to 40° C. When faced with extreme operating conditions, such as low temperatures, consistent engine start up and operation cannot be relied upon without assistance.  
           [0003]    In order to initiate the combustion of an air/fuel mixture in a combustion chamber of an engine, the internal energy of the mixture must be raised to a critical level. For gasoline engines, this is typically accomplished through a compression of the air/fuel mixture and a subsequent ignition supplied by a spark plug. If the engine start up is not achieved immediately, then power, supplied by a battery is used to crank the engine over an extended period of time until the engine starts. In extreme cold conditions, a block heater can sometimes be relied upon, to warm up the engine block and, thereby, raise the internal energy of the fuel and air closest to the combustion chamber, in combination with the compression cycle and the ignition spark. The disadvantages of this start up aid is that it expends energy not used during start up, it requires time to warm up the engine block before starting can be tried, and an external energy source must be used to power the block heater. It is not uncommon for the battery to run out of charge at extreme cold temperatures before achieving start up.  
           [0004]    In operation with diesel engines in extreme temperature conditions, raising the internal energy of the air/fuel mixture is accomplished by compression of the air/fuel mixture only, or by compression and the use of an electric glow plug. These starting systems are suitable only for smaller size engines with high compression ratio and high RPM (automobile diesel engines). Larger engines, like the ones of transport trucks, require different starting aids. Some are using the same block heaters as for the gasoline engines. The block heaters are not usually relied upon because of inaccessibility en-route (no external power source to connect the heater). Therefore, at low temperatures, it is not uncommon to leave the engine running rather than risk restart. Also, the use of a block heater is practical where the engine is water-cooled, but in some applications air cooled engines are preferred. The start up of diesel engines can also experience other disadvantages, namely running down of the battery, extended start up times, and excessive use of power resources.  
           [0005]    One startup aid for diesel engines is to heat the intake air with fuel-fired (combusting) glow plugs. This starting aid is reliable only if the engine draws excess amounts of air through its intake manifold to supply oxygen to both the fuel fired glow plugs and a fuel charge in the combustion chamber. Otherwise, the fuel-fired glow plug can consume all the oxygen in the air and “starve” the engine.  
           [0006]    A particular problem arises where an internal combustion engine is used to drive stationery equipment, e.g. a generator or pump. Such devices are used intermittently and may remain idle or in storage for extended periods. The devices typically are transported to a remote location and the engine must be able to start quickly and reliably without significant preparation.  
           [0007]    It is therefore an objective of the present invention to provide a cold starting aid system and a starting method that will obviate or mitigate the above disadvantages.  
         SUMMARY OF THE INVENTION  
         [0008]    In general terms, the present invention relates to a cold start system for internal combustion engines and its method of use. In one aspect of the invention, there is provided a cold start system for an engine having at least one fuel injector and an air intake manifold to supply fuel and air respectively, into a combustion chamber. The cold start system includes at least one heating element to be disposed in the air intake manifold to heat a body of air and at least one heating element to be disposed around the fuel injector to heat the fuel contained therein.  
           [0009]    Preferably, a controller, including a series of switches, is used to regulate a supply of power from a battery to the starter, and the plurality of heating elements. The controller is connected to a microprocessor with associated power management software. The software directs the controller by way of a feed back loop connected to an ambient temperature sensor, to select an appropriate heating and cranking cycle. Additional sensors can be incorporated into the controller and include a RPM sensor which detects if the engine has started, an oil pressure sensor which monitors the pressure of the oil, a water sensor which detects if there is water present in the fuel, and a range RPM sensor which detects if the speed of the engine is outside of the normal operating range.  
           [0010]    In a preferred embodiment, a fuel pre-heat system consists of a heater body mounted around the fuel injector. The body houses the fuel injector and a thermally conductive gasket may be positioned between the body and the fuel injector, to enhance heat transfer there between. A plurality of heating elements are inserted into a series of holes located around an exterior of the body, which minimizes the distance between the fuel pre-heat system and the combustion chamber.  
           [0011]    An air pre-heat system of a preferred embodiment includes a spacer located in the air intake manifold and a plurality of heating elements. A series of ports are preferably located in a peripheral wall of the spacer, into which the heater elements are inserted. A thermal insulator may be positioned between the spacer and the air intake manifold. A plurality of insulating fasteners are used to mount the spacer to the air intake manifold and minimize heat transfer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:  
         [0013]    [0013]FIG. 1 is a schematic representation of an internal combustion engine including a cold starting aid system.  
         [0014]    [0014]FIG. 2 is a plan view of a fuel heater used in the system of FIG. 1.  
         [0015]    [0015]FIG. 3 is a section on the line A-A of FIG. 2.  
         [0016]    [0016]FIG. 4 is a side view of an air heater.  
         [0017]    [0017]FIG. 5 is a section on the line B-B of FIG. 4.  
         [0018]    [0018]FIG. 6 shows details of start sequences.  
         [0019]    [0019]FIG. 7 shows details of start sequences.  
         [0020]    [0020]FIG. 8 shows details of start sequences.  
         [0021]    [0021]FIG. 9 shows details of start sequences. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    Referring to FIG. 1, a typical air-cooled internal combustion engine  10  includes a crank case  11 , a crank shaft  12  connected to a piston  14  which is housed in a cylinder  16 , and a to combustion chamber  18  disposed between the piston  14  and cylinder  16 . An air intake manifold  24  and an exhaust manifold  26  are connected to the combustion chamber  18 . A starter  22  is connected to the crankshaft  12 . An electrical fuel pump  30  is connected by fuel lines  13  to a fuel injector  28 , which supplies the fuel  34  to the combustion chamber  18 . The fuel pump  30  is controlled by a “Fuel ON” solenoid  31 , and a “Fuel OFF” solenoid  32 , to regulate the supply of electrical power from a battery  56  to the pump  30 . The voltage supplied to the system by the battery  56  can be 12 volt DC or 24 volt DC. Incorporated in the engine  10  is a cold starting aid system  8  consisting of a fuel heater  35  distributed around the fuel injector  28  to heat the fuel  34 , and an air heater  43  positioned on the air intake manifold  24  to heat the air  33 .  
         [0023]    The fuel heater  35 , shown in FIGS. 2 and 3, includes a heater body  38 , which is mounted onto the cylinder  16  of FIG. 1, and a recess  42  in the body  38  to encompass the body of the fuel injector  28 . A thermally conductive gasket  40  is positioned between the heater body  38  and the injector  28  to enhance the transference of heat therebetween. A plurality of heating elements  37 , which in the preferred embodiment are electric Firerod cartridges, are inserted into a plurality of corresponding holes  41  located around an exterior of the heater body  38 . These heating elements  37  are powered by the battery  56  of FIG. 1.  
         [0024]    The air heater  43  of the preferred embodiment, shown in FIGS. 4 and 5, includes a spacer  48  and a plurality of heating elements  36 . A series of ports  44  are located in a peripheral wall  46  of the spacer  48  in a staggered orientation, into which the heater elements  36  are inserted. In the preferred embodiment, the air heating elements are electric Glow plugs that are powered by a 12 volt DC battery  56 . For systems that use 24 volt DC power, the spacer  48  is divided into a first portion  47  and a second portion  49 . An electrical insulator  51  is sandwiched between the portions  47 ,  49 , of the spacer  48 , in order to separate the electrical grounds of the two portions  47 ,  49 . A thermal insulator  50  is positioned between the spacer  48  and the air intake manifold  24 , to help inhibit thermal transfer to the rest of the engine  10 , which may act as a thermal heat sink. The same thermal insulator  50  acts as an electrical insulator, which electrically isolates the spacer from the air manifold  24 . A wraparound housing  80 , made of a thermally conductive material, such as aluminum, is installed on both sides of the spacer  48  in order to protect the heating elements  36  from the inclusion of foreign matter. A plurality of insulating fasteners  45  are used to mount the spacer  48 , thermal insulator  50 , and wraparound housing  80  to the air manifold  24 .  
         [0025]    A controller  52 , including a series of switches  54 , is used to regulate the supply of power from the battery  56  to the starter  22 , the “Fuel ON” solenoid  31 , the “Fuel OFF” solenoid  32 , and the heating elements  36 . The controller  52  is connected to a microprocessor with real time clock  62  and is controlled by the associated power management software  60 . The software  60  directs the controller  52  by way of a feedback loop  57  connected to a temperature sensor  58  to select an appropriate heating and cranking cycle. The heating/cranking cycle depends of the ambient temperature read by the temperature sensor  58 . In the preferred embodiment, the temperature of the oil  9  in the crankcase  11  is monitored for an indication of ambient temperature. Additional sensors can be included to feed various signals into the controller, in order to monitor the engine operation. Examples of additional sensors include a proximity sensor  64  which detects if the engine  10  has started, an oil pressure sensor  66  which monitors the pressure of the oil  9 , a water in fuel sensor  68  which detects if there is water present in the fuel  34 , and a range RPM sensor  70  which detects if the speed of the engine  10  is outside of the normal operating range. All the run or fault states monitored by the various sensors are indicated on the controller  54  by a series of indicators  69 .  
         [0026]    The operation of the cold starting aid system  8  in connection with the internal combustion engine  10  is directed by a series of different start up sequences  71 ,  72 ,  73 ,  74 ,  75 ,  76 ,  77  and  78 , given in FIGS. 6 through 9. Each of the start up sequences  71 - 78  provides a different sequence of the operation of the starter  22 , fuel pump  30 , solenoids  31 ,  32 , and heating elements  36 ,  37 . The sequencing logic of the power management software  60  directs the order in which the components  22 ,  31 ,  32 ,  36 ,  37  are enabled or disabled, in order to minimize the amount of power required for start up of the engine  10 . In certain instances the air  33  and the fuel  34 , either simultaneously or separately, are heated for a certain delta time unit before being delivered into the combustion chamber  18 . In other instances, the air  33  and fuel  34  are delivered into the combustion chamber  18  without the application of heat.  
         [0027]    The power management software  60  selects which of the particular startup sequences  71 - 78  is followed, preferably based on the ambient temperature measured by the temperature sensor  58  in the oil  9 . By way of example only, an outline of the start up sequence  77  for the temperature range −32° C. to −41° C. shown in FIG. 9 is now described.  
         [0028]    For the first six seconds the starter  22  is de-energized and the fuel pump  30  and the air and fuel heaters  35 ,  43  are energized, thereby heating the air  33  situated near the spacer  48  and heating the fuel  34  deposited into the fuel injector  28  by the pump  30 , before the crankshaft  12  is rotated. After the sixth second until the end of the fifteenth second the fuel pump  30  is de-energized, the starter  22  remains de-energized, and the fuel and air heating systems  35 ,  43  remain energized, thereby further heating of the air  33  near the spacer  48  and heating of the fuel  34  retained in the injector  28 . After the fifteenth second until the end of the eighteenth second the fuel pump  30  is energized, the fuel and air heating systems  35 ,  43  are de-energized, and the starter  22  is energized, thereby allowing the pre-heated air  33  and the pre-heated fuel  34  to be drawn into the combustion chamber  18  as the crankshaft  12  is rotated. Further amounts of fuel  34  and air  33  supplied to the combustion chamber IS are not pre-heated. After the eighteenth second until the end of the thirtieth second all the components  30 ,  35 ,  43  and  22  are energized, whereby the fuel  34  and the air  33  are heated as they flow into the combustion chamber  18 , during rotation of the crankshaft  12 . If the engine  10  starts, the proximity sensor  64  detects the increase in speed and directs the controller  52  to stop the heating and cranking cycle.  
         [0029]    If after the thirtieth second the engine  10  has not started, the fuel pump  30  and the starter  22  are de-energized while the fuel and air heating systems  35 ,  43  remain energized until the thirty ninth second. These systems  35 ,  43  continue to pre-heat the air  33  situated in the vicinity of the spacer  48  and the fuel  34  retained in the injector  28 , before the crankshaft  12  is further rotated. After the end of the thirty ninth second until the end of the forty fifth second the fuel pump  30  and starter  22  are energized and the fuel and air heating systems  35 ,  43  are de-energized, thereby supplying the pre-heated air  33  and the pre-heated fuel  34  to the combustion chamber  18 , during crankshaft  12  rotation. Further amounts of fuel  34  and air  33  supplied to the combustion chamber  18  are not pre-heated. After the forty fifth second until the end of the sixtieth second all the components  30 ,  35 ,  43 , and  22  are energized, whereby the air  33  and fuel  34  supplied to the combustion chamber  18  are pre-heated as the crankshaft  12  is rotated.  
         [0030]    The start-up sequence  77  is completed after the end of the sixtieth second, where by this point if the engine  10  has not started the sequence  77  can be repeated up to four times. The proximity sensor  64  will interrupt the start up sequence  77 , once the engine  10  has started, at any time during the ignition process. The other sensors  66 ,  68 , and  70  can also interrupt the ignition process.  
         [0031]    Different ambient temperatures will initiate different sequences as indicated by the sequences  71 - 76  and  78  where a “1” indicates an energized state and “0” indicates a de-energized state. It should be noted that sequence repetition and interruption is experienced by the other startup sequences  71 - 76  and  78  as well.  
         [0032]    The cold starting aid system  8  can be used with 12 volt DC and 24 volt DC batteries  56 . The fuel heating elements  37  in the preferred embodiment are electric Firerod cartridge plugs and are preferably pressed into the holes  41  of the heater body  38 . The heater body  38  is made of a conductive material, such as aluminum. The casket  40  between the body  38  and injector  28  is made of a silicone based compound containing zinc oxide, such as Wakefield Engineering Thermal Joint Compound, which is typically malleable in order to fill in the space between the body  38  and injector  28 . Placement of the fuel heater  35  around the fuel injector  28  minimizes the distance between the heater  35  and the combustion chamber  18 , shown in FIG. 1. This results in heating of the fuel  34  closest to the combustion chamber  18  which inhibits the potential risk of vaporizing the fuel  34  in the fuel lines  13 , whereby vapor lock can occur. The air heating elements  36  in the preferred embodiment, are electric Glow plugs and are preferably threaded into the ports  44  of the spacer  48 . The use of non-combusting heaters  36  in the air intake  24  ensures that the air  33  is heated without depleting the oxygen in the air  33  inside the intake manifold  24 . The thermal insulator  50 , the electrical insulator  51 , and the fastener  45  are made of an insulating material such as Teflon.  
         [0033]    During testing, the heat output of the four Fireroad cartridges used as fuel heating elements  37  to heat the fuel  34  in the vicinity of the fuel injector  28 , reached a maximum of 200 watts in less than 4 seconds. The four Glow plugs used as air heating elements  36 , for the air heater  43 , obtained a maximum heat output of 480 watts in less than 4 seconds. The amount of heat generated to heat the fuel  34  and air was adequate and enough to produce a reliable engine start in less than one minute, and a sustained operation for all ambient temperature ranges investigated.  
         [0034]    All of the start up sequences  71 - 78  are typically of one minute in duration. These ignition processes can be repeated up to four times and are interruptible if the proximity sensor  64  detects that the engine  10  has started. The oil temperature ranges tested were 140° C. to 4° C. for sequence  71 , 4° C. to 4° C. for sequence  72 , −4° C. to −12° C. for sequence  73 , −12° C. to −18° C. for sequence  74 , −18° C. to −25° C. for sequence  75 , −25° C. to −32° C. for sequence  76 , −32° C. to 41° C. for sequence  77 , and −41° C. to −55° C. for sequence  78 . The temperature of other mediums, such as the ambient air, can also be used as input to the power management software  60 .  
         [0035]    Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.