Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/475,630 filed Apr. 14, 2011, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention pertaining to diesel, gasoline, alternative-fuel internal combustion engines, is comprised of a closed loop electronic control system, to deliver a more precise amount of oil through a solenoid valve and cooling nozzle to a piston underside, and in particular, shall improve or even optimize the piston dome temperature for the reduction of soot production and particulate matter both in the oil and out the exhaust, allowing for increased engine efficiency at all operating conditions. 
     2. Description of the Related Art 
     A typical internal combustion engine includes an engine block with a reciprocating piston within a cylinder bore. The piston assembly travels a fixed distance in a cylinder bore and is connected to a connecting rod which in turn is attached to a rotating crankshaft. The piston is generally comprised of both a dome and a skirt (some cases, not all) and will require oil cooling to the underside of the piston dome for cooling and lubrication purposes. Typical piston cooling on a heavy duty diesel engine is generally accomplished by delivering pressurized oil from the crankcase oil system in the form of a spray or stream through a piston oil nozzle assembly, which is connected to an oil passage generally located inside the lower crankcase area. Moreover, the piston oil nozzle assembly is generally mounted directly in the lower internal crankcase area, adjacent each piston cylinder location. 
     Present technology for cooling the piston throughout the entire engine operating range, is to supply crankcase oil for cooling through the piston oil nozzle assembly explicitly to satisfy the worst case engine operating condition. Unnecessary high pumping power is required to circulate the engine oil used for cooling. The oil flow is constant for any given engine rpm and not load dependent. Moreover, if the engine is not operated at 100% load condition, resultant excessive cooling to the piston dome underside will result in overcooling the piston dome which contributes to elevated soot levels in the crankcase oil and reduced engine efficiency. To help address this issue, alternative piston cooling management systems have been developed. 
     For example U.S. Pat. No. 2,800,119 to Schmidl discloses an arrangement for cooling the piston of an internal combustion engine, more particularly, to control the share of lubricating oil branched off to the piston and piston head, in dependence upon engine speed. The improvement comprises a spray nozzle in said piston cooling branch circuit having an opening of a size to permit a flow resistance to the passage of oil less than the flow resistance in the lubricating branch circuit at engine idling speeds. Furthermore, a check valve exits connecting this said nozzle with a means for opening said valve under the pressure of the main oiling circuit during normal engine running speeds, but closing this said valve during low running or engine idling speeds. 
     While the Schmidl reference discloses a mechanism for cooling the piston throughout a range of engine operating conditions, Schmidl&#39;s enhanced spray nozzle introduces a non-return valve and compression spring assembly that will be prone to hysteresis and sticking effects. Furthermore, variations in the oil pumping circuit cannot be compensated by the open loop design of the enhanced spray nozzle, providing a non-optimized solution as thousands of hours of wear are imposed on the cooling system components. In addition, the Schmidl design is regulated by an oil pressure relief valve located in the piston oil nozzle assembly, allowing oil to the piston nozzle until the engine crankcase oil pressure exceeds the predetermined nozzle relief valve setting. At this threshold point, the piston oil spray nozzle starts flowing crankcase oil through the nozzle orifice assembly. The actual oil to the piston cooling nozzle now becomes crudely controlled by the engine rpm, determining the crankcase oil pressure. This simplistic control strategy is typically found in today&#39;s modern engines and has a minimal at best opportunity to regulate the desired oil flow to the piston for cooling. 
     U.S. Pat. No. 5,819,692 issued to Schafer, discloses a control mechanism for spraying lubrication oil to the piston, whereby the temperature of the piston is controlled within a preferable range to prevent overheating under high load conditions, or overcooling at low load conditions. A direct-acting thermostatic valve is positioned into a machined passage in the engine for diverting lubricant from the main oil gallery passage into individual branch passages leading to each spray nozzle. 
     While the U.S. Pat. No. 5,819,692 reference discloses a method to provide cooling of the piston for a range of engine conditions, the control mechanism relies on a tubular valve element that is reciprocated back and forth in the main oil passage by a thermostatic power element located in the main passage. This valve and thermostatic power element would be difficult to control due to potential sticking and hysteresis effects and would result in a sluggish response rate for the piston cooling methodology. Over the wide spectrum of rpm and load conditions imposed on the piston, mandatory precise cooling needs delivered to the pistons at the required time would be absent. 
     It is desirable to introduce an electronically controlled solenoid valve actuated by an engine power control module, to regulate oil flow for the purpose of piston cooling. To address this need, U.S. Pat. No. 6,955,142 B2 to Patel discloses the use of an electronic solenoid valve within an oil supply manifold to activate and deactivate an oil squirter system. For low engine rpm, the said solenoid valve would close to restrict oil flow and deactivate the oil squirter. As engine rpm increases, the solenoid valve would open and allow the oil to spray on the pistons and cylinders for lubrication and cooling purposes. 
     Although the electronically controlled solenoid valve in the Patel patent provides the mechanism for delivering oil for piston cooling, there exists no provision for precisely delivering oil spray based on a plurality of engine load conditions for the purpose of reducing soot production and improving engine efficiency. 
     Hence, it will be appreciated that there is a continuing need for a robust control methodology to manage the temperature of a piston dome based on rpm and load, by more precisely regulating the flow of crankcase oil. 
     SUMMARY OF THE INVENTION 
     The aforementioned needs are satisfied by the piston dome cooling device of the present invention which, in one aspect, is comprised of a pulse-width-modulated (pwm) solenoid valve or other electrically controlled solenoid valve, wherein lubrication oil from the oil sump is pumped by the oil pump through this control valve and routed to a plurality of oil spray nozzles in a parallel circuit configuration. In one implementation, one spray nozzle is utilized per cylinder and is preferably attached at the lower internal crankcase area, adjacent the bottom of each piston cylinder bore opening. Improved optimal piston cooling is achieved by routing oil through the pwm solenoid valve based on the pulse width of the feed forward command, dictated by the on-board electronic control module (ecm). It will be appreciated that this electronic closed loop methodology for piston cooling is based proportionally to the imposed thermal loading on the piston dome, rather than piston cooling delivered based on a worst case engine operating condition scenario. 
     The amount of crankcase oil delivered to the piston spray nozzle shall be a function of engine feedback parameters, rpm, torque, fuel consumption (calculated), air temperature, oil temperature, water temperature, turbo boost pressure and all necessary parameters required for optimal engine feedback control. The desired set point signal from the ecm to the pwm valve or other controllable valve shall be dictated based on these feedback parameters and a “table lookup” performed for obtaining the desired duration of the pulse width. Specifically, in one implementation, the longer the pulse width duration, the longer oil will spray to the piston. It is advantageous to tailor the pulse width duration (commonly referred to as duty cycle) based on the engine operating conditions, i.e., light load conditions shall dictate a short duration pulse width, whereas a heavy load condition (vehicle pulling a heavy load up an elevated grade) will translate into a high duration pulse width from the ecm. The pwm valve is an electronically controlled solenoid valve and is powered from the vehicle&#39;s 12 vdc power source (higher d.c. voltage sources may be required based on application), whereas the ecm is electronically interfaced to this pwm valve. The location of the pwm valve is preferably located close to the spray nozzle so as not to encourage pressure drops and/or sluggish system response in the cooling circuit. In the present embodiment, the cooling oil output port of the pwm solenoid valve is attached in a parallel fashion to a “common rail” cooling circuit to the total number of cooling nozzles, i.e., the total number of pistons in the engine block configuration (not limited to a specific number of cylinders). 
     In another embodiment, it will be appreciated that a plurality of pwm valves or similar controlled valves may be employed and each valve shall be devoted to the control of cooling on a per piston basis. In particular, the ecm shall individually manage the cooling needs of each said piston by incorporating distinct table look entries per cylinder, providing for the ultimate optimization of piston dome cooling. These additional controlled valves will provide for adequate flow characteristics to cover the oil cooling requirements of the pistons and specifically the wide-open-throttle (wot) condition. WOT is the 100% load condition and generally the worst case engine operating case scenario. It will be noted that other embodiments of the present invention may be employed; whereas a single pwm valve may be shared with multiple cylinders to provide adequate cooling for all cylinders in the engine block. 
     Another aspect of the invention comprises a system for cooling a piston of an internal combustion engine having at least one cylinder that receives the piston wherein the cylinder defines a combustion region and a cooling region, wherein the internal combustion engine includes an oil supply system that supplies oil to the cooling region of the cylinder, the system comprising one or more sensors that sense performance parameters of the internal combustion engine, an oil gating system that is controllable so that the amount of oil provided to the cooling region is adjustable, and a controller that receives signals from the one or more sensors and provides control signals to the oil gating system wherein the controller determines the amount of oil to provide to the cooling region based upon the one or more sensors so that the oil provided to the cooling region of the cylinder is reduced to inhibit excess soot production. 
     Another aspect of the invention comprises a method of controlling the production of soot by an internal combustion engine, the method comprising monitoring performance parameters of the internal combustion engine, determining the amount of oil to be delivered to a cooling region of at least one cylinder of the internal combustion engine based upon the monitored performance parameters so that the amount of soot produced by the internal combustion engine is reduced and controlling an oil gating system to control the amount of oil being delivered to the cooling region of the at least one cylinder based upon the determined amount. 
     Another aspect of the invention comprises an internal combustion engine system comprising at least one cylinder that receives at least one piston wherein the cylinder defines a combustion region and a cooling region, an oil supply system that supplies oil to the cooling region of the at least one cylinder, the system comprising, one or more sensors that sense performance parameters of the internal combustion engine, an oil gating system that is controllable so that the amount of oil provided to the cooling region is adjustable, and a controller that receives signals from the one or more sensors and provides control signals to the oil gating system wherein the controller determines the amount of oil to provide to the cooling region based upon the one or more sensors so that the oil provided to the cooling region of the cylinder is reduced to inhibit excess soot production. 
     Another aspect of the invention comprises a system for cooling a piston of an internal combustion engine having at least one cylinder that receives the piston wherein the cylinder defines a combustion region and a cooling region, wherein the internal combustion engine includes an oil supply system that supplies oil to the cooling region of the cylinder, the system comprising one or more sensors that sense performance parameters of the internal combustion engine, an oil gating system that is controllable so that the amount of oil provided to the cooling region is adjustable, and a controller that receives signals from the one or more sensors and provides control signals to the oil gating system wherein the controller determines the amount of oil to provide to the cooling region based upon the one or more sensors so that the oil provided to the cooling region of the cylinder is reduced to improve the efficiency of the motor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of one embodiment of a piston cooling arrangement embodying the invention. 
         FIG. 2  is a schematic view of another embodiment of the invention. 
         FIG. 3  is a block diagram of the closed loop elements comprising the invention. 
         FIG. 4A  is a chart depicting cooling flow vs. (load %), at constant speed in a typical diesel, gasoline, alternative-fuel engine application. 
         FIG. 4B  is a chart depicting piston temperature vs. (load %), at constant speed in a typical diesel, gasoline, alternative-fuel engine application. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to the drawings wherein like numerals refer to like parts throughout.  FIG. 1  illustrates an initial embodiment of a piston cooling lubrication system  100  for a diesel, gasoline, alternative-fuel engine, that comprises an oil lubricating pump  104  which pumps oil from the crankcase  102  through an electronically controlled valve such as a pwm valve  106  through flow passage  112  to a “common rail” oil passage  124  to a plurality of oil spray nozzles  126 ,  130 ,  134 ,  138 . Spray nozzle  126  has a protruding tip  128  which is preferably directed to the bottom side of piston dome  116 , whereas piston  116  moves up and down in engine block  114 . In addition, oil spray tips  132 ,  136  and  140  are pointed to the bottom side of pistons  118 ,  120  and  122  respectively. This embodiment  100  represents a four-cylinder engine configuration as illustrated by pistons  116 ,  118 ,  120  and  122 . 
       FIG. 2  illustrates another embodiment  150  of the present invention and, in particular utilizes the same oil pump  104  to draw lubrication oil from the crankcase  102  to a common rail manifold  152 . The sump oil  102  will flow in a parallel circuit configuration through electronically controlled valves such as pwm valves  154 ,  156 ,  158  and  160 . It will be appreciated that pwm valve  154  flows oil directly through spray nozzle  126  and spray tip  128  where the oil is preferably directed to the underside of piston  116 . This embodiment  150  provides for a pwm valve to manage piston cooling on a per piston basis. In  FIG. 1 , ecm  108  is electronically connected through conductor  110  to pwm valve  106 , hence the ecm controls only one pwm valve  106  for an entire bank of cylinders  116 ,  118 ,  120 ,  122 . Embodiment  150  provides for individual electronic control of each pwm valve  154 ,  156 ,  158 , and  160  by direct connection to ecm  108  output control ports  170 ,  172 ,  174  and  176  respectively. More specifically, the precise oil delivery from pwm valve  154  is fed through oil passage  162  to oil spray nozzle  126  and spray tip  128  to piston underside  116 . Continuing further, pwm valve  156  will deliver oil through oil passage  164  through nozzle  130  and spray tip  132  to piston underside  118 . PWM valve  158  routes oil directly through oil passage  166  through nozzle  134  and spray tip  136  to piston underside  120 . Moreover, pwm valve  160  directly connects oil passage  168  to nozzle  138  and spray tip  140  to cool piston underside  122 . In this fashion, piston cooling management may be accomplished by ecm  108  with the employment of table driven look-up entries on a per piston basis. 
       FIG. 3  represents a block diagram of the closed loop control components of embodiment  100  from  FIG. 1  and embodiment  150  of  FIG. 2 . Closed loop control elements  180  are commonly used in a typical modern day diesel, gasoline, alternative-fuel engine application that incorporates an ecm  108  to perform the task of fuel management/control of fuel injectors (not illustrated). For the purpose of clarifying the explanation of the control methodology, only a single piston  116  of the engine block  114  is illustrated in a cutaway view of embodiment  100  of  FIG. 1  and embodiment  150  of  FIG. 2 . The ecm  108  has a plurality of dedicated hardware input channels  182  for the purpose of reading engine water temperature  194 , oil pump pressure  196 , oil temperature  198  and engine speed  192 , measured by a multi-tooth gear or wheel  188 , spinning past a magnetic pickup  190 . Some diesel engine applications employ a turbo boost sensor  186  input  220 . The present invention capitalizes on the aforementioned sensor feedback to calculate in real time the cooling requirements of piston  116 , based proportionally as a function of the thermal loading imposed on the piston dome of piston  116 . 
     In particular,  FIG. 4A  is an example graph of oil flow  230  in gallons per minute (gpm) versus the Load  234  imposed on the pistons of a typical diesel, gasoline, alternative-fuel engine application. It can be seen that the oil flow  230  is held at a constant level  232  throughout the entire range of Load  234  (0 to 100%) imposed on the engine&#39;s piston domes. The oil flow to the piston underside is held constant to accommodate a worst case load scenario, resulting in an over-cooled piston, producing an excessive amount of soot in the oil and a reduction of engine efficiency. In addition,  FIG. 4B  illustrates that in conventional piston cooling systems, piston temperature  236  increases proportionally  238  based on the imposed Load  234  (at constant engine speed). Referring back to  FIG. 3 , it will be appreciated that the closed loop control methodology  180  enables a precision amount of oil flow be tailored to the piston for cooling at every engine load scenario, and not based strictly on a worst case 100% full load scenario. For example, a light load condition requiring minimal engine fuel consumption may translate the low turbo boost sensor  186  signal  220 , and calculated table look-up 184 values to an output pulse width of 20% to be generated by the ecm  108 . In particular, the pwm output signal  200  is fed to a pwm driver circuit  224 , providing the necessary current and voltage output drive characteristics  202  to modulate the pwm valve  204 . It will be noted that pwm driver circuit  224  is required if the ecm  108  does not have sufficient drive capability to directly interface to pwm valve  226 . The 20% pulse width will provide a signal representing approximately 20% of the maximum oil spray through nozzle  126  and spray tip  128  to the piston underside  116 , representing optimal cooling capability to the piston for a relatively low piston load. In contrast, a much higher load (more fuel used by the engine), may translate to an 85% pulse width, producing a longer duration pulse width signal from ecm output  200 , and driver circuit  224  to pwm valve  226 . This 85% pulse width will provide an oil spray flow rate at the upper end capability of the closed loop cooling system  180  for flowing oil to the output  204  of pwm valve  226  through oil channel  228  to oil nozzle  126  and spray tip  128  to piston underside  116 . The direct current (D.C.) supply voltage connection(s)  208 ,  206  required for powering the pwm valve  226  and for the pwm driver  224  may or may not be the same as the ecm voltage source  210  and is based on the voltage requirement of the pwm valve  226  and pwm driver circuit  224 . In addition, the D.C. voltage source  210 ,  208 ,  206  shall be referenced to circuit ground connections  212 ,  214  and  216 . It will be noted that some vehicle electrical systems, stationary generator sets, and marine applications may not use the customary 12 VDC supply source. 
     Although the foregoing description of the preferred embodiment of the present invention has shown, described and pointed out the fundamental novel features of the invention, it will be understood that various omissions, substitutions and changes on the form of the detail of the apparatus as illustrated as well as the uses thereof, may be made by those skilled in the art without departing from the spirit of the present invention. Consequently, the scope of the present invention should not be limited to the foregoing discussion, but should be defined by the appended claims.

Technology Category: 2