Control system and method to mitigate reverse oil flow to the combustion chamber on deactivated cylinders

Abstract

This disclosure generally relates to an oil mitigation system and method for lubricating the piston(s) for electronic fuel injected internal combustion engines, incorporating cylinder deactivation technology. This concept leverages the engine's base fuel injection pulse width table, determines the fuel injection “shutoff” state and, reduces the oiling to counter the reverse oil flow effect within the cylinder wall, past the ring set to the cylinder combustion chamber. This disclosure further comprises a system and method for mitigating oil consumption to all active cylinders, for accommodating all ranges of engine loading.

Claims

1. A system for mitigating the amount of oil that is consumed by the combustion chamber during cylinder deactivation, cylinder cutout, Jacob-braking, engine-braking functionality of an electronic fuel injected internal combustion engine, including both compression-ignited and spark-ignited, an engine control system that manages fuel injection on an individual cylinder basis and, sensors that measure a plurality of engine control parameters including rpm, vehicle throttle position and, manifold pressure, comprising; at least two cylinders; and an oil sump and oil pump supply system to provide lubrication-cooling oil through a solenoid valve control system in communication to an oil jet nozzle to the piston dome underside and cylinder wall of each individual cylinder; and an oil mitigation control system in communication to the engine control system, wherein the lubricating oil delivered to each cylinder assembly is adjustable; and said oil mitigation control is adapted to sense and receive a continually updated fuel injector pulse width for each fuel injector, including a routine to convert said pulse width to an oil duty cycle Percentage value for each cylinder for controlling a solenoid valve in communication with each individual activated/deactivated cylinder, whereby this oil duty cycle percentage value operates the oil solenoid valve to provide a corresponding let spray to the piston underside; and said oil mitigation system uses said fuel injection pulse width table to create an oil jet duty cycle table, scaled linearly, wherein a zero or substantially low pulse width represents a 0% or substantially low oil jet duty cycle and, a maximum pulse width translates to a 100% oil jet duty cycle, providing full oil flow to the piston underside; and said oil mitigation system further comprising a software evaluation-matching filter, to route said oil jet duty cycle value to each cylinder, to one of a plurality of oil flow ranges to mitigate lubrication over a full spectrum of said cylinder assembly load demands for each activated/deactivated cylinder; and said oil mitigation system further comprising a range configured to provide a deactivated cylinder the minimum quantity of lubrication oil, whereby a cylinder in deactivation, requires the slightest quantity of lubrication to overcome frictional forces.

2. The system of claim 1, wherein said oil mitigation control comprises at least one solenoid valve for each cylinder, preferably configured for armature or plunger position feedback.

3. The system of claim 1, further comprising a plurality of said ranges configured to accommodate lubrication for deactivation and idle, low-load, medium-5 low-load, medium-high-load and, full-high-load.

4. A method of mitigating lubricating oil from entering the combustion chamber, in a fuel-injected, spark-ignited, compression-ignited, internal combustion engine, having at least two cylinders comprising cylinder deactivation, cylinder cutout, Jacob-braking, engine-braking technology, the method comprising the steps of: sensing an operator demand requesting various power levels for lubricating each cylinder assembly; and providing a plurality of power level bands or ranges anticipated in providing lubrication for operating said cylinder assembly; and mitigating lubricating oil to said cylinder assembly in both deactivated and activated states, whereby delivering oil in a closed-loop means to both deactivated and activated cylinders, wherein reading a continually updated value of pulse width from a base fuel infection table for determining said power level exerted on said cylinder assembly, further comprising a means of converting said fuel injection pulse width to a duty cycle value for controlling a pulse-width- modulated solenoid valve, whereby said duty cycle values reflect the lubrication Quantity of oiling to manage the forces exerted on said cylinder assembly, further organizing said duty cycle values generated by said fuel infection system, to a table, preferably comprising five groupings of twenty duty cycle values each, in ascending order, whereby said duty cycle values are ordered from zero to one hundred percent, and wherein mitigating lubrication to said cylinder assembly, comprises controlling lubricating oil through said solenoid valve, through a flow nozzle pointing toward the piston dome underside and cylinder wall assembly.

5. The method of claim 4, wherein each said grouping is comprised of a 30 dominant lubricating duty cycle template value predetermined in a non-volatile table, wherein lubrication is delivered preferably by five distinct duty cycle values, 20%, 40%, 60%, 80% and 100%, respectively placed in said groupings called deactivation-idle, low-load, medium-low-load, medium-high-load, full-high-load.

6. The method of claim 5, further comparing each incoming duty cycle value through a software evaluation mechanism such that said incoming duty cycle value is assigned to the closest of said five dominate lubrication duty cycle values, whereby the lubrication quantity will closely align with said cylinder assembly's exerted load.

7. The method of claim 6, wherein said incoming duty cycle of 0% indicates a cylinder undergoing a state of deactivation or inactivity, whereby lubricating said cylinder assembly is substantially reduced.

8. The method of claim 4, wherein closing the loop around one of said five dominant desired oiling duty cycles, using a proportional-integral control, whereby allowing for ample range overlap for the entire imposed load spectrum.

9. The method of claim 8, wherein position feedback for said solenoid valve's plunger is managed by measuring the shunt current draw comprising a position loop gain term, a position proportional gain term and, a position integral gain term.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a more complete understanding of this disclosure, reference is made to the following description, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 depicts a schematic illustration embodying the present invention.

(3) FIG. 2 depicts a block diagram of the oil mitigation control strategy for use with the present invention.

(4) FIG. 3 is a flowchart illustrating the software lubrication/oiling rules controlling the oil jet solenoids of the present invention.

DETAILED DESCRIPTION

(5) The embodiment described in the present invention is by way of illustration only and should not be construed in any way, to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any type of suitably arranged device or system. The drawings may not necessarily be to scale and certain features illustrated in a schematic form. As used in the specification and claims, for the purpose of describing and defining the disclosure, the term “substantially” is used herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. “Comprise”, “include”, and/or plural forms of each are open-ended, include the listed parts, and can include additional parts that are not listed. For purposes of clarity, the same reference numbers apply to FIGS. 1 and 2, wherein, FIG. 3 is a software flowchart, further defining module 68 of FIG. 2. As used herein, the term module refers to an application specific integrated circuit (ASIC), a processor that is shared, dedicated, or part of a group and memory that executes firmware, software, combinational logic circuits that perform the functionality of this invention. In addition, the processes of lubricating and oiling may be used interchangeably, wherein both processes function to lubricate and cool the piston(s) and cylinder wall(s).

(6) FIG. 1 includes a compression-ignition and/or a spark-ignition, 2-cylinder configuration engine 10, that comprises an oil lubricating, fixed or variable displacement pump 12, that pumps oil from the sump 14 through a flow passage 16 to a “common-rail oil manifold” 18, to oil jet solenoid(s) 20, 22. Common-rail 18 is in communication to inlet oil port(s) 24, 26 of oil jet solenoid(s) 20, 22 respectively. Oil jet nozzle(s) 28, 30 are in communication with each outlet oil port of each solenoid valve 20, 22 respectively and, illustrates delivery of oil to “additional valves” as necessary. Oil jet nozzle(s) 28, 30 are preferably directed upward to piston dome underside(s) 32, 34 of cylinder(s) 36, 38. Piston dome(s) 32, 34 move up and down within piston cylinder(s) 36, 38 and, fuel is injected through electronic fuel injector(s) 40, 42 into combustion chamber(s) 44, 46, wherein combustion chamber (firedome) 44 illustrates substantial combustion activity.

(7) ECM 50 comprises a CPU 52, System Clock 54, Memory 56 (includes RAM, EEPROM, FLASH), memory look-up tables, including BOI 58, DEMAND TORQUE 60, TORQUE/RPM/BOI 62, FUEL INJECTION MODULE 64, Fuel Injector Driver 66 and the fuel injector(s) 40, 42. The Oil Jet Lubrication Control 68, is in communication with both the ENGINE CONTROL ROUTINES 70 and the Oil Jet Solenoid Valve Driver 72. A programmable timer module (PTM) 74 is also in communication with the Oil Jet Solenoid Valve Driver 72 and, specifically, is responsible for creating the base frequency and duty cycle modulation for driving the solenoid valve(s) 20, 22. Electronic control signal lines 76, 78 interface the oil jet module 72 to solenoid valve(s) 20, 22. It will be appreciated that a “shunt current”circuit exists in Block 72 (not illustrated) for each oil jet solenoid 20, 22 as a method to sense feedback current. Each oil jet solenoid is controlled independently to maintain the “desired” oil jet duty cycle in a Proportional/Integral (PI) control-loop (not illustrated in FIG. 1). In addition, Block 72 includes a logic output solenoid valve drive circuit that can sense a “stuck high” or “stuck low” voltage level condition, wherein ECM 50 is placed in a “limp-home-mode” (not illustrated). An oil spray pattern 80, 82 is illustrated flowing different quantities of oil to piston dome underside(s) 32, 34, and in particular, is based on the commanded duty cycle of the respective oil jet solenoid valve(s) 20, 22.

(8) The SENSORS 84 block represents sensors commonly used on spark-ignition and compression-ignition engines 10 and may include but not limited to manifold absolute pressure (MAP), engine speed (RPM), vehicle throttle position, engine oil temperature, oil pressure, coolant temperature (individual sensors not illustrated). Note, the dashed boundary line (86) within ECM 50 and Engine 10, indicates the “smart firedome” system.

(9) Turning to FIG. 2, the electronic control module controls the fuel to the engine, based on reading ECM Inputs of vehicle throttle position (TPS) and engine speed (RPM) and then locates and retrieves corresponding EEPROM table values of both DEMAND TORQUE 60 and BOI 58. GOVERNOR CONTROL 90 makes a determination if adjustments are required to the demand torque value, i.e., smoke limiting, over temperature conditions, over-load torque limiting, and other engine conditions. From here, the non-volatile TORQUE/RPM/BOI 62 module calculates a final pulse width and converts the value to a percentage duty cycle for the FUEL INJECTION MODULE 64. The Fuel Injector Driver 66 receives a duty cycle modulated signal from the FUEL INJECTION MODULE 64 and provides the fuel injector(s) 40, 42 the proper fuel to supply the ENGINE 10. The fuel injector(s) 40, 42 provides a “plunger position feedback” signal to the Fuel Injector Driver 66, wherein plunger position sensing is managed through a shunt current feedback circuit (not illustrated).

(10) The OIL JET Lubrication Control 68 receives a continuous updated “oil jet % duty cycle value” representing fuel injection (not illustrated). This value is evaluated through a set of software “lubricating/oiling rules” and, specifically, evaluated for equivalence by a set of five specific “Case” scenarios (discussed in FIG. 3). Each Case statement “evaluates” for a match and then sets the updated value of the duty cycle to one of five specific discrete duty cycles (see FIG. 3), referenced in FIG. 2 as “desired oil”. Summing junction 92 receives the “desired oil” duty cycle at the “positive” input, wherein the output of Summing junction 92 becomes the “position error” signal driving the input of the PI Control 94. The output of PI Control 94 becomes the “finalized oil” signal to duty cycle modulate solenoid valve(s) 20, 22, wherein, “valve position feedback” completes the closed-loop through the “negative” input of Summing junction 92. Valve position feedback is sensed by a shunt circuit within the Oil Jet Solenoid Valve Driver 72, through interface signal connections 76, 78 (see FIG. 1) of solenoid valve(s) 20, 22. As an example, Texas Instrument manufactures an ASIC that has a “Back-EMF” sensing circuit to measure the average current draw of a solenoid's plunger (armature) for modulating an electro-mechanical solenoid. The OIL JET Lubrication Control 68 includes a plunger-position-loop-gain term, position-proportional-gain term, position-integral-gain term (not illustrated) and, specifically, located in a non-volatile memory table 56 (FIG. 1).

(11) Turning now to FIG. 3, block 100 defines a software entry point for evaluating the fuel injection duty cycle (same as oil jet % duty cycle) that becomes filtered by dropping through “Case” statements (1 through 5) and evaluated for a match within the duty cycle range, defined in each Case statement. As an example, if the fuel injection duty cycle is 82% at the input of Case 1: (102), then 82% falls between the defined values of (81-100%) and will take the “Yes” path to block 112. Block 112 is responsible for setting the “finalized oil” duty cycle to a value of 100% and, in particular, shall flow an oil pattern 80 (FIG. 1) representative of a “full-high-load”point. Looking at another example, if a commanded fuel injection duty cycle of 18% is retrieved at software block 100, then Case 1: (102), Case 2: (104), Case 3: (106), and Case 4: (108) are evaluated to take the “No” branch. Case 5: (110) decision branch, evaluates 18% to be between the values of (0-20%) and takes the “Yes”branch to block 120, wherein, the “finalized oil” duty cycle is set to 20%. It will be appreciated that the present invention has the ability to automatically sense (detect) a cylinder-cutout and/or a cylinder-deactivation state of the engine (0% fuel injection duty cycle) and, specifically adjusts the “finalized oil” duty cycle to be 20%. Turning again back to FIG. 1, oil pattern 82 illustrates an engine in a deactivated state (note: the absence of combustion chamber 46 activity). A duty cycle of 20% provides a substantially reduced level of lubrication for deactivation, cutout, and idle, compared against present oil mitigation strategies on the market, however; shall provide a safety margin to overcome the frictional forces generated by the reciprocating piston with fuel injection shut-off. The present invention provides for generating a total of five discrete oiling flow quantities, i.e., 100% at block 112, 80% at block 114, 60% at block 116, 40% at block 118, and 20% at block 120. Discrete oiling ranges provide for overlap with many different engine types, horsepower ranges, and variations in engine ECM calibrations and, in particular, designed to provide a “lead” control factor to provide a level of safety margin to prevent under-oiling for all load ranges. The present invention provides for intermediate levels of mitigated oiling and, specifically, Case 2 (114) provides for oiling at loads less than or equal to “medium-high-load”, wherein Case 3 (116) for loads less than or equal to “medium-low-load” and, Case 4 (118) for oiling less than or equal to “low-load” loads. The present disclosure mitigates oil usage to cover all ranges of engine loading and rpm and, in particular, substantially reduces oil lubrication needs for cylinder cutout, cylinder deactivation, Jacob-brake, engine-brake applications, wherein, fuel injection is shutoff

(12) While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the scope of this disclosure, as defined by the following claims.